JP3594944B2 - Switching circuit device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a switching circuit device suitable for use in a power conversion device such as various inverter devices.
[0002]
[Prior art]
In a conventional power conversion device, as a method of controlling the amount of AC or DC, there is a switching method of performing on / off control of a semiconductor switching element using PWM (pulse width modulation) or the like. In an inverter device that performs DC-to-AC power conversion by a switching method, a pair of switching elements are connected in series between the positive and negative poles of a DC power supply, and these elements are alternately turned on and off. Often used. In such a circuit configuration, the switching elements of both polarities may be turned on (short-circuited) at the same time, causing an excessive current to flow through the elements, thereby damaging the elements. In order to avoid this, in the conventional configuration, a dead time (a time when both are simultaneously turned off (open)) is provided. However, in the case of protecting the element by controlling the switching element such as providing a dead time, there is a problem that it is necessary to take measures against an inefficiency or a phenomenon that the element is simultaneously turned on due to noise or the like. is there.
[0003]
On the other hand, a switching circuit has been proposed in which a countermeasure against an excessive current is taken by changing a circuit configuration itself. One example of such a circuit is described in Japanese Patent Application Laid-Open No. 11-346475, "Power Supply Device" and Japanese Patent Application Laid-Open No. 2001-258270, "Power Converter". In the configurations described in these publications, a reactor is interposed between a pair of switching elements provided between power supplies, and the above-mentioned excessive short-circuit current is prevented from flowing through each element by the inductance of the reactor. I have.
[0004]
[Problems to be solved by the invention]
As described above, when an additional reactor is provided between switching elements in a switching-type power converter, an increase in cost and space is considered as a problem. Regarding the reactor, especially in the design of a magnetic circuit, it is necessary to reduce the size of the core and to secure sufficient characteristics to prevent an excessive current.
[0005]
The present invention has been made in consideration of the above-described circumstances, and aims at optimizing a design such as optimizing a magnetic circuit of a reactor provided between switching elements to easily reduce a size of a switching circuit including a reactor. It is an object of the present invention to provide a switching circuit device that can reduce the cost and cost.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 includes a first switching element in which a first switching terminal is connected to a positive terminal of a power supply, and a first winding wound around a first core . A first reactor having a first terminal connected to a second switching terminal of the first switching element, and a first terminal having a second winding wound around a second core having the first terminal connected to the first switching element. A second reactor connected to a second terminal of the first winding, a first switching terminal connected to a second terminal of the second winding, and a negative terminal of the power supply connected to a negative terminal of the power supply. includes a second switching element second switching terminal connected, and a magnetic circuit is formed to include a first core and said second core, said first, second winding A line passes through the first core generated in the first reactor when the first switching element is turned on. The first magnetic flux passing through the second core and the second magnetic flux generated in the second reactor and passing through the second core when the second switching element is turned on are relatively opposed in the magnetic circuit. And the magnetic circuit is provided with a leakage magnetic flux path that leaks and bypasses each of the first magnetic flux and the second magnetic flux when they are generated substantially simultaneously. .
[0007]
The invention according to claim 2 is characterized by further comprising a capacitor connected to a connection point between a second terminal of the first winding and a first terminal of the second winding .
[0008]
The invention according to claim 3 is characterized in that the leakage magnetic flux path includes a first magnetic gap for leaking the first magnetic flux and the second magnetic flux . According to a fourth aspect of the present invention, the magnetic circuit includes a second magnetic gap for preventing magnetic saturation of each of the first magnetic flux and the second magnetic flux. Is shorter than the gap length of the first magnetic air gap . According to a fifth aspect of the present invention, in the leakage magnetic flux path, a first path length in which the first magnetic flux generated in the first reactor returns to the first reactor and a leakage flux path generated in the second reactor are provided. A second path length where the second magnetic flux returns to the second reactor is provided at a position where the path length is substantially the same .
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram showing a circuit configuration of a switching circuit device according to an embodiment of the present invention. In the present application, a switching circuit device means a part or all of a device including a switching circuit configured using semiconductor switching elements.
[0010]
In FIG. 1, a terminal 1 is connected to a positive terminal of a DC power supply (not shown). On the other hand, the terminal 2 is connected to the negative terminal of the power supply. The terminal 3 is an output terminal, and supplies AC power to a load (not shown) connected between both terminals of the capacitor 40. The terminal 4 is connected to, for example, an intermediate potential of the DC power supply connected to the terminals 1 and 2.
