JPH11155299A - Inverter device of two-phase induction motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To vary the revolution of a two-phase induction motor freely, without the use of a capacitor and improve the drive efficiency of the motor easily. SOLUTION: An inverter 15 which has a plurality of circuit switching means, constituted of a first switching unit 20 and a second switching unit 21 which are connected in parallel to each other, first and second DC power supplies 12 and 13 constituted of two DC power supplies which supply powers to both the terminals of the first and second switching units 20 and 21 of the inverter 15 and are connected in series to each other and inverter control units 16 and 41 by which switching devices 14a-14d of which the first and second switching units 20 and 21 are constituted are controlled individually to drive are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter device used for driving a two-phase induction motor widely used in home electric appliances such as electric washing machines and outdoor units of air conditioners today.

[0002]

2. Description of the Related Art Heretofore, when driving the above-described two-phase induction motor, most of the driving systems generally use a capacitor. For example, as shown in FIG. 6, the above-described capacitor operation method includes a main winding (positive-phase side winding) 3 of a two-phase induction motor 2 directly connected to an AC power supply 1 and an AC power supply 1 And an auxiliary winding (90 ° phase-side winding) 5 connected to the power supply.

A power supply voltage is directly applied to the main winding 3 from the AC power supply 1, and a power supply voltage is applied to the auxiliary winding 5 via a capacitor 4. As a result, the current flowing through the auxiliary winding 5 with respect to the current flowing through the main winding 3 is passed by the capacitor 4 as a current having a phase difference of about 90 °. The magnetic field generated by the windings 3 and 5 by energizing the main and auxiliary windings 3 and 5 becomes a rotating magnetic field, and rotates the rotor 6.

[0004] In place of the method of driving the two-phase induction motor using a capacitor, for example, two single-phase transformers are connected by a Scott connection, and a three-phase transformer is used by using the Scott connection. It is also possible to drive a two-phase induction motor by obtaining a two-phase AC power supply from an AC power supply.

[0005]

However, in the system in which the two-phase induction motor is driven by using a capacitor,
When the characteristics of the capacitor itself change during long-term use, the rotation of the motor itself may be stopped, or a large current may flow through the motor, causing the coil to generate heat and causing a burnout accident.

Further, with the change in the characteristics of the capacitor, 9
There is also a problem that the drive efficiency of the two-phase induction motor is significantly reduced due to the change of the 0 ° phase difference. Moreover,
When the two-phase induction motor is operated at a variable speed, in order to vary the frequency of the single-phase AC power supply, prepare a plurality of capacitors connected to the auxiliary winding side, and adjust them according to the change in the frequency of the single-phase AC. It is very troublesome because it is necessary to select and switch a capacitor that matches the frequency,
It was uneconomic.

Further, when a two-phase induction motor is driven by a two-phase AC power source obtained via a Scott connection from a three-phase AC power source, the two-phase AC power source is supplied from a three-phase AC power source having a fixed frequency. Therefore, there is a fundamental problem that the rotation speed of the two-phase induction motor cannot be varied.

[0008]

SUMMARY OF THE INVENTION The present invention relates to an inverter apparatus in which a two-phase induction motor is driven by an inverter without an intervening capacitor.
Provided with a circuit switching means composed of a plurality of switching elements constituted by connecting the switching unit and the second switching unit in parallel, and supplying the voltage to both ends of the first and second switching units of the inverter. A first and a second DC power supply formed by connecting two DC power supplies in series;
Furthermore, an inverter control unit for individually controlling the driving of the switching elements forming the first and second switching units is provided.

Further, the inverter control unit used in the present invention includes a signal unit for conducting a plurality of switching elements constituting the first and second switching units in a predetermined phase section, respectively, by a square wave signal and a sine wave signal. Is output.

According to the present invention, since the two-phase alternating current generated by the inverter is directly supplied to the main winding and the auxiliary winding of the two-phase induction motor for driving, no capacitor is required, and the inverter is driven. In this case, since the inverter itself is configured to be drive-controllable using a square wave and a sine wave, in the former (drive using a square wave), the rotation speed of the motor can be changed, and in the latter (drive using a sine wave), In (2), the driving efficiency of the motor itself can be significantly improved.

