KR100525315B1 - Waveform correction filters - Google Patents

Abstract

The present invention relates to a waveform correction filter, wherein the waveform correction filter absorbs several types of power pollution, including high frequency spikes, surges and other forms of high frequency oscillations caused by switching on and off inductive loads. And connected to an AC power line for removal. The waveform correction filter of the present invention includes a coaxial amorphous troidal inductor and a fuse connected between a power line and a neutral line, and a low pass filter connected in series with the fuse and the coaxial amorphous toroidal inductor. Has The filter includes a capacitor, a varistor connected in parallel with the capacitor, and a magnetic core inductor connected in series with the capacitor and the varistor. The lamp may be connected in series with the resistor and the magnetic core inductor or across the resistor. Single or three phase wires or delta circuits allow for multiple placements where multiple waveform correction filters are connected.

Description

Waveform Correction Filter {WAVEFORM CORRECTION FILTERS}

For many years, the person monitoring the use of significant amounts of alternating current power has been involved in the quality of this power. Most of the new devices in use are sensitive to transient voltages such as spikes, power surges, and random radio frequency (r.f.) noise, but at the same time, these devices can generate their own transient voltages that are returned to power lines. When the switch is turned off and on, reflective impulses are generated in the line. The motors that drive and stop generate power impulses known as surges.

In addition to the effects of random radio frequencies, various kinds of electrical machines can generate harmonic frequencies. All power pollution of this kind reduces the efficiency of electric motors, generators and transformers in particular. The waveform of the power supplied to such a device is distorted, causing eddy currents to occur in the iron-containing metal parts of the device, such as the transformer core and the motor stator and rotor. The eddy currents in the motors consume power in the form of heat, for example, allowing more power to do the same. Motors can be damaged by the effects of excessive heat or by problems in insulation, causing them to fail long before their expected service life.

While much effort has been made to improve the quality of power supplied to various consumers, there is little awareness of power pollution occurring within a single device as a result of the operation of a significant number of electric motors, switches, computers and other power consuming devices. I can't.

In essence, when the inductive load is switched off, very high voltage reflections, many times larger than the standard maximum of the applied voltage, are returned to the power line. A typical transient voltage is shown superimposed on a sine wave as shown in FIG. The average industrial or commercial circuit receives many transients in excess of 1000 volts each day. This transient voltage reflects and triggers other vibrations in the network. These reflections are bounced back and forth until they are absorbed or damaged in the system.

Another fault occurs when the load is unbalanced in a three-phase line, causing an unwanted phase difference between voltage and current. High harmonic neutral currents flow and react with transients and surges on the line.

As noted above, it should be noted that internal power pollution within the network can often be a far more serious factor in the efficiency of motors and the like than irregularities in power supplied from outside the device.

It is estimated that up to 60% of all electricity, now or in the near future, will flow through nonlinear loads. This load is a major source of power pollution.

If a predetermined means can be provided which are connected to the individual power lines and capable of absorbing or eliminating the transient voltages, significant effective gain can be obtained and can prevent the transient voltages from being returned to the power lines.

It is therefore an object of the present invention to provide a waveform correction filter which removes and absorbs random radio frequency noise, spikes, surges and harmonics from the alternating current power provided to the power consumption unit described above.

It is another object of the present invention to provide a bidirectional waveform correction filter in which all components are bidirectional.

Another feature of the present invention is to provide a waveform correction filter that substantially reduces the maintenance cost for the associated device.

Other objects and advantages of the invention will be apparent from the following description taken in conjunction with the drawings.

The invention will be more clearly understood with reference to the following description and attached drawings.

The waveform correction filter system of the present invention operates in the following manner. The system is connected to a line (typically from a line to a neutral line) as shown in FIG. 2 and only works if there is a possibility that there are disturbances. The unit performs three important functions:

1. The unit senses a rising transient voltage and clips and absorbs all energy above 10% above the peak value of the voltage. Ie 120 V rms. +/- 190V for line.

2. This slows down the rise time of the transient voltage, so that the rise transient voltage "glides" to the clipping level. This is done so that clipping does not indicate another switching event, thereby causing further ringing.

3. It filters and absorbs all high-ringing disturbances at a rate of 6 db per decade over 60 Hz.

This behavior is illustrated below:

FIG. 2 shows a typical line connected to a neutral line in the waveform correction filter of the present invention.

