JPH0467436B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to an inverter circuit that converts DC voltage to AC voltage, and particularly relates to a configuration that prevents surge voltage in the circuit and simplifies wiring. .

[Conventional technology]

2. Description of the Related Art Generally, in an electric circuit using electronic components such as semiconductor switching elements, a surge voltage is generated in the circuit due to switching operations by the switching elements. FIG. 1 is a switching circuit diagram using a general transistor. In the figure, 1 is a transistor, 2 is an inductance, and 3 is a resistor. When transistor 1 is turned on to conduct current and transistor 1 is turned off to cut off the current, a surge voltage is generated in the circuit. Figure 2a is a graph of the current waveform, and Figure 2b is a graph of the voltage waveform.The generation of the surge voltage according to Figure 1 above is caused by the generation of surge voltage due to Ldi/dt, as shown in Figure 2b. This often makes switching operations of semiconductor switches such as transistor 1 difficult. In addition, it sometimes became a factor that destroyed semiconductor switches. Therefore, in order to prevent this, a method is used to reduce the surge voltage by reducing the inductance 2 in the circuit. As an example of an inverter circuit, a conductor is used in which an AC output line is sandwiched between a positive side input line and a negative side input line of a DC input line via an insulator.

FIG. 5 is a circuit diagram of a three-phase inverter having a conventional semiconductor switching element.
It includes a positive side P line 4 and a negative side N line 5 of the DC side power supply line, and a DC filter capacitor C6. The U-phase inverter stack 7, the V-phase inverter stack 8, and the W-phase inverter stack 9 are connected to the DC power supply line by laminate bars 10, 11, and 12, respectively. The laminate bars 10, 11, and 12 are each connected to a U-phase AC output line U.
13. A V-phase AC output line V14 and a W-phase AC output line W15 are sandwiched and laminated by a positive P line 4 and a negative N line 5, respectively. A U-phase AC output line U13, a V-phase AC output line V14, and a W-phase AC output line W15, which are AC output lines of each phase, are each drawn out to the DC side. The U-phase inverter stack 7 includes a transistor _TR11 .
6. Transistor TR ₂ 17, V-phase inverter stack 8 is connected to transistor TR ₃ 18, transistor TR ₄ 19, W-phase inverter stack 9 is connected to transistor TR ₅ 20, transistor TR ₆ 21, respectively. .

A conventional inverter circuit is configured as described above. For example, regarding the U-phase inverter stack 7 and the laminate bar 10, the positive side P line 4 and the negative side N line 5 pass through the laminate 10 to the U-phase inverter stack 7 and the laminate bar 10. Supply electricity to the transistor TR ₁ 1
6. The transistor TR ₂ 17 is alternately turned on and off to generate a voltage and cause current to flow in the U-phase AC output line U13. First, when the transistor TR ₁ 16 is on and the transistor TR ₂ 17 is off, the positive side P
The current in the line 4 passes through the transistor TR ₁ 16 and goes out to the U-phase AC output line U13, so in the laminate bar 10, the current in the positive P line 4 and the current in the U-phase AC output line U13 are opposite. They become oriented and cancel out the magnetic flux generated by each other. Also, the transistor TR ₁ 1
6 is off and the transistor TR ₂ 17 is on, the current of the U-phase AC output line U 13 passes through the transistor TR ₂ 17 and returns to the negative side N line 5. The current in the AC output line U13 and the current in the negative side N line 5 are in opposite directions and cancel out the generated magnetic fluxes. In this way, the laminate bar 10 becomes a wiring with low inductance. Note that the same operation is performed for each phase of the V-phase AC output line V14 and the W-phase AC output line W15, so that the laminate bars 11 and 12 are wired with low inductance.

[Problem to be solved by the invention]

In the conventional inverter circuit as described above, the U-phase AC output line U13, the V-phase AC output line V14,
Since each output line of each phase of the W-phase AC output line 15 is sandwiched between the positive side P line 4 and the negative side N line 5 and is laminated, there are three layers for each phase, three laminated bars for the third phase, and the conductor. In addition, six positive P lines 4 and six negative N lines 5 are output from the DC filter capacitor C6, and U-phase AC output lines U13 and V
Phase AC output line V14, W phase AC output line W15
Since the current is close to the DC side, the wiring becomes complicated and the circuit itself becomes complicated.

This invention was made to solve this problem, and is a circuit with small inductance.
Furthermore, the object is to obtain a simple inverter circuit without complicated wiring.

[Means to solve the problem]

The inverter circuit according to the first invention has a pair of switching elements connected in series, and has a plurality of inverter circuits having positive and negative DC input terminals at both ends of the pair of switching elements and AC output terminals at the connection point. A switching element stack is provided, and the plurality of switching element stacks are connected in series to the positive DC input terminal by a positive DC input line, the negative DC input terminal to the negative DC input line, and the plurality of switching element stacks are connected in series to the above-mentioned positive DC input terminal by a negative DC input line, and to the AC output terminal. are connected to each other by an AC output line, the DC input line and the AC output line connected to the respective terminals are drawn out in opposite directions, and the AC output line and the positive and negative DC input lines are They are insulated through an insulator and integrated in parallel so that the inductance caused by the flowing current mutually cancels out each other.

