JPH08266060A - Inverter device - Google Patents

Abstract

PURPOSE: To equalize the levels of the currents flowing to individual switching elements by connecting the output end of each bridge circuit in common to load through the primary winding of each transformer corresponding to each bridge circuit, and connecting the secondary windings of these transformers in series into loop shape. CONSTITUTION: In each bridge circuit 2a-2c, the junctions between several MOS transistor 3a and 3b are connected, as the output ends of the same-phase currents, to the terminal Ra of load R through the primary windings 4a-6a of several transformers 4-6, and also the secondary windings 4b-6b of the transformers 4-6 are provided with a circular signal line 10, with the directions of their currents the same. On the other hand, the junctions of MOS transistors 3c and 3d are connected, as output ends, to the terminal Rb of the load R through the primary windings 7a-9a of the transformers 7-9 severally, and also the secondary windings 7b-9b, of the transformers 7-9 are provided with a circular signal line 11, with the directions of their currents the same. Hereby, the levels of the currents flowing to the MOS transistors 3a-3d can be equalized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter device which is a static inverse conversion device for converting a DC voltage into an AC voltage by using a switching element made of, for example, a semiconductor.

[0002]

2. Description of the Related Art Conventionally, for example, an inverter device 100 having a configuration shown in FIG. 3 is known as a static inverter device using this type of switching element. This inverter device 100 includes four N switching elements.
Channel MOSFET (Metal Oxide Semiconductor Fie
ld Effect Transistor; hereinafter referred to as MOS transistor)
Is composed of three bridge circuits 2a to 2c.

These bridge circuits 2a (2b, 2c)
Is configured by connecting in parallel a series circuit including two MOS transistors 3a, 3b and 3c, 3d connected in series between a high potential side terminal DCa and a low potential side terminal DCb of a DC power source (not shown), The connection points of the source terminal of the MOS transistor 3a and the drain terminal of the MOS transistor 3b in each of the bridge circuits 2a to 2c are commonly connected to serve as an output terminal for connecting to one end Ra of the load R, and each bridge circuit 2a. MO in ~ 2c
The connection points of the source terminal of the S-transistor 3c and the drain terminal of the MOS transistor 3d are commonly connected to serve as an output end for connecting to the other end Rb of the load R.

In the inverter device 100 having the above-mentioned structure, the bridge circuits 2a to 2c are connected from a DC power source (not shown).
When a driving signal (driving pulse) is applied to each gate terminal of the MOS transistors 3a to 3d forming the bridge circuits 2a to 2c in correspondence with a predetermined frequency in a state in which a DC voltage is supplied to each MOS, Transistor 3a
~ 3d operate in parallel in synchronization with each bridge circuit 2a ~ 2
An alternating voltage is applied to the load R from c every predetermined timing.

[0005]

However, in the inverter device 100 of the conventional example, a plurality of bridge circuits 2a to 2c are connected in parallel, and each bridge circuit 2a to 2c is connected.
Since the output terminal from c is directly connected to the load, there are the following problems.

That is, the characteristics of the MOS transistors 3a to 3d forming the bridge circuits 2a to 2c are completely the same, and the bridge circuits 2a to 2c and the load R are the same.
There is no problem when the inductance of the output line connecting to and is uniform, but in the actual circuit configuration, it is almost impossible to completely match the characteristics of the MOS transistors 3a to 3d and the inductance of the output line. Therefore, MO
The variations in the characteristics of the S transistors 3a to 3d and the non-uniformity of the inductance of the output lines cause variations in the levels of the currents flowing through the MOS transistors 3a to 3d, and the heat generated by the elements through which more current flows increases. As a result, deterioration of the element is accelerated. If this is extreme, the element will be damaged.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to provide an inverter device having a structure in which the levels of currents flowing through individual switching elements constituting a bridge circuit for DC / AC conversion are made uniform. .

[0008]

In order to solve the above problems, the present invention provides a bridge composed of a predetermined number of switching elements connected in a bridge between a high potential side power line and a low potential power line of a DC power source. A DC-AC converter is formed by connecting a plurality of circuits in parallel, and a drive signal is applied to each switching element in the DC-AC converter at each predetermined timing to change the output voltage of the DC power supply. In the inverter device that converts into an AC voltage, the DC-AC converter is configured as follows. That is,
Each of the bridge circuits has a transformer having the same number of primary and secondary windings, and the output terminal of each bridge circuit and the load are output through the primary winding of the transformer corresponding to the bridge circuit. , And the secondary windings of these transformers are connected in series by annular signal lines so that the directions of the currents flowing to the secondary windings are the same.

