CN205726618U

CN205726618U - LLC resonant converter circuit in lamp control system

Info

Publication number: CN205726618U
Application number: CN201620659588.6U
Authority: CN
Inventors: 张彬; 胡特奇; 王科; 李长建; 朱黎丽
Original assignee: Chongqing Can Yuan Electronics Co Ltd
Current assignee: Zhuhai Canyuan Electronic Technology Co ltd
Priority date: 2016-06-28
Filing date: 2016-06-28
Publication date: 2016-11-23
Anticipated expiration: 2026-06-28

Abstract

This utility model provides the LLC resonant converter circuit in a kind of lamp control system, described lamp control system includes PFC boost circuit, described PFC boost circuit arranges supply transformer PFC T1, pressure point A is drawn by commutation diode in auxiliary winding one end of described supply transformer PFC T1, this circuit includes: resonant control unit, including resonance control chip, chip has supply port, described pressure point A is connected to described supply port by a string steady unit, and the steady unit of described string includes switching tube Q10；The colelctor electrode of described switching tube Q10 is connected to pressure point A and is connected to the base stage of self by resistance R22；The anode that the base stage of described switching tube Q10 accesses ground and stabilivolt ZD10 by stabilivolt ZD10 is earth terminal；The emitter stage of switching tube Q10 accesses the anode of stabilivolt ZD10 by electric capacity C17 and accesses supply port by resistance J11.The LLC resonant converter circuit design that the utility model proposes steady unit of string, enables string steady unit to provide stable supply voltage to chip.

Description

LLC resonant converter circuit in lamp control system

Technical Field

The utility model relates to a lamps and lanterns control technical field, concretely relates to LLC resonant converter circuit for among lamps and lanterns control system.

Background

At present, in many switching power supplies, an LLC resonant converter circuit is usually designed to improve power conversion efficiency, and has the characteristics of small output ripple, simple filtering, large load adjustable range, and the like. For example, similar to a lamp such as an LED street lamp that provides a lighting function to a road, an LLC resonant circuit is involved in a lamp control system, because the LED street lamp cannot directly draw energy from a utility power grid, and a matched driving power supply is required. In an LED lamp control system, a high voltage signal is obtained after the voltage of commercial power is boosted by a power factor correction unit (PFC boosting), and then the high voltage signal is converted into low-voltage direct current meeting the driving requirement of an LED street lamp through an LLC resonant converter. The LLC resonant converter circuit has many structures in the field of power supply design, and some have half-bridge driving using discrete components, and some have half-bridge driving using a control chip. In a resonant half-bridge control circuit formed by an LLC resonant control chip, the power supply of the chip is usually directly connected to the auxiliary winding of a power supply transformer in a PFC boost circuit through a rectifier diode, and once the voltage signal induced on the auxiliary winding is unstable or even fluctuates greatly, the chip works under the influence, so that the resonant half-bridge is in an unstable working state. Furthermore, for two power tubes of the resonant half-bridge, some grids of the two power tubes are directly connected with corresponding ports of the chip, so that on-off speed driving of the power tubes is influenced to a certain extent, and abnormality of simultaneous conduction also occurs, and the conversion efficiency of the power supply is influenced.

SUMMERY OF THE UTILITY MODEL

To exist not enough among the prior art, the utility model provides a LLC resonant converter circuit among lamps and lanterns control system, this circuit use resonance control chip to design as giving first place to, and the steady unit of cluster has been designed at the power supply port of chip, makes the steady unit of cluster can provide stable supply voltage for the chip, with the normal operating of guaranteeing LLC resonant converter circuit.

In order to achieve the above purpose, the utility model adopts the following technical scheme:

an LLC resonant converter circuit in a lamp control system, the lamp control system including a PFC boost circuit, a power supply transformer being disposed in the PFC boost circuit, one end of an auxiliary winding of the power supply transformer leading out a voltage-taking point a through a rectifier diode, the LLC resonant converter circuit comprising:

the resonance control unit comprises a resonance control chip, the resonance control chip is provided with a power supply port, the voltage taking point is connected to the power supply port through a string stabilizing unit, and the string stabilizing unit comprises a switching tube Q10; the collector of the switching tube Q10 is connected to the voltage taking point and is connected to the base of the switching tube Q10 through a resistor R22; the base electrode of the switch tube Q10 is connected to the ground through a voltage regulator tube ZD10, and the anode of the voltage regulator tube ZD10 is the grounding end; the emitter of the switching tube Q10 is connected to the anode of the voltage regulator tube ZD10 through a capacitor C17 and is connected to the power supply port through a resistor J11.

