JP2011113763A - On-board lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an on-board lighting device reducing the frequency of the light-out due to reduction in input voltage. <P>SOLUTION: It is determined whether or not to charge a battery based on an AC component included in an input voltage Vin from the battery. When it is determined that the battery has charge, power output to an electric light source is stopped immediately when the voltage from the battery falls below a first minimum voltage Vb1. When it is determined that the battery does not have charge, however, power output to the electric light source is not stopped unless a duration time T1v where the input voltage Vin is lower than a second minimum voltage Vb2 lower than the first minimum voltage Vb1 continues for a predetermined drop determination time Tsh. Reduction in input voltage Vin is less likely to turn off the electric light source as compared to a case of always performing the operation to be performed when it is determined that the battery has the charge. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an in-vehicle lighting device.

  2. Description of the Related Art Conventionally, an in-vehicle lighting device that lights an electric light source using a battery (that is, a secondary battery) mounted on an automobile as a power source has been provided.

  The battery is charged by a generator linked to the drive system of the automobile while the engine is operating or when the regenerative brake is used.

  By the way, since the battery is also used as a power source for a cell motor or the like for starting the engine, there is a possibility that the engine cannot be started when the battery is excessively consumed.

  Therefore, when the discharge power is higher than the charge power in the above battery, the discharge power is reduced by stopping the power supply in order from the load with the predetermined low priority among the loads using the battery as a power source. Thus, a technique has been proposed that balances the charging power and keeps the voltage of the battery constant (see, for example, Patent Document 1).

  Further, in an in-vehicle lighting device that turns on an electric light source using the battery as a power source, an operation for preventing excessive consumption of the battery is an input voltage from the battery (hereinafter simply referred to as “input voltage”). .) Is monitored, and the electric light source is turned off when the input voltage falls below a predetermined lower limit voltage.

Japanese Patent No. 3624831 (paragraph numbers 0140 to 0144)

  However, as described above, when the electric light source is turned off when the input voltage falls below the lower limit voltage, due to a temporary decrease in the input voltage due to power consumption by the cell motor or the like at the start of the engine, Electric light source is likely to turn off.

  In recent years, from the viewpoint of saving fuel and reducing carbon dioxide emissions, it is recommended to stop the engine even during a temporary stop such as waiting for a signal (so-called idling stop). An idling stop device that detects and automatically stops the engine is also provided. And when practicing such an idling stop, the frequency with which such a light extinction occurs is increased.

  Since the light extinction due to the decrease in the input voltage is not intended by the user, the frequency is desirably low.

  The present invention has been made in view of the above reasons, and an object thereof is to provide an in-vehicle lighting device in which the frequency of turning off due to a decrease in input voltage is reduced.

  The invention of claim 1 is an in-vehicle lighting device that turns on an electrical light source using a battery mounted in an automobile and charged by a charging current including an AC component as a power source, and converts electric power input from the battery. A power conversion unit that turns on the electrical light source by outputting to the electrical light source, an input voltage detection unit that detects an input voltage from the battery to the power conversion unit, and an alternating current included in the input voltage from the battery to the power conversion unit A ripple detection unit that generates an output according to the component, and determines whether or not the battery is charged based on the output of the ripple detection unit, and the input voltage detected by the input voltage detection unit and the determination result of the presence or absence of charging And a control unit that controls the power conversion unit according to the control unit.The control unit is detected by the input voltage detection unit in a state where it is determined that the battery is charged. When the input voltage falls below a predetermined first lower limit voltage, and when the input voltage detected by the input voltage detection unit is lower than the first lower limit voltage when it is determined that the battery is not charged. (2) When the state where the voltage is lower than the lower limit voltage continues for a predetermined decrease determination time or longer, output of power from the power conversion unit to the electrical light source is stopped.

  According to the present invention, the frequency of turn-off is reduced compared to the case where the output of power from the power converter is stopped when the input voltage falls below the first lower limit voltage regardless of whether or not the battery is charged.

  According to a second aspect of the present invention, in the first aspect of the invention, the control unit calculates an input decrease rate, which is a decrease per unit time of the input voltage detected by the input voltage detection unit, as needed, and charges the battery. When the input decrease rate is equal to or higher than the predetermined determination decrease rate in a state where it is determined that there is no noise, the input voltage detected by the input voltage detection unit is compared with a predetermined third lower limit voltage lower than the second lower limit voltage. The output of power from the power conversion unit to the electrical light source is stopped without waiting for the elapse of the decrease determination time when the input voltage is less than the third lower limit voltage. In-vehicle lighting device.

  According to this invention, compared with the case where the output of power is not stopped when the input voltage becomes less than the third lower limit voltage, the continuation of the operation in a state where the input voltage is reduced is suppressed.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, a filter unit that suppresses input of noise from the power conversion unit to the ripple detection unit is provided.

  According to the present invention, erroneous determination caused by noise generated by the power conversion unit can be suppressed as compared with the case where no filter unit is provided.