[0011]
The positive terminal 1 is connected to a collector terminal of a switching element 11 composed of an IGBT (Insulated Gate Bipolar Transistor) and a cathode terminal of a diode 31. The negative terminal 2 is connected to the emitter terminal of the switching element 12 made of IGBT and the anode terminal of the diode 32. The cathode terminal of the diode 32 and one terminal of the winding A of the reactor 21 are connected to the emitter terminal of the switching element 11 (connection point {circle around (1)}). The anode terminal of the diode 31 and one terminal of the winding B of the reactor 22 are connected to the collector terminal of the switching element 12 (connection point {circle around (2)}). The other terminal of the winding A of the reactor 21 and the other terminal of the winding B of the reactor 22 are commonly connected to the output terminal 3 and one terminal of the capacitor 40 (connection point {circle around (3)}).
[0012]
A pulse signal train by PWM control is supplied to each gate terminal of the switching element 11 and the switching element 12 from a control circuit (not shown) so that each element is turned on and off alternately. In the example shown in FIG. 1, the switching elements 11 and 12 are composed of IGBTs. However, the switching elements are not limited to IGBTs, and other switching elements such as MOSFETs and bipolar transistors may be used. Further, in the configuration of FIG. 1, the capacitor 40 is directly connected to the contact point (connection point (3)) between the winding A of the reactor 21 and the winding B of the reactor 22; , A reactor or other circuit element may be interposed before connection.
[0013]
FIGS. 2 and 3 are side views showing a configuration example of the reactors 21 and 22 shown in FIG. In the example shown in FIG. 2, a set of EI-type cores is used as the cores of the reactors 21 and 22. The EI type core shown in FIG. 2 includes an I type core 201 made of a magnetic material such as iron and ferrite, and an E type core 202. In this case, the I-shaped core 201 and the E-shaped core 202 are configured to be combined so as to have a predetermined gap. The E-type core 202 includes a core 202a and a core 202b that form the legs on both sides of the E-type, a core 202c that forms the center leg (intermediate leg), and a yoke that connects the cores 202a to 202c. 202d. Here, since the core 202c is configured to be shorter than the other cores 202a and 202b, the gap length between the cores 201a, 202b, and 202c and the core 201 is equal to the core length. The distance between the core 202c and the core 201 is the largest.
[0014]
2, the winding A of the reactor 21 is wound around the core 202a, and the winding B of the reactor 22 is wound around the core 202b. The winding A and the winding B are wound in the same phase on one magnetic circuit formed of the core 202a, the core 201, the core 202b, and the core 202d in order. Therefore, even when the terminals at the beginning of winding of the winding A and the winding B (connection points (1) and (2); terminals indicated by black circles in the drawing) are connected to each other (short-circuited), A and the winding B operate as one winding of one reactor.
[0015]
On the other hand, in the example illustrated in FIG. 3, the cores of the reactors 21 and 22 in FIG. 1 are configured by two cut cores 203 and 204, respectively. The cut core 203 is composed of a pair of cores 203a and 203b, and the cut core 204 is composed of a pair of cores 204a and 204b. The core 203a and the core 204a are joined together at a plane C such that their side surfaces are in contact, and the core 203b and the core 204b are joined together at a plane D such that their respective side surfaces are in contact. The core 203a and the core 204a are combined so as to face the core 203b and the core 204b with a predetermined gap.
[0016]
In the configuration of FIG. 3, the winding A of the reactor 21 is wound around a position different from the surfaces C and D of the core 203 (the leg opposite to the leg forming the surface C or D in the illustrated example). Similarly, the winding B of 22 is wound at a position different from the planes C and D of the core 204. The winding A and the winding B are wound in the same phase on one magnetic circuit formed of the core 203a, the core 204a, the core 204b, and the core 203b in order. Therefore, even when the terminals at the beginning of winding of the winding A and the winding B (connection points (1) and (2); terminals indicated by black circles in the figure) are connected (short-circuited) to each other, one terminal is also connected. It operates as a winding.
[0017]
Next, the operation of the embodiment described with reference to FIGS.
