JP2012010463A - Switching power supply apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a switching power supply apparatus with constant-current characteristics that has a structure in which an inductance of an inductor configuring a resonance circuit can be adjusted.SOLUTION: A switching power supply apparatus includes: a transformer 4 that supplies an output current of a switching power supply part 1 to a primary coil via a series resonance circuit 2 and a parallel resonance circuit 3; a rectifying and smoothing circuit 5 that rectifies and smooths an inductive voltage of a secondary coil of the transformer 4 to supply the rectified and smoothed inductive voltage to a load 8; a current detection part 6 that detects a current supplied from the rectifying and smoothing circuit 5 to the load 8, such as a relay apparatus for a submarine cable or the like; and a controller 7 that controls the switching power supply part 1 depending on a detection signal from the current detection part 6. An inductance of an inductor L2 connected in parallel to a capacitor C1 configuring the parallel resonance circuit 3 can be varied by adjusting a core gap to obtain desired resonance characteristics.

Description

  The present invention relates to a switching power supply device having a constant current characteristic that enables zero current switching by an LC resonance circuit.

  Various configurations of switching power supply devices are known. For example, a switching output current from a transistor is supplied to a primary winding of a full-wave rectifier circuit or a transformer via an LC series resonance circuit, and the output of the full-wave rectifier circuit is supplied. In a switching power supply device that supplies an output current obtained by rectifying a current or an induced voltage of a secondary winding of a transformer to a load, a second resonance frequency is set to be lower than a resonance frequency of the first LC resonance circuit. There is known a switching power supply device in which control characteristics are improved by providing the LC resonance circuit (see, for example, Patent Document 1). Also known is a switching power supply device in which an LC series resonance circuit and an LC parallel resonance circuit with a resonance frequency selected lower than the resonance frequency are connected in series to the switching circuit to enable switching control at a frequency higher than the audible frequency. (For example, refer to Patent Document 2).

  The long distance submarine cable relay device is installed at predetermined distances, and supplies the operating power of a plurality of relay devices in series from the land, and normally supplies constant current. It is known to apply a switching power supply device as a power supply device for that purpose. For example, as shown in FIG. 4, the switching power supply device having such a constant current characteristic includes a switching power supply unit 41 including a switching element such as a transistor, a resonance circuit 42, a transformer 44, a rectifying and smoothing circuit 45, a current The detection circuit 46 includes a detection unit 46, a control unit 47, and a load 48 such as a submarine cable relay device. The resonance circuit 42 is a composite resonance circuit including an inductor L11, a capacitor C11, and an inductor L12. The current from the power supply unit 41 flows to the primary winding of the transformer 44 via the resonance circuit 42, and the induced voltage of the secondary winding is supplied to the load 48 via the rectifying / smoothing circuit 45 and supplied to the load 48. The current detection unit 46 detects the current to be generated, and the control unit 47 is set based on the current detection value by the current detection unit 46 so that the predetermined current is set. Controlling the switching power supply unit 41.

  Regarding the resonance frequency ω1 of the series resonance circuit including the inductor L11 and the capacitor C11 of the resonance circuit 42 and the resonance frequency ω2 of the parallel resonance circuit including the capacitor C11 and the inductor L12, the resonance frequency ω1 of the series resonance circuit is the same as that of the parallel resonance circuit. Each component is selected so that the frequency is lower than 1/2 of the resonance frequency ω2. Accordingly, a configuration has been proposed in which the setting range of the current supplied to the load 48 can be widened and stabilized (see, for example, Patent Document 3).

Japanese Patent Laid-Open No. 56-112886 Japanese Patent Publication No. 6-97839 JP 2004-129462 A

  In the conventional example shown in FIG. 4, the capacitor C11 and the parallel resonance circuit are configured so as to have a resonance frequency other than an integral multiple of the resonance frequency of the inductor L11 and the capacitor C11 constituting the resonance circuit 42. The inductance of the inductor L12 is selected. For this purpose, the inductances of the inductors L11 and L12 and the capacitance of the capacitor C11 are selected so that a desired resonance frequency is obtained. Unlike the electronic parts of the above, since it is for electric power, it has a relatively large configuration and a relatively large deviation from the design value. Therefore, a product whose deviation is within an allowable range is adopted. For this reason, a relatively long time is required for the selection work, and unusable products remain, resulting in a problem of cost increase.

