CN208434144U - LED drive circuit and lamps and lanterns including the LED drive circuit - Google Patents
LED drive circuit and lamps and lanterns including the LED drive circuit Download PDFInfo
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- CN208434144U CN208434144U CN201721280625.3U CN201721280625U CN208434144U CN 208434144 U CN208434144 U CN 208434144U CN 201721280625 U CN201721280625 U CN 201721280625U CN 208434144 U CN208434144 U CN 208434144U
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
- Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
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Abstract
This disclosure relates to LED drive circuit and the lamps and lanterns including the LED drive circuit.The utility model provides a kind of for driving the piecewise linearity driving circuit of LED, including power switch (M2), being connected to the output end and being used to connect with LED load electric current with control from the supply voltage, the described output end output；Control loop (Q1, R4, R5), for detecting the electric current for flowing through the power switch (M2), and the impedance for controlling the power switch (M2) makes the detection electric current meet reference current；It is characterized in that, the control loop includes: linear circuit (R4, R5), it is connected to the input terminal, within the scope of the acceptable specified mean value of the supply voltage, according to the one-to-one linear relationship of each mean value, instantaneous amplitude of the supply voltage in whole cycle is converted into the reference current with the constant linear relationship fairly linearly.
Description
Technical field
The embodiments of the present invention relate generally to lighting area, and relate more specifically to a kind of LED drive circuit,
For lamps and lanterns.
Background technique
Piecewise linearity drives (Tapped Linear Driver) circuit to directly drive LED using sinusoidal mains, without
Want complicated Switching Power Supply.The technology is due to the advantages such as at low cost, power is big, and application field is increasing, such as at present at family
There is good application prospect in the fields such as outer illumination.
A kind of piecewise linearity driving based on integrated circuit (IC) being currently known is as shown in Figure 1.Mean value is 230VRMS's
After alternating current is changed into direct current signal by rectifier bridge, three sections of LED are driven by piecewise linearity driving.From top to bottom, first segment
LED is by a switch mosfet Q3 connected in parallel and first Integrated circuit IC TPS92411 control；Second segment LED by
Second Integrated circuit IC TPS92411 control connected in parallel；Third section LED is by third Integrated circuit IC connected in parallel
TPS92411 control.The linear switch Q1 that is connected in series through of three sections of LED is connected to ground/connect back to rectifier bridge.The operation of circuit
Principle is: each IC detects the voltage at its end VS, cathode (and anode of the next LED segment) phase at the end VS and corresponding LED segment
Even.The voltage at the end VS is compared with a setting voltage inside IC, if the voltage is lower than the setting voltage, the switch inside IC
Conducting is short-circuit by corresponding LED segment；If the voltage is higher than the setting voltage, the switch inside IC is disconnected, and corresponding LED segment is entered electricity
Pressure is driven.The setting voltage of third IC is minimum, gradually rises from the bottom up, first highest.Workflow is:
When alternating current period zero passage starts, all IC are by LED segment short circuit.
As line voltage increases, voltage is applied on linear switch Q1, make third IC the end VS voltage increase until
Its setting voltage, third IC is begun breaking at this time, and third section LED starts to shine.
As line voltage continues to increase, the end the VS voltage of second IC is increased to its setting voltage, and second at this time
IC is begun breaking, and second segment LED starts to shine.Simultaneously as voltage drop is produced on second segment LED, the end VS of most lower IC
Voltage is lower instead, and third IC is begun to turn at this time, and third section LED is short-circuited.
As line voltage continues to increase, increased voltage is applied to again on linear switch Q1, makes the end VS of third IC
Voltage is by increasing until setting voltage, third IC is begun breaking at this time, and third section LED starts to shine again.In the process
Two sections of LED still keep luminous.
As line voltage continues to increase, the end the VS voltage of first IC is increased to setting voltage, and first IC is opened at this time
Begin to disconnect, first segment LED starts to shine.Simultaneously as voltage drop is produced on first segment LED, second and third IC
The end VS voltage is lower instead, and second and third IC begins to turn at this time, and second segment and third section LED are short-circuited.
As line voltage continues to increase, voltage is applied on linear switch Q1, makes the end the VS voltage liter of the IC of third
Height is until setting voltage, and third IC is begun breaking at this time, and third section LED starts to shine.First segment LED is still protected in the process
It holds luminous.
As line voltage continues to increase, the end the VS voltage of second IC is increased to setting voltage, and second IC is opened at this time
Begin to disconnect, second segment LED starts to shine.Simultaneously as voltage drop is produced on second segment LED, the end the VS voltage of most lower IC
It is lower instead, third IC is begun to turn at this time, and third section LED is short-circuited.First segment LED is still kept luminous in the process.
As line voltage continues to increase, increased voltage is applied to again on linear switch Q1, makes the end VS of third IC
Voltage is by increasing until setting voltage, third IC is begun breaking at this time, and third section LED starts to shine again.In the process
One section and second segment LED still keeps luminous.
Line voltage reaches peak and begins to decline later, and the operation of each IC is opposite with line voltage uphill process.No
It repeats again.More specifically description may refer to TPS92411 technical manual " TPS92411x be used for low ripple electric current
Light emitting diode (LED) carry out the float switch that offline AC linear directly drives " (Copyright2015,Texas
Instruments Incorporated)。
High power driving has very strict requirements to total harmonic distortion (THD), i.e., it is required that input current is close as far as possible
It is similar to sinusoidal (similar to line voltage shape).In order to realize the purpose, the base stage of MOSFET Q1 is connected to by the Europe 1M resistance
Line voltage after rectification, base voltage is also an approximate sinusoidal voltage, therefore the current signal that MOSFET Q1 is provided is also
Near sinusoidal shape has acceptable total harmonic distortion.