Compared with the prior art, the utility model discloses following beneficial effect has:

the utility model provides an LLC resonant converter circuit is used in lamps and lanterns control system, acquire voltage signal through the power supply transformer auxiliary winding from PFC boost circuit, and utilize this voltage signal as resonance control chip's power supply, and send into resonance control chip's power pin through the steady unit of cluster, make resonance control chip can control the resonance half-bridge steadily, thereby make the LC resonance network of connection in resonance half-bridge rear side, the required stable DC voltage of synchronous rectification unit output lamps and lanterns.

Drawings

Fig. 1 is a schematic diagram of a PFC boost circuit of a lamp control system in front of an LLC resonant converter circuit according to the present invention;

fig. 2 is a schematic diagram of the LLC resonant converter circuit of the present invention.

Detailed Description

In order to make the utility model realize that technical means, creation characteristics, achievement purpose and effect are clearer and easily understand, it is right to combine below the figure and the detailed implementation mode the utility model discloses do further explanation:

referring to fig. 1, a schematic diagram of a PFC boost circuit of a lamp control system in front of an LLC resonant converter circuit is shown. The partial circuit is a boost type power factor correction circuit, and the boost type power factor correction circuit is mainly used for adjusting the waveform of input current through a special power factor correction control IC chip and compensating the phase difference between current and voltage, so that the power factor of a power grid is improved, and the efficient utilization rate of the power grid is guaranteed. In fig. 1, the PFC Vout is a signal output terminal of the PFC boost circuit, and the output voltage thereof is about 420V. The transformer T1 is a PFC power supply transformer, and as shown in fig. 1, one end (pin10) of a primary winding of the T1 is connected to a signal output end of the ac input rectifying and filtering unit, and the other end (pin8) leads out a signal output constituting the circuit, and one end (pin4) of an auxiliary winding of the power supply transformer T1 leads out a voltage tapping point a through D1, D2, and R18.

Referring to fig. 2, a schematic diagram of the LLC resonant converter circuit of the present invention is shown. With reference to fig. 1-2, the utility model provides a LLC resonant converter circuit among lamps and lanterns control system, lamps and lanterns control system includes PFC boost circuit, set up power supply transformer PFC T1 among the PFC boost circuit, power supply transformer PFC T1's auxiliary winding one end is drawn forth voltage taking point A through rectifier diode, LLC resonant converter circuit includes: the resonance control unit comprises a resonance control chip U900, the resonance control chip U900 is provided with a power supply port VCC, the voltage taking point A is connected to the power supply port (VCC pin) through a string of stabilizing units, and the string of stabilizing units comprise a switch tube Q10; the collector of the switching tube Q10 is connected to the voltage taking point A and is connected to the base of the switching tube Q10 through a resistor R22; the base electrode of the switch tube Q10 is connected to the ground through a voltage regulator tube ZD10, and the anode of the voltage regulator tube ZD10 is the grounding end; an emitter of the switching tube Q10 is connected to an anode of a voltage regulator tube ZD10 through a capacitor C17 and is connected to a power supply port VCC pin through a resistor J11.

In the scheme, the voltage of the point A is sent to the collector of the switching tube Q10, at the moment, the base of the switching tube Q10 is stabilized to 13V due to the existence of the voltage stabilizing tube ZD10, the output 3 pin (namely the emitter) of the switching tube Q10 is constantly at about 13-0.3V, and then the output 3 pin (namely the emitter) is applied to the power supply port of the resonance control chip U900 through the resistor J11, so that the power supply port VCC of the resonance control chip U900 is constantly operated at about 12.5V. At this time, no matter how the circuit voltage fluctuates, the voltage/current impact is borne on the switching tube Q10, and the chip U900 is well protected. The working current of the voltage regulator tube ZD10 is only required to be less than 1mA, so that the current required by the work can be provided for the chip U900, the power consumption of the voltage regulator tube ZD10 is low, and the circuit works stably and reliably. In some lamp control systems, a voltage stabilizing circuit is not provided with a switch tube, and voltage/current can be completely loaded on a voltage stabilizing tube, so that the voltage stabilizing tube is high in power consumption and easy to damage. The resistor R22 preferably takes a value of 3.9K, and the stabilized voltage of the voltage regulator tube ZD10 takes a value of 13V. The resistance J11 preferably takes on a value of 4.7 ohms. The rated working voltage of the capacitor C17 is 50V, and the effect of the capacitor C17 is to filter high-frequency noise.

