EP4362608A1

EP4362608A1 - Energy saving power supply device

Info

Publication number: EP4362608A1
Application number: EP22425051.4A
Authority: EP
Inventors: Pietro Montalto
Original assignee: Individual
Current assignee: Individual
Priority date: 2022-10-24
Filing date: 2022-10-24
Publication date: 2024-05-01

Abstract

The present invention relates to a power supply device (1) for a resistive inductive load (30) characterised in that it comprises an electrical generator (20) able to generate a radio frequency electromagnetic wave and a logic control unit that can be coupled to said resistive inductive load. The logic control unit (U) is adapted to perform (120) a frequency scan to determine a specific resonance frequency for said resistive inductive load (30), and to send (140) a command to said electrical generator (20) to power said resistive inductive load (30) with an electromagnetic wave at said specific resonance frequency for said resistive inductive load (30).

Furthermore, the present invention also relates to a heating system (R), a method (100) for operating said power supply device, its use and an Internet of Things computer network.

Description

The present invention relates to an energy saving power supply device.
In particular, an object of the present invention is a device using the emission of radio frequency electromagnetic waves to power resistive loads and achieve energy savings.
The present invention also relates to a heating system for an oven comprising said power supply device and a resistive inductive load.
The present invention also relates to the method for operating said power supply device and the use of said power supply device to power a heating element of an oven.
Finally, the present invention relates to an Internet of Things computer network.

Prior Art

As is known, there are various types of gas or electricity powered heating systems. In recent years, in order to face the global challenge of climate change, a greater number of appliances are powered by the power distribution grid.
In particular, by way of example for heating an oven, electrical devices are used wherein the heating takes place by using the heat dissipation from a resistance through the Joule effect. However, the efficiency of such devices is not very high. In fact, the power efficiency of such devices is just over 20%, i.e. only 20% of the electrical power used is transformed into the desired heating effect.
In particular, it is known that the heating of a resistance due to the Joule effect is due to the collision of the electrical charges, i.e. the electrons of the current flowing in said resistance, with the atoms of the resistive material. The number of impacts and the consequent bond breaking produce an emission of heat which represents the heating effect of the resistance. It is therefore a phenomenon of opposition to the current flow, i.e. an undesirable effect when compared to the normal applications of resistors.
Furthermore, the impediment to the current flow depends on the resistivity of said resistor, whose value depends on a temperature coefficient, according to the following relationship: $ρ_{T} = ρ_{0} (1 + α_{0} T)$
Wherein ρ_T is the resistivity at the temperature T of the resistor, ρ ₀ is the resistivity at the temperature of 0°C, α ₀ is the temperature coefficient at 0°C and T is the temperature value. Furthermore, the electrical power, expressed in Watts and applied to a resistor, can be calculated from the following relationship P = RI ², wherein I is the current flowing in the resistor and R is the resistance.
In particular, to measure the phenomenon deriving from the Joule effect, it is necessary to refer to the Joule or cal/s measurement unit, since the calorie is the amount of heat necessary to increase the temperature of 1 g of distilled water by 1°C (precisely from 14.5°C to 15,5°C). Since 0.239 cal corresponds to 1 J, it is possible to obtain the relationship that leads to the aforementioned efficiency, obtaining the equivalent thermal power, i.e. the thermal power dissipated by the resistor due to the thermal effect: $P_{TR} = {RI}^{2} * 0,239$
Furthermore, the value that can be used to measure a resistor, i.e. its resistance, depends on the following relationship R = ρL/S wherein ρ is the resistivity, L is the length and S the section.
On the basis of the above relationships, it can be seen that the power efficiency can be increased by selecting a resistor of adequate size and with a temperature coefficient as high as possible. Furthermore, the resistivity and therefore the efficiency depend on the temperature behavior of the selected resistive material.
However, to date it is not possible to greatly increase the efficiency according to the resistivity and conductivity of the best known materials of this type. Furthermore, it is necessary to also consider the ability to maintain the characteristics of the material, subjected to a high heating, within sufficiently stable parameters. In fact, the higher the resistivity value, the greater the resistance variation, up to its breaking limit. It is also necessary to consider that the resistivity is typical of the material, therefore, it is easy to deduce that there is a limit of heat dissipation beyond which, by increasing the electrical power used, the efficiency tends to decrease. Therefore, it is necessary to find a compromise between the size of the resistor and the type of material used, for the same electrical power used.
Furthermore, in said devices the energy consumption is heavy, since rather high values of current are required to raise the temperature in question. In fact, the resistance is subjected to a non-negligible mechanical stress and this leads to a significant deterioration of performance and lifespan of the resistance itself. Due to this drawback the performance of the system is compromised, as well as the input/output characteristics. In fact, by varying the mechanical and physical properties of the heating device, also the modalities used by this device for releasing heat vary, so that the control of the temperature to be heated will be inaccurate. This causes issues in all applications where a high accuracy of the working temperature is required.
Therefore, in the specific sector, there is a need to increase the efficiency of electrical heating devices that use electrical resistances as heating element.

