JPH04295272A - Magnetic amplifier switching regulator - Google Patents

Abstract

PURPOSE:To get a wide control range by decreasing the dead angle, and suppress the occurrence of unnecessary power loss. CONSTITUTION:By the secondary winding W2 of a saturatable reactor SR and the diode provided at this secondary winding W2, the energy of an failure reset current is released and the dead angle is made small, whereby it is made not to cause unnecessary power loss and the control range is widened.

Description

[Detailed description of the invention]

[Object of the invention]

0002

[Industrial Application Field] The present invention relates to a mag-amp switching regulator that uses a saturable reactor to control the output voltage.In particular, the unnecessary voltage drop caused by the saturable reactor, that is, the dead angle, is reduced, and the output can be controlled. Concerning mag-amp switching regulators with expanded range.

0003

2. Description of the Related Art Switching regulators are widely used as power sources for various electronic devices because of their small size, light weight, and high efficiency.

In particular, mag-amp type switching regulators that use saturable reactors for output control have been increasing due to the need for multiple outputs and high reliability of power supplies.
The saturable reactor uses an amorphous core that can handle higher switching frequencies.

FIG. 9 is a circuit diagram of a forward switching regulator using voltage control using a conventional mag-amp.

In this mag-amp type switching regulator, by periodically turning on and off the switching element Q on the primary side of the main transformer T, the input DC current is converted to a high frequency, and the input DC current is transferred to the output side via the main transformer T. This is then rectified and smoothed and supplied to the load. On the other hand, the control circuit 1 compares the output voltage with a predetermined reference voltage value, and causes a reset current to flow through the saturable reactor SR via the diode 2 based on the comparison result. By doing this, the saturable reactor SR is used as a switch for alternating current to control the output voltage.

By the way, the squareness ratio of the saturable reactor SR is ideally 1, but in reality it is not 1, and for this reason, control can be achieved simply by inserting the saturable reactor SR on the secondary side of the main transformer T. Even if the circuit 1 is not reset, an unnecessary voltage drop will occur. That is, a pulse is applied to the saturable reactor SR, and when the pulse is turned off, the magnetic flux changes from Bm to Br on the magnetization curve as shown in FIG. Further, the magnetic flux changes to a lower value (in some cases, to a negative magnetic flux) due to the reverse recovery current of the diode D1. When the next pulse rises in this state, the pulse voltage is reduced until the magnetic flux is saturated. This is a dead angle (uncontrollable angle).
For this reason, the saturable reactor SR causes an unnecessary voltage drop even if no control is applied.

[0008]

SUMMARY OF THE INVENTION As described above, in conventional mag-amp switching regulators, unnecessary voltage drops occur due to dead angles.

[0009] The present invention was devised to solve these problems, and an object of the present invention is to provide a mag-amp type switching regulator that reduces dead angles and prevents unnecessary power loss. .

[Configuration of the invention]

[0011]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the mag-amp type switching regulator of the present invention includes a switching element that converts direct current into a pulsed signal, and a pulsed signal generated by this switching element from the primary side. A transformer for supplying power to the secondary side, a primary side connected to the secondary side of said transformer, and a diode connected to the secondary side to emit a fault reset current, the inductance of which can vary depending on the magnetization state. A saturable reactor and a rectifier that rectifies and smoothes the signal after passing through the saturable reactor.
It is characterized by comprising a smoothing circuit and a control circuit that causes a reset current to flow through the saturable reactor so as to change the magnetization state of the saturable reactor based on the DC voltage output from the rectification/smoothing circuit.

0012

In the mag-amp switching regulator of the present invention, the energy of the fault reset current is released by the secondary winding of the saturable reactor and the diode provided in the secondary winding.

[0013] Therefore, the dead angle is reduced,
No unnecessary power loss occurs and the control range becomes wider.

[0014]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram showing the configuration of a mag-amp forward switching regulator which is an embodiment of the present invention.

