WO2014125756A1 - 電力供給装置 - Google Patents
電力供給装置 Download PDFInfo
- Publication number
- WO2014125756A1 WO2014125756A1 PCT/JP2014/000073 JP2014000073W WO2014125756A1 WO 2014125756 A1 WO2014125756 A1 WO 2014125756A1 JP 2014000073 W JP2014000073 W JP 2014000073W WO 2014125756 A1 WO2014125756 A1 WO 2014125756A1
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- WIPO (PCT)
- Prior art keywords
- power supply
- ground fault
- load
- voltage drop
- led
- Prior art date
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Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/32—Means for protecting converters other than automatic disconnection
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/52—Testing for short-circuits, leakage current or ground faults
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/16—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to fault current to earth, frame or mass
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/08—Limitation or suppression of earth fault currents, e.g. Petersen coil
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/30—Driver circuits
- H05B45/37—Converter circuits
- H05B45/3725—Switched mode power supply [SMPS]
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/50—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60Q—ARRANGEMENT OF SIGNALLING OR LIGHTING DEVICES, THE MOUNTING OR SUPPORTING THEREOF OR CIRCUITS THEREFOR, FOR VEHICLES IN GENERAL
- B60Q11/00—Arrangement of monitoring devices for devices provided for in groups B60Q1/00 - B60Q9/00
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/40—Testing power supplies
Definitions
- the present disclosure relates to a power supply apparatus suitable for use in supplying power to, for example, an LED unit.
- Patent Document 1 describes a driver circuit (power supply device) that supplies power to an LED (light emitting diode) employed as a vehicle headlight.
- this circuit includes a DCDC converter 40 x that boosts the battery voltage and supplies power to the LED 10, and a shunt resistor Rs connected to the cathode side (low potential side) of the LED 10.
- the DCDC converter 40x detects the drive current (see arrow Y1 in the figure) flowing to the LED 10 based on the voltage drop amount generated in the shunt resistor Rs, and supplies power to the LED 10 so that the detected value becomes a target value. Feedback control the amount.
- the detection value by the shunt resistor Rs does not become a value corresponding to the drive current, and thus the feedback control cannot be normally performed. That is, when a ground fault occurs, most of the drive current flowing through the LED 10 flows to the ground fault side, so that the detection value by the shunt resistor Rs is lower than the value commensurate with the drive current. Then, since feedback control is performed to increase the detected value to the target value, the drive current increases more and there is a concern that excessive drive current flows and damages the LED 10.
- the circuit 30x stops the operation of the DCDC converter 40x.
- the present disclosure has been made in view of the above problems, and the purpose thereof is to suppress an excessive drive current from flowing to a load (for example, an LED) to which power is supplied even when a ground fault occurs.
- An object of the present invention is to provide a power supply device that can be used.
- a power supply device supplies DC power to a load (10), and is connected to a shunt resistor connected in series on the low potential side of the load and a voltage drop generated by the shunt resistor. It is generated when power supply control means for controlling the power supply state to the load, a ground fault detection element that is connected in series to the low potential side of the load to cause a voltage drop, and a detection current is supplied to the ground fault detection element When the voltage drop amount is less than a predetermined threshold value, it is assumed that a ground fault has occurred, and limiting means for limiting power supply by the power supply means is provided.
- the amount of voltage drop generated in the ground fault detection element when the detection current is supplied should be small if a ground fault occurs. Therefore, according to this aspect, a ground fault can be detected without flowing an excessive drive current to the load, and an excessive power supply to the load can be limited in advance.
- the voltage drop caused by the ground fault detection element is the voltage generated by the ground fault resistance. Larger value than the amount of descent. Therefore, even when a ground fault occurs in a state where the ground fault resistance is large, the ground fault can be detected.
- FIG. 2 is a diagram showing current-voltage characteristics of the diode of FIG. 1.
- the flowchart of control in 2nd Embodiment. The circuit diagram of the electric power supply apparatus concerning 3rd Embodiment of this indication.
- the circuit diagram of the electric power supply apparatus concerning 4th Embodiment of this indication. The flowchart of control in 4th Embodiment.
- the flowchart of control in 5th Embodiment The circuit diagram of the electric power supply apparatus concerning 6th Embodiment of this indication.