Each bridge circuit has two output terminals of different phases, and a secondary winding of a transformer connecting a primary winding to each of these output terminals is connected to each output terminal of the same phase, that is, a secondary winding. The windings and the secondary windings are separately connected in series by two different ring-shaped signal lines, or 1
It is configured by connecting in series with two annular signal lines. In addition,
The switching element is not limited to the N-channel MOS transistor, but may be of any other type as long as it has switching characteristics, and the bridge circuit may be replaced by, for example, a half bridge circuit. .

[0010]

When the output current flows from each bridge circuit to the primary winding of the transformer, the ring-shaped signal line on the secondary winding side connected in series is excited by the primary current flowing through the primary winding of the transformer. The secondary current flows in one direction. When the characteristics of the switching elements that configure each bridge circuit are the same and the inductance of the output signal line that connects each bridge circuit and the load is uniform, the secondary current flowing through the annular signal line is the primary winding. Since the currents flowing through the output signal lines via the lines are in a balanced state, they all have the same phase and the same level, and there is no problem as in the conventional example.

Here, because there is variation in the characteristics of the switching elements that form each bridge circuit, or the inductance of the output signal line that connects each bridge circuit and the load is uneven, the output is performed via the primary winding. It is assumed that the currents flowing in the signal lines have become unbalanced. in this case,
In the primary winding of the transformer in which a primary current of a level higher than the primary current corresponding to the secondary current flowing in the annular signal line flows, the transformer acts as an inductor due to the difference current, and suppresses the current flowing in that signal line. A voltage is generated in the direction. Similarly, a voltage is generated in the primary winding of the transformer in which a primary current having a level smaller than the primary current corresponding to the secondary current flowing in the annular signal line flows, in a direction in which the level of the current flowing in the signal line increases. . Therefore, the level of the current flowing through the output signal line through the primary winding electromagnetically coupled by the annular signal line is made uniform by compressing the difference between the signal lines.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. First Embodiment First, the configuration of the first embodiment of the present invention is shown in FIG.
Will be explained. FIG. 1 is a circuit diagram showing a main configuration of an inverter device 1 according to a first embodiment of the present invention, and the same elements as those of FIG. 3 showing a conventional example are designated by the same reference numerals. The inverter device 1 of this embodiment includes a bridge circuit 2a to 2c and a transformer 4 which form a DC-AC converter 20.
9 to 9, and the bridge circuits 2a to 2c are composed of four N-channel MOS transistors 3a to 3d, which are switching elements, respectively.

MOS in each bridge circuit 2a-2c
In-phase currents flow through the three output signal lines that are commonly connected with the connection point between the source terminal of the transistor 3a and the drain terminal of the MOS transistor 3b as an output terminal, and the primary windings 4a to 6a of the transformers 4 to 6 are passed. Load R one end R
connected to a. Further, the secondary windings 4b to 6b of the transformers 4 to 6 are provided with annular signal lines 10 so that the directions of the flowing currents are the same.

On the other hand, the above-mentioned output signal lines are the three output signal lines commonly connected with the connection point of the source terminal of the MOS transistor 3c and the drain terminal of the MOS transistor 3d in each bridge circuit 2a-2c as an output terminal. , 180 degrees out of phase with each other, and are connected to the other end Rb of the load R via the primary windings 7a to 9a of the transformers 7 to 9. In addition, the secondary windings 7b to 9b of the transformers 7 to 9
The ring-shaped signal line 11 is provided so that the flowing currents have the same direction. As a result, the phase of the current flowing through the signal line 11 is 180 times that of the current flowing through the signal line 10.
The phase will be different.

Next, an example of the operation of the inverter device 1 having the above configuration will be specifically described. A drive signal corresponding to a predetermined frequency to each gate terminal of the MOS transistors 3a to 3d forming the bridge circuits 2a to 2c in a state where a DC voltage is supplied to each of the bridge circuits 2a to 2c from a DC power source (not shown). For example, when a drive pulse is applied, each M
The OS transistors 3a to 3d operate synchronously in parallel, and an AC voltage is applied to the load R from each bridge circuit 2a to 2c at a predetermined timing.

Here, when the characteristics of the MOS transistors 3a to 3d forming the bridge circuits 2a to 2c are varied and the inductance of the output signal line connecting the bridge circuits 2a to 2c and the load R is not uniform. Since the currents flowing through the output signal lines via the primary windings 4a to 9a are in an unbalanced state, the currents flowing from the bridge circuits 2a to 2c to the MOS transistors 3a to 3d via the output signal lines vary. .

