JPH03215164A - Switching 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 relates to a switching power supply device using a primary side control method used in each electronic device.

2. Description of the Related Art The startup and disconnection of a conventional switching power supply device are shown in FIGS. 4 and 6. The configuration was as shown in FIG.

In Fig. 4, a switch 4 and the primary winding (Ilsa) of a switching transformer 6 and a switching element 2 are connected to the input power supply 1 via a switch 4, and the connection between the switch 4 and the primary winding iaa of the switching transformer 6 is activated. A rectifying and smoothing circuit is connected to the base of the switching element 2 via the resistor 3 and to the bias winding 6Qf of the transformer 6 via the base resistor 5, and is connected to the secondary winding 6b of the switching transformer 6 by a rectifying and smoothing circuit consisting of a diode 7 and a capacitor 8. It is configured by fully connecting.

By turning on the switch 4, a voltage is applied to the base of the switching element 2 via the starting resistor 3, turning on the switching element 2 and turning on the primary winding 6a of the switching transformer 6.
A voltage V, which is proportional to the primary winding θ& of the switching transformer 6, is generated also in the bias winding 6C. is generated and the switching element 2 is driven. FIG. 6 shows an example in which the switching element 2 is driven by the control IC 9, and the bias winding 6C has a diode 10 and a capacitor 11.
A power supply for the control 109 is configured by connecting a rectifier qz clearing circuit.

FIG. 6 shows a control IC 9 provided with a remote circuit 12, which is a circuit that starts and stops activation by opening and closing a switch 13.

Problems to be Solved by the Invention In the circuits shown in FIGS. 4 and 6, since the switch 4 is used to directly open and close the input power source 1, the capacity of the switch 4 is large and the cost is high.

Also, Figure 4. Figure 5. In FIG. 6, after starting, power is supplied from the starting resistor 3, resulting in large losses and poor efficiency. In FIG. 6, it is necessary to provide the remote circuit 12 in the control IC 9, which increases the cost.

The present invention eliminates the above-mentioned conventional drawbacks, reduces cost,
The purpose is to provide a highly efficient switching power supply device.

Means for Solving the Problems In order to solve the above problems, the present invention connects the primary winding of a switching transformer to an input power source via a switching element, and connects the primary winding of a switching transformer to an input power source via a starting resistor at both ends of the input power source. Connect the start/stop switch, connect the movable terminal of the start/stop switch to the base or gate of the switching element, connect the bias winding of the switching transformer, and apply rectification to the secondary winding of the switching transformer. It has a configuration in which moseal circuits are connected.

Further, the control XCf is connected to the base or gate side of the switching element, and the bias winding of the switching transformer is smoothed and connected to the control IC.

Effect: With the circuit configuration described above, after startup, the startup start/stop switch is in an open state and no current flows through the startup resistor, resulting in high efficiency.

Further, by providing a start/stop switch in the low voltage section connected to the input power source via a starting resistor, it is possible to make the switch small in capacity and low in cost.

Example Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram of a switching power supply device according to an embodiment of the present invention. In Fig. 1, 16 is the input power supply, 1
7 is a switching element made of a transistor, 18 is a starting resistor, 19 is a starting start/stop switch, 2o is a base resistor, 21 is a primary winding of a switching transformer 29, 2
2 is a bias winding of the switching transformer 29, 26 is a secondary winding of the switching transformer 29, 27 is a rectifier diode, and 28 is a moss capacitor.

The operation of the present invention will be explained below.

In FIG. 1, at the time of start-up, the terminal of the start/stop switch 19 is connected to a, and the power of the input power source 16 is applied to the base or gate of the switching element 17 via the start-up resistor 18, and the switching element 17 is turned on. Turn it on. When the switching element 17 is turned on, a voltage Vp is generated in the primary winding 21 of the switching transformer 29, and a voltage Vp is generated in the primary winding 21 of the switching transformer 29.
, electric field vB is generated in the secondary winding 26 of the switching transformer 29 and drives the switching element 17 through the base resistor 2o, and electric field VB is generated in the secondary winding 26 of the switching transformer 29. The rectifier diode 27 and smoothing capacitor 28 perform bv smoothing.

After startup, the startup start/stop switch 19 is in an open state, and the noise winding 2 of the switching transformer 29 is
The oscillation of the switching element 17 continues due to the electric current EVB from 2.

When stopped, by connecting the contact point of the start/stop switch 19 to b, the voltage FEVB'! of the bias winding 2o is reduced. r
It is lowered and the switching element 17 is turned off (the activation start/stop switch 19 is of an automatic return type and is open when not operated) to stop the operation.

FIG. 3 shows an example in which a control IC 25 is used, and the operation is the same as that shown in FIG. 18 to the control IC 25, and the control IC 25i
The switching element 17 is turned on, and a voltage V.
is generated and the voltage V. The IP is smoothed by the rectifier diode 23 and the mole capacitor 24, and the voltage is controlled by the IC 25.
is driven to cause the switching element 17 to oscillate and generate a voltage Vs in the secondary winding 26 of the switching transformer 29,
Rectifier diode 27. A smoothing capacitor 28 performs smoothing.

When stopped, 'KE Y!' of bias winding 2o of switching transformer 29 is connected to contact Ib of start/stop switch 19. By lowering le, the control IC 25 is stopped and the nulling element 17 is turned off, thereby starting and stopping.

Further, Fig. 2 a and b show an example in which the start/stop operation described above is performed using the signals A and H by configuring the start/stop switch 19 of Figs. 1 and 3 and a semiconductor switch. FIG. 2a shows a device using two transistors, and FIG. 2b shows a device using two field effect transistors.

Effects of the Invention As described above, the start/stop circuit of the switching power supply according to the present invention has a very simple circuit configuration, which enables the overall miniaturization, cost reduction, and high efficiency, and has practical value. It is a dog.

[Brief explanation of drawings]

Figure 1. FIG. 3 is an electrical circuit diagram showing an embodiment of the switching power supply device of the present invention, FIGS. 2a and 2b are electrical circuit diagrams of an embodiment in which a semiconductor switch is used as the start/stop switch, and FIG. Figure, Figure 5. FIG. 6 is an electrical circuit diagram of a conventional example. 16...Input power supply, 17...Switching element, 18...Starting resistor, 19...
Starting start/stop switch, 20...Base resistance, 21...Primary winding of switching transformer,
22...Bias winding of switching transformer,
23... Rectifier diode, 24... Smoothing condenser, 26... Control IC, 28...
・Secondary winding of switching transformer, 27...
Rectifier diode, 28... Mosquito capacitor, 2
9...Switching transformer.

Claims (2)

[Claims] (1) Connect the primary winding of the switching transformer to the input power source via a switching element, connect a startup start/stop switch to both ends of this input power source via a startup resistor, and connect the base or gate of the switching element to the primary winding of the switching transformer. A switching power supply device comprising: a movable terminal of the start/stop switch connected to the bias winding of the switching transformer; and a rectifier and smoothing circuit connected to the secondary winding of the switching transformer. (2) Control I on the base or gate side of the switching element
2. The switching power supply device according to claim 1, wherein the bias winding of the switching transformer is smoothed and connected to the control IC.