[0011]

FIG. 1 is a block diagram showing an embodiment of the present invention.
This will be described with reference to FIG. In FIG. 1, an inverter device 11 according to the present invention includes first and second DC power supplies 12 and 13.
And switching elements 14a-1
4d, and an inverter control unit 16 for supplying a control signal to the inverter 15. An output terminal of the inverter device 11 has a main winding (positive-phase side winding) 17 and an auxiliary winding. Wire (90 ° phase side winding)
18 is connected.

Next, the detailed structure of the inverter device 11 will be described. First, the inverter 15 includes a first switching element 14a and 14b connected in series.
And the switching element 14
c, 14d, a second switching unit 2 connected in series
1. The first and second switching units 20 and 21 are connected in series to the first and second switching units 20 and 21.
The respective bases of the switching elements 14 a to 14 d constituting the respective switching units 20 and 21 are connected to the respective output terminals of the inverter control unit 16. ing.

Furthermore, the main winding 17 of the two-phase induction motor 19
Is a connection point a of a series connection of the switching elements 14a and 14b constituting the first switching unit 20.
, And the other is connected to a connection point b, which is a series connection of the first and second DC power supplies 12 and 13. The auxiliary winding 18
Is connected to a connection point c which is a series connection part of the switching elements 14c and 14d of the second switching unit 21, and the other is connected to the other of the main winding 17 at a connection point d. And a connection point b of the DC power supplies 12 and 13 are connected using, for example, a common line e.

In FIG. 1, a connection point a of the first switching unit 20 and a connection point b of the DC power supplies 12 and 13 are connected.
An output (positive-phase side winding voltage e ₁ ) having a phase corresponding to a single-phase alternating current obtained between the main winding 17 of the two-phase induction motor 19 and the second switching unit output 21 of phase relative to the positive-phase winding voltage e ₁ obtained between the connecting point c to the connection point b is provided with a phase corresponding to the AC 90 ° different single phase (phase winding voltage e ₂ ) to the auxiliary winding 18.

Next, the configuration of the inverter control section 16 for controlling the drive of the inverter 15 will be described with reference to FIG. The inverter control unit 16 outputs a pulse signal for turning on each of the switching elements 14a to 14d of the inverter 15 in a required phase section within a range of a phase in a half cycle cycle of a single-phase AC having a required frequency. It is configured.

That is, for example, the pulse signal 30 output from the inverter control section 16 shown in FIG. 1 is generated by switching the switching element 14a of the first switching section 20 to 45 as shown in the waveform diagram (square wave) shown in FIG. The pulse signal 33 causes the switching element 14d of the second switching unit 21 to be turned on in the 135 ° -225 ° phase section.
The pulse signal 31 makes the switching element 14b of the first switching section 20 conductive in the phase section of 225 ° to 315 °, and the pulse signal 32 makes the switching element 14b of the second switching section 21 conduct. The inverter control unit 16 is configured to perform a switching operation so that the switching element 14c can be turned on in a phase section of 315 ° to 45 °.

The switching units 20, 21
Signals 30 to 33 for switching operation of
Are output in a predetermined order, for example, as shown in FIG. 2, a clock circuit 22 that outputs a clock signal at a constant cycle (a cycle corresponding to a cycle of each 90 ° phase section), A counter circuit 23 having a function of resetting when four signals are counted, and flip-flop circuits FF ₁ to FF which turn on and off in response to a predetermined number of pulses output from the counter circuit 23
It is constituted by the F _4.

In the inverter control section 16, the counter circuit 23 outputs ₁ from the flip-flop circuit FF1.
Number counted turns on during the pulse PS ₁ to be output at the time of resetting, and outputs a pulse signal 30 turns off the clock circuit 22 by the input of the next clock pulse.

The flip-flop circuit FF ₂ is turned on by a pulse PS ₂ output when the counter circuit 23 counts and resets _{two, and is} turned off by the input of the next clock pulse to output a pulse signal 33. .

Furthermore, the flip-flop circuit FF _3, the counter circuit 23 are three counted turns on during the pulse PS ₃ outputs when reset, the pulse signal 31 turns off the input of the next clock pulse Output.

[0021] In addition, from the flip-flop circuit FF _4,
The counter circuit 23 is turned on by a pulse PS4 output when the counter circuit 23 counts and resets _{four, and is} turned off by the input of the next clock pulse to output a pulse signal 32.