The switching regulator shown in the figure includes a bridge circuit 3 consisting of four diodes that performs full-wave rectification from input alternating current and converts it into direct current, a switching circuit 4 that switches the direct current converted by bridge circuit 3, A transformer T transforms the signal that has been switched by the switching circuit 4 and has a pulsed waveform, and a transformer T that acts as a reactance for the pulsed signal transformed by the transformer T to perform switching of the pulsed signal. A saturable reactor SR, diodes D1 and D2 that rectify and smooth the pulsed signal controlled by the saturable reactor SR, a choke coil L, a capacitor C, and an output DC voltage and a reference voltage (not shown). and a control circuit 6 that makes a comparison and flows a reset current to the saturable reactor SR via a backflow prevention diode 5 according to the comparison result. The saturable reactor SR has a primary winding W1 and a secondary winding W2, the primary winding W1 is connected in series to the secondary winding of the transformer T, and the secondary winding W2 A diode is connected in parallel with.

Next, the operation of the switching regulator configured as described above will be explained.

First, the input alternating current is subjected to full-wave rectification in the bridge circuit 3 made up of four diodes. Thereafter, a control signal from the controller 8 applies a pulse of a predetermined frequency to the gate of the transistor Q of the switching circuit 4 to perform a switching operation. This switched pulsed signal is transformed by a transformer T and outputs a pulsed signal of a predetermined voltage to the secondary side.

After controlling the saturable reactor SR, which will be described later, half-wave rectification is performed by the diode D1.
Smoothing is performed by the diode D2, choke coil L, and capacitor C, and the voltage is output as a DC voltage.

On the other hand, the control circuit 6 detects the output voltage V, compares this output voltage V with a reference voltage that the control circuit 6 has internally, and directs a current to the diode 5 according to the voltage difference. A reset current is passed through the saturable reactor SR through the reset current, and the saturable reactor SR is magnetized while the transistor Q is off. When the transistor Q is turned on, the saturable reactor SR acts to block the output signal of the transformer T, and after a predetermined time has elapsed, a pulse-like signal output from the secondary side of the transformer T is used to block the saturable reactor SR. S
R is magnetized to the saturation region, the inductance of the saturable reactor SR decreases, and the saturable reactor SR is turned on to pass the pulsed signal to the rectifying and smoothing circuit. In this way, the amount of reset current flowing while the transistor Q of the switching circuit 4 is off is controlled to control the degree of magnetization of the saturable reactor SR, thereby blocking the pulsed voltage output from the transformer T for a certain period of time. The output voltage is controlled by Note that Figures 2 (a) and (b) are diagrams showing the voltage and current appearing on the secondary side of the transformer of a conventional mag-amp switching regulator, and Figure 3 shows the hysteresis loop of the magnetic field when a current of 3A flows. FIG. FIGS. 4(a) and 4(b) are diagrams showing the voltage and current appearing on the secondary side of the transformer of the mag-amp switching regulator of this embodiment, and FIG. FIG. 3 is a diagram showing a hysteresis loop of a magnetic field.

By the way, most of the dead angle is caused by the core of the saturable reactor SR being reset by the reverse recovery current of the diode D1. Therefore, this unnecessary reset amount called a fault reset is released as energy through the diode 7 provided in parallel with the secondary winding W2 of the saturable reactor SR, which is a feature of this embodiment, thereby generating the next on-pulse. The dead angle when it comes will be reduced.

[0022] The windings applied to the saturable reactor SR may include windings other than the above-mentioned secondary winding W2. In addition, from the viewpoint of low iron loss, the saturable reactor SR of this embodiment is made of a Co-based amorphous alloy or an Fe-based ultrafine crystal alloy (for example, Fe74Cu1Nb3S
i13B9) is preferred, and a saturable reactor using a Co-based amorphous alloy with a plate thickness of 3 to 25 μm is particularly preferred.

Next, the results of an experiment using the switching regulator configured as described above will be explained.

First Experimental Example The pulse applied to the gate of the transistor Q of the switching circuit 4 was 150 kHz, the output was 12 V, the rated current was 3 A, and the saturable reactor SR had an outer diameter of 18 mm and an inner diameter of 12 m.
m, height 4.5 mm, 30 turns of primary winding and 1 turn of secondary winding W2 were wound, and a diode of model number 10DL2CZ41A was connected to this secondary winding W2. The regulation characteristic of the output voltage in this case is expressed by the secondary winding W
A comparison was made between cases with and without 2. As shown in FIG. 6, in this experimental example, even when a load current of 4 A is applied, the constant voltage property is not lost, and an output of 12 V is obtained. On the other hand, the conventional 2
If there is no secondary winding W2, the voltage will drop from 12 V at a load current of 1.5 A or more, and the constant voltage property will be lost. That is, the saturable reactor S according to this embodiment
The control range is widened by the secondary winding W2 of R and the diode 7.

