JPH02188189A - Inverter for pulse width modulation type single-phase motor - Google Patents

Abstract

PURPOSE:To simplify the constitution of an apparatus and reduce its cost by connecting both ends of the main winding of a single-phase motor between two pairs of semiconductor switches turned ON and OFF alternately of first and second circuits and by connecting the intermediate tap of a transformer connected between the auxiliary winding of said single-phase motor and the intermediate part between said semiconductor switches of the first circuit with the voltage-dividing point of a DC power supply. CONSTITUTION:First circuit 24 and second circuit 25 respectively series-connecting two pairs of semiconductor switches (26, 27), (28, 29) turned ON and OFF alternately are furnished in parallel with each other, both ends of the main winding 22 of a single- phase motor 21 are connected between respective semiconductor switches (26, 27), (28, 29) of said first circuit 24 and second circuit 25, a transformer 30 is connected between the auxiliary winding 23 of said single-phase motor 21 and the intermediate part between said semiconductor switches 26, 27 of the first circuit 24, and the intermediate tap of said transformer 30 is connected with the voltage-dividing point of a DC power supply 20. Thus, the number of semiconductor switches decreases to 4 so that the constitution of an apparatus can be simplified and its cost can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an inverter for a pulse width modulated single-phase motor.

(Prior art) A pulse width modulation type motor inverter, which adjusts the output voltage and output frequency by turning a semiconductor switch on and off many times using a pulse width modulation signal, has been known for use in three-phase motors. .

That is, FIG. 8 shows the basic circuit of a three-phase pulse width modulation type inverter, in which each transistor 1, 2, 3, 4, 5, 6 is turned on and off every half cycle by a pulse width modulation signal, and the A three-phase AC voltage is supplied to the phase motor 8. The pulse width modulation signal is transmitted to each transistor 1, 2, 3, 4.
．． 5 and 6, the pulse generating circuit has many fundamental wave components of the inverter output voltage, and is equivalently close to a sine wave.

If the voltages at points A, B, and C in Fig. 8 are shown as vectors, they are equivalent to voltages whose phases are shifted by 120° as shown in Fig. 9. By applying voltages whose phases are shifted by 120 degrees to each winding, a rotating magnetic field is generated and the three-phase motor 8 can be rotated. This applies to both the star connection shown in FIG. 8 and the delta connection shown in FIG.

In addition, each vector voltage U, V between AB, BC, and CA
, W are also shifted by 120°.

In the case of a single-phase motor 9, when voltages with a phase difference of 90° are applied to the main winding 10 and the auxiliary winding 11, a rotating magnetic field is generated and the motor rotates, so each winding 10 and 11 is shown in FIG. If connected as shown in Figure 12, the voltage at point C will be a vector in the opposite direction to the voltage at point A, so vector voltages U and X will be orthogonal, and therefore a three-phase inverter can be used as is. The single-phase motor 9 can be rotated.

(Problem to be Solved by the Invention) However, although the circuit shown in FIG. 11 can be used for the single-phase motor 9, it requires six semiconductor switches, that is, six transistors, so the circuit shown in FIG. Ancillary circuits must be provided for each of the transformer and the transistor, and therefore, although it is a single-phase motor 9, the structure is complicated and expensive.

In view of such conventional problems, an object of the present invention is to reduce the number of semiconductor switches by utilizing the fact that it is a single-phase motor, and to enable simple and inexpensive implementation.

(Means for Solving the Problems) As a first means for solving the problems, the present invention provides a first circuit 24 and a second circuit formed by connecting in series two semiconductor switches 26, 27, 28, and 29 that are turned on and off alternately. circuit 25 in parallel, and both ends of the main winding 22 of the single-phase motor 21 are connected to semiconductor switches 26, 27, .
28 and 29, and the auxiliary winding 23 of the single-phase motor 21
A transformer 30 is connected between the semiconductor switches 26 and 27 of the first circuit 24, and the intermediate tap of the transformer 30 is connected to the voltage dividing point of the DC power supply 20.

As a second problem-solving means, a first circuit 24 and a second circuit 25 are provided in parallel, each consisting of two semiconductor switches 26, 27, 28, and 29 connected in series, which are turned on and off alternately. Each semiconductor switch 26.27.28.2 connects both ends of the main winding i%m22 to the first circuit 24 and the second circuit 25.
9, a transformer 30 is connected in parallel to the main winding 22, and both ends of the auxiliary winding 23 of the single-phase motor 21 are connected to the transformer 3.
0 intermediate tap and the voltage dividing point of the DC power supply 20.

