RU193892U1 - Power supply - Google Patents

Abstract

The utility model relates to lifting equipment and can be used to power control systems and overload protection of electric hoisting machines. The power supply contains a step-down transformer, a bridge-type rectifier, a filter for smoothing ripples at the output of the rectifier, and a voltage stabilizer made on the transistor. The first high-frequency noise filter at the input of the power source, the input voltage surge suppressor, the voltage surge suppression device on the secondary winding of the step-down transformer, the second high-frequency noise filter on the transformer secondary winding, the rectified ripple voltage surge suppression device, a three-link ripple smoothing filter are introduced into the power supply at the output of the rectifier and three safety devices for overload protection but the input circuit, the secondary winding of step down transformer and rectifier. In this case, the voltage stabilizer is made on a composite transistor and a precision adjustable voltage reference source. The technical result is an increase in the accuracy and stability of the voltage at the output of the power source and a decrease in the ripple of the rectified voltage during its operation in conditions of unstable, constantly changing parameters of the industrial network, as well as an increase in its reliability in unfavorable conditions of industrial production. 8 s.p. f-ly, 7 ill.

Description

The technical field to which the utility model relates.

The utility model relates to lifting equipment and can be used mainly for powering control systems and overload protection of electric hoisting machines, as well as for powering measuring and recording equipment installed at industrial facilities, such as rolling mills, production lines, conveyors, processing machines, weighing systems, process control and management systems.

State of the art

The measuring and recording equipment installed at industrial facilities is powered in the vast majority of cases from the same industrial network 380 V 50 Hz, from which all industrial equipment is powered. Due to the high degree of loading of such a network, which constantly changes during operation from turning on or off a particular powerful load and with significant reactive components (inductive, capacitive), the voltage of the industrial network is constantly changing. These changes are both short-term in nature (surges and voltage dips within a fraction of a second), and long-term in nature (decrease and increase in voltage relative to the nominal value within a few seconds and up to several hours), and have an extremely adverse effect on the industrial equipment itself ( up to failure), and to measuring and recording equipment containing sensors, sensitive elements and electronic components, which differ, along with high sensitivity to vapors Tram Measured and recorded processes are very sensitive to the parameters of its power. And those significant changes in the parameters of the industrial network that industrial equipment can withstand for measuring equipment in most cases turn out to be unacceptable: they lead not only to a distortion of the parameters of the recorded processes, but also most often to failure of the entire measuring and recording system, without which modern industrial equipment simply cannot work. And the cost of modern measuring systems is often comparable to the cost of equipment, and in some cases it can exceed it.

In addition to a stable power supply, modern measuring and recording systems impose very serious requirements on the quality of power supply, and first of all on the level of alternating voltage ripples in the composition of the rectified voltage. These ripples, among which primarily pulsations with a frequency of 50 and 100 Hz and high-frequency interference in the range of 10-1000 kHz, have a very strong effect on the operation of low-current sensors (on their accuracy), and are also extremely unfavorable in terms of ensuring the accuracy of the output signal for analog-to-digital converters (ADC), which are part of almost all analog sensors. Requirements for the level of alternating voltage ripples in the composition of the constant voltage of the sensor power supply for most sensors range from 0.1% to 1% of the sensor voltage. This for a 24 V supply voltage is 2-24 mV. For example, for high-quality and reliable operation of load cells with a constant voltage of 10 V, these ripples should be even less, about 1-5 mV.

And if the first problem (fluctuations in the input voltage of the power supply) to some extent successfully cope with pulsed power sources, then they cannot solve the second problem at all and cannot solve it by virtue of the very principle of pulsed conversion of the mains voltage to the voltage of the sensors. The operating frequencies of switching power supplies lie in a wide frequency range: from 10 to 1000 kHz, and in some cases even higher. And these operating frequencies of pulsed power supplies are precisely the source of powerful high-frequency interference for sensors, for ADCs, and for other analog and digital equipment. At the same time, the source of interference is often located in the immediate vicinity of the equipment, which interferes with its interference, and often simply does not allow it to function normally. Because of this, the use of switching power supplies with measuring and recording systems is problematic, and most often impossible. The creation of special filters for such interference is a non-trivial, complex, expensive and really unresolved task today.

The best option for powering the measuring and recording systems of industrial automation can be a purely analog stabilized power supply operating in a very wide range of input power supply voltages (as shown by repeated practical measurements in the workshops of industrial enterprises for nominal 380 V 50 Hz, this is 280-560 V), providing output stabilized voltage of 24 V, or other voltages required for the equipment, and a low level of alternating voltage ripples with a frequency of 50 and 100 Hz and ysokochastotnogo noise. Yes, an analog power supply is characterized by a low efficiency (not more than 30-50%), especially when working in a wide range of input voltages, however, in industrial conditions, when the consumption of industrial equipment is tens or hundreds of kW / h, a power supply with a power of 30- 60 W consumes a tiny fraction of energy in the overall energy balance of a plant or workshop, therefore this fact cannot be considered negative under these conditions, or having any noticeable effect and significance in the total m power consumption. At the same time, the power supply provides the level and quality of power supply in the above conditions of the mains, which are quite sufficient for the functioning of measuring and recording systems installed on industrial equipment.

