ITBA20120075A1 - POWER SUPPLY AND DRIVER FOR ROAD LED ILLUMINATOR WITH VARIABLE CAPACITIVE REACTANCE - Google Patents

Description

DESCRIPTION

Of the Industrial Invention entitled:

POWER SUPPLY AND DRIVER FOR LED STREET LIGHT WITH VARIABLE CAPACITIVE REACTANCE

BACKGROUND OF THE TECHNIQUE:

Definitions: A street LED illuminator is a street lighting apparatus with a total power of the minimum LED matrix of 38W, consisting of the street fixture, the LED matrix and the power supply.

of the Power (energy consumption) expressed in W / hour.

Ampere: Current unit of measurement.

Given that the LEDs operate with a variable voltage from 2.9 V to 3.6 V. The complexity in the use of high brightness LEDs translates into the consistent variability of absorption as a function of very small voltage variations. This criticality forces the designers of LED power supplies to have to add to the classic power supply section, a section of drivers capable of controlling and limiting the current flowing in the circuit. Considering the standard operating voltage of the LEDs and the simplicity of construction of the driver capable of controlling the current with low voltage, the manufacturers of power supplies and LED drivers make the power supply unit in two sections: the first for power supply and transformation of the 220V AC low voltage DC voltage (see TABLE Λ POWER SUPPLY) and the second current control section of the circuit with consequent further reduction of the voltage to keep the current stable (See TABLE A CURRENT LIMITER DRIVER).

This constructive conception obliges the designers to use lamellar or toroidal transformers to transform the initial 22 OV AC voltage into low DC voltage. In consideration of the fact that all transformers exploit a double conversion in the electromagnetic field, it is part of the obligatory path to lose from 10% to 15% of efficiency. Furthermore, the switching in PWM (power with modulation) of the power transistors dissipates another quantity of electrical energy estimated between 3% to 7%. In conclusion, the loss of efficiency and the consequent dissipated energy consumption can be delineated, measurable in total from 15% to 20% depending on the technique and technology adopted.

OBJECTIVE THAT INNOVATION INTENDS TO REACH:

The adoption of LED lighting technology allows in itself to have greater efficiency than traditional technologies with effective savings ranging from 35% compared to technologies defined as gas discharge (SAP, mercury, metal halides) up to 80% compared to to old light bulbs with tungsten filament. The objectives of the patents are the adoption of a technology on the LED street power supply that allows to accentuate the actual energy saving, using a completely innovative technique on the power supply section capable of almost completely eliminating the energy dissipated by the components of the section. power supply and current control driver.

Let us consider the diagram of a typical power supply Table A) voltage reducer where the initial voltage of 220 V AC passes through the transformer, which with a double conversion from electric voltage into electromagnetic field and from electromagnetic field into electric voltage, reduces the voltage from the nominal 220V AC to, for example 24 V AG, then the rectifier diode, overturns the negative half-wave of the alternating voltage into the same positive half-wave, then into DC voltage and further leveled by the electrolytic capacitor.

The patent's own technology. consists in removing from the power supply section, the transformer and the current control section, with a high frequency switching circuit, exploiting the physical principle of the capacitive reactance of the capacitors.

Remembering that, a capacitor (usually indicated with C), is generally made up of a pair of conductors (plates or plates} separated by an insulator (dielectric). The charge is stored on the surface of the plates, on the edge in contact with the dielectric. Therefore on the outside there will be an electric field equal to zero due to the two fields, one positive and one negative, which have precisely the same module but opposite sign (towards), while inside the device twice the electric field because both fields, both the positive and the negative, have the same module and the same direction.The electrostatic energy that the capacitor accumulates is localized in the dielectric material that is interposed between the plates.

In an alternating current (AC) voltage regime, on the other hand, this induces variations in potential at which the plates are charged and discharged by electrostatic induction, generating a variable current at its ends (at the same frequency as the excitation) which then circulates circuit.

Starting from the report:

getting

The relationship between the voltage and the current across the capacitor holds, and it is observed that the alternating voltage phase out the current by -90 degrees. Expressing the ratio in polar form, the expression of the characteristic impedance of the device is obtained;

which by applying Euler's formula becomes:

where f is the frequency of the AC measured in hertz and C the capacitance, measured in Farads.

Unless parasitic dissipation phenomena, however present in real cases, the ideal capacitor therefore has a purely imaginary impedance equal to its reactance, indicating with it its ability to store electrical energy.