However, in this embodiment, the ring-shaped signal line 1 is used.
Primary windings 4a of transformers 4 to 9 in which a primary current larger than the primary current value corresponding to the secondary currents 0 and 11 flows
9a, a voltage is generated by the transformers 4-9 in a direction to suppress the current flowing through the signal line, and similarly, the voltage is smaller than the primary current value corresponding to the secondary current flowing through the annular signal lines 10 and 11. A voltage is generated in the primary windings 4a to 9a of the transformers 4 to 9 through which the primary current flows by the transformers 4 to 9 in a direction of increasing the current flowing through the signal line. As a result, the current flowing through the output signal line via the primary winding is made uniform by compressing the difference between the signal lines, so that only the level of the current flowing through the specific MOS transistors 3a to 3d increases. It can be avoided. As a result, it is possible to suppress abnormal heat generation of the MOS transistors 3a to 3d and the accompanying element deterioration, and it is possible to solve the problems of the conventional example.

[Second Embodiment] Next, the configuration of the second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a circuit diagram showing a main configuration of an inverter device 1 ′ according to a second embodiment of the present invention. The same components as those of the first embodiment are designated by the same reference numerals, and the description thereof will be omitted. Only different components will be described.

The inverter device 1 of the first embodiment has one
Secondary windings 4b of transformers 4 to 6 having different phases by 80 degrees
6b and the secondary windings 7b to 9b of the transformers 7 to 9 are connected in series by a ring-shaped signal line 10 and a ring-shaped signal line 11, respectively.
The nine secondary windings 4b to 9b are connected in series by one annular signal line 12. As a result, the configuration of the signal line can be simplified while having the same effect as that of the first embodiment.

As described above, in the first and second embodiments, the transformers 4 to 9 having the function of the current balancer are provided in the output signal lines of the plurality of bridge circuits (or half bridge circuits) which are conventionally connected in parallel. Since it is provided, it is possible to eliminate the variation in the current level caused by the variation in the characteristics of the switching element and suppress the deterioration and the damage of the element.

In each of the above embodiments, an example in which four N-channel MOS transistors are used as switching elements to form three bridge circuits has been described, but the present invention is not limited to these embodiments. Instead, it may be configured using semiconductor elements having similar switching characteristics, and the number thereof may be arbitrary.

[0022]

As is apparent from the above description, according to the present invention, in the inverter device using the bridge circuit composed of a plurality of switching elements, the level of the current flowing through each switching element which constitutes the bridge circuit. Has the effect of being uniformized. As a result, deterioration of the switching element is relatively suppressed, and a long-life inverter device can be realized.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a main configuration of an inverter device according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a main configuration of an inverter device according to a second embodiment of the present invention.

FIG. 3 is a circuit diagram showing a main configuration of an inverter device in a conventional example.

[Explanation of symbols]

 1, 1 ', 100 Inverter device 2a to 2c Bridge circuit 3a to 3d MOS transistor 4 to 9 Transformer 4a to 9a Primary winding 4b to 9b Secondary winding 10 to 12 Ring signal line 20 DC-AC converter

Claims (3)

[Claims] 1. A DC-AC converter comprising a plurality of bridge circuits, each of which has a predetermined number of bridge-connected switching elements, connected in parallel between a high-potential-side power line and a low-potential power line of a DC power source. An inverter device for converting the output voltage of the DC power supply into an AC voltage by applying a drive signal to each switching element in the DC-AC conversion unit at a predetermined timing. Has a plurality of transformers having the same number of primary and secondary windings corresponding to each bridge circuit, and the output terminal of each bridge circuit and the load are the primary windings of the transformers corresponding to the bridge circuit. Through the output signal line, and connect the secondary winding of the transformer so that the direction of the current flowing to the secondary winding side is the same. Inverter apparatus characterized by each formed by connecting in series by signal lines. 2. Each of the bridge circuits has two output terminals of different phases, and a secondary winding of the transformer connecting a primary winding to each of the output terminals is provided for each output terminal of the same phase. The inverter device according to claim 1, wherein the inverter devices are connected in series by two different ring-shaped signal lines. 3. Each of the bridge circuits has two output terminals of different phases, and each of the secondary windings of the transformer connecting a primary winding to each of the output terminals is formed by one annular signal line. The connection is made in series.
Inverter device described.