Aim of the innovation

This need is satisfied by the device according to the present invention which also offers further advantages which will become clear in the following.
Therefore, an aim of the present invention is to provide a power supply device, which produces energy savings when connected to a resistive load such as for example a heating element of a three-phase industrial oven.
A further aim of the invention is to provide a power supply device that also makes it possible to overcome the limits of the heating devices of known technology and to obtain the technical results described later.
A further aim of the invention is to offer a control on the device, so as to intervene in real time, to optimise the output of the radio frequency generator, in such a way as to detect a specific resonance frequency depending on the resistive inductive load applied to the heating system.

Object of the invention

Therefore, it is a specific object of the present invention a power supply device as defined in claim 1, a method for operating a power supply device as defined in claim 13 and the use of the heating device as defined in claim 15.
Preferred embodiments are defined in the dependent claims.

List of the attached figures

The present invention will now be described, for illustrative but not limitative purposes, according to a preferred embodiment thereof, with particular reference to the figures of the attached drawings, wherein:

Figure 1 shows a schematic view of an embodiment of a power supply device according to the present invention;
Figure 2 shows a block diagram of a method for operating the device of Figure 1.

Detailed description of the innovation

Hereinafter, the description will be focused on an electrical device for powering an electrical resistance of an oven but it is very clear that it should not be considered limited to this specific use. For example, the use of the described system can also be aimed at the heating of domestic environments, or at the industrial world where devices using electrical resistances are very energy-consuming and contribute in a sustained way to overload the plants distributing electrical power.
Referring to Figure 1, an embodiment of a power supply device according to the present invention is now described.
In particular, with reference to Figure 1, a heating system R is shown comprising a power supply device 1 and a resistive inductive load 30.
The resistive inductive load 30 is electrically coupled to the power supply device 1 and produces heat when powered by said power supply device 1 at a specific resonance frequency for said resistive inductive load 30.
There is only one specific resonance frequency depending on the material of the resistive inductive load 30, which determines the increase of the thermal efficiency and therefore the minimum absorption of current by the powered resistive inductive load 30.
The resistive inductive load 30 can be made of a material having inductive-capacitive properties, such as for example constantan, manganin, nichrome or another material. These materials have a high thermal efficiency when powered by an alternating current (AC) power grid with a nominal 50 Hertz frequency.
In particular, constantan has the property of keeping its resistivity almost unchanged as the temperature varies. Manganin has a low coefficient of variation of resistivity as the temperature varies and is an alloy that is easy to draw but does not easily oxidise.
The resistive inductive load 30 can be, for example, a commonly used commercial resistance, normally powered by a 220 volt power grid or, in case of 380 volt three-phase appliances, by a 380 volt power grid.
With reference to Figure 1, the power supply device 1 comprises an electrical generator 20 which can be electrically coupled to said resistive inductive load 30 and is adapted to generate a radio frequency electromagnetic wave.
In particular, by using an electromagnetic wave generated by the power supply device 1 at the resonance frequency of the resistive inductive load 30, there is a reduction of the current flowing through the resistive inductive load 30 and consequently a reduction of the mechanical stress to which said resistive inductive load 30 is subjected. The load will therefore be considered as an electrical dipole, in order to be able to use the reactive-capacitive part to resonate the resistive inductive load 30 in order to obtain energy savings.
Therefore, by reducing the mechanical stress to which said resistive inductive load 30 is subjected, the characteristic parameters of the resistive inductive load 30 remain almost constant. In addition, by using an electromagnetic wave generated by the power supply device 1 it is possible to vary the temperature more quickly, this solution is therefore applicable to systems requiring rather short response times.
