CN111316548B - Lighting circuit and vehicle lamp - Google Patents
Lighting circuit and vehicle lamp Download PDFInfo
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- CN111316548B CN111316548B CN201880067425.0A CN201880067425A CN111316548B CN 111316548 B CN111316548 B CN 111316548B CN 201880067425 A CN201880067425 A CN 201880067425A CN 111316548 B CN111316548 B CN 111316548B
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- 230000003252 repetitive effect Effects 0.000 claims abstract description 5
- 238000001514 detection method Methods 0.000 claims description 46
- 230000007423 decrease Effects 0.000 claims description 7
- 230000009471 action Effects 0.000 claims description 4
- 238000010586 diagram Methods 0.000 description 29
- 230000004048 modification Effects 0.000 description 9
- 238000012986 modification Methods 0.000 description 9
- 239000003990 capacitor Substances 0.000 description 7
- 238000000034 method Methods 0.000 description 7
- 230000006870 function Effects 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 238000009499 grossing Methods 0.000 description 4
- 230000004313 glare Effects 0.000 description 3
- 230000003044 adaptive effect Effects 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 238000005401 electroluminescence Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000000630 rising effect Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
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- 230000017525 heat dissipation Effects 0.000 description 1
- 230000020169 heat generation Effects 0.000 description 1
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- 230000010349 pulsation Effects 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
Classifications
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B47/00—Circuit arrangements for operating light sources in general, i.e. where the type of light source is not relevant
- H05B47/10—Controlling the light source
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/30—Driver circuits
- H05B45/37—Converter circuits
- H05B45/3725—Switched mode power supply [SMPS]
- H05B45/38—Switched mode power supply [SMPS] using boost topology
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Circuit Arrangement For Electric Light Sources In General (AREA)
- Dc-Dc Converters (AREA)
Abstract
The lighting circuit (200) supplies power to the light source (110). The buck converter (220) receives the output voltage (V) of the boost converter (210) OUT1 ) A driving current (I) is supplied to the light source (110) DRV ). The boost converter (210) operates in a pulse mode during repetitive operation and during a stop, depending on the state of the buck converter (220).
Description
Technical Field
The present invention relates to a lighting circuit of a light source.
Background
Vehicle lighting fixtures are generally capable of switching between low beam and high beam. The low beam illuminates the vicinity with a predetermined illuminance, and a light distribution rule is set so as not to cause glare to the oncoming vehicle or the forward traveling vehicle, and is mainly used when traveling in urban areas. On the other hand, the high beam illuminates a wide area ahead and a far area with relatively high illuminance, and is mainly used when traveling at high speed on a road with little oncoming traffic or forward traffic. Therefore, the high beam is excellent in the visibility of the driver as compared with the low beam, but there is a problem in that glare is caused to the driver or the pedestrian of the vehicle existing in front of the vehicle.
In recent years, an ADB (Adaptive Driving Beam: adaptive head lamp) technology has been proposed that dynamically and adaptively controls a light distribution pattern of high beam according to the surrounding state of a vehicle. The ADB technology detects the presence or absence of a preceding vehicle, an oncoming vehicle, or a pedestrian in front of the vehicle, and dims or lights out an area corresponding to the vehicle or the pedestrian, thereby reducing glare to the vehicle or the pedestrian.
Fig. 1 is a circuit diagram of a vehicle lamp. The vehicle lamp 100R includes a light source 110 and a lighting circuit 200. Lighting circuit 200 supplies battery voltage V from battery 2 BAT As a power source, a driving current corresponding to the target luminance is supplied to the light source 110.
The light source 110 includes a plurality of light emitting units 112 connected in series. When Vf is the forward voltage of each stage of the light-emitting unit 112 and N is the number of stages of the light-emitting unit, the output voltage (load voltage) V of the lighting circuit 200 LOAD Must meet the requirements of
V LOAD ＞Vf×N。
The topology of the lighting circuit 200 is based on the battery voltage V BAT And output voltage V LOAD Is selected. V when N is less than or equal to 2 LOAD Is lower than the battery voltage V BAT The lighting circuit 200 may be constituted by a buck converter.
Conversely, when N+.gtoreq.3, the output voltage V LOAD The maximum value of which is higher than the battery voltage V BAT . Therefore, the lighting circuit 200 must be constituted by a boost converter, or a combination of a boost converter and a buck converter. The lighting circuit 200R includes a front-stage step-up converter 210, a rear-stage step-down converter 220, and controllers 230 and 240 thereof.
