CN214627432U - Isolated AC-DC constant current driver and LED lighting equipment - Google Patents

Isolated AC-DC constant current driver and LED lighting equipment Download PDF

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CN214627432U
CN214627432U CN202120234953.XU CN202120234953U CN214627432U CN 214627432 U CN214627432 U CN 214627432U CN 202120234953 U CN202120234953 U CN 202120234953U CN 214627432 U CN214627432 U CN 214627432U
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胡炎申
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Moso Power Supply Technology Co ltd
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Moso Power Supply Technology Co ltd
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Abstract

The application discloses an isolated AC-DC constant current driver and LED lighting equipment, wherein the isolated AC-DC constant current driver comprises an isolated PFC main converter and a DC-DC auxiliary converter; the isolated PFC main converter comprises a PFC power conversion unit, a voltage converter and a main output port, wherein the voltage converter comprises a first main winding, a second main winding, a first auxiliary winding and a second auxiliary winding; the first main winding and the first auxiliary winding are mutually induced, the second main winding and the second auxiliary winding are mutually induced, and the DC-DC auxiliary converter comprises an auxiliary input port and an auxiliary output port; the input end of the PFC power conversion unit is connected with the main input port, and the auxiliary output port is connected with the main output port in series to form a total output port. In this application, only a part of electric energy provides to the load through the two-stage transform, compares in the condition that full power all passes through the two-stage transform, has reduced the consumption, has improved whole conversion efficiency.

Description

Isolated AC-DC constant current driver and LED lighting equipment
Technical Field
The present disclosure relates to circuit technologies, and particularly to an isolated AC-DC (alternating current-direct current) constant current driver and a Light Emitting Diode (LED) lighting device.
Background
The LED is applied to lighting devices, and has the advantages of wide color gamut, high brightness, large viewing angle, low power consumption, long service life, and the like, so that the LED lighting devices are widely applied to various lighting display fields. Such as the common stock exchange and financial information display, airport flight dynamic information display, port and station passenger guidance information display, stadium information display, road traffic information display, electric power scheduling, vehicle dynamic tracking and other scheduling command center information display, market shopping center and other service fields business propaganda information display, advertising media products and the like.
Generally, a driving power source is required to drive an LED lighting device in normal operation, the driving power source is generally a constant current driver, and when the power of the LED lighting device is relatively high, the constant current driver needs to have a Power Factor Correction (PFC) function.
The current constant current driver comprises a single stage and a plurality of stages. Although the single-stage constant-current driver has a simple structure and low cost, the single-stage constant-current driver cannot simultaneously give consideration to input high power factor and output low ripple, and even the power tube still has overhigh voltage or current stress. Therefore, a multi-stage constant current driver is generally selected in the industry, wherein two stages are common, and in the two-stage constant current driver, a front-stage PFC converter is used for adjusting an input power factor and balancing input and output energy; and the rear-stage direct current (DC-DC) auxiliary converter is used for adjusting the output voltage and reducing the output ripple voltage or current.
However, the ac output of the two-stage constant current driver can obtain the total output after the two-stage full power conversion, and the power consumption is relatively high, resulting in low overall conversion rate.
SUMMERY OF THE UTILITY MODEL
The application aims to provide an isolated AC-DC constant current driver and an LED lighting device, which are low in power consumption and high in overall conversion efficiency.
A first aspect of the present application provides an isolated AC-DC constant current driver, including: isolating the PFC main converter and the DC-DC auxiliary converter; the isolated PFC main converter comprises a PFC power conversion unit, a voltage converter and a main output port, wherein the voltage converter comprises a first main winding, a second main winding, a first auxiliary winding and a second auxiliary winding; the first main winding and the first auxiliary winding are mutually induced, the second main winding and the second auxiliary winding are mutually induced, and the DC-DC auxiliary converter comprises an auxiliary input port and an auxiliary output port; the output end of the PFC power conversion unit is connected with the first main winding; the first auxiliary winding is connected with the main output port; the second auxiliary winding is connected with the auxiliary input port; the auxiliary output port and the main output port are connected in series to form a total output port; after receiving the direct current from the PFC power conversion unit, the voltage converter: the main voltage is converted through the first main winding and the first auxiliary winding and is output to a main output port, and the main output port transmits the main voltage to a main output port; converting an auxiliary voltage through the second main winding and the second auxiliary winding, and outputting the auxiliary voltage to an auxiliary input port; and after receiving the auxiliary voltage from the auxiliary input port, the DC-DC auxiliary converter processes the auxiliary voltage and outputs the processed auxiliary voltage to the auxiliary output port, and the auxiliary output port transmits the auxiliary voltage to the total output port.
In one embodiment, the isolated AC-DC constant current driver further comprises: a PFC controller; the isolated PFC main converter further comprises: a main power switch tube; the main power switch tube is connected with the first main winding; the PFC controller comprises a main feedback port, a first main acquisition port, a main control port, a main reference voltage port and a main reference sawtooth wave signal port; the main feedback port is connected with the main output port, the first main acquisition port is connected with the second main winding, and the main control port is connected with the control end of the main power switch tube; the PFC controller receives the main voltage from the main feedback port, the voltage of a second main winding from the first main acquisition port, the main reference voltage from the main reference voltage port and a main reference sawtooth wave signal from the main reference sawtooth wave signal port; comparing the main voltage with the main reference voltage to form a voltage error signal; comparing the voltage error signal with the main reference sawtooth wave signal to form a stop pulse signal; forming a start pulse signal based on the voltage of the second main winding; and controlling the on and off of the main power switch tube by using the stop pulse signal and the start pulse signal.
