JPH01218355A - Switching power supply - Google Patents

Abstract

PURPOSE:To miniaturize and lighten an apparatus by using the transformer secondary winding of a choke converter circuit as a choke coil. CONSTITUTION:A switching power circuit is composed of the primary winding 2 and output winding 3 of a choke converter transformer, a switching transistor(Tr) 1, a rectifier diode 6, a smoothing capacitor 7, an output voltage detector circuit 8, a choke converter control circuit 9, a synchronizing signal winding 5, a chopper circuit Tr 11, an output detector circuit 14, a comparison and control circuit 15 and others. In this case, a part of winding 4 of said transformer is used as a choke coil for a secondary side chopper circuit. Thus, it is possible to eliminate the choke coil of a chopper type switching circuit so that an apparatus decreases in cost and is miniaturized and lightened.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention does not only use a choke converter transformer as a transformer as in the past (but also uses its inductance as a choke coil in a chopper circuit provided on the secondary side). This relates to a switching power supply used as a power supply.

Conventional technology In switching power supplies that require multiple different stabilized outputs, there is generally an output circuit that detects the output voltage and controls a ringing choke converter (RCC), etc., although this varies depending on various conditions and design concepts. , a plurality of different outputs are often obtained by configuring a chopper type switching circuit that uses the output voltage as the input voltage.

Figure 3 shows an example of a switching power supply circuit that has been commonly used in the past, with 37 being a switching transistor;
38 is the primary winding of the choke converter transformer, 39 is the secondary winding of the same transformer, 40 is the rectifier diode, 41
42 is a smoothing capacitor, 42 is an output voltage detection circuit, 43 is a control circuit, and the circuit within the 0-dot line that stabilizes the voltage at the output terminal 51 is a chopper type switching circuit, 44 is a switching transistor, 45 is a resistor, 46 is a is a commutating diode, 48 is a choke coil, 47 is a smoothing capacitor, 49 is an output detection circuit, 50 is a control circuit, 52 is an output terminal, and 53 is a connection point for the primary winding 38 of the choke converter transformer. .

Problems to be Solved by the Invention The above-mentioned chopper-type switching circuit requires a choke coil 48, and the output current to be taken out is thick (as the output current becomes larger, the choke coil 48 also becomes larger, so a smaller and lighter design is required. There was a problem in that not only was there a problem in doing so, but the cost was also high.

Means for Solving the Problems The present invention solves the above-mentioned problems.In a switching power supply using a choke converter transformer circuit system, in a switching power supply using a ringing type or flyback type choke converter circuit system, the present invention solves the above problems. This is a switching power supply characterized in that a part of the transformer of the circuit is used as a choke coil of a chopper circuit on the secondary side. And when the inverter is ON, O
A winding is provided on the secondary side so that the ON current flows in the same direction as the winding direction of the primary winding, and this winding is used as a choke coil in a chopper type switching circuit. This is a switching power supply characterized by stabilizing the output voltage by synchronizing and controlling the ON time with an inverter.

By using the secondary winding of the transformer of the functional choke converter circuit as a choke coil, the choke coil of the chopper type switching circuit can be eliminated, reducing cost, size, and weight. Since a periodic current flows through the primary winding, the energy in the primary winding can be reduced by the amount of energy stored in this winding, so it has the effect of increasing the efficiency of the power supply compared to conventional systems.

EXAMPLES Hereinafter, the present invention will be explained with reference to examples shown in FIGS. 1 and 2.

Figures 1 and 2 are switching power supply circuits that are exactly the same, with the difference that the switching transistor of the chopper circuit is placed before or after the transformer winding for the choke coil.

1 and 2, 2.20 is the primary winding of the choke converter transformer, 1.19 is the switching transistor, 3.21 is the output winding of the choke converter transformer, 6.24 is the rectifier diode, and 7. 25 is a smoothing capacitor, 8.26 is an output voltage detection circuit, 9.27
is a choke converter control circuit, 4.22 is a winding according to the present invention, 5.23 is a synchronous signal winding, 10.28 is a reverse voltage prevention diode (may be unnecessary), 11.29
is the switching transistor of the chopper circuit, 12.
30 is a resistor, 13.31 is a smoothing capacitor, 14.
32 is an output detection circuit, 15.33 is a comparison control circuit, 16
．． 34, 17, and 35 are output terminals, and 18.36 is a connection point of the primary winding 2.20.

Next, the principle of operation of the present invention will be explained with reference to FIG.

Since the winding direction of the winding 15 and the primary winding 2 are the same, when the switching transistor 1 is turned on, an ON signal synchronized with this is generated in the synchronous signal winding 5, and the transistor 11 is turned on via the comparison control circuit 15. let transistor 11
When turned ON, current flows from the smoothing capacitor 7 of the output terminal 16 to the capacitor 13 through the winding 4. The current waveform flowing at this time is similar to the current waveform flowing through the choke input type smoothing circuit due to the inductance of the transformer, and is similar to and synchronized with the primary winding current waveform.

Further, the ON time of the transistor 11 is comparatively controlled to stabilize the output voltage of the chopper circuit, and therefore is shorter than the ON time of the inverter of the choke converter transformer circuit. This situation is shown in FIG. 4, which shows the current waveform and voltage waveform of each winding during the switching operation. In FIG. 4, A is a current waveform flowing in the winding 2, B is a current waveform flowing in the winding 3, C is a current waveform flowing in the winding 4, and D is a voltage waveform induced in the winding 5.

As can be inferred from the operating waveforms in Figure 4, the sum of the energy stored in the primary winding 2 and winding 4 during the inverter's ON time is released as energy to the output winding 3 during the inverter's OFF time. Therefore, in order to extract the same amount of energy to the output winding 3, the switching power supply of the present invention suppresses the energy (current) of the primary winding NiA2 by the energy of the winding 4 than the conventional switching power supply. This will increase the efficiency of the power supply.

In addition, although the above-mentioned embodiment explained the case where there is one chopper circuit, a plurality of chopper circuits can be designed using the same concept. Further, although a transistor is used as a switching element here, an FET may be used instead. Furthermore, although the kite is provided with a winding 5 or 23 for synchronizing the oscillation frequency of the inverter, the winding 3 or 21 can also be used to generate a synchronizing signal.

Effects of the Invention As described above, the switching power supply of the present invention uses the choke converter circuit type transformer as the choke coil of the chopper circuit on the secondary side, so the choke coil used conventionally can be eliminated. It has remarkable effects such as being able to reduce costs, reduce size and weight, and improve power supply efficiency, and has great industrial and practical value.

[Brief explanation of the drawing]

Figures 1 and 2 are circuit explanatory diagrams of the main parts of the switching power supply of the present invention, Figure 3 is a circuit diagram of the main parts of a conventional switching power supply, and Figure 4 is a current and voltage diagram of each part of the switching power supply. FIG. 1111.19.29 Niswitching transistor 2.
20: Primary winding 3.21: Output winding 4.22: Winding
5.23: Synchronous signal winding 6.24: Rectifier diode 7.25.13.31: Smoothing capacitor 8.26: Output voltage detection circuit 9.2'? ? Control circuit 10.28: Reverse breakdown voltage prevention diode 12.30: Resistor 14.32: Output detection circuit 15.
33: Comparison control circuit

Claims (1)

[Claims] A switching power supply of a ringing type or a flyback type choke converter circuit type, characterized in that a part of a transformer of the choke converter circuit is used as a choke coil of a secondary side chopper circuit.