JP2001238484A - Inverter device - Google Patents

Abstract

(57) [Problem] To provide an inverter device used for a brushless motor, a reluctance motor, and an induction motor that performs low vibration and low noise operation. SOLUTION: The present invention analyzes a time harmonic component of a trapezoidal wave voltage or a pseudo sine wave voltage in which a rising portion and a falling portion of the trapezoidal wave are sine waves by a Fourier series, and obtains an optimal trapezoidal wave voltage waveform. Another object of the present invention is to provide an inverter device that performs a motor operation with an optimum pseudo sine wave voltage waveform. As a result, it is possible to obtain an inverter device that operates the motor with low vibration and low noise.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an inverter device for optimally controlling a BL motor, a reluctance motor, and an induction motor.

[0002]

2. Description of the Related Art Conventionally, a synchronous motor (hereinafter, abbreviated as a brushless motor) using a permanent magnet as a rotor, and a reluctance motor (a salient pole structure having a salient pole structure) that rotates by changing the magnetic resistance of the rotor depending on the rotor position. (Including motors that have a rotor, motors that change the magnetic resistance by providing air gaps in the rotor, and motors that change the magnetic resistance by combining permanent magnets). It is necessary to change the applied voltage, and the control device uses PAM (P
ulse Amplitude Modulation:
Pulse peak value control and PWM (Pulse Width)
Modulation (pulse width) control or the like is used.

When controlling a BL motor or a reluctance motor, it is necessary to synchronize the voltage phase according to the position of the rotor, and an advanced rotor position detector of several hundred pulses or more per rotation is used. In this case, a sine wave PWM control that approximates the applied voltage to a sine wave in synchronization with the detected phase is used. Normally, a rotor position detector is used as a magnetized detector for each phase, A sensorless system for detecting a rotor position by detecting an induced voltage of a motor is mainly used, and both a BL motor and a reluctance motor generally have a PWM control or a PAM control which is controlled by a rectangular wave.

When a rectangular wave voltage is applied, conventionally, a voltage called 180 ° energization shown in FIG.
° There were many voltages called energization. This is because when the three-phase motor is operated, if the above-described rotor magnetization detector is used, one pulse of the N-pole and the S-pole is obtained in one cycle corresponding to one cycle.
This is because each phase is detected at a phase angle of 120 °, and thus the pole positions in six modes can be determined per electric cycle.

However, both the 180 ° conduction and the 120 ° conduction have a disadvantage that vibrations due to the fifth and seventh harmonics are large, and vibration countermeasures are indispensable for blowers and the like that require a quiet sound.

[0006]

SUMMARY OF THE INVENTION As described above, the conventional 1
In an inverter device that performs a motor operation by applying a rectangular wave voltage called 80 ° conduction or 120 ° conduction,
Of the harmonic components inherent in the rectangular wave voltage, the fifth and seventh time harmonics that contribute the most to the vibration, the vibration and noise are large, and the low vibration and low noise are strongly required. ing.

The present invention applies a trapezoidal wave voltage or a pseudo sine wave voltage in which the rising and falling portions of the trapezoidal wave are sine waves to the motor, and the fifth and seventh order times which most contribute to the vibration. It is an object of the present invention to provide an inverter device that operates a motor with low vibration and low noise by reducing harmonics.

[0008]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention provides a method for generating a trapezoidal wave voltage or a time harmonic component of a pseudo sine wave voltage in which the rising and falling portions of the trapezoidal wave are sine waves. It is an object of the present invention to provide an inverter device which analyzes by a Fourier series and performs a motor operation with an optimum trapezoidal wave voltage waveform or an optimum pseudo sine wave voltage waveform.

As a result, it is possible to obtain an inverter device that operates the motor with low vibration and low noise.

[0010]

FIG. 1 is a voltage waveform diagram of the present embodiment. FIG. 1A shows a trapezoidal wave voltage waveform, and FIG. 1B shows a voltage waveform (hereinafter, abbreviated as a pseudo sine wave) in which the rising and falling portions of the trapezoidal wave are sine waves. In each waveform, a portion where the voltage changes to the right is referred to as a rising portion, and a portion where the voltage changes to the right is referred to as a falling portion.

As shown in FIG. 1A, a trapezoidal wave whose voltage changes upward from 0 ° to a phase angle A of a 180 ° trapezoidal wave or 180 ° trapezoidal wave as shown in FIG.
When a pseudo sine wave in which the voltage rises to the right from the 0 ° position of the pseudo sine wave to the phase angle A is obtained by Fourier series, these waveforms are symmetric and odd functions,
There is no s term, only a sin term, and if the harmonic order is n, then n is an odd number only (n = 1, 3, 5, 7,...). Then, one cycle is spatially set to 360 ° and 120 °.
The voltage applied to the three-phase connected motor with the phase shifted by 1
Since the operation is performed at a three-phase voltage (indicated as U-phase voltage, V-phase voltage, and W-phase voltage in FIG. 1) having a period of 360 ° and a phase difference of 120 °, a harmonic component of a third multiple is They cancel each other out and no longer exist. Therefore, the harmonic order n is 1, 5, 7, 11, 13,... The fifth and seventh harmonics are components that generate vibration six times the fundamental frequency. The larger the value, the greater the vibration (the stronger the excitation force).