In one embodiment, the PFC controller further comprises a second primary acquisition port; the second main acquisition port is connected with the main power switch tube; the PFC controller also receives the voltage of a main power switch tube from the second main acquisition port; comparing the voltage error signal with the main reference sawtooth wave signal to form a stop pulse signal includes: and comparing the voltage error signal with the voltage of the main power switch tube to form a comparison result, and comparing the main reference sawtooth wave signal with the comparison result to form a stop pulse signal.
In one embodiment, isolating the PFC main converter further comprises: a first main collecting part and a second main collecting part; the first main acquisition part is connected between the first main acquisition port and the second main winding; the second main collecting part is connected with the main power switch tube; the first main collecting port collects the voltage of the second main winding through the first main collecting part, and the second main collecting port collects the voltage of the main power switch tube through the second main collecting part.
In one embodiment, a PFC controller includes a main reference voltage source, a main reference sawtooth signal source, a first main comparator, a second main comparator, a third main comparator, and a flip-flop; the trigger is provided with an S port, a Q port and an R port; the negative input end of the first main comparator is connected with the main feedback port, the positive input end of the first main comparator is connected with a main reference voltage source through a main reference voltage port, and the output end of the first main comparator is connected with the positive input end of the second main comparator; the negative input end of the second main comparator is connected with the second main acquisition port, and the output end of the second main comparator is connected with the positive input end of the third main comparator; the negative input end of the third main comparator is connected with the main reference sawtooth wave signal source through a main reference sawtooth wave signal port, and the output end of the third main comparator is connected with the R port; the Q port is connected with the main control port, and the S port is connected with the first main acquisition port; the first master comparator is to: comparing the main voltage with the main reference voltage to form a voltage error signal; the second master comparator is to: comparing the voltage error signal with the voltage of the main power switch tube to form a comparison result; the third master comparator is to: comparing the main reference sawtooth wave signal with the comparison result to form a stop pulse signal; the trigger is used for: forming a start pulse signal based on the voltage of the second main winding; and controlling the on and off of the main power switch tube by using the stop pulse signal and the start pulse signal.
In one embodiment, the isolated AC-DC constant current driver further comprises: a DC-DC controller; the DC-DC auxiliary converter further includes: an auxiliary power switch tube; the DC-DC controller comprises an auxiliary feedback port, an auxiliary control port, an auxiliary reference current port and an auxiliary reference sawtooth wave signal port; the auxiliary feedback port is connected with the main output port, and the auxiliary control port is connected with the control end of the auxiliary power switch tube; the main output port outputs a main current after receiving the main voltage and the auxiliary voltage; the total current is transmitted to the auxiliary feedback port; after the DC-DC controller receives the total current from the auxiliary feedback port, the auxiliary reference current from the auxiliary reference current port and the auxiliary reference sawtooth wave signal from the auxiliary reference sawtooth wave signal port, comparing the total current with the auxiliary reference current to form a voltage error signal; and comparing the voltage error signal with the auxiliary reference sawtooth wave signal to form a control signal, and transmitting the control signal to the control end of the auxiliary power switch tube.
In one embodiment, the DC-DC auxiliary converter further comprises: an auxiliary collecting member; the auxiliary feedback port collects the total current through the auxiliary collecting part.
In one embodiment, a DC-DC controller includes: the auxiliary reference current source comprises a first auxiliary comparator, a second auxiliary comparator, an auxiliary reference current source and an auxiliary reference sawtooth wave signal source; the negative input end of the first auxiliary comparator is connected with the auxiliary feedback port, the positive input end of the first auxiliary comparator is connected with the auxiliary reference current source through the auxiliary reference current port, and the output end of the first auxiliary comparator is connected with the positive input end of the second auxiliary comparator; the negative input end of the second auxiliary comparator is connected with an auxiliary reference sawtooth wave signal source through an auxiliary reference sawtooth wave signal port, and the output end of the second auxiliary comparator is connected with an auxiliary control port; the first auxiliary comparator is for: comparing the total current with the auxiliary reference current to form a voltage error signal; the second auxiliary comparator is for: and comparing the voltage error signal with the auxiliary reference sawtooth wave signal to form a control signal, and transmitting the control signal to the control end of the auxiliary power switch tube.
In one embodiment, the isolated PFC main converter comprises a flyback converter or a forward converter; the DC-DC auxiliary converter comprises one of a buck converter, a boost converter, a buck-boost converter, a flyback converter, a forward converter, a Cuk converter, a single-ended primary inductance type converter and a zero-voltage switch converter.
A second aspect of the application provides an LED lighting device comprising an isolated AC-DC constant current driver according to any one of the first aspects of the application.
In the constant current driver with the isolation structure, part of power is only converted in a single stage, and part of power is converted in two stages, so that the total power consumption is reduced, and the overall conversion efficiency is improved.
Drawings
In order to more clearly explain the technical solution of the present application, the drawings used in the embodiments will be briefly described below.
Fig. 1 is a schematic diagram of an isolated AC-DC constant current driver provided in one embodiment of the present application;
fig. 2 is a schematic diagram of an isolated AC-DC constant current driver provided in another embodiment of the present application;
fig. 3 is a schematic diagram of an isolated AC-DC constant current driver provided in another embodiment of the present application;
fig. 4 is a schematic diagram of an isolated AC-DC constant current driver provided in another embodiment of the present application;
FIG. 5 is a schematic diagram of a DC-DC auxiliary converter provided in an alternative embodiment of the present application;
FIG. 6 is a schematic diagram of a DC-DC auxiliary converter provided in an alternative embodiment of the present application;
FIG. 7 is a schematic diagram of a DC-DC auxiliary converter provided in an alternative embodiment of the present application;
fig. 8 is a schematic diagram of a DC-DC auxiliary converter provided in an alternative embodiment of the present application.