For when inputting the different mean values of alternating current, it is desirable to provide relatively stable output power, and cannot be because of
The raising of input voltage and excessively increasing output power (Serial regulation or line regulation).Segmented line in Fig. 1
Property driving this function is realized using triode Q2 and accessory circuit.Specifically, there is the input of higher mean value for some
Voltage, when the instantaneous amplitude of input voltage in the period is more than by the Europe bleeder circuit 442K and the Europe 249K and 68V Zener diode
After some threshold value of setting, 68V Zener diode will be breakdown, and additional electric current is by injection triode Q2, so that MOSFET
Current reduction provided by Q1.With continuing growing for instantaneous amplitude, electric current provided by MOSFET Q1 is even lower.Such as Fig. 2
Shown, electric current is initially sinusoidal shape, consistent with input voltage shape；After input voltage reaches certain threshold value, electric current is instead
It begins to decline, input voltage is higher, and electric current is recessed more significant.Although this recessed electric current makes power keep stablizing, still
It is degrading total harmonic distortion.
The another drawback of existing design is, other than third section, controls the integrated circuit of other several sections of LED all
It is to be arranged floatingly.And when the voltage of first segment LED is higher than 100 volts, the IC of existing design needs additional MOSFET
Another reason for Q3 series connection with it controls first segment LED together, adds this additional MOSFET Q3 is to need to pass through
The surge of 6K V detects.These settings bring some problems: the supply voltage VIN of first IC needs in first segment LED extremely
It could be provided after few a part conducting, therefore lead to first IC job insecurity in startup stage.Also, VIN voltage is also
First IC provides aforementioned setting voltage, and being arranged floatingly for this IC causes setting voltage appearance unstable.Additional
MOSFET Q3 also leads to additional voltage drop, so that the control of first segment is unstable.Due in the design, the work of each IC
It is to be mutually related, therefore entire circuit also will appear unstable or concussion.
Utility model content
To solve the problems, such as total harmonic distortion, the design of the first aspect of the utility model is, avoids using recessed
The reference current of shape, but fully provided and input voltage phase by constant linear relationship in the whole cycle of input voltage
The reference current of pass, and for the input voltage of different mean values, there is one-to-one linear relationship.Due to the ginseng in whole cycle
It examines electric current and input voltage is constant linear relationship, therefore when LED drives and provides input/output electric current, which can be with
It is consistent with the shape of input voltage, there is lower total harmonic distortion.Preferably, the linear relationship and the mean value of input voltage are in
Opposite direction variation keeps the ratio of the linear relationship corresponding to higher mean value input voltage smaller and makes reference current smaller,
Input current is reduced in the case where high-line input voltage mean value, stablizing even reduces output power.
The first aspect of the utility model provides a kind of LED drive circuit, comprising: input terminal, it is instantaneous for receiving
The supply voltage that amplitude changes over time；Output end, for being connected to LED load；It is moved according to the instantaneous amplitude of the alternating current
State adjusts the switching circuit of the quantity of be connected to LED load, so that the conducting voltage for the LED load being connected to and institute
State alternating current instantaneous amplitude matching, wherein the switching circuit include it is with the LED load, concatenated multiple sections it is in parallel one by one
Switch；Power switch is connected to the output end and is used to connect with the LED load, comes from the supply voltage with control
, the electric current of output end output；Control loop for detecting the electric current for flowing through the power switch, and controls the function
The impedance of rate switch makes the detection electric current meet reference current；It is characterized in that, the control loop includes: linear circuit,
It is connected to the input terminal, within the scope of the acceptable specified mean value of the supply voltage, is corresponded according to each mean value
Linear relationship, instantaneous amplitude of the supply voltage in whole cycle is turned fairly linearly with the constant linear relationship
It is changed to the reference current.
In this aspect, within the scope of acceptable specified mean value, by instantaneous amplitude of the supply voltage in whole cycle with
Constant linear relationship is converted to reference current fairly linearly.Therefore within the scope of acceptable specified mean value, whole cycle
In, it is constant linear relationship between provided input current and input supply voltage, reduces total harmonic wave of input current
Distortion.Here the constant supply voltage referred to for giving mean value, linear relationship are in the whole cycle of supply voltage
Constant.
In a further embodiment, linear circuit includes the partial pressure that first resistor and second resistance are connected in series
Circuit, the control loop include: and the concatenated detection resistance of the power switch；Triode is controlled, collector is connected to
The control electrode of the power switch, base stage is connected to the detection resistance, and collector is connected to the first resistor and second
The tie point of resistance.
In this embodiment, linear relationship is realized by resistor voltage divider circuit, and exports the ratio of electric current and the reference signal
It realizes that circuit is stable to emitter voltage compared with by the base stage for controlling triode, implements also easier.
In a further embodiment, the control electrode of the power switch is connected to institute by driving element
State input terminal.This embodiment offers the driving methods of power switch, and current control is completed yet by aforementioned control loop.
