CN104684141A - Light source driving circuit and controller - Google Patents

Light source driving circuit and controller Download PDF

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Publication number
CN104684141A
CN104684141A CN201310624881.XA CN201310624881A CN104684141A CN 104684141 A CN104684141 A CN 104684141A CN 201310624881 A CN201310624881 A CN 201310624881A CN 104684141 A CN104684141 A CN 104684141A
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China
Prior art keywords
current
signal
voltage
controller
electric current
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CN201310624881.XA
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Chinese (zh)
Inventor
郭清泉
王威
金艳艳
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O2Micro China Co Ltd
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O2Micro China Co Ltd
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Priority to CN201310624881.XA priority Critical patent/CN104684141A/en
Priority to GB201419030A priority patent/GB201419030D0/en
Publication of CN104684141A publication Critical patent/CN104684141A/en
Pending legal-status Critical Current

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Abstract

The invention discloses a light source driving circuit and a controller. The light source driving circuit comprises a buck-boost converter, a line voltage compensation circuit, a current monitor and a controller, wherein the buck-boost converter receives an input voltage and an input current from a power supply and provides electric energy for a load; the buck-boost converter includes a switch controlled by driving signals; the line voltage compensation circuit is used for generating voltage monitoring signals for indicating a magnitude of the input voltage; the current monitor is used for generating current monitoring signals for indicating the magnitude of the current flowing through the load; and the controller is used for receiving combined monitoring signals which are formed by overlapping the voltage monitoring signals and the current monitoring signals together; the combined monitoring signals indicate the magnitude of the input voltage as well as the magnitude of the current flowing through the load; and the controller generates driving signals according to the combined monitoring signals to control the switch, so as to reduce the influence of the changes of the input voltage to an input power and an output power of the buck-boost converter.

Description

Light source driving circuit and controller
Technical field
The present invention relates to a kind of drive circuit, particularly relate to a kind of light source driving circuit and the controller that drive LED source.
Background technology
Figure 1 shows that a kind of block diagram of traditional light source driving circuit 100.This drive circuit 100 for driving light source as light-emitting diode chain 108.Power supply 102 provides input voltage VIN to be that drive circuit 100 is powered.Drive circuit 100 comprises buck converter, this buck converter under the control of controller 104 for light-emitting diode chain 108 conversion is provided after voltage VOUT.This buck converter comprises diode 114, inductance 112, electric capacity 116 and switch 106.Resistance 110 is connected with switch 106.When switch 106 is connected, resistance 110 is coupled with inductance 112 and light-emitting diode chain 108, produces the feedback signal that instruction flows through the electric current of inductance 112.When switch 106 disconnects, resistance 110 disconnects with inductance 112 and light-emitting diode chain 108, does not thus have electric current to flow through resistance 110.
Switch 106 is controlled by controller 104.When switch 106 is connected, electric current flows through light-emitting diode chain 108, inductance 112, switch 106, resistance 110 to ground.Under the effect of inductance 112, electric current increases gradually.When electric current increases to default lowest high-current value, controller 104 cut-off switch 106.When switch 106 disconnects, electric current flows through light-emitting diode chain 108, inductance 112 and diode 114.Controller 104 turn on-switch 106 again over time.Therefore, controller 104 is according to described default lowest high-current value controlled hypotension converter.But, the average electrical flowing through inductance 112 and light-emitting diode chain 108 fail to be convened for lack of a quorum be subject to inductance 112 inductance value, input voltage VIN and light-emitting diode chain 108 two ends the impact of voltage VOUT, be therefore difficult to accurately control the average current flowing through inductance 112 (also namely flowing through the average current of light-emitting diode chain 108).
Summary of the invention
The technical problem to be solved in the present invention is to provide a kind of light source driving circuit and controller, to provide constant power output, and makes this light source driving circuit have higher power factor.
For solving the problems of the technologies described above, the invention provides a kind of light source driving circuit, this light source driving circuit comprises and falls booster converter, receives input voltage and input current and provides electric energy for load, fall booster converter and comprise the switch controlled by drive singal from power supply, line voltage compensation circuit, is coupled in power supply, for generation of the voltage monitoring signal of indicative input voltage swing, current monitor, is coupled in and falls between switch in booster converter and ground, flow through the current monitor signal of the size of current of load for generation of instruction, and controller, be coupled in and fall booster converter and line voltage compensation circuit, controller receives and superposes by voltage monitoring signal the combination monitor signal formed together with current monitor signal, combination monitor signal indicative input voltage swing and the size of current flowing through load, controller produces drive singal with control switch according to combination monitor signal, wherein, by line voltage compensation circuit make the magnitude of voltage of current monitor signal and flow through load current value all with input voltage inversely, when input voltage increases, the magnitude of voltage of current monitor signal correspondingly reduces and the current value flowing through load correspondingly reduces, when input voltage reduces, the magnitude of voltage of current monitor signal correspondingly increases and the current value flowing through load correspondingly increases.
Present invention also offers a kind of controller, for controlling, booster converter falls, fall booster converter and receive input voltage and input current from power supply, and provide electric energy for load, it is characterized in that, controller comprises: the first monitoring port, receives indicative input voltage swing and flows through the combination monitor signal of size of current of load, second monitoring port, receive the monitor signal that the situation of the energy-storage units in booster converter falls in instruction, wherein the electric current of energy-storage units is by switch control rule, if the electric current that monitor signal instruction flows through energy-storage units is reduced to pre-set current value, controller turn on-switch, and driving port, according to combination monitor signal and monitor signal provide drive singal to switch with control flow check through falling the transient current of booster converter, thus regulate the size of current flowing through load, the electric current wherein flowing through load be line voltage compensation circuit by being coupled in the first monitoring port and with input voltage inversely, when input voltage increases, the electric current flowing through load correspondingly reduces, when input voltage reduces, the electric current flowing through load correspondingly increases, thus reduce the impact of change for the input power and power output of falling booster converter of input voltage.
Light source driving circuit provided by the invention and controller, by utilize line voltage compensation circuit make the magnitude of voltage of current monitor signal and flow through load current value all with input voltage inversely, thus can reduce even eliminate input voltage change on the impact of the input power and power output of falling booster converter.
Accompanying drawing explanation
Below by way of to the description of some embodiments of the present invention in conjunction with its accompanying drawing, object of the present invention, specific structural features and advantage can be understood further.
Figure 1 shows that a kind of block diagram of conventional light source drive circuit;
Figure 2 shows that the block diagram of light source driving circuit according to an embodiment of the invention;
Figure 3 shows that the circuit diagram of light source driving circuit according to an embodiment of the invention;
Figure 4 shows that the structural representation of Fig. 3 middle controller;
Figure 5 shows that the oscillogram of Fig. 4 middle controller;
Figure 6 shows that the another kind of structural representation of Fig. 3 middle controller;
Figure 7 shows that the signal waveforms that Fig. 6 middle controller generates or receives;
Figure 8 shows that the circuit diagram of light source driving circuit in accordance with another embodiment of the present invention;
Fig. 9 A is depicted as the block diagram of light source driving circuit in accordance with another embodiment of the present invention;
Fig. 9 B is depicted as the signal waveforms that in Fig. 9 A, drive circuit generates or receives;
Figure 10 shows that the circuit diagram of the light source driving circuit according to another embodiment of the present invention;
Figure 11 shows that the structural representation of Fig. 9 A middle controller;
The signal waveforms that Figure 12 shows that light source driving circuit generation according to an embodiment of the invention or receive;
Figure 13 shows that the method flow diagram driving load according to an embodiment of the invention;
Figure 14 shows that the circuit diagram of the light source driving circuit according to another embodiment of the present invention;
Figure 15 shows that the structural representation of Figure 14 middle controller according to an embodiment of the invention;
Figure 16 shows that the circuit diagram according to the present invention's light source driving circuit of another embodiment again;
Figure 17 shows that the circuit diagram according to the present invention's light source driving circuit of another embodiment again;
The signal waveforms that Figure 18 shows that light source driving circuit generation in accordance with another embodiment of the present invention or receive.
Figure 19 shows that the circuit diagram of the light source driving circuit according to another embodiment of the present invention;
Figure 20 shows that the structural representation of Figure 19 middle controller;
Figure 21 is depicted as the circuit diagram of the light source driving circuit according to another embodiment of the present invention;
Figure 22 is depicted as the circuit diagram of the light source driving circuit according to another embodiment of the present invention;
Figure 23 is depicted as the waveform schematic diagram that in Figure 22, input power and power output change along with input voltage; And
Figure 24 to be depicted as in Figure 22 input power and power output along with the waveform schematic diagram of variation of ambient temperature.
Embodiment
Below will provide detailed description to embodiments of the invention.Although the present invention is undertaken setting forth and illustrating by these execution modes, it should be noted that the present invention is not merely confined to these execution modes.On the contrary, all substitutes, variant and the equivalent in invention spirit and invention scope that appended claim defines is contained in the present invention.
In addition, in order to better the present invention is described, in embodiment hereafter, give numerous details.It will be understood by those skilled in the art that do not have these details, the present invention can implement equally.In other example, known method, flow process, element and circuit are not described in detail, so that highlight purport of the present invention.
Figure 2 shows that the block diagram of light source driving circuit 200 according to an embodiment of the invention.Light source driving circuit 200 comprises rectifier 204.Rectifier 204 receives input voltage from power supply 202 and provides the voltage after adjustment for power converter 206.Voltage after power converter 206 receives adjustment also provides output power for load 288.Power converter 206 can be buck converter or booster converter.In one embodiment, power converter 206 comprises energy-storage units 214 and the current monitor 278(such as resistance for monitoring energy-storage units 214 situation).Current monitor 278 provides induced signal ISEN for controller 210.This induced signal ISEN instruction flows through the transient current of energy-storage units 214.Light source driving circuit 200 also comprises filter 212, for producing induced signal IAVG according to induced signal ISEN.Induced signal IAVG instruction flows through the average current of energy-storage units 214.Controller 210 receives induced signal ISEN and induced signal IAVG, and control flow check is through the average current of energy-storage units 214, makes this average current equal with target current value.
Figure 3 shows that the circuit diagram of light source driving circuit 300 according to an embodiment of the invention.Number identical parts in Fig. 3 with Fig. 2 and there is similar function.In the example in figure 3, light source driving circuit 300 comprises rectifier 204, power converter 206, filter 212 and controller 210.Rectifier 204 can be the bridge rectifier comprising diode D1-D4.Rectifier 204 adjusts the voltage from power supply 202.Power converter 206 receive rectifier 204 export adjustment after voltage and produce output power be load (as light-emitting diode chain 208) power supply.
In the example in figure 3, power converter 206 is buck converters.This buck converter comprises electric capacity 308, switch 316, diode 314, current monitor 278(such as resistance 218), the inductance 302 intercoupled and inductance 304 and electric capacity 324.Diode 314 is between switch 316 and the ground of light source driving circuit 300.Electric capacity 324 is in parallel with light-emitting diode chain 208.In one embodiment, inductance 302 and inductance 304 electromagnetic coupled each other.Inductance 302 and inductance 304 are all connected to a common node 333.In the example in figure 3, common node 333 is between resistance 218 and inductance 302.But the present invention is not limited to this structure, common node 333 also can between switch 316 and resistance 218.Common node 333 for controller 210 provide with reference to ground.In one embodiment, the reference ground of controller 210 is different with the ground of light source driving circuit 300.By switching on and off switch 316, the electric current flowing through inductance 302 can be adjusted, thus regulates the electric power of light-emitting diode chain 208.Inductance 304 monitors the situation of inductance 302, and such as, whether monitoring stream is reduced to default current value through the electric current of inductance 302.
One end of resistance 218 is connected with the node between switch 316 and diode 314 negative electrode, and the other end is connected with inductance 302.Resistance 218 provides induced signal ISEN, and when switch 316 switches on and off, this induced signal ISEN all can indicate the transient current flowing through inductance 302.In other words, when connecting regardless of switch 316 or disconnect, resistance 218 equal energy monitoring stream is through the transient current of inductance 302.Filter 212 is coupled with resistance 218 and provides induced signal IAVG, and this induced signal IAVG instruction flows through the average current of inductance 302.In one embodiment, filter 212 comprises resistance 320 and electric capacity 322.