Typically, industrial automation devices receive power from an industrial network of three-phase alternating current with a voltage of 380 V 50 Hz. Obtaining a low voltage voltage (12-24 V) from a three-phase voltage is very attractive from the point of view of obtaining a constant voltage with a relatively low ripple due to the rectification of all three phases of the alternating voltage. However, this increases the frequency of the pulsations of the first harmonic. And the most important thing that limits the application of this method is the need to manufacture a step-down three-phase low-power transformer (50-200 W). The manufacture of such a low-power transformer is quite laborious and practically not mastered by the industry, its dimensions, as well as the cost of development and manufacture, significantly exceed the similar parameters of low-power single-phase transformers. Therefore, practically obtaining low-voltage direct voltage of low power from a three-phase voltage of 380 V 50 Hz did not find application in industry. Although schemes of this kind are known and described in the technical literature. In practice, when creating power sources for industrial automation units and safety systems of hoisting cranes, single-phase voltage is used, i.e. or one of the phases of a three-phase network, i.e. 220 V 50 Hz, or, which is especially typical for hoisting cranes, where in most cases there is no neutral fourth wire, the linear voltage of a three-phase network is used, i.e. 380 V 50 Hz, i.e. voltage between wires of any two phases.

A power supply device of a crane safety system is known, which contains an autonomous power source, as well as a generator made with the possibility of mechanical interaction with a crane cargo or boom rope, as well as with the possibility of converting the mechanical movement of this rope or block into electrical energy. The generator output is connected to an autonomous power source, which is made in the form of a battery or capacitor. When the crane and, accordingly, the generator, the battery or capacitor is recharged. The energy stored in the battery or capacitor is used to power the safety system at times when the crane mechanisms are stationary (RU 2310598 C1, B66C 13/18, 15/06, 23/88, 11/20/2007).

The voltage at the output of the generator is characterized by an unstable value, significant surges and dips, depending on the intensity and stability of rotation of the generator. The battery in this circuit is used not only as an energy storage device, but also as a filter to suppress this instability and low-frequency (up to 50-80 Hz) voltage surges and dips. But the efficiency of this filter is low, especially in the frequency range, large 100-200 Hz. And electronic stabilizers usually used in such circuits are capable of suppressing only significant voltage surges, i.e. do not completely solve the problem of reducing ripple of the variable component of the output voltage. Therefore, the use of such a scheme is impractical on electric lifting machines and mechanisms, such as bridge, gantry and diesel-electric cranes, hoists and winches operating in the shops of industrial enterprises, where the energy of the industrial three-phase network voltage of 380 V 50 Hz is used as energy. Because this energy is always there during operation, and if for some reason it disappeared (accident, etc.), then the operation of all equipment, including hoisting machines and cranes, will be paralyzed. And the fact that the safety device also stops working does not matter.

The closest to the proposed utility model for the combination of essential features is a power source, which includes a step-down transformer, a rectifier, a first electric filter for smoothing ripples at the output of the rectifier, a parametric stabilizer made on a zener diode and transistor, and a second electric filter for smoothing ripples at the output parametric stabilizer. The primary winding of the transformer is connected to the AC mains, and the secondary winding is connected to the rectifier, from the output of which the rectified ripple voltage is supplied to the first electric filter and from it to the input of the parametric stabilizer, from the output of which voltage is supplied to the second electric filter and then to load (MA Shustov. Practical circuitry.) Book 2. “Power supplies and stabilizers. 2nd ed., eras. - M.: Dodeka-XXI Publishing House, Altex, 2007, p. 72- 73).

This device is a general-purpose direct current source that provides a load with a stabilized voltage during fluctuations in the AC network that meets generally accepted standards (from -15 to + 10% relative to the nominal value of 220 or 380 V). There is no evidence to refute this claim in the description. A typical stabilizer circuit is designed to maintain a stable output voltage with minor fluctuations in the supply voltage. However, even a home network often gives significantly large deviations from the nominal, which lead to failure and failure of the power source. If we talk about an industrial network, where the power consumed by many machines, mechanisms, lifting devices exceeds tens and hundreds of kW, and these mechanisms do not work constantly, but turn on and off unpredictably, they change the operating mode and power consumption, where they act as the load significant reactive elements (capacitance, inductance), then under such conditions the described circuit of the power supply will work inefficiently, it will not be able to provide the accuracy necessary for measuring equipment Nia output voltage, its stability and low ripple output voltage variable component. And with significant changes in the voltage of the supply network, the current flowing through the zener diode will exceed the value acceptable for the selected zener diode, as a result of which the zener diode, and after it the transistor, will fail. Similarly, with significant increases in input voltage, a step-down transformer may fail due to breakdown of insulation and inter-turn circuit in the primary or secondary windings. That is, this device does not contain any measures and circuit solutions to combat significant input voltage spikes. But the stabilizer itself cannot cope with this problem.