In a further embodiment, further includes: compensation circuit is connected to the input terminal and the linear electricity
Road for detecting the mean value of the supply voltage, and changes the linear relationship according to the variation of the mean value.The embodiment party
Formula provides Serial regulation.And the embodiment changes linear relationship according to different mean values, and the linear relationship being changed exists
It is still constant in input voltage whole cycle, therefore reference current and input current are still in a linear relationship with input voltage,
So total harmonic distortion is lower.
In a further embodiment, the compensation circuit includes: average capacitance, for detecting the power supply electricity
The mean value of pressure；Threshold element, for detecting whether the mean value is more than certain threshold value；Switch, when the mean value is more than the threshold
When value, the intrinsic standoff ratio of the bleeder circuit is controlled.
This embodiment offers the specific implementations of compensation circuit, implement fairly simple.
In a further embodiment, the switch works in linear condition according to the mean value with phase negative side
To the output for controlling the bleeder circuit.In this embodiment, when mean value increases, the output of bleeder circuit is lower, i.e.,
Reference current and output electric current are lower, avoid the output power of LED drive circuit excessively high.
In a further embodiment, the switch includes triode and the emitter for being connected to the triode
3rd resistor.The embodiment provides the switch of linear condition using triode, and cost is relatively low.And subtracted using 3rd resistor
The difference of the amplification factor of few different triodes, facilitates commercialization.
In a further embodiment, the input terminal is used to receive alternating current as the instantaneous amplitude at any time
The supply voltage of variation.The piecewise linearity driver that the embodiment directly drives particularly suitable for use line voltage.
Based on the above, the utility model additionally provides a kind of lamps and lanterns, including LED driving circuit above-mentioned, and by institute
State the LED that LED drive circuit is driven.Preferably, which is outdoor lamp, such as street lamp or floodlight
(floodlighting) the high power lamps tool such as.
The piecewise linearity based entirely on integrated circuit to solve the problems, such as in Fig. 1 drives fluctuation of service, this is practical new
The design of the second aspect of type is, avoids controlling first segment LED using the integrated circuit on floating ground, but use is connected to
The circuit of the power ground of input terminal and input terminal controls first segment LED.The control circuit of first segment LED in this way is no longer dependent on
First segment LED and shake.
The second aspect of the utility model provides a kind of LED drive circuit, comprising: input terminal, it is instantaneous for receiving
The supply voltage that amplitude changes over time；Output end, for being connected to LED load；It is moved according to the instantaneous amplitude of the alternating current
State adjusts the switching circuit of the quantity of be connected to LED load, so that the conducting voltage for the LED load being connected to and institute
State alternating current instantaneous amplitude matching, wherein the switching circuit include it is with the LED load, concatenated multiple sections it is in parallel one by one
Switch, shown switching circuit include:
First switch circuit, it is in parallel with the first segment in the LED load；
Second switch circuit, it is in parallel with the second segment in the LED load, wherein the conducting voltage of the second segment is less than
The conducting voltage of the first segment；
Wherein, the second switch circuit includes the second integrated circuit, and second integrated circuit includes and described second
The connected voltage detection terminal of the cathode of section, and will be described for being opened when the voltage of the voltage detection terminal is lower than second threshold
Second segment short circuit, disconnects when the voltage of the voltage detection terminal is higher than the second threshold and opens the second segment；
It is characterized in that, the first switch circuit includes:
Voltage detecting circuit is connected to the power ground of the input terminal and input terminal, for detecting the electricity of the input terminal
Pressure；
Comparison circuit, voltage and first threshold for the input terminal；
Control circuit, it is for being opened when the voltage of the input terminal is less than the first threshold that the first segment is short
Road disconnects when the voltage of the input terminal is greater than the first threshold and opens the first segment.
Since the voltage detecting circuit in first switch circuit is attached to the power ground of the input terminal and input terminal, institute
It is relatively stable with the triggering, concussion will not be generated, further the integrated circuit of other section of LED will not be caused to shake.
In one preferred embodiment, second integrated circuit includes TPS92411 or TPS92411P chip,
The conducting voltage of the second segment is less than 100 volts, and the conducting voltage of the first segment is greater than 100 volts.
This embodiment offers the supports to the piecewise linearity driving based on TPS92411 integrated circuit, will not cause the
The TPS92411 chip concussion of two sections of LED.
In one preferred embodiment, the anode of the first segment is connected to the anode of the input terminal, and described
The cathode of anode and the second segment that one section of cathode is connected to the second segment is couple to the power supply of the input terminal
Ground.This embodiment offers drive that typical circuit when LED is driven to be arranged using piecewise linearity.
In one preferred embodiment, the voltage detecting circuit includes bleeder circuit, and the comparison circuit includes
Zener diode, the control circuit include: the first switch in parallel with the first segment；With the control electrode of the first switch
Connected switching group, the switching group are connected to the input terminal and the comparison circuit, for by the voltage of the input terminal
It biases and the first switch is connected, and triggered and disconnected the first switch by the comparison circuit.
This embodiment offers the specific implementations of first switch circuit, wherein using two pole of bleeder circuit and Zener
Pipe circuit realizes voltage acquisition and detection, and Comparision is stablized, and facilitate realization.
In one preferred embodiment, shown switching circuit further include:
Third switching circuit, it is in parallel with the third section in the LED load, wherein the conducting voltage of the third section is less than
The conducting voltage of the second segment；
Wherein, the third switching circuit includes third integrated circuit, and the third integrated circuit includes and the third
The connected voltage detection terminal of the cathode of section, and will be described for being opened when the voltage of the voltage detection terminal is lower than third threshold value
Third section short circuit, disconnects when the voltage of the voltage detection terminal is higher than the third threshold value and opens the third section, described
Second integrated circuit includes TPS92411 or TPS92411P chip, and the conducting voltage of the third section is less than 100 volts；
The cathode of the second segment is couple to the anode of the third section, and the cathode of the third section is connected to the input
The power ground at end.