Controller 210 receives induced signal ISEN and induced signal IAVG, and makes the average current flowing through inductance 302 equal target current value by being switched on or switched off switch 316.Electric capacity 324 filtering flows through the ripple of the electric current of light-emitting diode chain 208, thus the electric current making to flow through light-emitting diode chain 208 relatively steadily and equal to flow through the average current of inductance 302.Therefore make the electric current flowing through light-emitting diode chain 208 equal with target current value.Herein " equal with target current value " be when do not consider circuit element undesirable situation and ignore be sent to the electric power of controller 210 from inductance 304.
In the example of Fig. 3, the port of controller 210 comprises ZCD, GND, DRV, VDD, CS, COMP and FB.Port ZCD is coupled with inductance 304, for receiving the monitor signal AUX of instruction inductance 302 situation (whether the electric current such as, flowing through inductance 302 is reduced to default current value " 0 ").Whether monitor signal AUX also indication light diode chain 208 can be in open-circuit condition.Port DRV is coupled with switch 316 and produces drive singal (as pulse width modulating signal PWM1) and is switched on or switched off switch 316.Port VDD is coupled with inductance 304 and receives the electric power of self-inductance 304.Port CS is coupled with resistance 218 and receives the induced signal ISEN indicating the transient current flowing through inductance 302.Port COMP is coupled by the reference of electric capacity 318 and controller 210.Port FB to be coupled with resistance 218 by filter 212 and to receive the induced signal IAVG indicating the average current flowing through inductance 302.In the example in figure 3, reference of port GND(also i.e. controller 210) be connected to common node 333 between resistance 218, inductance 302, inductance 304.
Switch 316 can be N-type mos field effect transistor (N-type MOSFET).The conducting state of switch 316 is determined by the voltage difference between the grid voltage of switch 316 and the voltage (i.e. the voltage of common node 333) of port GND.Therefore, the pulse width modulating signal PWM1 that port DRV exports determines the state of switch 316.When switch 316 is connected, the reference ground of controller 210, higher than the ground of light source driving circuit 300, makes circuit of the present invention go for having the power supply of high voltage.
When switch 316 is connected, electric current flows through switch 316, resistance 218, inductance 302, light-emitting diode chain 208 to the ground of light source driving circuit 300.When switch 316 disconnects, electric current flows through resistance 218, inductance 302, light-emitting diode chain 208 and diode 314.Inductance 304 is coupled with inductance 302 and can monitors the situation of inductance 302, and such as, whether monitoring stream is reduced to pre-set current value through the electric current of inductance 302.Controller 210 according to the electric current of signal AUX, ISEN and IAVG monitoring stream through inductance 302, and by pulse width modulating signal PWM1 control switch 316, makes the average current flowing through inductance 302 equal target current value.So after electric capacity 324 filtering, the electric current flowing through light-emitting diode chain 208 also equals target current value.
In one embodiment, according to monitor signal AUX, controller 210 judges whether light-emitting diode chain 208 is in open-circuit condition.If light-emitting diode chain 208 is opened a way, then the voltage on electric capacity 324 increases.When switch 316 is in off-state, the voltage at inductance 302 two ends increases, and the voltage of monitor signal AUX also increases thereupon.Consequently, increased by the electric current of port ZCD ramp metering device 210.Therefore, more than a current threshold, whether controller 210 judges whether light-emitting diode chain 208 is in open-circuit condition by the electric current of monitor signal AUX and ramp metering device 210 when switch 316 is in off-state.
According to the voltage of port VDD, controller 210 judges whether light-emitting diode chain 208 is in short-circuit condition.If light-emitting diode chain 208 short circuit, when switch 316 is in off-state, because inductance 302 two ends are all coupled with the ground of light source driving circuit 300, so the voltage at inductance 302 two ends reduces.The voltage at inductance 304 two ends and the voltage of port VDD reduce thereupon.If the voltage of port VDD is less than a voltage threshold when switch 316 is in off-state, controller 210 judges that light-emitting diode chain 208 is in short-circuit condition.
Figure 4 shows that the structural representation of Fig. 3 middle controller 210.Figure 5 shows that the oscillogram of Fig. 4 middle controller 210.Composition graphs 3 and Fig. 5 are described by Fig. 4.
In the example in fig. 4, controller 210 comprises error amplifier 402, comparator 404 and pulse width modulating signal generator 408.Error amplifier 402 produces error signal VEA according to the voltage difference between reference signal SET and induced signal IAVG.Reference signal SET indicating target current value.Induced signal IAVG is received by port FB, and instruction flows through the average current of inductance 302.The average current flowing through inductance 302 is made to equal target current value by the effect of error signal VEA.Comparator 404 is coupled with error amplifier 402, is compared by error signal VEA and induced signal ISEN.Induced signal ISEN is received by port CS, and instruction flows through the transient current of inductance 302.Monitor signal AUX is received by port ZCD, and whether the electric current that instruction flows through inductance 302 is reduced to pre-set current value (being such as reduced to 0).Pulse width modulating signal generator 408 is coupled with comparator 404 and port ZCD, according to output and the monitor signal AUX generation pulse width modulating signal PWM1 of comparator 404.Pulse width modulating signal PWM1 is by the conducting state of port DRV control switch 316.
Pulse width modulating signal generator 408 generation has the pulse width modulating signal PWM1 of the first state (as logical one) with turn on-switch 316.When switch 316 is connected, electric current flows through switch 316, resistance 218, inductance 302, light-emitting diode chain 208 to the ground of light source driving circuit 300.The electric current flowing through inductance 302 increases gradually, and the voltage of signal ISEN is increased gradually.In one embodiment, when switch 316 is connected, the voltage of monitor signal AUX is negative value.Inner at controller 210, error signal VEA and induced signal ISEN compares by comparator 404.When the voltage of induced signal ISEN exceedes the voltage of error signal VEA, the output of comparator 404 is logical zero, otherwise the output of comparator 404 is logical one.In other words, the output of comparator 404 is a series of pulse.Under the effect of the trailing edge of comparator 404 output, pulse width modulating signal generator 408 generation has the pulse width modulating signal PWM1 of the second state (as logical zero) with cut-off switch 316.When switch 316 disconnects, the voltage of monitor signal AUX become on the occasion of.When switch 316 disconnects, electric current flows through resistance 218, inductance 302, light-emitting diode chain 208 and diode 314.The electric current flowing through inductance 302 reduces gradually, and therefore the voltage of induced signal ISEN reduces gradually.When the electric current flowing through inductance 302 is reduced to pre-set current value (as being reduced to 0), the voltage of monitor signal AUX can produce a trailing edge.Under the effect of monitor signal AUX trailing edge, the generation of pulse width modulating signal generator 408 has the pulse width modulating signal PWM1 of the first state (as logical one) with turn on-switch 316.
In one embodiment, the duty ratio of pulse width modulating signal PWM1 is determined by error signal VEA.If the voltage of induced signal IAVG is less than the voltage of reference signal SET, then error amplifier 402 increases the voltage of error signal VEA to increase the duty ratio of pulse width modulating signal PWM1, thus the average current flowing through inductance 302 is increased, until the voltage of induced signal IAVG increases to the voltage of reference signal SET.If the voltage of induced signal IAVG is greater than the voltage of reference signal SET, then error amplifier 402 reduces the voltage of error signal VEA to reduce the duty ratio of pulse width modulating signal PWM1, thus the average current flowing through inductance 302 is reduced, until the voltage of induced signal IAVG is reduced to the voltage of reference signal SET.Like this, the average current flowing through inductance 302 can be adjusted to equal with target current value.
Controller 210 also comprises the startup and low pressure lock-in circuit 401 that are coupled in its port VDD, for the one or more parts according to different power levels optionally start-up connector 210 inside.In one embodiment, if the voltage on port VDD is higher than the first predeterminated voltage, then startup and low pressure lock-in circuit 401 are by parts all in start-up connector 210.If the voltage on port VDD is lower than the second predeterminated voltage, startup and low pressure lock-in circuit 401 are by parts all in closing controller 210.In one embodiment, the first predeterminated voltage is higher than the second predeterminated voltage.Port VDD is used for providing electric energy to controller 210.Port GND is coupled in the reference ground of controller 210.
Figure 6 shows that the another kind of structural representation of Fig. 3 middle controller 210.Figure 7 shows that the oscillogram of Fig. 6 middle controller 210.Composition graphs 3 and Fig. 7 are described by Fig. 6.
In the example of fig. 6, controller 210 comprises error amplifier 602, comparator 604, going sawtooth signal generator 606, reset signal generator 608 and pulse width modulating signal generator 610.Error amplifier 602 produces error signal VEA according to the voltage difference between reference signal SET and induced signal IAVG.Reference signal SET indicating target current value.Induced signal IAVG is received by port FB, and instruction flows through the average current of inductance 302.The average current flowing through inductance 302 is made to equal target current value by the effect of error signal VEA.Going sawtooth signal generator 606 produces sawtooth signal SAW.Comparator 604 is coupled with error amplifier 602 and going sawtooth signal generator 606, and is compared by error signal VEA and sawtooth signal SAW.Reset signal generator 608 produces reset signal RESET.Reset signal RESET acts on going sawtooth signal generator 606 and pulse width modulating signal generator 610.Switch 316 can be made under the effect of reset signal RESET to connect.Pulse width modulating signal generator 610 is coupled with comparator 604 and reset signal generator 608, and produces pulse width modulating signal PWM1 according to the output of comparator 604 and reset signal RESET.Pulse width modulating signal PWM1 is by the conducting state of port DRV control switch 316.
In one embodiment, reset signal RESET is the pulse signal with fixed frequency.In another embodiment, reset signal RESET is the time making switch 316 be in off-state is the pulse signal of constant.Such as, in the figure 7, reset signal RESET makes pulse width modulating signal PWM1 be time of logical zero is constant.
Under the effect of the pulse of reset signal RESET, pulse width modulating signal generator 610 generation has the pulse width modulating signal PWM1 of the first state (as logical one) with turn on-switch 316.When switch 316 is connected, electric current flows through switch 316, resistance 218, inductance 302, light-emitting diode chain 208 to the ground of light source driving circuit 300.Under the effect of the pulse of reset signal RESET, the voltage of the sawtooth signal SAW that going sawtooth signal generator 606 produces increases from initial value INI.When the voltage of sawtooth signal SAW increases to the voltage of error signal VEA, pulse width modulating signal generator 610 generation has the pulse width modulating signal PWM1 of the second state (as logical zero) with cut-off switch 316, and the voltage of sawtooth signal SAW is reset to initial value INI.Until when the next pulse of reset signal RESET arrives, the voltage of sawtooth signal SAW just from initial value INI again increase.
In one embodiment, the duty ratio of pulse width modulating signal PWM1 is determined by error signal VEA.If the voltage of induced signal IAVG is less than the voltage of reference signal SET, then error amplifier 602 increases the voltage of error signal VEA to increase the duty ratio of pulse width modulating signal PWM1, thus the average current flowing through inductance 302 is increased, until the voltage of induced signal IAVG increases to the voltage of reference signal SET.If the voltage of induced signal IAVG is greater than the voltage of reference signal SET, then error amplifier 602 reduces the voltage of error signal VEA to reduce the duty ratio of pulse width modulating signal PWM1, thus the average current flowing through inductance 302 is reduced, until the voltage of induced signal IAVG is reduced to the voltage of reference signal SET.Like this, the average current flowing through inductance 302 can be adjusted to equal with target current value.
Figure 8 shows that the circuit diagram of light source driving circuit light source driving circuit 800 in accordance with another embodiment of the present invention.Number identical parts in Fig. 8 with Fig. 2, Fig. 3 and there is similar function.