- the LED unit 10 shown in FIG. 1 includes a plurality of light emitting diodes (LEDs 11), and is applied as, for example, a headlamp mounted on a vehicle.
- the LED driver 20 that supplies DC power to these LEDs 11 (load) corresponds to the power supply device according to the present embodiment.
- the LED driver 20 boosts or lowers the voltage of the battery 12 mounted on the vehicle and supplies power to the LED 11. Specifically, the battery voltage of about 12V is boosted or stepped down to about 10V to 30V and applied to the LED 11.
- the load side terminals 21 and 22 of the LED driver 20 are connected to the anode side terminal and the cathode side terminal of the LED 11, respectively.
- the battery side terminals 23 and 24 of the LED driver 20 are connected to the positive terminal and the negative terminal of the battery 12, respectively, and the battery side terminal 24 on the negative terminal side is grounded to 0V.
- the LED driver 20 includes a DCDC converter 40 having a step-up / step-down circuit that boosts or lowers the battery voltage, and a shunt resistor Rs connected in series to the low potential side of the LED unit 10. As the drive current flowing through the LED unit 10 increases, the amount of voltage drop generated by the shunt resistor Rs increases. That is, the voltage drop amount is a value corresponding to the drive current.
- this voltage drop amount or a value obtained by converting the drop amount into the drive current is referred to as a “shunt resistance detection value”.
- the DCDC converter 40 controls the amount of power supplied to the LED unit 10 based on the detected shunt resistance value.
- the DCDC converter 40 has a control circuit that controls the output voltage so that the shunt resistance detection value becomes the target value, and functions as “power supply control means”.
- feedback control is performed so that the drive current becomes a constant target value even if the resistance value of the LED 11 fluctuates or the battery voltage fluctuates due to the environmental temperature change.
- the DCDC converter 40 when the DCDC converter 40 controls the duty of the on-time or off-time by switching on / off of the output current at a predetermined cycle, the DCDC converter 40 detects the shunt resistance. The duty is feedback controlled based on the value.
- the LED driver 20 includes a ground fault detection diode D (ground fault detection element), a ground fault detection circuit 30 and a detection current output circuit 31 described below.
- the diode D is connected in series to the low potential side of the LED unit 10. Specifically, the diode D is connected in series between the shunt resistor Rs and the LED unit 10, the cathode terminal of the diode D is connected to the shunt resistor Rs side, and the anode terminal of the diode D is connected to the cathode side of the LED unit 10. It is connected.
- the detection current output circuit 31 is a circuit that applies a detection voltage to the diode D and causes the detection current to flow.
- the value of the constant voltage is set to a value lower than the battery voltage.
- the microcomputer drive voltage (5 V) is used as the detection voltage.
- the ground fault detection circuit 30 detects the ground fault by detecting the voltage drop caused by the diode D and the shunt resistor Rs and determining the presence or absence of the ground fault on the cathode side of the LED unit 10 based on the detected value. To do. Specifically, if the detected voltage drop amount is less than a preset threshold value, it is determined that a ground fault has occurred. When a ground fault is detected, a stop command signal is output to the DCDC converter 40 so as to stop the operation of the DCDC converter 40. When a ground fault is not detected, a permission signal for permitting output of the drive current is output. Is output to the DCDC converter 40.
- This ground fault determination is performed prior to supplying power to the LED unit 10. Then, when the voltage drop detected by the ground fault detection circuit 30 is equal to or greater than the first threshold, the permission signal is output, and the driving current is output from the DCDC converter 40 to allow the LED unit 10 to be lit. . On the other hand, if it is less than the first threshold, the stop command signal is output, and the operation is limited so that the LED unit 10 does not light up.
- the ground fault determination is performed even during the operation of the LED unit 10. That is, even when the voltage drop detected by the ground fault detection circuit 30 becomes less than the second threshold value, the stop command signal is output, and the drive current is stopped or decreased to stop the current application to the LED unit 10. Or restrict.
- the second threshold value TH2 is set to a value higher than the first threshold value TH1.
- the detection current output circuit 31 may always output the detection current, may stop the output while supplying power to the LED unit 10, or does not require a power supply to the LED unit 10 and determines a ground fault. When there is no need for the output, the output may be stopped.
