JPH083196Y2 - Switching power supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a step-up type switching power supply device having a reactor.

[Prior Art] FIG. 3 shows a conventional switching power supply device including a boosting reactor and an insulating transformer. This switching power supply device includes an inverter circuit 3 connected between one end and the other end of a DC power supply 1 via a boosting reactor 2, and a rectifying / smoothing circuit 4 connected to an output terminal of the inverter circuit 3. It comprises a load 5 connected to this, and a surge absorbing capacitor 8 connected via a resistor 7 between the output terminal of the reactor 2 and the other end (ground) of the power source 1.

The inverter circuit 3 comprises first, second, third and terminal transistors Q1, Q2, Q3, Q4 as bridge-connected switching elements, control circuits 6 for these, and an insulating transformer T. The primary winding N1 of the transformer T is connected between the emitter of the transistor Q1 and the emitter of the transistor Q3. The secondary winding N2 is connected to the load 5 via the rectifying / smoothing circuit 4. The rectifying / smoothing circuit 4 includes a bridge rectifying circuit including four diodes D1 to D4 and a smoothing capacitor C.

When operating this switching power supply, first, the four transistors Q1 to Q4 are simultaneously turned on. As a result, a current flows through the boosting reactor 2 and energy is accumulated there. Next, the first transistor Q1 is turned on, the second transistor Q2 is turned off, and the third transistor Q2 is turned on.
It controls Q3 to be off and the fourth transistor Q4 to be on. As a result, the boosting reactor 2 is connected to the rectifying / smoothing circuit 4 via the transformer T, and the sum voltage of the power supply voltage and the voltage of the reactor 2 is applied to the capacitor C via the transformer T. Next, again the first to fourth transistors Q1 to Q4
Are simultaneously turned on, and energy is accumulated in the boosting reactor 2. Then, the second and third transistors Q2,
Q3 is turned on, the first and fourth transistors Q1 and Q4 are turned off, and the sum voltage of the power supply voltage and the voltage of the boosting reactor 2 is applied to the capacitor C via the transformer T.

[Problems to be Solved by the Invention] Since the capacitor 8 is connected between the input terminals of the inverter circuit 3 via the resistor 7, the surge voltage generated when the transistors Q1 to Q4 are turned off is absorbed by the capacitor 8. However, the discharging of the capacitor 8 causes a power loss in the resistor 7.

On the other hand, multiple power supplies may be required. In this case, providing a plurality of power supply circuits independently increases the cost.

Therefore, an object of the present invention is to provide a switching power supply device that can reduce power loss and can obtain a plurality of voltages.

[Means for Solving the Problems] The present invention for achieving the above object includes a DC power supply for supplying a DC voltage, a boosting reactor having one end connected to one end of the DC power supply, and the boosting reactor. At least 2 connected between the reactor and the other end of the DC power supply
An inverter circuit including two switching elements and a transformer, a rectifying / smoothing circuit connected to the inverter circuit, one end connected to the other end of the boosting reactor, and the other end connected to the other end of the DC power supply. Capacitor, a reverse current blocking diode connected in series with the capacitor, an auxiliary power supply circuit connected in parallel with the capacitor, the other end of the boosting reactor and the other end of the DC power supply are short-circuited. And a period in which the at least two switching elements of the inverter circuit are simultaneously controlled to be in an ON state so that energy is stored in the boosting reactor and the at least two switching elements are alternately turned on so that the inverter circuit operates as an inverter. .Providing a control circuit for controlling the inverter circuit so as to have a turning-off period And wherein between the step-up reactor and the inverter circuit in which according to the step-up type switching power supply apparatus characterized by not surge absorption circuit is provided.

[Operation and Effect of the Invention] In the present invention, instead of providing a surge absorbing circuit between the boosting reactor and the inverter circuit, a capacitor is connected through a reverse current blocking diode and the energy of this capacitor is consumed. The auxiliary power circuit is connected to. Therefore, the energy absorbed by the capacitor can be consumed by the auxiliary power supply circuit without being consumed by the resistor. As a result, the efficiency of the power supply device can be improved.

[First Embodiment] Next, a switching power supply device according to a first embodiment of the present invention will be described with reference to FIG. However, in FIG.
The same parts as those in FIG. 3 are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, a capacitor 10 is connected between the output side terminal of the reactor 2 and the other end (ground) of the power supply 1 via a diode 9, and the auxiliary power supply circuit is connected in parallel with the capacitor 10.
11 is connected.