Second Experimental Example The pulse applied to the gate of the transistor Q of the switching circuit 4 was 200 kHz, the output was 10 V, and the rated current was 4 A. The saturable reactor SR had a saturable core (outer diameter 15 mm , inner diameter 10 mm, height 5.0 mm), the primary winding W1 has 30 turns, the secondary winding W2 has 1 turn, and this secondary winding W2 has model number 1.
A diode of 0DL2CZ41A was connected. In this case, a constant voltage could be obtained up to a load current 2.5 times higher than in the case where there is no secondary winding of the saturable reactor SR.

Further, as shown in FIG. 7, secondary windings W21 and W22 are provided on the secondary side of the saturable reactor SR. A current corresponding to the output voltage from the control circuit 6 flows into the secondary winding W21, and a diode 7 is connected to the secondary winding W22. In this way, by causing a reset current to flow through the secondary winding W21 of the saturable reactor SR via the diode 5, a magnetic field is generated in the primary winding W1, and a fault reset component is transmitted from the secondary winding W22 to the diode 7. is released as energy through FIG. 8 is a diagram showing the relationship between current and voltage when a switching regulator having such a configuration is operated at a frequency of 145 kHz and an output voltage of 12 V. Also, in this case,
The primary winding W1 of the saturable reactor SR has 30 turns, 2
The secondary winding W21 had 30 turns, and the secondary winding W22 had 1 turn. As shown in the figure, compared to conventional switching regulators whose constant voltage performance is impaired at 1.5 A,
In this example, a constant voltage of up to 4A was obtained.

[0027]

[Effects of the Invention] According to the mag-amp switching regulator of the present invention, the energy of the fault reset current is released by the secondary winding of the saturable reactor and the diode provided in the secondary winding, so the dead angle can be reduced. This reduces unnecessary power loss, and the control range becomes wider.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing the configuration of a mag-amp switching regulator that is an embodiment of the present invention.

FIG. 2 is a diagram showing the voltage and current of a mag lamp section of a conventional mag amp switching regulator.

FIG. 3 is a diagram showing an actual magnetic hysteresis loop of a saturable reactor of a conventional mag-amp switching regulator.

FIG. 4 is a diagram showing the voltage and current of the mag lamp section of the mag amplifier type switching regulator shown in FIG. 1;

FIG. 5 is a diagram showing an actual magnetic hysteresis loop of the saturable reactor of the mag-amp switching regulator of this embodiment.

6 is a graph showing the relationship between the output voltage and output current of the mag-amp switching regulator shown in FIG. 1. FIG.

FIG. 7 is a circuit diagram showing the configuration of a mag-amp switching regulator according to another embodiment of the present invention.

8 is a graph showing the relationship between the output voltage and output current of the mag-amp switching regulator shown in FIG. 7. FIG.

FIG. 9 is a circuit diagram showing the configuration of a conventional mag-amp switching regulator.

10 is a diagram showing a magnetic hysteresis loop of the saturable reactor of the mag-amp switching regulator shown in FIG. 9. FIG.

[Explanation of symbols]

3...Bridge circuit 4...Switching circuit 5, D1, D2, 7...Diode 6......Control circuit 8... Controller Q...Transistor SR...Saturable reactor L……Choke coil C……Capacitor T……Trance

Claims (1)

[Claims] 1. A switching element that converts direct current into a pulsed signal, a transformer that supplies power from a primary side to a secondary side of the pulsed signal generated by the switching element, the primary side being connected to the secondary side of the transformer. , a diode is connected to the secondary side to emit a fault reset current, a saturable reactor whose inductance changes depending on the magnetization state, and a rectification/smoothing circuit that rectifies and smoothes the signal after passing through the saturable reactor. , a control circuit that flows a reset current to the saturable reactor so as to change the magnetization state of the saturable reactor based on the DC voltage output from the rectifying/smoothing circuit.