JPH01264570A - False sine wave generating method and inverter circuit - Google Patents

Abstract

PURPOSE:To reduce noise level, vibrations and loss by comparing a judgement value level and a fundamental-wave sine wave, determining a semiconductor switching device to be turned ON and generating a false sine wave. CONSTITUTION:An inverter circuit to which a false sine wave generating method is executed is composed of DC powers 1a-1c, semiconductor switching devices (hereinafter called the devices) 2a-2j ON-OFF controlled by a control circuit and rectifiers 3a-3d for preventing reverse currents. The device 2a-2d are constituted in a first pair forming a bridge circuit, the devices 2e-2f, 2h in a second pair respectively connecting each DC power 1a-1c with the bridge circuit BC, and the devices 2g, 2j, 2i in a third pair separately connecting each power 1 in series mutually. Accordingly, a judgement value level and a fundamental-wave sine wave are compared with each other, the device to be turned ON is determined, the false sine wave of a staircase is generated, and a desired staircase wave is applied to the bridge circuit BC.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pseudo sine wave generation method and an inverter circuit in which this method is implemented, particularly an inverter circuit with few harmonic components.

[Conventional technology]

Figure 4 shows, for example, the electrical magazine "OH" published by Ohmsha.
This is a circuit diagram showing the conventional inverter circuit shown in FIG. 2 of MJ, 1987, No. 12, page 26, in which (1) is a DC power supply having an output voltage V, (2a) and (2
b) are semiconductor switching devices connected in series with each other across the DC power supply (1), and (2C)
and (2d) also form a bridge circuit ( BC). The connection point between the semiconductor switching devices (2a) and (2b) is connected to the bridge circuit (B'C) and eventually to one output terminal (01) of the inverter circuit, and the connection point between the semiconductor switching devices (2c) and (2d) is connected to the other output terminal (02) of the inverter circuit, and an output voltage vO is generated between these output terminals (01) and (02).

FIG. 5 is a waveform diagram showing the sine wave/triangular wave comparison method shown in FIG. 3 on page 27 of the above-mentioned "OHM".
O indicates the output voltage.

The conventional inverter circuit is configured as described above, and in the case of triangular wave carrier ec i fundamental wave sine wave es, semiconductor switching devices (2a) and (2d) are
The state is set to N and the semiconductor switching devices (2b) and (2c) are set to OFF.

Semiconductor switching device (2d), DC power supply (1)
A circuit of the semiconductor switching device (2a) is completed, and a voltage of +V is output to the output terminal. triangle wave carrier e
c> In the case of the fundamental sine wave e3, conversely, the semiconductor switching devices (2a) and (2d) are turned off, and the semiconductor switching devices (2b) and (2c) are turned on. Semiconductor switching device (2b)
, DC power supply (1), semiconductor switching device (2c
) circuit is created, and a voltage of -■ is output to the output terminal. As mentioned above, the triangular wave carrier e. and the fundamental sine wave ″e
Compare the size with the semiconductor switching device (
By controlling 2a) to (2d), the output voltage VO
can be a pseudo sine wave.

[Problem to be solved by the invention]

Conventional inverter circuits have a problem in that the output voltage contains many harmonic components, and the harmonics cause large noise, vibration, and loss.

The present invention was made to solve the above-mentioned problems, and an object of the present invention is to provide a method for generating a pseudo sine wave with few harmonic components.

Another invention of this invention is based on harmonics, noise, vibration,
An object of the present invention is to obtain an inverter circuit that can reduce loss.

[Means to solve the problem]

The pseudo sine wave generation method according to the present invention determines a semiconductor switching device to be turned on from among a certain number of body switching devices, and
: Among the N DC power supplies each having a voltage of 2N-1, the DC power supply connected to the turned-on semiconductor switching device generates a staircase wave of 2N-1 steps, and thus a pseudo sine wave.

An inverter circuit according to another invention of this invention has a ratio of 1:2:
・・・・・・・・・・・・：Equipped with N (N or a positive integer of 3 or more) DC power supplies each having a voltage of 2N 1 and 3N+1 semiconductor switching devices, A first set of semiconductor switching devices among the semiconductor switching devices forms a bridge circuit, a second set of semiconductor switching devices connects each DC power source to the bridge circuit, and a third set of semiconductor switching devices forms a bridge circuit. The device consists of DC power supplies connected in series.

[For production]

The conventional technology compares the triangular wave carrier and the fundamental y-wave sine wave.
The semiconductor switching device to be turned on is determined by comparing the value level of the semiconductor switching device to be turned on with the fundamental wave sine wave, and a pseudo sine wave consisting of a staircase wave output voltage is generated.

In another invention of this invention, the first
Half of the semiconductor switching devices of the set are ON during the positive half cycle, the other half of the semiconductor switching devices are ON during the negative half cycle, and the semiconductor switching devices of the second and third sets are at the semi-constant level described above. It is turned on based on the comparison of the fundamental wave sine wave, and a desired step wave is applied from the DC power supply to the bridge circuit.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a circuit diagram showing an inverter circuit in which the pseudo sine wave generation method according to the present invention is implemented, (1a), (1bL
(lc) are output voltages V and 2V, respectively.