The described device is also not able to fully perform its functions with significant drops in input voltage. The range of permissible currents flowing through the zener diode is small. As a rule, at a zener diode, the ratio of the maximum stabilization current to the minimum current does not exceed 20-30. This at 24 V of the rated voltage at the output of the power supply allows this device to efficiently perform the stabilization task when the input voltage changes from 28 to 42 V, which corresponds to the voltage range of the supply network 310-440 V (at a nominal value of 380 V), i.e. 380 ± 20%. This range is clearly insufficient for equipment powered by real industrial networks, in which voltage changes are much larger. The real network of an industrial enterprise can produce at a nominal value of 380 V minimum voltages of 270-290 V and maximum 560-580 V, and these are not short-term pulses with a duration of tens of microseconds, but rather long-term changes that can last from hundreds of milliseconds to tens of minutes or even up to several hours.

The described device also does not contain solutions to combat short-term pulse emissions, which are almost always present in the industrial network due to frequent switching on and off of industrial equipment. It also does not contain circuitry to protect against overloads and short circuits in the load.

The specific design of this device is not shown, which suggests that it is hardly intended for use in industrial conditions, which, in particular, imply protection against penetration of foreign objects into the device (particles, dust, moisture, etc.), which is regulated norms, the so-called Ingress Protection, or IP for short (for example, IP65, where the first digit 6 indicates that the device is dustproof, and the second digit 5 indicates that the device is protected from water flows). As a rule, measuring and electronic devices operating in general industrial conditions should be performed with a protection level of at least IP65.

In addition, in the conditions of the workshop, erroneous unintentional connections to the output of this device of other voltage sources are possible, which can also lead to the failure of this device and an emergency in the workshop.

And finally, working with such a device and its diagnostics are really difficult due to the lack of any indication of the normal functioning of the device.

Utility Model Disclosure

The task to which the proposed utility model is directed is to create a power source, mainly for the safety and control system of a lifting machine, with increased accuracy and voltage stability at its output and providing high-quality and reliable power to measuring and recording equipment under conditions of unstable, constantly changing parameters industrial network, in the presence of both short-term and long-term deviations of the mains voltage from the nominal values.

Another objective of this utility model is to protect the power supply from exceeding the power consumption of the permissible value, as well as from a short circuit in the external circuit and from inadvertently supplying voltage to the output of the power supply from other external sources.

An additional objective of this utility model is also to increase the reliability and reliability of the power supply in adverse industrial conditions.

The stated technical problems are solved in that a power source containing a step-down transformer, a bridge-type rectifier, a filter for smoothing ripples at the output of the rectifier and a voltage regulator made on the transistor, according to a utility model, include: the first high-frequency interference filter at the input of the power source; input voltage surge suppression device; voltage surge suppression device on the secondary winding of a step-down transformer; a second high-frequency interference filter on the secondary side of the transformer; rectified ripple voltage suppression device; three-link filter for smoothing ripple at the output of the rectifier; and three safety devices to protect against overload, respectively, of the input circuit, the secondary winding of the step-down transformer and rectifier. In this case, the voltage stabilizer is made on a composite transistor and a precision adjustable voltage reference source. The primary winding of the step-down transformer is connected to the input of the power source through a first safety device, a first high-frequency interference filter at the input of the power source and an input voltage surge suppression device connected in series. The secondary winding of the step-down transformer is connected to the input of the rectifier through a second safety device connected in series, a voltage surge suppression device on the secondary winding of the step-down transformer and a second high-frequency interference filter. The output of the rectifier is connected to the outputs of the power supply through a third safety device, a device for suppressing the emission of the rectified ripple voltage, a three-link filter for smoothing the ripple at the output of the rectifier, and a voltage regulator.

The achievement of the technical result is also facilitated by the private essential features of the utility model.

The first high-frequency interference filter at the input of the power supply and the input voltage surge suppression device are combined into a single unit containing resistors common to this device and filter

The first high-frequency interference filter at the input of the power supply and the input voltage emission suppression device are multistage.

A Darlington transistor mounted on a metal radiator through a heat-conducting electrically insulating gasket is used as a composite voltage stabilizer transistor.

The voltage stabilizer is connected to the output of the power source through the device to protect the output circuit from overload, short circuit and unintentional connections to it of external power sources, including a fourth safety device.

The step-down transformer is made on a toroidal core filled with a compound.

