JPH03107326A - Power supply - Google Patents

Abstract

PURPOSE:To protect a load by measuring with a timer the time when the load current detected by a current detector has a specified value larger than the normal value but yet smaller than the abnormal value to be cut off, and interrupting the power supply if the condition has continued for a specified time. CONSTITUTION:An AC power source is connected to a load 1 through a power supply stabilizing circuit 2, a current detecting resistor 3, and an interrupting circuit 4. The voltage drop across the current detecting resistor 3 is amplified with an amplifier 5, and it is inputted to the A/D conversion port 7 of a microcomputer 6. And, if the load current has an abnormal level requiring interruption of the power supply, the interrupting circuit 4 is operated immediately. When the load current has a specified value higher than the normal value but lower than the abnormal value, the value is inputted to a memory 9 and a timer 8 starts. If the current of the specified value continues until the timer 8 reaches a specified value, an output of the microcomputer 6 lets the interrupting circuit 4 to operate. And, this prevents the heat generation from a load such as solenoids, transistors, capacitors, etc., and consequently prevents smoking and firing.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a power supply circuit used in electronic equipment, etc., and more specifically, when supplying current to a load of electronic equipment, etc., it responds to an abnormal state of the load. This invention relates to a power supply circuit that controls the interruption of supply current.

[Conventional example] Conventionally, this type of power supply circuit has a circuit configuration that stabilizes the output current against load fluctuations, etc., and this power supply circuit also has a circuit configuration that prevents abnormal current from flowing to the load. Therefore, an abnormal current detection circuit, an output limiting circuit, or a cutoff circuit is provided.

In other words, when the load current reaches an abnormal value, the current supplied to the load is limited or the current is shut down.
FF L, protecting the load.

[Problem to be solved by the invention] By the way, if there is an abnormality in the above power supply circuit, for example.

Since the current setting value was determined in accordance with the maximum value of load fluctuation, there was a problem with responsiveness to load fluctuation. In other words, even if the energization time of the solenoid, transistor, etc. as the load mentioned above exceeds the specified time range, the detected current may not reach the abnormal value, and extra current may flow due to reverse connection of the capacitor. . In such a case, more current than necessary flows through the solenoids, transistors, capacitors, etc., causing smoke and ignition due to the heat generated by them, and damage to these parts.

This invention was made in view of the above problems.

The purpose is to provide a power supply circuit that protects each electronic component of a load and that can determine whether to turn off the power depending on an abnormal state of the load.

[Means for Solving the Problems] In order to achieve the above object, the present invention supplies a current to a load, detects this current, and when the detected current reaches an abnormal value, the supplied current is In a power supply circuit that limits the output of current or cuts off the supply current, a timer means for measuring the time during which the detected current reaches a predetermined value lower than the abnormal value; and a control means for comparing the measured time and a predetermined time and controlling cutoff of the current according to the comparison result, and a storage means for storing the predetermined value and the predetermined time. The main point is that

In addition, in the present invention, instead of the predetermined value and predetermined time, the storage means stores various patterns of the predetermined value and predetermined time corresponding to the state of the load, and The pattern is compared with the pattern in the storage means, and the abnormal state of the load is determined based on the comparison result.

The cutoff of the above-mentioned supply current is controlled.

[Function] With the above configuration, if the load is not in a normal state, for example, if the energization time of Lee μ exceeds the specified time, if the capacitor is reversely connected, or if the load current has not reached an abnormal value. There is. At this time, when the detected current reaches a predetermined value (a value lower than the abnormal value), the timer means measures the time during which the detected current reaches this predetermined value. Further, the detected current value and the measured time are compared with the values stored in the storage means, and it is determined whether or not the load is abnormal based on the comparison result. If the load is abnormal, the current supplied to the load is cut off.

Therefore, if the current value corresponding to the abnormal state of the load and the time data for which the current is flowing are stored in the storage means in advance, the load current does not reach the abnormal value, but the load is abnormal as described above. If this occurs, the power can be turned off to protect the load.

[Example] Embodiments of the present invention will be described below based on the drawings.

In the figure, the power supply circuit includes a power supply stabilization circuit 2 that applies voltage to a load 1 and supplies current to the load, a resistor 3 for detecting the current, and a resistor 3 that cuts off the current supplied to the load 1. With the cutoff circuit 4.

An amplifier 5 that amplifies the voltage drop across the resistor 3, converts this amplified voltage into digital data to use as detected current data, compares this detected current with a predetermined value a, and calculates the time during which the current is flowing. A control circuit 6 is provided which compares the load current with a predetermined value t, determines an abnormal state of the load 1 based on the comparison result, and controls the cutoff circuit 4 to cut off the load current. Therefore, the control circuit 6 is, for example, a microcomputer having a timer 8 for measuring the time during which the detected current flowing through the A/D conversion port and the A/D conversion port reaches a predetermined value or more.

