JP2015231269A - Backup power supply circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To discharge an electrical double layer capacitor used in a backup power supply circuit in a short time.SOLUTION: The backup power supply circuit includes: an electrical double layer capacitor that performs charging, receiving power supply from an external power supply and supplies electric power to a predetermined load upon abnormal shutdown of the external power supply; a booster circuit that boosts a voltage of electric power stored in the electrical double layer capacitor to a predetermined voltage and supplies the voltage to a load; and a discharge circuit that discharges electric power stored in the electrical double layer capacitor through the booster circuit upon normal shutdown of the external power supply.

Description

  The present invention relates to a backup power supply circuit.

  In recent years, computerization has progressed in various fields, and a backup power supply circuit that supplies an emergency power supply is used in preparation for the case where the power supply is cut off for some reason.

  For example, in an automobile, a controller (microcomputer) connected to a door lock switch in response to an operation of the door lock switch sends an instruction signal (control pulse signal) corresponding to a lock instruction or unlock instruction (unlock instruction). There is known a door lock control device that outputs and supplies power from a vehicle-mounted battery to a door lock motor to perform door lock and door lock release.

In such a door lock control device, when the vehicle battery is damaged or the power supply line is disconnected due to a vehicle collision or the like, the door lock is manually locked when power is not supplied from the vehicle battery. It becomes impossible to cancel.
In such a case, the backup power supply circuit supplies power instead of the vehicle-mounted battery to release the door lock.

JP 2014-33533 A

Conventionally, an electric double layer capacitor (EDLC) is known as a power storage device used in a backup power supply circuit.
An electric double layer capacitor is a capacitor that utilizes the physical phenomenon of an electric double layer, and has a large amount of stored electricity compared to its volume, and can be easily downsized.
Moreover, since internal resistance is low, rapid charge / discharge is possible.

By the way, if the electric double layer capacitor is left in a high voltage charged state, the electrolytic solution or electrode deteriorates, the internal resistance increases, and the effective charge capacity decreases. preferable.
Therefore, when mounted on a vehicle or the like, it is desirable to discharge at a key-off time.
Further, from the viewpoint of energy saving, it is desired that the controller for controlling the discharge by rapidly discharging the electric double layer capacitor also shuts off the power supply at an early stage.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a backup power supply circuit capable of performing discharge of an electric double layer capacitor used in the backup power supply circuit in a short time.

  In order to solve the above-described problem, the backup power supply circuit according to the embodiment is charged with power supplied from an external power supply, and an electric double layer capacitor that supplies power to a predetermined load when the external power supply is abnormally cut off, A booster circuit that boosts and outputs the voltage of the power stored in the multilayer capacitor to a predetermined voltage; a discharge circuit that discharges the power stored in the electric double layer capacitor via the booster circuit when the external power supply is normally shut off; Is provided.

  In the backup power supply circuit, the discharge circuit may cause the electric double layer capacitor to perform a constant power discharge.

  In the backup power supply circuit, a power supply switching circuit for connecting the booster circuit to the load, and a backflow prevention for disconnecting the external power supply from the load prior to connecting the booster circuit to the load by the power supply switching circuit. And a circuit.

  The backup power supply circuit may further include a step-down circuit that steps down the voltage of the external power source and outputs the voltage as a charging voltage to the electric double layer capacitor.

  The backup power supply circuit includes a controller that controls the entire backup power supply circuit, and a regulator that stabilizes the voltage of the drive power supplied to the controller, and the step-down circuit includes the regulator via the regulator. The voltage may be stepped down to a voltage in a voltage range suitable for supplying drive power.

The external power source is a battery mounted on the vehicle,
The load is a door lock device as an in-vehicle device,
The controller detects an abnormal interruption of the battery based on an output of an external collision detection sensor that detects a collision of the vehicle, and the electric power stored in the electric double layer capacitor is connected to the door lock via the booster circuit. You may make it supply to an apparatus.

