RU119186U1 - PULSE LED POWER SUPPLY - Google Patents

Abstract

A switching power supply for LEDs comprising a primary rectifying smoothing means for receiving an alternating voltage current, generating a rectified smooth voltage and supplying this rectified smooth voltage as an input DC voltage to an isolation transformer included to transfer the output energy of the primary side to the secondary side, a damper unit connected in parallel with the primary winding of the transformer, a pulse generator, the output of which is connected to the gate of the power switch and is designed to interrupt the input DC voltage to maintain constant power in the load, an auxiliary rectifier with a linear voltage stabilizer connected between the isolation transformer and the pulse generator, rectifying smoothing secondary circuit means connected to the load and through the galvanic isolation element to the pulse generator, characterized in that the rectifying smoothing with the primary circuit contains a fuse, a noise suppression capacitor, a limiting resistor, a rectifier diode bridge, which is connected through low-loss filter capacitors, a choke and a low-loss filter capacitor to the primary winding of the isolation transformer, and the rectifying smoothing means of the secondary circuit contains a rectifier diode, and a group Low-loss smoothing capacitors connected in parallel, connected to the load through the choke of the protective device, and the isolation transformer contains an additional secondary �

Description

The utility model relates to the field of electronics, namely to the power sources (drivers) of high-power LEDs.

A known power source for LEDs containing a line filter, two inputs of which are connected to the power supply, and two outputs are connected to the corresponding inputs of the rectifier, the negative output of which is connected to the common input of the PWM controller and to the common output of the optocoupler, the positive output of the rectifier is connected to the capacitor electrode, to the electrodes of the first and second resistors, to the common input of the optocoupler and through the inductor to the drain of the power transistor and to the diode anode, the cathode of which is connected to another capacitor electrode, to the cathode a zener diode and through “n” series-connected LEDs with another electrode of the second resistor, another electrode of the first resistor is connected to the zener diode anode, another optocoupler output is connected to the PWM control input of the controller, the output of which is connected to the gate of the power transistor, the third resistor. A power factor corrector (PFC) was used as a PWM controller, a voltage sensor, a temperature sensor, a multiplier and a control unit were also introduced, the negative output of the rectifier connected to the input of the voltage sensor and the electrode of the third resistor, the positive output of the rectifier connected to another input of the voltage sensor, to the KKM power input, to the common inputs of the temperature sensor, control unit and multiplier, the output of the voltage sensor is connected to the KKM input, another electrode of the third resistor is connected to the input of the image communication through the current of the CMC and to the source of the power transistor, the zener diode cathode is connected to the input of the multiplier, the zener diode anode is connected to the first input of the control unit, the second input of which is connected to the output of the temperature sensor, the third input is connected to other electrodes of the second resistor and to the other input of the multiplier, the output of which is connected to the fourth input of the control unit, the output of which is connected to another input of the optocoupler (see RF patent for the invention No. 2385553, H05B 33/02, priority 16.11.2007)

The disadvantage of this source is the lack of galvanic isolation between the mains and the load, as well as the limited number of LEDs for connection.

Known switching power supply for high-power LEDs, built on the basis of a flyback converter with PWM regulation, containing a line filter, a rectifier, a smoothing capacitor, an isolation transformer included to transmit the output energy of the primary side to the secondary side, a damper assembly connected in parallel with the primary winding of the isolation transformer, pulse generator, the output of which is connected to the gate of the power switch and designed to interrupt the input DC voltage to maintain constant power in the load. The rectifying smoothing means of the secondary circuit is connected to the load and, through feedback control circuits, controls the stabilization of the current on the LEDs. (Dmitry Makashov. Flyback converter page 1 of 46 ,. monitor.espec.ws/download.php?id=80938, p. 12, Fig. 8

The disadvantages of this device is the low cos f, which leads to large loads on the supply network, as well as the need to use electrolytic capacitors in the smoothing circuits, which leads to a decrease in the service life of the device, as well as to limiting the input voltage.

The operation of the power switch in hard mode leads to a decrease in overall efficiency and intensive noise generation, which requires additional measures for their filtering.

