JP2004159376A - Waveform shaping filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To absorb and remove electric power pollution such as high-frequency spikes and surges caused by the switching of an inductive load or the like. <P>SOLUTION: Respective waveform shaping filters are connected between three-phase power lines 40 to 44 and a neutral line 46, and a fuse and a coaxial amorphous toroidal inductor are connected to a low-pass filter 22 in series. The filter includes a capacitor, a varistor connected to the capacitor in parallel, and a magnetic core inductor which is connected to the capacitor and the varistor in parallel and is connected to each other in series. A lamp may be connected to a resistor and a magnetic core inductor in series. In the case of delta three-phase AC connection, respective waveform shaping filter is disposed in a phase line. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
For many years, those tasked with monitoring the use of large amounts of AC power have been concerned with the quality of such power. Many of the newer devices currently in use are susceptible to transients such as spikes, power surges and random radio frequency (RF) noise, while at the same time such devices generate their own transients. As a result, the transient voltage is superimposed on the power line. When the switch turns off and on, a reflected impulse is created on the line. When the motor starts and stops, a power impulse known as a surge is triggered.
[0002]
Various types of motors generate harmonics in addition to random RF contamination. These types of power pollution reduce the efficiency, especially of electric motors, generators and transformers. The waveform of the power supplied to these devices is distorted, thereby creating eddy currents in the ferrous metal components in the devices, such as the transformer core and the stator and rotor of the motor. As a result, eddy currents in the motor, for example, to perform the same task, waste power as heat and cause more power consumption. A motor will fail either from the effects of excessive heat or damage to the insulation, causing it to fail long before its expected service life.
Much has been done to improve the quality of power delivered to various consumers, but as a result of operating many of the electric motors, switches, computers, and other power consuming devices, a single There was little recognition that power pollution would occur in the device.
[0003]
Basically, whenever an inductive load is switched, voltage reflection ringing on the power line, many times much higher than the normal peak value, flows. FIG. 1 shows a typical transient voltage superimposed on a sine wave. The average industrial or commercial network receives many transients daily, in excess of 1000 volts. These transients reflect and cause other oscillations in the network. These echoes bounce back and forth until they are absorbed or damaged in the system.
When the load is unbalanced in a three-phase line, other disturbances occur that cause an undesirable phase difference between voltage and current. Harmonic neutral current flows on the line in response to transients and surges.
[0004]
From the foregoing, it can be seen that internal power pollution in the network is a much more serious factor in terms of efficiency, such as motors, than mismatch of power supplied from outside the device. .
It is estimated that up to 60 percent of all power is and will continue to flow in non-linear loads. It is these loads that are the main source of power pollution.
Connected to individual power lines leading to such power consumers, such transients can be absorbed or otherwise removed, thereby preventing the transients from being superimposed on the power lines. If measures could be provided to prevent this, it would be possible to obtain significant efficiency gains.
[0005]
Accordingly, an object of the present invention is to provide a waveform shaping filter that removes and absorbs random RF noise, spikes, surges, and harmonics from the AC power applied to the above-described power consumption device.
It is another object of the present invention to provide a bidirectional waveform shaping filter by making all components bidirectional.
Another object of the present invention is to provide a waveform shaping filter that can reduce the maintenance cost for the related device.
Other objects and advantages of the present invention will become apparent from a consideration of the following detailed description taken in conjunction with the drawings.
[0006]
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The waveform shaping filter of the present invention functions in the following manner. The filter is connected to a line as shown in FIG. 2 (typically a line leading to neutral) and only works when a fault is present. The filter device performs three important functions. 1. Detects increasing transients and clips and absorbs any energy that exceeds 10% of the voltage peak. That is, for example, for a power supply having an effective value of 120 volts, the voltage is ± 190 volts.
2. The rise time of the transient voltage is delayed so that the rising transient voltage "gradually transitions" to the clipping level. This is done so that clipping does not cause another switching event and cause further ringing.
Above 3.60 Hz, all high ringing faults are filtered and absorbed at a rate of 6 dB per 10 Hz.
These effects are illustrated in FIG.
[0007]
FIG. 2 is a typical diagram in which the waveform shaping filter of the present invention is connected to a neutral line.
The component items in this circuit diagram are functionally represented as follows.
10 Line protection type fuse 12 Soft magnetic coaxial amorphous toroidal inductor (inductor)
13 Metal oxide varistor 14 Polypropylene AC rated capacitor 15 Nanocrystalline toroidal (ring) type magnetic core 16 Carbon type damping resistor 17 Neon lamp
The circuit operation is as follows.