[0018]
As shown in FIGS. 2 and 3, the windings A and B constituting the reactors 21 and 22 are wound in the same phase on one magnetic circuit. Will be the same. In this case, for example, when a positive electrode is applied to the connection point {circle around (1)} and a negative electrode is applied to the connection point {circle around (2)} (that is, when the switching elements 11 and 12 are simultaneously turned on = short-circuit state), the windings A and B are generated. The magnetic fluxes Φ ₁₃ and Φ ₃₂ of each other are brought into abutting form (a state in which the magnetic fluxes cancel each other), and an excessive current tends to flow through both windings.
[0019]
In the above state, unlike the present embodiment, if there is no magnetic detour, the magnetic flux cannot increase (change), so that no voltage can be induced in the winding and an excessive current flows. However, if the structure of this embodiment, since the intermediate magnetic gap to make the detour (magnetic leak structure), passes through the detour magnetic flux generated from each of the winding as the magnetic flux [Phi _13a and [Phi _32a, By increasing (changing), a voltage can be applied (induced) to the winding A and the winding B.
[0020]
That is, even when a reverse-phase voltage is applied to the winding A and the winding B (even when the switching terminals of the switching element 11 and the switching element 12 are simultaneously turned on), the magnetic detour (magnetic leakage) operation is performed. Excessive current can be prevented from flowing.
[0021]
On the other hand, for normal operation (when the switching element 11 and switching element 12 is in a state such that alternately turned on), the magnetic flux generated from the coil A is the winding A as magnetic flux [Phi ₄ cores (core 202a or and those flowing from the core 203) via the core (core 202b or core 204) of the winding B, and is intended to bypass the intermediate magnetic gap as flux [Phi _13a, when viewed from the winding a Since there is one magnetic circuit, the operation as the self-inductance is the same as the structure when the winding B is omitted (the structure when the reactor 21 and the reactor 22 are replaced with one reactor).
[0022]
Similarly, since the direction of the magnetic flux passing through the core (core 202b or core 204) of the winding B is also a single magnetic circuit, the voltage polarity induced in the winding B is the same as that of the winding A (in-phase), and the switching is performed. The voltage transitions of the element 11 and the switching element 12 are also the same (in-phase) with the structure in which the winding B is omitted (the structure in which the reactor 21 and the reactor 22 are replaced with one reactor).
[0023]
Further, magnetic flux energy is accumulated in one magnetic circuit (loop) in the core (core 202a or core 203) of the winding A, and energy due to self-inductance when the switching element 11 is turned off is released to the winding A. can do.
[0024]
However, the core of winding B (core 202b or core 204) has two magnetic gaps (two gaps between core 201 and cores 202b and 202c or two gaps between cores 204a and 204b). ), The magnetic flux in the same direction passes therethrough, so that no magnetic flux energy is accumulated. However, since the magnetic circuit through which the magnetic flux from the winding B passes is also a part of the magnetic circuit including the winding A, it is stored as magnetic energy for the core (core 202a or core 203) of the winding A.
[0025]
The constitutional features of the present invention are summarized as follows. {Circle around (1)} One magnetic circuit is provided with two windings, and the common connection point of the switching elements is separated so that short-circuit current does not flow. {Circle around (2)} Two windings allow two switching elements to generate magnetic flux in the same direction for the same voltage polarity. {Circle around (3)} The respective ends of the two windings are connected in common and connected to the system power supply side, but are wound separately from each other. (4) The magnetic flux energy generated from the two windings is generated by the same magnetic core. (5) An escape path for the magnetic flux when the switching elements connected to the two windings are turned on at the same time is provided almost in the middle from the two windings to prevent an excessive current. {Circle around (6)} In the case of the EI type core, the intermediate magnetic pole is shortened, and this is used as a magnetic detour. {Circle around (7)} In the case of a cut core, two magnetic circuits are brought into close contact with each other to form a magnetic detour. {Circle around (8)} Diodes for energy recovery due to self-inductance are connected to power sources on the other side.
