JPS63262058A - Power source - Google Patents

Abstract

PURPOSE:To enhance the safety and the reliability of a power source by regulating voltage and current limiting means of the main bodies of a protection section, and then constructing so that predetermined output characteristic is obtained by the limiting means. CONSTITUTION:A power source converts the power of a commercial power source 1 by a rectifying and smoothing unit 2 to DC, and applies it to a switching element 3. The element 3 is connected in series with a current detector 4 and an inductance 5, and turned ON, OFF by a controller 9. A current I thus intermittently fed is so converted by the inductance 5 and a rectifying and smoothing unit 6 as to apply a predetermined DC voltage E to a load 8 through the series circuit. The voltage E is monitored by a voltage detector 7, and output to the controller 9. The controller 9 has a logic unit 93, a time limiter 92 and an output unit 91, and turns OFF the element 3 when a logic output D is '0'. Thus, the safety and the reliability of the power source are enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power supply device that obtains a stable DC voltage by intermittent current flow, a so-called switching regulator.

There are many types of power supply devices using this method, but all of them generate a stable DC voltage by passing current intermittently through an inductance such as a chiroku or tofunsu inductance, and controlling the cycle and intermittent ratio. Due to the need to interrupt current at high speed, various semiconductor devices such as thyristors,
Transistors, F'ETs, etc. are used, but these switching elements are used under operating conditions that take either a completely on state or a completely off state, i.e., under switching operating conditions, and therefore, transient The power consumed by the switching element is very small, except under normal conditions. Combined with the shortening of the intermittent cycle, it is possible to use a small capacity switching element to create a highly efficient, compact and lightweight power supply device. .

However, semiconductor switching elements have a lower overcurrent capability than mechanical switching elements such as relays, so when the power is turned on when the rectifier and smoothing section on the output side or the load is uncharged, or when an abnormality occurs on the input or output side. It is necessary to protect against overcurrent from flowing in the event of an overcurrent, and since many of the devices connected as loads for this type of power supply have semiconductor-based components, the output voltage of the power supply If it is too high for some reason, there is a high possibility that an abnormality will occur in the load, and some kind of protection is required.

As described above, various protection parts are essential for this type of power supply device, but the conventional design concept focuses on obtaining the required input/output characteristics, and after that is achieved, various protection parts are added incidentally. was added. Therefore, the circuit configuration tends to become redundant and complicated, and the number of parts tends to increase.

The present invention has been developed based on a design concept that is contrary to the conventional design concept in order to overcome the current situation.Firstly, the voltage and current limiting means, which are the main components of the protection section, are investigated, and then the limiting means is The aim is to obtain the required output characteristics. Therefore, the various protection parts that were conventionally considered accessories become the main components of the device, which has the advantage of increasing the safety and reliability of the device and making the overall structure extremely simple.

Hereinafter, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of the main parts of the power supply device according to the present invention, in which power supplied from a commercial power source 1 is converted into direct current by a rectifying and smoothing section 2.

applied to the switching element 3. The switching element 3 is connected in series with the current detection section 4 and the inductance 5,
The control is performed on and off by the control section 9. The current cut off and on by the switching element 3 flows through the series circuit and is converted by the inductance 5 and the rectifying and smoothing part so that the required DC voltage E is applied to the load 8. The DC output voltage E is monitored by the voltage detection section 7. For convenience, the commercial power supply 1 side from inductance 5 is the input side,
The side from the inductance 5 to the load 8 will be called the output side. The current detection unit 4 constantly monitors the instantaneous value of the current flowing through it, and outputs a logical output A of 1 or 0 depending on whether the current value is larger or smaller than a predetermined current value. The voltage detection unit 7 constantly monitors the output voltage E, and its value is a predetermined voltage 1i1! Is it bigger or smaller than υ?
Outputs logic output B of 1 or O. The control section 9 includes a logic section 93, a time limit section 92, and an output section 9], and the logic section 93 receives the logic output A from the current detection section 4 and the logic output B from the voltage detection section 7. As logical sum C=A+B
It performs a logical operation and outputs a logical output C. The time limit section 92 is a negative type time limit element that receives the logic output C and outputs the logic output R, and the logic output R is 1 when the logic output C is 0, and is constant from the time the logic output C becomes 1. O is shown only during the time limit T of . The output section 91 receives a logic output and converts it into an output that can control the switching element 3. When the logic output is 1, the switching element 3 is turned on, and when the logic output is O, the switching element 3 is turned on. Turn off.

Needless to say, in the actual configuration, hysteresis characteristics are provided in various parts mainly for stabilizing the operation of the detection circuit, but the explanation will be omitted since it will complicate the explanation. Also, most of the operating elements of each part are concretely realized by integrated circuits, so it seems meaningless to represent them as individual parts that perform a single operation, but some of them are forced to be expressed as individual parts. For example, the current detection unit 4 is a resistor through which a current flows, and a transistor circuit that amplifies the voltage across the resistor to form a logical output, or a current flow through a current transformer and its secondary side. This can be implemented by converting the output into a logical output form using a transistor circuit.

With the above configuration, when the commercial power supply 1 is applied, a required output voltage is applied to the load 8. This will be explained with reference to FIG. 2.

FIG. 2 schematically shows the operating waveforms of each part corresponding to time t. When the commercial power supply 1 is applied at time to, the rectifying and smoothing part 2 converts this into direct current, and the switching element However, since the rectifying and smoothing section 6 and the load 8 are uncharged at that point, the output voltage E is low.