Safety devices are made in the form of fuses.

The primary winding of the transformer and the output of the power source are made respectively with the voltage indicator of the network and with the voltage indicator at the output of the power source.

Indicators are made on LEDs.

The essence of the utility model is as follows.

Introduction to the power source of the first high-frequency interference filter at the input of the power source provides suppression of interference coming to the source from the mains and from neighboring units of industrial equipment operating in the workshop and powered by switching power supplies. This filter protects the electronic load blocks and measuring circuits of the sensors from failures and errors in operation.

The introduction of an input voltage suppression device into the power source provides suppression of powerful impulse noise coming to the power source from the mains and from neighboring units of industrial equipment operating in the workshop. This filter protects the transformer, the rectifier, the voltage regulator, and even the electronic load blocks from failure and energy damage.

The presence of a voltage surge suppression device on the secondary winding of a step-down transformer provides suppression of residual impulse noise passing through the transformer. This filter protects the failure and energy damage of the rectifier, voltage regulator and electronic load blocks.

The presence of a second high-frequency interference filter on the secondary side of the transformer provides suppression of interference caused by pickups passing through the transformer from the mains, interference, as well as pickups caused by the power supply circuit itself and magnetic fields from the operation of the surrounding equipment.

The introduction of a rectified ripple voltage suppression device into the power supply makes it possible to maximally approximate the shape of the rectified ripple voltage to the "ideal" one, i.e. consisting of pure half-wave sinusoids with a frequency of 100 Hz to improve subsequent filtration and stabilization.

Introduction to the power supply of a three-link filter allows you to bring the ripple level at a frequency of 100 Hz to 100 - 500 mV. At the filter output, the voltage can already be called constant, and for some not very critical applications this level of ripple can be quite acceptable.

The implementation of a voltage stabilizer on a composite transistor and an adjustable precision reference voltage source allows both precise stabilization of the output voltage in a very wide range of input voltage variations and additional filtering of residual ripples. The transistor here acts on the one hand as a filter for suppressing alternating voltage ripples, and on the other hand as a signal power amplifier of an adjustable precision reference voltage source, in which a small control current of an adjustable precision reference voltage source and, accordingly, the base current of the transistor controls a large current flowing in collector - emitter circuit. The use of an adjustable precision precision voltage source in the stabilizer allows to obtain increased accuracy of stabilized voltage maintenance (0.5-1%). In addition, the adjustable precision reference voltage source used in the proposed technical solution provides increased stabilization accuracy due to the presence of feedback between the anode-cathode current through it and the output voltage of the stabilizer. Due to this, it is possible, including, to significantly expand the range of variation of permissible input voltages (from 30-32 V to 65-75 V) and at the same time to keep the output voltage (24 ± 0.2 V) almost unchanged.

The combination of the first high-frequency interference filter at the input of the power supply and the input voltage emission suppression device into a single unit containing resistors common to this device and filter allows the filter to be made more compact and resistant to each of the individual factors (interference, discharge, failure), and to their combined effect.

The implementation of the first high-frequency interference filter at the input of the power supply and the input voltage suppression device with multi-link (multi-stage), increases the efficiency of this filter, and also increases the reliability and stability of powerful interference suppression, since the interference energy is distributed between all parts of the filter, i.e. only one part of the total interference energy acts on one filter element.

The use of a Darlington transistor as a compound transistor helps maintain a highly stable voltage in a wide range of input voltage variations, and the installation of a Darling transistor on a metal radiator through a heat-conducting electrically insulating gasket improves heat dissipation from this transistor.

Connecting a voltage stabilizer to the output of the power source through the device protecting the output circuit from overload, short circuit, and unintentional connections of external power sources to it, including the fourth safety device, can improve the reliability and reliability of the power source in adverse industrial production conditions.

The implementation of a step-down transformer on a toroidal core filled with a compound allows you to protect the transformer from moisture, water, water and other vapors, and thereby additionally protect it and the power source from adverse industrial production conditions.

The implementation of safety devices in the form of fuses is preferred for devices operating from an unstable network.

Performing the primary winding of the transformer and the output of the power source, respectively, with the voltage indicator of the network and the voltage indicator at the output of the power source, provides the ability to visually determine the operability of the power source and, if necessary, accelerate the diagnosis of faults and localize these malfunctions.

The technical result from the use of this utility model is to increase the accuracy and stability of the voltage at the output of the power source and reduce the ripple of the rectified voltage during its operation in conditions of unstable, constantly changing parameters of the industrial network, as well as to increase its reliability in unfavorable conditions of industrial production.

The following description of the proposed power source and the accompanying drawings are intended only to illustrate the utility model and in no way limit the scope of the utility model formula.