  An object of the present invention is to solve the above-described conventional problems, and to reduce the cost of a switching power supply device including a series resonant circuit and a parallel resonant circuit.

  The switching power supply device of the present invention includes a transformer that supplies an output current of a switching power supply unit to a primary winding through a series resonant circuit and a parallel resonant circuit, and rectifies and smoothes an induced voltage of the secondary winding of the transformer. A rectifying / smoothing circuit for supplying a load; a current detecting unit for detecting a current supplied from the rectifying / smoothing circuit to the load; and a control unit for controlling the switching power supply unit in accordance with a detection signal of the current detecting unit. In the switching power supply device, the inductor connected in parallel to the capacitor constituting the parallel resonant circuit is configured such that the inductance can be varied by adjusting the gap of the core.

  The inductor constituting the parallel resonant circuit includes an E-shaped core provided with a coil in a central core, an I-shaped core disposed opposite to the E-shaped core via a gap, and the E-shaped core capable of adjusting the gap. On the other hand, the I-shaped core is supported.

  The output current of the switching power supply unit is supplied to the primary winding of the transformer through a resonant circuit including a series resonant circuit and a parallel resonant circuit, and the induced voltage of the secondary winding is rectified and smoothed to provide a constant current to the load. Inductance of an inductor connected in parallel with a capacitor constituting a resonance circuit by making the gap adjustable in the core constituting the inductor of the parallel resonance circuit in the switching power supply that supplies power and making the inductance variable. Can be adjusted to a desired resonance frequency according to the capacitance of the capacitor, so there is no need to prepare a large number of inductors, and there is an advantage that the cost can be reduced.

It is explanatory drawing of Example 1 of this invention. It is principal part explanatory drawing of Example 1 of this invention. It is explanatory drawing of the inductor for comprising the parallel resonant circuit of Example 1 of this invention. It is explanatory drawing of a prior art example.

  The switching power supply device of the present invention will be described with reference to FIG. 1. A transformer 4 that supplies an output current of the switching power supply unit 1 to a primary winding via a series resonant circuit 2 and a parallel resonant circuit 3, and the transformer The rectifying / smoothing circuit 5 that rectifies and smoothes the induced voltage of the secondary winding 4 and supplies it to the load 8, the current detection unit 6 that detects the current supplied from the rectifying and smoothing circuit 5 to the load 8, and the current detection unit 6 is a switching power supply device including a control unit 7 that controls the switching power supply unit 1 in response to the detection signal 6, and the inductor L2 connected in parallel to the capacitor C1 constituting the parallel resonant circuit 3 is adjusted for the gap of the core Thus, the inductance can be varied, and a desired resonance characteristic can be obtained.

  FIG. 1 is an explanatory diagram of an embodiment of the present invention, in which 1 is a switching power supply unit including switching elements such as transistors, 2 is a series resonant circuit, 3 is a parallel resonant circuit, 4 is a transformer, 5 is a rectifying and smoothing circuit, Reference numeral 6 denotes a current detection unit, 7 denotes a control unit, 8 denotes a load such as a submarine cable relay device, C1 denotes a capacitor, L1 denotes an inductor constituting the series resonance circuit 2 with the capacitor C1, and L2 denotes a capacitor C1 in parallel. It is an inductor constituting the resonance circuit 3. Since the capacitor C1 constituting the series resonant circuit 2 and the parallel resonant circuit 3 is for electric power, it is impossible to make the capacitance variable. Therefore, the inductor L2 constituting the parallel resonant circuit 3 The inductance is adjustable. That is, a configuration in which the inductance can be changed by adjusting the air gap of the magnetic circuit configuring the inductor L2 is applied. The basic operation of the control for supplying the set current to the load 8 is substantially the same as the conventional example shown in FIG. 4, and the main part of the switching control in that case is shown in FIG.