[0022] As described above, by repeating the counting counter circuit 23 is reset again, in response to the pulse PS ₁ ~PS ₄ to the flip-flop circuits FF ₁ to ff ₄ are sequentially outputted from the counter circuit 23 The operation is repeated as described above, whereby the pulse signals 30 to 33 are output from the inverter control unit 16 to the predetermined switching elements 14 a to 14 d of the inverter 15.
Drive control. As a result, the output interval of the pulses PS _{1 to} PS ₄ output from the counter circuit 23 is varied by the input period of the clock pulse input to the counter circuit 23, so that the main winding 17 and the auxiliary winding 18 The applied voltage frequency can be changed arbitrarily.

By providing the inverter control unit 16, the inverter 15 can operate the main winding 1 of the two-phase induction motor 19.
7, for example, as shown in FIG. 3, a positive-phase AC voltage of positive and negative square waves such as a positive-phase winding voltage e ₁ is directly supplied to the auxiliary winding 18. Figure 3
The two-phase induction motor 19 is driven by directly supplying a 90 ° phase alternating voltage of positive and negative square waves such as the 90 ° phase side winding voltage e ₂ shown in FIG.

That is, the operation of the inverter 15 will be described in more detail. The output of the pulse signal 30 from the inverter control unit 16 causes the first switching unit 2
0 when the switching element 14a is turned on, the power supply 12-
A current flows along the path of the switching element 14a-the main winding 17-the power supply 12 along the X direction in FIG. Subsequently, when the pulse signal 33 is output from the inverter control unit 16, the switching element 14d of the second switching unit 21 conducts, and the power supply 13 and the auxiliary winding 1 are turned on.
A current flows along the Y ′ direction shown in FIG.

Further, the switching element 14b of the first switching section 20 is turned on by the output of the pulse signal 31 from the inverter control section 16, and the power supply 13-main winding 17-
A current flows in the Y direction through the path between the switching element 14 b and the power supply 13, and is supplied to the main winding 17. When the pulse signal 32 is output from the inverter control unit 16, the switching element 14c of the second switching unit 21 conducts,
A current flows in the X ′ direction through the path of the power supply 12, the switching element 14 c, the auxiliary winding 18, and the power supply 12, and the current flows through the auxiliary winding 18.

As described above, in the inverter device 11 according to the present invention, each of the switching elements 14a to 14d of the inverter 15 is formed into a simple 90 ° step square by the pulse signals 30 to 33 output from the inverter control unit 16. Since it can be driven using only waves,
The two-phase induction motor 19 can be satisfactorily driven by a quasi-single-phase alternating current as compared with sinusoidal single-phase alternating currents e ₁ S and e ₂ S as shown in FIG.

As a result, the single-phase alternating current generated by the inverter device 11 is directly applied to the main winding (positive-phase winding) 17 and the auxiliary winding (90 ° phase-side winding) 1 of the two-phase induction motor.
8, the two-phase induction motor 19 can be driven without a capacitor,
By changing the switching frequency of the inverter 15, it is possible to easily change the rotation speed and drive.

Further, the inverter device 11 enables the switching section 20 for the main winding 17 and the switching section 21 for the auxiliary winding 18 of the two-phase induction motor 19 to be switched to each other so as to be energized. Switching units 20, 21
, And the two-phase induction motor 19 can be driven by the two DC power supplies 12 and 13, so that the inverter 15 is configured using the minimum number of switching elements 14a to 14d. It is possible to economically manufacture with a simple configuration and it is convenient.

Next, the inverter device 11 sends predetermined square wave pulse signals 30 to 21 to predetermined switching units 20 and 21.
By outputting 33 and obtaining a quasi-single-phase alternating current,
Although an example has been described in which the two-phase induction motor 19 can be driven so that the speed can be controlled, the present invention is not limited to this, and a predetermined AC signal (current) is supplied from the inverter control unit 41 to the inverter 15 shown in FIG. A method for efficiently driving the two-phase induction motor 19 by outputting the output will be described as a second embodiment of the present invention.

In this case, as in the first embodiment,
Instead of using a square wave, an output having a sine wave of an AC signal as shown by e ₁ S and e ₂ S in FIG. 3 is output from the inverter 15 to the main winding 17 and the auxiliary winding of the two-phase induction motor 19. By supplying the power to the line 18, the pulsation of the rotational torque of the two-phase induction motor 19 can be suppressed well, and the silent drive can be realized.