Output voltage V of boost converter 210 of the preceding stage OUT1 Stabilized to a target voltage V OUT1(REF) The target voltage is defined to satisfy V OUT1(REF) > Vf N. Controller 230 outputs voltage V OUT1 Near the target value V OUT1(REF) In the above embodiment, the boost converter 210 is subjected to constant voltage control.
The post-stage buck converter 220 receives the stabilized voltage V OUT1 As an input voltage, a driving current I is supplied to the light source 110 DRV . Controller 240 drives current I DRV Approaching the target value, for depressurizationThe converter 220 performs constant current control.
[ Prior Art literature ]
[ patent literature ]
Patent document 1: japanese patent application laid-open No. 2014-1768169
Disclosure of Invention
[ problem to be solved by the invention ]
The present inventors have studied on the lighting circuit 200R of fig. 1, and finally have recognized the following problems.
For example, vf is typically about 3V, but V is considered in consideration of its deviation and temperature characteristics OUT1(REF) Is defined as formula (1).
V OUT1(REF) ＝Vf (MAX) ×N…(1)
Vf (MAX) Is the maximum value of Vf in consideration of the deviation, temperature characteristics, and the like. For example, at n=12, vf (MAX) When=5v, V OUT1(REF) ＝60V。
If Vf is increased in consideration of margin (MAX) The step-up ratio K of the step-up converter 210 1 ＝V OUT /V IN Increasing the step-down ratio K of the step-down converter 220 2 ＝V OUT /V IN And (3) reducing.
This causes problems such as an increase in the size of components of the boost converter 210 and the buck converter 220, an increase in cost, and an increase in the amount of heat generated. The increase in the amount of heat generation causes a problem that the cost (a huge heat sink, a cooling fan, or the like) required for the heat dissipation strategy increases.
In addition, in the ADB-controlled lamp, a bypass switch SW may be provided in parallel with each light emitting unit 112 in order to perform bypass control so that each light emitting unit 112 is independently turned on/off. When a certain bypass switch SW is turned on, the current flowing in the light emitting unit 112 connected in parallel thereto bypasses the bypass switch SW, and thus turns off the light. By bypass control, the load voltage V between the two ends of the light source 110 LOAD Dynamically changing. At a certain time, when the number of light-emitting units 112 in the lamp state is N (0. Ltoreq. N), the number is
V LOAD ＝Vf×n。
Set to Vf (MAX) When= V, N =12, V is OUT1(REF) =60V. Actual load voltage V when n=1 LOAD Vf=3v. Therefore, the step-down ratio of the step-down converter 220 of the subsequent stage is K 2 =3/60=1/20, becomes very small, and the size of the inductor of the buck converter increases.
The present invention has been made in view of the above-described problems, and an exemplary object of one aspect thereof is to provide a lighting circuit and a vehicle lamp that can reduce the size of a converter.
[ means for solving the technical problems ]
One aspect of the present invention relates to a lighting circuit that supplies power to a light source. The lighting circuit includes a step-up converter and a step-down converter, and the step-down converter receives an output voltage of the step-up converter and supplies a driving current to the light source. The step-up converter operates in a pulse mode (intermittent mode) of a repetitive operation period (operation state) and a stop period (stop state) according to the state of the step-down converter.
According to this aspect, the output voltage of the step-up converter of the preceding stage is adjusted so that the relationship between the input voltage and the output voltage of the step-down converter of the following stage is appropriate, and therefore the range of the step-down ratio of the step-down converter can be limited.
The step-up converter may be brought into the operation period when the potential difference between the input and output of the step-down converter decreases to the first threshold value.
The step-up converter may be stopped when a potential difference between an input and an output of the step-down converter reaches a second threshold value higher than the first threshold value.
The operation period of the boost converter may be defined by a timer. That is, the start of the operation period may be started, and after a certain time has elapsed, the operation period may be shifted to the stop period.
The lighting circuit may further include: a voltage detection circuit that generates a detection signal corresponding to a potential difference of an input and an output of the buck converter; and a hysteresis comparator for comparing the detection signal with a threshold value and generating a pulse signal corresponding to the comparison result. The boost converter may also be controlled in accordance with the pulse signal.
The lighting circuit may further include: a voltage detection circuit that multiplies a potential difference between an input and an output of the buck converter by a coefficient switchable between 2 values to generate a detection signal; and a comparator for comparing the detection signal with a predetermined threshold value and generating a pulse signal corresponding to the comparison result. The coefficient may be changed according to the pulse signal, and the boost converter may be controlled according to the pulse signal.
Another aspect of the present invention relates to a vehicle lamp. The vehicle lamp includes a light source and any of the above-described lighting circuits.
