RU126248U1 - HEAVY DUTY LED POWER SUPPLY - Google Patents

Abstract

A power supply device for heavy-duty LEDs, which contains a series-connected line filter, a rectifier, a power factor corrector and a feedback resistor connected to a common bus, as well as a low-voltage power supply unit, a transformer, the primary winding of which is connected to the drains of two transistor switches, and its middle point is connected to the output of the power factor corrector block; inductor, the first terminals of the independent windings of which are connected respectively to the output ends of the first secondary winding, the middle terminal of which is connected to the first lining of the smoothing capacitor and the first output of the LED, the second terminal of which is connected to the second lining of the smoothing capacitor and the first terminals of rectifier diodes, the second conclusions of which are connected respectively to the second conclusions of the independent windings of the inductor; the outputs of the second secondary winding of the transformer are connected to the corresponding inputs of the low-voltage power supply, characterized in that it contains resistors, capacitors and a controller, moreover: the first capacitor is connected between two outputs of the rectifier, the first output of which is connected through the seventh resistor to the Vcc input of the controller and the first output of the low-voltage block nutrition; the second output of the rectifier is connected to the first terminals of the first and second resistors; the second output of the second resistor is connected to the first output of the second capacitor, the input of the controller IN2 + and through the fourth resistor to the input of the IN1 controller and the first output of the third resistor, the second output of which is connected to the input of the controller Vref and through the fifth resistor to the input of the IN2 controller and the first output of the sixth resistor; outputs O1

Description

The utility model relates to electronic devices of secondary power supply, in particular, to power sources of heavy-duty LEDs and can find application in energy-saving and environmental luminaires.

Known power supply devices for heavy-duty LEDs, based on the principle of transmitting current stored in the inductor on the reverse stroke - when the switching transistor is off [1]. Also known are power devices for heavy-duty LEDs with a single-stage cascade for lowering voltage for direct current [2], [3]. In these devices, power transistors participating in the formation of the current of a heavy-duty LED in accordance with the operation schedule are presented with increased requirements, since the power dissipated by the field-effect transistor is proportional to the square of the current flowing through it.

The closest to the claimed solution in technical essence is a fluorescent lamp power supply device [4], which contains a line filter, a rectifier, a power factor corrector, a low-voltage power supply unit, a switch, two transistor switches, a transformer, an inductor, an ignition capacitor, an OR element, a feedback resistor , one-shot, generator and protection unit with associated links.

However, the known technical solution has a significant drawback in that when changing the magnitude of the supply voltage and currents stored in the reactive elements, the cyclogram does not track the changing parameters, and a catastrophic failure occurs.

The technical task of the utility model is to increase the reliability of the power supply device for heavy-duty LEDs by reducing the magnitude of the switching currents of power transistors and turning them on at the moment of minimum voltage at the drains.

The problem is solved in that in a device containing a power supply filter, a rectifier, a power factor corrector, a low-voltage power supply unit, two transistor switches, a transformer, a inductor, a feedback resistor, a controller is introduced, with a strapping in the form of resistors and a capacitor, rectifier diodes and a smoothing capacitor with corresponding connections.

The essence of the utility model is illustrated by drawings, where:

- Figure 1 shows the structural diagram of the power supply device of high-power LEDs with an active corrector power factor.

- On. Figure 2 shows a structural diagram of a power supply device for heavy duty LEDs without an active corrector power factor.

- Figure 3 shows the structural diagram of the controller.

The device comprises: a network filter 1 (Fig. 1, 2), a rectifier 2, a power factor corrector 3 (Fig. 1) or a resistor 3R1 (Fig. 2), a controller 4 (Fig. 1, 2), a feedback resistor R1, a low-voltage unit power supply 5, transformer TP, switching transistors T1 and T2, as well as resistors R2 ... R7, capacitors C1 ... C3 and diodes D1, D2, which ensure the functioning of the circuit.

The main power supply functions of the LED are performed by the current generator based on the Push-Pull circuit (push-pull switching of the transformer winding with a midpoint).

Consider the operation of the oscillator in steady state. The current flowing in the primary circuit (I) of the transformer TP (Fig. 1, 2) is closed through an open transistor (T1), feedback resistor R1, and capacitor [5] 3C3 (Fig. 1) or capacitor C1 (Fig. 2) . This current increases in proportion to the secondary current (III or IV) of the transformer TP (Figs. 1, 2) flowing through the inductor DR1 and LED LED. Accordingly, a negative polarity voltage arises at the feedback resistor R1 relative to the COM output of controller 4, increasing to the threshold U- specified by resistors R2, R3, R4 and voltage Vref, after which controller 4 turns off both switching transistors (T1 and T2).

The threshold "U-" off transistors T1 and T2 is determined by the formula:

U - = (Vref / (R2 + R3 + R4)) * (R2 + R3).

The integrating circuit R2, C2 is designed to filter out interference arising from switching switching transistors T1 and T2

The current stored in the reactive elements (TP, DR1, C1) is discharged to the LED LED. In this case, the voltage at the feedback resistor R1 changes the polarity, forming in a positive polarity relative to the output of the COM controller 4, and then decreases to zero. When the voltage value of positive polarity exceeds the threshold specified by the resistors R5, R6 and voltage Vref, the transistor T2, closed in the previous switching cycle, is turned on. However, despite the open state of this transistor, the current in the circuit continues to flow in the opposite direction as the reactive elements are discharged, closing through the parallel counter diode of the transistor T2. After this current drops to zero, it changes direction and begins to increase through the open transistor T2. All processes are repeated.