Furthermore, even if current begins to flow, its value is small because of the inductance 5. Therefore, both logical outputs A and B are O, and naturally the logical output C, which is A+B, is also zero.

Therefore, the logic output is 1, and the output section 91 controls the switching element 3 to be on. As a result, the electric current begins to increase, but because of the inductance 5, it does not rise suddenly.
In the range where the inductance 5 is linear, it increases linearly. When the current decrease reaches the set value k at time t1, the logic output A becomes 1, and naturally the logic output C also becomes 1, and the logic output becomes 0. Therefore, the switching element 3 is turned off and the logic outputs A and C both become 0, but the time limit section 9
The logic output of No. 2 holds O for the time limit T. During this period, the output voltage E increases to a certain value at time t, but it is consumed by charging the rectifying and smoothing section 6 and by the load 8, so the time limit T
At later times, it will drop to some extent. When it becomes a time object, the logic output becomes 1 and the current begins to flow again. Thereafter, this operation is repeated and the output voltage E gradually increases.

When the output voltage E reaches the set value Ec at time tn,
Even if the current drop does not reach the set value IC, the logic output B of the voltage detection section 7 becomes 1, so the logic output C becomes 1, and the logic output becomes 0, and the switching element 3 becomes OFF, and the current drop becomes 0. Cut off. As a result, when the output voltage E decreases by more than the set value Ec, the switching element 3 is turned on and a current flows by an amount that compensates for the decrease. Thereafter, this operation is repeated so that the output voltage E is kept at a more or less constant voltage &.

As shown between time tyu4 and time tnr3, if the output voltage E falls below the set value Ee during the time limit T due to a sudden change in load, etc., the switching element 3 does not turn on immediately; The switching element 3 is turned on only after the time limit T has elapsed from the time two←. At this time, the output voltage E decreases a little more than the value in the steady case, but this amount is compensated for when the switching element 3 is next turned on, and the output voltage E is almost maintained at the set value k.

As mentioned above, each part has hysteresis, so
The output voltage E slightly fluctuates around the set value Ec and a ripple portion occurs, but this is an unavoidable phenomenon in this type of power supply device, a so-called switching regulator, which obtains a constant voltage through on/off control.

As can be seen from the above explanation, in the power supply device according to the present invention, even if any factor such as an increase in input voltage or a short circuit in the load is added, the switching element 3 and the inductance 5 connected in series with it will have a value higher than the set value IC. current does not flow. Furthermore, when the output voltage exceeds the set value &, the switching element 3, which is the basis of power conversion, is turned off, so that there is no possibility that the output voltage E will rise excessively. Furthermore, the maximum current flowing through the inductance 5 is below the set value C,
The time during which the current is cut off is the time limit time T of the time limit section 92.
Each can be set arbitrarily, and since these are the basis of operation, it is possible to completely prevent inductance oversaturation and insufficient reset phenomena, which often occur in switching regulators. It is well known that the value of the C1 time limit T below the set value of these currents is determined in consideration of the output capacity of the power supply, the rating of the switching element, the required reset time of the inductance, etc. Also, the fact that the maximum current flowing through the inductance 5 and the time during which the current is cut off is determined means that the maximum power supplied to the load 8 is determined, and the output current is lower than a certain value. This means that as the voltage increases, the output voltage E decreases, which is a so-called drooping characteristic. Therefore, safety in the event of an accident on the load side is improved, and parallel operation of the power supply devices becomes extremely easy. On the other hand, if the droop characteristic is actively utilized, new applications can be developed, such as a power source for a load with a negative characteristic, such as a discharge lamp, where a ballast can be omitted.

As explained above, according to the present invention, on the input side, the switching element 3 and the inductance 5 are connected in series with the current detecting section 4 which outputs the logic output 1 or O according to the setting value of the current flowing therein. , and has a voltage detecting section 7 on the output side that outputs a logic output of 1 or 0 according to whether the output voltage E is larger or smaller than the set value Ec, and has a logic section 93 inside which performs an OR operation and receives the logic output. A control section 9 is provided, which includes a time limit section that performs a time limit operation and outputs a negative logic output in response to an input, and an output section 91 that receives the logic output, and outputs the logic outputs of the current detection section 4 and voltage detection section 7. is connected to the logic section 93 as an input, and connected so that the logic output of the output section 91 controls the switching element 3 to be on or off according to 1 or 0, and has a high level of safety and reliability. You can get a high power supply.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the main parts of the power supply device according to the present invention,
FIG. 2 schematically shows operating waveforms of each part of the power supply device shown in FIG. 1. 1-1 Commercial power supply. 2.6 - Rectifying smooth section. 3--Switching element. 4--Current detection section. 5--Inductance. 7- Voltage detection section. 8-One load. 9-1 control unit. 91-1 output section. 92-One-time period. 93
-Ichirin Ribu.

Claims (1)

[Claims] The switching element 3, the current detection section 4, and the inductance 5 are connected in series on the input side, and the voltage detection section 7 is arranged on the output side. A control section 9 is provided, which includes a time limit section 92 that operates and an output section 91 that controls the switching element 3 in response to the logic output thereof, and controls the respective logic outputs of the current detection section 4 and the voltage detection section 7. A power supply device configured to supply power to the logic section 93 inside the section 9.