The utility model discloses in, still be provided with diode D13 between the collecting electrode of switch tube Q10 and the projecting pole, diode D13's positive pole links to each other with switch tube Q10's projecting pole, diode D13's negative pole links to each other with switch tube Q10's collecting electrode. The diode D13 is provided here, so that VCC of LLC can normally feed back to pin 4 of U3, and the voltage at point a is disturbed by VCC of PFC.

Wherein, the series stabilizing unit further includes a filter capacitor bank, as shown in fig. 2, the filter capacitor bank includes: a capacitor C16 connected between the voltage taking point A and the ground, and a capacitor C60 and a capacitor C61 connected between the power supply port and the ground, wherein the capacitors C16 and C61 adopt polar capacitors. Here, the capacitor C16 filters the signal at point a (i.e. the signal before entering the string stabilizing unit), and the capacitor C61 and the capacitor C60 filter the signal output by the string stabilizing unit, so as to ensure that the voltage input to the chip U900VCC is stable and has no interference.

Because the utility model relates to an LLC resonant converter control circuit, consequently with traditional LLC resonant converter similar be also including the resonance half-bridge, chip U900 through control resonance half-bridge in two switch tubes switch on and close adjust their operating frequency (be referred to switching frequency for short) to this adjusts output voltage size, and two switch tubes duty cycle remain unchanged in whole control process. This is in contrast to the way the energy is delivered by the PWM controller, which is controlled by the duty cycle of the main switch. When the load is light, the working frequency is gradually increased and the load works in a voltage reduction area; and when the load is heavy, the working frequency is gradually reduced, and the working is in a boosting area.

As shown in fig. 2, the LLC resonant converter circuit further includes a resonant half-bridge formed by a switching tube Q5 and a switching tube Q6; the source electrode of the switching tube Q5 is connected with the drain electrode of the switching tube Q6 to form a series structure, and a series connection point is led out outwards and connected to the LC resonance network; the drain of the switching tube Q5 receives a voltage signal (i.e. PFCVout in fig. 1) output from the PFC boost circuit, and the gate is connected to a high-side driving output pin (HVG pin) of the resonant control chip through a first switching tube accelerating unit; the source of the switching tube Q6 is grounded, and the gate is connected to the low-side driving output pin (LVG pin) of the resonance control chip through the second switching tube acceleration unit. The chip U900 controls the on and off of the Q5 and the Q6, so that the LC resonant network continuously transmits the electric energy to the secondary output terminal, and the electric energy is converted into direct current through the synchronous rectification unit of the secondary output terminal and loaded on the lamp load. And the purpose of designing the switch tube accelerating unit between the gates of the switch tube Q5 and the switch tube Q6 and the corresponding driving pins of the chip is to prevent the Q5 and the Q6 from being conducted simultaneously.

As can be seen from fig. 2, the LC resonant network is formed by the primary windings L (pin12-pin13) and C33 of the resonant transformer LLC T1, and the secondary winding side of the resonant transformer LLC T1 is provided with the synchronous rectifier 1(pin2-pin5) and the synchronous rectifier 2(pin1-pin4) to rectify the secondary induced voltage signal of the resonant transformer LLC T1 and transmit the rectified signal to the street lamp. Here, both the synchronous rectification 1 and the synchronous rectification 2 are formed by using a TEA1791A synchronous rectification chip. Belongs to the synchronous rectification technology with wider application, thereby saving the specific circuit design. Meanwhile, the resonant transformer LLC T1 is further designed with a primary auxiliary power supply winding pin9-pin10 and a secondary auxiliary power supply winding pin6-pin7, wherein the primary auxiliary power supply winding pin9-pin10 is designed with a diode D11, a capacitor C15 and a capacitor C18, and the cathode of the diode D11 is connected to the point A through a resistor R81. The circuit designed by the secondary auxiliary power winding pin6-pin7 is irrelevant to the invention and will not be described in detail here.

