法国专利FR3017347A1 LAMP FOR VEHICLE, ITS CONTROL DEVICE AND ITS CONTROL METHOD

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专利摘要:
A current controller (42) compares a first coil current IL1 flowing in an output induction coil (L1) with a first upper threshold value IREFH and a first lower threshold value IREFL. A current limiter (44) compares a second coil current IL2 flowing in an input inductor (L2) with a second upper threshold value IPEAKH and a second lower threshold value IPEAKL. A cycle controller (46) (i) switches a switching transistor (M1) based on the first coil current IL1 in a cycle in which the first coil current IL1 exceeds the first upper threshold value IREFH before the second coil current IL2 exceeds the second upper threshold value IPEAKH. According to the current controller (42), it is possible to stabilize the output current and limit the current.
公开号:FR3017347A1
申请号:FR1551142
申请日:2015-02-12
公开日:2015-08-14
发明作者:Masayasu Ito；Takao Muramatsu；Syouhei Yanagizu
申请人:Koito Manufacturing Co Ltd；
IPC主号:

专利说明:

[0001] TECHNICAL FIELD The present invention relates to a vehicle lamp used in a vehicle or the like. STATE OF THE ART As a light source of a vehicle lamp, the replacement of a halogen lamp or a high intensity discharge lamp by a semiconductor device such as a light emitting diode (LED) or a laser diode (DL) has progressed in the associated art. A control circuit which controls such a semiconductor light source (hereinafter simply referred to as light source) comprises a converter which amplifies and attenuates an input voltage such as the voltage of a battery, and delivers the voltage to the light source and a controller that controls the converter. The controller detects the output current of the converter and performs a switching feedback control of the converter so that the output current approaches a current value corresponding to a target luminance. Figure 1 is a diagram illustrating a vehicle lamp configuration according to the associated technique. Figs. 2A and 2B are operating waveform diagrams of a vehicle lamp 1r. Referring to Fig. 1, the vehicle lamp 1r comprises a light source 10 and a control device 20r. The voltage VBAT of a battery 2 is applied to the input of the vehicle lamp ir via a switch 4. The control device 20r comprises a converter 30 and a controller 40r. The converter 30 is for example a down converter 30 and decreases the input voltage VIN and delivers the voltage to the light source 10 which is a load. The converter 30 mainly comprises an input capacitor C11, a switching transistor M11, a rectifying diode D11, an induction coil L11 and an output capacitor C12. The controller 40r detects the output current lm-flowing in the light source 10 and controls the duty cycle of the switching transistor switching M11 so that the output current I 0 -r s approach of a target value corresponding to the luminance. A current detection resistor R11 is provided on the path of a coil current IL11 to detect the coil current Li corresponding to the output current IcuT. In the current detection resistor (hereinafter referred to simply as the sense resistor) R11, there is a voltage drop (hereinafter referred to simply as sense voltage) VR11 which is proportional to the coil current. The coil current IL11 is a pulse current depending on the switching of the switching transistor M11 and the output current Toul- is the current obtained by smoothing the coil current IL11. The controller 40r stabilizes the IL11 coil current in a target range by means of a so-called hysteresis control. The controller 40r deactivates the switching transistor M11 when the detection voltage VRii reaches the upper threshold value IREFH of the target range and activates the switching transistor M11 when the detection voltage VRii decreases to the lower threshold value IREFL of the target range. An aspect of the coil current which is stabilized in the target range is illustrated in Figure 2A.
[0002] PRIOR ART DOCUMENT Patent Document 1: 3P-A-2007-126041 SUMMARY OF THE INVENTION Problem that the invention proposes to solve: To improve the reliability of a control device 20r, a protection against overcurrents are necessary. Consequently, a controller 40r compares the input current Imi1 flowing in the switching transistor M11 with a predetermined threshold value (the set being called a current limit value) IPEAK, deactivates the switching transistor M11 when the current 'mi reaches the IPEAK threshold value, and limits the input current. Specifically, a detection resistor R12 is provided on the path of the current Imi flowing in the switching transistor M11. In the detection resistor R12, a voltage drop (detection voltage) appears, which is proportional to the current Imii. The controller 40r compares the sense voltage VR12 with a threshold value voltage VPEAK corresponding to the predetermined threshold value IpEAK, and deactivates the switching transistor M11 when VR12 is greater than VPEAK. As a consequence of studying the vehicle lamp 1r of FIG. 1, the present inventor has succeeded in recognizing the following problems. In Fig. 2B, an operating waveform is illustrated in a state where the current limit is applied. At time t0, IL11 decreases to a lower threshold value IREFL and the M11 switching transistor is activated. At instant t1 immediately following, when the input current IM11 reaches a peak value IpEAK, the switching transistor M11 is deactivated. When