  According to a fourth aspect of the present invention, in the first to third aspects of the invention, the electrical light source connected to the power conversion unit is a discharge lamp, and the control unit is a unit time of the input voltage detected by the input voltage detection unit. The power conversion unit calculates the input decrease rate, which is the per unit decrease rate, as needed, and the power conversion unit for a predetermined time from when the input decrease rate exceeds the predetermined determination decrease rate in a state where it is determined that the battery is not charged. The output power is temporarily increased.

  According to this invention, compared with the case where the operation | movement which increases the output power of a power converter part temporarily is not performed, the extinction of the discharge lamp connected to the power converter part is suppressed.

  According to a fifth aspect of the present invention, in the first to fourth aspects of the invention, the power conversion unit outputs AC power to a high-pressure discharge lamp as an electric light source, and the control unit is detected by the input voltage detection unit. From time to time, the input reduction rate, which is the rate of reduction of the input voltage per unit time, is calculated as needed, and when the input reduction rate exceeds the predetermined determination reduction rate in a state where it is determined that the battery is not charged. The output frequency of the power conversion unit is lowered for a predetermined time.

  According to the present invention, the number of zero-cross points per unit time is reduced in the output voltage of the power conversion unit, so that the high-pressure discharge lamp connected to the power conversion unit can be prevented from disappearing.

  According to a sixth aspect of the present invention, in the first to fifth aspects of the present invention, the power conversion unit includes a noise source that periodically generates noise, and the control unit performs ripple during a period in which noise is generated by the noise source. Regardless of the output of the detector, it is determined that the battery is charged.

  According to the present invention, although the battery is actually charged, it is determined that the battery is not charged due to the noise of the noise source, and the inefficient operation in the state where the battery voltage is lowered is continued. Can be avoided.

  According to the first aspect of the present invention, the control unit is configured such that when the input voltage detected by the input voltage detection unit falls below a predetermined first lower limit voltage in a state where it is determined that the battery is charged, and When it is determined that the battery is not charged and the state where the input voltage detected by the input voltage detection unit falls below a predetermined second lower limit voltage lower than the first lower limit voltage continues for a predetermined decrease determination time or longer. In addition, since the output of power from the power converter to the electrical light source is stopped, the output of power from the power converter when the input voltage falls below the first lower limit voltage regardless of whether the battery is charged or not. The frequency of turn-off is lower than when the is stopped.

  According to the second aspect of the present invention, the control unit calculates the input decrease rate, which is the decrease rate per unit time of the input voltage detected by the input voltage detection unit, and determines that the battery is not charged. The input voltage detected by the input voltage detection unit is compared with a predetermined third lower limit voltage lower than the second lower limit voltage, and the input voltage Is less than the third lower limit voltage, the output of power from the power conversion unit to the electrical light source is stopped without waiting for the elapse of the decrease determination time, so that when the input voltage becomes less than the third lower limit voltage Compared with the case where the output of power is not stopped, the continuation of operation in a state where the input voltage is reduced is suppressed.

  According to the invention of claim 3, since the filter unit that suppresses the input of noise from the power conversion unit to the ripple detection unit is provided, the erroneous determination caused by the noise generated by the power conversion unit compared to the case where the filter unit is not provided. Is suppressed.

  According to the invention of claim 4, the electric light source connected to the power conversion unit is a discharge lamp, and the control unit is an input that is a decrease width per unit time of the input voltage detected by the input voltage detection unit. While calculating the reduction rate as needed, the output power of the power converter is temporarily changed for a predetermined time from when the input reduction rate becomes equal to or higher than the predetermined determination reduction rate in a state where it is determined that the battery is not charged. Since it increases, compared with the case where the operation | movement which increases the output power of a power converter part temporarily is not performed, the extinction of the discharge lamp connected to the power converter part is suppressed.

  According to the invention of claim 5, the power conversion unit outputs AC power to the high-pressure discharge lamp as an electric light source, and the control unit is a unit time of the input voltage detected by the input voltage detection unit. The power conversion unit calculates the input decrease rate, which is the per unit decrease rate, as needed, and the power conversion unit for a predetermined time from when the input decrease rate exceeds the predetermined determination decrease rate in a state where it is determined that the battery is not charged. Since the number of zero cross points per unit time in the output voltage of the power converter decreases, the extinction of the high-pressure discharge lamp connected to the power converter can be suppressed.

  According to the sixth aspect of the present invention, the power conversion unit includes a noise source that periodically generates noise, and the control unit is independent of the output of the ripple detection unit during a period in which noise is generated by the noise source. Since it is determined that the battery is charged, the efficiency when the battery voltage is reduced due to the fact that the battery is charged but the battery is not charged due to noise from the noise source. It can be avoided that the bad operation continues.