In Ohm's law in symbolic form, the fascinal operator is also considered:

where Xc is the capacitive reactance, measured in Ohm which can be considered as analogous to a kind of resistance that the capacitor opposes to the current and depends on the frequency of the AC. It is also noted that:

■ Reactance is inversely proportional to frequency. This confirms what was said above and that is when we are in the presence of a DC power supply we have zero frequencies (f = 0); this leads to theoretically infinite reactance values. An infinite reactance can be seen as an open switch that does not circulate current;

A At high frequencies the reactance is so small that it can be safely overlooked when making calculations.

The reactance is so called because the capacitor does not dissipate power but simply accumulates energy and then releases it in the final transient. In electrical circuits, as in mechanics; the capacitor constitutes a load and reactive, since it stores the energy and releases it in the end, thus "reacting" to the voltage variations in the circuit.

It is also significant that impedance is inversely proportional to capacitance, unlike resistors and inductors where impedances are linearly proportional to resistance and indutance respectively.

Therefore, reiterating that a capacitor in a serial circuit in alternating current, behaves in the same way as a resistance with the difference that it does not dissipate any current and at the same time, with the formulas indicated above, it is possible to limit the current flowing in the circuit by appropriately dimensioning the capacitor values, it will be possible to obtain a circuit with double functionality; of transformerless voltage reducer and current controller flowing in the circuit.

Therefore the basic circuit of the power supply and LED driver will now be in Table B) in which the transformer and the limiting stage for running in low voltage have been eliminated. Following the electronic diagram, the 220V AC input alternating voltage crosses the capacitance connected in series which will behave as a common electrical resistance opposing the reactance to limit the amount of current flowing in the circuit. After the diode bridge which rectifies the alternating voltage, the smoothing capacitor further levels the voltage to avoid visible flickering of the luminous flux emitted by the LEDs, and at the tail the LED matrix circuit,

By recalculating the reactor values with the formulas indicated above, based on the parameters of the mains voltage within the minimum and maximum limits allowed for the mains voltage of the electricity supplier, from 195V AC to 260AC (- 15% of the nominal voltage), the result is very different values of the capacity must be adopted.

Therefore, the basic circuit of A with capacitive reactance must be equipped with another circuit capable of monitoring the mains voltage and varying the capacitive reactance of the serial circuit, adding or subtracting from the base capacitor, in parallel as many capacitors able to compensate for the variations of voltage to return to the desired current range to slide in the circuit (see Table B electronic circuit for reactance control and variation), using transistors or Triacs or Scr or relays capable of hooking up capacitors to the serial circuit in parallel to the applied base capacitor , creating a power supply and driver for LEDs with variable capacitive reactance. It is obvious that this reasoning is valid only and exclusively in the condition in which the load is always constant.

DLL ANALYSIS RESULT ACHIEVED:

The analysis of the result of an LED street light power supply with variable capacitive reactance technology is measurable by measuring the difference in electrical consumption in W / hour of the total LED system, by measuring the total consumption of the LED matrix separately, obtained by multiplying the voltage for the current of the LED matrix, and subtracting the consumption of the LED matrix from the total consumption, the consumption in W / hour of the power supply section will be obtained.

For example, if the total system consumption of a 100 W LEDs of 1 W each measured is 120 W and if we measure the consumption of the LED matrix in 100W, we will have that the difference between 120 W of the system and the 100W of the matrix LED, i.e. 20 W is the consumption in W / hour dissipated by the power supply (see table C),

By adopting the variable capacitive reactance technology, as the construction technology of a power supply for street lighting with LED technology, we will have the system consumption of the illuminator equal to 100.7W the consumption of the LED matrix will be 100W, the difference obtained shows the actual consumption of the power supply which is only 0.7W, a value close to 0

(see Table C).

The adoption of this technology saves the 15% / 20% that traditional power supplies - drivers for LEDs dissipate, consequently increasing the overall efficiency of an LED street light.

Claims (1)

CLAIMS The exclusive use of the different technology for LED power supply-driver is claimed, on LED street light with power greater than 38 W overall based on transformerless technology capable of varying the capacitive reactance with a special electronic circuit, switching via electronic components such as transistors or triacs or Scr or relays or other electronic or mechanical or electromechanical devices. The new driver-power supply technology for LED street lights must not use lamellar or toroidal transformers but must limit the current in the circuit causing an output voltage drop depending on the value of the capacitor connected in series to the initial 220V AC voltage.