The closest in technical essence to the claimed invention is a power source for high-power LEDs, which contains a line filter, a rectifier, a smoothing capacitor, an isolation transformer included to transmit the output energy of the primary side to the secondary side. The damper assembly is connected in parallel with the primary winding of the transformer. The output of the pulse generator is connected to the gate of a power switch designed to interrupt the input DC voltage to maintain constant power in the load. The rectifying smoothing means of the secondary circuit is connected to the load and through the feedback control circuits control the stabilization of the current to the LEDs. ST LED driver based on L6562A chip with adjustable brightness (STMicroelectronics was formed as a result of the Italian company SGS and French Thomson merged in 1997), 120 VAC input-Triac dimmable LED driver based on the L6562A http: // www. st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/APPLICATION_NOTE/CD00185256.pdf Fig. 11, p. 17.

However, this device has drawbacks in that when a switching power supply is used, broadband interference is generated in the network, which requires the use of effective filters, which leads to a rise in the cost of the structure, since additional winding elements lead to a significant increase in cost. The operation of a switching power supply with unfiltered voltage leads to an increase in the overall dimensions of the insulated transformer and forces the filtering to be carried out at 100 Hz. on the secondary side, this forces the use of electrolytic capacitors, which reduce the service life and temperature range of the device. Unreasonably overestimated requirements to maintain the stability of the output current lead to the complication and cost of stabilization schemes. A short circuit of the load when working on a large number of LEDs having a total voltage of 50-200 V causes damage to the measuring circuits.

The task of the switching power supply for LEDs is to increase the resistance to voltage drops of the supply circuit, increase the service life, expand the range of the output voltage, expand the temperature range while simultaneously adjusting the LED current depending on the ambient temperature while reducing cost and simplifying the design as a whole

The problem is solved in that the switching power supply for the LEDs contains a rectifying smoothing means of the primary circuit, designed to receive an alternating voltage current, generate a rectified smoothed voltage and supply this rectified smoothed voltage as an input DC voltage to an isolation transformer included to transmit the output energy of the primary side to the secondary side, damper assembly, connected in parallel with the primary winding of the transformer, generator a pulser, the output of which is connected to the gate of the power switch and designed to interrupt the input DC voltage to maintain constant power in the load, an auxiliary rectifier with a linear voltage regulator, connected between the isolation transformer and the pulse generator, rectifying the smoothing means of the secondary circuit connected to the load and through galvanic isolation element to a pulse generator.

The primary rectifying smoothing means of the primary circuit contains an interference suppression capacitor, a fuse, a limiting resistor, a rectifier diode bridge, which is connected to the primary winding of an isolation transformer through low-loss filter capacitors, a choke, and a low-loss filter capacitor.

The secondary circuit rectifier smoothing means contains a rectifier diode, and a group of parallel-connected smoothing low-loss capacitors connected to the load through the inductor of the protective device.

The isolation transformer contains an additional secondary winding, which is connected to a voltage and current sensor in the secondary circuit through a rectifier diode and a low-loss smoothing capacitor and is connected to a pulse generator through a galvanic isolation element.

Due to filter capacitors with low losses of the rectifying smoothing means of the primary circuit, the capacitance is optimally distributed between the primary and secondary side of the isolation transformer, which ensures resistance to voltage drops in the electric circuit (up to 400 V). This solution additionally provides suppression of interference of the switching power supply of the LEDs, which eliminates the need for additional high-pass filters at the input, which leads to a significant simplification of the design and its cost reduction.

Through the use of low-loss filter capacitors in the rectifying smoothing means of the primary circuit and secondary circuit, the service life of the switching power supply for LEDs is increased.

To power the pulse generator of the control circuit in steady state, an auxiliary rectifier with a linear voltage stabilizer on a high-voltage transistor is used, which can significantly increase the range of output voltages.

The protective device solves several main tasks: limiting the inrush current in the event of a short circuit in the load when the device is running and suppressing spurious oscillations resulting from this, additional high-pass filtering and discharge of the capacitors of the rectifying smoothing means of the secondary circuit after switching off the switching power supply. This connection solution provides resistance to changes in the output voltage range, increasing the service life, while reducing cost and simplifying the design as a whole.