this cycle continues, the switching frequency becomes high compared to that of Figure 2A. Considering that a vehicle lamp 1 is mounted on a vehicle, the switching noise of a few MHz disturbs the other devices mounted on the vehicle (EMI electromagnetic disturbance). In addition, as the switching frequency increases, the switching loss in the DC / DC converter increases. As a result, the efficiency decreases or the reliability of the circuit element 20 is affected. To solve this problem, when the input current N11 reaches the peak value IpEAK, the command to maintain the deactivated state of the switching transistor M11 during a predetermined deactivation time can be considered. However, in this case, a dedicated circuit is needed. In addition, when the deactivation time becomes long, the increase of the switching frequency in the current limit state can be suppressed, but it is difficult to stabilize the output current Joui in the target range. The present invention has been made with this in mind and an exemplary object of one aspect of the present invention is to provide a vehicle lamp and control device in which the output current can be stabilized and the current can be limited. Means for solving the problem: One aspect of the present invention relates to a control device that is used with a light source and configures a vehicle lamp. The controller includes a DC / DC converter that receives an input voltage and outputs a control voltage to the light source, and a controller that controls the DC / DC converter. The DC / DC converter comprises: an input terminal, an output terminal and a ground line; a switching transistor and an input induction coil which are arranged in series between the input terminal and the ground line, and an output induction coil. The controller includes: a current controller that compares a first coil current flowing in the output induction coil with a first upper threshold value and a lower one lower threshold value; a current limiter which compares a second coil current flowing in the input induction coil with a second upper threshold value and a second lower threshold value; and a cycle controller which, (i) during a cycle in which the first coil current exceeds the first upper threshold value before the second coil current exceeds the second upper threshold value, (ia) deactivates the transistor of switch-on triggered by the fact that the first coil current exceeds the first upper threshold value, and (ib) activates the triggered switching transistor in that the first coil current becomes lower than the first lower threshold value, and (ii) during a cycle in which the second coil current exceeds the second upper threshold value before the first coil current exceeds the first upper threshold value, (ii-a) deactivates the switching transistor triggered by the the second coil current exceeds the second upper threshold value, and (ii-b) activates the triggered switching transistor in that the second The coil current becomes lower than the second lower threshold value. According to this aspect, just after the first coil current has reached the first upper threshold value and the switching transistor has been deactivated, even if the second coil current decreases to the second lower threshold value, the transistor The switching state of the switching transistor is not immediately activated, but the deactivated state of the switching transistor continues until the first coil current decreases to the first lower threshold value. On the contrary, just after the second coil current has reached the second upper threshold value and the switching transistor has been turned off, even if the first coil current decreases to the first lower threshold value, the transistor The switching state is not immediately activated, but the deactivated state of the switching transistor continues until the second coil current decreases to the second lower threshold value. In this way, it is possible to suppress the increase of the switching frequency. The current controller may include a first hysteresis comparator which compares the first detected voltage which corresponds to the first coil current with the first threshold voltage value which passes through two voltage levels which correspond respectively to the first threshold value. higher and the lower threshold value, and generates a control signal which is enabled when the first detected voltage is lower than the first threshold voltage value. The current limiter may include a second hysteresis comparator which compares the second detected voltage which corresponds to the second coil current with the second threshold voltage value which passes through two voltage levels which correspond respectively to the second threshold value. higher and the second lower threshold value, and generates a limit signal that is enabled while the second detected voltage is less than the second threshold voltage value. The cycle controller may include a logic circuit which generates the pulse signal that is enabled while both the control signal and the limit signal are enabled and which is disabled while at least one of the control and the limit signal are invalidated. According to this configuration, it is possible to appropriately control the switching transistor with a simple configuration. When the output power of the DC / DC converter is equal to For and the input voltage is equal to VIN as a function