- the current output from the DCDC converter 40 flows in order through the LED unit 10, the diode D, and the shunt resistor Rs, and then flows to the battery 12 through the battery side terminal 24 (see arrow Y1).
- the shunt resistance detection value is lower than the value commensurate with the drive current. Note that the greater the ground fault resistance Ra, the closer the shunt resistance detection value is to the normal value when no ground fault occurs.
- the detection current output from the detection current output circuit 31 sequentially flows through the diode D and the shunt resistor Rs, and then flows to the battery 12 through the battery side terminal 24 (see arrow Y3). However, if the ground fault occurs, the detected current flows into the ground fault side (see arrow Y4).
- the current-voltage characteristic of the diode D is non-linear. That is, when the current flowing through the diode D is large, the electrical resistance of the diode D becomes small. Therefore, under the condition where a large current (about 1 A) is supplied to the diode D by supplying power to the LED unit 10, the drive current can be supplied with low heat generation and low loss.
- the ground fault detection element is a diode (D) whose cathode side is connected to the low potential side. That is, apart from the shunt resistor Rs, a diode D that generates a constant voltage drop is connected in series to the low potential side of the LED unit 10.
- the diode D generally has a non-linear characteristic shown in FIG. Therefore, when the LED unit 10 is stopped, a large voltage drop occurs even when a small detection current is applied, so that the ground fault detection accuracy can be improved.
- the LED unit 10 when the LED unit 10 is turned on, even if a drive current that is larger than the detected current flows through the diode D, the characteristic occurs in the diode D compared to the case where the linear ground fault detecting element is used. The voltage drop can be reduced. Therefore, the amount of power loss caused by the diode D when the LED unit 10 is turned on can be reduced.
- this embodiment is characterized by including a detection current output circuit 31 that outputs a detection current to a diode D (ground fault detection element).
- the output circuit 31 for detection current is provided separately from the DCDC converter 40 as means for outputting electric power, the detection current can be supplied to the diode D without supplying the drive current to the LED unit 10. Therefore, it is possible to reliably avoid a drive current flowing to the LED unit 10 in a grounded state.
- the diode D (ground fault detection element) is connected in series to the high potential side of the shunt resistor Rs.
- the drive current is set to the target value when the DCDC converter 40 performs feedback control using the detected shunt resistor value.
- the accuracy of control deteriorates for the following reasons. That is, when the diode D is connected to the low potential side of the shunt resistor Rs, the potential on the low potential side of the shunt resistor Rs does not become the GND potential of the LED driver 20 but is offset by the voltage drop generated in the diode D. Get higher. Therefore, since it is necessary to calculate the drive current in consideration of the offset, the calculation accuracy is deteriorated. Alternatively, the detection circuit becomes complicated.
- the calculation accuracy of the drive current can be improved with a simple circuit, and consequently The accuracy of feedback control can be improved.
- the ground fault detection circuit 30 supplies power from the DCDC converter 40 (power supply means) to the LED unit 10 when a request for operating the LED unit 10 (load) occurs.
- a voltage drop amount is detected in advance, and power supply by the DCDC converter 40 is permitted when the detected voltage drop amount is equal to or greater than a threshold value.
- the LED driver 20 of the first embodiment includes a detection current output circuit 31 that outputs a detection current to the diode D.
- the LED driver 20A of this embodiment shown in FIG. 3 is configured such that the DCDC converter 40 outputs a detection current to the diode D, and the detection current output circuit 31 is eliminated. That is, the DCDC converter 40 (power supply means) outputs a detection current to the diode D (ground fault detection element) prior to power supply to the LED unit 10 (load).
- the detected current in this case is not a drive current based on feedback control based on the detected value of the shunt resistance of the DCDC converter 40, but a minute drive current based on an operation with a preset fixed duty.
- FIG. 4 is a flowchart showing a control procedure of the LED driver 20A according to the present embodiment. This control is performed by the control means of the DCDC converter 40 when the ignition switch of the vehicle is turned on or when the lighting switch of the LED unit 10 is turned on.
- step S10 of FIG. 10 power is turned on to the LED driver 20A in step S10 of FIG.