Brief Description of the Drawings

In FIG. 1 shows a functional diagram of the proposed power source; in FIG. 2 - voltage surge suppression device with a high-frequency input interference filter; in FIG. 3 - step-down transformer with a voltage indicator; in FIG. 4 - rectifier); in FIG. 5 - filter for smoothing ripple at the output of the rectifier; in FIG. 6 - voltage stabilizer; in FIG. 7 - device for protecting the output circuit from overload, short circuit and inadvertent connections to it of external power sources.

Utility Model Implementation

The power source, for example, a load limiter of a bridge-type crane (hereinafter referred to as the limiter) is made in the form of a voltage converter of an industrial AC 380 V 50 Hz (input voltage) to an intermediate stabilized DC voltage of 24 V.

The design of the limiter is not the subject of this utility model. The limiter contains a control device installed in the crane cabin, a strain gauge force sensor installed in the hinge node of the hook suspension, and a combined communication line between the force sensor and the control device.

The power supply includes:

- the first safety device 1 to protect against overload of the input circuit;

- input voltage surge suppression device 2, combined with a high-frequency input interference filter;

- step-down transformer 3 with a voltage indicator 4 on the primary winding of the transformer, made on the LED;

- a second safety device 5 for overload protection of the secondary winding of the step-down transformer;

- voltage surge suppression device 6 with a high-frequency interference filter on the secondary winding of a step-down transformer 3;

- rectifier 7;

- the third safety device 8 to protect the rectifier 7 from overload;

- a device 9 for suppressing emissions of a rectified ripple voltage;

- a filter 10 for smoothing voltage ripples at the output of the rectifier;

- voltage stabilizer 11;

- a device 12 for protecting the output circuit against overload, short circuit, and inadvertent connections of external power sources to it, including a fourth safety device 13.

The output of the safety device 13, which is the output of the proposed power source, is connected to the indicator 14 of the presence of voltage at its output, made on the LED. Its circuit is similar to that of the indicator 4 of the presence of mains voltage on the primary winding of the transformer 3, but the value of the resistor has a different rating, since here the voltage has a different value.

The primary winding of the step-down transformer 3 is connected to the inputs of the power source through a series-connected first safety device 1 and a device 2 for suppressing input voltage spikes, combined with an input high-frequency interference filter.

The secondary winding of the step-down transformer 3 is connected to the inputs of the rectifier 7 through a second safety device 5 and a voltage surge suppression device 6 with a high-frequency noise filter on the secondary winding of the step-down transformer connected in series.

The outputs of the rectifier 7 are connected to the outputs of the power source through a third safety device 8 connected in series, a rectified ripple voltage suppression device 9, a filter 10 for smoothing ripples at the rectifier output, a voltage stabilizer 11 and an output circuit protection device 12 from short circuit and unintended connections to it external power sources, including a fourth safety device 13.

There are many known safety device designs 1, 5, 8, and 13. The simplest and most effective are self-healing and fuses. Resettable fuses are convenient in that they themselves repair a broken circuit after removing overload conditions. However, they have very large variations in the magnitude of the response current and, in addition, a significant delay in the response time, which can reach units of seconds. Fuses require replacement after tripping and also have some variation in the tripping conditions, however, the parameters of their tripping at the current level of development of fuse technology are much higher and more accurate than for self-resetting fuses. In addition, the phenomenon of “aging in time” and as a result of repeated tripping is inherent in self-healing fuses. For these reasons, fuses are more preferable for devices operating from an unstable network.

From the output of the first safety device 1, a high alternating voltage is supplied to the input of the voltage surge suppression device 2 and an input high-frequency interference filter. One possible implementation of such a combined 4-stage assembly is shown in FIG. 2. Generally speaking, a voltage surge suppression device and a high-frequency interference filter are different devices made on different radio elements. Device 2 for suppressing voltage surges of the supply network can be performed on one or more gas arresters. In particular, as shown in FIG. 2, it is made on two gas dischargers 15 and 16, a varistor 17 and protective symmetrical diodes 18 and 19, connected in series to ensure operation at a high voltage pulse (800-900 V) and separated by resistors 20-23 to bring together the moments of operation of these elements. The interference filter consists of ceramic or film capacitors 24-27 of various capacities (0.1-0.01 microfarads), also separated by resistors 20-23 for spacing the cutoff frequencies of the individual filter steps. That is, the voltage surge suppression device and filters combine the fact that they, as a rule, are multi-stage for reliability and increase their functionality, including, preferably, up to 4 steps. And these steps for the voltage surge suppression device and for the filter are separated by resistors. That is, the same resistor can act as a stage separator, an interference filter and a delay for a voltage surge suppression device. Therefore, the resistors of these devices are the same, and the capacitors of the filter stages are connected in parallel with the elements of the emission control device. Two gas arresters 15 and 16 are used here for greater reliability and stability of the suppression of powerful interference.

