JP2690898B2 - Power factor improvement circuit - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a power factor correction circuit, and more particularly to a power factor correction circuit suitable for improving efficiency without using an AC current detection resistor. . [Prior Art] A conventional power factor correction circuit will be described with reference to FIGS. 3 and 4. FIG. 3 is a circuit diagram of a conventional power factor correction circuit, and FIG.
It is a signal and AC current waveform diagram explaining operation | movement of a power factor correction circuit. In FIG. 3, 1 is a DC control unit, 2 is an AC control unit,
3 is a photocoupler, 4 (a generic name of 4-a, 4-b, 4-c, 4-d) is a diode for reverse blocking, and 5 (a generic name of 5-a, 5-b) is a smoothing capacitor ( Hereinafter, simply referred to as capacitors), 6 (collective names of 6-a, 6-b) are transistors related to switching elements, 7 is a DC current detection resistor, 8 is a reactor, 11 is an AC current detection resistor, 9 is a commercial power supply, 10 Is a load, which constitutes a power factor correction circuit for a rectifying and smoothing circuit. The DC control unit 1 changes the duty according to the magnitude of the DC current detected by the DC current detection resistor 7,
The chopper signal shown in FIG. 4 (a) is generated. The on-duty of this chopper signal changes in proportion to the magnitude of the direct current. Then, the chopper signal is transmitted via the photocoupler 3 to the AC control unit 2 having a different potential. On the other hand, when the AC current detected by the AC current detection resistor 11 exceeds a preset limit value, the AC control unit 2 outputs a current suppress signal (hereinafter simply referred to as suppress signal) shown in FIG. 4 (b). Occur. Then, the suppress signal and the chopper signal are combined to generate the drive signal shown in FIG. 4 (c) to drive the transistors 6-a and 6-b. By performing such control, the alternating current has a waveform as shown in FIG. 4 (d), and the power factor is improved. Next, the principle will be described. When the transistors 6-a and 6-b are not switched at all, the instantaneous voltage of the commercial power source 9 is the capacitor 5-
The current flows only when the terminal voltages of a and 5-b are exceeded, and the power factor is low. Therefore, when the instantaneous voltage of the commercial power supply 9 is lower than the terminal voltage of the capacitors 5-a and 5-b, the transistors 6-a and 6-b are switched, and a short-circuit current flows in the reactor 8 when in the on state. This causes this current to flow through the diodes 4-a and 4-b when in the off state. That is, even when the instantaneous voltage of the commercial power source 9 is lower than the terminal voltage of the capacitors 5-a and 5-b, the current can flow, and the AC current waveform has the fourth waveform.
As shown in the figure, the power factor is improved. [Problems to be Solved by the Invention] In the above-mentioned conventional technique, an alternating current detection resistor is used to generate a suppress signal, which increases loss,
That is, there is a problem that the efficiency is lowered. The present invention has been made in order to solve the above-mentioned problems of the prior art, and provides a highly efficient improvement circuit that can generate a suppress signal without using an AC current detection resistor and has no loss due to the AC current detection resistor. Is the purpose. [Means for Solving Problems] In order to achieve the above object, the power factor correction circuit according to the present invention has a configuration in which a commercial power source is received, a rectifying and smoothing circuit including a rectifier and a smoothing capacitor is provided, and an inductance and a switching are provided. In a switching type power factor correction circuit provided with an element and a reverse blocking diode, a gap is provided in the core of the reactor relating to the inductance, and a Hall element is inserted in this gap to detect the current of the commercial power supply, and the switching element The control signal is generated. In particular, the core of the reactor is made of an amorphous magnetic material. It should be noted that the above object is achieved by inserting a Hall element into the gap of the reactor, detecting the current of the commercial power supply, and generating a suppress signal. [Operation] The current from the commercial power supply to the rectifying and smoothing circuit is detected by the Hall element inserted in the gap of the reactor. The suppress signal can be generated by comparing the detected current waveform signal with a preset voltage in the AC control unit. [Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is a circuit diagram of a power factor correction circuit according to an embodiment of the present invention, and FIG. 2 is a perspective view showing a reactor and a Hall element used in the circuit of FIG. In the drawing of FIG. 1, the same reference numerals as those in the previous FIG. 3 are the same parts as in the prior art, and therefore the description thereof will be omitted. In FIGS. 1 and 2, reference numeral 12 is a reactor provided in series with the commercial power source 9, and the core 12-a of the reactor 12 is formed of an amorphous magnetic material. Here, the amorphous magnetic material is an amorphous material in which constituent atoms are irregularly arranged, and as a material, for example, B (boron), P (phosphorus) is used in order to easily form an amorphous alloy. ), Si (silicon) and other semi-metals are added to the magnetic alloys such as Fe (iron), Ni (nickel) and Co (cobalt). Since the amorphous magnetic substance has an irregular atomic arrangement, the crystal magnetic anisotropy constant is reduced, and it is expected that the amorphous magnetic substance exhibits high magnetic permeability. The reactor 12 is formed of an amorphous magnetic material as described above, and has a core 12-a to improve the saturation magnetic flux density.