In the above scheme, the first switching tube accelerating unit includes a voltage regulator ZD50, a diode D56, a resistor R13, a resistor R9, and a switching tube Q51; referring to fig. 2, a high-side driving output pin (HVG pin, i.e. pin 15) of a resonant control chip U900 is connected to a cathode of a voltage regulator tube ZD50, an anode of a diode D56 and a base of a switch tube Q51, an anode of the voltage regulator tube ZD50 is connected to a high-side driving floating ground pin (OUT pin, i.e. pin 14) of the resonant control chip, a cathode of the diode D56 is connected to a gate of a switch tube Q5 through a resistor R13, an emitter of the switch tube Q51 is connected to a gate of a switch tube Q5 through a resistor R9, and a collector of the switch tube Q51 is connected to a source of a switch tube Q5. A resistor R10 with the resistance of 10K ohms is further arranged between the grid electrode and the source electrode of the switching tube Q5 to protect the switching tube Q5.

When the Q5 is controlled to be conducted, a control signal output by an HVG pin of the chip U900 is sent to a grid electrode of the Q5 through the D56 and the R13, the resistance value of the R13 is small, the Q5 is enabled to be conducted rapidly, and the rising edge time is short; when the control Q5 is switched off, a control signal output by an HVG pin of the chip U900 is loaded to a base electrode of the switching tube Q51, so that the Q51 is switched on, and at the moment, a grid signal of the MOS tube Q5 passes through the diode D56, the resistors R13 and R9, and the switching tube Q51 is released, so that the switching-off is accelerated. The switching tube Q51 preferably uses a PNP transistor.

In the above solution, the second switch tube accelerating unit has the same structure as the first switch tube accelerating unit, that is, the second switch tube accelerating unit includes a voltage regulator ZD51, a diode D55, a resistor R15, a resistor R11, and a switch tube Q50; referring to fig. 2, a low-side driving output pin (LVG pin) of the resonance control chip is connected to a cathode of a voltage regulator ZD51, an anode of a diode D55 and a base of a switch tube Q50, an anode of the voltage regulator ZD51 is grounded, a cathode of the diode D55 is connected to a gate of the switch tube Q6 through a resistor R15, an emitter of the switch tube Q50 is connected to a gate of a switch tube Q6 through a resistor R11, and a collector of the switch tube Q50 is connected to a source of a switch tube Q6. A resistor R12 with the resistance of 10K ohms is further arranged between the grid electrode and the source electrode of the switching tube Q6 to protect the switching tube Q6.

When the Q6 is controlled to be conducted, a control signal output by the LVG pin of the chip U900 is sent to the grid of the Q6 through the D55 and the R15, the resistance value of the R15 is small, the Q6 is enabled to be conducted rapidly, and the rising edge time is short; when the control Q6 is switched off, a control signal output by the LVG pin of the chip U900 is loaded to the base of the switch tube Q50, so that the Q50 is switched on, at the moment, a gate signal of the MOS tube Q6 passes through the diode D55, the resistors R15 and R11, and the switch tube Q50 is released, so that the switching-off is accelerated. The switching tube Q50 preferably uses a PNP transistor.

In the first switch tube accelerating unit and the second switch tube accelerating unit, the stabilized voltage of the voltage-regulator tubes ZD50 and ZD51 is preferably selected to be 39V; the preferential parameters of the diodes D56 and D55 are 30V/0.2A (wherein 30V is the maximum reverse voltage borne by the diodes, and 0.2A is the maximum forward current flowing through the diodes); the types of the transistors Q51 and Q50 are also the same. However, in the first switch tube accelerating unit, R13 preferably takes 10 ohms, and R9 preferably takes 15 ohms; in the second switch tube acceleration unit, R15 preferably takes 15 ohms, and R11 preferably takes 10 ohms. Comparing with fig. 2, the resistance value is designed so that the upper half-bridge driving and the lower half-bridge driving are different from the discharge resistance value, so as to ensure the conduction dead time of the upper bridge and the lower bridge, and effectively avoid the abnormality that the upper MOS tube and the lower MOS tube are conducted simultaneously.

