Patent Application
20160126829
1. Field of the Invention
The present invention relates to a power factor corrector and an inductor applied to the power factor corrector, and in particular to a power factor corrector with high-efficiency when operated between typical load and light load, and an inductor having different inductances when operated under typical load and light load.
2. Description of Related Art
In alternative current (AC) circuitry, power factor is defined by the ratio of the real power and apparent power. Power factor corrector is used for shifting wave shape and phase between the voltage and current of the received input power to reduce or minimize the phase difference between them at the output of the power factor corrector.
In the power factor corrector, inductor is used for storing energy to shift wave shape and phase between the voltage and current of the received input power. Currently, the inductor adapted in the power factor corrector includes two magnetic core and a large air gap located therebetween to prevent magnetic flux density from saturation in a short time under typical load operation. However, large air gap increases magnetic resistance when the power factor is operated under light load, thus reducing operation efficiency.
It is an object of the present invention to provide an inductor to overcome above-mentioned problem
Accordingly, the present invention provides an inductor comprising magnetic core, an auxiliary magnetic core, and a winding set. The magnetic core comprises a winding part and two opposite end surfaces. The auxiliary magnetic core comprises a top surface. The auxiliary magnetic core is attached on one of the end surfaces and spaced from the other end surface to form an air gap. The permeability of the auxiliary magnetic core is smaller than that of the magnetic core. The winding set is wound on the winding part, the air gap, and the auxiliary magnetic core. The auxiliary magnetic core achieves magnetic saturation before that of the magnetic core when a current flowing through the winding set is increased to reduce current variation per unit time of the inductor.
In an embodiment of the present invention, the magnetic core comprises a first magnetic core and a second magnetic core. The first magnetic core comprises a first central leg, two first outer legs arranged at two opposite sides of the first central leg, and two first accommodating recesses located between the first central leg and the first outer legs, the first central core comprising an end surface. The second magnetic core comprises a first central leg, two second outer legs arranged at two opposite sides of the first central leg, and two second accommodating recesses located between the first central leg and the second outer legs. The auxiliary magnetic core comprises a top surface. The first outer legs is connected to the second outer legs, the end surface of the first central core faces and is spaced from the top surface of the auxiliary magnetic core, and an air gap formed between the top surface and the end surface. The winding set is wound on the first central core, the air gap, the auxiliary magnetic core, and the second central core. The magnetic flux density of the first central core and the second central core are respectively higher than that of the auxiliary magnetic core when the current flowing through the winding set.
In an embodiment of the present invention, the magnetic core is an annular magnet.
It is an object of the present invention to provide a power factor corrector. The power factor corrector is electrically connected to an AC to DC power convertor and a load. The power factor corrector comprises the inductor 1, mentioned above, a diode D, a switch S, and a capacitor C. The inductor is electrically connected to the AC to DC power convertor, the diode is electrically connected to the inductor and the load, the switch is electrically connected to the capacitor and the diode, and the capacitor is electrically connected to the diode and the switch. The power factor corrector controls operations of the switch to control current flowing through the inductor, and shift wave shape and phase between the voltage and current of the received input power to reduce or minimize the phase difference between them at the output of the power factor corrector.
The inductor of the present invention uses the auxiliary magnetic core attached on the second central core modulates its inductances to adapt to different currents.
The features of the invention believed to be novel are set forth with particularity in the appended claims. The invention itself, however, may be best understood by reference to the following detailed description of the invention, which describes an exemplary embodiment of the invention, taken in conjunction with the accompanying drawings, in which:
A preferred embodiment of the present invention will be described with reference to the drawings.
Reference is made to
The first magnetic core 10 includes a first central leg 100, two first outer legs 102 arranged at two opposite sides of the first central leg 100, and a first base 104 connected to the first central leg 100 and the first outer legs 102. The first magnetic core 10 further includes first recesses 106 collectively defining by the first central leg 100, the first outer legs 102, and the first base 104, so that the first magnetic core 10 is substantially of E-shape. The first central leg 100, the first outer legs 102, and the first base 104 are respectively made of magnetic material, and the first central leg 100, the first outer legs 102, and the first base 104 are one-piece formed.
In this embodiment, the first central leg 100 is substantially a cylinder, so that an end surface 108 formed on the first central leg 100 and far away from the first base 104 is circular and substantially a plane.