The power source is equipped with an indicator 4 of the mains voltage on the primary winding of the step-down transformer 3, made on the LED. To limit the current through the LED at the level of 5-30 mA, a resistor 28 is used. A low-power diode 29, turned on opposite the LED, is installed to protect the LED from the negative half-wave of the input voltage and block it. The LED does not have any effect on the functionality of the proposed power source, but its presence is useful in the analysis and localization of its malfunction.

The voltage surge suppression device 6 is made on a gas spark gap 30 and a symmetrical protective diode 31, the input high-frequency noise filter on the secondary winding is made on the capacitor 32, and the rectifier 7 is made on a traditional diode bridge (see Fig. 4). A rectifier pulsed voltage suppression device 9, made on the protective diode 33, is connected to the rectifier output 8 through the third safety device. The second safety device 5 is designed to protect the secondary winding of the step-down transformer 3 from overload, since the transformer is one of the most important and expensive nodes of the proposed power source.

The voltage surge suppression device 6 and the input high-frequency interference filter on the secondary winding of the step-down transformer 3 here, as well as at the input to the power supply, are designed to suppress alternating undervoltage surges and filter the interference. However, here their inputs are connected not to the mains supply, but to the output of the step-down transformer, which in itself is to some extent both an interference filter and a voltage surge suppression device. And voltage surges and interference have much lower intensity and power after the secondary winding, therefore, here these devices are single-link and without isolation resistors.

To protect the rectifier 7 from overloads, a third safety device 8 and a device 9 for suppressing possible surges of the rectified ripple voltage on the diode 33 are used. These voltage surges can come not from the output of the rectifier, but rather from the output of the power supply, or rather from the load connected to this source .

The device 9 for suppressing the emission of the rectified ripple voltage is connected to the filter 10 to smooth the ripple of the rectified voltage. Its circuit is shown in FIG. 5. This is a traditional three-link resistive-capacitive filter, consisting of two electrolytic capacitors 34 and 35 and one ceramic capacitor 36, interconnected by resistors 37-39. Here, a combination of electrolytic capacitors 34 and 35 with a ceramic capacitor 36 is used, since such a combination extends the effective filtering band. It is known that electrolytic capacitors filter well lower frequency ripples, especially mains ripples of 50 and 100 Hz, and ceramic capacitors better filter higher frequency noise. After the rectifier 7, the ripple has a value equal to the amplitude of the rectified voltage. After the filter, the ripple amplitude decreases to 100-300 mV, depending on the values of the capacities included in the filter. This is a constant voltage, which contains ripples. For some tasks, their level is already quite acceptable, but for tasks, especially related to measurements and the operation of analog-to-digital converters, this is an unacceptably high level, which leads to large errors when converting analog signals from measuring sensors to a digital code. And it needs to be significantly reduced to units or one or two tens of mV. In addition, the constant voltage is not stabilized, its value directly depends on the voltage value of the supply network, which is also unacceptable for measuring circuits and sensors, both in terms of accuracy and in terms of the possibility of normal functioning. To solve this problem, the output of the filter 10 is connected to the input of a voltage stabilizer 11 on a Darlington transistor 40 and an adjustable precision reference voltage source 41 (see Fig. 6). In the technical literature, such stabilizers are called parametric stabilizers with a transistor connected according to the emitter follower circuit. The transistor here plays the role of, on the one hand, the filter for suppressing alternating voltage ripples, and on the other hand, the signal power amplifier of an adjustable precision reference voltage source, in which a small current of a regulated precision reference voltage source and, accordingly, the base current of the transistor (0.5-30 mA ) controls a large current (0.2-4 A depending on the selected transistor) flowing in the collector-emitter circuit. Name shown in FIG. 6 stabilizer parametric possible with some stretch. In it, firstly, not a conventional zener diode (Zener diode) is used, but an adjustable precision source 41 of the TL431 family of voltage references. It is distinguished from a conventional zener diode by the increased accuracy of maintaining a stabilized voltage (0.5-1%), while a conventional zener diode cannot be characterized by such a parameter in general. Its stabilization voltage depends on the current flowing through it and has the form of an inclined curve on the graph. That is, for example, with a rated value of the zener diode 24 V, the real stabilization voltage in the range of permissible zener diodes can vary in the range from 21 to 27 V, i.e. talk about stabilizing the output voltage at a level of 1-2% can only be in a very narrow range of currents through the zener diode. Secondly, the adjustable precision reference voltage source of the TL431 family used in the proposed technical solution provides increased stabilization accuracy due to the presence of feedback between the anode-cathode current through it and the reference voltage on its control electrode. This voltage is removed from the voltage divider on resistors 42 and 43 and fed to the control input of an adjustable precision reference voltage source 41. That is, the stabilizer is some intermediate device between the parametric stabilizer and the compensation type stabilizer, it is simpler than the compensation, but much more accurate than the parametric one. Due to this, it is possible, including, to significantly expand the range of variation of permissible input voltages (from 30-32 V to 65-75 V), and at the same time to keep the output voltage (24 ± 0.2 V) almost unchanged.