Any combination of the above components, or the components of the present invention, or the means for expressing the mutual conversion between the methods, apparatuses, systems, and the like is also effective as the means of the present invention.
Further, the description of the item (means for solving the technical problem) does not describe all the features essential to the present invention, and therefore, a sub-combination of these described features may also be regarded as the present invention.
[ Effect of the invention ]
According to one aspect of the present invention, the size of the converter can be miniaturized.
Drawings
Fig. 1 is a circuit diagram of a vehicle lamp.
Fig. 2 is a circuit diagram of the vehicle lamp according to the first embodiment.
Fig. 3 is an operation waveform diagram of the lighting circuit.
Fig. 4 is an operation waveform diagram of the lighting circuit.
Fig. 5 is a circuit diagram of a part of a lighting circuit according to an embodiment.
Fig. 6 is a circuit diagram of a pulse controller according to an embodiment.
Fig. 7 (a) to (c) are circuit diagrams showing configuration examples of the voltage detection circuit.
Fig. 8 is a circuit diagram of a pulse controller according to an embodiment.
Fig. 9 (a) and (b) are circuit diagrams showing a configuration example of the pulse controller.
Fig. 10 (a) and (b) are circuit diagrams showing configuration examples of the boost converter and the converter controller.
Fig. 11 is a circuit diagram of a part of the lighting circuit according to the second embodiment.
Fig. 12 is a circuit diagram of a pulse controller according to an embodiment.
Fig. 13 is an operation waveform diagram of the pulse controller of fig. 12.
Fig. 14 is a circuit diagram of a boost converter and a converter controller according to modification 4.
Detailed Description
The present invention will be described below with reference to the drawings based on preferred embodiments. The same or equivalent components, parts, and processes shown in the drawings are denoted by the same reference numerals, and overlapping descriptions are appropriately omitted. The embodiments are not limited to the invention but are exemplified, and all the features described in the embodiments or combinations thereof do not necessarily represent the essence of the invention.
In this specification, the "state in which the component a is connected to the component B" includes a case in which the component a and the component B are physically and directly connected, and also includes a case in which the component a and the component B are indirectly connected via other components that do not have a substantial influence on their electrical connection states or do not impair the functions or effects achieved by their coupling.
Likewise, the "state in which the component C is provided between the component a and the component B" includes a case where the component a and the component C are directly connected, or the component B and the component C are indirectly connected via other components that do not have a substantial influence on their electrical connection states or do not impair the functions or effects achieved by their coupling.
In the present specification, reference numerals for electrical signals such as voltage signals and current signals, or circuit elements such as resistors and capacitors denote voltage values, current values, or resistance values and capacity values, as necessary.
The vertical and horizontal axes of the waveform diagrams and the timing charts referred to in the present specification are appropriately enlarged or reduced for easy understanding, and the waveforms shown are simplified, exaggerated or enhanced for easy understanding.
(first embodiment)
Fig. 2 is a circuit diagram of the vehicle lamp 100 according to the first embodiment. Fig. 2 shows the entire lamp system 1. The vehicle lamp 100 includes a light source 110 and a lighting circuit 200. The light source 110 includes a plurality of light emitting units 112_1 to 112_n connected in series. The light emitting unit 112 is, for example, an LED, and the light source 110 is also referred to as an LED bar or LED string. The light emitting unit 112 may be an LD (laser diode) or an organic EL (Electro Luminescence: electroluminescence) element. For example, each of the plurality of light emitting units 112_1 to 112_n irradiates a different area on a virtual vertical screen in front of the vehicle through an optical system not shown.
The lighting circuit 200 supplies a driving current I to the light source 110 DRV And makes it emit light.
Further, as an option, the lighting circuit 200 may have a function of individually switching on and off the plurality of light emitting units 112 (bypass control). The lighting circuit 200 may receive a control command S for instructing the light distribution pattern from a processor (ECU: electronic Control Unit: electronic control unit) not shown PTN According to the control instruction S PTN The plurality of light emitting units 112 are controlled to be turned on and off.
The lighting circuit 200 includes a boost converter 210, a buck converter 220, a converter controller 230, a converter controller 240, a pulse controller 250, and a lamp ECU270.
Light ECU270 includes a main switch 272 and a processor 274. The processor 274 can communicate with the vehicle ECU4, control the on/off of the main switch 272, or control the converter controllers 230, 240 to obtain an appropriate light distribution pattern, in accordance with control instructions or information from the vehicle ECU 4.
