JPS6277824A - Power source - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is applicable to motors that require a relatively large current only for a short period of time, such as a motor that requires a large current instantaneously when starting. relates to a power supply device suitable for powering loads that draw relatively small currents.

[Conventional technology]

Conventionally, motor dividing devices have been designed to have a large capacity so that a large current can be supplied during startup. It is also possible to design the power supply to have a relatively small capacity so that when a large current continues to flow for a predetermined period of time that exceeds the motor starting time, the power supply device will be inoperable or the load circuit will be cut off. ing.

[Problem that the invention seeks to solve]

Shikijina 71'-etc., those designed for large capacity are usually σ
) It is wasteful and the efficiency of the power supply device is poor for 9 units of operation.

Additionally, devices that detect when a large current continues to flow for a predetermined period of time can improve the efficiency of the power supply, but even if an excessive current flows, such as when a load short circuit occurs, Since the power supply device will not be rendered inoperable or one circuit will not be cut off until this period has elapsed, there is a risk that the components of the power supply device or the load may be destroyed by short-circuit current or the like.

The present invention has been made to solve the problems of the prior art, and can be provided at low cost with a small capacity.Moreover, a relatively large current may flow for a long time, or an excessive short circuit current may cause the permissible time to exceed the allowable time. The purpose of this invention is to provide a power supply device that can protect its components and loads by preventing them from flowing beyond their limits.

[Means for solving problems]

The present invention provides an AC power source whose output can be controlled, a rectifier that rectifies the output of the AC power source, a smoothing capacitor provided on the output side of the rectifier, and a connection between the rectifier and the smoothing capacitor. an interposed inductor, a flywheel diode provided in association with the inductor, and a current detection device provided on the output side of the inductor to reduce the output of the AC power supply when the current to the load is excessive; The inductor is unsaturated when a relatively small current normally required by the load flows through the inductor, and saturated when a relatively large current required by the load during startup, etc. flows for more than a predetermined time. 8 [Function] The present invention provides a known power supply device including a combination of a rectifier, a smoothing capacitor, an inductor, and a flywheel diode, in which the inductor is formed as described above. Since it is particularly special and is combined with a current detection device, it is possible to pass a relatively large current required by the load for a predetermined period of time. If the predetermined time is exceeded, the inductor will become saturated and a current exceeding the above-mentioned relatively large current will flow, and the current detection device will operate and reduce the output of the AC power supply, resulting in damage to components and the load. This is something that can be prevented from happening. When excessive current flows, such as when a load is short-circuited, the current detection device is activated regardless of whether the inductor force is saturated or unsaturated. Because the inductor is unsaturated for the relatively small blood flow normally required by the load, *
The flow sensing device is inactive.

The predetermined time can be determined depending on the load. For example, the load is a motor.

When the relatively large current value required for starting is about 10 times the relatively small current value during normal operation and is necessary for a period of 10 to 100 m5ec, the relatively large current is about 10 to 100 m5ec.
] The inductor may be formed so that the inductor is saturated when the inductor continuously flows for a period of time equal to or greater than OOm5ec and less than the allowable time of the component parts.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. (1) is one in which the output can be controlled by an AC power supply. In this embodiment, the device includes a switching transistor (2), a transformer (3) supplied with the switching output of this transistor, and a control device (4) that controls switching of the transistor (2). It is. The control device (4) is capable of changing the switching frequency and on-period, and any known device can be used. (5) is a rectifier, and (6) is a smoothing capacitor. (7) is an inductor, which is interposed between the rectifier (5) and the smoothing capacitor (6). This inductor (7) is.

When a load (8), which will be described later, passes a relatively large current that is required only for a short period of time, such as during startup, and continues to flow for more than a predetermined time, the load (8) becomes saturated, and the relatively small current that the load (8) normally requires is saturated. It is formed so that it is unsaturated when current is passed through it. Such an inductor (the force is e.g. E
It can be formed using an l-shaped or drum-shaped cafelite core. (9) is a diode for the flywheel,
This is for supplying the stored energy of the inductor (7) to the load (8)K. (101 is a current detection device,
Provided on the output side of the inductor (7) and connected to the load (
The output of the AC power source (1) is reduced when the current flowing to the AC power source (1) is excessive.