  According to the backup power supply circuit of the embodiment, the electric power stored in the electric double layer capacitor is boosted via the booster circuit and discharged when the external power supply is normally cut off. There is an effect that the discharge can be continued and the discharge time can be shortened.

FIG. 1 is a schematic configuration block diagram of a backup power supply circuit. FIG. 2 is a schematic configuration diagram of the step-down circuit. FIG. 3 is a schematic configuration diagram of the booster circuit. FIG. 4 is an explanatory diagram of a specific example of the discharge circuit. FIG. 5 is an explanatory diagram of a specific example of the power supply switching circuit. FIG. 6 is an explanatory diagram of the configuration of the voltage dividing circuit.

Next, preferred embodiments will be described with reference to the drawings.
In the following description, as an example of a backup power supply circuit, when electric power supplied from an in-vehicle battery is stored, and electric power from the in-vehicle battery cannot be supplied due to disconnection of the power supply line at the time of a vehicle collision, etc. Next, a case will be described in which the present invention is applied to a backup power supply circuit that supplies power for unlocking (unlocking) to the door lock device instead of the vehicle-mounted battery.

FIG. 1 is a schematic configuration block diagram of a backup power supply circuit.
The backup power supply circuit 10 is connected to the in-vehicle battery BT and supplied with power from the in-vehicle battery BT. The battery monitor circuit detects the voltage at the battery connection terminal T1 and outputs a battery voltage detection signal VBT. 11, the voltage of the power supplied to the in-vehicle battery BT supplied from the ignition connection terminal T2 connected via the ignition switch IGsw and the ignition connection terminal T2 to the in-vehicle battery BT is reduced to a predetermined step-down voltage. Voltage output circuit 12 and an electric double layer capacitor (EDLC) 13 for storing the electric power stepped down by the voltage step-down circuit 12.

  Further, the backup power supply circuit 10 is supplied with the electric power of the in-vehicle battery BT supplied through the ignition connection terminal T2 or the stored electric power of the electric double layer capacitor 13, and outputs it while suppressing the voltage fluctuation of the supplied electric power. A controller that boosts the voltage of the power stored in the regulator 14 and the electric double layer capacitor 13 and supplies the boosted voltage to the door lock device DCLK as a load via the power supply terminal T11, and the controller that controls the entire backup power supply circuit 10 16 and a switching transistor that discharges the stored electric power of the electric double layer capacitor 13 at a constant power through the booster circuit 15 when the key is turned off (when the ignition switch IGsw is turned off) based on the discharge control signal Cdis output from the controller 16. Current limit connected in series It includes a discharge circuit 17 having an anti-a.

  Further, the backup power supply circuit 10 is connected to the power supply switching circuit 18 for connecting the electric double layer capacitor 13 to the power supply terminal T11 via the booster circuit 15 based on the switching control signal Csw output from the controller 16 and the controller 16 outputs. On the basis of the cutoff control signal Ccut, when the power switching circuit 18 connects the electric double layer capacitor 13 to the power supply terminal T11, the vehicle battery BT is electrically disconnected, and the vehicle power battery of the electric double layer capacitor 13 is stored. Based on the backflow prevention circuit 19 having a switch (switching transistor) for preventing backflow to the BT side and the drive control signal Cdrv output from the controller 16, the door lock device DLCK is connected to the door lock via the door lock control terminal T12. Outputs signal Sdl and door unlock signal Sudl. It includes a drive circuit 20, a to.

In the above configuration, the step-down circuit 12 is stepped down by the regulator 14 so as not to exceed the withstand voltage of the electric double layer capacitor 13 (for example, 6V). Moreover, the regulator 14 is outputting so that stable voltage (for example, 3V) can be provided with respect to a controller, even if the electrical storage voltage of the electric double layer capacitor 13 falls.
Furthermore, in the present embodiment, the collision detection sensor CDS is connected to the collision detection terminal T3 of the backup power supply circuit 10, and an external ground potential is connected to the ground terminal T4.

  The controller 16 is configured as a microcomputer including an MPU, a ROM, a RAM, and the like, and performs various controls in the backup power supply circuit 10 based on a control program stored in advance in the ROM.

