JPH09205765A - Input filter of general purpose inverter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To downsize an input filter by constituting a ripple removal filter and an EMI (radio noise) filter as one filter. SOLUTION: The reactors L3 and L4 of a ripple removal filter and the rectors L1 and L2 of an EMI filter are constituted as one reactor ACL which has a plurality of taps 2 and 5, and a resonance circuit 9 consisting of C, L, and R is connected to the tap 5 so as to have a ripple removal filter function, and the capacitors C1 , C2 , and C2 ' are connected to the input terminal 1 and the tap 2 so as to have an EMI filter function. As compared with the case that the ripple removal filter and the EMI filter are constituted separately, the size of the input filter part becomes smaller, and the number of parts decreases, so the cost is reduced, and the improvement of reliability can be expected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an input filter for a general-purpose inverter used as a variable speed device for general industry.

[0002]

2. Description of the Related Art Generally, an input filter of a general-purpose inverter is used by being inserted between a power supply and an inverter for the purpose of preventing malfunction of other electric / electronic devices connected to the same power supply system. As shown in FIG. 3, the input filter includes reactors L ₁ and L ₂ , capacitors C ₁ , C ₂ and C ₂ ′.
It is composed of such a characteristic number 100kH _Z ~ Number 10
It is general that are designed to have a large damping effect in a frequency band region of 100 MHz _Z-order.

On the other hand, due to the regulation of power supply high frequency in Japan and abroad in recent years, the rectifier circuit of a general-purpose inverter must be replaced with a switching control type by a converter in order to control the power supply current to a sine wave from the conventional simple capacitor input type. The situation is becoming obligatory. In this case, the converter because the switching element such as IGBT, is applied general, the switching frequency is selected to approximately several kH _Z ~20kH _Z. Was but connexion, converter when the control was performed in several kH _Z ~ to the power supply current
Ripple current 20 kHz _Z is superimposed. In order to remove this ripple current, as shown in FIG. 4, reactors L ₃ and L ₄
When, C, L, consisting of the resonant circuit 9 consisting of R 10KH _Z
A filter F ₂ having an attenuation effect in the front and rear frequency bands is inserted.

When it is attempted to simultaneously take measures against noise of a general-purpose inverter and measures against power source harmonics by a converter, as shown in FIG. 5, the cutoff frequency is high (MH).
Two types are required: a radio noise (EMI) filter 1 in the _Z ) region and a ripple removal filter 2 near the switching frequency of the converter.

[0005]

As described above, when the noise countermeasure of the general-purpose inverter and the power source harmonic countermeasure by the converter are to be simultaneously implemented, two kinds of filters F _{1 having} different frequency bands to be attenuated are used. , F ₂ are inserted in series between the power source e and the input side of the inverter INV. Therefore, a general-purpose inverter, which is required to be small and low in cost, is extremely disadvantageous from the viewpoint of the whole system.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to reduce the number of parts capable of simultaneously implementing noise countermeasures and power supply harmonics countermeasures and improving reliability. However, it is another object of the present invention to provide a general-purpose inverter input filter that is compact and can reduce costs.

[0007]

An input filter of a general-purpose inverter according to the present invention comprises a reactor having a plurality of intermediate taps to form a filter for removing current ripple caused by switching of a converter section, and the intermediate taps. Is used to provide an EMI filter function for preventing malfunction of peripheral devices, and one input filter is provided with a ripple removal filter function and an EMI filter function.

[0008]

1 is a circuit diagram of an input filter (for one phase) of a general-purpose inverter having an EMI filter function and a ripple removal filter function, and FIG. 2 is a block diagram of a harmonic countermeasure inverter system.

In FIG. 1, ACL is an input filter reactor having terminals 1 and 6 and intermediate taps 2 and 5,
The intermediate tap 2 is provided from the terminal 1 at a position corresponding to the reactor L ₁ of the conventional EMI filter F ₁ (FIG. 3), and the intermediate tap 5 is provided from the terminal 6 to the conventional ripple removal filter F ₂ described above.
It is provided at a position corresponding to the reactor L ₄ in (Fig. 4),
Intermediate tap 2 and 5 reactors of the EMI filter F ₁ between L ₂ and the ripple removing filter F ₂ reactor L ₃
The reactor (L ₂ + L ₃ ) equivalent to the sum of is formed.

EM is applied to the terminal 1 and the intermediate tap 2.
Similar to the I filter F ₁ , the input terminal 1 is connected with the interphase capacitor C ₁ , the intermediate tap ₂ is connected with the capacitor C ₂ ′ and the interphase capacitor C ₂ , and the intermediate tap 5 is connected with the ripple removal filter F ₂ . , C, L, and R are connected to the resonance circuit 9.

As described above, the input filter of the present invention is
The reactors L ₁ and L ₂ of the conventional EMI filter and the reactors L ₃ and L ₄ of the ripple removal filter F ₂ are configured as one reactor ACL, and from the input terminal 1 side to the position corresponding to the reactor L ₁ and from the output terminal 6 side. Reactor L ₄
The taps 2 and 5 are provided at the position corresponding to the input terminal 1
A capacitor C ₁ , C ₂ , C ₂ ′ is connected to the tap ₂ like the conventional EMI filter F ₁ , and a circuit including a capacitor C ₅ , a resistor R ₃ and a reactor L ₅ is connected to the tap 4 like the ripple removing filter F _2. Since they are connected, they have the function of the EMI filter F _{1 and} the function of the ripple removal filter F ₂ .

Since the reactors L _{1 to} L ₄ are configured as one reactor ACL, the number of parts of the input filter can be reduced and the size can be reduced. Therefore, a general-purpose inverter system with a power supply harmonic countermeasure function by a converter can be downsized. Can be realized.

[0013]

Since the present invention is configured as described above, the following effects can be obtained.

(1) By using an AC reactor having a plurality of intermediate taps as a ripple removal filter as a countermeasure against power source harmonics, the ripple removal filter also has an EMI filter function by utilizing the intermediate taps. You can

(2) When this input filter is applied to the power supply harmonics countermeasure of a general-purpose inverter, the size of the input filter can be reduced as compared with the conventional system using the ripple removal filter and the EMI filter. The size of the system can be reduced. Moreover, since the number of parts of the input filter unit is reduced, cost reduction and reliability improvement can be expected.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing one phase of an input filter example according to the present invention.

FIG. 2 is a block diagram of a harmonic countermeasure system for a general-purpose inverter according to the present invention.

3A and 3B are a circuit diagram and a frequency characteristic diagram showing an example of a conventional EMI filter.

4A and 4B are a circuit diagram and a frequency characteristic diagram showing an example of a conventional ripple removal filter.

FIG. 5 is a block diagram of a harmonic countermeasure system for a conventional general-purpose inverter.

[Explanation of symbols]

F ... EMI filter + ripple removing filter F ₁ ... EMI filter F ₂ ... ripple elimination filter INV ... converter by the power supply harmonic countermeasure function with inverter ACL ... for more with intermediate tap input filter (AC) reactor e ... Power M ... motor

Claims (1)

[Claims] 1. A reactor having a plurality of intermediate taps is used to form a filter for removing current ripple caused by switching of a converter section, and the intermediate taps are used to prevent malfunction of peripheral devices. An input filter for a general-purpose inverter, characterized in that one input filter has a ripple removal filter function and an EMI filter function.