As can be seen from fig. 2, the resonance control chip U900 of the present invention has other pins besides the VCC pin (12 pins), the HVG pin (15 pins), the LVG pin (11 pins) and the OUT pin (14 pins), which are already mentioned above, specifically as follows:

pin 1 — CSS pin: a soft start pin. The pin is grounded through R61 and C57, and a capacitor R57 is arranged between the pin and the 4 pins to determine the highest working frequency in soft start. The purpose of soft-start is to gradually increase the converter power during start-up to eliminate excessive inrush current at start-up.

Pin 2 — DELAY pin: the overload current delays the turn-off pin. The pin is tied to ground R59, C53 to set the maximum duration of the overload current.

Pin 3 — CF pin: a timing capacitor pin. The pin is connected to a capacitor C54 to ground, and cooperates with a 4-pin resistor R58 to ground to set the switching frequency of the oscillator.

4 pins — RFMIN pin: the lowest oscillation frequency setting pin. The pin provides a 2V reference voltage, and the load network comprises three branches: a resistor R58 arranged between the 4 pins and the ground and used for setting the lowest oscillation frequency; secondly, a resistor R60 is connected with a pin 4, an optical coupler (U4) controlled by a feedback loop is grounded and used for adjusting the oscillation frequency of the exchanger, when the circuit works, the optical coupler adjusts current through the branch circuit, so that the oscillation frequency is adjusted, the output voltage is changed, and when the phototransistor is saturated, the resistor R60 determines the maximum frequency of half-bridge oscillation. And thirdly, soft start is realized by an R57 and C57 network arranged between 4 feet-1 feet-ground.

Pin 5-STBY pin: intermittent operating mode threshold pin (<1.25V), i.e. standby mode. As can be seen from FIG. 2, the pin is connected into an optical coupler U4 through resistors R63 and R64. The voltage is controlled by the feedback voltage of the later stage and compared with the internal 1.25V reference voltage, if the voltage of the 5 pins is less than 1.25V, the chip enters a static state, and only a small static working current exists. When the voltage of the 5 pin exceeds the reference voltage by 50mV, the chip starts to work again.

Pin 6-ISEN pin: the current detection signal is input to the pin. As seen from FIG. 2, the pin uses a capacitive shunt non-destructive current detection method to detect the magnitude of current in the main loop. In fig. 2, C63, C62, R66, D53, D54, C56, and R65 constitute a nondestructive current detection circuit.

Pin 7 — LINE pin: and inputting a voltage detection pin. As seen in fig. 2, the pin is connected to the output part of the PFC circuit by a voltage dividing resistor for protection. When the detected voltage is below 1.25V, the output is turned off and the soft-start capacitor is released. When the detection voltage is higher than 1.25V, the soft start is restarted.

Pin 8 — DIS pin: the latch drives the close pin. The pin is internally connected with a comparator, when the pin voltage exceeds 1.85V, the chip is shut down in a blocking mode, and the operation can be restarted only when the chip operating voltage Vcc is reduced to be lower than UVL0 threshold. As seen in fig. 2, the pin is connected to an optocoupler U3, and the optocoupler U3 constitutes an output overvoltage protection unit (the specific circuit is not shown). When the output voltage of the rear stage is overlarge, the output voltage is fed back to the DIS pin through the optocoupler, so that the chip drive is closed.

Pin 9 — PFC-STOP pin: and opening a control pin of the PFC controller. The utility model is not used.

Pin 10 — GND pin: a chip ground pin.

16 pins-VBOOT pin: the high-side gate drives the floating supply pin. A bootstrap capacitor Cboot, namely C59, is connected between the pin and the 14 pin (OUT), and is driven by a bootstrap diode inside the chip and the low-side gate driver synchronously.

Finally, although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the present invention can be modified or replaced by other means without departing from the spirit and scope of the present invention, which should be construed as limited only by the appended claims.