The port VDD of controller 210 receives the voltage after the adjustment that rectifier 204 exports by switch 804.The voltage substantially constant of port VDD is kept with reference to the Zener diode 802 between ground at switch 804 and controller 210.In the example of Fig. 8, the port ZCD of controller 210 is coupled with inductance 302, receives the monitor signal AUX of instruction inductance 302 situation.Monitor signal AUX can indicate the electric current flowing through inductance 302 whether to be reduced to pre-set current value (such as whether being reduced to 0).Common node 333 for controller 210 provide with reference to ground.
In sum, the invention provides a kind of power converter that controls with the circuit to load supplying.This circuit comprises for the current monitor of monitoring stream through the electric current of energy-storage units (such as inductance), and controller.This controller for controlling the switch with described inductance coupling high, thus makes the average current flowing through described light source equal target current value.No matter this switch connection or disconnection, this current monitor equal energy monitoring stream is through the electric current of described inductance.In one embodiment, power converter is that load (such as light-emitting diode chain) provides direct current.In another embodiment, power converter provides the charging current of direct current for battery.Compared with the traditional circuit in Fig. 1, the electric current that circuit of the present invention is supplied to load or battery can obtain controlling more accurately.And circuit of the present invention goes for the voltage source with high voltage.
Fig. 9 A is depicted as the block diagram of light source driving circuit 900 in accordance with another embodiment of the present invention.Number identical parts in Fig. 9 A with Fig. 2, Fig. 3 and there is similar function.In one embodiment, light source driving circuit 900 comprise be coupled with power supply 202 filter 920, rectifier 204, power converter 906, load 288, going sawtooth signal generator 902 and controller 910.Power supply 202 produces AC-input voltage V aC(such as, V aCthere is sine wave signal) and AC input current I aC.AC input current I aCflow into filter 920.Electric current I aC' flow out from filter 920, and flow into rectifier 204.Rectifier 204 receives AC-input voltage V by filter 920 aC, and commutating voltage V is provided on power line 912 iNwith rectified current I iN.Power line 912 is coupled between rectifier 204 and power converter 906.Power converter 906 is by commutating voltage V iNconvert output voltage V to oUT, for load 288 provides electric energy.Controller 910 is coupled with power converter 906, for controlling power converter 906, to regulate the electric current I flowing through load 288 oUT, and correct the power factor of drive circuit 900.
Controller 910 produces drive singal 962.In one embodiment, power converter 906 comprises switch 316.Drive singal 962 control switch 316, thus regulate the electric current I flowing through load 288 oUT.Power converter 906 also generates the electric current I that instruction flows through load 288 oUTinduced signal IAVG.
In one embodiment, the going sawtooth signal generator 902 be coupled with controller 910, generates sawtooth signal 960 according to drive singal 962.Such as, drive singal 962 can be pulse width modulating signal.In one embodiment, when drive singal 962 is logic high, sawtooth signal 960 increases; When drive singal 962 is logic low, sawtooth signal 960 is reduced to preset voltage value (being such as reduced to 0V).
Advantageously, controller 910 produces drive singal 962 according to sawtooth signal 960 and induced signal IAVG.Drive singal 962 control switch 316, makes the electric current I flowing through load 288 oUTremain on target current value, to improve the accuracy of Current Control.In addition, drive singal 962 control switch 316, regulates rectified current I iNaverage current I iN_AVGwith commutating voltage V iNessence homophase, to correct the power factor of drive circuit 900.In the application, essence homophase refers to same-phase on two waved theory, but in actual applications, due to the existence of electric capacity in circuit, causes two waveforms to there is trickle difference.The operation principle of drive circuit 900 will further describe in figures 9 b and 9.
Fig. 9 B is depicted as the oscillogram of the signal in the drive circuit 900 in Fig. 9 A according to one embodiment of present invention, and composition graphs 9A describes by Fig. 9 B.Fig. 9 B describes AC-input voltage V aC, commutating voltage V iN, rectified current I iN, rectified current average current I iN_AVG, electric current I aC' and AC input current I aCwaveform.
For convenience of description, AC-input voltage V aCfor (being not limited to) sinusoidal waveform.Rectifier 204 rectification AC-input voltage V aC.In the embodiment of Fig. 9 B, commutating voltage V iNthere is the sinusoidal waveform after rectification, that is, AC-input voltage V aCforward waveform retain, its negative sense waveform converts corresponding forward waveform to.
In one embodiment, the drive singal 962 that controller 910 produces controls rectified current I iN.Rectified current I iNincrease from a preset value (as zero ampere).As rectified current I iNreach and commutating voltage V iNafter a proportional value, rectified current I iNdrop to preset value.As shown in Figure 9 B, rectified current I iNaverage current I iN_AVGwaveform and commutating voltage V iNwaveform essence homophase.
Rectified current I iNflow out from rectifier 204 and flow into power converter 906.Rectified current I iNit is the electric current I flowing into rectifier 204 aC' electric current after rectification.As shown in Figure 9 B, as AC-input voltage V aCfor on the occasion of time, electric current I aC' forward waveform and rectified current I iNforward waveform similar; As input current voltage V aCduring for negative value, electric current I aC' negative sense waveform and rectified current I iNwaveform corresponding.
In one embodiment, by adopting the filter 920 be coupled between power supply 202 and rectifier 204, AC input current I aCwith electric current I aC' mean value equal or proportional.Therefore, as shown in Figure 9 B, AC input current I aCwaveform and AC-input voltage V aCwaveform essence homophase.In theory, AC input current I aCwith AC-input voltage V aChomophase.But, in actual applications, owing to there is electric capacity in filter 920 and power converter 906, AC input current I aCwith AC-input voltage V aCbetween may there is trickle difference.In addition, AC input current I aCwith AC-input voltage V aCwaveform is also roughly similar.Therefore, the power factor of drive circuit 900 obtains correction, thus improves the power supply quality of drive circuit 900.
Figure 10 shows that the circuit diagram of light source driving circuit 1000 according to still a further embodiment.Number identical parts with Fig. 2, Fig. 3 and Fig. 9 A in Figure 10 and there is similar function.Composition graphs 4, Fig. 5 and Fig. 9 A are described by Figure 10.
In the example of Figure 10, drive circuit 1000 comprise be coupled in power supply 202 filter 920, rectifier 204, power converter 906, load 288, going sawtooth signal generator 902 and controller 910.In one embodiment, load 288 comprises LED source (as light-emitting diode chain 208).The present invention is not limited thereto, and load 288 can comprise the light source of other types or the load (as battery pack) of other types.Filter 920 can be the inductive-capacitive filter that (being not limited to) comprises a pair inductance and a pair electric capacity.In one embodiment, controller 910 comprises multiple port, such as ZCD port, GND port, DRV port, vdd terminal mouth, FB port, COMP port and CS port.
In one embodiment, power converter 906 comprises the input capacitance 1008 being coupled in power line 912.Input capacitance 1008 reduces commutating voltage V iNripple, with smooth commutation voltage V iNwaveform.In one embodiment, electric capacity 1008 has relatively little capacitance (such as, being less than 0.5 microfarad), to help to eliminate or reduce commutating voltage V iNthe distortion of waveform.In addition, in one embodiment, because electric capacity 1008 is less, the electric current flowing through electric capacity 1008 can be ignored.Therefore, when switch 316 is connected, the electric current I of switch 316 is flowed through 214with the rectified current I flowed out from rectifier 204 iNroughly equal.
The class of operation of power converter 906 and the power converter 206 in Fig. 3 seemingly.In one embodiment, energy-storage units 214 comprises inductance 302 and inductance 304, and inductance 302 electromagnetic coupled is in inductance 304.Inductance 302 is coupled with switch 316 and light-emitting diode chain 208.Therefore, according to the conducting state of switch 316, electric current I 214flow through inductance 302.More specifically, in one embodiment, controller 910 produces drive singal 962(as pulse width modulating signal on DRV port), be switched on or switched off with control switch 316.When switch 316 closes, electric current I 214flow out from power line 912, flow through switch 316 and inductance 302, and constantly increase.Electric current I 214can be drawn by formula (1):
△I 214=(V IN–V OUT)×T ON/L 302(1)，
Wherein, T oNrepresent the time of switch 316 conducting, △ I 214represent electric current I 214variable quantity, L 302represent the inductance value of inductance 302.In one embodiment, controller 910 controls drive singal 962, makes T oNit is a steady state value.So, if output voltage V oUTsubstantially constant, at T oNin the time interval, electric current I 214variable quantity △ I 214with commutating voltage V iNproportional.In one embodiment, electric current I is worked as 214when being reduced to preset value (as zero ampere), switch 316 closes.Therefore, electric current I 214peak value and commutating voltage V iNproportional.
When switch 316 disconnects, electric current I 214flow out from ground, and flow through diode 314 and inductance 302, flow to light-emitting diode chain 208.Accordingly, electric current I 214reduce according to formula (2):
△I 214=(–V OUT)×T OFF/L 302(2)。
Wherein, T oFFrepresent the turn-off time of switch 316.
In one embodiment, when switch 316 conducting, electric current I iNwith electric current I 214equal, when switching tube 316 disconnects, electric current I iNequal zero ampere.
The situation of inductance 304 inductive sensor 302, such as, whether the electric current flowing through inductance 302 drops to pre-set current value, such as zero ampere.Described in composition graphs 5, in one embodiment, when switch 316 closes, monitor signal AUX is low level, and when switch 316 disconnects, monitor signal AUX is high level.When the electric current I 214 flowing through inductance 302 is reduced to pre-set current value, the voltage of monitor signal AUX produces a trailing edge.The ZCD port of controller 910 is coupled in inductance 304, is used for receiving monitor signal AUX.
In one embodiment, power converter 906 comprises output filter 1024.Output filter 1024 can be the electric capacity (such as, being greater than 400 microfarads) with relatively large capacitance.So, flow through the electric current I of light-emitting diode chain 208 oUTrepresent electric current I 214mean value.
Current monitor 218 produces the induced signal ISEN that instruction flows through the electric current of inductance 302.In one embodiment, filter 212 is for comprising the resistance-capacitance filter of resistance 320 and electric capacity 322.The ripple in current sensing signal ISEN removed by filter 212, with the average current induced signal IAVG of generation current induced signal ISEN.So in the embodiment in figure 10, average current induced signal IAVG instruction flows through the electric current I of light-emitting diode chain 208 oUT.The port FB of controller 910 is for receiving average current induced signal IAVG.
Going sawtooth signal generator 902 is coupled in DRV port and CS port.Going sawtooth signal generator 902 produces sawtooth signal 960 according to the drive singal 962 of DRV port on CS port.Such as, going sawtooth signal generator 902 comprises and is coupled in resistance 1016 between DRV port and CS port and parallel with one another and diode 1018, also comprises and is coupled in resistance 1012 between CS port and ground and parallel with one another and electric capacity 1014.During work, sawtooth signal 960 changes according to drive singal 962.More specifically, in one embodiment, drive singal 962 is pulse width modulating signal.When drive singal 962 is logic high, electric current I 1 flows out from DRV port, through resistance 1016, flows into electric capacity 1014.Therefore, electric capacity 1014 is charged, the voltage V of sawtooth signal 960 960increase.When drive singal 962 is logic low, electric current I 2 flows out from electric capacity 1014, through diode 1018, and flows into DRV port.Therefore, electric capacity 1014 discharges, voltage V 960be reduced to zero volt.Going sawtooth signal generator 902 can also comprise other assemblies, is not limited to the embodiment shown in Figure 10.
In one embodiment, controller 910 is integrated in an integrated circuit (IC) chip.Resistance 1016 and 1012, diode 1018 and electric capacity 1014 is the peripheral circuit assembly of this integrated circuit (IC) chip.In another embodiment, going sawtooth signal generator 902 and controller 910 also can be integrated in an integrated circuit (IC) chip.In this embodiment, CS port can be omitted, thus reduce size and the cost of drive circuit 1000.Power converter 906 can also have other structures, is not limited to the embodiment shown in Figure 10.