As a means for solving the third problem, a first circuit 24 and a second circuit 25 each consisting of two semiconductor switches 26, 27, 28, and 29 connected in series, which are turned on and off alternately, are provided in parallel, and the single-phase motor 21 Both ends of the main winding 22 are connected to the first circuit 24 and the second circuit 24.
Each semiconductor switch 26.27.28.29 with circuit 25
Both ends of the auxiliary winding 23 of the single-phase motor 21 are connected to the intermediate tap of the main winding 22 and the voltage dividing point of the DC power supply 20.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a circuit diagram showing a first embodiment of the present invention;
The figure shows the vector diagram. In Figure 1, 20 is a DC power supply, 21 is a single-phase motor, and the main winding 22 and the auxiliary winding 2
3. 24 is the first circuit, 25 is the second circuit,
These are transistors 26.2 as semiconductor switches.
7.28.29 are connected in series, and are connected in parallel to each other. These circuits 24.
A, B between 25 transistors 26, 27, 28, 29
Both ends of the main winding 22 of the single-phase motor 21 are connected to the point. 30 is a transformer, and the transistor 2 of the first circuit 24
It is connected between point A between 6.27 and the auxiliary winding 23 of the single-phase motor 21. The transformer 30 has an intermediate tap at a position where the winding ratio is 1=1, and this intermediate tap is connected to a voltage dividing point of the DC power supply 20 divided into two.

With this configuration, the transistor 2 of the first circuit 24
6.27 turns on and off alternately, DC power supply 2
As shown in FIG. 2, a current flows from zero to the transformer 30, and as shown in FIG.
, the single-phase motor 21 rotates. Therefore,
Since the number of transistors is reduced to four compared to the conventional one, the configuration including the attached circuits is simplified and can be implemented at low cost.

FIG. 3 shows a second embodiment of the present invention, in which the DC power supply 20 has two
Connect capacitors 31 and 32, and the capacitor 3
The intermediate tap of a transformer 30 is connected between 1 and 32. In this way, the voltage of the DC power supply 20 may be divided by the capacitors 31 and 32.

FIG. 4 shows a third embodiment of the present invention. In this way, a transformer 30 is connected in parallel to the main winding 22 of the single-phase motor 21, and both ends of the auxiliary NlA 23 of the single-phase motor 21 are connected to the transformer 30. It may be connected to the intermediate tap E and the voltage dividing point of the DC power supply 20. With this configuration, the voltage at the intermediate tap E of the transformer 30 becomes a vector as shown in FIG. 5, and the voltage at the auxiliary winding 23 can be shifted by 90 degrees with respect to the main winding 22. In other words, vector AB and vector D
E will be orthogonal.

FIG. 6 shows a fourth embodiment of the present invention, in which a main winding 22 of a single-phase motor 21 is used, and the main winding 22 has a winding ratio of 1:
An intermediate tap E' is provided at the position 1, and an auxiliary winding 23 is connected to this intermediate tap E°. In this case as well, as shown in FIG. 7, the vector DE'' of the voltage at point E° is orthogonal to the vector AB, so the single-phase motor 21 can be rotated. is no longer necessary and can be implemented at a lower cost.

(Effects of the Invention) The first means of the present invention includes a first circuit 24 and a second circuit 25 in parallel, which are formed by connecting two semiconductor switches 26, 27, 28, and 29 in series that are turned on and off alternately. , both ends of the main winding 22 of the single-phase motor 21 are connected between the respective semiconductor switches 26, 27, 28, 29 of the first circuit 24 and the second circuit 25, and the auxiliary winding 23 of the single-phase motor 21 and the 1 circuit 24
A transformer 30 is connected between the semiconductor switches 26 and 27, and the intermediate tap of this transformer 30 is connected to the DC power supply 20.
Since it is connected to the voltage dividing point, the number of semiconductor switches is reduced to four, and the configuration is simple and can be implemented at low cost.

Further, in a second embodiment of the present invention, a first circuit 24 and a second circuit 25 each formed by connecting two semiconductor switches 26, 27, 28, 29 that are turned on and off alternately in series are provided in parallel, and a single-phase motor Both ends of the main winding 22 of 21 are connected to the first circuit 24 and the second circuit 24.
Each semiconductor switch 26.27.28.29 with circuit 25
The transformer 30 is connected in parallel to the main winding 22, and both ends of the auxiliary winding 1+I23 of the single-phase motor 21 are connected to the intermediate tap of the transformer 30 and the voltage dividing point of the DC power supply 20. As in the case described above, the configuration is simple and can be implemented at low cost.

