JPH11329760A - Power supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain a rush current generated in driving a load of which impedance is changed depending on temperature. SOLUTION: This power supply device senses the temperature of an incandescent lamp 10 by a temperature sensor 6 when a switch S1 is turned on and controls the pulse width of a control pulse P output from a control circuit 7 based on the temperature sensed by the temperature sensor 6. Thereby, the device controls a time until a lamp terminal voltage applied to the incandescent lamp 10 reaches a predetermined voltage depending on the impedance of the incandescent lamp 10.

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 supplying a drive voltage to a load whose impedance changes depending on the temperature of, for example, an incandescent lamp or a heater.

[0002]

2. Description of the Related Art It is known that a load such as an incandescent lamp or a heater changes its impedance depending on the temperature. For example, impedance characteristics of an incandescent lamp, a heater, and the like with respect to the temperature are such that when the temperature is low, the impedance is low, and as the temperature increases, the impedance increases.

For this reason, when a rated voltage is applied from a power supply device when the impedance of the incandescent lamp or the heater is low, the incandescent lamp or the heater reaches a predetermined temperature until the impedance reaches a predetermined impedance. A large inrush current (hereinafter, referred to as a “rush current”) flows through each circuit unit constituting the power supply device in comparison with the normal operation. Therefore, in a conventional power supply device for driving an incandescent lamp, a heater, or the like, each circuit component constituting the power supply device, such as a fuse, a bridge diode, a filter circuit, or the like, is made to withstand even when a rush current flows. Larger rated ones were used.

[0004]

However, when a rush current flows in the power supply as described above, excessive stress is applied to each circuit component and the load constituting the power supply, so that the power supply and the load are not provided. The life and reliability of the device. In addition, if each circuit component of the power supply is designed to withstand a rush current,
There has been a problem that the use of circuit components larger than the normal rating increases the size of the device and increases the cost.

Furthermore, when a rush current flows through the power supply, the voltage of the commercial power supply (AC outlet side) that supplies the commercial power supply voltage as the operating voltage to the power supply greatly fluctuates, and is driven simultaneously by the commercial power supply. In other electronic devices, for example, a lighting device, there is a problem that the lighting may be momentarily darkened or flickered due to a voltage change of a commercial power supply, or the power supply device itself may malfunction.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and it is an object of the present invention to provide a power supply device capable of suppressing an inrush current generated when driving a load whose impedance changes with temperature. With the goal.

[0007]

In order to achieve the above object, as a power supply device capable of supplying a drive voltage to a load whose impedance changes with temperature,
Temperature detection means for detecting the temperature of the load, and current control means capable of controlling a load current flowing through the load in accordance with the temperature detected by the temperature detection means, wherein the current control means The load current flowing through the load is controlled in accordance with the temperature detected by the temperature detecting means, so that the time until the voltage applied to the load reaches a predetermined load voltage is controlled.

Further, the current control means controls the load current flowing to the load when the power is off, and controls the time until a predetermined load voltage applied to the load becomes zero level.

According to the present invention, when the temperature of the load is detected to be low by the temperature detecting means, that is, when the impedance of the load is low, the load current flowing through the load is gradually increased to be applied to the load. The time required for the voltage to reach a predetermined load voltage is lengthened. That is,
When the impedance of the load is low, the inrush current flowing through the power supply device is suppressed by slowly increasing the load voltage applied to the load.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the power supply device of the present invention will be described below. FIG. 1 is a diagram illustrating a configuration example of a power supply device according to the present embodiment. In this FIG.
A commercial power supply voltage input from a commercial power supply 1 via an AC outlet (not shown) passes through a line filter (LFT) 2 and is input to the primary side of a rectifier circuit 4 via a fuse 3. The rectifier circuit 4 is configured by a bridge diode, performs full-wave rectification of the commercial power supply voltage input to the primary side, smoothes the rectified rectified current with a smoothing capacitor C1, and outputs a predetermined voltage V1. You.