FIG. 2 is a schematic configuration diagram of the step-down circuit.
The step-down circuit 12 can be broadly divided into a step-down chopper circuit 21 that steps down and outputs a voltage of power from the in-vehicle battery BT input via the ignition connection terminal T2, and a current of power output from the step-down chopper circuit 21. Based on the current detection resistor 22 for detection and the voltage across the current detection resistor 22, the current of the power output from the step-down chopper circuit 21 is detected, and the current detection signal IDET1 is fed to the step-down chopper circuit 21 as a feedback signal. An output current detection circuit 23; a backflow prevention diode 24; and a voltage division circuit 25 that performs voltage division to detect the voltage of the power output from the step-down chopper circuit 21 and outputs a voltage detection signal VDET1. ing.

  The step-down chopper circuit 21 is configured as a general step-down chopper circuit. As shown in FIG. 2, the step-down chopper circuit 21 is roughly divided into an input capacitor 30, a step-down controller 31, a diode 32, a coil 33, and an output capacitor 34. And.

  In the above configuration, the step-down controller 31 is built in based on the voltage of power from the in-vehicle battery BT input via the current detection signal IDET1, the voltage detection signal VDET1, and the detected ignition connection terminal T2 input as feedback signals. By controlling the switching of the switching transistor and intermittently outputting the power from the in-vehicle battery BT input through the ignition connection terminal T2, the voltage is stepped down to a predetermined voltage for charging the electric double layer capacitor 13. ing.

  The step-down controller 31 is configured as a switching regulator IC having a built-in MOS transistor.

FIG. 3 is a schematic configuration diagram of the booster circuit.
The booster circuit 15 is roughly divided into a boost chopper circuit 41 that boosts and outputs the voltage of the electric power from the electric double layer capacitor 13, and resistors R11 to R13. And a voltage dividing circuit 42 that performs voltage division to detect the voltage and outputs a voltage detection signal VDET2.

  The step-up chopper circuit 41 is configured as a general step-up chopper circuit. As shown in FIG. 3, the step-up chopper circuit 41 is roughly divided into an input capacitor 50, a step-up controller 51, a coil 52, a backflow prevention diode 53, and an output. A capacitor 54, a switching transistor 55, and a current limiting resistor 57 are provided.

  In the above configuration, the boost controller 51 performs switching based on the input voltage Vin that is the output voltage of the electric double layer capacitor 13, the current detection signal IDET2 that is input as a feedback signal, and the voltage detection signal VDET2 that is output from the voltage dividing circuit 42. The switching of the transistor 55 is controlled, and the output voltage of the electric double layer capacitor 13 is boosted to a predetermined constant voltage and output.

  The boost controller 51 is configured as a switching regulator IC.

FIG. 4 is an explanatory diagram of a specific example of the discharge circuit.
The discharge circuit 17 includes a current limiting resistor 61 that limits a discharge current when the electric double layer capacitor 13 is discharged via the booster circuit 15, a switching transistor 62 connected in series with the current limiting resistor 61, and an output from the controller 16. And a drive circuit 63 that drives the switching transistor 62 with the stored electric power of the electric double layer capacitor 13 based on the discharged control signal Cdis.

FIG. 5 is an explanatory diagram of a specific example of the power supply switching circuit.
The power supply switching circuit 18 includes a switch unit 71 composed of a pair of P-channel MOS transistors whose drain terminals are back-to-back connected, and a pair of NPN bipolar transistors. The power switching circuit 18 receives a switching control signal Csw input from the controller 16. Based on this, the pair of P-channel MOS transistors constituting the switch unit 71 are simultaneously turned on (closed), the booster circuit 15 is connected to the power supply terminal T11, and the electric power stored in the electric double layer capacitor 13 is loaded. And a switching drive unit 72 that can be supplied to the door lock device DLCK.

Next, the operation of the embodiment will be described.
In the following, three cases of (1) normal key switch on operation, (2) normal key switch off operation, and (3) abnormal operation will be described.