When the main switch 272 is on, the battery voltage V is supplied to the boost converter 210 BAT . Boost converter 210 generates control pulse S according to converter controller 230 1 Performs a switching operation to make the battery voltage V BAT Rise to generate output voltage V OUT1 。
The control method of the converter controller 230 is not particularly limited. The converter controller 230 generates a control pulse S in the operating state of the boost converter 210 1 So that the boost converter 210 supplies power greater than that required by the buck converter 220 and the light source 110 of the subsequent stage.
For example, the converter controller 230 adjusts the control pulse S by feedback 1 To make the output voltage V OUT1 Near being fixed sufficiently higher than the envisaged load voltage V LOAD Target value V of (2) OUT1(REF) . Alternatively, the control pulse S may be 1 Is fixed to a certain value.
Buck converter 220 reduces output voltage V OUT1 A driving current I is supplied to the light source 110 DRV . In one embodiment, the converter controller 240 may drive the current I DRV Near target value I REF Is to generate a control pulse S 2 The buck converter 220 is feedback controlled (constant current control). The converter controller 240 may use known techniques.
Boost converter 210 operates in a pulse mode during repetitive motion and during a stop, depending on the state of buck converter 220. The pulse controller 250 controls the voltage V according to the input voltage of the buck converter 220 IN2 (＝V OUT1 ) And output voltage V OUT2 Generates a pulse signal S defining on/off of the boost converter 210 BURST . Pulse signal S BURST To turn on the level (e.g., high), the converter controller 230 switches the boost converter 210 on and off, pulse signal S BURST At an off level (e.g., low), converter controller 230 stops switching of boost converter 210.
In one embodiment, the pulse controller 250 generates a voltage difference Δv (=v) according to the input/output of the buck converter 220 IN2 －V OUT2 ) The boost converter 210 is controlled to be turned on and off.
When the potential difference DeltaV of the input and output of the buck converter 220 decreases to the first threshold V TH1 At this time, the pulse controller 250 outputs a pulse signal S BURST The boost converter 210 is set to an on level and is set to an operating state.
When the input of buck converter 220 isThe potential difference DeltaV is raised to be higher than the first threshold value V TH1 Is a second threshold V of (2) TH2 At this time, the pulse controller 250 outputs a pulse signal S BURST The boost converter 210 is set to the off-level and is set to the stopped state.
The above is the structure of the lighting circuit 200. The operation will be described next. Fig. 3 is an operation waveform diagram of the lighting circuit 200. First, for easy understanding, the load voltage V will be described LOAD Certain situations.
In pulse signal S BURST On period T at high level ON The output power of the boost converter 210 is greater than the input power of the buck converter 220 of the subsequent stage. Thus outputting voltage V OUT1 Rising with time. At time t 1 The potential difference DeltaV reaches the second threshold V TH2 In other words the output voltage V OUT1 Reach V LOAD +V TH2 At the time, pulse signal S BURST At low level, enter the off period T OFF 。
Off period T OFF During the control pulse S 1 Stopping, the switching operation of the boost converter 210 is stopped, and the output voltage V OUT1 With a decrease in time. And at time t 2 The potential difference DeltaV decreases to a first threshold value V TH1 At the same time, in other words output voltage V OUT1 Reduced to V LOAD +V TH1 At the time, pulse signal S BURST At high level, return to on period T ON 。
The step-up converter 210 in the preceding stage thus operates in a pulse mode in which the operation is repeated and stopped, based on the potential difference between the input and output of the step-down converter 220 in the following stage.
Next, referring to fig. 4, the load voltage V will be described LOAD Action at time of change. Fig. 4 is an operation waveform diagram of the lighting circuit 200. Even at the load voltage V LOAD In the case of fluctuation, the operation is the same as that of fig. 3. By the pulse action of the boost converter 210, the output voltage V OUT2 Follow the load voltage V LOAD 。
The operation of the lighting circuit 200 is as described above. The advantages thereof are described next.
According to the followingThe lighting circuit 200 can limit the potential difference Δv between the input and output of the buck converter 220 to a predetermined range. That is, the step-down ratio K of the step-down converter 220 can be prevented 2 Is too small, the buck converter 220 can be designed smaller.
The effect is even at the load voltage V LOAD Is also useful in certain applications, in which the load voltage V LOAD The variable application, for example, the application of dimming accompanied by the bypass control is particularly effective.
In the following, a more specific configuration example or example will be described with respect to the first embodiment of the present invention in order to assist understanding of the nature or operation thereof and to clarify the same, but not to limit the scope thereof.
Example 1.1
Fig. 5 is a circuit diagram of a part of the lighting circuit 200 according to an embodiment. The buck converter 220, the converter controller 240, and the pulse controller 250 are shown in fig. 5.