of the increase of For / VIN, the second upper threshold value and the second lower threshold value can increase. According to this aspect, in the DC / DC converter which stabilizes the output current, it is possible to suppress an oscillation state in which the control state by the current controller and the limit state by the current limiter. current flow frequently and alternately. The current limiter may further include: a first converter VII (voltage / current) which generates a first current which S corresponds to the input voltage VIN; and a second converter VII which generates a second current which corresponds to the output voltage Vou-r of the DC / DC converter. The current limiter can be configured so that the first hysteresis comparator can be shifted according to the first current and the second current. In this case, it is possible to control the priority of the current control and the current limit as a function of the input voltage VIN and the output voltage. The DC / DC converter may further include a capacitor. series which is arranged between the input terminal and the output terminal. The DC / DC converter can be a Cuk converter, a Sepic converter or a Zeta converter. Another aspect of the present invention relates to a vehicle lamp. The vehicle lamp may include: a light source having a plurality of light emitting elements connected in series; the control device as defined above which controls the light source; and at least one bypass switch which is associated with at least one of the plurality of light emitting elements, and is respectively provided in parallel with the corresponding light emitting elements. In this case, a load fluctuation of the DC / DC converter occurs depending on the enabled and disabled states of the bypass switch and the frequency at which the current limit is applied increases. In this case, using the control device described above, both the stable current control and the current limit can be obtained. Advantage of the invention According to one embodiment of the present invention, it is possible to stabilize the output current and apply a current limit. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be well understood and its advantages will be better understood on reading the detailed description which follows. The description refers to the following drawings, which are given by way of example. Figure 1 is a diagram illustrating a vehicle lamp configuration according to the associated technique.
[0003] Fig. 2A is an operating lamp waveform diagram of the vehicle lamp Fig. 2B is an operating lamp waveform diagram of the vehicle lamp Fig. 3 is a block diagram of the vehicle lamp including a control device according to the embodiment. Fig. 4A is an operating waveform diagram of the controller of Fig. 3. Fig. 4B is an operating waveform diagram of the controller of Fig. 3.
[0004] Fig. 5 is a block diagram illustrating an exemplary controller configuration. Fig. 6A is a diagram explaining a current limit value. Fig. 6B is a diagram explaining a current limit value. Fig. 7 is a circuit diagram illustrating an exemplary current limiter configuration. Fig. 8 is a circuit diagram illustrating an exemplary configuration of the vehicle lamp.
[0005] Fig. 9 is a perspective view of a lamp unit (lamp assembly) including the vehicle lamp of Fig. 8. Fig. 10A is a circuit diagram of a Sepic converter and a Zeta converter. Figure 10B is a circuit diagram of a Sepic converter and a Zeta converter. DETAILED DESCRIPTION A preferred embodiment of the present invention will be described hereinafter with reference to the drawings. Elements, organs and processing tasks which are identical or of equivalent configuration will be represented by the same numbers or reference symbols and their description will not be repeated. In addition, the embodiment is only an example and does not limit the invention, and all properties, features and combinations thereof are not necessarily essential to the invention.
[0006] In this description, "a state in which a member A is connected to a member B" comprises the case where the member A and the member B are connected physically and directly and the case where the member A and the member B are connected indirectly via another member, wherein the electrically connected state is not substantially affected or the operation or effect obtained by the link is not changed. Similarly, "a state in which a member C is disposed between the member A and the member B" comprises the case where the member A and the member C or the member B and the member C are connected directly and the case where the member A and the member C or the member B and the member C are indirectly connected via another member, wherein the electrically connected state is not substantially affected or the operation or effect obtained by the link is not changed. In this description, numbers or reference symbols assigned to electrical signals such as a voltage signal, a current signal or the like, or to circuit elements such as a resistor, a capacitor or the like, are assumed respectively represent a voltage value, a current value or a resistance value or a capacitance value, if necessary. FIG. 3 is a block diagram of a vehicle lamp 1 including a controller 20. The controller 20, similar to FIG. 1, is used with a light source 10 to configure the lamp for vehicle 1 as a whole. The controller 20 includes a DC / DC converter 30 and a