In the trapezoidal wave and the pseudo sine wave shown in FIGS. 1A and 1B, when the phase angle A is 0 °, 180 °.
Becomes a rectangular wave energization, 1 (100%) the size of the fundamental wave component at the time of the magnitude 180 ° energization voltage of the n-th harmonic component of the square wave shown in FIG. 6 and the V _rectangular ratio ( If n), equation (1) is obtained.

[0013]

(Equation 1)

Further, the magnitude of the voltage of the n-th harmonic component of the trapezoidal wave, V _stand in a ratio to the size of 1 (100%) of the fundamental wave component at the time of the 180 ° energization and (n) Then, equation (2) is obtained.

[0015]

(Equation 2)

Similarly, the magnitude of the voltage of the n-th harmonic component of the pseudo sine wave is V _positive (n) at a ratio where the magnitude of the fundamental wave component at the time of 180 ° conduction is 1 (100%). Then, equation (3) is obtained.

[0017]

(Equation 3)

Here, when n = 1 in equation (3), equation (4) is obtained.

[0019]

(Equation 4)

If Equation (2) is expanded and one cycle of the trapezoidal wave voltage waveform is set to 360 °, in the case of the fifth and seventh harmonics which most contribute to vibration, the fifth harmonic component is If the phase angle A is 36 ° (180 ° / 5), the component becomes 0 (Equation (5)). Similarly, the seventh harmonic component has the phase angle A of 25.71 ° (180 ° / 7). ) Indicates that the component is 0. (Equation (6)). This component is 0
Means that when the motor rotates, the exciting force of the temporal harmonic is 0, and no vibration due to the temporal harmonic occurs.

[0021]

(Equation 5)

[0022]

(Equation 6)

Therefore, if the trapezoidal wave voltage waveform is expressed by the conduction angle width at the rising portion and the falling portion, the conduction angle width at the rising portion and the falling portion at which the fifth harmonic component is minimum is 36 ° × 2 = 72 °, and the energization angle width of the rising portion and the falling portion where the seventh harmonic component is minimum is 25.71 ° × 2 = 51.42 °.

Next, the equation (2) is developed, and the phase angle A is expressed as X
FIG. 2 shows the magnitude of each harmonic on the Y-axis.
From this, it can be seen that when the above-described phase angles are selected, the components of the fifth harmonic and the seventh harmonic are zero.

Further, in FIG. 2, the first harmonic component is called a fundamental wave component, which is a fundamental wave contributing to the rotation speed of the motor, and each harmonic component with respect to the fundamental wave becomes a vibration component. The value obtained by dividing the content by the fundamental wave means the distortion rate, and the smaller the value, the smaller the vibration. Here, the effective value of each harmonic component is squared, and the square root of the sum is the distortion component. The value obtained by dividing the distortion component by the effective value of the fundamental wave is the distortion factor. Is 73.64 ° at the phase angle A. However, when the phase angle A is 73.64 °, the component of the fundamental wave is reduced, and the voltage applied to the motor decreases at the basic rotation speed of the motor. Therefore, it is necessary to reduce the induced voltage constant of the motor. Since the motor current when the load torque is applied increases, the current capacity of the switching transistor increases, which is not a good idea. Therefore, the phase angle A at which the distortion factor becomes the minimum value is next to 73.64 °. Low distortion 3
FIG. 2 shows that the energization angle width of 5.19 ° and the rising part and the falling part is 35.19 ° × 2 = 70.38 °.
I understand more.

Further, if Equation (3) is expanded and one cycle of the pseudo sine wave voltage waveform is set to 360 °, the fifth harmonic and the seventh harmonic that contribute most to the vibration are the fifth harmonic. If the phase angle A is 37.76 °, the component of the wave component is 0 (Equation (7)). Similarly, if the phase angle A is 26.29 °, the component of the seventh harmonic component is 0. It turns out that it is. (Equation (8)). The fact that this component is 0 means that when the motor rotates, the exciting force of its temporal harmonic is 0, and vibration caused by the temporal harmonic does not occur.