Description of reference numerals:
the isolated PFC controller comprises an isolated PFC main converter 10, a PFC power conversion unit 11, a voltage converter 12, a first main winding 121, a first auxiliary winding 122, a second main winding 123, a second auxiliary winding 124, a DC-DC auxiliary converter 20, a PFC controller 30, a DC-DC controller 40, an alternating current power supply 50, a load 60, main input ports 1 and 2, main output ports 3 and 4, auxiliary input ports 5 and 6 and auxiliary output ports 7 and 8.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application.
Referring to fig. 1 to 8, an isolated AC-DC constant current driver according to an embodiment of the present disclosure includes an isolated PFC main converter 10 and a DC-DC auxiliary converter 20.
The isolated PFC main converter 10 comprises a PFC power conversion unit 11, a voltage converter 12 and a main output port, wherein the voltage converter 12 comprises a first main winding 121, a second main winding 123, a first auxiliary winding 122 and a second auxiliary winding 124; the first main winding 121 and the first auxiliary winding 122 mutually induce, and the second main winding 123 and the second auxiliary winding 124 mutually induce. The DC-DC auxiliary converter 20 includes an auxiliary input port and an auxiliary output port.
The input end of the PFC power conversion unit 11 is connected to the main input port, and the output end of the PFC power conversion unit 11 is connected to the first main winding 121; the first auxiliary winding 122 is connected to the main output port; the second auxiliary winding 124 is connected to the auxiliary input port; the auxiliary output port and the main output port are connected in series to form a total output port.
Specifically, after receiving the dc power from the PFC power conversion unit 11, the voltage converter 12: converting a main voltage through the first main winding 121 and the first auxiliary winding 122, and outputting the main voltage to a main output port, which transmits the main voltage to a main output port; the auxiliary voltage is converted through the second main winding 123 and the second auxiliary winding 124, and the auxiliary voltage is output to the auxiliary input port; the DC-DC auxiliary converter 20 receives the auxiliary voltage from the auxiliary input port, processes the auxiliary voltage, and outputs the processed auxiliary voltage to the auxiliary output port, and the auxiliary output port transmits the auxiliary voltage to the main output port.
As can be seen from the above, the PFC power conversion unit 11 only performs a single-stage conversion on part of the output power to the load 60. Since the DC-DC auxiliary converter 20 provides the load 60 with a part of power through two-stage conversion, that is, only a part of power is converted through two-stage conversion as a whole, power consumption can be reduced by performing the part of power through two-stage conversion as compared with a method in which all output power is converted through two-stage conversion.
The PFC power conversion unit 11 further includes a main input port, and then, when the isolated AC-DC constant current driver provided in the above embodiment is applied, the main input port is connected to the AC power supply 50, and the total output port after the main output port and the auxiliary output port are connected in series is connected to the load 60. Of course, the load 60 may be any device that needs to be powered, and in the embodiment of the present application, a string of LEDs is used as the load 60 for illustration. The main output port provides the main voltage Vo1 to the load 60 and the auxiliary output port provides the auxiliary voltage Vo2 to the load 60, so that the total voltage of the load 60 is the sum of the main voltage Vo1 and the auxiliary voltage Vo 2. The main output port forms a direct current bus.
After the alternating current power supply 50 and the LED light string are connected, wherein the current provided by the alternating current power supply 50 passes through the PFC power conversion unit 11 and the first main winding 121, and is directly output to the LED light string from the main output port in the form of the main voltage Vo 1; the current provided by the ac power source 50 is converted into a voltage through the PFC power conversion unit 11 and the second main winding 123, and then is output from the auxiliary output port to the DC-DC auxiliary converter 20 in the form of an auxiliary voltage Vo2, and the DC-DC auxiliary converter 20 adjusts the voltage and then outputs the voltage to the LED string.
In an alternative embodiment, in which the resistances of the first and second main windings 121 and 123 are equal, the resistance of the first auxiliary winding 122 is less than the resistance of the second auxiliary winding 124, so that, with the same current, the main voltage Vo1 is greater than the auxiliary voltage Vo2, and the output power of the main output port is greater than the output power of the auxiliary output port. Therefore, the conversion efficiency can be improved better.
It can be seen that the PFC power conversion unit 11 provides most of the output power to the LED string and is only a single stage power conversion. The DC-DC auxiliary converter 20 provides a small portion of the output power to the string, and although the power provided by the DC-DC auxiliary converter 20 is converted in two stages, it only processes a small portion of the output power, i.e., only a small portion of the output power is converted in two stages.
Specifically, assume that the conversion efficiency of the isolated PFC main converter 10 is ηPFCConversion efficiency of the DC-DC auxiliary converter 20 is etaDC-DC,PPFC、PDC-DC、PoutFor the output power of the isolated PFC main converter 10, the output power of the DC-DC auxiliary converter 20, and the overall output power, respectively, the overall efficiency is:
Figure BDA0002920041690000061
let PDC-DC=10%xPoutAnd then:
Figure BDA0002920041690000062
is additionally provided with etaDC-DC90%, the overall conversion efficiency ηtotal=98.9%xηPFC
As can be seen from the above, if the output power ratio of the DC-DC auxiliary converter 20 is 10%, even if the conversion efficiency of the DC-DC auxiliary converter 20 is as low as 90%, the overall efficiency η istotalClose to 99%, very close to the conversion efficiency of a pure single stage converter directly provided to the LED string. Therefore, the isolated AC-DC constant current driver provided by the embodiment of the application has lower power loss and can improve the overall efficiency.
In the embodiment of the application, most of the electric energy provided by the ac power supply 50 is transmitted to the LED light string through single conversion, and a small part of the electric energy is transmitted to the LED light string through primary and secondary conversion. Therefore, the power consumption is reduced, and the overall conversion efficiency is improved. In addition, because the DC-DC auxiliary converter 20 only converts a small part of electric energy, the voltage and current stress of the internal devices is also small, and the cost of the components can be reduced.