This embodiment offers the realizations of the piecewise linearity of three-stage driving.It is appreciated that also can be used four sections and
Above piecewise linearity driving, these implementations equally fall into the coverage area of aforementioned two sections and three sections realizations.
Preferably, the first switch circuit includes discrete elements, and cost is relatively low.
In one preferred embodiment, since the conducting voltage of second segment or third section LED have certain tolerance, it is
Make the work of first segment LED and the work of second segment and third section LED mutually coordinated, which further includes mending
Circuit is repaid, the anode and the voltage detecting circuit of the second segment or the third section are connected to, to detect the second segment
With the conducting voltage of the third section or the conducting voltage of the third section, and according to the conducting voltage detected come with opposite
The voltage of the detected input terminal of direction adjustment.
If the conducting voltage of second segment or third section is high, need first segment LED just open-minded after higher voltage；It is on the contrary
?.Therefore in the embodiment, the voltage of the detected input terminal is adjusted in the opposite direction according to the conducting voltage,
When conducting voltage is high, the input terminal voltage detected is reduced, so that needing higher input terminal voltage that can just make first segment LED
It is open-minded.
In one preferred embodiment, the input terminal becomes for receiving alternating current as the instantaneous amplitude at any time
The supply voltage of change.The embodiment is suitable for the piecewise linearity driving that line voltage is directly powered, and has a wide range of applications.
The utility model additionally provides a kind of lamps and lanterns, including the LED driving circuit according to aforementioned second aspect, and by institute
State the LED that LED drive circuit is driven.Preferably, which is outdoor lamp, such as street lamp or floodlight
(floodlighting) the high power lamps tool such as.
The LED driving being composed of aforementioned first aspect and second aspect is provided in terms of the third of the utility model
Circuit, comprising: input terminal, the supply voltage changed over time for receiving instantaneous amplitude；Output end, it is negative for being connected to LED
It carries；The switching circuit for adjusting the quantity of be connected to LED load come dynamic according to the instantaneous amplitude of the alternating current, so that company of institute
The conducting voltage for the LED load being connected to is matched with the instantaneous amplitude of the alternating current, and wherein the switching circuit includes negative with the LED
Carrying, concatenated multiple sections in parallel switches one by one；Power switch is connected to the output end and is used for and the LED load
Series connection, to control the electric current from the supply voltage, the described output end output；Control loop flows through described for detection
The electric current of power switch, and the impedance for controlling the power switch makes the detection electric current meet reference current；It is described to control back
Road includes: linear circuit, is connected to the input terminal, within the scope of the acceptable specified mean value of the supply voltage, according to
With the one-to-one linear relationship of each mean value, by instantaneous amplitude of the supply voltage in whole cycle with constant linear pass
It is to be converted to the reference current fairly linearly；Wherein the switching circuit includes with the LED load, concatenated multiple
The switch of Duan Yiyi parallel connection, shown switching circuit includes: first switch circuit, in parallel with the first segment in the LED load；The
Two switching circuits, it is in parallel with the second segment in the LED load, wherein the conducting voltage of the second segment is less than the first segment
Conducting voltage；Wherein, the second switch circuit includes the second integrated circuit, and second integrated circuit includes and described the
The connected voltage detection terminal of two sections of cathode, and for opening when the voltage of the voltage detection terminal is lower than second threshold by institute
Second segment short circuit is stated, is disconnected when the voltage of the voltage detection terminal is higher than the second threshold and opens the second segment；Institute
Stating first switch circuit includes: voltage detecting circuit, is connected to the power ground of the input terminal and input terminal, described for detecting
The voltage of input terminal；Comparison circuit, voltage and first threshold for the input terminal；Control circuit, for when described
The voltage of input terminal is opened when being less than the first threshold by the first segment short circuit, when the voltage of the input terminal is greater than described
It is disconnected when first threshold and opens the first segment.
The advantages of reference the drawings and the specific embodiments, the embodiments of the present invention, will be by the general technology of this field
Understood.
Detailed description of the invention
Fig. 1 shows a kind of existing piecewise linearity driving；
Fig. 2 is that the piecewise linearity of Fig. 1 drives for the input/output current waveform under different mean value input voltages；
Fig. 3 is the embodiment according to the utility model first aspect；
Fig. 4 is embodiment in Fig. 3 for the input/output current waveform under different mean value input voltages；
Fig. 5 is the embodiment according to the utility model the second aspect.
Specific embodiment
The principle of the disclosure is illustrated now with reference to various exemplary embodiments shown in the drawings.It should manage
Solution, the descriptions of these embodiments is just to better understood when those skilled in the art and further realize this public affairs
It opens, and is not intended to limit the scope of the present disclosure in any way.It should be noted that can make in figure under possibilities
With appended drawing reference similar or identical, and appended drawing reference similar or identical can indicate function similar or identical.Ability
The technical staff in domain will readily appreciate that from the following description, the substitution of structures and methods illustrated here is implemented
Example can be used without departing from by the principles of the present invention described herein.
