RU2051466C1 - Noise suppressing device - Google Patents

Abstract

FIELD: secondary power supplies. SUBSTANCE: device has case accommodating input transformer 2 and output transformer 3 where input transformer secondary winding 12 and output transformer primary winding 13 are interconnected and primary leads of input transformer and secondary leads of output transformer are connected, respectively, to terminals of device used for connection to power source and load; resonance-tuned assembly built up of parallel-connected choke coil 15 and capacitor 16 having variable inductance and capacitance is connected in parallel with input transformer secondary winding and output transformer primary winding. EFFECT: improved efficiency of noise suppression. 2 cl, 1 dwg

Description

 The invention relates to electrical engineering and is intended to protect against conducted impulse noise power devices of computer equipment, automated control systems, measuring and other highly sensitive electronic equipment.

 In addition, to protect against electromagnetic interference both consumers and power supply networks, the invention may find application in networks with isolated neutral (for example, ship).

 Known noise-protective transformer insert [1] containing two metal shielded volumes in which the first and second transformers with filters are located, the secondary winding of the first transformer and the primary winding of the second transformer are made in the form of multilayer strip lines and are connected to each other through two series-connected filters, and one of the connection points of the first and second filters is connected to shielded volumes and is grounded.

 In addition, in order to increase noise suppression, two additional capacitors are introduced into each shielded volume, which are included between the common point of the shielded volumes and the corresponding layers of the strip windings of the first and second transformers.

 This device has high impulse suppression efficiency.

However, the device has significant disadvantages:
low efficiency due to large losses in a high-current low-voltage circuit formed by strip windings and two series-connected filters;
the complexity and low technology of manufacturing strip windings of transformers;
soft load characteristic due to losses in the low-voltage circuit and in the magnetic circuits of throttle filters and transformers;
low overall dimensions.

 The closest in technical essence to the invention is a device [2] which contains two transformers placed in a common housing. The input transformer, with its primary winding, is connected to the input terminals for connecting to an electric power source, for example, to the power supply network, and the secondary winding is connected to the primary winding of another output transformer, the secondary winding of which is connected to the output terminals of the device for connecting to the electric power receiver.

 Thus, the secondary winding of the input transformer and the primary winding of the output transformer form an inner circuit in which the connection point of the second terminal of the secondary winding of the input transformer and the first terminal of the primary winding of the output transformer is connected to the housing.

 This device has a small equivalent passage capacity due to the use of sequential switching of transformers with separate windings and the possibility of draining the energy of impulse noise to the ground (to the housing) due to its connection to the specified connection point, which greatly prevents the passage of high-frequency interference pico-nano- microsecond range.

 However, pulsed interferences with a longer duration (from tens and hundreds of microseconds to units of milliseconds) are transformed into secondary windings directly through the ferromagnetic cores of the transformers and are attenuated slightly, it is these interferences that have maximum amplitude and pulse energy and are one of the main causes of malfunctions and output out of order electronic circuits.

 The purpose of the invention is to increase the suppression efficiency of conducted impulse noise with any pulse duration.

 The goal is achieved due to the fact that in a known device containing input and output transformers, the secondary winding of the input transformer and the primary winding of the output transformer are interconnected, and the terminals of the primary winding of the input transformer and the secondary winding of the output transformer are connected respectively to the terminals of the device for connecting to source and receiver of electricity, in order to increase the efficiency of noise suppression, parallel to the secondary winding of the input transformer and primary On the output winding of the output transformer, a resonant unit is included, which is a parallel-connected inductor and capacitor.

 The inclusion in the circuit of a known device of a resonant assembly in the form of a parallel-connected inductor and capacitor is essentially new in relation to the prototype and allows not only several orders of magnitude to increase the efficiency of suppression of impulse noise in relation to the prototype, but also to weaken the low-frequency harmonics of the supply voltage at the output of the device, which allows you to get electricity of higher quality.

 The invention is illustrated in the drawing.