When the transient voltage shown in FIG. 1 rises, its rise time is delayed or extended by an inductor 12 by a predetermined selectable amount, typically for one microsecond, and the varistor 13 causes the rms line voltage to rise. √2 is clamped. For a power supply with an effective value of 120 volts, this would be approximately 190 volts. This level depends on the surge current and the line impedance at the moment of the rise of the transient voltage. The varistor 13 appears as an infinitely high resistance in the circuit before the transient voltage occurs. However, at the time of clipping, the varistor has a very low impedance and simultaneously conducts current. Since the voltage across the capacitor 14 cannot instantaneously change when the varistor 13 is switched, the capacitor 14 virtually forms a short circuit, and provides a path for a high current to flow. Thus, charging of the capacitor 14 is started. The magnetic core 15, the resistor 16, and the lamp 17, which are the elements shown in FIG. The varistor 13 switches back to high impedance and the capacitor 14 transfers its energy to the components 15, 16 and 17. This energy is
E (joule)
= V (clamping voltage) × I (surge current) × time. For example, if a Siemens S20K130 varistor is used, its maximum energy capacity is 44 Joules and clamps 185-225 volts.
[0009]
The magnetic core 15 is a soft magnetic element having a very high initial magnetic permeability (u = 30,000), a very low loss, and a high saturation magnetic flux density (Bsat = 1.2 Tesla). This means that the core is magnetized very easily and maintains this state over a wide flux penetration. Thus, the energy applied to the capacitor is now transferred to the "reservoir" of the high magnetic core. This energy is then processed into the equivalent resistance of resistor 16 and lamp 17, where energy is collected and absorbed over a longer time span.
This network effectively functions as a low-pass filter in addition to absorbing disturbance energy.
[0010]
It is important to consider the details of the low pass filter network.
The voltage clamping device is referred to as a varistor 13, but will be simply referred to as “MOV” 13 hereinafter. The MOV 13 is a component having a variable impedance that changes depending on the current passing through the device or the voltage across its terminals. Non-linear impedance characteristics are shown and Ohm's law applies, but the equation has a variable R. The change in impedance is monotonic and does not include discontinuities.
[0011]
As described earlier, due to the presence of MOV 13, this circuit is essentially unaffected before and after the appearance of an overvoltage transient for any constant voltage below the clamping level. Voltage clamping effects occur as a result of the increased current being drawn through the device as the voltage increases. If this current increase is greater than the voltage increase, the impedance is non-linear.
Obvious "clamping" of the voltage occurs as a result of the increased voltage drop (IR) of the source impedance due to the increased current. The device provides clamping, depending on the source impedance. As shown in FIG. 3, this effect can be represented as a voltage divider.
[0012]
The ratio of the voltage divider is not constant but varies. If the source impedance is very low, the voltage division ratio is low. The MOV 13 cannot exhibit cure at power supply impedances close to zero, but works best when partial pressure action is feasible.
It will be readily appreciated that if the MOV is the only component that serves to eliminate overvoltage transients, then its non-linear switching behavior may create additional ringing transients. Would.
The resulting ringing frequency component of the transient voltage is several times the frequency of the power supply lines of the AC and DC circuits.
Thus, an obvious solution is to incorporate a low pass filter between the source of the transient voltage and the delicate load.
[0013]
The simplest form of filter is a capacitor placed across the power line. The reactive impedance of the capacitor forms a voltage divider with the source (source) impedance, which results in attenuating high frequency transients.
This simple approach can exhibit the following undesirable side effects:
1. Undesirable resonances occur with inductive components located elsewhere in the circuit, which results in high peak voltages.
2. High inrush currents occur during switching.
3. Excessive reactive loads occur in the voltage of the power supply system.
[0014]
These undesirable effects can be mitigated by adding a series resistor. However, the added resistance has the disadvantage of reducing the effect of clamping.
In order to successfully achieve maximum clamping, damping and absorption of transient overvoltage energy, highly permeable magnetic cores are incorporated into the above mentioned capacitors and damping resistors.
Second order tuning creates a critically damped RLC low pass filter. In this way, the undesired effects just mentioned can be eliminated. However, mere ordinary inductance does not work well. The special requirements for this magnetic core 15, hereinafter referred to as "L", are as follows.
[0015]
1) Since the characteristics of the capacitor are non-linear with respect to frequency but are linear with respect to current, the response characteristic of L with respect to current and frequency must be linear. The requirement of the response characteristic is shown in FIG. 4 as a hysteresis graph of the magnetizing force H with respect to the magnetic flux density B.
2) The magnetic core needs to be reset for each cycle of the ringing frequency, since the shock vibration wave cannot be statistically balanced as a pure sine wave with no DC component. As shown in the above graph, although this requirement is satisfied, it is noticed that the remanence Br is basically close to zero like the coercive force.
3) L must remain stable for frequencies fluctuating beyond 1 MHz to function at a preset level across all components of the shock ringing wave. This requirement is satisfied by incorporating a specific magnetic material into the waveform shaping filter of the present invention.