Fig. 3 is according to the embodiment of the utility model first aspect, including input terminal, for receiving instantaneous amplitude at any time
Between the supply voltage V1 that changes, preferably also comprise the rectifier bridge being made of diode DB1-4, the bus of rectifier bridge output here
Voltage Vbus is exactly the supply voltage V1 after taking absolute value substantially.Output end, for being connected to LED load.According to the alternating current
Instantaneous amplitude carry out the switching circuit that dynamic adjusts the quantity of be connected to LED load so that the LED load that is connected to
Conducting voltage is matched with the instantaneous amplitude of the alternating current, and wherein the switching circuit includes with the LED load, concatenated multiple
The switch of Duan Yiyi parallel connection.The switching circuit and LED load are by briefly paintings LED3 in Fig. 3.Power switch M2, is connected to
The output end simultaneously is used to connect with the LED load, to control the electricity from the supply voltage, the described output end output
Stream.Control loop R1, Q1, R4, R5 for detecting the electric current for flowing through the power switch M2, and control the power switch
The impedance of M2 makes the detection electric current meet reference current；It is characterized in that, the control loop includes: linear circuit R4, R5,
It is connected to the input terminal, within the scope of the acceptable specified mean value of the supply voltage, is corresponded according to each mean value
Linear relationship, instantaneous amplitude of the supply voltage in whole cycle is converted fairly linearly with constant linear relationship
For the reference current.
Preferably, linear circuit is the bleeder circuit of first resistor R4 and second resistance R5 composition, then has following equation
Vref=Vbus*R5/ (R4+R5)
And detection resistance R1 is connected between the source electrode and power ground of MOSFET M2 for detection stream overpower switch M2's
Electric current I, then have following equation
VR1=I*R1
R3 is a current-limiting resistance, and voltage VR1 is connected to the base stage of triode Q1 by it.
For triode Q1, its collector is connected to the grid of power switch M2, and base stage is connected to the detection
Resistance R1, and collector is connected to the tie point of first resistor R4 and second resistance R5.The base emitter voltage of triode is
VQ1be, then
Work as VR1>=Vref+VQ1beWhen, triode enters amplification mode, the grid voltage of power switch M2 dragged down, thus
The electric current I for flowing through M2 is reduced, and then reduces VR1.Under stability state, the electric current I for flowing through M2 should be with Vref+VQ1beIt is linear,
Wherein due to VQ1beIt is smaller, so it should be with V to electric current IrefBetween the not substantive contribution of relationship, therefore can be approximate
Think electric current I and VrefBetween have linear relationship, in other words electric current I should be consistent with reference current, the reference current be Vref/
R1.The control loop includes: linear circuit, is connected to the input terminal, in the acceptable specified equal of the supply voltage
Be worth range in, according to the one-to-one linear relationship of each mean value, by instantaneous amplitude of the supply voltage in whole cycle
The reference current is converted to fairly linearly with the constant linear relationship.The linear relationship is covered such as triode Q1
Base emitter voltage the case where taking into account.
Therefore, as the amplitude of input voltage signal is when in whole cycle with the variation of such as sinusoidal shape, VrefAccording to than
Example R5/ (R4+R5) is changed with same shape, and electric current I is according to VrefIt is changed.Then electric current should have the complete of substance
Sinusoidal shape, rather than there is the depressed section for leading to total harmonic distortion as the prior art shown in Fig. 2.
Also, as shown in figure 3, the LED drive circuit further includes compensation circuit, it is connected to the input terminal and described linear
Circuit for detecting the mean value of the supply voltage, and changes the linear relationship according to the variation of the mean value.Specifically
Ground, the compensation circuit includes: average capacitance C2, for detecting the mean value of the supply voltage；Threshold element Z2, for detecting
Whether the mean value is more than certain threshold value；Switch Q2 controls point of the bleeder circuit when the mean value is more than the threshold value
Pressure ratio.
Specifically, the switch Q2 works according to the mean value controls described point in linear condition in the opposite direction
The output of volt circuit.For example, working as by bleeder circuit R6 and R7 partial pressure and big by the mean value Vp of the C2 input voltage detected
In Zener diode Z2 breakdown voltage and triode Q2 base-collector voltage when, triode Q2 be connected and reduce aforementioned
The impedance of second resistance R5 in bleeder circuit R4, R5, correspondingly reduce Vref under the input voltage of the mean value and
Input/output electric current I.The mean value of input voltage is bigger, and the impedance of triode Q2 is lower, and bleeder circuit R4, R5 output are lower, because
This input/output electric current is lower.It is worth noting that, bleeder circuit R4, R5 are still in the whole cycle of the input voltage
It is a linear circuit, therefore electric current still has substantive complete sinusoidal shape, only current amplitude is relative to lower equal
Current amplitude under the input voltage of value can reduce.As shown in figure 4, the leftmost side be input voltage mean value be 220V when input/
Output current wave, centre be input voltage mean value be 240V when input/output current waveform, the rightmost side is that input voltage is equal
Input/output current waveform when value is 264V.Straight line between waveform peak shows the size between different input currents
Relationship.It is lost it is worth noting that, piecewise linearity driving may generate some input/output electric currents during block switch
Very, but this sinusoidal shape for having no effect on reference current, the sinusoidal shape of input/output electric current substance is nor affected on.
The following table 1 shows the input power under the input voltage of different mean values, input current, PFC (capability correction because
Son) and THD (total harmonic distortion).
Table 1
In table 1, input power is in changing inversely with the variation of the mean value of input voltage.It is appreciated that at it
In his embodiment, it can also get off input power is constant.