- step S11 the fixed DUTY mode in which the duty ratio is fixed and output is set so as to output the minute amount of drive current described above. In this mode, feedback control based on the detected shunt resistance value is prohibited.
- step S12 it is determined whether or not the cathode voltage of the LED 11 (that is, the voltage on the low voltage side of the LED unit 10) is equal to or higher than a predetermined voltage Vth.
- This LED cathode voltage corresponds to the amount of voltage drop caused by the diode D and the shunt resistor Rs.
- step S13 the mode is switched to a feedback control mode in which feedback control based on the shunt resistance detection value is performed.
- the LED cathode voltage ⁇ Vth S12: NO
- Tth Tth
- the detection current is passed through the LED unit 10 in a state where it is not determined whether or not a ground fault has occurred, a current is supplied to the LED unit 10 in a state where a ground fault has occurred. May flow.
- the detection current is passed in a state where the feedback control is prohibited and the detection current is set to a minute amount, even if the detection current flows to the LED unit 10 in the ground fault state, the detection current Thus, the LED unit 10 is not damaged.
- the detection current output circuit 31 shown in FIG. 1 is abolished and the LED driver 20 ⁇ / b> A is configured to enable ground fault detection while avoiding excessive drive current from flowing to the LED unit 10. This can be realized while simplifying the configuration.
- the LED driver 20 ⁇ / b> B of the present embodiment includes a switching element 50 connected in parallel with the diode D, and turns on the switching element 50 when supplying power to the LED unit 10, Control means 60 for turning off switching element 50 when power supply is stopped is provided.
- MOSFET Metal-Oxide-Semiconductor Field Effect Transistor
- bipolar transistor bipolar transistor
- IGBT Insulated Gate Bipolar Transistor
- the microcomputer 60 controls the on / off operation of the MOSFET 50 by controlling the gate terminal voltage of the MOSFET 50.
- the MOSFET 50 When the power supply to the LED unit 10 is stopped, the MOSFET 50 is turned off, so that the detection current flows through the diode D as indicated by a one-dot chain line Y3 in the figure. Thereby, the effect similar to 1st Embodiment shown in FIG. 1 is exhibited. That is, since a large voltage drop occurs in the diode D with respect to a minute detection current, it becomes possible to detect a drop in the voltage drop when a ground fault occurs as shown by the dotted line Y4, and to improve the ground fault detection accuracy. It can be improved.
- the LED driver 20C of the present embodiment is a modification of the LED driver 20B of FIG. 5, and is divided resistors R2, R3 between the drain and gate of the MOSFET 50 of the LED driver 20B and between the gate and source.
- the diode D can be eliminated.
- the ground fault detection element is the MOSFET 50C.
- the control unit 60C is configured to turn on the MOSFET 50C when power is supplied to the LED unit 10 and to operate the gate of the MOSFET 50C to be in a high impedance state when power supply to the LED unit 10 is stopped.
- MOSFET50C is employ
- microcomputer 60 is used as the control means 60C.
- the microcomputer 60 controls the operation of the MOSFET 50C by controlling the gate voltage of the MOSFET 50C. Specifically, control is performed so that the operation of MOSFET 50C is switched to any one of the Hi impedance ON state, the normal ON state, and the OFF state described below.
- the state where the drain-source current is cut off by controlling the gate-source voltage to 0 V is the “off state”.
- a state in which the gate-source voltage is controlled to a voltage equal to or higher than the gate threshold voltage (for example, 5 V) and the drain-source is energized with a low resistance is the “normally on state”.
- a state in which the gate is controlled to be in the Hi impedance state and energized while causing a voltage drop corresponding to the gate threshold voltage between the drain and the source is the “Hi impedance on state”.
- FIG. 7 is a flowchart showing a control procedure of the LED driver 20C according to the present embodiment.
- power is turned on to the LED driver 20C in step S20 of FIG.
- control is performed so that the gate of the MOSFET 50C has Hi impedance. That is, the MOSFET 50C is operated in the Hi impedance on state.
- a detection current is output from the detection current output circuit 31.
- the detected current may be constantly output even during the operation of the LED unit 10, or the output may be stopped during the operation.
- the cathode voltage of the LED 11 (that is, the voltage on the low voltage side of the LED unit 10) is equal to or higher than a predetermined voltage Vth.
- This LED cathode voltage corresponds to the amount of voltage drop generated in the MOSFET 50C and the shunt resistor Rs.
- step S26 When the DCDC converter 40 starts operating in step S24, it is determined in subsequent step S26 whether or not the output current of the LED 11 is within the normal range based on the shunt resistance detection value. If it is determined to be within the normal range (S26: YES), the control signal output from the microcomputer 60C is increased to a voltage (5 V) that is equal to or higher than the gate threshold in the subsequent step S27. That is, the MOSFET 50C is normally operated in an on state. On the other hand, if it is determined to be out of the normal range (S26: NO), the Hi impedance on state is continued in the subsequent step S28.
- step S29 it is determined in step S29 whether the output current of the LED 11 is excessive based on the shunt resistance detection value. If it is determined to be excessive (S29: YES), the control signal output from the microcomputer 60C is set to Lo (0 V), and the MOSFET 50C is turned off. On the other hand, if it is not determined to be excessive (S29: NO), the normally on state is continued in the subsequent step S28.
- the MOSFET 50C when the power supply to the LED unit 10 is stopped, the MOSFET 50C is set in the Hi impedance ON state, so that the detection current flows between the drain and the source of the MOSFET 50C as indicated by a dashed line Y3 in the figure.
- the effect similar to 1st Embodiment shown in FIG. 1 is exhibited. That is, since a large voltage drop occurs in the MOSFET 50C with respect to a minute detection current, it becomes possible to detect a drop in the voltage drop when a ground fault occurs as shown by the dotted line Y4, and improve the ground fault detection accuracy. it can. That is, it is possible to eliminate the diode D shown in FIG. 5 and simplify the configuration of the LED driver 20C, while enabling ground fault detection while avoiding excessive drive current from flowing to the LED unit 10.
- the MOSFET 50C is normally turned on when power is supplied to the LED unit 10, when a large current (drive current) from the LED unit 10 flows through the MOSFET 50C as shown by the solid line Y1, power loss generated in the MOSFET 50C can be reduced.
- the present embodiment is characterized in that the microcomputer 60C (control means) turns off the MOSFET 50C (field effect transistor) when it is considered that an excessive drive current is output.
- the DCDC converter 40 when a ground fault is detected during operation of the LED unit 10, the DCDC converter 40 is stopped and an excessive drive current is supplied to the LED unit 10. I try to avoid the flow.
- the MOSFET 50C when an excessive drive current is detected (S29: YES), the MOSFET 50C is turned off (S30), so that fail-safe can be doubled. Therefore, even if the DCDC converter 40 fails, it is possible to prevent an excessive drive current from flowing through the LED unit 10 by turning off the MOSFET 50C.
- the LED driver 20D of the present embodiment is a modification of the LED driver 20 of FIG. 1, and the diode D (ground fault detection element) of the LED driver 20 is replaced with an N-channel MOSFET 50D. .
- the ground fault detection element is the MOSFET 50D
- the MODFET 50D is connected so that the source side of the MOSFET 50D is located on the LED unit 10 (load) side. That is, the MOSFETs 50 and 50C shown in FIGS. 5 and 6 are connected in the opposite direction, and the MODFET 50D is turned on when power is supplied to the LED unit 10, and the field effect transistor 50D is turned off when power supply to the LED unit 10 is stopped.
- a microcomputer 60D control means to be operated is provided.
- the microcomputer 60D controls the operation of the MOSFET 50D by controlling the gate terminal voltage of the MOSFET 50D. Specifically, control is performed such that the operation of MOSFET 50 is switched to either the above-described normal on state or off state.
- FIG. 9 is a flowchart showing a control procedure of the LED driver 20D according to the present embodiment.
- power is turned on to the LED driver 20D in step S40 of FIG.
- MOSFET 50D is turned off. In this off state, the parasitic diode of the MOSFET 50D functions in the same manner as the diode D of FIG.
- the detection current output circuit 31 outputs the detection current.
- the detected current may be constantly output even during the operation of the LED unit 10, or the output may be stopped during the operation.