A gap 12-b is provided in the above, and a Hall element 13 is further inserted so that the current can be measured. Hall elements include Ge for elemental semiconductors and InAs, InS for compound semiconductors.
b etc. are used. The rectifying / smoothing circuit shown in FIG. 1 has diodes 4-a and 4-b and capacitors 5-a and 5-b, and constitutes a voltage doubler rectifying circuit for receiving a commercial power supply 9. A transistor 6-a in which the reactor 12 is provided in series with the commercial power source 9 and the commercial power source 9 is short-circuited through the reactor 12.
And 6-b. The reactor 12 is made of an amorphous magnetic material. A core 12-a is provided with a gap 12-b, and a Hall element 13 is inserted in the gap 12-b so as to be proportional to the current flowing through the reactor 12. To detect the changing magnetic field.
The Hall element 13 outputs a current proportional to the change in the magnetic field to the AC control unit 2. The AC control unit 2 generates a suppress signal when the AC current detected by the hall element 13 exceeds a preset control value. The suppress signal and the chopper signal are combined to generate a drain signal, and the transistors 6-a and 6-
Drive b. The principle that the power factor is improved by switching the transistors 6-a and 6-b is the same as that described in the related art, and thus the description thereof is omitted. According to the present embodiment, the AC current detection resistor that has been conventionally used is no longer necessary, so the loss due to this AC current detection resistor is eliminated (10 W loss is reduced in this embodiment), the efficiency is improved, and the heat generation is reduced. It is possible to bring about effects such as reduction, omission of a radiator for radiating the heat generated by the resistor, miniaturization of the device due to omission of the radiator, and improvement of reliability. [Effects of the Invention] As described above, according to the present invention, a suppressed signal can be generated without using an AC current detection resistor, and there is provided a power factor correction circuit that is efficient and has no loss due to an AC current detection resistor. be able to.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram of a power factor correction circuit according to an embodiment of the present invention, FIG. 2 is a perspective view showing a reactor and a Hall element used in the circuit of FIG. FIG. 3 is a circuit diagram of a conventional power factor correction circuit, and FIG. 4 is a signal and AC current waveform diagram for explaining the operation of the power factor correction circuit. 1 ... DC control unit, 2 ... AC control unit, 4-a, 4-b, 4--
c, 4-d ... Diode, 5-a, 5-b ... Capacitor,
6-a, 6-b ... Transistor, 9 ... Commercial power supply, 12 ...
… Reactor, 12-a… Core, 12-b… Gap, 13… Hall element.

Claims (1)

(57) [Claims] A reactor that is provided on the AC side of a rectifying and smoothing circuit having a rectifier and a smoothing capacitor and that is connected in series with a power supply,
A first switching element connected in parallel to the power supply and the reactor, a first series connection body of the first reverse blocking diode, a second switching element connected in parallel with the first series connection body, and a first series connection body. A reverse blocking diode and a second series-connected body of a second reverse element diode of opposite polarity and a second series connection body, and a Hall element inserted in a gap provided in the core of the reactor. And a control means for controlling the first and second switching elements based on the alternating current signal from the hall element.