Figure 11 shows that the structural representation of Fig. 9 A middle controller 910 according to an embodiment of the invention.Number identical parts with Fig. 4 and Fig. 9 A in Figure 11 and there is similar function.Composition graphs 4, Fig. 5, Fig. 9 A and Figure 10 are described by Figure 11.
In one embodiment, controller 910 has similar structure to the controller 210 in Fig. 4, and difference is, CS port accepts sawtooth signal 960 instead of current sensing signal ISEN.Controller 910 produces drive singal 962 according to sawtooth signal 960, average current induced signal IAVG and monitor signal AUX.Controller 910 comprises error amplifier 402, comparator 404 and pulse-width signal generator 408.Error amplifier 402, according to the difference between average current induced signal IAVG and the reference signal SET representing target current value, produces error signal VEA.Comparator 404 compares sawtooth signal 960 and error signal VEA, to produce comparison signal S.Pulse width modulating signal generator 408 is surveyed signal AUX according to comparison signal S and monitoring and is produced drive singal 962.
In one embodiment, when monitor signal AUX instruction flows through the electric current I of inductance 302 214when dropping to preset value (as zero ampere), drive singal 962 switches to the first level (as logic high), with Closing Switch 316.When sawtooth signal 960 reaches error signal VEA, drive singal 962 switches to second electrical level (as logic low), with cut-off switch 316.Advantageously, due to CS port accepts sawtooth signal 960 instead of current sensing signal ISEN, the electric current I of inductance 302 is flowed through 214peak value can not be limited to error signal VEA.Therefore, as described in formula (1), the electric current I of inductance 302 is flowed through 214according to commutating voltage V iNchange.Such as, electric current I 214peak value and commutating voltage V iNproportional instead of proportional with error signal VEA.
Controller 910 controls drive singal 962, to make electric current I oUTremain on the target current value represented by reference signal SET.Such as, if electric current I oUTbe greater than target current value (as due to commutating voltage V iNchange), error amplifier 402 reduces error signal VEA, to shorten the closed time T of switch 316 oN.So, electric current I 214average current reduce, to reduce electric current I oUT.Same, if electric current I oUTbe less than target current value, controller 910 extends the closed time T of switch 316 oN, to increase electric current I oUT.
The signal waveforms that Figure 12 shows that light source driving circuit (as drive circuit 900 or 1000) generation according to an embodiment of the invention or receive.Composition graphs 4, Fig. 9 A, Fig. 9 B and Figure 10 are described by Figure 12.Figure 12 describes commutating voltage V iN, rectified current I iN, rectified current I iNaverage current I iN_AVG, flow through the electric current I of light-emitting diode chain 208 oUT, instruction flows through the electric current I of inductance 302 214induced signal ISEN, error signal VEA, sawtooth signal 960 and drive singal 962.
As shown in figure 12, commutating voltage V iNit is the sine wave signal after rectification.In the t1 moment, drive singal 962 becomes logic high.Therefore, switch 316 closes, and instruction flows through the electric current I of inductance 302 214induced signal ISEN increase.Meanwhile, sawtooth signal 960 increases according to drive singal 962.
In the t2 moment, sawtooth signal 960 is increased to error signal VEA.Accordingly, controller 910 regulates drive singal 962 for logic low, and sawtooth signal 960 drops to zero volt.Drive singal 962 cut-off switch 316, therefore, induced signal ISEN declines.In other words, sawtooth signal 960 and error signal VEA determine the time T of drive singal 962 logic high oN.
In the t3 moment, electric current I 214be reduced to pre-set current value (as zero ampere), thus, controller 910 regulates drive singal 962 for logic high, with Closing Switch 316.
In one embodiment, at commutating voltage V iNone-period in, flow through the electric current I of light-emitting diode chain 208 oUTwith electric current I 214mean value equal or proportional.In conjunction with the description of Figure 11, controller 910 regulates electric current I oUTto the target current value represented by reference signal SET.In addition, as shown in figure 12, electric current I is represented 214induced signal ISEN during t1 to t4 with there is during t5 to t6 identical waveform.So, electric current I 214mean value during t1 to t4 is equal with the mean value during t5 to t6.Therefore, electric current I oUTremain on target current value.In one embodiment, T oNdetermined by sawtooth signal 960 and error signal VEA.Due within each cycle of drive singal 962, the time that sawtooth signal 960 rises to error signal VEA from zero volt is all equal, so T oNconstant.According to formula (1), at T oNin time, electric current I 214variable quantity △ I 214with commutating voltage V iNproportional.So, as shown in figure 12, the peak value of induced signal ISEN and commutating voltage V iNproportional.
In one embodiment, when switch 316 closes, electric current I iNwaveform and electric current I 214waveform similar, when switch 316 disconnects, electric current I iNequal zero ampere.Within t1 to the t6 time period, rectified current I iNaverage current I iN_AVGwith commutating voltage V iNessence homophase.Described by composition graphs 9B, input current I aCwith input voltage V aCessence homophase, thus the power factor correcting drive circuit 900, and then improve power supply quality.
Figure 13 shows that according to an embodiment of the invention for driving the method flow diagram 1300 of the drive circuit of load (such as, for driving the drive circuit 900 or 1000 of light-emitting diode chain 208).Composition graphs 9A to Figure 12 is described by Figure 13.The concrete steps that Figure 13 is contained only exemplarily.That is, the present invention is also applicable to the step that performs other rational steps or improve Figure 13.
In step 1302, receive input voltage (such as, commutating voltage V iN) and input current (such as, rectified current I iN).In step 1304, input voltage is converted into output voltage, for load (such as, LED source) provides electric energy.In step 1306, according to the electric current of drive singal (such as, drive singal 962) control flow check through energy-storage units (such as, energy-storage units 214), to regulate the electric current flowing through load.
In step 1308, the first induced signal (such as, average current induced signal IAVG) that instruction flows through the electric current of load is received.In one embodiment, the first induced signal flows through the second induced signal filtering of energy-storage units electric current by instruction and obtains.In step 1310, sawtooth signal is produced according to drive singal.
In step 1312, by sawtooth signal and the first actuated signal control drive singal, to regulate the electric current flowing through load to target current value, and pass through average current and the input voltage essence homophase of control inputs electric current, to correct the power factor of drive circuit.In one embodiment, the difference according to the first induced signal and reference signal produces error signal, and reference signal instruction flows through the target current value of LED source.Relatively sawtooth signal and error signal, and the monitor signal receiving instruction energy-storage units situation.If when the electric current that monitor signal instruction flows through energy-storage units is reduced to preset value, switch drive singal to the first state, and according to the comparison value of sawtooth signal and error signal, switch drive singal to the second state.When drive singal is in the first state, increase the electric current flowing through energy-storage units, when drive singal is in the second state, reduce the electric current flowing through energy-storage units.In one embodiment, if the electric current flowing through LED source remains on target current value, then the time that sawtooth signal is increased to error signal from preset value is constant.
Figure 14 shows that the circuit diagram of the light source driving circuit 1400 according to another embodiment of the present invention.Number identical parts in Figure 14 with Fig. 2 and Fig. 3 and there is similar function.In the example of Figure 14, light source driving circuit 1400 comprises rectifier 204, power converter 1406, filter 212 and controller 1410.Such as, rectifier 204 can be the bridge rectifier comprising diode D1-D4.Rectifier 204 receives the alternating voltage from power supply 202.Power converter 1406 receive rectifier 204 export commutating voltage and produce output power be load (as light-emitting diode chain 208) power supply.
In the example of Figure 14, power converter 1406 falls booster converter (buck-boost converter), and it receives input voltage (such as, the commutating voltage of rectifier 204 output) and produces the output voltage being greater than or less than input voltage.Booster converter falls in utilization, and light source driving circuit 1400 can adjust output voltage more neatly according to different loading demands.In addition, the light source driving circuit 1400 falling booster converter is adopted to have relatively low total harmonic distortion and relative high power factor.
In one embodiment, power converter 1406 comprises electric capacity 1408, switch 1416, resistance 1420, energy-storage units 1414, current monitor 1418(such as resistance 1418), diode 1412 and electric capacity 1424.Power converter 1406 receives input voltage and input current, and provides electric energy for light-emitting diode chain 208.Switch 1416 is controlled by drive singal.Controller 1410 receives the induced signal IAVG that instruction flows through the electric current of light-emitting diode chain 208, and carrys out control switch 1416, to regulate the electric current flowing through light-emitting diode chain 208 according to induced signal IAVG generation drive singal.
More specifically, in one embodiment, energy-storage units 1414 is coupled between the ground of switch 1416 and light source driving circuit 1400.Energy-storage units 1414 is coupled to the common node 1433 between switch 1416 and current monitor 1418.Common node 1433 for controller 1410 provide with reference to ground.In one embodiment, the reference ground of controller 1410 is different with the ground of light source driving circuit 1400.In the example of Figure 14, energy-storage units 1414 comprises inductance 1402 and inductance 1404.Inductance 1402 is with being coupled in the reference of controller 1410 and between the ground of light source driving circuit 1400.The electric current of energy-storage units 1414 flows through inductance 1402.Inductance 1404 and inductance 1402 electromagnetic coupled, for monitoring the situation of inductance 1402.More specifically, inductance 1402 and inductance 1404 are all connected to common node 1433.
Switch 1416 controls the electric current of energy-storage units 1414.The resistance 1420 be coupled between switch 1416 and energy-storage units 1414 provides induced signal VSEN to controller 1410, and induced signal VSEN indicates the state of energy-storage units 1414.If the voltage of induced signal VSEN is greater than preset voltage value (such as 1.1V), controller 1410 cut-off switch 1416.
One end of current monitor 1418 is connected with node 1433, and the other end is connected with the negative electrode of diode 1412.The induced signal ISEN of the transient current (such as instruction flows through the transient current of diode 1412 when switch 1416 disconnects) that current monitor 1418 provides instruction to flow through power converter 1406.When switch 1416 is connected, due to diode 1412 reverse bias, electric current is not had to flow through diode 1412.The induced signal IAVG that instruction flows through the electric current of light-emitting diode chain 208 obtains from induced signal ISEN.More specifically, the filter 212 be coupled between current monitor 1418 and controller 1410 produces according to induced signal ISEN the induced signal IAVG that instruction flows through the electric current of light-emitting diode chain 208.In one embodiment, filter 212 comprises resistance 320 and electric capacity 322.In the example of Figure 14, induced signal ISEN instruction flows through the transient current of power converter 1406, such as, flow through the transient current of diode 1412.The average current flowing through diode 1412 equals the electric current flowing through light-emitting diode chain 208.But in other embodiments, induced signal ISEN can indicate the transient current of other element flowing through power converter 1406, is not limited to the embodiment shown in Figure 14.
Controller 1410 receives induced signal IAVG and makes the average current flowing through diode 1412 equal target current value by being switched on or switched off switch 1416.Electric capacity 1424 filtering flows through the ripple of the electric current of light-emitting diode chain 208, thus the electric current making to flow through light-emitting diode chain 208 relatively steadily and equal to flow through the average current of diode 1412.Therefore, the electric current flowing through light-emitting diode chain 208 is equal with target current value." equal from target current value " refers to that the electric current flowing through light-emitting diode chain 208 can be different a little but within rational scope with target current value herein, thus the current ripples caused by undesirable circuit element can be left in the basket.
