JPH03212154A - Power supply - Google Patents

Abstract

PURPOSE:To interrupt all power supplies in a device, upon occurrence of abnormality in a switching power supply, by inserting a temperature detecting element to a power supply path to be thermally coupled with a surge current suppressing resistor, such that it is opened upon temperature rise over a predetermined level. CONSTITUTION:A surge current suppressing resistor R1 is connected in parallel with a triac T1 and a temperature detecting element, i.e. a temperature fuse TF thermally coupled with the surge current suppressing resistor R1, is connected in series with a current fuse F. When a transistor Q1 is short-circuited due to fault, the triac T1 is brought into nonconducting state and a high current flows through the surge current limiting resistor R1. Consequently, loss of the surge current suppressing resistor R1 increases to cause temperature rise. When the temperature exceeds a predetermined level, the temperature fuse TF is blown off to interrupt power supply to all circuits. By such arrangement, power supply to all circuits in a device can be interrupted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a power supply device that drives a plurality of circuit blocks using one power supply path.

[Prior Art] As shown in FIG. 2, there has been a power supply section W incorporating a general switching power supply section.

The switching power supply section converts the input DC voltage rectified and smoothed by the rectifier D1 and the capacitor C2 into a high frequency voltage by an inverter composed of a high frequency transformer T r , a transistor Q, and a control circuit (not shown) that switches and drives the transistor Q. Convert, high frequency transformer T r
The DC voltage is returned to DC voltage again by a DC smoothing circuit composed of a rectifier D2, a choke coil L1, and a capacitor C3 connected to the output winding N2 of .

The above rectifier receives power from a commercial power supply through a series circuit of a current fuse F and a resistor R1 with a built-in temperature fuse TF, which constitutes an inrush current suppression circuit. The voltage of the feedback winding N of the high frequency transformer Tr is used as the gate signal of the triac T1. A resistor R2 and a capacitor CI connected in parallel to the feedback winding N constitute a filter for stabilizing the gate signal.

Here, when it is in the Spirit M frame, the input current to the Sui Sosengu Spirit M section passes through path 2, and the inrush current to the capacitor C2 is suppressed by the resistor R1. and capacitor C2
When the potential across the terminals rises, the switching power supply section starts operating, current flows through the primary winding N1 in accordance with the switching of the transistor Q1, and a voltage is also generated in the output winding N1. This voltage makes the triac T conductive, and the input current path of the switching power supply section shifts to I2. As a result, the resistor R1 has a loss only during startup, and has no loss during normal operation.

Another branched circuit S1 has a current fuse F and a resistor R4.
Power is supplied from the connection point.

[Problem M to be solved by the invention] By the way, in this conventional power supply device, if a short circuit occurs between D and 3 due to a failure of transistor Q1, the high frequency transformer Tr
1 stops oscillation and no voltage is generated in the feedback winding N. Therefore, the triac T1 becomes non-conductive, and a large current flows through the resistor R1. Therefore, the loss of resistor R0 increases and the temperature rises. When this temperature exceeds a certain value, the temperature fuse TF built in resistor R1
fuses, cutting off the power supply to the switching power supply section. The blowing current IF of the current fuse F is IF
> (V AC, /R1), so it will not blow out in the above failure mode. Note that VA (is the commercial power supply voltage).

In this case, the function of the switching power supply section stops, but the branched separate circuit S1 maintains its normal state, so it may be difficult to recognize the failure from the perspective of the entire device, or there is a risk of a subsequent failure.

The present invention has been made in view of the above-mentioned points, and its object is to provide a power supply device that shuts off all power supplies in the device when an abnormality occurs in the switching power supply section.

[Means for Solving the Problems] In order to achieve the above object, the present invention has an input power supply path branched into a plurality of systems, and one of the branch paths is equipped with a triac and an inrush current suppressing resistor. In a power supply device having a switching power supply unit that receives power supply through a parallel circuit with an inrush current suppression circuit, the temperature detection element is thermally coupled to the inrush current suppression resistor and becomes open when the temperature exceeds a certain temperature. is inserted into the input power supply path before the first branch point.

[Function] According to the present invention, when the inrush current suppressing resistor overheats during an abnormality in the Swiss/Sochi power supply section, the temperature detection element thermally coupled to the inrush current suppressing resistor opens and stops all power supply. can be stopped.

[Example] The present invention will be explained below with reference to Examples.

FIG. 1 shows an embodiment circuit of the present invention. In this embodiment, an inrush current suppressing resistor R is connected in parallel to the triac T1.
5 is connected, and a temperature fuse TF, which is a temperature detection element thermally coupled to this inrush current suppressing resistor R1, is inserted and connected between the current fuse F and the branch point. The other configurations are the conventional example and the collapse fP km.
, becomes a failure and a short circuit occurs between D and 3.

If a short circuit occurs as described above, the high frequency transformer T
r, oscillation stops and no voltage is generated in the feedback winding N3. Therefore, the triac T becomes non-conductive, and a large current flows through the inrush current suppressing resistor R1. For this reason, the loss of the inrush current suppressing resistor R increases and the temperature rises. When this temperature exceeds a certain level, the temperature fuse TF blows, stopping the power supply to all circuits.

[Effects of the Invention] As described above, the present invention has an input power supply path that branches into a plurality of systems, and one of the branch paths has a triac connected in parallel with an inrush current suppression circuit using an inrush current suppression resistor. In a power supply device having a switching power supply section that receives power supply through a circuit, a temperature detection element that is thermally coupled to the inrush current suppressing resistor and becomes open when the temperature exceeds a certain temperature is inputted before the branch point. Since it is inserted into the power supply path, if an abnormality occurs in the switching power supply, the power supply to all circuits in the same device can be cut off, reducing the possibility of secondary failure even before the failure is recognized. It has the effect of cutting off the

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention, and FIG. 2 is a circuit diagram of a conventional example. VAe is a commercial power supply voltage, T1 is a triac, R is a resistor for suppressing rush current, Q is a transistor, T r is a high frequency transformer, Sl is a separate circuit, and TF is a temperature fuse.

Claims (1)

[Claims] (1) Switching where the input power supply path branches into multiple systems, and one of the branch paths receives power through a parallel circuit of a triac and an inrush current suppression circuit using an inrush current suppression resistor. A power supply device having a power supply section, characterized in that a temperature detection element that is thermally coupled to the inrush current suppression resistor and becomes open when the temperature exceeds a certain temperature is inserted in the input power supply path before the branch point. and power supply equipment.