  The switching power supply unit 1 shown in FIG. 2 includes transistors Q1 and Q2, a transformer T1, and a DC power supply E1, and the DC power supply E1 is a DC power supply obtained by rectifying and smoothing an AC voltage from a commercial AC power supply (not shown). The case is common. The transistors Q1 and Q2 are shown in a half-bridge connection configuration, but a full-bridge connection configuration can also be applied. These transistors Q1 and Q2 are alternately turned on and off by a control unit (not shown), whereby the current flowing in the primary winding of the transformer T1 is inverted, and the voltage induced in the secondary winding. Flows to the primary winding of the transformer T2 via the series resonant circuit 2 and the parallel resonant circuit 3. The induced voltage of the secondary winding of the transformer T2 is rectified by a full-wave rectifier circuit including diodes D1 to D4, smoothed by the capacitor C2, and supplied to a load (not shown). A smoothing circuit can be configured by the capacitor C2 and a smoothing inductor (not shown). Further, the current supplied to the load is detected by load current detection means (not shown), and the detection signal is input to a control unit (not shown), and the transistors Q1, Q2 are set to a predetermined value by the control unit. Switching control is performed.

  FIG. 3 is an explanatory diagram of the inductor L2 for constituting the parallel resonance circuit 3 with the capacitor C1 in FIGS. 1 and 2, 11 is a coil, 12 is a lead wire, 13 is an E-shaped core, 14 Is an I-shaped core, 15 and 16 are gap adjusting portions, 17 to 19 are support brackets, 20 is a mounting bracket, and G is a gap between the E-shaped core 13 and the I-shaped core 14. The E-shaped core 13 and the I-shaped core 14 are generally made of ferrite, and the coil 11 has a thickness corresponding to the current value supplied to the load, and the center core of the E-shaped core 13 (not shown). ) Insulated and fixed. Further, the I-shaped core 14 is supported by the support bracket 17 so as to face the E-shaped core 13, and the gap adjusting portion 15 is provided between both ends of the support bracket 17 and the support brackets 18, 19 at both ends of the E-shaped core 13. , 16 support. The inductor L2 is fixed to the power supply device by the mounting bracket 20.

  The gap adjusting portions 15 and 16 for adjusting the gap G between the E-shaped core 13 and the I-shaped core 14 are configured by bolts and nuts to reduce the gap G by tightening from above and below, and the inductance of the inductor L2 Is increased and loosened to increase the gap G to reduce the inductance of the inductor L2. After adjustment, the fixing nut is fixed with a fixing nut so as to maintain a desired gap G. As the configuration of the gap adjusting units 15 and 16, it is possible to apply components such as a position adjusting configuration in various mechanism units. Therefore, it is not necessary to measure the inductances of a plurality of inductors and select an inductor that forms a parallel resonant circuit, and a desired inductance can be obtained corresponding to the capacitance of the capacitor C1 constituting the parallel resonant circuit 3. In addition, it is only necessary to adjust the gap G, and it is possible to reduce the cost because it is not necessary to shorten the working time and to prepare more inductors than necessary.

DESCRIPTION OF SYMBOLS 1 Switching power supply part 2 Series resonance circuit 3 Parallel resonance circuit 4 Transformer 5 Rectification smoothing circuit 6 Current detection part 7 Control part 8 Load L1, L2 Inductor C1 Capacitor

Claims (2)

A transformer that supplies the output current of the switching power supply unit to the primary winding via a series resonant circuit and a parallel resonant circuit; and a rectifying and smoothing circuit that rectifies and smoothes the induced voltage of the secondary winding of the transformer and supplies the rectified smoothing to the load. In a switching power supply device including a current detection unit that detects a current supplied to the load from the rectifying and smoothing circuit, and a control unit that controls the switching power supply unit according to a detection signal of the current detection unit,
A switching power supply device characterized in that an inductor connected in parallel to a capacitor constituting the parallel resonant circuit has a configuration in which an inductance can be varied by adjusting a gap of a core.   The inductor includes an E-shaped core provided with a coil in a central core, an I-shaped core disposed opposite to the E-shaped core via a gap, and the I-shaped core with respect to the E-shaped core so that the gap can be adjusted. The switching power supply device according to claim 1, further comprising a configuration that supports

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