Moreover, the inverter circuit according to the second invention is
In the inverter circuit according to the first invention, AC output lines and positive and negative DC input lines that cross between a plurality of switching element stacks are laminated with an insulator interposed therebetween, forming an integrally formed bar-shaped laminated structure. It is something.

Further, the inverter circuit according to the third invention is
The inverter circuit according to the first invention has a twisted structure in which the AC output lines and the positive and negative DC input lines that cross between the plurality of switching element stacks are insulated and twisted together.

[Effect]

In the first to third inventions, the AC output line and the positive and negative DC input lines that cross between the plurality of switching element stacks are integrated in parallel via an insulator,
The inductance generated by the positive and negative DC currents flowing through the positive and negative DC input lines and the AC current flowing through the AC output line are mutually canceled out.

[Embodiments of the invention]

FIG. 3 shows a three-phase inverter circuit showing one embodiment of the present invention. In the figure, it has a positive side P line 4 and a negative side N line 5, which are the input part of the DC input line, and a DC filter capacitor C6, a U-phase AC output line U13, which is the output part of the AC output line, and a V-phase AC output line U13, which is the output part of the AC output line. An AC output line V14 and a W-phase AC output line W15 are provided, respectively. 22 is a U-phase inverter stack serving as a phase arm, and this U-phase inverter stack 22 includes transistors TR ₁ 16,
TR ₂ 17 and 23 are V-phase inverter stacks serving as phase arms, and this V-phase inverter stack 23 includes a transistor TR ₃ 18 and a transistor
TR ₄ 19 is a W-phase inverter stack 24 is a phase arm, and this W-phase inverter stack 24 includes a transistor TR ₅ 20 and a transistor
TR ₆ 21 is connected. Reference numerals 25 and 26 denote laminate bars, and the laminate bar 25 is provided between the U-phase inverter stack 22 and the V-phase inverter stack 23, and the laminate bar 26 is provided between the V-phase inverter stack 23 and the W-phase inverter stack 23. The inverter stack 24 is provided between the inverter stack 24 and the inverter stack 24.
Between the U-phase inverter stack 22 and the V-phase inverter stack 23, there is a laminate structure in which the U-phase AC output line U13 is sandwiched between the positive P wire 4 and the negative N wire 5 via an insulator. They are connected by bar 25. Between the V-phase inverter stack 23 and the W-phase inverter stack 24, the U-phase AC output line U13 and the V-phase AC output line V14 are insulated by the positive P line 4 and the negative N line 5. They are connected by a laminate bar 26 with an object in between. The positive side P line 4 and the negative side N line 5 of the DC input section are connected to the U-phase inverter stack 22.
On the side, there is a U-phase AC output line U1 which is the AC output part.
3. The V-phase AC output line V14 and the W-phase AC output line W15 are on the W-phase inverter stack 24 side.

In the inverter circuit configured as described above, the sum of the currents of the U-phase output line U13, the V-phase AC output line V14, and the W-phase AC output line W15 of the AC output section is always zero. Next, in the W-phase inverter stack 24, the transistor TR ₅ 2
0, the transistor TR ₆ 21 is turned on and off alternately, but considering the case where the transistor TR ₅ 20 is turned on first and the transistor TR ₆ 21 is turned off, the output current of the W phase is on the positive side of the DC side power supply line. Transistor from P line 4 via laminate bars 25 and 26
The signal is output through TR ₅ 20 to the W-phase AC output line W15. Therefore, the positive side P line 4 of the laminate bar 26
Since the output current of the W-phase AC output line W15 flows through, ip+iu+iv=0, the current is canceled out, and the magnetic flux is also canceled out. Also, considering the case where the transistor TR ₅ 20 is off and the transistor TR ₆ 21 is on, the output current of the W-phase AC output line W15 passes through the transistor TR ₆ 21 and is connected to the laminate bars 25, 26.
It passes through the negative side N line 5 and returns to the N side. Therefore, the output current of the W-phase AC output line W15 flows through the negative N line 5 of the laminate bar 26, so that iN+iU+
iV=0, the current is canceled out, and the magnetic flux is also canceled out. In this way, the laminate bar 26 becomes a wiring with low inductance.

Next, looking at the V-phase inverter stack 23, as in the W-phase case, the transistor TR ₃ 18
When is on, a V-phase output current flows through the positive P line 4 of the laminate bar 25 and through the transistor TR ₃ 18. When the transistor TR ₄ 19 is on, the V-phase output current passes through the transistor TR ₄ 19, passes through the negative N line 5 of the laminate bar 25, and returns to the DC side. Also, since the W-phase current flows through the positive side P line 4 or the negative side N line 5, ip+iN=iV+iW in the laminate bar 25, so ip+iN+iU
= 0, and the current is canceled out. In this way, the laminate bar 25 also becomes a wiring with low inductance.