The electrical generator 20 can be powered by the power grid. For example, in the case of 380 volt three-phase appliances, three 19-inch rack power units can be used, in a star configuration without a central reference or in a delta configuration, with modules suitable for the maximum absorption of the power grid to power the power supply device. 1. In this way it is possible to obtain a stabilised voltage on the 380 volt three-phase.
The electrical generator 20 can therefore be used as a power source for a heating element of an oven such as for example the resistive inductive load 30 of an electrical heating system R described above.
The power supply device 1 further comprises a logic control unit U. The logic control unit U may comprise for example a voltage controlled oscillator (VCO) circuit comprising a control signal generation circuit and a Mosfet Gate Driver with dedicated integrated circuits.
The logic control unit U is adapted to perform 120 a frequency scan to determine a specific resonance frequency for said resistive inductive load 30, and to send 140 a command to said electrical generator 20 to power said resistive inductive load 30 with an electromagnetic wave at said specific resonance frequency for said resistive inductive load 30 as shown in the block diagram of the operating method in Figure 2.
The operating method described above therefore makes it possible to offer a current-controlled proportional feedback. Said feedback makes it possible to optimise the input-output parameters of the closed loop control system (P.I.D.) and to vary the frequency of the radio frequency generator 20 through for example a voltage-controlled oscillator circuit.
In particular, the feedback system identifies the resonance frequency of the resistive inductive load 30 through a real-time control carried out by an algorithm which is performed by a processor. For example, 32-bit microcontrollers with high clock frequencies and implementing digital signal processing algorithms, such as P.I.D. systems, can be used. Said P.I.D. systems can process system variations in real time to stabilise the input-output system.
With reference to the power supply device 1, said radio frequency electromagnetic wave can be an asymmetrical square wave and can have a frequency of about 3 kHz, tuned to said specific resonance frequency for said resistive inductive load 30.
The power supply device 1 may also include a band filter (not shown in the figure) with a high merit factor in order to reduce the harmonic components of the radio frequency electromagnetic wave at the output of the power supply device 1.
The power supply device 1 may further comprise one or more metal panels 40 for shielding said resistive inductive load 30 and/or said electrical generator 20 from both induced and conducted electromagnetic emissions.
The presence of said metal panels 40 allows the power supply device 1 to have an electromagnetic compatibility and to be considered a commercial product to be placed on the markets that complies with the European standards on the maximum emissions permitted by the directives in force.
For example, said power supply device 1 may comprise EMI shields and cables equipped with ferrite rings. For example, said power supply device 1 can be assembled on a professional frame in an industrial standard 19" rack format strictly shielded with aluminum supporting structures and EMI shields.
Furthermore, the power supply device 1 may include high-insulating photo couplers to protect the user from any electrical discharge caused by malfunction and/or breakdown of the machine in the high voltage area.
The power supply device 1 can further comprise one or more protection circuits 50 electrically coupled to said one or more metal panels 40 and/or to said logic control unit U.
Said protection circuits 50 comprise a sensor (not shown in the figure) adapted to detect a physical parameter associated with said one or more metal panels 40 and to communicate said physical parameter to said logic control unit U. The logic control unit U is able to read said physical parameter, and activate an alarm if said physical parameter reaches a threshold value.
The protection circuits 50 can also be coupled to said resistive inductive load 30 and may comprise a further sensor (not shown in the figure). Said sensor can be configured to detect a further physical parameter associated with said resistive inductive load 30. The physical parameter detected by the sensor can be communicated to the logic control unit U which is configured to read said further physical parameter, and activate said alarm if said further physical parameter reaches a further threshold value.
With reference to said protection circuits 50, the sensors described above may comprise a temperature sensor, a voltage sensor, a vibrational sensor, and/or an accelerometer. For example, the sensors may comprise one or more temperature sensors able to detect a temperature value of said one or more metal panels 40, and/or a temperature value of said resistive inductive load 30.