The items of the components in the figure are as follows:

10 fuses, protective line type

12 inductor, coaxial amorphous toroid made of soft magnetic material

13 Varistors, Metal Oxides

14 Capacitors, polypropylene ac rated

15 Magnetic Core, Nanocrystalline Torodial

16 resistors, limited to carbon

17 lamps, neon

The operation of the circuit proceeds as follows:

As the transient voltage shown in FIG. 1 generally begins to rise at intervals of one microsecond, the rise time may initially be slow or long to a predetermined magnitude selectable by the inductor 12, and about It is clamped by the varistor 13 at twice the rms line voltage. For a 120 V rms line, this would be about 190 V. The level depends on the surge current and the line impedance at the moment of the transient voltage rise. Before the transient occurs, the varistor 13 has an infinitely high resistance in the circuit. However, at the moment of clipping, the varistor 13 has a very low impedance and at the same time serves as a current generator. Since the voltage across capacitor 14 does not change instantaneously during switching of varistor 13, capacitor 14 becomes a virtual short circuit and provides a path through which high current can flow. The capacitor 14 then begins to charge. Now, the components shown in FIG. 2, the magnetic core 15, the resistor 16 and the lamp 17, are connected across the capacitor 14. The varistor 13 is switched back to high impedance, and the capacitor 14 transmits its energy to the components 15, 16, 17. The energy can be calculated by the formula:

E (joules) = V (clamping voltage) × I (surge current) × time

For example, using Siemens' S20K130 varistor, the maximum energy capacity is 44J and clamped between 185 and 225V.

The magnetic core 15 is a soft magnetic element having a relatively very high initial permeability (μ = 30,000), extremely low loss, and high saturation magnetic flux density (B _sat = 1.2 tesla). This means that the core can be magnetized very easily and maintains this condition through wide flux transmission. Thus, the energy applied to the capacitor is transferred to the "reservoir" of the high magnetic core. The energy is then transferred to the equivalent resistance of the resistor 16 and the lamp 17, where the energy is collected and absorbed for a longer time interval.

The network also functions as a low pass filter in addition to absorbing disturbance energy.

The following describes the details of the low pass filter network.

The voltage clamping device, referred to as VARISTOR 13, is simply indicated as "MOV" 13. This MOV 13 is a component having a variable impedance that depends on the current flowing through the device or the voltage across the device. Nonlinear impedance characteristics are shown and Ohm's law applies, but the equation has a variable R. The change in impedance is monotonous but does not include discontinuities.

The circuit is inherently unaffected by the presence of the MOV 13 before and after the presence of an over-voltage transient for any steady state voltage below the aforementioned clamping level. Voltage clamping operation results from an increase in current generated through the device as the voltage rises. If this current increase is greater than the voltage rise, the impedance is nonlinear.

The apparent "clamping" of the voltage results from increased voltage drop (IR) in the source impedance due to increased current. The device depends on the source impedance to provide clamping. This operation is described as a voltage divider, as shown in FIG.

The ratio of the divider is not constant and varies. If the source impedance is very low, the ratio is low. The MOV 13 cannot be valid when the source impedance is close to zero and functions best when the voltage divider operation can be realized.

If the MOV is the only component responsible for eliminating the transient overvoltage, it can easily be seen that additional ringing transients occur due to its nonlinear switching process.

The resulting ringing frequency components are several times greater than the power line frequency of the AC circuit as well as the DC circuit.

Thus, the obvious solution is to integrate a low pass filter between the source of the transient voltage and the sensitive load.

The simplest form of filter is a capacitor located across the line. The reactive impedance of the capacitor uses the source impedance to form a voltage divider, which causes attenuation of the transient at high frequencies.

This simple method can produce undesirable side effects such as:

1. Undesirable resonance of an inductive component located elsewhere in the circuit that induces a high peak voltage.

2. high inrush current during switching, or

3. Excessive reactive load in the power system voltage.

This unwanted effect can be reduced by adding a series resistor. However, the disadvantage of the added resistance is that it lowers the effective clamping result.

In order to achieve the most successful clamping, attenuation, and absorption of transient voltage energy, a highly transmissive magnetic core is integrated with the aforementioned capacitor and attenuation resistor.

By second-order tuning, a critically damped RLC low pass filter can be created. Thus, the unwanted effects mentioned above can be eliminated. However, no inductance will function satisfactorily. Particularly required for such a magnetic core (MAGNETIC CORE) 15, hereafter referred to as "L" is as follows:

1) Since the capacitor response is nonlinear with frequency but linear with current, L's response with respect to current and frequency should be linear. This response condition is shown in the hysteresis graph of magnetic flux density (B) vs. magnetization force (H) of FIG. 4.

2) Also, since the impinging oscillating wave is not balanced as a pure sine wave that does not have a DC component statistically, it is necessary for the core to be reset during each period of the ringing frequency. This condition is satisfied as shown in the graph, where it can be seen that not only coercivity but also residual magnetism B _r becomes almost zero.