Further, this microcomputer includes a memory 9 for storing the predetermined value a and the predetermined time t, and a memory 9 for storing the predetermined value a and the predetermined time t.
and the detected current, and also compare the above predetermined value t and the timer 8.
Comparison means are provided for comparing the time.

Here, when AC power is supplied to the power supply circuit and a voltage is applied to the load 1 in this power supply circuit.

Assume that for some reason the energization time of the solenoid, etc. of load 1 is longer than the specified time, or that the capacitor is reversely connected. At this time, the current of load 1 is
This detected current is digitally converted by the control circuit 6, and the data of this detected current is compared with a predetermined value a in the memory 9. Note that the predetermined value a is set to a value when the load is in an abnormal state.

Subsequently, when the detected BJl current reaches a predetermined value Ma.

The timer 8 is activated, and the time of this timer 8 and the predetermined time t
A comparison is performed. Furthermore, the comparison between the detected current and the predetermined value a is performed until the predetermined time t has elapsed. Even after the predetermined time t has elapsed, for example, if the detected current continues to reach the predetermined value a, it is determined that the load is in an abnormal state, and the current supplied to the load 1 is cut off. A control signal for this is output to the cutoff circuit 4.

Then, the supply current to the load 1 is cut off by the cutoff circuit 4,
Since the energization of the solenoid, capacitor, etc. is stopped, heat generation in the solenoid, capacitor, etc. is prevented, and smoke and ignition do not occur.

Note that the above embodiment may be used in combination with the operation based on abnormal current detection in the conventional example. In other words, when extremely abnormal current flows to the load 1 due to a short circuit in the load 1, the supplied current is controlled by the conventional circuit. This is because it can be blocked.

Further, various patterns of current values and time values corresponding to the current fluctuations of the load 1 may be stored in the memory (storage means) 9 of the control circuit 6.
It may be determined whether the pattern of the data obtained via the /D conversion port 7 and the time data from the timer 8 matches any pattern stored in the memory 9. In this case, if one of the various patterns to be stored in the memory 9 is, for example, a value when the load 1 is in a normal state, a control signal that triggers the cutoff circuit 4 is output when the above judgments do not match. . Thereby, when the load 1 becomes abnormal, the supply current to the load 1 is cut off, so that heat generation, smoke generation, and ignition of the load 1 can be prevented in advance.

In this way, the abnormal state of load 1 is determined based on the current being supplied to load 1 and the time during which this "heavy membrane" is flowing, so that, for example, the energization time of a solenoid transistor, etc. If the voltage is exceeded, or if the capacitor is connected in reverse, conventionally it would be determined that there is no abnormality in load 1, even though there would be an abnormal situation in the solenoid, transistor, capacitor, etc. In the invention, an abnormality can be detected by the above judgment, and the supply current can be cut off.

[Effects of the Invention] As explained above, according to the power supply circuit of the present invention, the current of the load is detected, the abnormal state of the load is determined based on the load current and the time during which this current is flowing, and the Since the supplied current is cut off, even if an abnormal value of current is not flowing through the load, if the energization time of the load is longer than the specified time width, or if the capacitor is reversely connected, the supply will be interrupted. Since the current is cut off, for example, it is possible to prevent the loads such as solenoids, transistors, capacitors, etc. from generating heat, thereby preventing them from emitting smoke or catching fire, thereby protecting the loads.

[Brief explanation of drawings]

The figure is a schematic circuit diagram of a power supply circuit showing an embodiment of the present invention. In the figure, 1 is a load, 2 is a power supply stabilization circuit, 3 is a resistor (for current detection), 4 is a cutoff circuit (for supply current cutoff), 5 is an amplifier (for current detection), and 6 is a control circuit (microcomputer) , 7 is an A/D conversion board 58 is a timer, and 9 is a memory.

Claims (2)

[Claims] (1) In a power supply circuit that supplies current to a load, detects the current, and limits the output of the supply current or cuts off the supply current when the detected current reaches an abnormal value, a timer means for measuring the time during which the detected current reaches a predetermined value lower than the abnormal value; and a timer means for comparing the detected current and the predetermined value, and comparing the measured time and the predetermined time, and calculating the comparison result. 1. A power supply circuit comprising: a control means for controlling interruption of the current according to the current flow; and a storage means for storing the predetermined value and the predetermined time. (2) Instead of the predetermined value and predetermined time, the storage means stores various patterns of the predetermined value and predetermined time corresponding to the state of the load, and the pattern based on the detected current and the measurement time and the A pattern stored in a storage means is compared with a pattern stored in the storage means, an abnormal state of the load is determined based on the comparison result, and cutting-off of the supply current is controlled.
1) Power supply circuit described.