The buck converter 220 includes a converter section 222 and a current smoothing filter 224. In this embodiment, the converter controller 240 stabilizes the coil current I of the converter section 222 by so-called ripple control (ripple control) L . By current sense resistor R S Detecting coil current I L . Coil current I L When the detected value of (a) reaches a certain peak threshold value, the converter controller 240 turns off the switching transistor M 1 Coil current I L When the detected value of (a) decreases to a certain valley threshold, the converter controller 240 turns on the switching transistor M 1 。
The current smoothing filter 224 removes the coil current I from the coil current I L Removing the pulsation component and taking the DC component as the driving current I DRV And is supplied to the light source 110.
The control method of the converter controller 240 is not limited to this, and the constant current control may be performed by an error amplifier, and in this case, the current smoothing filter 224 may be omitted.
Next, the structure of the pulse controller 250 will be described. The pulse controller 250 includes a voltage detection circuit 252 and a hysteresis comparator 254. The voltage detection circuit 252 generates pairsThe potential difference Δv (=v) corresponding to the input and output of the buck converter 220 IN2 －V LOAD ) Is a detection signal V of (1) S . Hysteresis comparator 254 will detect signal V S With a threshold V varying by a value of 2 THH ·V THL Comparing, generating a pulse signal S corresponding to the comparison result BURST . Lower threshold V THL Defining the first threshold V of FIGS. 3 and 4 TH1 Upper threshold V THH Defining the second threshold V of FIGS. 3 and 4 TH2 . Instead of a hysteresis comparator, 2 comparators can also be used. According to pulse signal S BURST The boost converter 210 of the preceding stage is controlled.
Fig. 6 is a circuit diagram of a pulse controller 250 of an embodiment. The voltage detection circuit 252 may also include a resistor R 11 ～R 14 And operational amplifier OA 1 Is composed of a differential amplifier. Hysteresis comparator 254 may be composed of resistors R21-R23 and operational amplifier (voltage comparator) OA 2 The composition is formed.
According to the voltage detection circuit 252 of fig. 6, the potential difference Δv can be detected with high accuracy using an operational amplifier.
Fig. 7 (a) to (c) are circuit diagrams showing configuration examples of the voltage detection circuit 252. The voltage detection circuit 252 of fig. 7 (a) includes a resistor R 51 、R 52 (resistance values are R), transistor Tr 51 、Tr 52 . V1 represents the input voltage V IN2 V2 represents the load voltage V LOAD . Transistor Tr 51 、Tr 52 Forming a current mirror circuit, a transistor Tr 51 Resistor R 51 Medium flowing current (V2-V) BE )/R。V BE The voltage between the base and emitter of the bipolar transistor is substantially constant. The current is replicated by a current mirror circuit, resistor R 52 The same current also flows, the voltage drop of which is V2-V BE . Thus, as the detection signal V S Obtain V S ＝V1－V2+V BE Which corresponds to the difference between the two voltages V1 and V2.
In fig. 7 (b), the structure of fig. 7 (a) is added with a transistor Tr 53 And resistance R 53 Emitter follower circuit of (a). Through emitter followerCircuit for detecting voltage V S Is V (V) BE Downward moving to obtain V S =v1-V2. That is to say the voltage V can be suppressed BE The influence of deviations or variations of (c).
In fig. 7 (c), a voltage dividing resistor R is provided 54 、R 55 Resistor R instead of (b) of FIG. 7 53 。
V S ＝(V1－V2)×R 55 /(R 54 +R 55 )
According to the voltage detection circuit 252 of fig. 7 (a) to (c), the voltage detection range can be enlarged, although the detection accuracy is lowered, compared with the case of using an operational amplifier. Especially at load voltage V LOAD In applications that vary widely, the configuration of fig. 6 may be difficult to use due to the limitation of the input range of the operational amplifier. In this case, the structures (a) to (c) of fig. 7 are effective.
Example 1.2
Fig. 8 is a circuit diagram of a pulse controller 250 according to an embodiment. The pulse controller 250 includes a voltage detection circuit 256 and a comparator 258. The voltage detection circuit 256 generates a detection signal V obtained by multiplying a potential difference Δv between the input and output of the buck converter 220 by a coefficient (gain) switchable between 2 values S . Comparator 258 will detect signal V S With a prescribed threshold V TH Comparing, generating a pulse signal S corresponding to the comparison result BURST 。
Fig. 9 (a) and (b) are circuit diagrams showing a configuration example of the pulse controller 250. In fig. 9 (a), the voltage detection circuit 256 has a circuit including a variable resistor R 40 And a fixed resistor R 41 Is provided. Variable resistor R 40 According to the comparison result (S BURST ) Varying between 2 values. Will variable resistance R 40 Is used as the detection voltage V S At the time, the voltage V is detected S Proportional to the potential difference Δv=v1-V2. Comparator 258 will detect signal V S And threshold V TH Comparison.
Fig. 9 (b) shows a specific configuration example of the pulse controller 250 of fig. 9 (a). Resistor R 40 Comprising a resistor R 42 、R 43 Transistor Tr 43 . Transistor Tr 43 When it is off, resistance R 40 Resistance value of (2) and R 42 Equal, transistor Tr 43 On, resistance R 40 The resistance value of (a) is resistance R 42 And R is 43 Is connected in parallel.
Transistor Tr 41 Is a voltage comparing unit. Resistor R 40 Voltage drop of (i.e. detection voltage V) S Is applied to transistor Tr 41 Is formed between the base emitters. Transistor Tr 41 Corresponding to the detected voltage V S And the base emitter voltage. Transistor Tr 41 By including a transistor Tr in the on-off state 44 Pulse signal S converted to 2 value by output stage (inverter) BURST . In addition, a transistor Tr 42 Resistor R 45 、R 46 Based on transistor Tr 41 On/off state of the transistor Tr 43 Is opened and closed.
In this example, the resistance R may be 40 Is set as a variable resistor, and the resistor R 41 Is set as a variable resistor. In addition, a transistor Tr is used 41 The voltage comparator is not limited to this, and a voltage comparator including a differential amplifier may be used.
Next, the boost converter 210 will be described.
Fig. 10 (a) and (b) are circuit diagrams showing configuration examples of the boost converter 210 and the converter controller 230. The converter controller 230 may be a commercially available controller IC. To load voltage V LOAD Maximum value V of (2) LOAD(MAX) The voltage after the margin alpha is increased is defined as the output voltage V OUT1 Target voltage V of (2) OUT1(REF) The boost converter 210 may be feedback controlled by the converter controller 230. Based on the feedback control of the converter controller 230, as the output voltage V OUT1 The limiter of (c) functions. The converter controller 230 has a pulse by pulse (pwm) current limiting function. Specifically, using sense resistor R CS Detection switch transistor M 2 And a current flowing therein. Based on the sense resistor R in each switching cycle CS When the current detection signal of the voltage drop of (a) exceeds the threshold value of the overcurrent protection, the converter controller 230 immediately controls the pulse S 1 Set low.
As shown in fig. 3 or 4, during the operation period, the output voltage V of the boost converter 210 OUT1 Lower than the target voltage V for feedback control OUT1(REF) . To output voltage V OUT Is kept at V OUT1(REF) The pulse-by-pulse current limiting operates before the desired on-time (pulse width) has ended. In other words, the suppliable power of the boost converter 210 is specified by a pulse-by-pulse period current limit, which is designed to exceed the input power of the buck converter 220.
Instead of the pulse-by-pulse current limitation, the power that can be supplied during the operation period may be defined by limiting the maximum on-duty (maximum on-time).
In the boost converter 210 of fig. 10 (a), the pulse signal S is passed through BURST Mask is supplied to the switching transistor M 2 Control pulse S of gate of (2) 1 . When pulse signal S BURST When the operation state is indicated, the logic gate 232 makes the control pulse S 1 Through a switching transistor M 2 As the gate of pulse signal S BURST When the state is stopped, the logic gate 232 switches the transistor M 2 The gate of (c) is fixed low.
In fig. 10 (b), an Enable (EN) pin is set in the converter controller 230. The inverter controller 230 is configured to stop the switching operation when a predetermined level (for example, low) is input to the EN pin. At this time, a pulse signal S is input to the EN pin BURST And (3) obtaining the product.
(second embodiment)
Fig. 11 is a circuit diagram of a part of the lighting circuit 200 according to the second embodiment. The buck converter 220 and the pulse controller 250 are shown in fig. 11.
In this embodiment, the operation period of the boost converter 210 is defined by a timer. The pulse controller 250 includes a voltage detection circuit 260, a comparator 262, and a timer 264. The voltage detection circuit 260 generates an input/output to the buck converter 220A detection signal V corresponding to the potential difference DeltaV S . The structure of the voltage detection circuit 260 may be the same as that described above.
Comparator 262 outputs a voltage detection signal V S And threshold voltage V THL And (5) comparing. Then, the voltage detection signal V is generated S Reduced to threshold V THL Trigger signal TRIG, which is set (e.g., high). The timer 264 generates a pulse signal S that becomes a predetermined level for a predetermined time from the setting of the trigger signal TRIG BURST 。
Fig. 12 is a circuit diagram of a pulse controller 250 according to an embodiment. The voltage detection circuit 260 includes a resistor R 90 、R 91 The same structure as the voltage detection circuit 256 of fig. 9 (a) is provided. Of course, the voltage detection circuit 260 may be configured similarly to the voltage detection circuits 252 of fig. 6 and 7 (a) to (c).
In addition, the comparator 262 includes a transistor Tr 91 、Tr 92 And resistance R 92 、R 93 、R 94 The same structure as the comparator 258 of fig. 9 (b). The comparator 262 may also be formed by a voltage comparator.
The timer 264 includes a transistor Tr 93 Capacitor C 91 Transistor Tr 94 . When the trigger signal TRIG is high, the transistor Tr 93 Conductive, capacitor C 91 Discharging, capacitor voltage VC 91 Zero, transistor Tr 94 Conducting. When the trigger signal TRIG is low, the transistor Tr 93 Cut-off, capacitor C 91 Via a resistor R 95 、R 96 Charging, capacitor voltage VC 91 Rising. With capacitor voltage V C91 Rise of resistance R 95 、R 96 The potential of the connection node of (1) also rises, followed by the transistor Tr 94 Cut-off. Pulse signal S BURST Corresponding to transistor Tr 94 The on/off state of (2) is represented by a stop at a high level and an operation at a low level. Transistor Tr 94 The off period of (a) corresponds to the operation period of the boost converter 210. Fig. 13 is an operation waveform diagram of the pulse controller 250 of fig. 12.
Timer 264 may also be comprised of a one-shot multivibrator (one-shot multivibrator).
The present invention has been described above based on the embodiments. This embodiment is an example, and it is understood by those skilled in the art that various modifications may be made to each component or combination of processing procedures, and that the modified examples obtained are also within the scope of the present invention. These modifications will be described below.
Modification 1
In one embodiment, buck converter 220 includes a constant current driver connected in series with light source 110, stabilizing drive current I by a constant current source DRV The converter controller 240 may use the series connection of the constant current driver and the light source 110 as a load, in which case the voltage across them is the load voltage V LOAD 。
Modification 2
In the embodiment, the pulse operation of the boost converter 210 is controlled based on the potential difference of the input and output of the buck converter 220, but is not limited thereto. From other points of view, the pulse controller 250 may generate the pulse signal S BURST The step-down ratio of the step-down converter 220 is made not to be lower than a prescribed value (so as to be included in a prescribed range).
Modification 3
In the embodiment, the load voltage V associated with the bypass control method is described LOAD The variation of (3) is not particularly limited to the load voltage V LOAD A factor of variation of (a).
Modification 4
Fig. 14 is a circuit diagram of a boost converter and a converter controller according to modification 4. PWM output pin of converter controller 230 and switching transistor M 2 A PMOS transistor 234 is provided between the gates of the transistors. The gate of PMOS transistor 234 is via resistor R 80 Is pushed up to the power pin. A transistor 236 is disposed between the gate of the switch 234 and ground. In addition, the resistance R can be 80 Is disposed between the gate and source (i.e., PWM pin) of PMOS transistor 234. The drain of PMOS transistor 234 is connected to a transistor via a resistor R 81 、R 82 Voltage dividing circuit and switching crystal of the sameTube M 2 Is connected to the gate of the transistor.
Pulse signal S BURST When high, transistor 236 turns on and the gate of PMOS transistor 234 is low. In this state, control pulse S 1 When high, PMOS transistor 234 is on and switching transistor M is on 2 The gate of (c) also goes high. Control pulse S 1 When low, PMOS transistor 234 is off, but the gate capacitance of switching transistor M2 is discharged via body diode 238 of PMOS transistor 234, switching transistor M 2 Conducting. Thus, in the pulse signal S BURST During the period of high level, according to the control pulse S 1 Make the switch transistor M 2 And (3) a switch.
When pulse signal S BURST When low, transistor 236 turns off and the gate of PMOS transistor 234 is pushed up via resistor R80. In this state, the control pulse S is independent of the PWM pin 1 High/low of (1), switching transistor M 2 The gate of (2) is low and the switching transistor (M2) remains off.
The present invention has been described in specific language based on the embodiments, but the embodiments are merely illustrative of the principles and applications of the present invention, and various modifications and arrangements of the embodiments are possible without departing from the spirit of the invention as defined in the claims.
[ description of reference numerals ]
100 … vehicle light, 110 … light source, 112 … light emitting unit, 200 … lighting circuit, 210 … boost converter, 220 … buck converter, 222 … converter section, 224 … current smoothing filter, 230, 240 … converter controller, 250 … pulse controller, 252 … voltage detection circuit, 254 … hysteresis comparator, 256 … voltage detection circuit, 258 … comparator, 260 … voltage detection circuit, 262 … comparator, 264 … timer, 270 … light ECU, 272 … main switch, 274 … processor.
[ Industrial availability ]
The present invention relates to a lighting circuit of a light source.
Claims (6)
1. A lighting circuit that supplies power to a light source, the lighting circuit comprising:
a boost converter; and
a buck converter for receiving an output voltage of the boost converter, supplying a driving current to the light source,
the boost converter operates in a pulse mode during repetitive motion and during a stop according to the state of the buck converter,
when the potential difference of the input and output of the buck converter decreases to a first threshold value, the boost converter enters into an action period,
the step-up converter enters a stop period when a potential difference of an input and an output of the step-down converter reaches a second threshold value higher than the first threshold value.
2. The lighting circuit of claim 1, further comprising:
a voltage detection circuit that generates a detection signal corresponding to a potential difference of an input and an output of the buck converter; and
a hysteresis comparator for comparing the detection signal with a threshold value to generate a pulse signal corresponding to the comparison result,
the boost converter is controlled in accordance with the pulse signal.
3. The lighting circuit of claim 1, further comprising:
a voltage detection circuit that generates a detection signal obtained by multiplying a potential difference between an input and an output of the buck converter by a coefficient switchable between 2 values; and
a comparator for comparing the detection signal with a predetermined threshold value to generate a pulse signal corresponding to the comparison result,
the coefficient is varied in accordance with the pulse signal, and the boost converter is controlled in accordance with the pulse signal.
4. The lighting circuit of claim 3, wherein,
the voltage detection circuit includes a variable voltage division circuit that divides a potential difference of an input and an output of the buck converter.
5. A lighting circuit that supplies power to a light source, the lighting circuit comprising:
a boost converter; and
a buck converter for receiving an output voltage of the boost converter, supplying a driving current to the light source,
the boost converter operates in a pulse mode during repetitive motion and during a stop according to the state of the buck converter,
when the potential difference of the input and output of the buck converter decreases to a first threshold value, the boost converter enters into an action period,
after the step-up converter enters the operation period, the step-up converter shifts to a stop period when a predetermined time measured by a timer elapses.
6. A vehicle lamp, comprising:
a light source; and
the lighting circuit of any one of claims 1 to 5.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2017200332 | 2017-10-16 | ||
| JP2017-200332 | 2017-10-16 | ||
| PCT/JP2018/038176 WO2019078127A1 (en) | 2017-10-16 | 2018-10-12 | Lighting circuit and vehicle lamp tool |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN111316548A CN111316548A (en) | 2020-06-19 |
| CN111316548B true CN111316548B (en) | 2024-01-23 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201880067425.0A Active CN111316548B (en) | 2017-10-16 | 2018-10-12 | Lighting circuit and vehicle lamp |
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| Country | Link |
|---|---|
| JP (1) | JPWO2019078127A1 (en) |
| CN (1) | CN111316548B (en) |
| WO (1) | WO2019078127A1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11388793B2 (en) * | 2020-07-28 | 2022-07-12 | Ch Lighting Technology Co., Ltd. | Dimmable lighting apparatus |
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| JP6118316B2 (en) * | 2011-06-17 | 2017-04-19 | フィリップス ライティング ホールディング ビー ヴィ | DC-DC driver device with input and output filters for driving a load, in particular an LED unit |
| JP2015170534A (en) * | 2014-03-07 | 2015-09-28 | パナソニックＩｐマネジメント株式会社 | Lighting device and luminaire |
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2018
- 2018-10-12 JP JP2019549250A patent/JPWO2019078127A1/en active Pending
- 2018-10-12 CN CN201880067425.0A patent/CN111316548B/en active Active
- 2018-10-12 WO PCT/JP2018/038176 patent/WO2019078127A1/en active Application Filing
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| JPH0686539A (en) * | 1992-09-03 | 1994-03-25 | Toyo Electric Mfg Co Ltd | Converter circuit |
| CN1249654A (en) * | 1998-09-21 | 2000-04-05 | 株式会社村田制作所 | Piezoelectric transformer inverter |
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Also Published As
| Publication number | Publication date |
|---|---|
| CN111316548A (en) | 2020-06-19 |
| WO2019078127A1 (en) | 2019-04-25 |
| JPWO2019078127A1 (en) | 2020-09-17 |
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