The sensors may comprise a voltage sensor which detects a voltage value of said resistive inductive load 30. Additionally or alternatively, the sensors may comprise a vibrational sensor or an accelerometer for detecting an action of tampering with said power supply device 1.
The power supply device 1 shown in Figure 1 may further comprise a power circuit 70 electrically connected to said electrical generator 20 for regulating the voltage at the output of said electric generator 20. Said power circuits may comprise at least one cooling system, for example with radiators made of black anodized aluminum and suitably cooled by low-noise fans. In particular, in case of single-phase systems, said power supply device 1 may comprise a power circuit 70 for regulating the output voltage, the maximum current and the power, with the aid of SCR diodes which control the duty cycle of the square wave at the output of the power supply device 1 and ensure that the resistive inductive load 30 is powered at its stabilised 220 volt rated voltage.
The power supply device 1 may further comprise a switchgear 60 adapted to permute the electrical coupling between said resistive inductive load 30 and said electrical generator 20 and a further switchgear (not shown in the figure) for permuting the electrical coupling between said resistive inductive load 30 and said power grid.
By permuting the electrical coupling between the resistive load and the respective power supply, the logic control unit U can determine a first electrical absorption value when said resistive inductive load 30 is powered by the power grid and a second electrical absorption value when said resistive inductive load 30 is powered by said electrical generator. These absorption values can be compared later by the logic control unit U to determine an electricity saving value obtained using the power supply of the power supply device 1.
The power supply device 1 described above can be an integral part of an Internet of Things (IoT) computer network. The computer network may therefore comprise at least one power supply device 1 as described with reference to Figure 1.
Said power supply devices 1 may therefore include a communication module (not shown in the figure) coupled to said logic control unit U and adapted to receive/transmit one or more control signals to control and/or check the operation of said at least one power supply device 1.
The communication module may be communicatively coupled to a communication interface configured to receive/transmit said one or more control signals from/to said at least one communication module. The communication interface may be part of a remote server or remote device that allows the remote control of the device.
Said communication interface may be coupled to display means, such as for example a display or monitor, configured to present said one or more control signals to an operator/user so as to remotely control the parameters of the power supply device 1 or of the heating system R.
In this way, the end operator or end user can remotely control the energy saving system and from his/her smartphone or tablet can check both the electrical parameters and the actual energy savings obtained by the system.
The parameters may include at least one of an instantaneous voltage, a minimum and maximum voltage, current, the resonance frequency, the active power, the reactive power, a grounding control, a ground-current differential-voltage neutral-ground-temperature resistance, energy savings, the consumption estimate, the cost estimate, the instant, daily, weekly and monthly consumption, the estimate of carbon dioxide present in the environment.
The communication interface is also able to display an alert message to warn that the instrument has been tampered with.
Advantageously, by means of the power supply device, object of the invention, it is possible to produce energy savings when it is connected to a resistive load, such as for example a heating element of a three-phase industrial oven.
A second advantage is that said power supply device also makes it possible to overcome the limits of the heating devices of known technology and to obtain the technical results described above.
A further advantage is that the method for operating said power supply device offers a control on said device, so as to intervene in real time, to optimise the output of the radio frequency generator, in such a way as to detect a specific resonance frequency according to the resistive inductive load applied to the heating system.
The present invention has been described for illustrative, but not limitative purposes, according to its preferred embodiments, but it is understood that variations and/or modifications may be made by those skilled in the art without thereby departing from its scope of protection, as defined by the attached claims.