Claims

1. An LLC resonant converter circuit in a lamp control system is connected to the rear side of a PFC boost circuit of the lamp control system, a power supply transformer is arranged in the PFC boost circuit, and one end of an auxiliary winding of the power supply transformer is led out of a voltage taking point A through a rectifier diode, and the LLC resonant converter circuit is characterized by comprising:

the resonance control unit comprises a resonance control chip, the resonance control chip is provided with a power supply port, the voltage taking point A is connected to the power supply port through a string stabilizing unit, and the string stabilizing unit comprises a switching tube Q10; the collector of the switching tube Q10 is connected to the voltage taking point A and is connected to the base of the switching tube Q10 through a resistor R22; the base electrode of the switch tube Q10 is connected to the ground through a voltage regulator tube ZD10, and the anode of the voltage regulator tube ZD10 is the grounding end; the emitter of the switching tube Q10 is connected to the anode of the voltage regulator tube ZD10 through a capacitor C17 and is connected to the power supply port through a resistor J11.

2. The LLC resonant converter circuit as claimed in claim 1, wherein a diode D13 is further disposed between the collector and emitter of said switching transistor Q10, the anode of said diode D13 is connected to the emitter of switching transistor Q10, and the cathode of said diode D13 is connected to the collector of switching transistor Q10.

3. The LLC resonant converter circuit in a lamp control system of claim 1 or 2, wherein said string stabilizing unit further comprises a filter capacitor bank, said filter capacitor bank comprising:

a capacitor C16 connected between the voltage taking point A and the ground, and a capacitor C60 and a capacitor C61 connected between the power supply port and the ground, wherein the capacitors C16 and C61 adopt polar capacitors.

4. The LLC resonant converter circuit in the lamp control system of claim 1, further comprising a resonant half-bridge consisting of a switching tube Q5 and a switching tube Q6; wherein,

the source electrode of the switching tube Q5 is connected with the drain electrode of the switching tube Q6 to form a series structure, and a series connection point is led out outwards and connected to the LC resonance network;

the drain electrode of the switching tube Q5 receives a voltage signal output from the PFC boost circuit, and the grid electrode of the switching tube Q5 is connected with a high-end driving output pin of the resonance control chip through a first switching tube accelerating unit;

the source electrode of the switching tube Q6 is grounded, and the grid electrode of the switching tube Q6 is connected with the low-end driving output pin of the resonance control chip through the second switching tube accelerating unit.

5. The LLC resonant converter circuit in the lamp control system of claim 4, wherein the first switch tube accelerating unit comprises a voltage regulator ZD50, a diode D56, a resistor R13, a resistor R9 and a switch tube Q51;

The high-end driving output pin of the resonance control chip is connected to the cathode of a voltage regulator tube ZD50, the anode of a diode D56 and the base of a switch tube Q51, the anode of the voltage regulator tube ZD50 is connected to the high-end driving floating pin of the resonance control chip, the cathode of the diode D56 is connected with the grid of a switch tube Q5 through a resistor R13, the emitter of the switch tube Q51 is connected with the grid of a switch tube Q5 through a resistor R9, and the collector of the switch tube Q51 is connected with the source of a switch tube Q5.

6. The LLC resonant converter circuit as claimed in claim 5, wherein a resistor R10 having a resistance of 10K ohms is further provided between the gate and source of said switching transistor Q5.

7. The LLC resonant converter circuit in the lamp control system of claim 5 or 6, wherein the second switch tube accelerating unit comprises a voltage regulator ZD51, a diode D55, a resistor R15, a resistor R11 and a switch tube Q50;

the low-end driving output pin of the resonance control chip is connected to the cathode of a voltage regulator tube ZD51, the anode of a diode D55 and the base of a switch tube Q50, the anode of the voltage regulator tube ZD51 is grounded, the cathode of the diode D55 is connected with the gate of a switch tube Q6 through a resistor R15, the emitter of the switch tube Q50 is connected with the gate of a switch tube Q6 through a resistor R11, and the collector of the switch tube Q50 is connected with the source of a switch tube Q6.

8. The LLC resonant converter circuit as claimed in claim 7, wherein a resistor R12 of 10K ohms is further provided between the gate and source of said switching transistor Q6.