4) The change in the magnetic flux density with respect to the pulse permeability of the magnetic core L must stay within a specified range as shown in the graph of FIG.
The range of permeability described above is important because under random drive from the source, the inductance value must remain at its predetermined level.
[0016]
As shown in FIG. 6, the network basically takes the form of a series RLC circuit.
A valid equation for this system is given by:
^{d 2 i / dt 2 + R} / L · di / dt + i / (LC) = 0
^{s 2 + R / L · s} + ω 0 2 = 0
d / dt = s
However, d / dt = s routes _{S 1, S 2 = -R /} (2L) ± √ [(R / (2L) 2 -1 / (LC)]
The critical resistance is
R _cr = 2√ (L / C)
Is determined as follows.
Also, the corresponding damping ratio is
ζ = R / R _cr = R / 2√ (C / L)
It is.
The natural frequency is
ω _n = 1 / √ (LC)
And R / L = 2ζω _n
Given by
From the above, the characteristic equation is S ² + 2ζω _n S + ω _n ² .
[0017]
By realizing the special properties of the nanocrystalline core material, two important parameters ζ and ω _n in the above characteristic equation can and do influence the performance of the filter system. Its performance is focused on current channeling and tuning based on cut-off frequency characteristics and proper damping.
The damping ratio ζ is chosen such that the shock ringing transients can be processed and absorbed by the consumer R in the circuit (as shown in FIG. 2), and the final frequency ω _n is determined by the decade (10 Hz). ) Is determined so that a roll-off of -40 dB per can cause sufficient attenuation at high frequencies as required in a particular system.
A key point for the operation of the above-described filter is a combination of the core material and the circuit configuration.
[0018]
FIG. 7 is a schematic diagram showing two waveform shaping filters of the present invention connected to a single-phase power supply line. In this example, a single-phase motor 18 is shown connected to an AC power supply through lines 19 and 20. Two identical waveform shaping filters 22 are connected between each of the lines 19 and 20 and the neutral line 21. A separate ground line 23 is connected between the motor housing and ground.
The filter 22 includes the fuse 10, the soft magnetic coaxial amorphous toroidal (annular) inductor 12 connected in series with the fuse, and the capacitor 14 connected between the coaxial inductor 12 and the neutral line 21. Including. The MOV 26 and a winding having a magnetic core 28 and a resistor 16 connected in series to each other are connected in parallel to 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 ground or equivalent.
[0019]
FIG. 8 is a schematic diagram showing three waveform shaping filters 22 connected to a three-phase motor 36 in a three-phase Y-shaped network. Each filter 22 is connected between one of the phase lines 40, 42 or 44 and a neutral line 46. As in FIG. 1, a separate ground line 48 is connected between the case of the motor 36 and ground. Each of the filters 22 is the same as in FIG. 7, except that the component values change according to the applied voltage and the like.
[0020]
FIG. 9 is a schematic diagram showing three waveform shaping filters connected to the three-phase motor 50 in the three-phase delta network. In this case, the waveform shaping filter 52 is connected in the phase lines 54, 56 and 58. Each filter 52 is basically similar to the filter 22, except that the resistor 30, the lamp 32, and the magnetic core and winding 28 are all connected in series across the capacitor 24. This variation is a matter of design choice depending on the required effective resistance. The separated ground line 60 is connected between the case of the motor 50 and the ground.
[0021]
The above-described embodiments of the present invention are merely illustrative of the principles and are not intended to be limiting. The scope of the invention is to be determined from the claims, including their equivalents.
[Brief description of the drawings]
FIG. 1 is a graph showing a sine waveform distortion caused by a high frequency transient voltage superimposed on the sine waveform.
FIG. 2 is a schematic diagram of a basic waveform shaping filter system.
FIG. 3 is a schematic diagram of a voltage divider showing characteristics of a transient voltage suppression system.
FIG. 4 is a graph showing a typical BH curve with characteristics of a magnetic core in Applicants' system.
FIG. 5 is a graph showing pulse magnetic permeability versus magnetic flux density of a magnetic material of a magnetic core in the applicant's system.
FIG. 6 is a simplified equivalent RLC circuit showing characteristics of a transient voltage suppression system.
FIG. 7 is a schematic diagram of the waveform shaping filter system of the present invention when connected to a single-phase motor.
8 is a schematic diagram of the same waveform shaping filter system shown in FIG. 7 connected to a three-phase wye circuit.
FIG. 9 is a schematic diagram of a waveform shaping filter system of the present invention connected to a three-phase delta circuit.
FIG. 10 is a waveform showing a filter action.