 The interference suppression device comprises a housing 1, in which an input transformer 2 and an output transformer 3 are located, the primary winding 4 of the input transformer 2 being connected to the terminals 5 and 6 of the noise suppression device for connecting to an electric power source 7, for example, an electric network. nutrition. The secondary winding 8 of the output transformer 3 is connected to the terminals 9 and 10 for connecting to the power receiver 11. The secondary winding 12 of the input transformer 2 and the primary winding 13 of the output transformer 3 are interconnected, forming an internal circuit. The interference suppression device also includes a resonant assembly 14 made in the form of a parallel connected inductor 15 and a capacitor 16, as well as shielding baffles 18 and 19 installed inside the housing, the shielding baffle 18 being installed between the input transformer 2 and the resonant assembly 14, and the shielding baffle 19 between the resonant node 14 and the output transformer 3. They have holes 20, 21, 22 and 23 for introducing conductors connecting the windings 12 and 13. Point 17 of the inner circuit formed by connecting the winding 12 input one transformer 2 and the primary winding 13 of the output transformer 3, is grounded to the housing 1.

 For the most efficient operation of the noise suppression device, it is necessary that the resonant assembly 14 is tuned in resonance with the frequency of the electric power source, in this case the power supply network.

 The suppression device operates as follows.

 Electric power of alternating current coming from the network to the primary winding 4 of the input transformer 2 is transferred to its secondary winding 12, the load of which is the resonant node 14. The voltage removed from the terminals of the resonant node 14 is supplied to the primary winding 13 of the output transformer 3, and from the secondary winding 8 of the output transformer 3 voltage is supplied to the power receiver 11.

 An increase in the noise suppression efficiency in a wide frequency range is achieved due to a significant change (decrease) in the resistance of the resonant node 14 at frequencies other than the frequency of the supply network.

 In the absence of pulsed interference in the supply network, the resonant node 14 practically does not affect the transmission of electricity from the secondary winding 12 of the input transformer 2 to the primary winding 13 of the output transformer 3, the resistance of the resonant node 14 is maximum and the noise suppression device operates as a transformer with a small passage capacity and a common transformation ratio close to unity.

 If there is pulsed noise in the supply network passing into the secondary winding 12 of the input transformer 2, they are bridged by the low resistance of the resonant node 14 and are significantly attenuated. At the same time, the output of the noise suppression device achieves attenuation of symmetric and asymmetric impulse noise by several orders of magnitude.

 In addition, the presence in the device of a resonant assembly 14 tuned to the frequency of the supply network attenuates the low-frequency and high-frequency harmonics of the output voltage and allows obtaining higher-quality electric energy.

 The noise suppression device is invariant and provides effective protection for both consumers from impulse noise arising in the network, and the network itself from interference arising on the consumer side.

 To confirm the correctness of the adopted technical solution, a valid model of the noise suppression device was manufactured and tested, in which transformers 1 and 3 were used with a capacity of 500 VA at 220 V, 50 Hz. The transformation ratio is equal to one.

 The resonant node 14 consists of a choke 15 and a capacitor 16.

Choke Inductance 450 mg
Capacitor Capacitance 16 μF
Power supply 220 V, 50 Hz
Load current (max) 2 A
Pulsed symmetric and asymmetric interference was generated at the input of the device by a simulator of pulse interference and recorded at the input (in the mains supply) and at the output of the device (in the load) with a C 8 14 oscilloscope.

 The maximum (amplitude) value of the impulse noise reached a value of 1500 V (1.5 kV).

The following data were obtained:
A pulse lasting up to 1 μS 70 80 dB (attenuation of 5 10 thousand times).

 A pulse with a duration of up to 10 μS 50 60 dB (attenuation of 500 to 1000 times).

 Pulse lasting up to 100 μS 30 40 dB (attenuation by 50 100 times).

 A pulse lasting up to 1000 μS 20 30 dB (attenuation tens of times).

 From the experimental data it can be seen that the proposed noise suppression device provides a reduction in the amplitude of pulsed noise by several orders of magnitude, which guarantees protection of the energy consumer (receiver 11) and its reliable operation.

 The use of the invention in the national economy will provide an economic effect, consisting in reducing damage due to the prevention of failures and failure of computer equipment, automated control systems, technological complexes and other electrical consumers.

Claims (2)

 1. INTERFERENCE DEVICE, comprising a housing with input and output transformers located in it, the secondary winding of the input transformer and the primary winding of the output transformer are interconnected, and the terminals of the primary winding of the input transformer and the secondary winding of the output transformer are connected respectively to the terminals of the device for connecting to the source and a power receiver, characterized in that, in order to increase the efficiency of noise suppression, in parallel to the secondary winding of the first transformer and the primary winding of the output transformer, a resonant unit is included, which is a parallel-connected inductor and capacitor.  2. The device according to claim 1, characterized in that the resonant node is tuned in resonance with the frequency of the electric power source.