It is a flowchart which shows the operation | movement of the monitoring of the power supply voltage performed during steady operation in embodiment of this invention. It is a circuit block diagram which shows the same as the above. It is a circuit block diagram which shows the ripple detection part in the same as the above. It is explanatory drawing which shows an example of the time change of the input differential voltage in the same as the above, a clock voltage, and a ripple detection voltage. It is a flowchart which shows the starting operation | movement in the same as the above. It is a flowchart which shows the operation | movement of the output voltage monitoring performed during a steady operation in the same as the above. It is a flowchart which shows the operation | movement of the monitoring of the power supply voltage performed during a steady operation in the example of a change same as the above. It is a circuit block diagram which shows another example of a change same as the above. It is explanatory drawing which shows an example of the time change of the output voltage of an inverter, and a mask voltage in another modification example same as the above.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  As shown in FIG. 2, the present embodiment is connected to a battery E mounted on an automobile (not shown) and a high-pressure discharge lamp DL as an electric light source, and the high-pressure discharge lamp DL is turned on using the battery E as a power source. It is something to be made.

  More specifically, in the present embodiment, a DC voltage (hereinafter referred to as “output voltage”) obtained by converting a voltage value of a DC voltage (hereinafter referred to as “input voltage”) Vin input from the battery E via the filter unit 10. The DC-DC converter 11 that outputs Vdc and the common-mode choke coil CC are connected to the high-pressure discharge lamp DL, and the output of the DC-DC converter 11 is converted into AC power and output to the high-pressure discharge lamp DL. Thus, the inverter 12 that turns on the high-pressure discharge lamp DL and the control unit 2 that controls the DC-DC converter 11 and the inverter 12 are provided. That is, the DC-DC converter 11 and the inverter 12 constitute a power converter in the claims.

  The filter unit 10 includes a normal mode choke (inductor) connected between the output terminal on the high voltage side of the battery E and the DC-DC converter 11, and one end connected to one end of the normal mode choke. The LC low-pass filter is composed of two across-the-line capacitors whose ends are connected to the ground.

  The DC-DC converter 11 includes a transformer T0 having a primary winding with an input voltage Vin input to one end thereof, and a switching element Q0 composed of an NMOS connected between the other end of the primary winding of the transformer T0 and the ground. A diode D0 having a cathode connected to one end of the secondary winding of the transformer T0, an output capacitor having one end connected to the anode of the diode D0 and the other end connected to the ground together with the other end of the secondary winding of the transformer T0 This is a known flyback converter that includes C0 and a first drive circuit 11a that drives the switching element Q0 on and off, and uses the voltage Vdc across the output capacitor C0 as an output voltage. That is, when the first drive circuit 11a periodically drives the switching element Q0 on and off, the input voltage Vin from the battery E is converted to an output voltage Vdc corresponding to the on-duty of the switching element Q0 and output.

  The first drive circuit 11a includes a switching current detection unit CD that outputs a higher voltage as the current flowing through the switching element Q0 of the DC-DC converter 1 (hereinafter referred to as “switching current”) increases, and the switching current detection unit CD. Is output to the non-inverting input terminal, the comparator CP1 to which the control voltage Vop is input from the control unit 2 is input to the inverting input terminal, and the output voltage of the comparator CP1 is input to the reset terminal R and the set terminal S. 1 includes an RS-type flip-flop circuit FF to which a set voltage Vs is input from the control unit 2, one input terminal connected to the output terminal Q of the flip-flop circuit FF, and the other input terminal connected to the set voltage from the control unit 2. AND circuit AN having Vs input and an output terminal connected to the gate of switching element Q0 Provided with a door. The set voltage Vs is periodically switched at a predetermined frequency between the H level and the L level. That is, the switching element Q0 is turned on when the set voltage Vs becomes H level. After the switching element Q0 is turned on, the switching current gradually increases, and the current value of the switching current is a predetermined value corresponding to the control voltage Vop. The switching element Q0 is turned off when the input to the reset terminal R of the flip-flop circuit FF reaches the H level when the value is reached, and the switching element Q0 is kept off until the set voltage Vs becomes the H level next time. Is done. That is, the higher the control voltage Vop, the larger the on-duty of the switching element Q0.

  The inverter 12 includes two sets of series circuits of two switching elements Q1 to Q4, a full bridge circuit in which the output terminals of the DC-DC converter 11 are connected in parallel to each other, and the switching elements Q1 to Q4 being driven on and off. And a second drive circuit 12a. The full-bridge inverter is a known full-bridge inverter having an output terminal as a connection point of the switching elements Q1 to Q4 of each series circuit of the full-bridge circuit. That is, the switching elements Q1 to Q4 positioned diagonally to each other are simultaneously turned on, and at least one of the switching elements Q1 to Q4 connected in series to each other is turned off. By periodically turning on and off the elements Q1 to Q4, the output voltage Vd of the DC-DC converter 11 is converted into a rectangular wave AC voltage and output. Here, in order to prevent the output terminals of the DC-DC converter 11 from being short-circuited, a period in which one set of each of the switching elements Q1, Q4 that are diagonally located and turned on at the same time is turned on, A period (dead time) in which all the switching elements Q1 to Q4 of the inverter 12 are turned off is provided between the period when the other switching elements Q2 and Q3 are turned on. The second drive circuit 12a has, for example, two input terminals that are associated with two of the switching elements Q1 to Q4 of the inverter 12 that are located diagonally to each other and connected to the control unit 2, respectively. During the period when the input voltage to any one of the input terminals is at the H level, the two switching elements Q1 to Q4 associated with the input terminal are turned on. In this case, the on / off frequency of each of the switching elements Q1 to Q4 (that is, the frequency of the power output to the high-pressure discharge lamp DL, hereinafter referred to as “operation frequency”) is the input voltage to each of the input terminals. Match the frequency. The second driving circuit 12a as described above can be realized by a well-known technique, and a general-purpose driver IC (for example, IR2111 manufactured by International Rectifier Co., Ltd. or UBA2032TS manufactured by Philips Co., Ltd.) may be used. Detailed illustration and description are omitted.