3) In order to function at its predetermined level throughout all components of the colliding ringing wave derived from this transient, L must remain stable with respect to frequencies in the range of 1 MHz and above. This condition is met by the incorporation of certain magnetic materials used in the waveform correction filter of the present invention.

4) The pulse permeability versus magnetic flux density change of the magnetic core L should remain within a certain range as shown in the graph of FIG.

Under somewhat arbitrary driving from the source, the range of permeability described above is important because the inductance value must be maintained at its predetermined level.

The network essentially forms a series RLC circuit as shown in FIG.

The homogeneous equation valid for this system is given by:

Where d / dt = s. Now

to be.

Critical resistance is determined as follows:

And the corresponding damping ratio is

to be.

Natural frequency,

Given by to be.

The characteristic equation is now

Becomes

When implementing the special properties of nanocrystalline core materials, two important parameters of the characteristic equation, ξ and ω _n dominate the performance of the filter system. Performance is centered on current channeling and tuning, both based on cutoff frequency characteristics and proper damping.

The damping ratio ξ is chosen such that the impinging ringing transient is processed and absorbed by the dissipating R of the circuit (shown in Figure 2), and the final frequency ω _n is rolled at -40 dB per 10 units. Roll-off is determined to provide sufficient attenuation at the higher frequencies required in a particular system.

The combination of core material and circuit arrangement is key to the filter operation as described above.

7 is a schematic diagram showing the first and second filter networks 22 of the present invention connected in a single-phase line. Any three-phase rod, such as a three-phase motor, may be connected to the circuit of FIG. 7 at the upper left side connected to lines 40, 42, 44 and at the terminals shown in FIG. The waveform correction circuit of FIG. 7 is connected to an AC power supply via lines 19 and 20. The first and second filter network 22 are connected between the line 19 and the neutral line 21 and between the line 20 and the neutral line 21, respectively. A separate ground line 23 is connected between the motor housing and earth ground.

Each filter network 22 includes a fuse 10, a coaxial amorphous toroidal inductor 12 of soft magnetic material applied in series to the fuse, and the coaxial inductor 12. And a capacitor 14 connected between and the neutral line 21. The MOV 26 is connected in parallel with the capacitor 14, and the series circuit of the resistor 30 with the winding with the magnetic core 28 is also connected in parallel with the capacitor 14. The lamp 32 is connected in parallel with the resistor 30. The ground line 23 is connected between the case of the motor 18 and an equivalent of ground or ground.

8 is a schematic diagram showing first, second, and third filter networks 22 connected to a three-phase Y-type network to a three-phase load, each filter network 22 having a phase line 40, 42. Is connected between one of the lines 44 and the neutral line 46. As in FIG. 1, a separate ground line 48 is connected between the case of the three-phase rod and the ground. Each filter network 22 is identical to the filter of FIG. 7 except that the values of the components will vary depending on the applied voltage and the like.

9 is a schematic diagram showing first, second, and third filter networks 52 connected to a three-phase Δ-type network to a three-phase motor 50. In this case, the first, second, and third filter networks 52 are connected between the phase lines 54, 56, 58. Each filter network 52 is essentially with the filter network 22 except that the resistor 30, the lamp 32, and the magnetic core and the winding 28 are all connected in series across the capacitor 24. similar. This variant is a matter of design choice depending on the desired effective resistance. A separate ground line 60 is connected between the case of the motor 50 and the ground.

The embodiments of the present invention described above are merely illustrative of the principles of the present invention and are not to be considered as a limitation of the present invention. Instead, the scope of the present invention will be determined by the following claims and their equivalents.

According to the present invention, there is provided a waveform correction filter which removes random radio frequency noise, spikes, surges and harmonics from the AC power provided in the above-described power consumption unit, which is suitable for the purpose of the present invention.

1 is a graph illustrating distortion of a sine wave due to a high frequency transient voltage.

2 is a schematic diagram of a basic waveform correction filter system.

3 is a schematic diagram of a voltage divider showing the characteristics of a transient voltage suppression system.

4 is a graph showing a typical B-H curve having characteristics of a magnetic core in the system of the present invention.

5 is a graph showing the magnetic flux density versus pulse permeability of the magnetic material of the magnetic core in the system of the present invention.

6 is a diagram of a simplified equivalent RLC circuit illustrating the characteristics of the transient voltage suppression system.

7 shows a waveform correction filter system of the present invention coupled to a single phase motor.

8 shows a waveform correction filter system of the present invention coupled to a three phase Y-type circuit.

Figure 9 shows a waveform correction filter system of the present invention coupled to a three phase Δ type circuit.