(1) Normal-time key switch-on operation First, the normal-time key switch-on operation will be described.
In this case, it is assumed that the electric double layer capacitor 13 stores electric power that can drive the controller 16 via the regulator 14.
The controller 16 of the backup power supply circuit 10 is in a normal state, that is, in a state in which power can be supplied from the in-vehicle battery BT (a state in which the voltage VBU is at a predetermined voltage level), Operates based on power.

  And in this state, the controller 16 is based on the battery voltage detection signal VBT output from the battery monitor circuit 11, and the voltage of the battery connection terminal T1, and hence the output voltage of the in-vehicle battery BT, is in the normal range (normal range). The switching control signal Csw for maintaining the set of NPN bipolar transistors constituting the switching drive unit 72 in the OFF state is output to the power supply switching circuit 18.

As a result, the pair of P-channel MOS transistors constituting the switch unit 71 are maintained in the off state (open state), and the electric double layer capacitor 13 is connected to the power supply terminal T11 via the booster circuit 15. There is no.
In parallel with the above operation, the controller 16 outputs a cutoff control signal Ccut for keeping the switch (switching transistor) constituting the backflow prevention circuit 19 in the closed state to the backflow prevention circuit 19.

As a result of the above operation, the electric power of the in-vehicle battery BT is supplied to the door lock device DLCK, which is a load, via the battery connection terminal T1, the backflow prevention circuit 19, the power supply switching circuit 18, and the power supply terminal T11.
Therefore, when an external control unit (not shown) outputs a door lock control signal to the door lock device DLC by operating the door lock / door lock release switch DSW, the door lock device DLCK locks or locks the door (not shown). Is released.

  On the other hand, since the ignition switch IGsw is in the on state (closed state), the electric power of the in-vehicle battery BT supplied via the ignition connection terminal T2 is supplied to the step-down circuit 12.

  The step-down controller 31 of the step-down circuit 12 receives a current detection signal IDET1 input from the current detection circuit 23 as a feedback signal, a voltage detection signal VDET1 input from the voltage dividing circuit 25, and the detected ignition connection terminal T2. Based on the voltage of the electric power from the in-vehicle battery BT, the switching frequency of the built-in switching transistor is controlled, and the electric power from the in-vehicle battery BT input via the ignition connection terminal T2 is intermittently output. The voltage is stepped down to a predetermined voltage for charging the multilayer capacitor 13 and output.

  As a result, the electric double layer capacitor 13 is charged (accumulated) to a predetermined voltage and is provided in the event of an abnormality.

(2) Normal Key Switch Off Operation Next, a normal key switch off operation will be described.
In this case, the electric double layer capacitor 13 is normally in a fully charged state.
As described above, when the electric double layer capacitor 13 is left in a charged state at a high voltage, the electrolytic solution or the electrode deteriorates, the internal resistance increases, and the effective charge capacity decreases. Is configured to discharge when the key switch is off.

  The controller 16 detects that the voltage applied via the ignition connection terminal T2 is equal to or lower than a predetermined voltage and the ignition switch IGsw is turned off.

As a result, when the output of the discharge control signal Cdis from the controller 16 to the discharge circuit 17 is interrupted, the drive circuit 63 of the discharge circuit 17 drives the switching transistor 62 with the stored electric power of the electric double layer capacitor 13 and is turned on (closed). State).
Accordingly, the stored electric power of the electric double layer capacitor 13 is discharged via the booster circuit 15. The discharge path at this time is the flow path of the current Idis shown in FIG.

  The booster controller 51 of the booster circuit 15 is based on the input voltage Vin, which is the output voltage of the electric double layer capacitor 13, the current detection signal IDET2 input as a feedback signal, and the voltage detection signal VDET2 output by the voltage divider circuit 42. The switching of the switching transistor 55 is controlled. As a result, the booster circuit 15 boosts the output voltage of the electric double layer capacitor 13 to a predetermined constant voltage (= a voltage equal to the drive voltage of the door lock device DLCK), and then outputs it to the discharge circuit 17 to discharge. To work.