The voltage converter 12 described above may be a transformer or inductor T1 of the four-winding type having a first main winding 121, a second main winding 123, a first auxiliary winding 122, and a second auxiliary winding 124.
In an alternative embodiment, referring to fig. 2 and fig. 3, the isolated AC-DC constant current driver further includes a PFC controller 30; the isolated PFC main converter 10 also includes a main power switch Q1.
The main power switch Q1 is connected to the first main winding 121.
The PFC controller 30 includes a main feedback port a1, a first main acquisition port a2, a main control port a3, a main reference voltage port a4, and a main reference sawtooth signal port a 5; the main feedback port a1 is connected with the main output port, the first main collecting port a2 is connected with the first auxiliary winding 122, and the main control port a3 is connected with the control end of the main power switch tube Q1.
The PFC controller 30 is configured to receive a main voltage Vo1 of the main output port through a main feedback port a1, receive a voltage of the second main winding 123 through a first main collecting port a2, receive a main reference voltage through a main reference voltage port a4, and receive a main reference sawtooth signal through a main reference sawtooth signal port a 5; the main power switch Q1 is then controlled to turn on and off using the main voltage Vo1 at the main output port, the voltage at the second main winding 123, the main reference voltage, and the main reference sawtooth signal.
Specifically, the control process of the PFC controller 30 is as follows: after receiving the main voltage Vo1 from the main output port of the main feedback port a1, the main reference voltage from the main reference voltage port a4, the main reference sawtooth signal from the main reference sawtooth signal port a5, and the voltage from the second main winding 123 of the first main pickup port a2, the main voltage Vo1 from the main output port is compared with the main reference voltage, and a voltage error signal is formed based on the comparison result. And comparing the main reference sawtooth wave signal with the voltage error signal, and forming a stop pulse signal according to the comparison result. The start pulse signal is formed using the voltage of the second main winding 123. The stop pulse signal and the start pulse signal are used for controlling the on and off of the main power switch tube Q1. The stop pulse signal and the start pulse signal form a Pulse Width Modulation (PWM) control signal, and the on/off of the main power switching tube Q1 can be controlled by the PWM control signal.
That is, the main voltage Vo1 of the main output port is fed back to the PFC controller 30 through the main feedback port a1, the main reference voltage is supplied to the PFC controller 30 through the main reference voltage port a4, and the PFC controller 30 compares the main voltage Vo1 of the main output port with the main reference voltage and then forms a voltage error signal. Then, the PFC controller 30 compares the voltage error signal with the main reference sawtooth signal to generate a stop pulse signal; the PFC controller 30 may then control the turn off of the main power switch Q1 using the stop pulse signal.
The voltage of the second main winding 123 is fed back to the PFC controller 30 through the first main collecting port a2, and the PFC controller 30 generates a start pulse signal by using the voltage of the second main winding 123; the PFC controller 30 then uses the start pulse signal to control the turn-on of the main power switch Q1.
The control mode can control the main voltage Vo1 of the main output port in a closed loop mode, and can also realize that the input current and the output voltage are sine waves with the same frequency and the same phase so as to achieve power factor correction and better power factor and further realize zero pollution to a power grid.
In an alternative embodiment, referring to fig. 2 and 3, the PFC controller 30 further includes a second primary collection port a 6; the second primary collection port a6 is connected to the primary power switch Q1. The PFC controller is further configured to receive the voltage of the main power switch Q1 through the second main acquisition port a 6.
Wherein, the PFC controller 30 compares the voltage error signal with the main reference sawtooth signal to form a stop pulse signal including: and comparing the voltage error signal with the voltage of the main power switch tube Q1 to form a comparison result, and comparing the main reference sawtooth wave signal with the comparison result to form a stop pulse signal. That is, the second main collecting port a6 is arranged to collect the voltage of the main power switch tube Q1, so that the voltage error signal is compared with the voltage of the main power switch tube Q1 before the main reference sawtooth wave signal and the voltage error signal are compared, and then the comparison result is compared with the main reference sawtooth wave signal. The peak current of the main power switch Q1 can thus be controlled.
In an alternative embodiment, referring to fig. 4, the isolated PFC main converter 10 further includes a first main acquisition unit and a second main acquisition unit; the second primary pick-up is connected to the primary power switch Q1 and the first primary pick-up is connected between the first primary pick-up port a2 and the second primary winding 123. The second main collecting port a6 collects the voltage of the main power switch tube Q1 through the second main collecting piece, and the first main collecting port a2 collects the voltage of the second main winding 123 through the first main collecting piece. Optionally, the first main collecting element and the second main collecting element may be a resistor Rdem and a resistor Ri, respectively.
The arrangement of the first main collecting part and the second main collecting part can facilitate the PFC to control and accurately collect required signals, and improve the accuracy of the PFC controller 30 in controlling the main power switch tube Q1.
In an alternative embodiment, referring to fig. 4, the PFC controller 30 includes a main reference voltage source Vref, a main reference sawtooth signal source Vramp1, a first main comparator U1, a second main comparator U2, a third main comparator U3, and a flip-flop U4; flip-flop U4 has an S port, a Q port, and an R port.
The negative input end of the first main comparator U1 is connected with a main feedback port a1, the positive input end of the first main comparator U1 is connected with a main reference voltage source Vref through a main reference voltage port a4, and the output end of the first main comparator U1 is connected with the positive input end of the second main comparator U2; the negative input end of the second main comparator U2 is connected with the second main acquisition port a6, and the output end of the second main comparator U2 is connected with the positive input end of the third main comparator U3; the negative input end of a third main comparator U3 is connected with a main reference sawtooth wave signal source Vramp1 through a main reference sawtooth wave signal port a5, and the output end of the third main comparator U3 is connected with an R port; the Q port is connected to the primary control port a3 and the S port is connected to the first primary acquisition port a 2.