- the cathode voltage of the LED 11 (that is, the low voltage side voltage of the LED unit 10) is equal to or higher than a predetermined voltage Vth.
- This LED cathode voltage corresponds to the amount of voltage drop caused by the MOSFET 50D and the shunt resistor Rs.
- step S46 it is determined in the subsequent step S46 whether or not the output current of the LED 11 is equal to or greater than a predetermined value Ith based on the shunt resistance detection value. If it is determined that the value is equal to or greater than the predetermined value (S46: YES), it is considered that the drive current is normally output, and the MOSFET 50D is normally operated in step S47. On the other hand, if it is determined that it is less than the predetermined value (S46: NO), the MOSFET 50D is kept off in the subsequent step S48.
- the parasitic diode of the MOSFET 50D As for the parasitic diode of the MOSFET 50D, the characteristics of the detection current and the voltage drop amount are nonlinear as in the diode D of FIG. When the power supply to the LED unit 10 is stopped, the MOSFET 50D is turned off, so that a large voltage drop is caused by the parasitic diode with respect to a minute detection current. Therefore, the ground fault detection accuracy can be improved. On the other hand, since the MOSFET 50D is turned on when power is supplied to the LED unit 10, the electrical resistance when a large current (drive current) from the LED unit 10 flows through the MOSFET 50D can be made extremely small. Therefore, it is possible to avoid a large power loss caused by the parasitic diode when the LED unit 10 is driven.
- the LED driver 20 ⁇ / b> E of the present embodiment is a modification of the LED driver 20 of FIG. Have changed.
- the LED driver 20E of the present embodiment includes a ground fault detection circuit 30E (change means) that changes the threshold value to a larger value than when the power supply is stopped when the power is supplied to the LED unit 10 (load). To do.
- a ground fault detection circuit 30E change means
- the ground fault detection circuit 30E determines whether or not the cathode voltage of the LED 11 (that is, the voltage on the low voltage side of the LED unit 10) is greater than or equal to the thresholds TH1 and TH2. This LED cathode voltage corresponds to the amount of voltage drop caused by the diode D and the shunt resistor Rs.
- FIG. 11A shows the first threshold value TH1 when the operation of the DCDC converter 40 is turned off and the power supply to the LED unit 10 is stopped.
- the first threshold value TH1 is set to a value lower than the theoretical value (for example, 0.7 V) of the voltage drop amount generated in the diode D at the normal time when no ground fault has occurred. If a ground fault occurs, the amount of voltage drop becomes lower than the threshold value TH1, and it is determined that a ground fault has occurred.
- FIG. 11B shows the second threshold value TH2 when the DCDC converter 40 is turned on to supply power to the LED unit 10.
- This second threshold value TH2 is lower than the theoretical value (for example, 0.9 V) of the voltage drop caused by the diode D and the shunt resistor Rs at the normal time when no ground fault has occurred, and is higher than the first threshold value when the supply is stopped. Is set to a value.
- the comparator 32 included in the ground fault detection circuit 30E compares the cathode voltage (voltage drop amount) of the LED 11 with the threshold values TH1 and TH2, and if the voltage drop amounts ⁇ TH1 and TH2, it is considered that a ground fault has occurred.
- the operation stop command signal is output to the DCDC converter 40.
- the voltage drop amount ⁇ TH1 and TH2 it is considered that a ground fault has not occurred, and an operation permission signal is output to the DCDC converter 40.
- the ground fault detection circuit 30E acquires the shunt resistance detection value and switches the thresholds TH1 and TH2 used in the comparator 32 according to the acquired value. That is, if the shunt resistance voltage value is 0 V, the power supply to the LED unit 10 is stopped. In this case, the first threshold value TH1 is switched. On the other hand, if the shunt resistance voltage value is a voltage (about 0.2 V) supplying power to the LED unit 10, the switching is performed so that the second threshold value TH2 is used.
- the voltage drop amount may be higher than the first threshold value TH1. Therefore, if the ground fault determination is performed using the first threshold value TH1 even during power supply, there is a concern that the leak state cannot be detected.
- the normal value of the voltage drop amount is larger than when the power supply is stopped when the power is supplied, and the threshold value is changed to be larger than that when the power supply is stopped. Therefore, even if the above-described ground fault occurs in the leak state, the ground fault can be detected with high accuracy.
- the ground fault detection circuit 30 detects the presence or absence of a ground fault based on the voltage drop amount at the shunt resistor Rs and the diode D. You may comprise so that it may detect.
- the operation of the DCDC converter 40 is stopped and restricted in each of the above embodiments.
- a predetermined amount of drive current output may be permitted, and the LED unit 10 may be lit at a lower luminance than normal.
- the electric power supply object (load) by LED driver is the LED unit 10 provided with LED11
- the load is not limited to that mounted on the vehicle.
- the diode D (ground fault detection element) is connected in series to the high potential side of the shunt resistor Rs, but the diode D may be connected in series to the low potential side of the shunt resistor Rs.
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Circuit Arrangement For Electric Light Sources In General (AREA)
- Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
- Lighting Device Outwards From Vehicle And Optical Signal (AREA)
- Emergency Protection Circuit Devices (AREA)
- Dc-Dc Converters (AREA)
Abstract
Description
図1に示すLEDユニット10は、複数の発光ダイオード(LED11)を有して構成されており、例えば車両に搭載された前照灯として適用される。これらのLED11(負荷)へ直流の電力を供給するLEDドライバ20が、本実施形態にかかる電力供給装置に相当する。LEDドライバ20は、車両に搭載されているバッテリ12の電圧を昇圧または降圧して、LED11へ電力供給する。具体的には、約12Vのバッテリ電圧を10V~30V程度にまで昇圧または降圧してLED11に印加する。
上記第1実施形態のLEDドライバ20は、ダイオードDへ検知電流を出力する検知電流出力回路31を備えている。これに対し、図3に示す本実施形態のLEDドライバ20Aは、DCDCコンバータ40がダイオードDへ検知電流を出力するように構成されており、検知電流出力回路31を廃止している。つまり、DCDCコンバータ40(電力供給手段)は、LEDユニット10(負荷)への電力供給に先立ち、ダイオードD(地絡検知素子)へ検知電流を出力することを特徴とする。この場合の検知電流は、DCDCコンバータ40のシャント抵抗検出値に基づくフィードバック制御による駆動電流ではなく、予め設定しておいた固定デューティでの動作による微小な駆動電流である。
図5に示すように、本実施形態のLEDドライバ20Bは、ダイオードDと並列接続されたスイッチング素子50を備え、LEDユニット10への電力供給時にはスイッチング素子50をオン作動させ、LEDユニット10への電力供給停止時にはスイッチング素子50をオフ作動させる制御手段60を備えることを特徴とする。
Field Effect Transistor)やバイポーラトランジスタ、IGBT(Insulated Gate Bipolar Transistor)等が挙げられる。図5の例では、nチャネル型のMOSFET50をスイッチング素子として用いており、また、マイクロコンピュータ(マイコン60)を前記制御手段として用いている。マイコン60は、MOSFET50のゲート端子電圧を制御することで、MOSFET50のオンオフ作動を制御する。
図6に示すように、本実施形態のLEDドライバ20Cは、図5のLEDドライバ20Bの変形例であり、LEDドライバ20BのMOSFET50のドレイン-ゲート間、およびゲート-ソース間に分割抵抗R2、R3を設けることで、ダイオードDの削除を実現させている。
図8に示すように、本実施形態のLEDドライバ20Dは、図1のLEDドライバ20の変形例であり、LEDドライバ20のダイオードD(地絡検知素子)をNチャネル型のMOSFET50Dに置き換えている。
図10に示すように、本実施形態のLEDドライバ20Eは、図1のLEDドライバ20の変形例であり、地絡検出回路30Eによる地絡判定に用いる閾値を、LEDユニット10の作動状態に応じて変更している。
本開示は、実施形態に準拠して記述されたが、当該実施形態や構造に限定されるものではない。本開示は、様々な変形例や均等範囲内の変形をも包含する。加えて、様々な組み合わせや形態、さらには、それらに一要素のみ、それ以上、あるいはそれ以下、を含む他の組み合わせや形態をも、本開示の範疇や思想範囲に入るものである。
Claims (11)
- 負荷(10)へ直流の電力を供給する電力供給装置(20、20A、20B、20C、20D、20E)において、
前記負荷の低電位側に直列接続されたシャント抵抗(Rs)と、
前記シャント抵抗で生じる電圧降下量に応じて、前記負荷への電力供給状態を制御する電力供給制御手段(40)と、
前記負荷の低電位側に直列接続されて電圧降下を生じさせる地絡検知素子(D、50C、50D、50E)と、
前記地絡検知素子へ検知電流を流した時に生じる電圧降下量が、所定の閾値未満である場合には、地絡が生じているとみなして前記電力供給手段による電力供給を制限する制限手段(30)と、を備える電力供給装置。 - 前記地絡検知素子は、前記シャント抵抗の高電位側に直列接続されている請求項1に記載の電力供給装置。
- 前記地絡検知素子は、カソード側が低電位側に接続されたダイオード(D)である請求項1または2に記載の電力供給装置。
- 前記ダイオードと並列接続されたスイッチング素子(50)を備え、
前記負荷への電力供給時には前記スイッチング素子をオン作動させ、前記負荷への電力供給停止時には前記スイッチング素子をオフ作動させる制御手段(60)を備える請求項3に記載の電力供給装置。 - 前記地絡検知素子はスイッチング素子(50C)であり、
前記負荷への電力供給時には前記スイッチング素子をオン作動させ、前記負荷への電力供給停止時には電力供給時に比べて高インピーダンスの状態で前記スイッチング素子をオン作動させる制御手段(60C)を備える請求項1または2に記載の電力供給装置。 - 前記制御手段(60C)は、前記負荷に過大な電流が印加されているとみなした場合に、前記スイッチング素子をオフ作動させる請求項5に記載の電力供給装置。
- 前記地絡検知素子は、電界効果トランジスタ(50D)であり、
該電界効果トランジスタの寄生ダイオードのアノード側が前記負荷の側に位置するよう、前記電界効果トランジスタは接続されており、
前記負荷への電力供給時には前記電界効果トランジスタをオン作動させ、前記負荷への電力供給停止時には前記電界効果トランジスタをオフ作動させる制御手段(60D)を備える請求項1または2に記載の電力供給装置。 - 前記制限手段(30)は、前記負荷を作動させる要求が生じた場合に、前記電力供給手段から前記負荷への電力供給に先立ち前記電圧降下量を検出し、その検出した電圧降下量が前記閾値以上である場合に、前記電力供給手段による電力供給を許可する請求項1~7のいずれか1つに記載の電力供給装置。
- 前記地絡検知素子へ前記検知電流を出力する検知電流出力回路(31)を備える請求項8に記載の電力供給装置。
- 前記検知電流を、前記電力供給手段から前記負荷を通じて前記地絡検知素子へ出力する請求項8に記載の電力供給装置。
- 前記閾値を、前記負荷への電力供給時には停止時に比べて大きい値に変更する変更手段を備える請求項1~10のいずれか1つに記載の電力供給装置。
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CN201480008507.XA CN104995997B (zh) | 2013-02-12 | 2014-01-10 | 供电装置 |
DE112014000785.4T DE112014000785B4 (de) | 2013-02-12 | 2014-01-10 | Energieversorgungsvorrichtung |
US14/766,152 US9621024B2 (en) | 2013-02-12 | 2014-01-10 | Power supply device supplying limited DC power to load based on ground fault detection |
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JP2013024853A JP6051909B2 (ja) | 2013-02-12 | 2013-02-12 | 電力供給装置 |
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JP6613908B2 (ja) * | 2016-01-14 | 2019-12-04 | 株式会社オートネットワーク技術研究所 | 給電制御装置 |
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JP2014154448A (ja) | 2014-08-25 |
US9621024B2 (en) | 2017-04-11 |
CN104995997B (zh) | 2017-04-05 |
DE112014000785T5 (de) | 2015-10-22 |
CN104995997A (zh) | 2015-10-21 |
JP6051909B2 (ja) | 2016-12-27 |
US20150381030A1 (en) | 2015-12-31 |
DE112014000785B4 (de) | 2021-12-30 |
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