This embodiment includes a current detection resistor Uυ, a transistor α2 whose conduction is controlled according to the voltage across the resistor Uυ, and an integrating circuit O:3 provided on the output side of the transistor 121. The integration circuit (13
), the control device (4) of the AC power source (1)
It controls the That is, the output from the integrating circuit α is used to disable the control device (4) or to shorten the on-period of switching. The time constant of the integrating circuit (13) can be made as small as possible. This makes it possible to quickly reduce the output of the AC power source (1) when an overcurrent flows. I is a constant voltage means such as a dropper. The load (8) is, for example, a motor.

A current of 2.2A is required for 10 to 100rrLsec at startup.

During normal operation, a current of 0.3 A is required. The detection level of the current detection device CI is 3A.
The setting is such that the output of the AC power supply (1) is reduced when a current flows. (to) is another load (not shown).

). AC/DC converter for rectifying device (16)
, a smoothing capacitor (17), an inductor α second, and a flywheel diode 0, and further includes a voltage detection section (2) for negative feedback control. The voltage detection section (20
) controls the control device (4) of the AC power supply (11) according to the output signal.
) to stabilize the output voltage.

Next, the operation of this embodiment will be described. When starting the load (8), a relatively large current is required, and a current as shown in Figure 2 (al) flows through the inductor (7). (-For example, 10m5ec
), the load (8) will continue to require a large current, and the current of Figure 2 (al) will continue to flow through the inductor (7).
7) is a predetermined time (for example, 100 m5ec) in Figure 2 (a
When a current of l flows, self-heating occurs and the magnetic permeability of the core decreases.
This causes magnetic saturation and lowers the impedance. Therefore, the current flowing through the inductor (force) is shown in FIG. 2 (bl), and the current detection device (10) detects the overcurrent at this time and reduces the output of the AC power supply (1). Transistor (2) of AC power supply (1)
) and other components and loads (8).

When load (8) is operating normally.

As shown in Figure 2, only a current of 1 (cl) flows through the inductor (7).

Since the inductor (7) is not saturated, therefore.

The current detection device (10) also does not operate. At this time, the control device (4)
control wholesale.

Note that the seventh embodiment is not limited to the above embodiment, and various modifications are possible. For example, in addition to the above-mentioned embodiments, known AC power sources can be used as appropriate. Further, the inductor may be provided on the negative electrode side of the smoothing capacitor (6) in FIG. 1, and in this case,
The current detection device is provided on the power source side of the inductor. Also.

The present invention can be applied to any load other than the 9-load motor, such as a high-pressure discharge lamp, which requires a larger current than normal for a short period of time (when starting a high-pressure discharge lamp). .

〔Effect of the invention〕

As detailed above, the 'i-invention uses an inductor with special characteristics and combines it with a current detection device, so it can draw a larger current than normal for a predetermined time according to the load requirements. When a large current flows beyond the predetermined time or when an excessive current flows due to a load short circuit, the output is immediately reduced. Therefore, it is possible to provide a T-valve device that can be configured to have a small capacity and protect components and loads from overcurrent at low cost.

Moreover, since the inductor also serves as an inductor that stores energy and supplies it to the load side via the flywheel diode during periods when the input voltage from the power supply side is idle, the number of parts can be reduced by one. .

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing one embodiment of the present invention, and Fig. 2 is a circuit diagram showing an embodiment of the present invention.
FIG. 3 is a current waveform diagram showing the effect shown in FIG. (1)... AC power supply, (5)... curved rectifier. (6) Smoothing capacitor. (7)...Inductor, (8)...Bending load. (9)・・・Diode for flywheel.

Claims (2)

[Claims] (1) A power supply device that supplies power to a load that requires a relatively large current only for a short period of time and a relatively small current during normal times, and that includes an AC power supply whose output can be controlled, and an AC power supply whose output is controlled by the output of the AC power supply. A rectifier that rectifies, a smoothing capacitor provided on the output side of the rectifier, an inductor interposed between the rectifier and the smoothing capacitor, and a flywheel diode provided in association with the inductor. and a current detection device that is provided on the output side of the inductor and reduces the output of the AC power supply when the current to the load is excessive, and the inductor is provided with a relatively small current being supplied to the load. A power supply device characterized in that it is unsaturated when the current is present and becomes saturated when a relatively large current is supplied for a predetermined period of time. (2) The AC power supply includes a switching transistor, a transformer supplied with the switching output of the transistor, and a control device that controls switching of the transistor, and the control device changes the on period of the transistor. The power supply device according to claim (1), characterized in that it is possible.