As described above, the number of laminate bars 25 and 26 is smaller than the number of phase arms, low inductance wiring can be realized, and the DC section and AC output section can be provided separately.

In the above embodiment, a three-phase inverter circuit was described, but the same effect can be expected even in a single-phase inverter circuit.

FIG. 4 shows another embodiment using a single-phase inverter circuit, in which a laminate bar 27 is provided between a U-phase inverter stack 22 and a V-phase inverter stack 23, which are phase arms. U
The phase inverter stack 22 includes a transistor.
TR ₁ 16, transistor TR ₂ 17, V-phase inverter stack 23 has transistor TR ₃ 18,
Transistors TR ₄ 19 are connected respectively. And between the U-phase inverter stack 22 and the V-phase inverter stack 23, there is a laminate in which the U-phase AC output line U13 is sandwiched between the positive side P line 4 and the negative side N line 5 with an insulator interposed between them. They are connected by bar 27. Positive side P line 4 and negative side N line 5 of DC power supply section
is on the U-phase inverter stack side, and the U-phase AC output line U13 and V-phase AC output line V14, which are AC output parts, are on the V-phase inverter stack 23 side. Since the AC output current is iU + iV = 0, V
Transistor TR ₃ of phase inverter stack 23
18 or transistor TR ₄ 19 turns on,
Since the V-phase output current iv flows through the positive side P line 4 or the negative side N line 5 of the laminate bar 27, the total current in the laminate bar 27 becomes zero.

By the way, in the above embodiment, a laminate bar is provided between the phase arms, and currents in different directions flow through the laminate bar to cancel out the magnetic flux.
The same effect can be obtained no matter which order 6 is placed.

In addition, in the above embodiment, a laminate bar was used in the position of the phase arm, but twisted bars may be used instead of the laminate bar as long as the current flows in the laminate bar and cancels each other out and cancels out the magnetic flux. A similar effect can be achieved using lines. Furthermore, it goes without saying that any material other than the laminated bar or twisted wire may be used as long as the currents cancel each other out and the inductance is low, and the same effect as in the above embodiment can be achieved.

Furthermore, the same effect can be obtained by replacing the inverter stack with a transistor module.

〔Effect of the invention〕

As described above, according to the present invention, the positive and negative DC input lines and AC output lines that cross between a plurality of switching element stacks are insulated via an insulator, and the inductance caused by the flowing current is mutually canceled out. Because they were integrated in parallel to fit,
There is an effect that the inductance of the wiring connecting the plurality of switching element stacks is small.

Further, according to the second invention, the AC output line and the positive and negative DC input lines that cross between the plurality of switching element stacks are laminated with an insulator interposed therebetween to form an integrally formed bar-shaped laminated structure. However, according to the third invention, since the AC output line and the positive and negative DC input lines are insulated and twisted together to form a twisted structure, the inductance of the wiring connecting the plurality of switching element stacks is reduced. This has the effect of being small and having no complicated wiring.

[Brief explanation of the drawing]

Figure 1 is a switching circuit diagram using a general transistor, Figure 2 shows the current and voltage waveforms shown in Figure 1, Figure 2a is a graph of the current waveforms, and Figure 2a is a graph of the current waveforms.
Fig. b is a graph of voltage waveforms, Fig. 3 is a three-phase inverter circuit diagram showing one embodiment of the present invention, Fig. 4 is a single-phase inverter circuit diagram showing still another embodiment of the present invention, FIG. 5 is a circuit diagram of a conventional three-phase inverter. In the figure, 4 is the positive P line of the DC power supply, 5 is the negative N line of the DC power supply, 13 is the U-phase AC output line U, 14 is the V-phase AC output line V, and 15 is the W-phase AC output line. AC output line W, 16, 17, 18, 19, 20, 2
1 is a transistor, 22 is a U-phase inverter stack, 23 is a V-phase inverter stack, 25,
26 and 27 are laminate bars. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. A plurality of switching element stacks having a pair of switching elements connected in series, with both ends of the pair of switching elements serving as positive and negative DC input terminals, and a connection point serving as an AC output terminal. The plurality of switching element stacks have the positive DC input terminal connected in series with a positive DC input line, and the negative DC input terminal connected in series with a negative DC input line,
Each of the AC output terminals is connected with an AC output line, and the DC input line and AC output line connected to each terminal are drawn out in opposite directions, and the AC output line and the positive and negative An inverter circuit characterized in that DC input lines are insulated via an insulator and are integrated in parallel so that inductance due to the flowing current mutually cancels out. 2. Claims characterized in that the AC output lines and the positive and negative DC input lines that cross between a plurality of switching element stacks are laminated with an insulator interposed therebetween to form an integrally formed bar-shaped laminated structure. The inverter circuit according to item 1. 3. The inverter circuit according to claim 1, wherein the AC output line and the positive and negative DC input lines that cross between the plurality of switching element stacks have a twisted structure in which they are insulated and twisted together.