The expansion of the temperature range with simultaneous correction of the LED current depending on the ambient temperature is solved by connecting a voltage and current sensor in the secondary circuit with galvanic isolation.

This scheme of switching on a switching power supply for LEDs allows at the same time to reduce the cost and simplify the design as a whole.

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

Figure 1 is a block diagram of a switching power supply for LEDs,

4 is a diagram of a switching power supply for LEDs

The switching power supply for LEDs contains a rectifying smoothing means of the primary circuit 1, an isolating transformer 2, a damper assembly 3, a pulse generator 4, a power switch 5, an auxiliary rectifier with a linear voltage stabilizer 6, a rectifying smoothing means of the secondary circuit 7, a protective device 8, a voltage sensor and current 9, galvanic isolation element 10.

The rectifying smoothing means of the primary circuit 1 contains an interference suppression capacitor C1, a fuse and a limiting resistor R3, a rectifying diode bridge B1, which is connected through the low loss filter capacitor C2, inductor L1 and a low loss filter capacitor C3 to the primary winding of isolation transformer 2

The rectifying smoothing means of the secondary circuit 7 contains a rectifying diode D6, and a group of parallel-connected smoothing capacitors with low losses C13, C14, C15, C16 connected to the load through the inductor L2 of the protective device 8. The isolation transformer 2 contains an additional secondary winding, which is through a rectifying diode D7 and a low-loss smoothing capacitor C11, connected to a voltage and current sensor in the secondary circuit 9 and through a galvanic isolation element 10 connected to a pulse generator 4. Int an isolation transformer 2 and a pulse generator 4 introduced an auxiliary rectifier with a linear voltage regulator 6.

The switching power supply for the LEDs operates as follows.

The input AC voltage of the network is supplied to the input of the rectifying smoothing means of the primary circuit 1, in which the impulse noise arising in the power source is filtered by the noise suppressing capacitor C1, then it is rectified through the rectifier diode bridge B1, at the output of which positive half-waves are formed with the amplitude of the input voltage and frequency 100 Hz repetitions, which are filtered by a low loss capacitor C2, then through a choke L1, are filtered by a low loss capacitor C3 and through a winding Isolation transformer 2 TR1 is supplied to drain Q2 of power switch 5.