Fig. 5 shows the circuit diagram of the embodiment according to the utility model the second aspect.Wherein power switch can be with
The MOSFET M2 in Fig. 3, and may further include first aspect in Fig. 3 for modulating input/output electricity
The control loop and linear circuit of stream, the control loop and linear current are not shown in Figure 5.
As shown in figure 5, the LED drive circuit includes input terminal, the power supply electricity changed over time for receiving instantaneous amplitude
Press Vin, e.g. alternating current.Output end, for being connected to LED load.Institute is dynamically adjusted according to the instantaneous amplitude of the alternating current
The switching circuit of the quantity for the LED load being connected to, so that the wink of the conducting voltage for the LED load being connected to and the alternating current
When amplitude match, wherein the switching circuit includes with the LED load, concatenated multiple sections switches in parallel one by one, shown
Switching circuit includes:
First switch circuit, it is in parallel with the first segment LED1 in the LED load；
Second switch circuit, it is in parallel with the second segment LED2 in the LED load, wherein the conducting voltage of the second segment
Less than the conducting voltage of the first segment；
Wherein, the second switch circuit includes the second Integrated circuit IC 2, and second integrated circuit includes and described the
The connected voltage detection terminal of two sections of cathode, and for opening when the voltage of the voltage detection terminal is lower than second threshold by institute
Second segment short circuit is stated, is disconnected when the voltage of the voltage detection terminal is higher than the second threshold and opens the second segment.The
The terminals of two Integrated circuit IC 2 connects and its can refer in Fig. 1 the terminal of second IC from top to bottom with the connection relationship of LED2
Connection and its connection relationship with corresponding LED, operation principles be also it is similar, details are not described herein.
Although illustrating only a LED in Fig. 3, first segment, second segment and third section also all illustrate only one in Fig. 5
LED, but this is only to illustrate, and covers any number of LED particle, for example, shown in coverage diagram 1 each section all include
The case where several LED particles.
Preferably, LED drive circuit further includes third switching circuit, in parallel with the third section LED3 in the LED load,
Wherein the conducting voltage of the third section is less than the conducting voltage of the second segment；Wherein, the third switching circuit includes the
Three Integrated circuit IC 3, the third Integrated circuit IC 3 include the voltage detection terminal being connected with the cathode of the third section, are used in combination
It is opened when the voltage in the voltage detection terminal is lower than third threshold value by the third section short circuit, in the voltage detection terminal
Voltage disconnects when being higher than the third threshold value and opens the third section.The terminal of second Integrated circuit IC 3 connect and its with
The terminal connection and its connection relationship with corresponding LED that the connection relationship of LED3 can refer to third IC from top to bottom in Fig. 1,
Operation principles be also it is similar, details are not described herein.
Unlike the prior art in Fig. 1, first switch circuit here includes:
Voltage detecting circuit R1, R2 are connected to the power ground of the input terminal and input terminal, for detecting the input terminal
Voltage；
Comparison circuit Z1, voltage and first threshold for the input terminal；
Control circuit includes the switch Q1 and switching group Q5, Q3, Q2 in parallel with first segment LED1, for when described defeated
Switch Q1 is opened when entering the voltage at end less than the first threshold by the first segment LED1 short circuit, when the electricity of the input terminal
Pass Q1 is disconnected when pressure is greater than the first threshold to open the first segment LED1.
For more specifically, voltage detecting circuit R1, R2 constitute bleeder circuit, and one end is connected to the anode of rectifier bridge,
The other end is connected to the cathode (i.e. power ground) of rectifier bridge.So input terminal voltage detected is not to float, convenient for control
System.
Comparison circuit Z1 is realized by Zener diode, when the output of bleeder circuit is higher than the breakdown voltage of Zener diode
After (plus the base-collector junction conducting voltage of triode Q5), Zener diode Z1 and triode Q5 conducting, so that triode
Q3, Q2 and Q1 are turned off, so that first segment LED1 is driven by supply voltage.The breakdown voltage of Zener diode (adds
The base-collector junction conducting voltage of triode Q5) it should select are as follows: the input voltage that Z1 and Q5 is connected is higher than LED2's and LED1
The sum of conducting voltage, and it is substantially equal to the conducting voltage of (or being slightly above) LED1.Make when input voltage reaches the setting value
When one section of LED1 conducting, the 2nd IC and the 3rd IC automatically return on state and by second segment LED2 and the LED3 short circuit of third section.
Continue to increase with input voltage later, the 3rd IC and the 2nd IC can alternately and be simultaneously switched off again, this and the third in Fig. 1
The operation of IC and the 2nd IC be it is similar, details are not described herein.
In addition, Zener diode Z1 can also compensate the heat of the base-collector junction conducting voltage of triode Q5, Q3 etc. partially
It moves.Triode Q2 can amplify the base current of dual-polar triode Q1 when needing first segment LED1 short circuit.By increasing electricity
The resistance value for hindering R3 and R4, can reduce the power consumption of the circuit.Alternatively, switch Q1 can also be realized by MOSFET.