In the example of Figure 14, the port of controller 1410 comprises ZCD, GND, DRV, VDD, CS, COMP and FB.Port FB is coupled with current monitor 1418 by filter 212, flows through the induced signal IAVG of the average current of diode 1412 for receiving instruction.The average current flowing through diode 1412 equals the electric current flowing through light-emitting diode chain 208.So, the port FB of controller 1410 receives the induced signal IAVG that instruction flows through the electric current of light-emitting diode chain 208.Port ZCD is coupled with inductance 1404, such as, for receiving the monitor signal AUX of the situation (such as, whether the electric current flowing through inductance 1402 is reduced to the first pre-set current value, zero ampere) of instruction energy-storage units 1414.The electric current of energy-storage units 1414 is controlled by switch 1416.If the electric current flowing through inductance 1402 is reduced to the first pre-set current value, such as zero ampere, controller 1410 turn on-switch 1416.Whether monitor signal AUX also indication light diode chain 208 can be in open-circuit condition.Port DRV is coupled with switch 1416.Controller 1410 produces drive singal (as pulse width modulating signal PWM1) according to induced signal IAVG and monitor signal AUX at port DRV.Pulse width modulating signal PWM1 control flow check through the transient current of power converter 1406, such as, flows through the transient current of diode 1412, thus regulates the electric current flowing through light-emitting diode chain 208.In one embodiment, pulse width modulating signal PWM1 has the first state (as logical one) and the second state (as logical zero).If pulse width modulating signal PWM1 is in the first state, switch 1416 is connected; And if pulse width modulating signal PWM1 is in the second state, switch 1416 disconnects.When drive singal is in the first state, the electric current flowing through inductance 1402 increases; And when drive singal is in the second state, the electric current flowing through inductance 1402 reduces.Port VDD is coupled with inductance 1404, for receiving the electric power of self-inductance 1404.Port CS is coupled with resistance 1420, for receiving the induced signal VSEN of the state (whether the energy stored in such as energy-storage units 1414 increases to preset energy value) of instruction energy-storage units 1414.Whether induced signal VSEN also indication light diode chain 208 can be in short-circuit condition.Port COMP is coupled by the reference of electric capacity 318 and controller 1410.Port COMP provide error signal.In the example of Figure 14, reference of port GND(also i.e. controller 1410) be connected to common node 1433 between current monitor 1418 and energy-storage units 1414.
Switch 1416 can be N-type mos field effect transistor (N-type MOSFET).The conducting state of switch 1416 is determined by the voltage difference between the grid voltage of switch 1416 and the voltage (i.e. the voltage of common node 1433) of port GND.Therefore, the pulse width modulating signal PWM1 that port DRV exports determines the state of switch 1416.When switch 1416 is connected, the reference ground of controller 1410, higher than the ground of light source driving circuit 1400, makes circuit of the present invention go for having the power supply of high voltage.
In operation, when switch 1416 is connected, electric current flows through switch 1416, resistance 1420, inductance 1402 to the ground of light source driving circuit 1400.When switch 1416 disconnects, electric current flows through inductance 1402, light-emitting diode chain 208, diode 1412 and current monitor 1418.Current monitor 1418 provides instruction to flow through the induced signal ISEN of the transient current of diode 1412.The induced signal IAVG that instruction flows through the electric current of light-emitting diode chain 208 obtains from induced signal ISEN.Therefore, in one embodiment, controller 1410 produces pulse width modulating signal PWM1 according to induced signal IAVG, with control switch 1416, makes the average current flowing through diode 1412 equal target current value.After electric capacity 1424 filtering, the electric current flowing through light-emitting diode chain 208 also equals target current value.
In one embodiment, according to monitor signal AUX, controller 1410 judges whether light-emitting diode chain 208 is in open-circuit condition.If light-emitting diode chain 208 is opened a way, then the voltage on electric capacity 1424 increases, and when switch 1416 is in off-state, the voltage at inductance 1402 two ends increases, and the voltage of monitor signal AUX also increases thereupon.Consequently, increased by the electric current of port ZCD ramp metering device 1410.Therefore, by monitor signal AUX, controller 1410 judges that whether the electric current flowing through inductance 1402 when switch 1416 is in off-state is more than the second pre-set current value (such as, 300 microamperes), thus judge whether light-emitting diode chain 208 is in open-circuit condition.
In one embodiment, according to induced signal VSEN, controller 210 judges whether light-emitting diode chain 208 is in short-circuit condition.If light-emitting diode chain 208 short circuit, the energy stored in energy-storage units 1414 increases, and the voltage of induced signal VSEN also increases thereupon.Consequently, the voltage of port CS increases thereupon.Therefore, by monitor signal VSEN, controller 1410 judges whether the voltage of monitor signal VSEN exceedes preset voltage value (such as, 1.1V), thus judge whether light-emitting diode chain 208 is in short-circuit condition.
Figure 15 shows that the structural representation of Figure 14 middle controller 1410 according to an embodiment of the invention.Number identical parts in Figure 15 with Fig. 4 and there is similar function.Figure 15 will be described in conjunction with Figure 14.
In the example of Figure 15, controller 1410 comprises error amplifier 402, comparator 404 and pulse width modulating signal generator 408.Error amplifier 402 produces error signal VEA according to reference signal SET and induced signal IAVG at port COMP.Reference signal SET indicating target current value.Wherein, the voltage of error signal VEA is less than the preset voltage value (such as, 1.1V) when judging that light-emitting diode chain 208 is in short-circuit condition.Induced signal IAVG is received by port FB, and instruction flows through the average current of diode 1412.The average current flowing through diode 1412 is made to equal target current value by the effect of error signal VEA.Comparator 404 is coupled with error amplifier 402, for comparison error signal VEA and induced signal VSEN.Induced signal VSEN is received by port CS, the state of instruction energy-storage units 1414.Monitor signal AUX is received by port ZCD, and whether the electric current that instruction flows through inductance 1402 is reduced to the first pre-set current value (being such as reduced to zero ampere).Pulse width modulating signal generator 408 is coupled with comparator 404 and port ZCD, according to output and the monitor signal AUX generation pulse width modulating signal PWM1 of comparator 404.Pulse width modulating signal PWM1 is by the conducting state of port DRV control switch 1416.
In operation, when pulse width modulating signal PWM1 is in the first state (as logical one), switch 1416 is connected.When switch 1416 is connected, electric current flows through switch 1416, resistance 1420, inductance 1402 to the ground of light source driving circuit 1400.The electric current flowing through inductance 1402 increases gradually, and the voltage of induced signal VSEN is increased gradually.In one embodiment, when switch 1416 is connected, the voltage of monitor signal AUX is negative value.Inner at controller 1410, error signal VEA and induced signal VSEN compares by comparator 404.When the voltage of induced signal VSEN exceedes the voltage of error signal VEA, the output of comparator 404 is logical zero, otherwise the output of comparator 404 is logical one.In other words, the output of comparator 404 is a series of pulse.Under the effect of the trailing edge of comparator 404 output, pulse width modulating signal generator 408 generation has the pulse width modulating signal PWM1 of the second state (as logical zero) with cut-off switch 1416.In one embodiment, when switch 1416 disconnects, the voltage of monitor signal AUX be on the occasion of.When switch 1416 disconnects, electric current flows through inductance 1402, light-emitting diode chain 208, diode 1412 and current monitor 1418.The electric current flowing through inductance 1402 reduces gradually, and therefore the voltage of induced signal VSEN reduces gradually.If the electric current that monitor signal AUX instruction flows through inductance 1402 is reduced to the first pre-set current value (as being reduced to zero ampere), pulse width modulating signal PWM1 switches to the first state (as logical one).In one embodiment, when the electric current flowing through inductance 1402 is reduced to the first pre-set current value (as being reduced to zero ampere), the voltage of monitor signal AUX can produce a trailing edge.Under the effect of monitor signal AUX trailing edge, the generation of pulse width modulating signal generator 408 has the pulse width modulating signal PWM1 of the first state (as logical one) with turn on-switch 1416.
In one embodiment, if monitor signal AUX indicates the electric current flowing through inductance 1402 to increase to the second pre-set current value (such as, 300 microamperes) when switch 1416 disconnects, pulse width modulating signal PWM1 remains on the second state (as logical zero).Controller 1410 judges that light-emitting diode chain 208 is in open-circuit condition.In one embodiment, if the voltage of monitor signal VSEN exceedes preset voltage value (such as, 1.1V), controller 1410 judges that light-emitting diode chain 208 is in short-circuit condition.When controller 1410 judges that light-emitting diode chain 208 is in open-circuit condition or short-circuit condition, pulse width modulating signal PWM1 remain on the second state (as logical zero) with cut-off switch 1416 until abnormality no longer exist.
In one embodiment, the duty ratio of pulse width modulating signal PWM1 is determined by error signal VEA.If the voltage of induced signal IAVG is less than the voltage of reference signal SET, then error amplifier 402 increases the voltage of error signal VEA to increase the duty ratio of pulse width modulating signal PWM1, thus the average current flowing through diode 1412 is increased, until the voltage of induced signal IAVG increases to the voltage of reference signal SET.If the voltage of induced signal IAVG is greater than the voltage of reference signal SET, then error amplifier 402 reduces the voltage of error signal VEA to reduce the duty ratio of pulse width modulating signal PWM1, thus the average current flowing through diode 1412 is reduced, until the voltage of induced signal IAVG is reduced to the voltage of reference signal SET.Like this, the average current flowing through diode 1412 can be adjusted to equal with target current value.
Figure 16 shows that the circuit diagram according to the present invention's light source driving circuit 1600 of another embodiment again.Number identical parts in Figure 16 with Figure 14 and there is similar function.Except the structure of power converter 1406, in Figure 16, in the circuit diagram of light source driving circuit 1600 and Figure 14, the circuit diagram of light source driving circuit 1400 is similar.In the example of Figure 16, energy-storage units 1414 comprises inductance 1402.In one embodiment, power converter 1406 also can comprise the Zener diode D5 be coupled between inductance 1402 and controller 1410.Zener diode D5 forms bias level shifter to apply level shift (bias voltage) to the supply voltage of controller 1410, thus provides suitable power supply to controller 1410 via port VDD from inductance 1402.
Figure 17 shows that the circuit diagram according to the present invention's light source driving circuit 1700 of another embodiment again.Number identical parts with Fig. 9 A, Figure 10 and Figure 14 in Figure 17 and there is similar function.Except the structure of power converter 1406, in Figure 17, in the circuit diagram of light source driving circuit 1700 and Figure 10, the circuit diagram of light source driving circuit 1000 is similar.
In one embodiment, power converter 1406 comprises the input capacitance 1408 being coupled in power line 912.Input capacitance 1408 reduces commutating voltage V iNripple, with smooth commutation voltage V iNwaveform.In one embodiment, input capacitance 1408 has relatively little capacitance to help to eliminate or reduce commutating voltage V iNthe distortion of waveform.In addition, in one embodiment, because input capacitance 1408 is less, the electric current flowing through input capacitance 1408 can be ignored.Therefore, when switch 1416 is connected, the electric current I of switch 1416 is flowed through 1402with the rectified current I flowed out from rectifier 204 iNroughly equal.
The class of operation of the power converter 1406 in Figure 17 and the power converter 1406 in Figure 14 seemingly.In one embodiment, according to the conducting state of switch 1416, electric current I 1412flow through diode 1412 and electric current I 1402flow through inductance 1402.More specifically, controller 910 produces drive singal 962(as pulse width modulating signal on DRV port), be switched on or switched off with control switch 1416.When switch 1416 is connected, electric current I 1402flow out from power line 912, flow through switch 1416, resistance 1420, inductance 1402 to the ground of light source driving circuit 1700.Due to diode 1412 reverse bias, electric current is not had to flow through diode 1412.During switch 1416 is connected, electric current I 1402can increase gradually according to formula (3):
△I 1402=V IN×T ON/L 1402(3)，
Wherein, T oNrepresent the time that switch 1416 is connected, △ I 1402represent electric current I 1402variable quantity, L 1402represent the inductance value of inductance 1402, and the voltage drop of the voltage drop of switch 1416 and resistance 1420 can be left in the basket.In one embodiment, controller 910 controls drive singal 962, makes T turn-on time in each switching cycle (i.e. the cycle of drive singal) of switch 1416 oNit is a steady state value.So, electric current I 1402variable quantity △ I 1402with commutating voltage V iNproportional.In one embodiment, electric current I is worked as 1402when being reduced to the first preset value (as zero ampere), switch 1416 is connected.Therefore, electric current I 1402peak value and commutating voltage V iNproportional.