[0027]

(Equation 7)

[0028]

(Equation 8)

Therefore, if expressed in terms of the conduction angle width of the rising portion and the falling portion of the pseudo sine wave voltage waveform, the conduction angle width of the rising portion and the falling portion where the fifth harmonic component is minimum is 37. 76 ° × 2 = 75.52 °, and the energization angle width of the rising portion and the falling portion where the seventh harmonic component is minimum is 26.29 ° × 2 = 52.
58 °.

Next, the equation (3) is developed, and the phase angle A is expressed as X
FIG. 3 shows the magnitude of each harmonic on the Y axis on the axis.
From this, it can be seen that when the above-described phase angles are selected, the components of the fifth harmonic and the seventh harmonic are zero.

Further, FIG. 3 shows that the minimum value of the distortion factor is 38.30 ° at the phase angle A and 38.30 ° × 2 = 76.60 ° at the conduction angle width of the rising portion and the falling portion. .

Note that when 180 ° is energized in the conventional example, the equation (1)
Is 0 °, the fifth harmonic component is 20% from the fundamental wave component according to the equation (9), and the equation (1)
From 0), the seventh harmonic component is 14.3%, which is 120%.
° When energized, the phase angle A in Equation (1) is set to 30 ° and Equation (1)
The absolute value of the fifth harmonic component is 17.3% from 1), and the absolute value of the seventh harmonic component is 12.4% from Expression (12). From the equations (13) and (14), the distortion factor for the fundamental wave is 24.times.
It turns out that it is 6%.

[0033]

(Equation 9)

[0034]

(Equation 10)

[0035]

[Equation 11]

[0036]

(Equation 12)

[0037]

(Equation 13)

[0038]

[Equation 14]

On the other hand, if the energization angle width of the rising portion and the falling portion of the trapezoidal wave voltage waveform is 72 °, the fifth harmonic component is 0 as described above, but the seventh harmonic component is similar. The calculated value is 3.1%, the distortion factor is 3.3%, and the conduction angle width at the rising portion and the falling portion is 5%.
If the angle is 1.42 °, the fifth harmonic component is 7.0%, the seventh harmonic component is 0, and the distortion factor is 7.2%. When the energization angle width of the rising portion and the falling portion at which the distortion rate due to the fifth harmonic and the seventh harmonic is the minimum value is 70.38 °, the fifth harmonic component is 0.5% and the fifth harmonic component is 0.5%. 7th harmonic component is 3.
0% and a distortion rate of 3.2%.

Further, if the energization angle width of the rising portion and the falling portion of the pseudo sine wave voltage waveform is 75.52 °,
As described above, the fifth harmonic component is 0, but the seventh harmonic component is 2.6% and the distortion factor is 2.8% by the same calculation, and the conduction angle width of the rising portion and the falling portion is calculated. Is 5
If the angle is 2.58 °, the fifth harmonic component is 6.9%, the seventh harmonic component is 0, and the distortion factor is 7.1%. When the energization angle width of the rising portion and the falling portion at which the distortion rate due to the fifth harmonic and the seventh harmonic is the minimum value is 76.60 °, the fifth harmonic component is 0.2% and the fifth harmonic component is 0.2%. The seventh harmonic component is 2.
6% and a distortion rate of 2.8%.

Even if the phase angle A of FIG. 1 is determined to be 36 ° (the conduction angle width of the rising portion and the falling portion is 72 °) in FIG. 1, the simultaneous ON of the switching transistors due to the time delay when the switching transistors are OFF is prevented. 2 and FIG. 3 show that the change of the angle of about several degrees does not significantly increase with the increase of the vibration.
The allowable angle of the phase angle A is 600
Assuming that 0 r / min (100 r / s) and the motor is magnetized with 8 poles, one cycle of the time wave is 2.5 ms, which prevents inconvenience of simultaneous ON of the switching transistors due to a time delay when the switching transistor is OFF. Since the dead time usually requires about 20 μS, the period of 20 μS is 3
If it is 60 °, it becomes 3 °, and the present application allows a variation of about 3 °.

As described above, when the trapezoidal wave voltage is applied to the motor, the energizing angle width of the rising portion and the falling portion is 72 °.
If the vibration component of the motor due to the fifth harmonic is 0, a low vibration waveform of 0 can be provided. If the vibration component of the motor due to the 7th harmonic is 0, a low vibration waveform of 0 can be provided.
If it is 0.38 °, a trapezoidal voltage waveform with minimal vibration due to both the fifth and seventh harmonic components can be provided.

When a pseudo sine wave voltage is applied to the motor, the energizing angles of the rising portion and the falling portion are set to 7 degrees.
5.52 ° provides a low-vibration waveform with zero motor vibration component due to the fifth harmonic, and 52.58 ° provides a low-vibration waveform with zero motor vibration component due to the seventh harmonic. If it is 76.60 °, it is possible to provide a pseudo sine wave voltage waveform with minimum vibration due to both the fifth and seventh harmonic components.