* Description of the symbols for the main parts of the drawings *

10: fuse, protective line type

12: inductor, coaxial amorphous toroid made of soft magnetic material

13: varistor, metal oxide

14: capacitors, polypropylene ac rated

15: magnetic core, nanocrystalline toroid

16: Resistor, limited to carbon

17: lamp, neon

Claims (20)

Waveform correction filter connected to AC power, fuse; Inductance means connected in series with said fuse; And A filtering network connected in series with said fuse and said inductance means, said filtering network comprising a capacitor, a varistor connected in parallel with said capacitor, and a magnetic core inductor and resistance means connected in series with each other in series with said capacitor and said varistor. Correction filter. Waveform correction filter connected to AC power, fuse; A coaxial amorphous toroidal inductor of soft magnetic material connected in series with the fuse; And And a filtering network connected in series with the fuse and the coaxial amorphous toroidal inductor, wherein the filtering network comprises a capacitor, a varistor connected in parallel with the capacitor, and a magnetic core inductor and a resistor connected in series with the capacitor and the varistor in series. Waveform correction filter included. The waveform correction filter of claim 2, further comprising a lamp connected in parallel with the resistor. 3. The waveform correction filter of claim 2, further comprising a lamp connected in series with the magnetic core inductor and the resistor. 3. The waveform correction filter of claim 2, wherein the magnetic core inductor has high initial permeability, low loss, and high saturation magnetic flux density. 3. The waveform correction filter of claim 2, wherein the filtering network comprises a low pass filter that is critically damped. 3. The waveform correction filter of claim 2, wherein the response of the magnetic core inductor is substantially linear with respect to current and frequency. 3. The waveform correction filter of claim 2, wherein the remanence of the magnetic core reactor is approximately zero. A waveform correction filter network system that includes two power lines and a neutral line and is connected to an AC power source. A first filter network connected between one of the power lines and the neutral line and a second filter network connected between the neutral line and the other of the power lines, Each of the first and second filter networks comprises a coaxial amorphous toroidal inductor of soft magnetic material connected to one of the power lines and a low pass filter connected in series with the coaxial amorphous toroidal inductor, the low pass filter comprising a capacitor, A waveform correction filter network system in which a varistor and an inductance member having a magnetic core inductor and a resistor in series with each other are connected in parallel. 10. The waveform correction filter network system of claim 9, further comprising a ramp connected in parallel with each resistor. A waveform correction filter network system to be connected to an AC power source. A first filter network connected between one terminal of the power source and the neutral line and a second filter network connected between the other terminal of the power source and the neutral line, Each of the first and second filter networks has a fuse, a coaxial amorphous toroidal inductor of soft magnetic material connected in series with the fuse, and a filter connected in series with the coaxial amorphous toroidal inductor, the filter in parallel with the capacitor, the capacitor. A waveform correction filter network system having a connected varistor and a magnetic core inductor and a resistor in parallel with the capacitor and the varistor and in series with each other. 12. The waveform correction filter network system of claim 11, wherein the magnetic core inductor has high initial permeability, low loss and high saturation magnetic flux density. 12. The waveform correction filter network system of claim 11, wherein the residual magnetic field of the magnetic core reactor is approximately zero. 12. The waveform correction filter network system of claim 11, further comprising a ramp connected in parallel with each resistor. A waveform correction filter network system connected between a three-phase Y-type AC power supply with a three-phase line and a neutral line, A first, second, and third filter network, wherein each filter network is connected between one of the three phase lines and the neutral line, wherein each filter network is connected to one of the three phase lines. A coaxial amorphous toroidal inductor and a filter in series with the coaxial amorphous toroidal inductor, the filter comprising a capacitor, a varistor connected in parallel with the capacitor, and a magnetic core inductor and a resistor in parallel with and connected in series with the capacitor and the resistor. Waveform correction filter network system. 16. The waveform correction filter network system of claim 15, further comprising a fuse coupled between each of the three phase lines and the coaxial amorphous inductor. 16. The waveform correction filter network system of claim 15, wherein the magnetic core inductor has high initial permeability, low loss and high saturation magnetic flux density. A waveform correction filter system connected to a three-phase Δ AC power source with a three-phase line, A first, second, and third filter network, the first filter network being connected between a first phase line and a second phase line, the second filter being the second phase line and the third phase line. The third filter network is connected between the third phase line and the first phase line, The suppression network each includes a coaxial amorphous toroidal inductor of soft magnetic material connected to one of the three phase lines and a filter connected in series with the coaxial amorphous toroidal inductor, the filter comprising a capacitor, a varistor connected in parallel with the capacitor and the 10. A waveform correction filter system having a capacitor and a magnetic core inductive member in parallel with and in series with the resistor. 19. The waveform correction filter system of claim 18, further comprising a fuse coupled between each of the three phase lines and the coaxial amorphous toroidal inductor. 19. The waveform correction filter system of claim 18, further comprising a lamp connected in series with each of the resistors and the inductive member.