Thus, the current amplitude of the LED Im (LED) depends on the threshold U- at which the switching transistors T1 and T2 are turned off, the resistance of the feedback resistor R1 and the ratio of the turns of the primary and secondary windings of the transformer TR:

Im (LED) = (U- / R1) * (N (I) / N (III)), where N (I), N (III) is the number of turns of the windings I and II.

The switching frequency for the given windings of the transformer TP and the threshold U- depends on the magnitude of the inductance of the inductor DR1 and the voltage of the power bus at the midpoint of the switched windings of the transformer TP.

In a device without an active power factor corrector (Fig. 2), the power rail at the midpoint of the switched windings, the transformer TP is a rectified and not smoothed capacitor C1 network voltage. This voltage without smoothed dips between half-waves is fed through resistor 3R1 to input IN1 - thereby forming a threshold depending on the sinusoidal voltage of the mains supply.

The controller (Figure 3) includes: three comparators Comp1, Comp2, Сomp3, RS trigger 4M1, counting trigger 4M2, elements OR 4M2, 4M3, NOR elements with output power amplifiers 4M5, 4M6, resistors 4R1 ... 4R6, 4T1 transistor and ZD1 zener diode .

The comp3 comparator, resistors 4R1 ... 4R4 and transistor 4T1 are designed to supply low-voltage power to the elements of the controller circuit. The voltage at the terminal Vcc increases as the capacitance 5C2 (Fig. 1, 2) is charged from the high voltage bus through the resistor R7. When the magnitude of this voltage forms at the "positive" input of the comparator Comp3 (Figure 3) the voltage U is greater than the voltage on the zener diode ZD1 (U _ZD1 ), the transistor 4T1 will open and the voltage Vcc will go to the controller circuit. Further, the controller power will be supported from the winding V of the transformer TP (Figs. 1, 2) through the low-voltage power supply 5.

U = Vcc / (4R2 + 4R3 * 4R4 / (4R3 + 4R4))

Comparator Comp1 (Figure 3) is designed to turn off the power transistors T1, T2 (Figure 1, 2) through the outputs 01, 02 (Figure 3) and switch the counting trigger 4M2. At the same time, outputs 01 and 02 remain in a low state in three cases:

1) power to the controller elements is not supplied, and the low level is supported by resistors 4R5, 4R6 connected to the COM bus;

2) the comparator Comp1 switched to a high state due to exceeding the threshold by the current flowing through the resistor R1 (Fig.1, 2). Next, a high level comparator Comp1 (Figure 3) is inverted by the elements M5, M6 - NOR and at the outputs 01 and 02 a low level is formed that closes the transistors T1 and T2 (Figure 1, 2);

3) RS trigger 4M1 (Figure 3) with a pulse from the output, the comparator Comp1 is set to high state at the output Q, which is transmitted through the elements 4M3, 4M4 (OR) and inverted by the elements 4M5, 4M6 (NOR). At the outputs 01 and 02, a low level is formed, closing the transistors T1 and T2 (Fig.1, 2).

Comparator Comp2 (Figure 3) is designed to turn on one of the two power transistors through outputs 01, 02 after exceeding the threshold level U + on the comparator Comp2.

The threshold level U + is set by resistors R5, R6 (Fig.1, 2):

U + = (Vref / (R5 + R6)) * R6.

The U + level does not affect the LED current and the switching frequency of transistors T1 and T2, but affects the level of noise immunity of the device to impulse noise.

Information sources:

1. Datasheets HV9910

2. Datasheets MBI6901, MBI6902

3. Datasheets TPS42011

4. Patent BY 6572 C1 Int.cl. H05B 41/16 12/30/2004

5. Datasheets MC34262

Claims (1)

A power supply device for heavy-duty LEDs, which contains a series-connected line filter, a rectifier, a power factor corrector and a feedback resistor connected to a common bus, as well as a low-voltage power supply unit, a transformer, the primary winding of which is connected to the drains of two transistor switches, and its middle point is connected to the output of the power factor corrector block; inductor, the first terminals of the independent windings of which are connected respectively to the output ends of the first secondary winding, the middle terminal of which is connected to the first lining of the smoothing capacitor and the first output of the LED, the second terminal of which is connected to the second lining of the smoothing capacitor and the first terminals of rectifier diodes, the second conclusions of which are connected respectively to the second conclusions of the independent windings of the inductor; the outputs of the second secondary winding of the transformer are connected to the corresponding inputs of the low-voltage power supply, characterized in that it contains resistors, capacitors and a controller, moreover: the first capacitor is connected between two outputs of the rectifier, the first output of which is connected through the seventh resistor to the Vcc input of the controller and the first output of the low-voltage block nutrition; the second output of the rectifier is connected to the first terminals of the first and second resistors; the second output of the second resistor is connected to the first output of the second capacitor, the input of the controller IN2 + and through the fourth resistor to the input of the IN1 controller and the first output of the third resistor, the second output of which is connected to the input of the controller Vref and through the fifth resistor to the input of the IN2 controller and the first output of the sixth resistor; the outputs O1 and O2 of the controller are connected respectively to the gates of the transistor switches; second terminals of the first resistor, second capacitor, sixth resistor, low-voltage power supply, terminals IN1 + and COM controller, the sources of transistor switches are connected by a common bus.

Images