The switching power supply circuit 5 enclosed by a broken line
For example, a switching element Q1 including a field effect transistor (FET), a diode D2, a capacitor C2,
And a choke coil L to constitute a step-down switching circuit. The cathode of the diode D2 is connected to the positive electrode of the rectifier circuit 4, and the anode is connected to the negative electrode of the rectifier circuit 4 via the switching element Q1. I have. Further, a capacitor C2 and a choke coil L connected in series are connected in parallel to the diode D2. In parallel with the capacitor C2 of the switching power supply circuit 5, for example, an incandescent lamp 10
Etc. will be connected.

In such a switching power supply circuit 5, when the switching element Q1 is on, the diode D2 becomes non-conductive, and the output voltage V1 on the secondary side of the rectifier circuit 4 is supplied to the switching power supply circuit 5, and this output is output. The lamp current IL flows through the incandescent lamp 10 and the choke coil L by the voltage V1. On the other hand, when the switching element Q1 is off, a back electromotive force is generated in the choke coil L in order to maintain the lamp current IL flowing through the choke coil L, and thereby the diode D2 conducts, and the incandescent lamp 10 and The lamp current IL flows through the choke coil L. Therefore, the lamp current IL flowing through the incandescent lamp 10
Means that a current corresponding to the on / off period of the switching element Q1 flows.

The incandescent lamp 10 has a characteristic that its impedance changes depending on the temperature. For example, when the temperature is low, the impedance is low, and as the temperature rises, the impedance increases.

The temperature sensor 6 includes, for example, an incandescent lamp 10.
Is a non-contact type temperature sensor that is disposed, for example, near the incandescent lamp 10 and can detect the temperature of the incandescent lamp 10. The temperature sensor is, for example, a thermistor, a resistance thermometer,
A contact-type temperature sensor using a pn junction semiconductor, a thermocouple, or the like may be used.

The control circuit 7 performs on / off control of the switching element Q1 of the switching power supply circuit 5, and includes, for example, a pulse generator capable of generating a control pulse P for turning on / off the switching element Q1. Provided. When the switch S1 is turned on, based on the temperature of the incandescent lamp 10 detected by the temperature sensor 6, the switching Q1 is changed while changing the time constant of the pulse generator, that is, while changing the pulse width of the control pulse P. It is turned on / off.

The switch S1 is turned on / off by a user, or is turned on in conjunction with a main power switch of an electronic device having a power supply device according to the present embodiment which is turned on / off by a user. / Off controlled. The switch S1 is not limited to a mere contact switch.
It is also possible to configure by a photocoupler 21 composed of a light emitting element and a light receiving element as shown in (a) or a relay switch 22 as shown in FIG.

Hereinafter, the operation of the power supply device of the present embodiment as described above will be described with reference to FIGS.
Control circuit 7 of power supply device according to the present embodiment
When the switch S1 is turned on, the temperature of the incandescent lamp 10 is detected by the temperature sensor 6, and based on the temperature detection result, the pulse width of the control pulse P for controlling on / off of the switch element Q1 is varied. Output.

For example, the control circuit 7 is shown in FIG.
When the switch S1 is turned on as shown in FIG. 3 and the temperature of the incandescent lamp 10 is determined to be low based on the temperature detection result from the temperature sensor 6, the switching element Q1 is turned on / off as shown in FIG. The on-time of the switching element Q1 is gradually increased by gradually increasing the pulse width of the control pulse P to be turned on. That is, when the temperature of the incandescent lamp 10 is low, the lamp current IL flowing through the incandescent lamp 10 is gradually increased, and as shown in FIG. The voltage rises to the voltage VL.

When the temperature of the incandescent lamp 10 is high, the control circuit 7 switches the switch S1 (not shown).
Is turned on, the pulse width of the control pulse P for controlling on / off of the switching element Q1 is quickly controlled to a predetermined pulse width, and when the temperature of the incandescent lamp 10 is low as described above, Thus, the lamp terminal voltage of the incandescent lamp 10 rises to the predetermined voltage VL in a relatively short time.

As described above, in the power supply device according to the present embodiment, the control circuit 7 detects the temperature of the incandescent lamp 10 when the switch S1 is turned on, and based on the temperature detection result, that is, the incandescent lamp 10 Is controlled until the terminal voltage of the incandescent lamp 10 reaches the predetermined voltage VL.