The damper assembly 3, connected in parallel to the primary winding TR1 of the isolation transformer 2 and consisting of D1, D2, R12, C10, serves to form the optimal switching path of the power switch 5. Through the chain of resistors R7, R8, the capacitor C6 of the pulse generator 4 is charged, which ensures its start of work. The divider of the pulse generator 4, consisting of resistors R4, R5, R6, connected to the input MUL (pin 3) of the chip of the pulse generator 4, sets the maximum value of the current passing through the power switch 5, which sets the voltage drop across the resistors R17, R18 connected with the CS input (pin 4) of the pulse generator chip 4, at which the comparator of the chip is triggered, limiting the current in the primary circuit. Thus, the current through the power switch 5 is proportional to the magnitude of the input voltage, while the sinusoidal shape of the current consumption and the coincidence in phase of the voltage and current are set. The same current will flow through the auxiliary winding TR1 of the isolation transformer 2, which will lead to an increase in the magnetic flux in the core of the isolation transformer 2, while the self-induction EMF is induced in the secondary side of the isolation transformer 2. Ultimately, a positive voltage appears at the output of the diode D6 of the rectifying smoothing means of the secondary circuit 7. Through a resistor R11, connected between the auxiliary winding of the isolation transformer 2 and pin 5 of the pulse generator 4, the chip controller receives information about the completion of the next cycle of energy transfer from the inductance to the load. As soon as the voltage at pin 5 of the pulse generator 4 microcircuit becomes zero, the internal comparator of the microcircuit gives the command to open the power switch 5 and start the next accumulation cycle in accordance with the selected regulation of the pulse generator 4. To power the pulse generator 4 of the control circuit in steady state, serves as an auxiliary rectifier with a linear voltage stabilizer 6, made on C4, C5, R9, D4, Q1, D5, which can significantly expand the range of output voltage. Thus, on one chip of the pulse generator 4, two devices are implemented: a power converter and a power corrector. The voltage from the diode D6 of the rectifying smoothing means of the secondary circuit 7 is supplied to the load through low-loss filter capacitors C13, C14, C15, C16 and a series-connected inductor L2, while the outgoing current forms a voltage and current stabilizer 9 on the resistors R24, R25, R26 voltage drop proportional to the current value. This voltage is supplied through the galvanic isolation element 10 to the control input of the pulse generator 4, while the feedback is closed, which maintains a constant power consumed by the LEDs under conditions of changing the input network voltage in the range from 85 to 400 V. As a result, when operating a switching power supply for LEDs, the shape of the current consumed from the power supply coincides with the shape of the mains voltage, while the coefficient cos f is close to unity, which ensures high quality operation of this regular enrollment for mass use. The power factor corrector (KKM) chip used in the pulse generator of a pulsed LED power supply operates in a new mode for it as a constant power source. With increasing ambient temperature, the elements R24, R25, R26, R27 of the voltage and current sensor 9 and the galvanic isolation element 10 act on the input of the pulse generator 4, reducing the power consumption of the load and limiting the temperature increase. When the load breaks, a synchronous voltage increase occurs at the output filter capacitors with low losses C13, C14, C15, C16 of the rectifying smoothing means of the secondary circuit 7 and the capacitor C11 of the voltage and current sensor 9, while the proportionality is determined by the ratio of the number of turns of the additional secondary and auxiliary windings of the isolation transformer 2. The voltage increase on the capacitor C11 of the voltage and current sensor 9 occurs until the current begins to flow through the zener diode D8 of the voltage and current sensor 9 and, accordingly Namely, the OKI LED of the galvanic isolation element 10, thereby limiting the voltage to a level safe for the elements of the output filter. With a short circuit in the load, the inductor L2 of the protective device 8 limits the amplitude of the discharge current of the filtering capacitors with low losses C13, C14, C15, C16 of the rectifying smoothing means of the secondary circuit 7 at a level safe for the measuring circuits, and the elements R28, R29, C17, D9 of the protective device 8 suppress the oscillations arising from this, preventing the possibility of damage to the LEDs by a surge in voltage of reverse polarity. A prolonged short circuit will cause a voltage drop at the output of the auxiliary rectifier with a linear voltage regulator 6 to the value at which the pulse generator 4 turns off. After this, the capacitor C6 of the pulse generator 4 will charge and an attempt to start. This process will be repeated cyclically until the cause of the overload has been eliminated.

Thus, the proposed switching power supply for the LEDs is powered from a power supply of 80-400 V, 50 Hz, has an acceptable coefficient cos f, provides stabilization of the LED current with wide ranges of changes in the supply voltage and temperature. It has protection against overheating, from open circuit and short circuit in the LED circuit, against overcurrent of the power switch and guaranteed operation within 100,000 hours.

Claims (1)

A switching power supply for LEDs comprising a primary rectifying smoothing means for receiving an alternating voltage current, generating a rectified smoothed voltage and supplying this rectified smoothed voltage as an input DC voltage to an isolation transformer included to transmit the output energy of the primary side to the secondary side, a damper assembly connected in parallel with the primary winding of the transformer, a pulse generator, the output of which is connected inen with a power switch and designed to interrupt the input DC voltage to maintain constant power in the load, an auxiliary rectifier with a linear voltage regulator connected between an isolation transformer and a pulse generator, a rectifying smoothing means of the secondary circuit connected to the load and through the galvanic isolation element to the generator pulses, characterized in that the rectifying smoothing means of the primary circuit contains a fuse, anti-interference the first capacitor, the limiting resistor, the rectifier diode bridge, which is connected through the low-loss filter capacitors, the low-loss inductor and the filter capacitor to the primary winding of the isolation transformer, and the secondary rectifier smoothing means contains a rectifier diode, and a group of parallel low-level smoothing capacitors losses connected to the load through the inductor of the protective device, and the isolation transformer contains an additional secondary a winding, which is connected to a voltage and current sensor in the secondary circuit through a rectifier diode and a low-loss smoothing capacitor and is connected to a pulse generator through an galvanic isolation element.