The first master comparator U1 is configured to: comparing the main voltage with the main reference voltage to form a voltage error signal; the second master comparator U2 is configured to: comparing the voltage error signal with the voltage of the main power switch tube to form a comparison result; the third master comparator U3 is configured to: comparing the main reference sawtooth wave signal with the comparison result to form a stop pulse signal; the flip-flop U4 is used to: forming a start pulse signal based on the voltage of the second main winding 123; the stop pulse signal and the start pulse signal are used to control the on and off of the main power switch tube Q1.
Specifically, the first master comparator U1 receives the master voltage Vo1 and the master reference voltage of the master output port, compares the master voltage Vo1 and the master reference voltage of the master output port, and then outputs a voltage error signal to the second master comparator U2. The second main comparator U2 receives the voltage error signal and the voltage of the main power switch Q1, controls the peak current of the main power switch Q1, compares the voltage error signal with the voltage of the main power switch Q1, and outputs the processed voltage error signal to the third main comparator U3. After receiving the processed voltage error signal and the main reference sawtooth wave signal, the third main comparator U3 compares the processed voltage error signal with the main reference sawtooth wave signal, and then outputs the comparison result to the R end of the contactor; the contactor generates a stop pulse signal according to the comparison result, and the stop pulse signal is output to the control end of the main power switch tube Q1 through the Q end of the contactor so as to control the turn-off of the main power switch tube Q1. After receiving the voltage of the second main winding 123 through the S terminal, the contactor generates a start pulse signal by using the voltage of the second main winding 123; then, the start pulse signal is output to the control terminal of the main power switch Q1 through the Q terminal to control the main power switch Q1 to be turned on.
By using the PFC controller 30 with the above structure, the isolated PFC main converter 10 can be precisely controlled, and the isolated PFC main converter is simple to manufacture, low in cost and high in control precision.
In an alternative embodiment, referring to fig. 2 and 3, the isolated AC-DC constant current driver further includes a DC-DC controller 40; the DC-DC auxiliary converter 20 also includes an auxiliary power switch Q2.
Wherein the DC-DC controller 40 comprises an auxiliary feedback port b1, an auxiliary control port b2, an auxiliary reference current port b3, and an auxiliary reference sawtooth signal port b 4; the auxiliary feedback port b1 is connected to the main output port, and the auxiliary control port b2 is connected to the control terminal of the auxiliary power switch Q2.
The main output port outputs a main current after receiving the main voltage and the auxiliary voltage; the total current is transmitted to the secondary feedback port b 1; after the DC-DC controller 40 receives the total current from the auxiliary feedback port b1, the auxiliary reference current from the auxiliary reference current port b3, and the auxiliary reference sawtooth signal from the auxiliary reference sawtooth signal port b4, the total current and the auxiliary reference current are compared to form a voltage error signal; and comparing the voltage error signal with the auxiliary reference sawtooth wave signal to form a control signal, and transmitting the control signal to the control end of the auxiliary power switch tube Q2.
Specifically, the total output port after the auxiliary output port and the main output port are connected in series provides power for the LED light string, so that the voltage provided by the total output port is actually the voltage provided for the LED light string, and therefore, the current fed back by the auxiliary feedback port b1 is actually the current of the LED light string.
Of course, it will be understood by those skilled in the art that the voltage of the LED string is converted from current. Therefore, the control strategy can realize the closed-loop control of the current of the LED lamp string.
In addition, the control strategy of the PFC controller 30 and the control strategy of the DC-DC controller 40 can also realize that the ripples of the main voltage Vo1 of the main output port and the auxiliary voltage Vo2 of the auxiliary output port are reversely superposed and offset each other, thereby reducing the ripple of the total output voltage Vo and reducing the ripple of the current of the LED string.
In detail, the main voltage Vo1 and the auxiliary voltage Vo2 have the purpose of reverse superposition of ripples to reduce or cancel power frequency ripples. The main voltage Vo1 of the main output port has a power frequency ripple, but is connected in series with the auxiliary voltage Vo2 of the auxiliary output port, and the reference signal in the current feedback loop of the DC-DC controller 40 of the DC-DC auxiliary converter 20 is an auxiliary reference current Iref, which is a direct current reference signal.
In addition, the switching frequency of the DC-DC auxiliary converter 20 is much higher than the switching frequency of the isolated PFC main converter 10, so the dynamic response speed of the DC-DC auxiliary converter 20 is very fast, and theoretically, the total current io of the total output port formed by connecting the auxiliary output port and the main output port in series can be equal to Iref in real time, so the total current io is also infinitely close to a direct current value. Meanwhile, the main output port and the auxiliary output port are in series connection, so that the total current of the total output port formed by the series connection of the auxiliary output port and the main output port is equal to the current of the auxiliary output port, and the current of the auxiliary output port is a direct current value, so that the total current is also a direct current value, which is equivalent to the cancellation of power frequency ripples output by the main output port.
As can be seen from the above, the DC-DC auxiliary converter 20 is controlled by a fast loop, and the isolated PFC main converter 10 is controlled by a slow loop. In the application, in order to eliminate the power frequency ripple of the main output port, the main output port and the auxiliary output port are connected in series, so that the current of the main output port, the current of the auxiliary output port and the total current are equal.