controller 40. The DC / DC converter 30 receives a VIN input voltage and outputs a Votive control voltage to the light source 10. The controller 40 controls the DC / DC converter 30. The DC / DC converter 30 has an input terminal P1 which receives the input voltage VIN, an output terminal P2 to which is connected the light source 10 which is a load and a power line. GND mass by means of which the light source 10 is connected to ground. The GND ground line connects an input-side ground terminal and an output-side ground terminal. In the present invention, the topology of the DC / DC converter is not particularly limited but a condition of the configuration is to include a switching transistor M1, an input inductor L2 and an inductor L1 output. As a topology to satisfy this condition, an example of a converter Cuk in FIG. 3 is given. The converter Cuk comprises an input capacitor C1, an output capacitor C2, a series capacitor C3 and a rectifying diode D1. in addition to the switching transistor M1, the output induction coil 10 L1 and the input induction coil L2. The input capacitor C1 is disposed between the input terminal P1 and the ground line GND and stabilizes the input voltage VIN. The input inductor L2 and the switching transistor M1 are arranged in series between the input terminal P1 and the ground line GND. The output capacitor C2 is disposed between the output terminal P2 and the GND ground line and stabilizes the output voltage VOUT. The input capacitor C1 and the output capacitor C2 may be omitted. The cathode of the rectifying diode D1 is connected to the ground line GND. One end of the series capacitor C3 is connected to the anode of the rectifying diode D1 and the other end is connected to a connection node N1 of the switching transistor M1 and the input inducing coil L2. One end of the output inductor L1 is connected to the anode of the rectifying diode D1 and the other end is connected to the output terminal P2. The configuration of the DC / DC converter 30 is as described above. The controller 40 will then be described. The controller 40 includes a current controller 42, a current limiter 44, a cycle controller 46 and an amplifier 48.
[0007] The current controller 42 is provided to stabilize the first coil current In flowing in the output induction coil L1 in the target range according to the target luminance of the light source 10. Specifically, the current controller 42 compares the first coil current In flowing in the output induction coil L1 with a first upper threshold value IREFFi and a first lower threshold value IREFL and generates a control signal S1 which indicates the result of the comparison. The current limiter 44 is provided to limit the current so that the second coil current IL2 flowing in the input inductor L2 does not exceed a current limit value IPEAK which is determined from the point of view of the current. reliability of the circuit. The current limit value IPEAK is set to a value greater than that of a second coil current IL2_NORm in the normal state and lower than that of a maximum rated current MAX of the elements on the path traveled by the second coil current 1E2. The current limiter 44 compares the second coil current IL2 flowing in the input inductor L2 with a second upper threshold value IPEAKH and a second lower threshold value IPEAKL, and generates a limit signal S2 which indicates the result of the comparison. The current sensing method of the current controller 42 and the current limiter 44 is not particularly limited, but in the present embodiment, for detecting a current flowing in the output induction coil L1 (first current In) and a current flowing in the input inductor L2 (second coil current IL2, a first sensing resistor Ri and a second sensing resistor R2 are provided in the coil current path l In the first detection resistor R1 and the second detection resistor R2, voltage drops occur (sensed voltages) VR1 and VR2 which are proportional to the coil currents IL1 and IL2 which are the subject of the detection. The current controller 42 compares the first detected voltage VR1 with the voltage threshold values VREFH and VREFL corresponding to IREFH and IREFL. Current counter 44 compares the second detected voltage VR2 with the voltage threshold values VPEAKH and VPEAKL corresponding to IPEAKH and IPEAKL- (i) During a cycle in which the first coil current In exceeds the first upper threshold value IREFH before the second coil current IL2 exceeds the second upper threshold value IPEAKH, (ia) the cycle controller 46 deactivates the switching transistor M1 triggered by the fact that the first coil current In exceeds the first threshold value higher than IREFH and (ib) activates the switching transistor M1 triggered by the fact that the first coil current In decreases below the first lower threshold value IREFL- In addition, (ii) during a cycle in which the second read coil current exceeds the second upper threshold value IpEAKFi before the first coil current In exceeds the first upper threshold value IREFH, ( ii-a) the cycle controller 46 deactivates the switching transistor M1 triggered by the fact that the second coil current 42 exceeds the second upper threshold value IPEAKI-1, and (ii-b) activates the switching transistor M1 triggered in that the second coil current 11.2 decreases below the second lower threshold value IPEAKL- The cycle controller 46 outputs a pulse signal S3 which controls the activation and deactivation of the switching transistor M1. Amplifier 48 switches switching transistor M1 based on pulse signal S3. The configuration of the controller 20 is as described above. The operation of the controller 20 will then be described. Figs. 4A and 4B are operating waveform diagrams of the controller 20 of Fig. 3. Referring to Fig. 4A, focusing on a certain cycle Ts, the switching transistor M1 is activated. at an initial state and the coil currents ILi and IL2 increase. At time t0, In reaches IREFH before IL2 reaches IPEaKH- Accordingly, at time t0, switching transistor M1 is turned off. When the switching transistor M1 is turned off, the coil currents In and IL2 begin to decrease. At time ti, Ill decreases to IPEAKL, then, at time t2, In decreases to IREFL- In this case, switching transistor M1 is activated at time t2 (solid line) and not at time tl (dashed line). That is, in Fig. 4A, the output current λ1 is stabilized in the target range by the current controller 42 (current control). Referring to Fig. 4B, focusing on a certain cycle T5, the switching transistor M1 is turned on in an initial state and the coil currents In and IL2 increase. At the instant tO, IL2 reaches IpEAKH before ILI. reaches IREFH. As a result, at time t0, switching transistor M1 is turned off. When the switching transistor M1 is deactivated the coil currents IL1. and Ill start to decrease. At time t1, In decreases to IREFL and at time t2, 1 [2 then decreases to IPEAKL. In this case, the transistor M1 is activated at time t2 (solid line), and not at time t1 (dashed line). That is, in FIG. 4B, the ILI input current. is limited by the current limiter 44.
[0008] The operation of the controller 20 is as described above. According to the control device 20 of FIG. 3, just after the first coil current In has reached the first threshold value IREFH and the switching transistor M1 has been deactivated, even if the second coil current IL2 decreases to at the second lower threshold value IPEAKL, the switching transistor M1 is not immediately activated, but the deactivated state of the switching transistor M1 continues until the first coil current IL1 decreases to the first IREFL lower threshold value. On the contrary, just after the second coil current IL2 has reached the second upper threshold value IPEAKH and the switching transistor M1 has been deactivated, even if the first coil current In decreases to the first lower threshold value. IREFL, the switching transistor M1 is not directly activated, but the deactivated state of the switching transistor M1 continues until the second coil current IL2 decreases to the second lower threshold value IPEAKL. With this control, it is possible to suppress the increase of the switching frequency. A specific example of the controller 20 will then be described. FIG. 5 is a block diagram illustrating an example configuration of the controller 40. The current controller 42 comprises a first hysteresis comparator 50. The first hysteresis comparator 50 compares the first detected voltage VR1 which corresponds to the first current of coil In with the first threshold voltage value WEIL and valid (for example at high level) the control signal 51 while the first detected voltage VRL is lower than the first threshold voltage value VTFIL. Using the hysteresis comparator, the first threshold voltage value VTHL passes through two voltage levels, VTFI1H and VTH1L, respectively corresponding to the first upper threshold value IREFH and the first lower threshold value IREFL and the transition is in accordance with the control signal S1 which is the output of the first hysteresis comparator 50. In addition, the current limiter 44 has a second hysteresis comparator 52. The second comparator hysteresis 52 compares the second detected voltage VR2 which corresponds to the second coil current 1E2 with the second threshold voltage value VTH2, and validates (for example, high) the limit signal S2 while the second detected voltage VR2 is less than the second threshold voltage value VTH2. Using the hysteresis comparator, the second threshold voltage value VTH2 passes through two voltage levels VTH2H and VTH2L, which correspond respectively to the second upper threshold value IPEAKH and the second lower threshold value IPEAKL, and the transition is effected in accordance with the limit signal S2 which is the output of the second hysteresis comparator 52. The cycle controller 46 has a logic circuit 54. The logic circuit 54 generates the pulse signal S3 based on the signal 15. control S1 and on the limit signal S2. The logic circuit 54 validates (at the high level) the pulse signal S3 while the control signal S1 and the limit signal S2 are validated (at the high level) and deactivates the pulse signal S3 while at least one signal among the signal control S1 and the limit signal S2 is disabled. For example, logic circuit 54 is an AND gate. Those skilled in the art can understand that the logic circuit 54 having the same function can be realized by also using an inverter, an OR gate, a NOR gate, an EXCLUSIVE gate OR other logic gates. According to the controller 40 of FIG. 5, it is possible to suitably control the switching transistor M1. An upper limit value of the current limiting by the current limiter 44 will then be described. In the foregoing description, the current limit value IpEAK is constant. However, it is preferable that these values vary depending on the state of the controller 20. Figs. 6A and 6B are diagrams explaining the current limit value IPEAK. In the normal state, the second coil current ILL_NORm flowing in the input inductor L2 can approach IL2_, NORM = POLIT / VIN. As illustrated in FIG. 6A, in the case where the current limit value is constant, while the POLIT / VIN decreases, the difference ΔI between the current limit value IpEAK and the second current of the current. IL2_NORM coil at normal time increases. In the case where AI is large, when the current control state migrates to the state of current limit due to the variations of the source voltage and the load, the value of the variation of the second coil current 1L2 increases. As the value of the variation increases, it becomes easy to enter the state of oscillation by repeating the current control state and the current limit state, and the degree of oscillation also increases. To solve this problem, as illustrated by the dashed lines (i) and (ii) in Figure 6B, it is preferable to dynamically change the current limit value IPEAK. Specifically, it is preferable to increase the current limit value IPEAK as a function of the second coil current Ill_NORM at the normal time which increases, in other words, depending on the increase of Pour / VIN. In this way, with respect to the case of FIG. 6A, the difference AI between the current limit value IPEAK and the second coil current Ii_2NiOrm at the normal time can be decreased, and it is possible to improve the resistance to oscillation. FIG. 7 is a circuit diagram illustrating an exemplary configuration of the current limiter 44. Assuming that the output current I or T is constant, the output power For is proportional to the output voltage. As a result, the current limiter 44 causes the IPEAK current limit value to increase as a function of the increase in the output voltage. In addition, the current limiter 44 causes the IPEAK current limit value to increase as a function of the 1 / VIN increase, in other words, as a function of the VIN decrease. The current limiter 44 includes a first converter VII and a second converter VII in addition to the second hysteresis comparator 52. The second hysteresis comparator 52 compares the detected voltage VR2 with a voltage threshold value VTH. In this example, VR2 is a negative voltage. By comparing VTH '+ VR2 with 0 volts, the voltage comparator 70 compares VTH' with the absolute value of VR2. Resistors 21 and 22 are provided for the addition of voltage (averaging). A transistor M21 and a resistor R23 are provided to set the hysteresis to the threshold voltage value VTH '. The transistor M21 is in the activated state when the output of the voltage comparator 70 is high and is in the off state when the output of the voltage comparator 70 is low. When the transistor M21 is in the deactivated state, VTH 'is equal to VTH and when the transistor M21 is in the activated state, VTH' is equal to VTH x R23 / (R23 + R24) and passes to the threshold value lower. The configuration of the second hysteresis comparator 52 is not limited to that of FIG. 7 and a well-known hysteresis comparator can be used. The first V / I converter 60 generates a first current I1 which corresponds to the input voltage VIN. The second converter VII 62 generates a second current 12 which corresponds to the output voltage Vou-r of the DC / DC converter. For example, the first converter VII 60 and the second converter VII 62 can be configured using a current mirror circuit. The first current fi increases as the input voltage VIN increases. The second current 12 increases when the output voltage VouT decreases (when the absolute value of VouT increases). The current limiter 44 is configured so that the first hysteresis comparator 50 can be shifted according to the first current fi and the second current 12. The first converter VII 60 and the second converter V / I 62 deliver the current appropriate node N2 in the second hysteresis comparator 52 or extract the current from the node. In this way, the voltage threshold value VTH 'is shifted according to the input voltage VIN and the output voltage VOUT. Specifically, as the output voltage V0'r increases, the voltage threshold value VTH 'increases and as the input voltage VIN decreases, the voltage threshold value VTH' increases. In this way, as illustrated in FIG. 6B, it is possible to modify the current limit value IpEAK as a function of PouT / VIN. The node N2 which activates the current and the current 12 is not limited to that of FIG. 7 and its position is not limited insofar as the node can provide the offset to the second hysteresis comparator 52. the bias current in a voltage comparator 70 can be varied according to the current and the current 12.
[0009] An example of a specific configuration of the vehicle lamp 1 will then be described. Fig. 8 is a circuit diagram illustrating the exemplary configuration of the vehicle lamp 1. The light source 10 has a plurality (number N) of light emitting elements 12 connected in series. The light emitting element 12 is for example an LED (light-emitting diode). The DC / DC converter 30 delivers a control voltage Vota between the anode and the cathode of the light source 10. An output induction coil L3 constitutes a filter 32 with the output capacitor C2 of the DC / DC converter 30 With the filter 32, the current Iour flowing in the light source 10 is smoothed.
[0010] The controller 20 includes a plurality of branch switches SW1 to SWN in addition to the DC / DC converter 30 and the controller 40. The plurality of branch switches SW1 to SWN are associated with the plurality of light emitting elements 12_1 through 12_N and are respectively provided in parallel with corresponding light emitting elements. The output current away from the DC / DC converter 30 is stabilized at the target value by means of the DC / DC converter 30 and the controller 40. In a state in which all the branch switches SW1 to SWN are in the OFF state, the output current 'oui enters all the light emitting elements 12 and the luminance is brought to the maximum. When any of the bypass switches SW i is turned off, the output current u does not enter the light emitting elements 12 i but enters the switch side SW i and the light emitting elements 12 i are turned off. The controller 40 controls the luminance or light distribution of the vehicle lamp assembly 1 by controlling the on and off states of the plurality of branch switches SW1 to SWN. In the vehicle lamp 1 of Fig. 8, a load fluctuation of the DC / DC converter 30 occurs as a function of the on and off states of the branch switches SW1 to SWN, and the frequency at which the current limit is applied increases. . In this case, using the control device 20 described above, both the stable current control and the current limit can be obtained. Finally, a use of the vehicle lamp 1 will be described. Fig. 9 is a perspective view of a lamp unit (lamp assembly) 500 including the vehicle lamp 1 of Fig. 8. The lamp unit 500 comprises a transparent cover 502, a high beam unit 504, a dipped beam unit 506 and a housing 508. The vehicle lamp 1 described above may be used for example for the high beam unit 504. Each of a plurality of light emitting elements 12 is for example arranged in the lateral direction in a row so as to illuminate different areas. In the state where the vehicle is moving, the areas to be illuminated are then adaptively selected by the vehicle-side controller, for example, by the electronic control unit (ECU). In the vehicle lamp 1, the data for requesting the area to be illuminated is inputted, and the vehicle lamp 1 turns on the light source 10 (light emitting elements 12) in a manner corresponding to the requested area. As described above, the present invention is described with the embodiment. The present embodiment is an example and various examples of modifications can be made to the combinations of each configuration element and each processing process. In addition, those skilled in the art will appreciate that these modification examples are also within the scope of the present invention.
[0011] The modification example will be described below. (Example of modification 1) In the embodiment, the case where the Cuk converter is used as a DC / DC converter is described, but the present invention is not limited thereto. The DC / DC converter 30 must have a topology including the output inductor L1, the input inductor L2 and the switching transistor M1. From this point of view, it is possible to use a Sepic converter or a Zeta converter. Figs. 10A and 10B are circuit diagrams of the Sepic converter and the Zeta converter. The Sepic converter of Fig. 10A has a configuration in which the positions of the rectifying diode D1 and the output induction coil L1 in the converter CUK are permuted. The Zeta converter of Fig. 10B has a configuration in which the positions of the switching transistor M1 and the input inductor L2 in the converter Cuk are swapped and the direction of the rectifying diode D1 is reversed.
[0012] The converters Cuk, Sepic and Zeta are identical insofar as the series capacitor C3 is arranged between an input terminal P1 and an output terminal P2 and the oscillation easily occurs due to the series capacitor C3 with respect to converters having another topology. To control the converters, it is very useful to combine the controller 40 which has excellent stability. (Modification example 2) The method for detecting the coil currents In and IL2 is not limited to the method of the embodiment. For example, the detection resistors R1 and R2 may be inserted in another position. Alternatively, instead of the resistors, the impedance of the known transistors can be used. (Example of modification 3) In the vehicle lamp 1 of FIG. 8, the case where the plurality of branch switches SW1 to SWN are associated with all of the light emitting elements 12_1 to 12_N is described, but the present embodiment is not limited thereto. For example, without provision for bypass switches SW, light emitting elements 12 may exist, constantly illuminating or a series circuit having a plurality of light emitting elements may be connected in parallel with a branch switch SW. (Example of modification 4) A laser diode (DL) different from the LED can be used as the light source 10. (Example of modification 5) In the lamp unit 500 of FIG. 9, the case where the Vehicle lamp 1 of Figure 3 is used for high beam unit 504 is described. However, alternatively or additionally, the vehicle lamp 1 may be used for the dipped beam unit 506.
[0013] The present invention is described using specific terms based on the embodiment. However, the embodiment presented is merely an example of the principles or applications of the invention. Various modification examples or alternative arrangements may be acceptable within the scope and spirit of the present invention.

权利要求:
Claims (7)
[0001]
REVENDICATIONS1. A control device (20) which is used with a light source and configures a vehicle lamp, the device comprising: a DC / DC converter (30) which receives an input voltage VIN and delivers a control voltage Votive to the light source ; and a controller (40) which controls the DC / DC converter (30), wherein the DC / DC converter (30) comprises: an input terminal (P1), an output terminal (P2) and a line of 10 mass (GND); a switching transistor (M1) and an input induction coil (L2) which are arranged in series between the input terminal (P1) and the ground line (GND), and an output induction coil (L1), and wherein the controller (40) comprises: a current controller (42) which compares a first coil current flowing in the output induction coil (11) with a first upper threshold value IREFH and a first lower threshold value IREFL 20 a current limiter (44) which compares a second coil current IL2 flowing in the input inductor (L2) with a second upper threshold value IPEAKH and a second threshold value lower IPEAKL; and a cycle controller (46) which, (i) during a cycle in which the first coil current IL1 exceeds the first upper threshold value IREFH before the second coil current 1L2 exceeds the second upper threshold value IPEAKH (ia) deactivates the switching transistor (M1) triggered by the fact that the first coil current ILi exceeds the first upper threshold value IREFH, and (ib) activates the switching transistor (M1) triggered by the fact that the first coil current ILi becomes lower than the first lower threshold value IREFL / and (ii) during a cycle in which the second coil current 1L2 exceeds the second upper threshold value IPEAKH before the first coil current IL1 exceeds the first upper threshold value IREFH, (ii-a) deactivates the switching transistor (M1) triggered by the fact that the second coil current IL2 exceeds the second value. r upper threshold IPEAKH, and (ii-b) activates the switching transistor (M1) triggered by the fact that the second coil current 1L2 becomes lower than the second lower threshold value IPEAKL. 5
[0002]
The control device (20) according to claim 1, wherein the current controller (42) includes a first hysteresis comparator (50) which compares the first detected voltage VR1 which corresponds to the first coil current In with the first threshold voltage value VTH1 which passes through two voltage levels corresponding respectively to the first upper threshold value IREFH and the first lower threshold value IREFLI and generates a control signal which is validated when the first detected voltage VR1 is lower at the first threshold voltage value V-1-Hi, wherein the current limiter (44) comprises a second hysteresis comparator (52) which compares the second detected voltage VR2 which corresponds to the second coil current read with the second threshold voltage value V-ni2 which passes through two voltage levels corresponding respectively to the second upper threshold value IPEAKH and the second second lower threshold value IPEAKL, and generates a limit signal S2 which is enabled while the second detected voltage VR2 is less than the second threshold voltage value V-Ri2, and wherein the cycle controller (46) has a logic circuit (54) which generates the pulse signal which is enabled while both the control signal S1 and the limit signal S2 are enabled and which is disabled while at least one of the control signal S1 and the limit signal S2 are disabled.
[0003]
The control device (20) according to claim 1 or 2, wherein, when the output power of the DC / DC converter (30) is equal to For and the input voltage is equal to VIN as a function of the increase in Pour / VIN, the second upper threshold value IPEAKH and the second lower threshold value IPEAKL increase.
[0004]
The control device (20) according to claim 2, wherein the current limiter (44) further comprises: a first converter (voltage / current) which generates a first current which corresponds to the input voltage VIN; and a second V / I converter which generates a second current which corresponds to the output voltage of the DC / DC converter (30), and in which the current limiter (44) is configured so that the first comparator hysteresis (50) can be shifted according to the first current and the second current.
[0005]
The control device (20) according to any one of claims 1 to 4, wherein the DC / DC converter (30) further comprises a series capacitor (C3) which is disposed between the input terminal (P1). ) and the output terminal (P2). 15
[0006]
A vehicle lamp (1) comprising: a light source (10) having a plurality of light emitting elements connected in series; the control device (20) according to any one of claims 1 to 5 which controls the light source (10); and at least one branch switch (SW) which is associated with at least one of the plurality of light emitting elements, and is respectively provided in parallel with the corresponding light emitting elements. 25
[0007]
A method of controlling a vehicle lamp (1) including a light source (10) and a DC / DC converter (30) which receives a VIN input voltage and outputs a control voltage Vour to the source of light (10), wherein the DC / DC converter (30) comprises: an input terminal (P1), an output terminal (P2) and a ground line (GND); a switching transistor (M1) and an input induction coil (L2) which are arranged in series between the input terminal (P1) and the ground line (GND), and an output induction coil (L1) provided between the input terminal (P1) and the output terminal (P2), andwherein the control method comprises the steps of. comparing a first coil current In flowing in the output induction coil (L1) with a first upper threshold value IREFH and a first lower threshold value IREFL; comparing a second coil current IL2 flowing in the input inductor (L2) with a second upper threshold value IpEAKH and a second lower threshold value IPEAKL; (i) during a cycle in which the first coil current Iii exceeds the first upper threshold value IREFH before the second coil current IL2 exceeds the second upper threshold value IpEAKii, (ia) disable the switching transistor (M1 ) triggered by the fact that the first coil current ILi exceeds the first upper threshold value IREFH, and (ib) activate the switching transistor (M1) triggered by the fact that the first coil current ILi becomes smaller than the first value lower threshold IREFL, and (ii) during a cycle in which the second coil current 11.2 exceeds the second upper threshold value IPEAKH before the first coil current In exceeds the first upper threshold value IREFH, (ii-a ) deactivating the switching transistor (M1) triggered by the fact that the second coil current (IL2) exceeds the second upper threshold value IPEAKFI, and (ii-b) enabling the tran switching sistor (M1) triggered by the fact that the second coil current (IL2) becomes lower than the second lower threshold value IPEAKL-25

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CN104837237B|2017-07-14|

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CN104837237A|2015-08-12|

JP2015153526A|2015-08-24|

DE102015202410A1|2015-09-17|

US20150230302A1|2015-08-13|

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JP6262557B2|2018-01-17|

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优先权:

申请号 | 申请日 | 专利标题

JP2014024759A|JP6262557B2|2014-02-12|2014-02-12|VEHICLE LAMP, ITS DRIVE DEVICE, AND CONTROL METHOD THEREOF|

JP2014024759|2014-02-12|

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