At each switching cycle, switch 1416 is at connection T oNbe disconnected after time period.When switch 1416 disconnects, electric current I 1412flow through inductance 1402, light-emitting diode chain 208, diode 1412 and current monitor 1418.Accordingly, electric current I 1412reduce according to formula (4):
△I 1412=△I 1402=V OUT×T OFF/L 1402(4)。
Wherein, T oFFrepresent the time that switch 1416 disconnects, △ I 1412represent electric current I 1412variable quantity, and the voltage drop of the voltage drop of diode 1412 and current monitor 1418 can be left in the basket.In one embodiment, when switch 1416 is connected, rectified current I iNwith electric current I 1402equal, when switch 1416 disconnects, rectified current I iNequal zero ampere.
In one embodiment, power converter 1406 comprises electric capacity 1424.Electric capacity 1424 can be the electric capacity with relatively large capacitance.So, flow through the electric current I of light-emitting diode chain 208 oUTequal electric current I 1412mean value.
The class of operation of the controller 910 in Figure 17 and the controller 910 in Figure 10 seemingly.In fig. 17, controller 910 comprises port ZCD, GND, DRV, VDD, CS, COMP and FB.Port ZCD is coupled with inductance 1404, such as, for receiving the monitor signal AUX of the situation (such as, whether the electric current flowing through inductance 1402 is reduced to the first pre-set current value, zero ampere) of instruction inductance 1402.Whether monitor signal AUX also indication light diode chain 208 can be in open-circuit condition.Port GND is coupled in the common node 1433 between resistance 1418 and energy-storage units 1414.Port DRV is coupled with switch 1416 and produces drive singal 962(as pulse width modulating signal PWM1) to be switched on or switched off switch 1416.Port VDD is coupled with inductance 1404 and receives the electric power of self-inductance 1404.Port COMP is coupled by the reference of electric capacity 318 and controller 910.Port FB to be coupled with current monitor 1418 by filter 212 and to receive the electric current I indicating and flow through light-emitting diode chain 208 oUTinduced signal IAVG.
The going sawtooth signal generator 902 being coupled in controller 910 produces sawtooth signal 960 for the drive singal 962 according to DRV port on CS port.Such as, going sawtooth signal generator 902 comprises and is coupled in resistance 1016 between DRV port and CS port and parallel with one another and diode 1018, also comprise be coupled in CS port and controller 910 reference ground between and resistance 1012 parallel with one another and electric capacity 1014.Sawtooth signal 960 changes according to drive singal 962.More specifically, in one embodiment, drive singal 962 is pulse width modulating signal.When drive singal 962 is logic high, electric current I 1 flows out from DRV port, through resistance 1016, flows into electric capacity 1014.Therefore, electric capacity 1014 is charged, the voltage V of sawtooth signal 960 960increase.When drive singal 962 is logic low, electric current I 2 flows out from electric capacity 1014, through diode 1018, and flows into DRV port.Therefore, electric capacity 1014 discharges, voltage V 960be reduced to zero volt.Going sawtooth signal generator 902 can also comprise other assemblies, is not limited to the embodiment shown in Figure 17.
Advantageously, controller 910 produces drive singal 962 according to sawtooth signal 960 and induced signal IAVG.Controller 910 regulates the electric current I flowing through light-emitting diode chain 208 oUTto target current value and by controlling rectified current I iNaverage current I iN_AVGwith commutating voltage V iNessence homophase, to correct the power factor of drive circuit 1700.
The signal waveforms that Figure 18 shows that light source driving circuit (as drive circuit 1700) generation in accordance with another embodiment of the present invention or receive.Composition graphs 4, Fig. 9 A, Fig. 9 B and Figure 17 are described by Figure 18.Figure 18 describes commutating voltage V iN, rectified current I iN, rectified current I iNaverage current I iN_AVG, flow through the electric current I of inductance 1402 1402, flow through the electric current I of light-emitting diode chain 208 oUT, instruction flows through the electric current I of diode 1412 1412induced signal ISEN, error signal VEA, sawtooth signal 960 and drive singal 962.There is the light source driving circuit 1700 falling booster converter there is relatively low total harmonic distortion and relative high power factor.
As shown in figure 18, commutating voltage V iNit is the sine wave signal after rectification.In the t1 moment, drive singal 962 becomes the first state (as logic high).Therefore, switch 1416 is connected, and flows through the electric current I of inductance 1402 1402increase.Due to diode 1412 reverse bias, electric current is not had to flow through diode 1412.Meanwhile, sawtooth signal 960 increased in the first state (as logic high) period of drive singal 962.
In the t2 moment, when sawtooth signal 960 is increased to error signal VEA, drive singal 962 switches to the second state (as logic low).Under the effect of drive singal 962 trailing edge, sawtooth signal 960 drops to zero volt and induced signal ISEN increases to electric current I 1402peak value.Drive singal 962 cut-off switch 1416, electric current starts to flow through inductance 1402 and diode 1412, therefore electric current I 1402decline with induced signal ISEN.In other words, sawtooth signal 960 and error signal VEA determine the time T of the turn on-switch 1416 when drive singal 962 is logic high oN.
In the t3 moment, electric current I 1402and electric current I 1412be reduced to the first pre-set current value (as zero ampere), thus, drive singal 962 is switched to logic high by controller 910, with turn on-switch 1416.
In one embodiment, at commutating voltage V iNone-period in, flow through the electric current I of light-emitting diode chain 208 oUTwith electric current I 1412mean value equal or proportional.In conjunction with the description of Figure 11, controller 910 is by electric current I oUTbe adjusted to the target current value represented by reference signal SET.In addition, as shown in figure 18, electric current I is represented 1412induced signal ISEN during t1 to t4 with there is during t5 to t6 identical waveform.So, electric current I 1412mean value during t1 to t4 is equal with the mean value during t5 to t6.Therefore, electric current I oUTremain on target current value.In one embodiment, T oNdetermined by sawtooth signal 960 and error signal VEA.In one embodiment, due within each cycle of drive singal 962, the time that sawtooth signal 960 rises to error signal VEA from zero volt is all equal, so T oNconstant.According to formula (3), at T oNin time, electric current I 1402variable quantity △ I 1402with commutating voltage V iNproportional.So, as shown in figure 18, peak value (the i.e. electric current I of induced signal ISEN 1402peak value) with commutating voltage V iNproportional.
In one embodiment, when switch 1416 is connected, rectified current I iNwaveform and electric current I 1402waveform similar, and when switch 1416 disconnects, rectified current I iNequal zero ampere.Within t1 to the t6 time period, rectified current I iNaverage current I iN_AVGwith commutating voltage V iNessence homophase.Described by composition graphs 9B, controller 910 corrects the power factor of drive circuit 1700 to make AC input current I aCwith AC-input voltage V aCessence homophase.
The invention provides the drive circuit driving load.Load can be light source, such as LED source 208.The present invention is not limited thereto, and load can comprise the light source of other types or the load (as battery pack) of other types.Drive circuit comprises electric power converter and controller.Electric power converter converts input voltage to output voltage, thinks that load provides electric energy.Power converter provides instruction to flow through the induced signal of the electric current of load.Drive circuit also comprises going sawtooth signal generator, for producing sawtooth signal according to drive singal.Advantageously, controller produces drive singal according to induced signal and sawtooth signal.Drive singal control flow check, through the electric current of energy-storage units, to regulate the electric current flowing through load to target current value, and passes through average current and the input voltage essence homophase of control inputs electric current, to correct the power factor of drive circuit.
Figure 19 shows that the circuit diagram of the light source driving circuit 1900 according to another embodiment of the present invention.Number identical parts in Figure 19 with Fig. 2 and Fig. 3 and there is similar function.In the example of Figure 19, light source driving circuit 1900 comprises rectifier 204, line voltage compensation circuit 1920, power converter 1906 and controller 1910.Such as, rectifier 204 can be the bridge rectifier comprising diode D1-D4.Rectifier 204 receives the alternating voltage V from power supply 202 aC.Power converter 1906 receives the input voltage V from rectifier 204 iNand produce output voltage V oUTfor load (as light-emitting diode chain 208) power supply.
In the example of Figure 19, power converter 1906 is that booster converter (quasi-resonant buck-boost converter) falls in quasi-resonance, and it receives input voltage V iNand generation is greater than or less than input voltage V iNoutput voltage V oUT.Utilize quasi-resonance to fall booster converter, light source driving circuit 1900 can adjust output voltage more neatly according to different loading demands.In addition, the light source driving circuit 1900 adopting quasi-resonance to fall booster converter has relatively low total harmonic distortion and relative high power factor.
In one embodiment, power converter 1906 comprises energy-storage units 1914, switch 1916, diode 1912, resistance 1922 and electric capacity 1924.Power converter 1906 receives input voltage V iNand input current, and provide electric energy for light-emitting diode chain 208.Switch 1916 is that the drive singal 1926 produced by controller 1910 controls.In one embodiment, energy-storage units 1914 comprises the first inductance (such as inductance 1902) and the second inductance (such as inductance 1904).The electric current of energy-storage units 1914 flows through inductance 1902, and inductance 1904 and inductance 1902 electromagnetic coupled, for monitoring the situation of inductance 1902.Electric capacity 1924 filtering flows through the ripple of the electric current of light-emitting diode chain 208, thus the electric current making to flow through light-emitting diode chain 208 relatively steadily and equal to flow through the average current of diode 1912.Those skilled in the art should understand, and the structure of the power converter 1906 shown in Figure 19 is only example and is not restriction of the present invention, and the present invention also can adopt the power converter of other structure.
Figure 20 shows that the structural representation of Figure 19 middle controller 1910.Number identical parts in Figure 20 with Figure 15 and Figure 19 and there is similar function.In the example of Figure 19 and Figure 20, controller 1910 comprises startup and low pressure lock-in circuit 401, error amplifier 2002 and pulse width modulating signal generator 2004.The port of controller 1910 comprises ZCD, GND, DRV, VDD, CS and COMP.In one embodiment, port CS is the first monitoring port, and port ZCD is the second monitoring port, and port DRV is for driving port, and port COMP is for compensating port.
Port ZCD is coupled with inductance 1904, such as, for receiving the monitor signal AUX of the situation (such as, whether the electric current flowing through inductance 1902 is reduced to the first pre-set current value, zero ampere) of instruction energy-storage units 1914.The electric current of energy-storage units 1914 is controlled by switch 1916.If the electric current flowing through inductance 1902 is reduced to the first pre-set current value (such as zero ampere), then controller 1910 utilizes drive singal 1926 to carry out turn on-switch 1916.In one embodiment, whether monitor signal AUX also indication light diode chain 208 can be in open-circuit condition.Port DRV is coupled with switch 1916.Controller 1910 produces drive singal 1926(as pulse width modulating signal according to combination monitor signal SEN and monitor signal AUX at port DRV).Drive singal 1926 control flow check through the transient current of power converter 1906, thus regulates the electric current flowing through light-emitting diode chain 208.In one embodiment, drive singal 1926 has the first state (as logical one) and the second state (as logical zero).If drive singal 1926 is in the first state, switch 1916 is connected; And if drive singal 1926 is in the second state, switch 1916 disconnects.When drive singal 1926 is in the first state, the electric current flowing through inductance 1902 increases; And when drive singal 1926 is in the second state, the electric current flowing through inductance 1902 reduces.Port VDD is coupled with inductance 1904, for receiving the electric power of self-inductance 1904.Port COMP is coupled to ground, for providing error signal to electric capacity (non-label) by electric capacity (non-label).Port GND is coupled to ground.
Be different from the controller 1410 shown in Figure 14, controller 1910 decreases port FB.Current monitor R8 is coupling in (switch 1916 is A with the common node of current monitor R8) between switch 1916 and ground, for generation of current monitor signal.The magnitude of voltage V of this current monitor signal arepresentative flows through the average current input value (that is, flowing through the current value of light-emitting diode chain 208) of inductance 1902.Therefore, this current monitor signal also indicates the size of current flowing through light-emitting diode chain 208.The common node of line voltage compensation circuit 1920(resistance R1 and R2 be made up of the first resistance (such as resistance R1) and the second resistance (such as resistance R2) is B, and magnitude of voltage is V b) be coupling between rectifier 204 and controller 1910, for generation of voltage monitoring signal, this voltage monitoring signal designation input voltage V iNsize.Note that the structure of the line voltage compensation circuit 1920 in Figure 19 is only a kind of possible example, and and unrestricted.Those skilled in the art should use other suitable line voltage compensation circuit (such as, bleeder circuit) instead after reading description of the invention.The current monitor signal produced by current monitor R8 and the voltage monitoring signal produced by line voltage compensation circuit 1920 superpose together and form combination monitor signal SEN, and its instruction flows through current value and the input voltage V of light-emitting diode chain 208 iNsize.