The following circuit solutions also contribute to maintaining such a highly stable voltage over a wide range of input voltage variations. First, a Darlington transistor 40 is used as a composite voltage stabilizer transistor. This allows you to get a high current gain of up to 1000-2000, i.e. control of very small currents of the base of the transistor and obtaining high currents of the collector - emitter section, i.e. at the output of the power source. Secondly, the voltage supplied to the base of the transistor 40 is additionally filtered by a filter consisting of resistors 44 and 45 and capacitors 46 and 47. Thirdly, the voltage supplied to the control input of an adjustable precision reference voltage source 41 is filtered by a capacitor 48. V fourth, a filter from resistor 49 and capacitors 50 and 51 is also installed at the output of voltage stabilizer 11. These filters together not only suppress the AC component coming from the rectifier, but also suppress possible pickups from other circuit elements (e.g., step-down transformer 3). Fifthly, the diode 52 at the output of the stabilization circuit protects the transistor 40 from potential surges in the load and the communication line. At the same time, it does not have any harmful effect on the quality of stabilization, since the measurement of the output voltage by the control divider takes place behind it. That is, the diode 52 in its essence and functional purpose already belongs to the following node - the output circuit protection device 12.

The output of the voltage stabilizer 11 is connected to the input of the device 12 to protect the output circuit from unintentional connections of external power sources. Its circuit is shown in FIG. 7. The purpose of the diode 52 is described above. The diode 53 is protective and protects the adjustable precision reference voltage source 41 from short voltage surges. Diodes 54-57 and a safety device 13 protect the voltage stabilizer 11 from inadvertent connections of external power supplies in the polarity opposite to this power supply. If the voltage of an external power source in reverse polarity is accidentally connected to the output of the power source, the diodes 54-57 in this connection do not represent any resistance for it, the current caused by this external source will flow through them. The current will flow through the fourth safety device 13. This circuit actually creates a short circuit for the external source, as a result of which the safety device 13 trips, breaks the circuit and thereby protects the circuit of the voltage stabilizer 11 and the entire power source from undesirable external influences.

Structurally, the power supply is made in a separate metal case, equipped with a lid with a seal to protect the cavity of the body from external influences. A step-down toroidal transformer 3, filled with a compound, and a printed circuit board on which the components and elements of the proposed power supply are mounted are installed in the housing. In this case, Darlington transistor 40 is mounted on a metal radiator through a heat-conducting electrically insulating gasket, and the radiator, in turn, is attached to the metal casing of the power supply to improve heat dissipation from transistor 40 and reduce the size of the radiator itself.

The housing of the power supply is equipped with a cable entry located on its side surface for connecting to a crane power supply network with a rated voltage of 380 V AC and elements for electrical connection of the housing with the metal structure of the crane. Connectors are installed on the housing for powering other limiter nodes and exchanging information signals between these nodes, as well as for transmitting information and command signals from the limiter control device to other peripheral nodes of the crane. On the front surface of the housing there are two LED indicators.

The power source operates as follows.

An alternating voltage of the supply network 380 V 50 Hz (for all possible voltage fluctuations of a real industrial network from 280 to 560 V) is supplied through the first safety device 1 to the input of the voltage surge suppression device 2, combined with a high-frequency input filter. The gas spark gap 15 (16) has the longest delay time, but at the same time absorbs the largest part of the ejection energy, varistor 17 has a slightly lower response delay, but is also able to absorb less energy, the protective diodes 18 and 19 have the shortest delay time and are the first to operate , but they are also able to suppress a relatively small part of the emission energy. Resistors 20-23 will make it possible to bring the operation of these elements closer in time, to suppress the surge most efficiently and with the least losses for this device.

From the output of the voltage surge suppression device 2, the input voltage is supplied to the primary winding of a step-down transformer 3, equipped with an indicator 4 for monitoring the presence of mains voltage. At the output of the secondary winding of the transformer 3 there is a low voltage of 28-65 V 50 Hz. The value of this voltage depends on the input voltage (voltage on the primary winding) and is selected so as to provide a stable DC voltage of 24 V at the output of the power source for all possible voltage fluctuations of a real industrial network of 380 V (280-560 V).

The voltage at the output of the secondary winding of the transformer 3 is supplied through the second safety device 5 to the voltage surge suppression device 6 with an input high-frequency noise filter on the secondary winding of the step-down transformer and then to the rectifier 7.

The voltage from the outputs of the rectifier 7 is supplied to the outputs of the power source through a third safety device 8 connected in series, a device 9 for suppressing the emission of a rectified ripple voltage, a filter 10 for smoothing ripples at the output of the rectifier, a voltage stabilizer 11 and a device 12 for protecting the output circuit from short circuit and unintentional connections to it external power sources, including a fourth safety device 13.