The DC-DC controller 40 controls only the output current Ios, and the main voltage Vo1 or the total voltage Vo is controlled by the PFC controller 30. The reason for this is that if the amplitude of the total voltage output is smaller than the amplitude of the voltage for maintaining the normal operation of the load LED, the output DC current required by the load cannot be maintained by controlling the DC-DC controller 40 alone, so that on the one hand, the output voltage required by the load is high enough; on the other hand, when the total output voltage amplitude meets the load requirement, the DC-DC controller 40 maintains an output DC current required by the load, and the fast feedback loop of the DC-DC controller 40 makes the output current infinitely approach the DC value without the power frequency ripple. Therefore, the requirements of load working voltage and current can be met, and power frequency ripples can be eliminated.
In an alternative embodiment, referring to fig. 4, the DC-DC auxiliary converter 20 further includes an auxiliary collecting member. The secondary feedback port b1 collects the total current through the secondary collection element. Optionally, the auxiliary collecting element may be a resistor R3. The secondary collection element may convert the current of the LED string to a voltage that is provided to secondary feedback port b 1.
In an alternative embodiment, referring to fig. 4, the DC-DC controller 40 includes a first auxiliary comparator U5, a second auxiliary comparator U6, an auxiliary reference current source Iref, and an auxiliary reference sawtooth signal source Vramp 2. The negative input end of the first auxiliary comparator U5 is connected with the auxiliary feedback port, the positive input end of the first auxiliary comparator U5 is connected with the auxiliary reference current source Iref through an auxiliary reference current port b3, and the output end of the first auxiliary comparator U5 is connected with the positive input end of the second auxiliary comparator U6; the negative input end of the second auxiliary comparator U6 is connected with an auxiliary reference sawtooth wave signal source Vramp2 through an auxiliary reference sawtooth wave signal port b4, and the output end of the second auxiliary comparator U6 is connected with an auxiliary control port b 2.
The first auxiliary comparator U5 is configured to: comparing the total current with the auxiliary reference current to form a voltage error signal; the second auxiliary comparator U6 is used to: and comparing the voltage error signal with the auxiliary reference sawtooth wave signal to form a control signal, and transmitting the control signal to the control end of the auxiliary power switch tube Q2.
Specifically, the resistor R0 detects the current of the LED string and converts the current into a voltage signal, so that a total current Ios forming feedback is transmitted to the negative input end of the first auxiliary comparator U5, and the first auxiliary comparator U5 compares the total current Ios with the auxiliary reference current after receiving the auxiliary reference current from the auxiliary reference current port b3, and then outputs a voltage error signal formed according to the comparison result to the second auxiliary comparator U6; after receiving the voltage error signal and the auxiliary reference sawtooth wave signal, the second auxiliary comparator U6 compares the voltage error signal with the auxiliary reference sawtooth wave signal, generates a control signal of the auxiliary power switch Q2 according to the comparison result, and outputs the control signal to the control terminal of the auxiliary power switch Q2 to control the on and off of the auxiliary power switch Q2. The DC-DC controller 40 with the structure has the advantages of simple structure, higher control precision and lower cost.
In an alternative embodiment, the isolated PFC main converter 10 comprises a flyback converter or a forward converter; the DC-DC auxiliary converter 20 includes one of a buck converter, a boost converter, a buck-boost converter, a flyback converter, a forward converter, a buck converter, a single-ended primary inductive converter, and a zero-voltage switching converter.
Specifically, the isolated PFC main converter 10 includes a PFC power conversion unit 11, a rectifier diode D5, a rectifier diode Db, a voltage converter 12, and a main power switch Q1. The main power switch tube Q1 also has a body diode DQ1. The main input ports include main input port 1 and main input port 2. The main output port includes a main output port 3 and a main output port 4.
Specifically, referring to fig. 4, the PFC power conversion unit 11 may include an LC filter circuit, a diode full-bridge rectifier circuit, and a filter capacitor Cin. The LC filter circuit comprises a capacitor Cf and an inductor Lf, and two half-bridge circuits of a diode full-bridge rectifying circuit, wherein one half-bridge circuit is formed by connecting diodes D1 and D3 in series, the other half-bridge circuit is formed by connecting diodes D2 and D4 in series, D1 and D2 are located on the upper portion, and D3 and D4 are located on the lower portion. There is a first node between D1 and D3 and a second node between D2 and D4. One end of the inductor Lf is connected with one pole of the alternating current power supply 50 through the main input port 1, and the other end is connected with the first node; one end of the capacitor Cf is connected to the other end of the inductor Lf, and the other end of the capacitor Cf and the second node are both connected to the other pole of the ac power supply 50 through the main input port 2. The filter capacitors Cin and D2 are connected in parallel with the half bridge formed by D4. In addition, the two half bridges and the filter capacitor Cin are connected in parallel and then grounded.
Referring to fig. 4, the following details the structure of the isolated PFC main converter 10 of the flyback converter type:
the first main winding 121, the main power switch Q1 and the resistor Ri are connected in series and then connected in parallel with the filter capacitor Cin. The drain of the main power switch Q1 is connected to the first main winding 121, the source of the main power switch Q1 is connected to the resistor Ri, and the gate of the main power switch Q1 is connected to the Q terminal of the flip-flop U4 via the second main sampling port a 6. A rectifier diode D5 is connected between the first auxiliary winding 122 and the main output port. The second main winding 123 is connected to the first main acquisition port through a resistor Rdem; the rectifier diode Db is connected between the second auxiliary winding 124 and the auxiliary input port 5.
The DC-DC auxiliary converter 20 includes an auxiliary power switch Q2, an inductor L2 (or transformer T2), and a rectifier diode D7. Wherein the auxiliary input ports comprise an auxiliary input port 5 and an auxiliary input port 6. The auxiliary output ports include an auxiliary output port 7 and an auxiliary output port 8. The auxiliary power switch tube Q2 also has a body diode DQ2
Referring to fig. 4, the construction of the buck converter type DC-DC auxiliary converter 20 is described in detail below:
the source of the auxiliary power switch Q2 is connected to one end of the inductor L2, the drain is connected to the auxiliary input port 5, and the gate is connected to the output of the second auxiliary comparator U6. The other end of the inductor L2 is connected to the auxiliary output port 7, one end of the rectifier diode D7 is connected between the source of the auxiliary power switch Q2 and one end of the inductor L2, and the other end of the rectifier diode D7 is connected between the auxiliary input port 6 and the auxiliary output port 8.
Referring to fig. 5, the constitution of the boost converter type DC-DC auxiliary converter 20 is described in detail below:
one end of the inductor L2 is connected to the auxiliary input port 5, and the other end is connected to one end of the rectifier diode D7. The other end of the rectifying diode D7 is connected to the auxiliary output port 7. The source of the auxiliary power switch Q2 is connected between the auxiliary input port 6 and the auxiliary output port 8, the drain is connected between the inductor L2 and the rectifier diode D7, and the gate is connected to the output of the second auxiliary comparator U6.
Referring to fig. 6, the following details the structure of the buck-boost converter type DC-DC auxiliary converter 20:
the source of the auxiliary power switch Q2 is connected to the auxiliary output port 8, the drain is connected to the auxiliary input port 5, and the gate is connected to the output of the second auxiliary comparator U6. The rectifier diode D7 is connected between the auxiliary input port 6 and the auxiliary output port 7. One end of the inductor L2 is connected between the source of the auxiliary power switch Q2 and the auxiliary output port 8, and the other end of the inductor L2 is connected between the auxiliary input port 6 and the rectifier diode D7.
Referring to fig. 7, the construction of the negative buck converter type DC-DC auxiliary converter 20 is described in detail below:
the source of the auxiliary power switch Q2 is connected to one end of the inductor L2, the drain is connected to the auxiliary input port 5, and the gate is connected to the output of the second auxiliary comparator U6. The other end of the inductor L2 is connected to the auxiliary output port 7. One end of the rectifier diode is connected between the auxiliary input port 6 and the auxiliary output port 8, and the other end is connected between the source of the auxiliary power switch tube Q2 and one end of the inductor L2.
Referring to fig. 8, the following details the configuration of the flyback converter type DC-DC auxiliary converter 20:
the transformer T2 comprises a first winding and a second winding, wherein one end of the first winding is connected with the auxiliary input port 5, and the other end of the first winding is connected with the drain electrode of the auxiliary power switch tube Q2; the source electrode of the auxiliary power switch tube Q2 is connected with the auxiliary input port 6, and the grid electrode of the auxiliary power switch tube Q2 is connected with the output end of the second auxiliary comparator U6; one end of the second winding of the transformer T2 is connected to the rectifier diode D7, the other end of the rectifier diode D7 is connected to the auxiliary output port 7, and the other end of the second winding is connected to the auxiliary output port 8.
In addition, the circuit is also provided with filter capacitors Co1, Cb and Co2, wherein the filter capacitor Co1 is connected between the main input ports 3 and 4 for filtering the output voltage of the main input ports. The filter capacitor Cb is connected between the auxiliary input ports 5 and 6, and filters the input voltage at the auxiliary input ports. The filter capacitor Co2 is connected between the auxiliary output ports 7 and 8 to filter the output voltage at the auxiliary output ports.
Embodiments of the present application further provide an LED lighting device, which includes the isolated AC-DC constant current driver provided in any optional embodiment of the present application.
The foregoing detailed description of the embodiments of the present application has been presented to illustrate the principles and implementations of the present application and, therefore, the above description of the embodiments may be used to help understand the method and the core concepts of the present application.

Claims (10)

1. An isolated AC-DC constant current driver, comprising: isolating the PFC main converter and the DC-DC auxiliary converter;
the isolated PFC main converter comprises a PFC power conversion unit, a voltage converter and a main output port, wherein the voltage converter comprises a first main winding, a second main winding, a first auxiliary winding and a second auxiliary winding; the first main winding and the first auxiliary winding are mutually induced, the second main winding and the second auxiliary winding are mutually induced, and the DC-DC auxiliary converter comprises an auxiliary input port and an auxiliary output port;
the output end of the PFC power conversion unit is connected with the first main winding; the first auxiliary winding is connected with the main output port; the second auxiliary winding is connected with the auxiliary input port; the auxiliary output port and the main output port are connected in series to form a total output port;
after the voltage converter receives the direct current from the PFC power conversion unit: converting a main voltage through the first main winding and the first auxiliary winding, and outputting the main voltage to the main output port, wherein the main output port transmits the main voltage to the main output port; converting an auxiliary voltage through the second main winding and the second auxiliary winding, and outputting the auxiliary voltage to the auxiliary input port; and after receiving the auxiliary voltage from the auxiliary input port, the DC-DC auxiliary converter processes the auxiliary voltage and outputs the processed auxiliary voltage to the auxiliary output port, and the auxiliary output port transmits the auxiliary voltage to the total output port.
2. The isolated AC-DC constant current driver of claim 1, further comprising: a PFC controller; the isolated PFC main converter further comprises: a main power switch tube;
the main power switch tube is connected with the first main winding;
the PFC controller comprises a main feedback port, a first main acquisition port, a main control port, a main reference voltage port and a main reference sawtooth wave signal port; the main feedback port is connected with the main output port, the first main acquisition port is connected with the second main winding, and the main control port is connected with the control end of the main power switch tube;
the main output port transmits the main voltage to the main feedback port, and the PFC controller receives the main voltage from the main feedback port, the voltage of the second main winding from the first main acquisition port, the main reference voltage from the main reference voltage port, and a main reference sawtooth signal from the main reference sawtooth signal port; comparing the main voltage with the main reference voltage to form a voltage error signal; comparing the voltage error signal with the main reference sawtooth wave signal to form a stop pulse signal; forming a start pulse signal based on a voltage of the second main winding; and controlling the on and off of the main power switch tube by using the stop pulse signal and the start pulse signal.