Claims (20)

In a waveform shaping filter connected to an AC power supply,
Fuse and
Inductance means connected in series with the fuse;
A filtering network connected in series with a fuse and an inductance means, the filtering network including a varistor, a capacitor, and a parallel connection of a magnetic core inductor and a resistance means connected in parallel with the capacitor and the varistor and connected in series with each other. A waveform shaping filter comprising a circuit network. In a waveform shaping filter connected to an AC power supply,
Fuse and
A soft magnetic coaxial amorphous toroidal (annular) inductor connected in series with the fuse;
A filtering network connected in series with a fuse and a coaxial amorphous toroidal inductor, a capacitor, a varistor connected in parallel with the capacitor, and a magnetic core inductor connected in parallel with the capacitor and the varistor and connected in series with each other. And a filtering network including a resistor. 3. The waveform shaping filter according to claim 2, wherein the filter further includes a ramp connected in parallel with the resistor. 3. The waveform shaping filter of claim 2, wherein the filter further comprises a ramp connected in series with the magnetic core inductor and the resistor. 3. The waveform shaping filter according to claim 2, wherein the magnetic core inductor has a high initial magnetic permeability, a low loss, and a high saturation magnetic flux density. 3. The waveform shaping filter according to claim 2, wherein the filtering network is a critically damped low-pass filter. 3. The waveform shaping filter according to claim 2, wherein a response characteristic of the magnetic core inductor is substantially linear with respect to current and frequency. 3. The waveform shaping filter according to claim 2, wherein the residual magnetism of the magnetic core reactor is substantially zero. In a waveform shaping filter network system connected to an AC power supply including two power lines and one neutral line,
A first filter network connected between one power supply line and the neutral line, and a second filter network connected between the other power supply line and the neutral line, Each of the first and second filter networks
A soft magnetic coaxial amorphous toroidal inductor connected to one power line,
A low-pass filter connected in series with said coaxial amorphous toroidal inductor, comprising a capacitor, a varistor, and a parallel connection of an inductance member having a magnetic core inductor and a resistor connected in series with each other. A waveform shaping filter network system comprising first and second filter networks consisting of a pass filter; The waveform shaping filter system of claim 9, wherein the system further comprises a ramp connected in parallel with each of the resistors. In a waveform shaping filter network system connected to an AC power supply,
A first filter network connected between one side of the power supply and the neutral line, and a second filter network connected between the other side of the power supply and the neutral line, the first filter network comprising: And each of the second filter networks
A fuse and a soft magnetic coaxial amorphous toroidal inductor connected in series;
A low-pass filter connected in series with the fuse and the coaxial amorphous toroidal inductor, comprising a capacitor, a varistor connected in parallel with the capacitor, and a magnetic capacitor connected in parallel with the capacitor and the varistor and connected in series with each other. A waveform shaping filter network system comprising first and second filter networks comprising a low pass filter comprising a core inductor and a resistor. The waveform shaping filter network system according to claim 11, wherein the magnetic core inductor has a high initial permeability, a low loss, and a high saturation magnetic flux density. The waveform shaping filter network system according to claim 11, wherein the residual magnetism of the magnetic core reactor is substantially zero. The waveform shaping filter network system of claim 11, wherein the system further comprises a ramp connected in parallel with each of the resistors. In a waveform shaping filter network system connected between a neutral line and a three-phase Y-connected AC power supply having a three-phase line, each is connected between one of the three-phase lines and the neutral line. First, second and third filter networks, each of these filter networks comprising:
A soft magnetic coaxial amorphous toroidal inductor connected to one of the three phase lines;
A filter connected in series with a coaxial amorphous toroidal inductor, comprising: a capacitor; a varistor connected in parallel with the capacitor; and a magnetic core inductor and a resistor connected in parallel with the capacitor and the varistor and connected in series with each other. A waveform shaping filter network system comprising: The waveform shaping filter network system of claim 15, wherein the system further comprises:
A waveform shaping filter network system including a fuse connected between each of the three phase lines and the coaxial amorphous inductor. The waveform shaping filter network system according to claim 15, wherein the magnetic core inductor has a high initial permeability, a low loss, and a high saturation magnetic flux density. In a waveform shaping filter system connected to a three-phase delta connected AC power supply having a three-phase line,
The system comprises first, second and third filter networks,
A first filter network is connected between the first phase line and the second phase line;
A second filter network is connected between the second phase line and the third phase line;
A third filter network is connected between the third phase line and the first phase line;
Each filter network is
A soft magnetic coaxial amorphous toroidal inductor connected to one of the phase lines;
A low-pass filter connected in series with a coaxial amorphous toroidal inductor, comprising a capacitor, a varistor connected in parallel with the capacitor, and a magnetic core inductor connected in parallel with the capacitor and the varistor and connected in series with each other. A waveform shaping filter system comprising a member and a resistor. 20. The waveform shaping filter system according to claim 18, wherein the system further comprises a fuse connected between each of the phase lines and the coaxial amorphous inductor. 20. The waveform shaping filter system of claim 18, wherein the system further comprises a ramp connected in series with each of the resistor and the magnetic core inductor member.

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