The auxiliary power supply circuit 11 includes a switching element 14 connected between one end and the other end of a capacitor 10 via a primary winding 13 of a transformer 12, an on / off control circuit 15, and a transformer.
A rectifying / smoothing circuit 21 including diodes 17, 18 connected to a secondary winding 16 of 12, a reactor 19, and a capacitor 20 is provided, and supplies a constant voltage to a load 22. The load 22 may be the control circuit 6 of the inverter circuit 3. That is, the auxiliary power supply circuit 11 may be used as the power supply for the control circuit 6.

With this configuration, the surge voltage generated when the transistors Q1 to Q4 as switching elements of the inverter circuit 3 are turned off is absorbed by the capacitor 10, and the energy of the capacitor 10 is transferred to the load 22 via the auxiliary power supply circuit 11. Is released. Therefore, power loss due to discharge of the capacitor 10 does not occur. Further, the power factor is improved by providing the capacitor 10.

Second Embodiment Next, a step-up switching power supply device according to the second embodiment will be described with reference to FIG. However, parts common to those in FIGS. 1 and 3 are designated by the same reference numerals, and description thereof will be omitted.

In this embodiment, a parallel inverter circuit 3 is connected between the boosting reactor 2 and the lower end of the power supply 1. The inverter circuit 3 includes first and second transistors Q1 and Q2 as switching elements, a transformer T, and a control circuit 6
It consists of and. The center tap of the primary winding N1 of the transformer T is connected to the output terminal of the boosting reactor 2 and is connected to the primary winding N1.
The first and second transistors Q1 and Q2 are connected between both ends of and the lower end of the power source 1, respectively. The secondary winding N2 also has a center tap, and is connected to the load 5 via a rectifying / smoothing circuit 4 including two rectifying diodes D1 and D2 and a smoothing capacitor C.

When operating this switching power supply device, first, the first and second transistors Q1 and Q2 are simultaneously turned on. As a result, energy is stored in the boosting reactor 2. Next, the first transistor Q1 is turned on and the second transistor Q2 is turned off. As a result, the primary winding N1
A voltage obtained by adding the voltage of the reactor 2 to the power supply voltage is applied to the upper half, and a voltage corresponding to this is obtained at the secondary winding N2. Next, the first and second transistors Q1 and Q2 are simultaneously turned on again to accumulate energy in the reactor 2.
Next, the second transistor Q2 is controlled to be turned on and the first transistor Q1 is controlled to be turned off. As a result, a voltage obtained by adding the voltage of the reactor 2 to the voltage of the power source 1 is applied to the lower half of the primary winding N1, and a voltage in the opposite direction to the previous direction is obtained at the secondary winding N2.

The functions of the capacitor 10 and the auxiliary power supply circuit 11 are the same as those in the first embodiment, and the same effects can be obtained.

[Modification] The present invention is not limited to the above-described embodiments, and includes, for example, an inverter circuit 3, a rectifying / smoothing circuit 4, and an auxiliary power supply circuit.
The configuration such as 11 can be variously modified.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a switching power supply device according to a first embodiment of the present invention, FIG. 2 is a circuit diagram showing a switching power supply device according to the second embodiment, and FIG. 3 is a conventional switching power supply device. It is a circuit diagram. 1 ... Power supply, 2 ... Reactor, 3 ... Inverter circuit, 4 ... Rectifying and smoothing circuit, 9 ... Diode, 10 ... Capacitor, 11 ... Auxiliary power supply circuit.

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H02M 3/337 CD

Claims (1)

[Scope of utility model registration request] 1. A DC power supply for supplying a DC voltage, a boosting reactor having one end connected to one end of the DC power supply, and a boosting reactor connected between the boosting reactor and the other end of the DC power supply. An inverter circuit including at least two switching elements and a transformer, a rectifying / smoothing circuit connected to the inverter circuit, one end connected to the other end of the boosting reactor, and the other end of the DC power supply. A reverse current blocking diode connected in series with the capacitor, an auxiliary power supply circuit connected in parallel with the capacitor, the other end of the boosting reactor and the other end of the DC power supply. The at least two switching elements of the inverter circuit are simultaneously turned on so as to short-circuit and store energy in the boosting reactor. A control circuit for controlling the inverter circuit so as to have a control period and a period in which the at least two switching elements are alternately turned on and off so that the inverter circuit operates as an inverter. A boosting type switching power supply device characterized in that a surge absorption circuit is not provided between the inverter circuit and the inverter circuit.