FIG. 4 shows the voltage waveforms of the lamp terminal voltage supplied to the incandescent lamp 10 from the power supply according to the present embodiment and the lamp terminal voltage supplied to the incandescent lamp 10 from the conventional power supply. FIG. This figure 4
The voltage waveform shown by the broken line in FIG. 3 shows the lamp terminal voltage characteristics of the conventional power supply device.
The voltage waveforms indicated by are graphs respectively showing the lamp terminal voltage characteristics of the power supply device according to the present embodiment.

As can be seen from FIG. 4, the lamp terminal voltages supplied from the power supply device according to the present embodiment to the incandescent lamp 10 reach the predetermined voltages VL, respectively, times t2 and t1. Is designed so that the lamp terminal voltage supplied to the incandescent lamp 10 from the conventional power supply device is longer than a time t0 until the lamp terminal voltage reaches a predetermined voltage VL.

The power supply device according to the present embodiment is:
When the impedance of the incandescent lamp 10 when it is turned on is larger than the above case, as shown by the solid line, the time (t1) from when it is turned on until the lamp voltage of the incandescent lamp 10 reaches the predetermined voltage VL is , The solid line time (t
2) shorter. That is, when the impedance of the incandescent lamp 10 is large, the lamp terminal voltage is quickly raised to the predetermined voltage VL.

Also, in this embodiment, when the switch S1 is turned off, the lamp terminal voltage VL does not drop to 0V at the instant t4 as in the conventional power supply device, but gradually over a predetermined time (t3), for example. The voltage VL is dropped to 0V. As described above, when the switch S1 is turned off, the lamp terminal voltage VL supplied from the power supply device to the incandescent lamp 10 does not instantaneously fall, but the voltage is gradually decreased, thereby reducing the power supply. When the power supply is turned off, it is possible to prevent the occurrence of a so-called voltage flicker in which the voltage of the commercial power supply 1 that supplies the commercial power supply voltage to the electric device greatly fluctuates.

In this embodiment, the incandescent lamp 1 is used as a load whose impedance changes with temperature.
Although 0 has been described as an example, it is needless to say that the present invention is not limited to this and can be applied to, for example, driving a heater or the like.

[0026]

As described above, when the power supply is turned on, when the temperature of the load is detected to be low by the temperature detection means, that is, when the impedance of the load is small, the power supply apparatus of the present invention is controlled by the current control means. By gradually supplying a large load current to the load, it is possible to prolong the time until the load reaches a predetermined load voltage and suppress the inrush current flowing through the power supply device. As a result, normal rated components can be used for the circuit components constituting the power supply device, so that the power supply device can be reduced in size and weight,
And cost reduction can be realized.

Further, the power supply device of the present invention suppresses the rush current, thereby reducing the stress on each circuit component and the load of the power supply device. Can be realized. Furthermore,
Since the voltage fluctuation of the commercial power supply can be reduced, there is no adverse effect on other electronic devices connected to the commercial power supply at the same time.

Also, the present invention controls the current flowing to the load when the power is turned off, and extends the time until the voltage applied to the load reaches the zero level. Voltage fluctuation of the power supply can be prevented.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration example of a power supply device according to an embodiment of the present invention.

FIG. 2 is a diagram showing another configuration example of the switch.

FIG. 3 is a diagram illustrating output waveforms of respective circuit units of the power supply device according to the present embodiment.

FIG. 4 is a diagram showing a waveform of a lamp terminal voltage output from the power supply device according to the present embodiment.

[Explanation of symbols]

1 commercial power supply voltage, 2 line filter, 3 fuse, 4 rectifier circuit, 5 switching power supply circuit, 6 temperature sensor, 7 control circuit, 10 incandescent lamp,

Claims (2)

[Claims] 1. A power supply device capable of supplying a drive voltage to a load whose impedance changes with temperature, comprising: a temperature detecting means for detecting a temperature of the load; and a temperature detecting means for detecting a temperature detected by the temperature detecting means. Current control means capable of controlling a load current flowing through the load in response to the temperature detected by the temperature detection means when the power is turned on. A power supply device, wherein a current is controlled to control a time until a voltage applied to the load reaches a predetermined load voltage. 2. The power supply according to claim 1, wherein the current control means controls a load current flowing through the load when a power supply is turned off, and controls a time until a predetermined load voltage applied to the load becomes a zero level. The power supply device according to claim 1, wherein: