JPH09191683A - Inverter device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the efficiency by controlling the conduction angle variably such that a three-phase inverter sets the conduction waveform of a DC three- phase brushless motor within a specified angle per phase thereby preventing the ON loss and switching loss due to forward voltage drop. SOLUTION: Voltage of an AC power supply 1 is converted into a DC voltage and then passed through an inverter 3 to produce a pseudo AC voltage which is applied to a DC three-phase brushless motor 4. The inverter 3 controls the conduction angle variably such that the conduction waveform per phase will be within 120 deg. in a conduction phase where magnets buried in the rotor of DC three-phase brushless motor perfectly face the field winding of stator at 0 deg. when the waveform is symmetric from -600 deg. to +60 deg. around 0 deg. and from +120 deg. to +240 deg. around +180 deg.. According to the arrangement, motor efficiency can be enhanced by decreasing the number of switching times of inverter 3 without varying the voltage amplitude.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter device for driving a motor such as a compressor of a room air conditioner.

[0002]

2. Description of the Related Art Conventionally, as a method for driving a motor, a voltage type inverter for driving a motor by voltage and a current type inverter for driving a motor have been known. The voltage-type inverter is roughly classified into a PWM drive system and a PAM drive system. FIG. 8A is a configuration diagram of the PWM drive system,
FIG. 8B shows a drive waveform of the same method, FIG. 9A shows a configuration diagram of the PAM drive method, and FIG. 9B shows a drive waveform of the same method. Reference numeral 1 is an AC power supply, 2 is a converter for converting the AC power supply 1 into DC, 3 is an inverter unit for generating pseudo AC applied from DC to the motor, and 4 is a three-phase motor used for a compressor of an air conditioner or the like. The PWM drive method is a method in which the voltage amplitude is substantially constant in FIG. 8 and the waveform is chopped in synchronization with the carrier frequency, and the energization duty is changed to control the power. Further, in FIG. 9A, reference numeral 5 is a voltage drop unit that controls the voltage applied to the inverter unit 3 by using an intermittent means such as PWM. The PAM driving method is a method of controlling the electric power by changing the amplitude of the voltage applied by the voltage drop unit 5 in FIG.

[0003]

However, in the PWM drive system shown in FIG. 8, the electric power applied to the motor 4 can be freely varied, but the switching circuit in the inverter section 3 is large and the switching loss is large. Further, in the motor as well, the high frequency iron loss due to the switching of the inverter section was increased, and there was a limit to the improvement of the total efficiency. Further, in the PAM drive method shown in FIG. 9, high-frequency iron loss of the motor can be suppressed and motor efficiency can be improved by conducting 120 ° energization, while the switching loss of the inverter unit 3 is small, while the voltage drop unit 5 is in order. There is also a problem that ON loss and switching loss occur due to a directional voltage drop, which does not lead to improvement in total efficiency.

The present invention solves the above-mentioned problems of the prior art by eliminating the voltage drop section 5, reducing the switching loss of the inverter section 3 and reducing the high frequency iron loss of the motor 4, thereby reducing the inverter and motor. The purpose is to improve efficiency.

[0005]

In order to solve the above problems, an inverter device of the present invention comprises a converter, a three-phase inverter and a three-phase DC brushless motor. The energization waveform is variably controlled within 120 degrees per phase.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION To solve the above problems, an inverter device of the present invention comprises a converter, a three-phase inverter, and a three-phase inverter.
It consists of a three-phase DC brushless motor, and the energization waveform to the three-phase DC brushless motor by the three-phase inverter is 1
The energization angle is variably controlled within 120 degrees per phase.

Also, in the inverter device of the present invention, the energization waveforms of all three phases are substantially the same.

Further, the inverter device of the present invention is centered around 0 degree in the energization phase where the state in which the magnet embedded in the rotor of the three-phase DC brushless motor and the field winding of the stator are completely opposed to each other is 0 degree. It is symmetrical from 60 degrees to +60 degrees, and symmetrical from +120 degrees to +240 degrees around +180 degrees.

Further, in the inverter device of the present invention, the energization phase is further symmetrical about −30 degrees from −60 degrees to 0 degrees, and 0 degrees to +6 about +30 degrees.
Symmetric up to 0 degrees and +1 around +150 degrees
It is symmetrical from 20 degrees to +180 degrees and symmetrical from +180 degrees to +240 degrees around +210 degrees.