Controller 1910 receives combination monitor signal SEN from port CS and compares the voltage of this combination monitor signal SEN and the voltage of reference signal SET by error amplifier 2002.Reference signal SET instruction flows through the target current value of light-emitting diode chain 208.The output of error amplifier 2002 provides error signal VEA to port COMP, and error signal VEA is inputed to pulse width modulating signal generator 2004 with control switch 1916.In one embodiment, the duty ratio of drive singal 1926 that pulse width modulating signal generator 2004 exports is determined by error signal VEA.If the voltage of combination monitor signal SEN is less than the voltage of reference signal SET, then error amplifier 2002 increases the voltage of error signal VEA to increase the duty ratio of drive singal 1926, thus the average current input value flowing through inductance 1902 is increased, until the voltage of combination monitor signal SEN increases to the voltage of reference signal SET.If the voltage of combination monitor signal SEN is greater than the voltage of reference signal SET, then error amplifier 2002 reduces the voltage of error signal VEA to reduce the duty ratio of drive singal 1926, thus the average current input value flowing through inductance 1902 is reduced, until the voltage of drive singal 1926 is reduced to the voltage of reference signal SET.Like this, the average current input value (that is, flowing through the current value of light-emitting diode chain 208) flowing through inductance 1902 can be adjusted to equal with target current value.
For ease of understanding of the present invention, following idealized hypothesis will be made: assuming that the power transmission efficiency of light source driving circuit of the present invention 1900 is invariable and be similar to 100%, i.e. the input power P of power converter 1906 iNessence equals the power output P of power converter 1906 oUT.In this application, " essence equals " refers to power output P oUTequal input power P in theory iN, but in actual applications, due to the power loss in circuit, can power output P be caused oUTwith input power P iNthere is trickle difference.
Hereafter be described further by the form of formula to calculating.For quasi-resonance, booster converter falls, the ON time T of the switch 1916 in power converter 1906 oNwith T deadline oFFbe respectively: with wherein L is the inductance value of inductance 1902, I pkfor flowing through the current peak of inductance 1902, V iNfor the input voltage of power converter 1906, and V oUTfor the output voltage of power converter 1906.The duty ratio D of power converter 1906 is: switching frequency f swfor: and the average current input value (that is, flowing through the current value of light-emitting diode chain 208) flowing through inductance 1902 is
Therefore, the input power P of power converter 1906 iNwith power output P oUTfor:
P IN = P OUT = 1 2 × L × I PK 2 × f SW = D 2 × I PK × V IN = I IN - AVG × V IN = V A r 8 × V IN - - - ( 5 )
Wherein, V afor the magnitude of voltage of the current monitor signal at A point place, r8 is the resistance value of current monitor R8.As can be seen from formula (5), if input power P iNinvariable, then require V awith V iNproduct keep invariable.
In addition, can be extrapolated by Kirchhoff's second law, at the magnitude of voltage V of the current monitor signal at A point place afor:
V A = [ V SET × ( r 1 + r 2 ) - V IN × r 2 ] × 1 r 1 - - - ( 6 )
Wherein, V sETfor the magnitude of voltage of reference signal SET, r1 and r2 is respectively the resistance value of resistance R1 and R2 in line voltage compensation circuit 1920.As can be seen from formula (6), as input voltage V iNduring increase, V acan correspondingly reduce; And as input voltage V iNduring minimizing, V acan correspondingly increase.Under the suitable value condition of resistance R1, R2, can by V awith V iNproduct keep essence invariable, i.e. input power P iNinvariable.In a preferred embodiment, for the input voltage V changed between 85V-115V iN, resistance R1 and R2 can be set to 2.4 megaohms and 9.1 kilo-ohms respectively.Those skilled in the art should understand, the not restriction of the present invention of above exemplary values, according to the input voltage of different excursion, find different suitable resistance values by experience trial and error procedure (such as, the value of fixed resistance R1 and examination gather the value of resistance R2).As described above, the power transmission efficiency of light source driving circuit 1900 is invariable and be similar to 100%, i.e. the power output P of power converter 1906 oUTalso invariable.
With input power P iNangle, owing to have employed line voltage compensation circuit 1920, by regulating resistance R1 and R2 wherein, make magnitude of voltage (the i.e. V of current monitor signal a) and flow through light-emitting diode chain 208 current value all with input voltage V iNinversely.Namely as input voltage V iNduring increase, the magnitude of voltage V of current monitor signal acorrespondingly reduce (as can be seen from formula (6)), the average current input value therefore flowing through inductance 1902 and the current value flowing through light-emitting diode chain 208 also correspondingly reduce.On the contrary, as input voltage V iNduring reduction, the magnitude of voltage V of current monitor signal acorrespondingly increase (as can be seen from formula (6)), the average current input value therefore flowing through inductance 1902 and the current value flowing through light-emitting diode chain 208 also correspondingly increase.The input power P of power converter 1906 iNequal input voltage V iN(increase or reduce) is multiplied by the average current input value (reduce or increase) and the power output P of power converter 1906 that flow through inductance 1902 oUTequal input power P iN.Therefore, by utilizing line voltage compensation circuit 1920 can reduce input voltage V iNchange to the input power P of power converter 1906 iNwith power output P oUTimpact, thus meet the special applications requirement of client.Preferably, under the suitable value condition of resistance R1, R2, line voltage compensation circuit 1920 even can help to eliminate input voltage V iNchange to the input power P of power converter 1906 iNwith power output P oUTimpact, i.e. input power P iNwith power output P oUTkeep invariable.
Figure 21 is depicted as the circuit diagram of the light source driving circuit 2100 according to another embodiment of the present invention.Number identical parts in Figure 21 with Figure 19 and there is similar function.In Figure 21, in the circuit diagram of light source driving circuit 2100 and Figure 19, the circuit diagram of light source driving circuit 1900 is similar, and difference is, the light source driving circuit 2100 in Figure 21 also comprises temperature-compensation circuit 2120.Temperature-compensation circuit 2120 is coupled in the port CS of controller 1910.
The common node of temperature-compensation circuit 2120(resistance R3 and R4 be made up of the 3rd resistance (such as resistance R3) and the 4th resistance (such as resistance R4) is C, and node voltage value is V c) be coupling between line voltage compensation circuit 1920 and controller 1910, for generation of temperature monitoring signal, the ambient temperature of this temperature monitoring signal designation light source driving circuit 2100.In one embodiment, resistance R4 is semistor, when the ambient temperature of light source driving circuit 2100 exceedes predetermined temperature value (such as, when the temperature of resistance R4 exceedes its Curie point (such as, 80 DEG C) time), the twice of resistance when the resistance of resistance R4 can increase to normal temperature (such as, 25 DEG C), increases to resistance r4 ' (r4 '=2 × r4) from resistance r4 during normal temperature.Note that the structure of the temperature-compensation circuit 2120 in Figure 21 is only a kind of possible example, and and unrestricted.Those skilled in the art should use other suitable temperature-compensation circuit (such as, bleeder circuit) instead after reading description of the invention.Similar with the principle of Figure 19, in figure 21, the current monitor signal produced by current monitor R8, the voltage monitoring signal produced by line voltage compensation circuit 1920 and the temperature monitoring signal produced by temperature-compensation circuit 2120 superpose together and form combination monitor signal SEN, and its instruction flows through size of current, the input voltage V of light-emitting diode chain 208 iNsize and the ambient temperature of light source driving circuit 2100.
Temperature-compensation circuit 2120 can be regarded as the auxiliary circuit of line voltage compensation circuit 1920, its objective is and is guaranteeing input power P iNwith power output P oUTnot by input voltage V iNthe impact of change simultaneously, avoids light source driving circuit 2100 to suffer damage because ambient temperature is too high.When ambient temperature increases to a certain degree (such as, increasing to the Curie point of resistance R4), the resistance of resistance R4 sharply increase can cause the magnitude of voltage of combination monitor signal SEN to increase.As described above, if the voltage of combination monitor signal SEN is greater than the voltage of the reference signal SET of controller 1910 inside, then error amplifier 2002 reduces the voltage of error signal VEA to reduce the duty ratio of drive singal 1926, thus reduces the average current input value I flowing through inductance 1902 iN-AVGwith the current value flowing through light-emitting diode chain 208.As can be seen from formula (5), input power P iNwith power output P oUTwith current value I iN-AVGbe directly proportional.Therefore, controller 1910 obtains about the too high information of ambient temperature by receiving combination monitor signal SEN from port CS, thus the duty ratio of corresponding reduction drive singal 1926 reduce input power P iNwith power output P oUT.
Hereafter be described further by the form of formula to calculating.Be similar to Figure 19, the input power P of the power converter 1906 in Figure 21 iNwith power output P oUTfor:
P IN = P OUT = 1 2 × L × I PK 2 × f SW = D 2 I PK × V IN = I IN - AVG × V IN = V A r 8 × V IN - - - ( 7 )
In addition, can be extrapolated by Kirchhoff's second law, the magnitude of voltage V of A point afor:
V A = [ V SET r 4 × ( r 3 + r 4 ) - V IN ( r 3 + r 4 ) / / r 2 + r 1 × ( r 3 + r 4 ) / / r 2 ] × r 2 + ( r 3 + r 4 ) / / r 1 ( r 3 + r 4 ) / / r 1 - - - ( 8 )
Wherein, V sETfor the magnitude of voltage of reference signal SET, r1-r4 is respectively the resistance value of resistance R1-R4.As can be seen from formula (8), as input voltage V iNduring increase, V acan correspondingly reduce; And as input voltage V iNduring minimizing, V acan correspondingly increase.Under the suitable value condition of resistance R1-R4, can by V awith V iNproduct keep essence invariable, i.e. input power P iNinvariable.In a preferred fixed embodiment, for the input voltage V changed between 85V-115V iN, resistance R1-R4 can be set to respectively 2.4 megaohms, 9.1 kilo-ohms, 4.7 kilo-ohms and 4.7 kilo-ohms.Those skilled in the art should understand, the not restriction of the present invention of above exemplary values, according to the input voltage of different excursion, find different suitable resistance values by experience trial and error procedure (such as, the value of fixed resistance R1 and R2 and examination gather the value of resistance R3 and R4).Be similar to the principle in Figure 19, by magnitude of voltage (the i.e. V utilizing line voltage compensation circuit 1920 to make current monitor signal a) and flow through light-emitting diode chain 208 current value all with input voltage V iNinversely, input voltage V is reduced iNchange to the input power P of power converter 1906 iNwith power output P oUTimpact, thus meet the special applications requirement of client.Preferably, under the suitable value condition of resistance R1-R4, line voltage compensation circuit 1920 even can help to eliminate input voltage V iNchange to the input power P of power converter 1906 iNwith power output P oUTimpact, i.e. input power P iNwith power output P oUTkeep invariable.