For example, the inverter control unit 41 shown in FIG.
The sine wave signal 30 ′ shown in FIG. 1 output from the inverter 15 to the inverter 15 conducts the switching element 14a of the first switching unit 20 in the phase section of 0 to 180 ° as shown in the waveform diagram of FIG. The sine wave signal 33 ′ causes the switching element 14 d of the second
Conducted in the phase section of ~ 270 °, the sine wave signal 3
1 ′ conducts the switching element 14b of the first switching unit 20 in a phase section of 180 ° to 360 °, and the sine wave signal 32 ′ causes the switching element 14c of the second switching unit 21 to conduct the switching element 14c of 270 ° to 360 °. The inverter control unit 41 is configured to be able to perform a switching operation so that conduction can be performed in a phase section of 90 °.

In this case, for example, the sine wave signal 30 'shown in FIG. 1 output from the inverter control unit 41 shown in FIG. 4 to the inverter 15 is obtained by switching the switching element 14a of the first switching unit 20 to the waveform shown in FIG. 0 ° ~
Conducts in the phase section of 180 °, and the sine wave signal 33 ′
Is the switching element 14 of the second switching unit 21
d is conducted in the phase section of 90 ° to 270 °, and the sine wave signal 31 ′ conducts the switching element 14b of the first switching section 20 in the phase section of 180 ° to 360 °. 'Sets the switching element 14c of the second switching unit 21 to 270 ° to 90 °.
The inverter control unit 41 is configured to be able to perform a switching operation so that conduction can be performed in a phase section of °.

FIG. 4 is a schematic diagram of an inverter control unit 41 for driving and controlling the inverter 15. The inverter control unit 41 operates the first switching elements 14a and 14c on the upper arm side of the inverter 15 shown in FIG. The command circuit 42 and the switching elements 14b, 14 on the lower arm side
d, the output terminals of the first and second command circuits 42 and 43 are respectively connected to predetermined switching elements 14a to 14a as shown in FIG.
4d.

The first command circuit 42 includes an AC power supply 44
A step-down circuit 45 comprising a step-down transformer or the like for stepping down the input voltage to a predetermined voltage, a delay circuit 46 for shifting the output of the step-down circuit 45 by 90 °, and a half-wave output from the delay circuit 46. A half-wave rectifier circuit 47 for rectifying, a dead time generating circuit 48 for preventing the switching elements 14a and 14c forming the upper arm of the inverter 15 and the switching elements 14b and 14d forming the lower arm from being short-circuited;
Further, the voltage / current conversion circuit 4 converts the voltage output from the dead time creation circuit 48 into a current corresponding to the voltage.
9, the output terminal of the first command circuit 42 is connected to the switching elements 14a, 14a of the inverter 15.
Connect to c.

Next, the second command circuit 43 is basically the same as the first command circuit 42 except that a delay circuit 46a and a half-wave rectifier circuit 47a 4
This second command is different only in that a phase inverting circuit 50 having a function of further inverting the phase shifted by 90 ° in 6a and enabling driving of the switching elements 14b and 14d on the lower arm side is inserted. The output terminal of the circuit 43 is connected to the switching elements 14b and 14d. And
Except for the phase inversion circuit 50, the step-down circuit 45a, the phase delay circuit 46a, and the half-wave rectifier circuit 4 which constitute the second control circuit 43
7a, the dead time creation circuit 48a, and the voltage / current conversion circuit 49a are configured in the same manner as the first control circuit 42, and thus description thereof is omitted.

As described above, the inverter control section 41 outputs a sine wave signal from the output terminal thereof to each of the switching elements 14a to 14d of the inverter 15, and conducts these switching elements 14a to 14d for a predetermined time (fixed) to thereby conduct. , Sinusoidal signals 30 ′, 3
A current having a sine waveform is output according to a current waveform having a sine waveform of 1 ′, 32 ′, and 33 ′, and the starting torque and the operating torque of the two-phase induction motor 19 are increased without performing speed control. It is possible to drive efficiently.