[0026]
That is, in the present invention, (1) two switching elements forming a pair such as a PWM inverter are separately connected to two windings of a reactor (choke transformer), and (2) a conventional reactor (choke transformer) is used. Compared to the structure in which the single winding is used, the reactor has two windings, the winding positions are separated, and when voltages of opposite polarities are applied to the respective windings, the magnetic flux detours (does not saturate). (3) When the in-phase voltage is applied to the two windings (normal operation), the winding is located at a position where the middle magnetic gap (detour) does not affect (even when the winding is detoured). The main feature is that it is located. That is, in the present invention, one of the main features of the present invention is that when in-phase voltages are applied to the two windings, the magnetic fluxes are in the same direction, and when the polarities are opposite, the magnetic fluxes can be bypassed. It is a feature.
[0027]
According to the present invention, the following effects can be obtained by the above structural features. (1) Even if two switching elements are turned on at the same time, short-circuit current does not flow, so complicated and high-precision control such as dead time is not required, so that the device is simple and highly reliable (hard to break). , Will be cheaper. (2) The effect of (1) can be obtained with the same one component material as the conventional magnetic core using only one reactor. (3) Regardless of the shape of the magnetic core, either the EI type or the cut core type, parts can be reused without changing the core shape from the conventional method using only one reactor, so the development period is short if there is a conventional device Can be between. (4) Since the dead time in the switching operation can be minimized, the inverter efficiency is increased. (5) Since the rising gradient of the voltage applied to the other switching element when one of the switching elements is turned on is reduced, the load and loss of the switching element are almost eliminated, and the rated capacity of the switching element can be margined. (6) It can be applied to synchronous rectification type switching power supplies other than AC inverters.
[0028]
【The invention's effect】
According to the present invention, the first reactor and the second reactor provided between the switching elements are replaced by the first core constituting the first reactor and the second core constituting the second reactor. A first magnetic circuit is formed, a first winding and a second winding are wound in the same phase on the first magnetic circuit, and a current flowing from a positive terminal to a negative terminal of a power supply is formed. When the magnetic flux generated in each winding when flowing through the series circuit consisting of the first winding and the second winding forms a second magnetic circuit through which the magnetic flux passes in the same direction, the core shape of the reactor is changed. Since the design can be performed more efficiently and the short circuit current flowing through the switching element can be easily prevented, the size and cost of the switching circuit including the reactor can be reduced.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing an electric circuit configuration according to one embodiment of the present invention.
FIG. 2 is a side view showing a configuration example of reactors 21 and 22 in FIG.
FIG. 3 is a side view showing another configuration example of the reactors 21 and 22 of FIG. 1;
[Explanation of symbols]
11, 12: switching elements 21, 22: reactors 31, 32: diodes

Claims (5)

A first switching element having a first switching terminal connected to a positive terminal of the power supply;
A first reactor having a first terminal of a first winding wound on a first core connected to a second switching terminal of the first switching element;
A second reactor having a first terminal of a second winding wound on a second core connected to a second terminal of the first winding;
A second switching element having a first switching terminal connected to a second terminal of the second winding and a second switching terminal connected to a negative terminal of the power supply;
A magnetic circuit formed to include the first core and the second core;
With
The first and second windings include a first magnetic flux, which is generated in the first reactor and passes through the first core when the first switching element is turned on, and a second switching element. A second magnetic flux generated in the second reactor and passing through the second core when the element is turned on is wound so as to face the inside of the magnetic circuit,
The switching circuit device, wherein the magnetic circuit is provided with a leakage magnetic flux path that leaks and bypasses the first magnetic flux and the second magnetic flux when they are generated substantially simultaneously . The switching circuit device according to claim 1, further comprising a capacitor connected to a connection point between a second terminal of the first winding and a first terminal of the second winding . 3. The switching circuit device according to claim 1 , wherein the leakage magnetic flux path includes a first magnetic gap that leaks the first magnetic flux and the second magnetic flux . 4. The magnetic circuit includes a second magnetic gap for preventing magnetic saturation of each of the first magnetic flux and the second magnetic flux,
4. The switching circuit device according to claim 3 , wherein the gap length of the second magnetic gap is shorter than the gap length of the first magnetic gap . The leakage flux path includes a first path length in which the first magnetic flux generated in the first reactor returns to the first reactor, and a second path generated in the second reactor. The switching circuit device according to any one of claims 1 to 4, wherein the second path length returning to the second reactor and the second path length are provided at positions where the path lengths are substantially the same .

Images