Furthermore, in the third means of the present invention, a first circuit 24 and a second circuit 25 each formed by connecting two semiconductor switches 26, 27, 28, 29 that are turned on and off alternately in series are provided in parallel, and the single-phase motor Both ends of the main winding 22 of 21 are connected to the first circuit 24 and the second circuit 24.
Each semiconductor switch 26, 27, 28, 29 with circuit 25
Since both ends of the auxiliary part m23 of the single-phase motor 21 are connected to the intermediate tap of the main winding 22 and the voltage dividing point of the DC power supply 20, the transformer 30 in each of the above means is unnecessary. It can be implemented inexpensively.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing a first embodiment of the present invention, Fig. 2 is a vector diagram thereof, Fig. 3 is a circuit diagram showing a second embodiment of the invention, and Fig. 4 is a circuit diagram showing a third embodiment of the invention. A circuit diagram showing an example, FIG. 5 is the same vector diagram, FIG. 6 is a circuit diagram showing the fourth embodiment of the present invention, FIG. 7 is the same vector diagram, FIG. 8 is a conventional royal circuit diagram, FIG. 9 is a vector diagram of the same, FIG. 10 is a wiring diagram of a three-phase motor, FIG. 11 is a circuit diagram of a conventional single-phase motor, and FIG. 12 is a vector diagram of the same. 20...DC power supply, 21...Single-phase motor, 22...
- Main winding, 23... Auxiliary winding, 24... First circuit,
25...Second circuit, 26-29...Transistor (
semiconductor switch), 30...transformer. Figure 3 Day χ 4 Cause Figure 6 Figure 8 @ 17 Figure 2 Figure 10 Figure 5 Figure 12

Claims (3)

[Claims] (1) In a pulse width modulated single-phase motor inverter that turns on and off a semiconductor switch using a pulse width modulation signal and supplies AC voltage from a DC power supply (20) to a single-phase motor (21), the semiconductor switch is turned on and off alternately. A first circuit (24) and a second circuit (25) each consisting of two semiconductor switches (26), (27), and (28) and (29) connected in series are provided in parallel, and the single-phase motor (21) is Both ends of the main winding (22) are connected between the semiconductor switches (26), (27), (28) and (29) of the first circuit (24) and the second circuit (25), and the single-phase motor (21 ) A transformer (30) is connected between the auxiliary winding (23) of the semiconductor switch (26) and (27) of the first circuit (24), and the intermediate tap of this transformer (30) is connected to the DC power supply (20 ) A pulse width modulation type single-phase motor inverter characterized by being connected to the voltage dividing point of ). (2) In a pulse width modulated single-phase motor inverter that turns on and off a semiconductor switch using a pulse width modulation signal and supplies AC voltage from a DC power supply (20) to a single-phase motor (21), the semiconductor switch is turned on and off alternately. A first circuit (24) and a second circuit (25) each consisting of two semiconductor switches (26), (27), and (28) and (29) connected in series are provided in parallel, and the single-phase motor (21) is Both ends of the main winding (22) are connected between the semiconductor switches (26), (27), (28) and (29) of the first circuit (24) and the second circuit (25), and the main winding (22) ), and both ends of the auxiliary winding (23) of the single-phase motor (21) are connected to the intermediate tap of the transformer (30) and the voltage division point of the DC power supply (20). A pulse width modulation single-phase motor inverter featuring: (3) In a pulse width modulated single-phase motor inverter that turns on and off a semiconductor switch using a pulse width modulation signal and supplies AC voltage from a DC power supply (20) to a single-phase motor (21), the semiconductor switch is turned on and off alternately. A first circuit (24) and a second circuit (25) each consisting of two semiconductor switches (26), (27), and (28) and (29) connected in series are provided in parallel, and the single-phase motor (21) is Both ends of the main winding (22) are connected between the semiconductor switches (26), (27), (28) and (29) of the first circuit (24) and the second circuit (25), and the single-phase motor (21 ) A pulse width modulation type single-phase motor inverter, characterized in that both ends of the auxiliary winding (23) of the main winding (22) are connected to the intermediate tap of the main winding (22) and the voltage dividing point of the DC power supply (20).