That is, the drive control of the inverter 15 by using the inverter control unit 41 means that the phases of the main winding 17 and the auxiliary winding 18 of the two-phase induction motor 19 are shifted by 90 °,
A current having the same amplitude can flow (a sine wave having the same amplitude and a cos wave whose phase is shifted by 90 ° can be applied to the base of the switching element), whereby the amplitude of the magnetic flux in the rotating magnetic field is made uniform ( (A magnetic circle magnetic field), and the two-phase induction motor 19 can be efficiently driven.

On the other hand, in a conventional two-phase induction motor using a capacitor, the phase of the current flowing through the winding is shifted due to the combined impedance consisting of the resistance value and the reactance of the winding, whereby the true magnetic flux is generated. It was difficult to form a circular magnetic field, and it was difficult to increase efficiency. As a result, in order to obtain a perfect circular magnetic field of the magnetic flux, it is not possible to control the phase of the current to always be 90 ° and to control the amplitude of the magnetic flux between the main winding and the auxiliary winding to be equal. Was. However, if the inverter 15 is controlled using the inverter control unit 41, the main winding 17 and the auxiliary winding 1 are controlled.
8, an electric current having the same amplitude can be applied to the windings 17, 18 so that an alternating magnetic field is generated in both windings 17 and 18, and a magnetic flux is generated on the secondary side of the windings in a direction to cancel the alternating magnetic field. A current flows so as to generate the magnetic field, and a magnetic field generated in a direction to cancel the alternating magnetic field can generate a perfect circular magnetic field. As a result, the driving efficiency of the two-phase induction motor 19 is greatly increased as compared with the case where a capacitor is used. Can be improved.

[0039]

As described above, according to the present invention, not only the operation of the two-phase induction motor can be performed without the presence of the capacitor, but also the accident during the operation (motor stop, Short-circuit fire) can be eliminated, and moreover, the efficiency of the motor can be improved and the quiet operation can be improved. Therefore, it is possible to contribute to power saving of home electric appliances (refrigerator using AC motor, outdoor unit of air conditioner, and the like).

Further, the inverter device of the present invention can be constituted by combining four switching elements and two DC power supplies, so that not only the structure can be simplified but also economical production is possible. Become. In addition, by controlling the drive of the inverter itself using a square wave or a sine wave, the former can change the rotation speed, and the latter makes it possible to use the motor itself more efficiently. It also has the advantage of being able to expand significantly.

[Brief description of the drawings]

FIG. 1 is a main part connection configuration diagram showing an inverter device of the present invention.

FIG. 2 is a main part block configuration diagram showing a first embodiment of an inverter control unit.

FIG. 3 is a signal waveform diagram in the first embodiment of the inverter control unit.

FIG. 4 is a block diagram showing a main part of a second embodiment of the inverter control unit.

FIG. 5 is a signal waveform diagram output from the inverter control unit of the second embodiment.

FIG. 6 is a diagram showing a main part connection configuration of a conventional two-phase induction motor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Inverter apparatus 12 1st direct-current power supply 13 2nd direct-current power supply 14a-14d Switching element 15 Inverter 16,41 Inverter control part 17 Main winding 18 Auxiliary winding 19 Two-phase induction motor 20 1st switching part 21 2nd Switching section

Claims (4)

[Claims] In an inverter device in which a two-phase induction motor is driven by an inverter without an intervening capacitor, a plurality of switching devices configured by connecting a first switching unit and a second switching unit in parallel are provided. An inverter including circuit switching means composed of elements, first and second DC power supplies formed by connecting in series two DC power supplies to both ends of first and second switching units of the inverter, and And an inverter control section for individually controlling the driving of the switching elements constituting the first and second switching sections. 2. An inverter apparatus for a two-phase induction motor, comprising: 2. A connection point of the first and second DC power supplies, wherein a common connection point of a main winding and an auxiliary winding of a two-phase induction motor is connected by a common line. 2. The inverter device for a two-phase induction motor according to claim 1. 3. The method according to claim 1, wherein the inverter control unit includes first and second inverters.
2. A method of outputting a square wave signal for conducting a plurality of switching elements constituting the switching unit in a predetermined phase section.
An inverter device for the two-phase induction motor according to the above. 4. The method according to claim 1, wherein the inverter control unit includes first and second inverters.
2. The inverter device for a two-phase induction motor according to claim 1, wherein a sine wave signal for continuously conducting a plurality of switching elements constituting said switching unit in a predetermined phase section is output.