The second magnetic core 12 includes a second central leg 120, two second outer legs 122 arranged at two opposite sides of the second central leg 120, and a second base 124 connected to the second central leg 120 and the second outer legs 122. The second magnetic core 12 further includes second recesses 126 collectively defining by the second central leg 120, the second outer legs 122, and the second base 124, so that the second magnetic core 12 is substantially of E-shaped. The second central leg 120, the second outer legs 122, and the second base 124 are respectively made of magnetic material, and the second central leg 100, the second outer legs 102, and the second base 104 are one-pieced formed. It should be note that the first magnetic core 10 and the second magnetic core 12 are made of the same material, the first magnetic core 10 and the second magnetic core 12 may be individually formed or one-piece form.
The profile of the second central leg 120 is substantially a cylinder, and an end surface 128 arranged on one side of the second magnetic core 120 and far away from the second base 120. The end surface 128 is circular and substantially a plane.
The profile of the auxiliary magnetic core 14 is cylinder and has a circular top surface 140 and a circular bottom surface 142. The top surface 140 and the bottom surface 142 are planes. The surface area of the bottom surface 142 is the same as that of the end surface 128, and the surface area of the top surface 140 is the same as that of the end surface 128. The auxiliary magnetic core 14 is, for example, made of ferrite material. The permeability of the first magnetic core 10 is larger than that of the auxiliary magnetic core 14, and the permeability of the second magnetic core 12 is larger than that of the auxiliary magnetic core 14.
The auxiliary core 14 is attached to the second central leg 142, and the bottom surface 142 of the auxiliary magnetic core 14 is attached to the end surface 128 of the second central leg 120. The inductor 1 may further include a resin 16 arranged between the second central leg 120 and the auxiliary magnetic core 14 for combining the auxiliary magnetic core 14 and the second central leg 120.
The first outer legs 102 of the first magnetic core 10 are respectively connected to the second outer legs 122 of the second magnetic core 12, the end surface 108 of the first central leg 100 faces the top surface 140 of the auxiliary magnetic core 14 and is spaced from the top surface 140 because there is an air gap 22 formed between the end surface 108 and the top surface 140. The air gap 22 is a linear air gap since the end surface 10 of the first central leg 100 and the top surface 140 of the auxiliary magnetic 14 are respectively planes.
The inductor 1 further includes a winding set 18, as shown in
The inductor 1, a diode D, a switch S, and a capacitor C may constitute a power factor corrector, as shown in
The inductor 1 is electrically connected to inputting terminal Vi and an anode of the diode D. the switch S is electrically connected to the inductor 1, the anode of diode D, and the inputting terminal Vi. The capacitor C is electrically connected to the outputting terminal Vo in parallel, and the cathode of the diode D. The switch S is, for example, a metal-oxide-semiconductor field effect-transistor (MOSFET).
The inductor 1 is charged since the switch S turns-on, and a loop is formed among the AC to DC power converter, the inductor 1, and the switch S. The inductor 1 is discharged by the diode D since the switch S turns-off, and at the mean while, the capacitor C is charged. The diode D can prevent inversing current flows through the inductor 1 when the switch S turns-off.
Besides, the inductance of the inductor 1 is the product of voltages cross the inductor and the current variation per unit time, which means L=V·(dI/dt). When the auxiliary magnetic core 14 achieves magnetic saturation, the air gap 22 of the inductance 1 is then considered increasing since the magnetic resistance of the auxiliary magnetic core 14 is increased. Thus, the current variation per unit time of the inductor 1 decreases, and then the inductance of the inductor 1 decreases.
In short, the inductor 1 of the present invention has higher inductance under light load operation and lower inductance under typical load operation, so as to shift wave shape and phase between the voltage and current of the received input power to reduce or minimize the phase difference between them at the output of the power factor corrector, and then achieves better operative efficiency.
The curve B in
In sum, the inductor 1 of the present invention uses the auxiliary magnetic core 14 attached on the second central core 120 modulates its inductances to adapt to different currents.
The permeability of the auxiliary magnetic core 13 is smaller than that of the magnetic core 11, so that the auxiliary magnetic core 13 achieves magnetic saturation earlier than that of the magnetic core 11. The auxiliary magnetic core 13 includes a top surface 130, which is substantially a plane. One of the end surfaces 112 of the auxiliary magnetic core 13 faces and is spaced from the other end surface 112, and an air gap 17 is formed therebetween. The air gap 17 is a linear air gap. The winding set 15 is wound on the winding part 110, the air gap 17, and the auxiliary magnetic core 13.
The inductor 1a, a diode, a switch, and a capacitor can collectively construct a power factor corrector shown in
Although the present invention has been described with reference to the foregoing preferred embodiment, it will be understood that the invention is not limited to the details thereof. Various equivalent variations and modifications can still occur to those skilled in this art in view of the teachings of the present invention. Thus, all such variations and equivalent modifications are also embraced within the scope of the invention as defined in the appended claims.