The main circuit of the proposed power source is described above. It produces a stabilized voltage of 24 V. However, other voltages are required to power microprocessors, electronic circuits, and sensors of safety devices and control hoisting machines. Microprocessors and electronic circuits usually require 5 and 3.3 V. For strain gauges, in particular, a very high-quality stabilized voltage of 10 V. is required. The individual blocks and nodes of the safety device of the hoisting machine are located in different places at a sufficiently large (several and tens of meters) distance . Therefore, it is extremely undesirable to generate all these voltages in one power source, because when transmitting small voltages over considerable distances, noticeable losses in the resistance of the connecting cables occur. In addition, low voltages are more susceptible to interference and disturbances inherent in any electric lifting machine. Therefore, it is advisable to distribute a relatively high voltage of 24 V from the power supply to the blocks and nodes of the safety device through cables, which will give less and less interference. And already in each block and node specifically form from this voltage the other voltages necessary there: 10 V, 5 V, 3.3 V. Then these voltages will be less susceptible to disturbances and disturbances, and all blocks of the safety device will receive high-quality stabilized voltage .

In particular, to power the microprocessor of the limiter control device and electronic circuits, a linear voltage stabilizer can be used, the input of which is supplied with 24 V DC, and the voltage of 5 and 3.3 V is removed from the outputs of the linear stabilizer.

To power the limiter strain gauge, you can use a precision voltage stabilizer with a power amplifier on the transistor and a precision voltage reference source, equipped with a filter to smooth out the ripple of the rectified voltage. At the same time, 24 V DC voltage is supplied to the input of a precision voltage stabilizer, and 10 V DC is removed from the filter output.

The distributed structure of the proposed power source, in which the primary conversion of the high alternating voltage of the supply industrial network to an intermediate value of constant stabilized voltage is carried out in a separate independent unit, the casing of which can be mounted on the construction of an electric crane outside its cabin, eliminates the possibility of a crane operator being struck by high voltage and other maintenance personnel, and ensures the transfer of this intermediate stabilizer th e voltage connecting cables to other individual blocks of safety and control systems of hoisting machines, a further transformation of the intermediate voltage in each of the blocks into a voltage with parameters necessary and sufficient for the operation of the unit.

Industrial applicability

The claimed power source can be manufactured industrially at the instrument-making plant using modern electronic components and technologies.

Claims (9)

1. A power source containing a step-down transformer, a bridge-type rectifier, a filter for smoothing ripples at the output of the rectifier and a voltage stabilizer made on the transistor, characterized in that it includes: the first high-frequency interference filter at the input of the power source; input voltage surge suppression device; voltage surge suppression device on the secondary winding of a step-down transformer; a second high-frequency interference filter on the secondary side of the transformer; rectified ripple voltage suppression device; three-link filter for smoothing ripple at the output of the rectifier; and three safety devices for overload protection, respectively, of the input circuit, the secondary winding of the step-down transformer and rectifier, the voltage stabilizer being made on a composite transistor and a precision adjustable voltage reference source, the primary winding of the step-down transformer is connected to the input of the power supply through the first safety device connected in series, the first high-pass filter at the input of the power supply and the suppression device in input voltage surges, the secondary winding of the step-down transformer is connected to the input of the rectifier through a second safety device connected in series, the voltage surge suppression device on the secondary winding of the step-down transformer and a second high-frequency interference filter, and the output of the rectifier is connected to the outputs of the power supply through a third safety device connected in series suppression of emissions of the rectified ripple voltage, three-link filter p for smoothing ripple at the output of the rectifier and voltage regulator. 2. The power supply according to claim 1, characterized in that the first high-frequency interference filter at the input of the power supply and the input voltage emission suppression device are combined into a single unit containing resistors common to this device and filter. 3. The power supply according to claim 2, characterized in that the first high-frequency interference filter at the input of the power supply and the input voltage surge suppression device are multi-stage. 4. The power supply according to claim 1, characterized in that a Darlington transistor mounted on a metal radiator through a heat-conducting electrically insulating gasket is used as a composite voltage stabilizer transistor. 5. The power supply according to claim 1, characterized in that the voltage regulator is connected to the output of the power supply through the device to protect the output circuit from overload, short circuit and inadvertent connections of external power sources to it, including a fourth safety device. 6. The power source according to claim 1, characterized in that the step-down transformer is made on a toroidal core filled with a compound. 7. Power supply according to paragraphs. 1 and 5, characterized in that the safety devices are made in the form of fuses. 8. The power supply according to claim 1, characterized in that the primary winding of the transformer and the output of the power supply are made respectively with a voltage indicator of the network and with a voltage indicator at the output of the power source. 9. The power source according to claim 8, characterized in that the indicators are made on LEDs.

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