3. The isolated AC-DC constant current driver of claim 2, wherein the PFC controller further comprises a second main acquisition port; the second main acquisition port is connected with the main power switch tube;
the PFC controller also receives the voltage of the main power switch tube from the second main acquisition port;
the comparing the voltage error signal and the main reference sawtooth wave signal to form a stop pulse signal includes: and comparing the voltage error signal with the voltage of the main power switch tube to form a comparison result, and comparing the main reference sawtooth wave signal with the comparison result to form a stop pulse signal.
4. The isolated AC-DC constant current driver of claim 3, wherein the isolated PFC main converter further comprises: a first main collecting part and a second main collecting part; the first main acquisition part is connected between the first main acquisition port and the second main winding; the second main collecting part is connected with the main power switch tube;
the first main collecting port collects the voltage of the second main winding through the first main collecting part, and the second main collecting port collects the voltage of the main power switch tube through the second main collecting part.
5. The isolated AC-DC constant current driver of claim 3, wherein the PFC controller comprises a main reference voltage source, a main reference sawtooth signal source, a first main comparator, a second main comparator, a third main comparator and a flip-flop; the flip-flop is provided with an S port, a Q port and an R port;
a negative input terminal of the first master comparator is connected to the master feedback port, a positive input terminal of the first master comparator is connected to the master reference voltage source through the master reference voltage port, and an output terminal of the first master comparator is connected to a positive input terminal of the second master comparator; the negative input end of the second main comparator is connected with the second main acquisition port, and the output end of the second main comparator is connected with the positive input end of the third main comparator; the negative input end of the third main comparator is connected with the main reference sawtooth wave signal source through the main reference sawtooth wave signal port, and the output end of the third main comparator is connected with the R port; the Q port is connected with the main control port, and the S port is connected with the first main acquisition port;
the first master comparator is to: comparing the main voltage with the main reference voltage to form a voltage error signal; the second master comparator is to: comparing the voltage error signal with the voltage of the main power switch tube to form a comparison result; the third master comparator is to: comparing the main reference sawtooth wave signal with the comparison result to form a stop pulse signal; the trigger is used for: forming a start pulse signal based on a voltage of the second main winding; and controlling the on and off of the main power switch tube by using the stop pulse signal and the start pulse signal.
6. The isolated AC-DC constant current driver of claim 1, further comprising: a DC-DC controller; the DC-DC auxiliary converter further includes: an auxiliary power switch tube;
the DC-DC controller comprises an auxiliary feedback port, an auxiliary control port, an auxiliary reference current port and an auxiliary reference sawtooth wave signal port; the auxiliary feedback port is connected with the main output port, and the auxiliary control port is connected with the control end of the auxiliary power switch tube;
the total output port outputs total current after receiving the main voltage and the auxiliary voltage; the total current is transmitted to the secondary feedback port; after the DC-DC controller receives the total current from the auxiliary feedback port, the auxiliary reference current from the auxiliary reference current port and the auxiliary reference sawtooth wave signal from the auxiliary reference sawtooth wave signal port, comparing the total current with the auxiliary reference current to form a voltage error signal; and comparing the voltage error signal with the auxiliary reference sawtooth wave signal to form a control signal, and transmitting the control signal to the control end of the auxiliary power switch tube.
7. The isolated AC-DC constant current driver of claim 6, wherein the DC-DC auxiliary converter further comprises: an auxiliary collecting member;
the auxiliary feedback port collects the total current through the auxiliary collecting member.
8. The isolated AC-DC constant current driver of claim 6, wherein the DC-DC controller comprises: the auxiliary reference current source comprises a first auxiliary comparator, a second auxiliary comparator, an auxiliary reference current source and an auxiliary reference sawtooth wave signal source;
the negative input end of the first auxiliary comparator is connected with the auxiliary feedback port, the positive input end of the first auxiliary comparator is connected with the auxiliary reference current source through the auxiliary reference current port, and the output end of the first auxiliary comparator is connected with the positive input end of the second auxiliary comparator; the negative input end of the second auxiliary comparator is connected with the auxiliary reference sawtooth wave signal source through the auxiliary reference sawtooth wave signal port, and the output end of the second auxiliary comparator is connected with the auxiliary control port;
the first auxiliary comparator is to: comparing the total current with the auxiliary reference current to form a voltage error signal; the second auxiliary comparator is to: and comparing the voltage error signal with the auxiliary reference sawtooth wave signal to form a control signal, and transmitting the control signal to the control end of the auxiliary power switch tube.
9. The isolated AC-DC constant current driver of any one of claims 1 to 8, wherein the isolated PFC main converter comprises a flyback converter or a forward converter; the DC-DC auxiliary converter comprises one of a buck converter, a boost converter, a buck-boost converter, a flyback converter, a forward converter, a Cuk converter, a single-ended primary inductance type converter and a zero-voltage switch converter.
10. An LED lighting device comprising the isolated AC-DC constant current driver of any one of claims 1 to 9.
CN202120234953.XU 2021-01-27 2021-01-27 Isolated AC-DC constant current driver and LED lighting equipment Withdrawn - After Issue CN214627432U (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112770451A (en) * 2021-01-27 2021-05-07 茂硕电源科技股份有限公司 Isolated AC-DC constant current driver and LED lighting equipment

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112770451A (en) * 2021-01-27 2021-05-07 茂硕电源科技股份有限公司 Isolated AC-DC constant current driver and LED lighting equipment
CN112770451B (en) * 2021-01-27 2024-06-07 茂硕电源科技股份有限公司 Isolated AC-DC constant current driver and LED lighting equipment

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