Further, in the inverter device of the present invention, the center of the energization waveform is set to -30 °, + 30 °, +1 of the energization phase.
The conduction angle is set to 50 degrees and +210 degrees, respectively.

Further, in the inverter device of the present invention, the center of the energization waveform is set to -45 degrees, -15 degrees, +1 of the energization phase.
5 degrees, +45 degrees, +135 degrees, +165 degrees, +195 degrees
And the conduction angle is set to +225 degrees.

Further, in the inverter device of the present invention, the energization waveform is different among the three phases.

The inverter device of the present invention is one in which one phase of the energization waveform is energized within 120 degrees.

In the inverter device of the present invention, the period including 0 ° and 180 ° in the energization waveform is turned on.

Further, in the inverter device of the present invention, the center of the energization waveform is set to -30 °, + 30 °, +1 of the energization phase.
The conduction angle is set to 50 degrees, +210 degrees, and ON for a period including 0 degrees and 180 degrees.

Further, in the inverter device of the present invention, the conduction angle of the conduction waveform is set to be variable.

With the above-described structure, the present invention has a relatively simple system structure, does not require the voltage drop unit 5, reduces the switching loss of the inverter unit 3, reduces the high frequency iron loss of the motor 4, and reduces the inverter unit. The overall efficiency of the motor can be improved.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the inverter device of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 is an AC power supply, 2 is a converter for converting the AC power supply 1 into DC, 3 is an inverter for generating pseudo AC applied from a DC to a motor, and 4 is a three-phase used in a compressor of an air conditioner or the like. 3 shows a DC brushless motor.

FIG. 2 shows an induced voltage waveform generated in the stator field winding by the rotation of a rotor incorporating a permanent magnet of a three-phase DC brushless motor (hereinafter referred to as a motor). Normally, the angle between the permanent magnet and the field winding is 0 ° and 180 °
1 in the field winding around 0 ° and 180 °
The motor is driven by energizing the phase width of 20 °. By energizing the motor in accordance with the high phase angle of the induced voltage shown in the figure, a high driving torque and high efficiency of the motor can be obtained.

FIG. 3 is an explanatory diagram of energization waveforms according to the embodiment of the present invention. Although a 120 ° energization method is often used in a motor, the present invention controls the energization angle within 120 ° without using PWM as shown in FIG. As a result, it is possible to control the electric power of the motor without changing the voltage amplitude and reducing the number of switching times of the inverter section. Further, by controlling the energization phase width by setting the center of the energization waveform to 0 ° and 180 °, higher motor efficiency can be obtained.

FIG. 4 is an explanatory diagram of energization waveforms according to another embodiment of the present invention. The energization waveform of each phase of the motor is 120 °
They are shifted and are almost the same. -60 in the figure
The energization phases described as °, -30 °, ..., 240 ° are shown as an example of the U-V phase. By making the three phases the same, unbalance between the phases of the motor can be suppressed, and stable torque and high efficiency can be obtained. Motor 4 is 3
It is a phase winding, and a current flows through two windings with one energization. Therefore, certain conditions are required to make the three phases have the same waveform. In order to satisfy this condition, -60 around 0 °
The symmetry was from ° to + 60 °, and the symmetry was from + 120 ° to + 240 ° around + 180 °. Further, in order to have the same three-phase waveform, -60 ° to 0 ° is symmetrical about -30 °, 0 ° to + 60 ° is symmetrical about + 30 °, and +1.
Symmetrically from + 120 ° to + 180 ° about 50 ° and from + 180 ° to +2 about + 210 °
Symmetry was made up to 40 °. As described above, the same waveform can be supplied to each of the three phases. By making the three phases the same, unbalance between the phases of the motor can be suppressed, and stable torque and high efficiency can be obtained.

Further, in the same figure, the center of the energization phase is -30
The conduction angle was set to each of °, + 30 °, + 150 °, and + 210 °. As a result, the energization phase angle is limited to two times within the energization phase angle of 120 °, and the phase imbalance of the motor is suppressed by making the three phases the same, and the energization phase is divided into two times as compared with FIG. Since the width is widened, the torque ripple during one rotation of the motor can be suppressed, and the switching loss of the inverter unit can be suppressed while obtaining stable torque and high efficiency.

FIG. 5 is an explanatory diagram of energization waveforms according to another embodiment of the present invention. In the figure, the center of the energization phase is -45.
°, -15 °, + 15 °, + 45 °, + 135 °, +1
The conduction angle was set to 65 °, + 195 °, and + 225 °, respectively. As a result, the current is limited to four times within the current phase angle of 120 °, and the phase imbalance of the motor is suppressed by making the three phases the same, thereby increasing the current phase width by dividing the current into four times. It is possible to further reduce the torque ripple during one rotation and to suppress the switching loss of the inverter while obtaining stable torque and high efficiency.

FIG. 6 is an explanatory diagram of energization waveforms of another embodiment of the present invention. The energization waveform of each phase of the motor is different among the three phases. Therefore, the degree of freedom of waveform generation in the inverter section is increased. In the figure, since the U-V phase is energized once every 120 °, it is possible to further reduce the switching loss.

FIG. 7 is an explanatory diagram of energization waveforms of another embodiment of the present invention. By turning ON the period including 0 ° and 180 ° of the energization waveform and energizing during the period of the phase angle having the highest induced voltage shown in FIG. 2, the magnetic flux utilization efficiency is improved and the motor efficiency is improved. Further, the center of the energization waveform was set to -30 °, + 30 °, + 150 °, + 210 ° of the current phase, and the energization angle was set to ON for a period including 0 ° and 180 °. In order to have the same waveform in three phases, energization is performed 5 times as shown in the figure.

As a result, the imbalance between the phases of the motor is suppressed by limiting the energization to five times within the energization phase angle of 120 °, and the three-phase identical waveforms are used, and the energization phase is expanded to 120 ° to achieve the motor 1 It is possible to suppress torque ripple during rotation and obtain higher efficiency while suppressing switching loss in the inverter section.

Further, by varying and setting the respective conduction angles of the conduction waveforms in FIGS. 3 to 7, it is possible to perform electric power control and variable speed of the motor.

[0029]

As is apparent from the above description, the present invention variably controls the energization angle of the motor to within 120 ° per phase so that the voltage amplitude is not changed.
In addition, it is possible to control the electric power of the motor by reducing the number of switching times of the inverter unit.

High efficiency can be obtained by controlling the energizing phase width by setting the center of the energizing waveform to 0 ° and 180 °.

Further, the conduction waveform of each phase of the motor is set to 120 °
The phases are shifted from each other to make them substantially the same. By making the three phases the same, unbalance between the phases of the motor can be suppressed, and stable torque and high efficiency can be obtained.

Further, in order to make the three phases have the same waveform, 0
Symmetric from −60 ° to + 60 ° centering on °,
And + 120 ° to + 240 ° centering on + 180 °
By making the above to be symmetric, it is possible to suppress the unbalance between phases of the motor and obtain stable torque and high efficiency.

Further, in order to make the three phases have the same waveform,
Symmetric from −60 ° to 0 ° about 30 °,
Also, 0 ° to + 60 ° is symmetrical about + 30 °, and + 120 ° to +1 about + 150 °.
Symmetric up to 80 ° and +1 around + 210 °
By making symmetry from 80 ° to + 240 °, it is possible to suppress the phase imbalance of the motor and obtain stable torque and high efficiency.

The center of the energizing phase is -30 °, +30
The energization angles are set to °, + 150 °, and + 210 ° respectively to limit the energization to 2 times within the energization phase angle of 120 °, and to make the three phases the same to suppress the imbalance between the phases of the motor, and to set the energization angle to 2 times. By enlarging the energization phase width by dividing the energization into, the torque ripple during one rotation of the motor can be suppressed, and the switching loss of the inverter unit can be suppressed while obtaining stable torque and high efficiency.

The center of the energization phase is -45 °, -15
°, + 15 °, + 45 °, + 135 °, + 165 °, +
The energization angles are set to 195 ° and + 225 ° respectively to limit the energization to 4 times within the energization phase angle of 120 °, and by making the three phases the same, the phase imbalance of the motor is suppressed and divided into 4 times. By enlarging the energization phase width by the energization, the torque ripple during one rotation of the motor can be suppressed, and the switching loss of the inverter unit can be suppressed while obtaining stable torque and high efficiency.

Further, since the energization waveform of each phase of the motor is different among the three phases, the degree of freedom of waveform generation in the inverter section is increased. In the figure, the U-V phase is energized once every 120 °, and it is possible to further reduce the switching loss.

By turning ON the period including 0 ° and 180 ° of the energization waveform, the period in which the induced voltage shown in FIG. 2 has the highest phase angle is energized, and the magnetic flux utilization efficiency is improved and the motor is improved. Improves efficiency.

Further, the center of the energization waveform is set to the − of the current phase.
By setting the conduction angle to 30 °, + 30 °, + 150 °, + 210 °, and turning on the period including 0 ° and 180 °, the conduction angle is set to 5 within 120 °.
By limiting the energization to one time and using the same waveform for three phases, the phase imbalance of the motor is suppressed and the energization phase width is 120
By increasing the rotation angle to 0 °, the torque ripple during one rotation of the motor can be suppressed and higher efficiency can be obtained while suppressing the switching loss of the inverter section.

Furthermore, by varying and setting the respective conduction angles of the conduction waveform, it is possible to perform power control and variable speed of the motor.

If the present invention is applied to a compressor motor for an air conditioner, the leakage current of the system will be greatly reduced. This is because the leakage current is caused by the electrostatic capacitance between the field winding of the motor and the iron core, and according to the present invention, the number of times of switching is reduced as compared with a PWM type inverter or the like.

As described above, the present invention has a relatively simple system configuration, does not require a voltage drop section, reduces switching loss of the inverter section, reduces high frequency iron loss of the motor, and reduces the inverter section and the motor. It has the effect of improving the overall efficiency.

Further, it has an effect of reducing the leakage current from the motor.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of an inverter device of the present invention.

FIG. 2 is a diagram showing an induced voltage waveform of a three-phase DC brushless motor.

FIG. 3 is an explanatory diagram of an energization waveform according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram of an energization waveform according to another embodiment of the present invention.

FIG. 5 is an explanatory diagram of an energization waveform according to another embodiment of the present invention.

FIG. 6 is an explanatory diagram of an energization waveform according to another embodiment of the present invention.

FIG. 7 is an explanatory diagram of an energization waveform according to another embodiment of the present invention.

FIG. 8A is a configuration diagram of a PWM drive system. FIG. 8B is a diagram showing a drive waveform of the PWM drive system.

FIG. 9A is a configuration diagram of a PAM drive system, and FIG. 9B is a diagram showing drive waveforms of the PAM drive system.

[Explanation of symbols]

 1 AC power supply 2 Converter 3 Inverter section 4 3-phase DC brushless motor 5 Voltage drop section

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Okui 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (11)

[Claims] 1. A converter, a three-phase inverter, and a three-phase DC
An inverter device comprising a brushless motor and variably controlling an energization angle of the energization waveform to the three-phase DC brushless motor by the three-phase inverter within 120 degrees per phase. 2. The inverter device according to claim 1, wherein the energization waveforms of all three phases are substantially the same. 3. A current-carrying phase whose zero is a state where a magnet embedded in a rotor of the three-phase DC brushless motor and a field winding of a stator are completely opposed to each other is centered around zero.
3. The inverter device according to claim 2, wherein symmetry is from 60 degrees to +60 degrees, and symmetry is from +120 degrees to +240 degrees around +180 degrees. 4. The energizing phase is further symmetrical from −60 degrees to 0 degrees around −30 degrees, symmetrical from 0 degrees to +60 degrees around +30 degrees, and +1.
Symmetrically from +120 to +180 degrees around 50 degrees and from +180 to +2 around +210 degrees
The inverter device according to claim 3, wherein the inverter device is symmetrical up to 40 degrees. 5. The center of the current-carrying waveform is the − of the current-carrying phase.
The inverter device according to claim 2, wherein the conduction angles are set as 30 degrees, +30 degrees, +150 degrees, and +210 degrees, respectively. 6. The center of the current-carrying waveform is the − of the current-carrying phase.
45 degrees, -15 degrees, +15 degrees, +45 degrees, +135 degrees,
The inverter device according to claim 2, wherein the conduction angles are set as +165 degrees, +195 degrees, and +225 degrees, respectively. 7. The inverter device according to claim 1, wherein the energization waveform is different among the three phases. 8. The inverter device according to claim 7, wherein one phase of the energization waveform is energized within 120 degrees. 9. The inverter device according to claim 1, wherein a period including 0 degrees and 180 degrees of the energization waveform is turned on. 10. The conduction angle is set by setting the center of the conduction waveform to −30 degrees, +30 degrees, +150 degrees, +210 degrees of the conduction phase, and turning on a period including 0 degrees and 180 degrees, respectively. Inverter device described. 11. The inverter device according to claim 2, wherein the energization angle of the energization waveform is variably set.