Since the conducting voltage of LED is there are tolerance, the conducting voltage of second segment LED2 and third section LED3 may be with differences
Batch or in same batch it is different.In extreme circumstances, the breakdown voltage of Zener diode is (plus the base of triode Q5
Pole-collector conducting voltage) conducting voltage with corresponding input voltage likely to be less than second segment LED2 and third section LED3
The sum of, this is likely to result in first segment LED1 and opens in advance rather than open-minded in second segment and third section LED as expected
It just starts to work later.In order to compensate for the error of this conducting voltage, in one preferred embodiment, compensation is additionally provided
Circuit R6, R7, Q4, R5, be connected to the second segment LED2 (or described third section LED3) anode and the voltage detecting
Circuit, to detect conducting voltage (or the electric conduction of the third section LED3 of the second segment LED2 and third section LED3
Pressure), and the voltage of the detected input terminal is adjusted according to the conducting voltage detected in the opposite direction.For example,
If the conducting voltage of second segment LED2 and third section LED3 are higher, the output for the bleeder circuit that R6, R7 are constituted is higher, Q4's
Impedance is lower, and R5, Q4, R8 are in parallel with the resistance R2 in bleeder circuit with lower impedance, so that the output voltage of bleeder circuit
It is lower.Therefore it needs higher input voltage that could obtain in the output end of bleeder circuit to be enough to be connected Zener diode Z1's
Voltage is detected, i.e., so that first segment LED1 is just connected in higher input voltage, this higher input voltage is conformed exactly to
Second segment LED2 and the higher conducting voltage of third section LED3.It will be appreciated that the compensation circuit is not required in that.
Although claims have been directed to the specific combination of feature and have formulated in this application, but it is to be understood that this public affairs
The range opened further includes disclosed herein explicitly or implicitly or to any of any novel feature of its any summary or feature
Novel combination, no matter whether it is related to the same approach in current any claim claimed.
Claims (22)
1. a kind of LED drive circuit characterized by comprising
Input terminal, the supply voltage changed over time for receiving instantaneous amplitude；
Output end, for being connected to LED load；
The switching circuit for adjusting the quantity of be connected to LED load come dynamic according to the instantaneous amplitude of the supply voltage, makes
The conducting voltage for obtaining be connected to LED load is matched with the instantaneous amplitude of the supply voltage, and wherein the switching circuit includes
With the LED load, concatenated multiple sections switches in parallel one by one；
Power switch is connected to the output end and is used to connect with the LED load, comes from the supply voltage with control
, the electric current of output end output；
Control loop, for detecting the electric current for flowing through the power switch, and the impedance for controlling the power switch makes the inspection
It surveys electric current and meets reference current；
The control loop includes:
Linear circuit is connected to the input terminal, within the scope of the acceptable specified mean value of the supply voltage, according to it is each
The one-to-one linear relationship of mean value, by instantaneous amplitude of the supply voltage in whole cycle with the constant linear relationship
The reference current is converted to fairly linearly.
2. LED drive circuit according to claim 1, which is characterized in that the linear circuit includes first resistor and
Bleeder circuit made of the series connection of two resistance, the control loop include:
With the concatenated detection resistance of the power switch；
Triode is controlled, collector is connected to the control electrode of the power switch, and base stage is connected to the detection resistance, and collects
Electrode is connected to the tie point of the first resistor and second resistance.
3. LED drive circuit according to claim 2, which is characterized in that the control electrode of the power switch passes through
Driving element is connected to the input terminal.
4. LED drive circuit according to claim 2, which is characterized in that further include:
Compensation circuit is connected to the input terminal and the linear circuit, for detecting the mean value of the supply voltage, and according to
The variation of the mean value changes the linear relationship.
5. LED drive circuit according to claim 4, which is characterized in that the compensation circuit includes:
Average capacitance, for detecting the mean value of the supply voltage；
Threshold element, for detecting whether the mean value is more than certain threshold value；
Switch controls the intrinsic standoff ratio of the bleeder circuit when the mean value is more than the threshold value.
6. LED drive circuit according to claim 5, which is characterized in that the switch works according to the mean value
Linear condition and the output for controlling the bleeder circuit in the opposite direction.
7. LED drive circuit according to claim 5 or 6, which is characterized in that it is described switch include double pole triode with
It is connected to the 3rd resistor of the emitter of the triode.
8. LED drive circuit according to any one of claim 1 to 6, which is characterized in that the input terminal is for receiving
The supply voltage that alternating current is changed over time as the instantaneous amplitude, and the acceptable specified mean value range is 198V-
264V。
9. a kind of LED drive circuit characterized by comprising
Input terminal, the supply voltage changed over time for receiving instantaneous amplitude；
Output end, for being connected to LED load；
The switching circuit for adjusting the quantity of be connected to LED load come dynamic according to the instantaneous amplitude of the supply voltage, makes
The conducting voltage for obtaining be connected to LED load is matched with the instantaneous amplitude of the supply voltage, and wherein the switching circuit includes
Switch in parallel, the switching circuit include: one by one with the LED load, concatenated multiple sections
First switch circuit, it is in parallel with the first segment in the LED load；
Second switch circuit, it is in parallel with the second segment in the LED load, wherein the conducting voltage of the second segment is less than described
The conducting voltage of first segment；
Wherein, the second switch circuit includes the second integrated circuit, and second integrated circuit includes and the second segment
The connected voltage detection terminal of cathode, and for opening when the voltage of the voltage detection terminal is lower than second threshold by described second
Section short circuit, disconnects when the voltage of the voltage detection terminal is higher than the second threshold and opens the second segment；
The first switch circuit includes:
Voltage detecting circuit is connected to the power ground of the input terminal and input terminal, for detecting the voltage of the input terminal；
Comparison circuit, voltage and first threshold for the input terminal；
Control circuit, it is for being opened when the voltage of the input terminal is less than the first threshold that the first segment is short-circuit, when
It is disconnected when the voltage of the input terminal is greater than the first threshold and opens the first segment.