In addition, at input voltage V iNwhen constant but ambient temperature exceedes predetermined temperature value (such as, when the temperature of resistance R4 exceedes its Curie point), the resistance of resistance R4 increases to r4 ' (r4 '=2 × r4) from r4, then formula (8) is rewritten as:
V A = [ V SET r 4 , × ( r 3 + r 4 , ) - V IN ( r 3 + r 4 , ) / / r 2 + r 1 × ( r 3 + r 4 , ) / / r 2 ] × r 2 + ( r 3 + r 4 , ) / / r 1 ( r 3 + r 4 ) / / r 1 = [ V SET 2 r 4 × ( r 3 + 2 r 4 ) - V IN ( r 3 + 2 r 4 ) / / r 2 + r 1 × ( r 3 + 2 r 4 ) / / r 2 ] × r 2 + ( r 3 + 2 r 4 ) / / r 1 ( r 3 + 2 r 4 ) / / r 1 - - - ( 9 )
When other parameter constant, the magnitude of voltage V in formula (9) abe less than the magnitude of voltage V in formula (8) a.Known according to formula (7), at input voltage V iNconstant but ambient temperature is too high (such as, increase to the Curie point of resistance R4) when, controller 1910 is made to consider ambient temperature to regulate the electric current flowing through load by utilizing temperature-compensation circuit 2120, input power can be reduced rapidly and power output suffers damage because ambient temperature is too high to avoid light source driving circuit 2100, thus meet the special applications requirement of client.
Figure 22 is depicted as the circuit diagram of the light source driving circuit 2200 according to another embodiment of the present invention.Number identical parts in Figure 22 with Figure 21 and there is similar function.In Figure 22, in the circuit diagram of light source driving circuit 2200 and Figure 21, the circuit diagram of light source driving circuit 2100 is similar, and difference is, the light source driving circuit 2200 in Figure 22 also comprises filter 2220.Filter 2220 is coupling between power supply 202 and rectifier 204.Power supply 202 produces AC-input voltage V aC(such as, V aCthere is sine wave signal) and AC input current I aC, AC input current I aCflow into filter 2220, electric current I aC' flow out from filter 2220, and flow into rectifier 204.Rectifier 204 receives AC-input voltage V by filter 2220 aC, and the V of the input voltage after rectification is provided iNwith input current I iN.
In fig. 22, by adopting the filter 2220 and controller 1910 that are coupled between power supply 202 and rectifier 204, AC input current I aCwith filtered electric current I aC' mean value equal or proportional.In theory, AC input current I aCwith AC-input voltage V aChomophase.But, in actual applications, owing to there is electric capacity in filter 2220 and power converter 1906, AC input current I aCwith AC-input voltage V aCbetween may there is trickle difference.In addition, AC input current I aCwith AC-input voltage V aCwaveform is also roughly similar.Therefore, the power factor of light source driving circuit 2200 obtains correction, thus improves the power supply quality of light source driving circuit 2200.Similar in the operation principle of the controller 1910 in Figure 22, line voltage compensation circuit 1920 and temperature-compensation circuit 2120 and Figure 19-Figure 21, does not separately repeat for simplicity's sake.
In operation, magnitude of voltage (the i.e. V by utilizing line voltage compensation circuit 1920 to make current monitor signal a) and flow through light-emitting diode chain 208 current value all with input voltage V iNinversely, input voltage V is reduced thus iNchange to the input power P of power converter 1906 iNwith power output P oUTimpact, thus meet the special applications requirement of client.Figure 23 is depicted as input power in Figure 22 and power output along with input voltage V iNthe actual waveform schematic diagram of change.Note that as shown in figure 23, input power and power output are not idealizedly completely equal.This is because in actual applications, due to the power loss in circuit, power output and input power can be caused to there is trickle difference.As can be seen from the waveform of Figure 23, although input voltage V iNincrease to 115V from 85V, but input power continually and steadily at about 8.0 watts power output continually and steadily at about 7.0 watts.This means under the effect of line voltage compensation circuit 1920 of the present invention, input power and power output can substantially by input voltage V iNthe impact of change.
In addition, by utilizing temperature-compensation circuit 2120 to make controller 1910 consider, ambient temperature regulates the duty ratio of drive singal 1926 and flows through the electric current of load, input power can be reduced rapidly and power output suffers damage because ambient temperature is too high to avoid light source driving circuit 2200, thus meet the special applications requirement of client.Figure 24 to be depicted as in Figure 22 input power and power output along with the actual waveform schematic diagram of variation of ambient temperature.Note that as shown in figure 24, input power and power output are not idealizedly completely equal.This is because in actual applications, due to the power loss in circuit, power output and input power can be caused to there is trickle difference.As can be seen from the waveform of Figure 24, before ambient temperature increases to a certain degree (such as, increasing to the Curie point 80 DEG C of resistance R4), be similar to the situation of Figure 23, input power and power output are that basic maintenance is constant.Once ambient temperature is more than 80 DEG C, then input power and power output sharply decline thus avoid light source driving circuit 2200 to suffer damage.This means, under the effect of temperature-compensation circuit 2120 of the present invention, input power and power output can decline rapidly when running into the too high situation of ambient temperature.
Embodiment and accompanying drawing are only conventional embodiment of the present invention above.Obviously, various supplement, amendment and replacement can be had under the prerequisite not departing from the present invention's spirit that claims define and invention scope.It should be appreciated by those skilled in the art that the present invention can change in form, structure, layout, ratio, material, element, assembly and other side under the prerequisite not deviating from invention criterion according to concrete environment and job requirement in actual applications to some extent.Therefore, embodiment disclosed here is only illustrative rather than definitive thereof, and scope of the present invention is defined by claims and legal equivalents thereof, and the description before being not limited thereto.

Claims (17)

1. a light source driving circuit, is characterized in that, described light source driving circuit comprises:
Fall booster converter, receive input voltage and input current from power supply and provide electric energy for load, described in fall booster converter and comprise the switch controlled by drive singal;
Line voltage compensation circuit, is coupled in described power supply, for generation of the voltage monitoring signal of the described input voltage size of instruction;
Current monitor, falls between described switch in booster converter and ground, flows through the current monitor signal of the size of current of described load for generation of instruction described in being coupled in; And
Controller, booster converter and described line voltage compensation circuit are fallen described in being coupled in, described controller receives and superposes by described voltage monitoring signal the combination monitor signal formed together with described current monitor signal, described combination monitor signal indicates described input voltage size and flows through the size of current of described load, described controller produces described drive singal to control described switch according to described combination monitor signal
Wherein, by described line voltage compensation circuit make the magnitude of voltage of described current monitor signal and flow through described load current value all with described input voltage inversely, when described input voltage increases, the magnitude of voltage of described current monitor signal correspondingly reduces and the current value flowing through described load correspondingly reduces, when described input voltage reduces, the magnitude of voltage of described current monitor signal correspondingly increases and the current value flowing through described load correspondingly increases.
2. light source driving circuit according to claim 1, it is characterized in that, described line voltage compensation circuit comprises the first resistance and the second resistance, common node between one end of wherein said first resistance and one end of described second resistance is coupled in described controller, the other end of described first resistance is coupled in described power supply, and the other end of described second resistance is coupled in described current monitor.
3. light source driving circuit according to claim 1, is characterized in that, described light source driving circuit also comprises:
Temperature-compensation circuit, is coupled between described line voltage compensation circuit and described controller, for generation of the temperature monitoring signal of the ambient temperature of the described light source driving circuit of instruction,
Wherein said combination monitor signal is superposed together by described voltage monitoring signal, described current monitor signal and described temperature monitoring signal form and indicate described input voltage size, flow through the ambient temperature of the size of current of described load and described drive circuit further, when described ambient temperature exceedes predetermined temperature value, described controller reduces the duty ratio of described drive singal and reduces described input power and described power output.
4. light source driving circuit according to claim 3, it is characterized in that, described temperature-compensation circuit comprises the 3rd resistance and the 4th resistance, common node between one end of described 3rd resistance and one end of described 4th resistance is coupled in described controller, the other end of described 3rd resistance is coupled in described line voltage compensation circuit, the other end of described 4th resistance is coupled to ground, wherein said 4th resistance is semistor, and when the temperature of described 4th resistance exceedes the Curie point of described 4th resistance, described ambient temperature is indicated to exceed described predetermined temperature value.
5. light source driving circuit according to claim 1, is characterized in that, described light source driving circuit also comprises:
Filter, be coupling in described power supply and describedly fall between booster converter, for receiving AC-input voltage and AC input current, and provide described input voltage and described input current for the described booster converter that falls, wherein, described controller corrects the power factor of described light source driving circuit to make described AC input current and described AC-input voltage essence homophase.
6. light source driving circuit according to claim 1, is characterized in that, described in fall booster converter and also comprise the energy-storage units be coupled between described power supply and described switch, the electric current of wherein said energy-storage units is by described switch control rule.
7. light source driving circuit according to claim 6, is characterized in that, described energy-storage units comprises:
First inductance, is coupled between described power supply and described switch, and the electric current of wherein said energy-storage units flows through described first inductance; And
Second inductance, with described first inductance electromagnetic coupled, the situation of described first inductance of described second inductance monitoring.
8. light source driving circuit according to claim 6, it is characterized in that, described controller also receives the monitor signal of the situation indicating described energy-storage units, wherein, described drive singal has the first state and the second state, when described drive singal is in described first state, the described electric current flowing through described energy-storage units increases; When described drive singal is in described second state, the described electric current flowing through described energy-storage units reduces; Wherein, if the described electric current that the instruction of described monitor signal flows through described energy-storage units is reduced to the first preset value, described drive singal switches to described first state from described second state.
9. light source driving circuit according to claim 1, it is characterized in that, described controller comprises error amplifier and pulse width modulating signal generator, wherein said error amplifier produces error signal according to the reference signal of described combination monitor signal and indicating target current value, and described pulse width modulating signal generator produces described drive singal according to described error signal.
10. light source driving circuit according to claim 1, is characterized in that, described load is light-emitting diode chain.
11. 1 kinds of controllers, fall booster converter for controlling, described in fall booster converter and receive input voltage and input current from power supply, and provide electric energy for load, it is characterized in that, described controller comprises:
First monitoring port, receives the combination monitor signal of the size of current indicating described input voltage size and flow through described load;
Second monitoring port, receive the monitor signal falling the situation of the energy-storage units in booster converter described in instruction, the electric current of wherein said energy-storage units is by switch control rule, if the described electric current that described monitor signal instruction flows through described energy-storage units is reduced to pre-set current value, described switch connected by described controller; And
Drive port, provide drive singal to described switch to fall the transient current of booster converter described in control flow check warp according to described combination monitor signal and described monitor signal, thus regulate the described size of current flowing through described load,
The electric current wherein flowing through described load be line voltage compensation circuit by being coupled in described combination monitoring port and with described input voltage inversely, when described input voltage increases, the electric current flowing through described load correspondingly reduces, when described input voltage reduces, the electric current flowing through described load correspondingly increases.
12. controllers according to claim 11, is characterized in that, described first monitoring port is also coupled in temperature-compensation circuit, and described first monitor signal indicates the ambient temperature of described drive circuit further.
13. controllers according to claim 12, is characterized in that, when described ambient temperature exceedes predetermined temperature value, described controller reduces the duty ratio of described drive singal and reduces described input power and described power output.
14. controllers according to claim 11, is characterized in that, described controller also comprises:
Compensate port, for providing error signal to electric capacity;
Wherein said drive singal has the first state and the second state, and when described drive singal is in the first state, the described electric current flowing through described energy-storage units increases; When described drive singal is in the second state, the described electric current flowing through described energy-storage units reduces.
15. controllers according to claim 14, is characterized in that, described controller also comprises:
Error amplifier, the reference signal according to described combination monitor signal and indicating target current value produces described error signal at described compensation port.
16. controllers according to claim 15, is characterized in that, described controller also comprises:
Pulse width modulating signal generator, is coupled in described error amplifier, produces described drive singal according to the described error signal of described error amplifier and described monitor signal.
17. controllers according to claim 11, is characterized in that, described load is light-emitting diode chain.
CN201310624881.XA 2013-11-29 2013-11-29 Light source driving circuit and controller Pending CN104684141A (en)

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GB201419030A GB201419030D0 (en) 2013-11-29 2014-10-27 Driving Circuit for light source and controller

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114442695A (en) * 2022-01-12 2022-05-06 中国工程物理研究院总体工程研究所 Power-adjustable thermal simulation device and simulation method

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114442695A (en) * 2022-01-12 2022-05-06 中国工程物理研究院总体工程研究所 Power-adjustable thermal simulation device and simulation method

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