Claims

A power supply device (1) for a resistive inductive load (30) characterised in that it comprises:
- an electrical generator (20) adapted to generate a radio frequency electromagnetic wave, wherein said electrical generator (20) can be electrically coupled to said resistive inductive load (30); and

- a logic control unit (U) adapted to:
perform (120) a frequency scan to determine a specific resonance frequency for said resistive inductive load (30), and

send (140) a command to said electrical generator (20) to power said resistive inductive load (30) with an electromagnetic wave at said specific resonance frequency for said resistive inductive load (30).
The power supply device (1) according to claim 1, further comprising one or more metal panels (40) for shielding said resistive inductive load (30) and/or said electrical generator (20) from electromagnetic emissions.
The power supply device (1) according to claim 1 or 2, characterised in that said radio frequency electromagnetic wave has a frequency of about 3 kHz, tuned to said specific resonance frequency for said resistive inductive load (30), and preferably wherein said electromagnetic wave is an asymmetrical square wave.
The power supply device (1) according to claim 2 or 3, characterised in that it comprises one or more protection circuits (50) electrically coupled to said one or more metal panels (40) and to said logic control unit (U),
wherein said one or more protection circuits (50) comprise at least one sensor adapted to detect a physical parameter associated with said one or more metal panels (40) and to communicate said physical parameter to said logic control unit (U), and

wherein said logic control unit (U) is configured to read said physical parameter, and activate an alarm if said physical parameter reaches a threshold value.
The power supply device (1) according to claim 4, wherein said one or more protection circuits (50) can be coupled to said resistive inductive load (30) and wherein said at least one sensor is configured to detect a further physical parameter associated with said resistive inductive load (30) and to communicate said further physical parameter to said logic control unit (U), and
wherein said logic control unit (U) is configured to read said further physical parameter, and activate said alarm if said further physical parameter reaches a further threshold value.
The power supply device (1) according to claim 4 or 5, characterised in that said at least one sensor comprises a temperature sensor and said physical parameter comprises a temperature value of said one or more metal panels (40), and/or said further physical parameter comprises a temperature value of said resistive inductive load (30).
The power supply device (1) according to claim 5, characterised in that said at least one sensor comprises a voltage sensor and said at least one physical parameter comprises a voltage value of said resistive inductive load (30).
The power supply device (1) according to any one of claims 4-7, characterised in that said at least one sensor comprises a vibrational sensor or an accelerometer to detect an action of tampering with said power supply device (1).
The power supply device (1) according to any one of the preceding claims, characterised in that it comprises a power circuit (70) electrically connected to said electrical generator (20) for regulating the voltage at the output of said electric generator (20).
The power supply device (1) according to any one of the preceding claims, wherein said electrical generator (20) is powered by the power grid and wherein said power supply device (1) is characterised in that it comprises at least one switchgear (60) adapted to
permute the electrical coupling between said resistive inductive load (30) and said electrical generator (20); and

permute the electrical coupling between said resistive inductive load (30) and said power grid;
and wherein said logic control unit (U) is adapted to:
determine a first electrical absorption value when said resistive inductive load (30) is powered by a power grid;

determine a second electrical absorption value when said resistive inductive load (30) is powered by said electrical generator; and

determine an electrical saving value on the basis of a comparison between said first electrical absorption value and said second electrical absorption value.
A heating system (R) for an oven characterised in that it comprises:
a power supply device (1) according to any one of the preceding claims; and

a resistive inductive load (30) electrically coupled to said power supply device (1) and adapted to produce heat when powered by said power supply device (1) at a specific resonance frequency for said resistive inductive load (30).
The heating system (R) according to claim 11, characterised in that said resistive inductive load (30) is made of a material having inductive-capacitive properties, and preferably wherein said resistive inductive load (30) is made of constantan, manganin or nichrome.
A method (100) using a logic control unit (U) for operating a power supply device (1) according to any one of claims 1-10, comprising the following steps:
- performing (120) a frequency scan to determine a specific resonance frequency for said resistive inductive load (30), and

- sending (140) a command to the electrical generator (20) to power said resistive inductive load (30) electrically coupled to said generator with an electromagnetic wave at said specific resonance frequency for said resistive inductive load (30).
An Internet of Things (IoT) computer network, including:
at least one power supply device (1) according to any one of claims 1-10, wherein the logic control unit (U) of said at least one power supply device (1), comprises a communication module adapted to receive/transmit one or more control signals to control and/or check the operation of said at least one power supply device; and

a communication interface configured to receive/transmit said one or more control signals from/to said at least one communication module; and

one or more display means coupled to said communication interface and configured to present said one or more control signals.
Use of a power supply device (1) according to any one of claims 1-10 as a power supply for a heating element of an oven or a resistance inductive load of an electrical heating system (30).