  Moreover, this embodiment is provided with the starting part 13 and the starting power supply part 14 which produces | generates the power supply of the starting part 13 as a circuit which generates the high voltage pulse for starting of the high pressure discharge lamp DL.

  The starting power supply unit 14 is connected to the connection point between the secondary winding of the transformer T0 of the DC-DC converter 11 and the diode D0 and the starting unit 13 via resistors, and includes four resistors and four diodes. This is a well-known Cockcroft-Walton circuit, which rectifies and boosts the voltage induced in the secondary winding of the transformer T0 of the DC-DC converter 11 and inputs it to the starter 13.

  The starter 13 is a series of a transformer T1 in which a secondary winding is inserted in a conductive path from the inverter 12 to the high-pressure discharge lamp DL, a spark gap SG connected between both ends of the primary winding of the transformer, and a capacitor C1. The connection point between the primary winding of the transformer T1 and the spark gap SG is connected to the starting power supply unit 14, and the connection point between the spark gap SG and the capacitor C1 is connected to the ground. That is, immediately after the power is turned on, the capacitor C1 of the starter 13 is charged by the output of the starter power supply 14. When the voltage across the capacitor C1 rises sufficiently and dielectric breakdown occurs in the spark gap SG, an induced voltage is generated in the secondary winding due to the discharge current of the capacitor C1 that flows rapidly in the primary winding in the transformer T1. The discharge is started in the high-pressure discharge lamp DL by a high voltage pulse generated by superimposing the induced voltage on the output voltage of the DC-DC converter 11, so that the high-pressure discharge lamp DL starts lighting (that is, starts).

  Furthermore, this embodiment is connected between the filter unit 10 and the DC-DC converter 11 and inputs a voltage corresponding to the input voltage Vin to the control unit 2, and a voltage corresponding to the output voltage Vdc. Is input to the control unit 2, and the current flowing to the ground between the DC-DC converter 11 and the inverter 12 (that is, a current substantially equal to the absolute value of the output current from the inverter 12 to the high-pressure discharge lamp DL). (Hereinafter referred to as “output current”), an output current detector 33 that inputs a voltage corresponding to the output current to the controller 2, and an AC component (ripple) connected between the battery E and the filter unit 10 in the input voltage Vin. And a ripple detection unit 34 that generates an output corresponding to the presence or absence of the noise and inputs the output to the control unit 2, and the control unit 2 responds to an input from each of the detection units 31, 32, 33, 34. To work.

  Specifically, the control unit 2 calculates a target current that is a value obtained by dividing a predetermined target power by the output voltage Vdc obtained from the output of the output voltage detection unit 32, and the obtained target current and The control voltage Vop corresponding to the difference from the output current obtained from the output of the output current detector 33 is input to the inverting input terminal of the comparator CP1 of the first drive circuit 11a. As described above, feedback control is achieved so that the power output to the high-pressure discharge lamp DL is the target power.

  The input voltage detection unit 31, the output voltage detection unit 32, and the output current detection unit 33 can all be realized by a well-known technique (for example, a circuit that converts a voltage using an operational amplifier). Is omitted.

  Further, as shown in FIG. 3, the ripple detection unit 34 has a non-inverting input terminal connected to the ground, an input voltage Vin is input to the inverting input terminal via a series circuit of a resistor and a capacitor, and an output terminal. And an inverting input terminal are connected via a parallel circuit of a resistor and a capacitor, and an operational amplifier OP constituting a differentiation circuit that outputs an input differential voltage Vid that is a voltage proportional to a differential value of the input voltage Vin, and an inverting input terminal 4 is inputted with the input differential voltage Vid from the operational amplifier OP, the non-inverting input terminal is inputted with a periodic rectangular wave clock voltage Vcl as shown in FIG. 4 and the output terminal is connected to the control unit 2. Is provided. That is, when the input differential voltage Vid has a waveform as shown by a curve in the upper part of FIG. 4, the input voltage (hereinafter referred to as “ripple detection voltage”) Vrp from the ripple detector 34 to the controller 2 is lower in FIG. The waveform is as shown in FIG. The control unit 2 determines whether or not the battery E is charged based on the ripple detection voltage Vrp input from the ripple detection unit 34.

  By the way, the battery E is charged by a charging circuit (not shown) having a rotor that is linked to the drive system of the automobile and having a generator that generates AC power having a frequency corresponding to the rotational speed of the rotor. Since the charging current from the charging circuit to the battery E includes an AC component having a frequency corresponding to the number of rotations of the rotor of the generator, the input from the battery E during the charging period of the charging circuit. The voltage Vin includes an AC component having the same frequency as the AC component included in the charging current. The control unit 2 determines whether or not an AC component having a frequency corresponding to the charging current is included in the input voltage Vin based on the ripple detection voltage Vrp, and the AC component is included in the input voltage Vin. If it is determined that the battery E is charged, it is determined that the AC component is not included in the input voltage Vin. In other words, it is determined that the battery E is not charged. is there. For example, when the frequency of the clock voltage Vcl is 50 kHz (that is, the cycle is 20 μs), the ripple detection voltage Vrp alternately repeats the L level state and the rectangular wave every four cycles of the clock voltage Vcl as shown in FIG. In this case, the input voltage Vin is considered to contain an AC component having a period of 160 μs (that is, a frequency of 6.25 kHz).

  In the present embodiment, the filter unit 10 is interposed between the DC-DC converter 11 and the ripple detection unit 34, so that noise from the DC-DC converter 11 to the ripple detection unit 34 is attenuated in the filter unit 10. Therefore, erroneous determination due to the noise can be suppressed.

  Hereinafter, the operation of the control unit 2 will be described. In addition, the specific example of each numerical value compared with the input voltage Vin in the operation | movement demonstrated below assumes the case where the rated voltage of the battery E is 12V.

  As shown in FIG. 5, when the power is turned on and the operation is started (S1), the control unit 2 performs an initialization operation of resetting various numerical values used for the operation to a predetermined initial state (S2), Next, based on the input from the input voltage detector 31, it is determined whether or not the input voltage Vin is within a predetermined operating range (9V to 16V in the figure) (S3), and the input voltage Vin is within the operating range. The process does not proceed to the next step S4 until it is determined that there is.

  When it is determined in step S3 that the input voltage Vin is within the operating range, the control unit 2 starts a starting operation for starting the high-pressure discharge lamp DL in the next step S4, and the starting operation is performed. The start time Ton, which is the elapsed time since the start, is started from 0. Specifically, the starting operation is, for example, to lower the operating frequency relatively low (for example, to 100 kHz). During this starting operation, the output voltage Vdc rises once, and the high voltage pulse generated by the starting unit 13 is generated. Thus, after the high pressure discharge lamp DL is started, the output voltage Vdc decreases. During the starting operation, the control unit 2 determines whether or not the output voltage Vdc has reached or exceeded a predetermined starting voltage (400 V in the drawing) necessary for starting the high-pressure discharge lamp DL based on the input from the output voltage detecting unit 33. (S6) Then, it is determined whether or not the output voltage Vdc has dropped below a predetermined lighting determination voltage (220V in the figure) due to the start of the high-pressure discharge lamp DL (S8), and the output voltage Vdc in step S6 is determined. When the starting time Ton reaches 1 second without being determined from the increase to the decrease in the output voltage Vdc in step S8 (Y in S5 or S7), the operations of the DC-DC converter 11 and the inverter 12 are stopped (S9). ). That is, in step S9, the switching elements Q0 to Q4 of the DC-DC converter 11 and the inverter 12 are turned off.

  If it is confirmed in step S8 that the output voltage Vdc has decreased, the control unit 2 proceeds to the next step S10 and starts a steady operation for maintaining the lighting of the high-pressure discharge lamp DL as shown in FIG. . In the steady operation, the operating frequency is higher (for example, 200 kHz) than in the start operation, and the amplitude of the output voltage Vdl from the inverter circuit 12 to the high-pressure discharge lamp DL is the output voltage of the DC-DC converter 11 during the steady operation. It substantially matches Vdc. In addition, the control unit 2 measures the lighting time that is the duration of the steady operation, and is a parameter used to determine the control voltage Vop to be input to the comparator CP1 of the DC-DC converter 11 and to the high-pressure discharge lamp DL. By gradually increasing the target power, which is the target value of the output power, to a predetermined value as the lighting time increases, the output power to the high-pressure discharge lamp DL during the period until the lighting time reaches the predetermined time Is gradually increased, and thereafter the target power is kept constant.

  Further, the control unit 2 monitors the input from the output voltage detection unit 33 (that is, monitors the output voltage Vdc) during the steady operation, and the high pressure discharge lamp DL has disappeared based on the output voltage Vdc. Whether or not (S11) and whether or not a short circuit has occurred (S12, S20).

  The determination of the extinction in step S11 is performed by comparing the output voltage Vdc with the lighting determination voltage (220 V in the figure) used in step S8. That is, if the output voltage Vdc is less than the lighting determination voltage, the control unit 2 determines that the extinction has not occurred, and proceeds to determination of a short circuit in the next step S12. On the other hand, if the output voltage Vdc is equal to or higher than the lighting determination voltage, the control unit 2 determines that the extinction has occurred and stops the operations of the DC-DC converter 11 and the inverter 12 (S13). Then, it is determined whether or not the starting time Ton has reached 3 seconds (S14). If the starting time Ton is 3 seconds or longer in step S14, the control unit 2 returns to step S4 and starts the starting operation again. If the starting time Ton is less than 3 seconds in step S14, the control unit 2 next determines whether or not the starting time Ton has reached 1 second (S15). If the starting time Ton is 1 second or longer in Step S15, that is, if the starting time Ton is 1 second or longer and shorter than 3 seconds, the control unit 2 continues the stop state started in Step S13 as it is (S16). If the starting time Ton is less than 1 second in step S15, the control unit 2 returns to step S3 and restarts the operation from checking whether the input voltage Vin is within the operating range.

  Further, regarding the determination of the short circuit in steps S12 and S20, the output decrease time Tsh, which is the duration of the state in which the output voltage Vdc is lower than the predetermined short circuit determination voltage (20V in the figure), is the predetermined short circuit determination time (FIG. In 1 second), it is determined that a short circuit has occurred. That is, in step S12, the output voltage Vdc is compared with the short-circuit determination voltage. If the output voltage Vdc is equal to or higher than the short-circuit determination voltage, the output decrease time Tsh is stopped (S17), and then the next step S22 (FIG. 1). If the output voltage Vdc is less than the short circuit determination voltage in step S12, it is determined whether or not the output decrease time Tsh is being measured (S18). If not, the output decrease time Tsh is measured from 0. (S19) The process returns to step S11. If the output decrease time Tsh is being measured in step S18, the output decrease time Tsh is compared with the short circuit determination time (S20). If the output decrease time Tsh has not reached the short circuit determination time, the process returns to step S11. If the output decrease time Tsh has reached the short circuit determination time, it is determined that a short circuit has occurred, and the operations of the DC-DC converter 11 and the inverter 12 are stopped (S21).

  The control unit 22 also monitors the input from the input voltage detection unit 31 (that is, monitors the input voltage Vin) during a steady operation. As shown in FIG. 1, the input voltage Vin is compared with a predetermined upper limit voltage Vt (for example, 20V) (S22). If the input voltage Vin is equal to or higher than the upper limit voltage Vt, the operation of the DC-DC converter 11 and the inverter 12 is performed. Each is stopped (S23).

  If the input voltage Vin is lower than the upper limit voltage Vt in step S22, the control unit 2 starts to input the input voltage Vin so that it is necessary to turn off the high-pressure discharge lamp DL from the next step S24. An operation for determining whether or not the voltage is in a low state is started.

  The contents of the operation for determining whether or not the input voltage is in a lowered state, which is the gist of the present invention, will be described below.

  First, the control unit 2 determines whether or not the battery E is charged based on the ripple detection voltage Vrp input from the ripple detection unit 34 (S24). If it is determined that the battery E is charged, the control unit 2 compares the input voltage Vin with a predetermined first lower limit voltage Vb1 (for example, 6V) (S25), and the input voltage Vin is the first lower limit voltage. If it is less than Vb1, it is determined that the input voltage is in a lowered state, and the operation proceeds to step S23 to stop the operations of the DC-DC converter 11 and the inverter 12, respectively. After stopping the counting of the input decrease time Tlv (S26), the process returns to step S11 to continue the steady operation.

  If it is determined in step S24 that the battery E is not charged, the control unit 2 compares the input voltage Vin with a predetermined second lower limit voltage Vb2 lower than the first lower limit voltage Vb1 (S27). If the voltage Vin is greater than or equal to the second lower limit voltage Vb2, the input decrease time Tlv is stopped (S26), the process returns to step S11 and the steady operation is continued. On the other hand, if the input voltage Vin is less than the second lower limit voltage Vb2 in step S27, the control unit 2 next determines whether or not the input decrease time Tlv is being measured (S28). For example, the counting of the input decrease time Tlv starts from 0 (S29), returns to step S11, and continues the steady operation. If the input decrease time Tlv is being measured in step S28, the control unit 2 determines whether or not the input decrease time Tlv has reached a predetermined decrease determination time Tst (for example, 250 ms) (S30). If the input decrease time Tlv reaches the decrease determination time Tst in step S30, the control unit 2 determines that the input voltage is in a decrease state, proceeds to step S23, and determines whether the DC-DC converter 11 and the inverter 12 are connected. Stop each action. If the input decrease time Tlv does not reach the decrease determination time Tst in step S30, the control unit 2 returns to step S11 and continues the steady operation.

  That is, in the present embodiment, during a period when it is determined that the battery E is not charged, a state in which the input voltage Vin is further lower than the second lower limit voltage Vb2 that is lower than the first lower limit voltage Vb1 is a decrease determination time. Since the high pressure discharge lamp DL is not extinguished unless it continues for Tst or more, when the second lower limit voltage Vb2 is set to the first lower limit voltage Vb1 or when the input voltage Vin is lower than the second lower limit voltage Vb2, the step is immediately performed. Compared with the case where the high pressure discharge lamp DL is extinguished in S23, the frequency of extinguishing due to the decrease of the input voltage Vin decreases.

  As shown in FIG. 7, when it is determined in step S24 that the battery E is not charged, a further rapid decrease in the input voltage Vin (hereinafter referred to as “instantaneous low power”) occurs. Step S31 in which the control unit 2 determines whether or not a predetermined third lower limit that is lower than the second lower limit voltage Vb2 when it is determined in Step S31 that an instantaneous low power has occurred. Step S32 for comparing with voltage Vb3 (for example, 3V) is added, and when it is determined in step S31 that an instantaneous low power has not occurred or when the input voltage Vin is greater than or equal to the third lower limit voltage Vb3 in step S32 In step S27, it is determined that an instantaneous low power is generated in step S31, and the input voltage Vin is less than the third lower limit voltage Vb3 in step S32. May be stopped with the DC-DC converter 11 and the inverter 12 immediately proceeds to step S23 regardless of the decrease determination time Tst is performed when. As a specific operation in step S31, for example, when the control unit 2 samples the input voltage Vin every 1 ms, the latest input voltage Vin is a predetermined moment with respect to the input voltage Vin immediately before (that is, 1 ms before). When the low determination voltage (for example, 3 V) is decreased or more, it is determined that an instantaneous low power is generated, and the latest input voltage Vin is not decreased with respect to the immediately preceding input voltage Vin or the decrease width is as described above. If it is less than the instantaneous voltage drop determination voltage, it is determined that no instantaneous low power has occurred. That is, the decrease rate of the input voltage Vin is equal to or higher than the determination decrease rate (3 V / ms in the above example) that is a value obtained by dividing the instantaneous voltage drop determination voltage at the sampling interval of the input voltage Vin (1 ms in the above example). When it becomes, it is determined that an instantaneous low power has occurred, and conversely, it is determined that no instantaneous low power has occurred when the rate of decrease of the input voltage Vin becomes less than the above-mentioned determination rate. If the above configuration is adopted, compared with the case where the stop based on the comparison result between the input voltage Vin and the third lower limit voltage Vb3 in step S31 is not performed, the operation with low efficiency is continued in the state where the input voltage Vin is lowered. It can be suppressed. Further, the determination of the instantaneous low power in step S31 may be omitted, and the immediate stop when the input voltage Vin falls below the third lower limit voltage Vb3 may be performed regardless of the presence or absence of the instantaneous low power.

  Here, the electric light source is not limited to the high pressure discharge lamp DL, and for example, a light emitting diode LED may be used as shown in FIG. In this case, none of the inverter 12, the starter 13, and the starter power supply unit 14 are necessary, and in the example of FIG. 8, the light emitting diode LED is directly connected between the output terminals of the DC-DC converter 11. In the case of FIG. 8, only the DC-DC converter 11 constitutes the power converter in the claims.

  Further, in the case where the high pressure discharge lamp DL is used as the electric light source, the control unit 2 continues for a predetermined time after it is determined that instantaneous low power is generated in a state where it is determined that the battery E is not charged. However, the output power to the high-pressure discharge lamp DL may be temporarily increased. If this configuration is adopted, the high-pressure discharge lamp DL disappears as compared with the case where the output power is not increased as described above. Is suppressed. As a specific operation in which the control unit 2 increases the output power of the high-pressure discharge lamp DL, for example, an operation of temporarily increasing the target power or an output current obtained from the output of the output current detection unit 33 is subtracted. As a result, the output power is increased by using the control voltage Vop for the calculation of the control voltage Vop, or the output power is increased with respect to the control voltage Vop obtained as a result of the calculation. For example, an operation of inputting the first drive circuit 11a of the DC-DC converter 11 after correction is considered. When the rated power of the high pressure discharge lamp DL is 35 W and the input power to the high pressure discharge lamp DL is allowed to be 32 W to 38 W of the rated power plus or minus 3 W, the increase amount of the output power due to the above operation is, for example, 2 W. .

  By the way, when the high-pressure discharge lamp DL is used as an electrical light source, when the polarity of the output of the inverter 12 is inverted, the extinction is likely to occur at the dead time (zero cross point) of the output voltage of the inverter 12. Therefore, the controller 2 determines the operating frequency (that is, the frequency of the output of the inverter 12) for a predetermined time after it is determined that the instantaneous low power is generated while it is determined that the battery E is not charged. It is also possible to suppress the extinction of the high-pressure discharge lamp DL by temporarily reducing it, that is, by reducing the number of occurrences of the dead time per unit time (the number of zero cross points). For example, inversion of the polarity of the output of the inverter 12 is stopped for a period of 20 cycles after it is determined that the battery E is not charged and an instantaneous low power is generated, and then the polarity of the output of the inverter 12 is stopped. Inverting the polarity of the output of the inverter 12 is stopped for another 20 cycles after the inversion. In this case, the operating frequency is set to 1/40 over a period of 40 cycles. Note that the polarity of the output of the inverter 12 is fixed for a predetermined time after it is determined that the battery E is not charged and an instantaneous low power is generated, and the output from the inverter 12 to the high-pressure discharge lamp DL is set to DC. In this case, the duration of the decrease in the operating frequency is set to one half of the output cycle of the inverter 12 during the decrease in the operating frequency (that is, the reciprocal of the operating frequency). However, in order to avoid the occurrence of a temperature difference between the electrodes of the high-pressure discharge lamp DL due to an imbalance in the duration of each polarity of the output of the inverter 12, the duration of the temporary decrease in the operating frequency as described above In this case, the duration of each polarity of the output of the inverter 12 can be made equal by setting it to an integral multiple of the output cycle of the inverter 12 (that is, the reciprocal of the operation frequency) when the operating frequency is temporarily lowered. desirable.

  Further, the control unit 2 determines that the battery E is always charged during a period in which noise is likely to occur in the DC-DC converter 11 or the inverter 12 that is a power conversion unit (hereinafter referred to as “noise generation period”). You may make it do. As the noise generation period, for example, the inversion of the output voltage Vdl from the inverter 12 to the high-pressure discharge lamp DL can be considered. For example, with respect to the output voltage Vdl of the inverter 12 as shown in the upper part of FIG. 9, as shown in the lower part of FIG. 9, the L level only during a short time (for example, during the dead time) including the inversion of the output voltage Vdl of the inverter 12 And a mask generation unit (not shown) that generates a rectangular wave mask voltage Vma that is at H level in other periods, and the control unit 2 is a period in which the mask voltage Vma is at H level in step S24. Whether or not the battery E is charged is determined using the output of the ripple detection circuit 34 only during the period, and the battery E is charged regardless of the output of the ripple detection circuit 34 while the mask voltage Vma is at the L level. Is determined. If this configuration is adopted, inefficient operation when the input voltage Vin is lower than the first lower limit voltage Vb1 because it is erroneously determined that there is no charge due to the above-mentioned noise even though the battery E is actually charged. Can be avoided. Even when a light emitting diode LED is used as a light source as shown in FIG. 8, if a noise source that periodically generates noise exists and the noise generation period of the noise source is known, the noise source By providing a mask generation unit that generates a mask voltage Vma that becomes L level during the noise generation period, the operation in a state where the input voltage Vin is low due to the erroneous determination as described above due to noise of the noise source is continued. Can be avoided.

2 control unit 10 filter unit 11 DC-DC converter (a part or all of the power conversion unit in the claims)
12 Inverter (part of power converter and noise source in claims)
31 Input voltage detector 34 Ripple detector DL High pressure discharge lamp (electrical light source in claims)
E battery LED light emitting diode (electrical light source in claims)

Claims (6)

A vehicle-mounted lighting device that lights an electrical light source using a battery mounted on a vehicle and charged by a charging current including an AC component as a power source,
A power converter that turns on the electrical light source by converting the power input from the battery and outputting it to the electrical light source; and
An input voltage detection unit for detecting an input voltage from the battery to the power conversion unit;
A ripple detection unit that generates an output corresponding to an AC component included in the input voltage from the battery to the power conversion unit;
A control unit that determines whether or not the battery is charged based on the output of the ripple detection unit, and that controls the power conversion unit according to the input voltage detected by the input voltage detection unit and the determination result of the presence or absence of charging; With
The control unit determines that the battery is not charged when the input voltage detected by the input voltage detection unit falls below a predetermined first lower limit voltage while it is determined that the battery is charged. When the state where the input voltage detected by the input voltage detection unit is lower than the predetermined second lower limit voltage lower than the first lower limit voltage continues for a predetermined decrease determination time or longer, the electric power conversion unit An on-vehicle lighting device characterized in that output of electric power to a general light source is stopped.   The control unit calculates an input decrease rate, which is a decrease width per unit time, of the input voltage detected by the input voltage detection unit as needed, and the input decrease rate is determined in a state where it is determined that the battery is not charged. When the input voltage detected by the input voltage detector is compared with a predetermined third lower limit voltage lower than the second lower limit voltage, and the input voltage is less than the third lower limit voltage. The in-vehicle lighting device according to claim 1, wherein output of electric power from the power conversion unit to the electric light source is stopped without waiting for the elapse of the decrease determination time.   The in-vehicle lighting device according to claim 1, further comprising a filter unit that suppresses input of noise from the power conversion unit to the ripple detection unit. The electrical light source connected to the power converter is a discharge lamp,
The control unit calculates an input decrease rate, which is a decrease width per unit time, of the input voltage detected by the input voltage detection unit as needed, and the input decrease rate is determined in a state where it is determined that the battery is not charged. The in-vehicle lighting device according to any one of claims 1 to 3, wherein the output power of the power conversion unit is temporarily increased over a predetermined time from when the determination lowering speed is exceeded. The power conversion unit outputs AC power to a high-pressure discharge lamp as an electrical light source,
The control unit calculates an input decrease rate, which is a decrease width per unit time, of the input voltage detected by the input voltage detection unit as needed, and the input decrease rate is determined in a state where it is determined that the battery is not charged. The in-vehicle lighting device according to any one of claims 1 to 4, wherein the frequency of the output of the power conversion unit is reduced for a predetermined time from when the determination lowering speed is exceeded. The power conversion unit includes a noise source that periodically generates noise,
6. The control unit according to claim 1, wherein the control unit determines that the battery is charged regardless of the output of the ripple detection unit during a period in which noise from the noise source occurs. The vehicle-mounted lighting device described.

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