(2a) to (2j) are semiconductor switching devices whose ON/OFF control is performed by a control circuit (not shown), and (3a) to (3d) are rectifiers to prevent backflow. be. DC power supply (1a)
is exactly the same as the DC power supply (1) shown in FIG. 4, but it is expressed using a new symbol for convenience of explanation. This DC power supply (1a) is connected to the same bridge circuit (BC) K as shown in FIG. 4 via a semiconductor switching device (2e) and a rectifier (3c) that are connected in series. A semiconductor switching device (2f), a rectifier (3d), a bridge circuit (BC) and a rectifier (3a) are connected between both ends of the DC power supply (1b).
are connected in series. A semiconductor switching device (2h), a bridge circuit (BC), and a rectifier (3b) are connected in series between both ends of the DC power supply (1c). A semiconductor switching device (2g) is connected between the positive terminal of the DC power source (1a) and the negative terminal of the DC power source (1b).
A semiconductor switching device (2j) is connected between the negative terminal of 1c), and a semiconductor switching device (21) is connected between the positive terminal of the DC power supply (1a) and the negative terminal of the DC power supply (IC). is connected.

In other words, semiconductor switching devices (2a) to (2d
) is the first set of semiconductor switching devices forming a bridge circuit, and is a semiconductor switching device (2e).
, (2f), (2h) are each DC power supply (1aL.

(1b), (lc) respectively to a bridge circuit (BC) and a semiconductor switching device (2g).

(2j) and (2i) are between each DC power supply (1a) - (1b
This is a third set of semiconductor switching devices in which L(lb)-(1c) and (la)-(lc')L are connected in series, respectively.

FIG. 2 is a waveform diagram for explaining the operation of the inverter circuit shown in FIG. The waves E1 to E7 are compared in size with the rectified wave ea, and the 0 of the semiconductor switching devices (2a) to (2j) is
It is a judgment value level that determines the timing of N-OFF, and each size is equal to, for example, the maximum value Em divided into a predetermined number, in this case 7, and then multiplied by an integer, that is, E
1=Em/8°]E2=2El, E3=3Ez
,......ET=7E1.

Further, FIG. 3 shows 0 of the semiconductor switching devices (2a) to (2j) in FIG. 1 at each timing in FIG.
It is a diagram showing the N-OFF state, and in the diagram! is ON
× indicates OFF.

Next, the operation of the inverter circuit shown in FIG. 1 will be explained. First, when the fundamental sine wave es is positive, (12a) and (2d) of the semiconductor switching devices forming the bridge circuit (BC) are turned ON, and (
2b) and (2c) are turned OFF. Next, the rectified wave ea
and each of the determination value levels El-E7 are compared as follows and divided into the following eight cases.

(, 1) When 04 rectified wave ea<judgment value level El (10, 114) Ic turns off the semiconductor switching devices (2e) to (2j). DC power supply (1a
) to (1c) are disconnected from the output terminals (01') and (02), so the output voltage vo becomes zero.

(2) Judgment value level E1 ≦ rectified wave ea <judgment value level E
In the case of 1 (tl, tl3), the semiconductor switching device (2e) is turned on. A circuit consisting of a semiconductor switching device (2d), a direct all source (1aL), a semiconductor switching device (2e), a rectifier (3c), and a semiconductor switching device (2a) is created, and the output voltage VO is V.

(3) Judgment value level E2≦rectified wave ea<Judgment value level E
In the case of 3 (H, tt2), the semiconductor switching device (2f) is turned on. A circuit consisting of a semiconductor switching device (2d), a rectifier (3a), a DC power supply (lb), a semiconductor switching device (2f), a rectifier (3d), and a semiconductor switching device (2a) is created, and the output voltage vO is 2v. .

(4) In the case of judgment value level E3≦rectified wave eB, <judgment value level E4 (ts, i+1), the semiconductor switch (
2f), a rectifier (3d), and a semiconductor switching device (2a), and the output voltage yo is 3
It becomes v.

(5) Judgment value level E4≦luxury wave e2<judgment value level E
In the case of 5 (t4.t+o), the semiconductor switching device (2h) is turned on. A circuit consisting of a semiconductor switching device (2d), a rectifier (3b), a DC power supply (IC), a semiconductor switching device (2h) and (2a) is completed, and the output voltage vo is 4V.

(6) Judgment value level E5 ≦ Rectified wave ea Judgment value level E
In the case of 6 (ts, tc+), K turns on the semiconductor switching devices (2h) and (21) and turns off the semiconductor switching device (2g). here,
The semiconductor switching device (2g) is turned OFF' when the semiconductor switching device (2j) is turned ON in the following state (7), that is, the judgment value level E64 rectified wave ea<the judgment value level E7. (1a),
Semiconductor switching device (2g), DC power supply (1b)
), a semiconductor switching device (2j), and a DC power supply (IC). At this time, a circuit consisting of the semiconductor switching device (2d), DC power supply (1a), semiconductor switching device (21), DC power supply (IC), semiconductor switching devices (2h) and (2a) is created.
The output voltage yo will be 5V.