10. LED drive circuit according to claim 9, which is characterized in that second integrated circuit includes TPS92411
Or TPS92411P chip, the conducting voltage of the second segment is less than 100 volts, and the conducting voltage of the first segment is greater than 100
Volt,
The anode of the first segment is connected to the anode of the input terminal, and the cathode of the first segment is connected to the second segment
Anode, and
The cathode of the second segment is couple to the power ground of the input terminal.
11. LED drive circuit according to claim 9 or 10, which is characterized in that the voltage detecting circuit includes partial pressure
Circuit, the comparison circuit include Zener diode, and the control circuit includes:
The first switch in parallel with the first segment；
The switching group being connected with the control electrode of the first switch, the switching group is connected to the input terminal and the comparison is electric
The first switch is connected for being biased by the voltage of the input terminal for road, and triggered by the comparison circuit and
The first switch is disconnected.
12. LED drive circuit according to claim 9 or 10, which is characterized in that shown switching circuit further include:
Third switching circuit, it is in parallel with the third section in the LED load, wherein the conducting voltage of the third section is less than described
The conducting voltage of second segment；
Wherein, the third switching circuit includes third integrated circuit, and the third integrated circuit includes and the third section
The connected voltage detection terminal of cathode, and for opening when the voltage of the voltage detection terminal is lower than third threshold value by the third
Section short circuit, disconnects when the voltage of the voltage detection terminal is higher than the third threshold value and opens the third section, and described second
Integrated circuit includes TPS92411 or TPS92411P chip, and the conducting voltage of the third section is less than 100 volts；
The cathode of the second segment is couple to the anode of the third section, and the cathode of the third section is connected to the input terminal
Power ground.
13. LED drive circuit according to claim 12, which is characterized in that the first switch circuit includes discrete element
Part, and further include:
Compensation circuit is connected to the anode and the voltage detecting circuit of the second segment or the third section, described in detection
The conducting voltage of the conducting voltage or the third section of second segment and the third section, and according to the conducting voltage detected come
The voltage of the detected input terminal is adjusted in the opposite direction.
14. LED drive circuit according to claim 9 or 10, which is characterized in that the input terminal is for receiving alternating current work
The supply voltage changed over time for the instantaneous amplitude, further includes:
Power switch is connected to the output end and is used to connect with the LED load, comes from the supply voltage with control
, the electric current of output end output；
Control loop, for detecting the electric current for flowing through the power switch, and the impedance for controlling the power switch makes the inspection
It surveys electric current and meets reference current；
The control loop includes:
Linear circuit is connected to the input terminal, within the scope of the acceptable specified mean value of the supply voltage, according to it is each
The one-to-one linear relationship of mean value, by instantaneous amplitude of the supply voltage in whole cycle with the constant linear relationship
The reference current is converted to fairly linearly,
Wherein the cathode of the second segment is connected to the power ground of the input terminal by the power switch.
15. LED drive circuit according to claim 14, which is characterized in that the linear circuit include first resistor and
The bleeder circuit that second resistance is connected in series, the control loop include:
With the concatenated detection resistance of the power switch；
Triode is controlled, collector is connected to the control electrode of the power switch, and base stage is connected to the detection resistance, and collects
Electrode is connected to the tie point of the first resistor and second resistance.
16. LED drive circuit according to claim 15, which is characterized in that the control electrode of the power switch is logical
Element of overdriving is connected to the input terminal.
17. LED drive circuit according to claim 15, which is characterized in that further include:
Compensation circuit is connected to the input terminal and the linear circuit, for detecting the mean value of the supply voltage, and according to
The variation of the mean value changes the linear relationship.
18. LED drive circuit according to claim 17, which is characterized in that the compensation circuit includes:
Average capacitance, for detecting the mean value of the supply voltage；
Threshold element, for detecting whether the mean value is more than certain threshold value；
Switch controls the intrinsic standoff ratio of the bleeder circuit when the mean value is more than the threshold value.
19. LED drive circuit according to claim 18, which is characterized in that the switch works according to the mean value
The output of the bleeder circuit is controlled in linear condition and in the opposite direction.
20. LED drive circuit described in 8 or 19 according to claim 1, which is characterized in that the switch includes ambipolar three pole
Manage and be connected to the 3rd resistor of the emitter of the triode.
21. LED drive circuit according to claim 14, which is characterized in that the input terminal is for receiving alternating current conduct
The supply voltage that the instantaneous amplitude changes over time, and the acceptable specified mean value range is 198V-264V.
22. a kind of lamps and lanterns, which is characterized in that including according to claim 1 to LED drive circuit described in any one of 21, and
The LED driven by the LED drive circuit.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201721280625.3U CN208434144U (en) | 2017-09-30 | 2017-09-30 | LED drive circuit and lamps and lanterns including the LED drive circuit |
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|---|---|---|---|
| CN201721280625.3U CN208434144U (en) | 2017-09-30 | 2017-09-30 | LED drive circuit and lamps and lanterns including the LED drive circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2020155413A1 (en) * | 2019-01-28 | 2020-08-06 | 苏州菲达旭微电子有限公司 | Linear high power factor driving circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2020155413A1 (en) * | 2019-01-28 | 2020-08-06 | 苏州菲达旭微电子有限公司 | Linear high power factor driving circuit |
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