Note that the inverter device for the induction motor does not require the magnetization detector in the case of the above-described BL motor or reluctance motor, and performs open control without feedback from the sensor. The concept of the harmonic is the same, and the waveform of the present invention reduces the vibration due to the time harmonic.

Further, from FIG. 2, in the trapezoidal wave voltage waveform, the fifth harmonic component has a phase angle A of 72 °, and the seventh harmonic component has a phase angle A of 51.43 ° and 77.14 °. It becomes 0 at the time, and the seventh in the pseudo sine wave voltage waveform from FIG.
The higher harmonic component becomes 0 when the phase angle A is 52.96 °, and the effect of the vibration reduction is the same. However, the component of the fundamental wave is reduced, and the motor is applied at the basic rotation speed of the motor as described above. Since the voltage decreases, it is necessary to reduce the induced voltage constant of the motor. This is not advantageous because the current capacity of the switching transistor increases since the motor current increases when the same load torque is applied.

[0046]

As described above, when the three-phase motor is operated with the voltage waveform of the present invention, the vibration of the motor due to the time harmonic is reduced, and an inverter device for operating the motor with low vibration and low noise can be provided. .

[Brief description of the drawings]

FIG. 1A shows a voltage waveform diagram of the present embodiment. FIG. 1B shows a voltage waveform diagram of the present embodiment.

FIG. 2 is a diagram expressing the magnitude of the voltage of the in-phase angle and the harmonic component in a trapezoidal wave.

FIG. 3 is a diagram showing the magnitude of the voltage of the in-phase angle and the harmonic component in a pseudo sine wave.

FIG. 4 is a voltage waveform diagram of a conventional example with 180 ° conduction.

FIG. 5 is a voltage waveform diagram of a conventional example with 120 ° conduction.

FIG. 6 is a square wave voltage waveform diagram.

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Claims (12)

[Claims] 1. An inverter device for operating a BL motor or a reluctance motor with a trapezoidal wave, wherein the energizing angle width of the rising portion and the falling portion of the trapezoidal wave is 72.
° ± 3 ° inverter device. 2. An inverter device for operating a BL motor or a reluctance motor with a trapezoidal wave, wherein the energization angle width of the rising and falling portions of the trapezoidal wave is 51.
° ± 3 ° inverter device. 3. An inverter device for operating a BL motor or a reluctance motor with a trapezoidal wave, wherein the energization angle width of the rising and falling portions of the trapezoidal wave is 70.
° ± 3 ° inverter device. 4. An inverter device for operating an induction motor with a trapezoidal wave, wherein a conduction angle width of a rising portion and a falling portion of the trapezoidal wave is 72 ° ± 3 °. 5. An inverter device for operating an induction motor with a trapezoidal wave, wherein a conduction angle width of a rising portion and a falling portion of the trapezoidal wave is 51 ° ± 3 °. 6. An inverter device for operating an induction motor with a trapezoidal wave, wherein a conduction angle width of a rising portion and a falling portion of the trapezoidal wave is 70 ° ± 3 °. 7. An inverter device for operating a BL motor or a reluctance motor, wherein a rising part and a falling part of a trapezoidal wave are driven by a pseudo sine wave that is a sine wave, and a rising part and a falling part of the pseudo sine wave are used. An inverter device having a power distribution angle width of 76 ° ± 3 °. 8. An inverter device for operating a BL motor or a reluctance motor, wherein a rising portion and a falling portion of a trapezoidal wave are driven by a pseudo sine wave that is a sine wave, and a rising portion and a falling portion of the pseudo sine wave are used. An inverter device in which the energization angle width is 53 ° ± 3 °. 9. An inverter device for operating a BL motor or a reluctance motor, wherein a rising portion and a falling portion of a trapezoidal wave are driven by a pseudo sine wave, which is a sine wave, and a rising portion and a falling portion of the pseudo sine wave. Inverter device whose energization angle width is 77 ° ± 3 °. 10. An inverter device for operating an induction motor, wherein a rising portion and a falling portion of a trapezoidal wave are driven by a pseudo sine wave that is a sine wave, and a conduction angle width of a rising portion and a falling portion of the pseudo sine wave. Is 76 ° ± 3
° is an inverter device. 11. An inverter device for operating an induction motor, wherein a rising portion and a falling portion of a trapezoidal wave are driven by a pseudo sine wave which is a sine wave, and a conduction angle width of a rising portion and a falling portion of the pseudo sine wave. Is 53 ° ± 3
° is an inverter device. 12. An inverter device for operating an induction motor, wherein a rising portion and a falling portion of a trapezoidal wave are driven by a pseudo sine wave that is a sine wave, and a conduction angle width of a rising portion and a falling portion of the pseudo sine wave. Is 77 ° ± 3
° is an inverter device.