(7) Judgment value level f6≦rectified wave ea<judgment value level E
In the case of 7 (is, js), semiconductor switching devices (2h) and (2j) are turned on. Semiconductor switching device (2d), rectifier (3a) DC power supply (1b)
), semiconductor switching devices (2j), DC power supplies (
IC), semiconductor switching device (2h) and (
A circuit consisting of 2a) is completed, and the output voltage vO is 6V.

(8) In the case of judgment value level E74 rectified wave ea (t7), semiconductor switching devices (2g), (2h).

(2j) is turned ON. Semiconductor switching device (
2d)-1 DC source (1a), semiconductor switching device (2g, ), DC power supply (1b), semiconductor switching device (2''), DC power supply (IC), semiconductor switching device (2h) and (2a) A circuit is completed, and the output voltage vO becomes 7V.

As described above, semiconductor devices (2a) to (
21) can be controlled in eight cases, and by generating seven staircase waves, it is possible to output a positive half cycle of a pseudo sine wave.

When the fundamental sine wave es is negative, conversely, the semiconductor switching devices (2a) and (2d) are turned OFF and the semiconductor switching devices (2b) and (2
After c) is turned on, the same control as in (1) to (8) above is performed to output a negative half cycle.

Note that in the above embodiment, the semiconductor switching device (2
To control ON/OFF of e) to (2j), the control timing was determined by comparing the rectified wave ea of the fundamental sine wave es with the judgment value levels E1 to E7, but the control timing was not memorized in advance. The conductor switching device may be controlled by reading this from a storage device.

Furthermore, although three DC power supplies were used in the above embodiment, if the output voltage is controlled using four or more DC power supplies, the output waveform will become closer to a sine wave, and the effect of reducing harmonic components will be greater. .

Further, in the above embodiments, a transistor was used as the semiconductor switching device, but a thyristor was used as the semiconductor switching device.

GTO, MOSFET, BIMO8, etc. may also be used.

Moreover, although a single-phase circuit is shown in the above embodiment, three such circuits may be used to form a three-phase inverter circuit.

〔Effect of the invention〕

As described above, the present invention compares each of a large number of judgment value levels that increase and decrease with a constant thickness with a rectified wave of a fundamental sine wave, and turns on one of 3N+1 semiconductor switching devices. Determine the semiconductor switching device to be used, 1:2:・・・・・・・・・・・・:2N
Of N DC power supplies each having a voltage of −1,
Since the DC power supply connected to the turned-on semiconductor switching device generates a 2N-1 step staircase wave and, in turn, a pseudo sine wave, it is possible to supply a sine wave with few harmonic components.

Another invention of this invention is 1:2:・・・・・・・・・
...: Equipped with N DC power supplies (N is a positive integer of 3 or more) each having a voltage of 2N-1 and 3N+1 semiconductor switching devices, the first set of semiconductors among these semiconductor switching devices. The switching devices form a bridge circuit, a second set of semiconductor switching devices connects each DC power supply to the bridge circuit, and a third set of semiconductor switching devices connects each DC power supply to a harmonic component obtained by connecting each DC power supply in series. This has the effect of reducing noise, vibration, and loss based on

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an inverter circuit in which the pseudo sine wave generation method according to the present invention is implemented, Fig. 2 is a waveform diagram for explaining the operation of the inverter circuit shown in Fig. 1, and Fig. 3 is a semiconductor switching device. A diagram showing the ON/OFF state of
FIG. 4 is a circuit diagram showing a conventional inverter circuit, and FIG. 5 is a waveform diagram illustrating a sine wave/triangular wave comparison method applied to the conventional inverter circuit. In the figure, (1a) to (1c) are DC power supplies, (2a)
-(2j) are semiconductor switching devices, (BC) is a bridge circuit, ((h), (02) is an output terminal. In the figures, the same reference numerals indicate the same or equivalent parts.

Claims (2)

[Claims] (1) A semiconductor switching device to be turned on among 3N+1 semiconductor switching devices is determined by comparing each of a large number of judgment value levels that increase/decrease at a constant level with a rectified wave of a fundamental sine wave, and 1 :2:・・・・・・・・・
・・・・・・：N each having a voltage of 2^N^-^1
A pseudo sine wave generation method characterized in that a DC power supply connected to an turned-on semiconductor switching device among the DC power supplies generates a 2^N^-^1 step staircase wave and, in turn, a pseudo sine wave. . (2) 1:2:・・・・・・・・・・・・:2^N^-
It is equipped with N DC power supplies (N is a positive integer of 3 or more) each having a voltage of forming a circuit, a second set of semiconductor switching devices respectively connecting each DC power source to the bridge circuit;
An inverter circuit characterized in that a set of semiconductor switching devices connects each DC power supply in series so that a pseudo sine wave is generated between the output terminals of the bridge circuit.