  At this time, the boost controller 51 performs control so that the power consumed by the discharge circuit 17 is constant. Therefore, the discharge current is effectively reduced as the stored voltage of the electric double layer capacitor 13 decreases with discharge. It will be controlled to increase. The current detection signal IDET2 is used for detecting an overcurrent.

As described above, in the present embodiment, the electric storage voltage of the electric double layer capacitor 13 is boosted, and constant power discharge is performed to discharge at a constant power. As the amount of stored power decreases and the stored voltage decreases, the discharge current increases and the discharge time can be shortened.
Furthermore, since the current can be discharged by a current limiting resistor and driver having a smaller rated current compared to the constant resistance discharge, the cost can be reduced and the size can be reduced.

  Further, since constant power discharge is performed, the lower the voltage of the electric double layer capacitor 13 is, the faster the electric double layer capacitor 13 is discharged, and the discharge time can be shortened. The controller can be shifted to the stop state (sleep state) more quickly, and the power consumption can be reduced.

(3) Operation at the time of abnormality Next, in the event of an abnormality such as a vehicle collision, the operation when the in-vehicle battery BT is damaged, the power supply path wiring is disconnected, or the power supply from the in-vehicle battery BT is interrupted. explain.
In this case, the electric double layer capacitor 13 is assumed to be fully charged in the initial state.

  In the following description, it is assumed that a collision is detected by the collision detection sensor CDS, and a collision detection signal Scds is input to the controller 16 of the backup power supply circuit 10 via the collision detection terminal T3.

  By the way, the controller 16 is input from the battery monitor circuit 11 on the assumption that the collision detection signal Scds is not always correctly input even if it is detected that the collision detection signal Scds is input. Based on the battery voltage detection signal VBT, it is determined whether or not a normal voltage is supplied to the battery connection terminal T1.

  Based on the battery voltage detection signal VBT, the controller 16 performs control so that backup power is not supplied when a normal voltage is supplied to the battery connection terminal T1.

  On the other hand, the controller 16 of the backup power supply circuit 10 is based on the battery voltage detection signal VBT when the normal voltage is not supplied to the battery connection terminal T1 (when the low voltage power is supplied or not supplied at all). Control is performed so as to supply the backup power.

By the way, in order for the controller 16 to operate normally, a power source is required.
Therefore, in this embodiment, when the normal voltage is not supplied to the battery connection terminal T1, the regulator 14 suppresses the voltage fluctuation of the stored electric power of the electric double layer capacitor 13 and supplies the driving power of the controller 16 doing.

  First, the controller 16 outputs a cutoff control signal Ccut to the backflow prevention circuit 19 to turn off the backflow prevention circuit 19 (open state), and the power switching circuit 18 and thus the electric double layer capacitor 13 are electrically connected from the in-vehicle battery BT. Separate.

Thereafter, the controller 16 connects the electric double layer capacitor 13 and the booster circuit 15 to the power supply terminal T11 by the power supply switching circuit 18.
As a result, the stored electric power of the electric double layer capacitor 13 is supplied to the door lock device DCLK which is a load via the booster circuit 15 and the power supply switching circuit 18. The power supply path at this time is the flow path of the current Iegg shown in FIG.

  The booster controller 51 of the booster circuit 15 is based on the input voltage Vin, which is the output voltage of the electric double layer capacitor 13, the current detection signal IDET2 input as a feedback signal, and the voltage detection signal VDET2 output by the voltage divider circuit 42. The switching of the switching transistor 55 is controlled. As a result, the booster circuit 15 functions to boost the output voltage of the electric double layer capacitor 13 to a predetermined constant voltage (= a voltage equal to the drive voltage of the door lock device DLCK) and then supply it to the door lock device DLCK. .

Therefore, when the collision detection signal Scds is input and a normal voltage is not supplied to the battery connection terminal T1, the controller 16 locks the door lock after a certain time has elapsed since the collision detection signal Scds was input. A drive control signal Cdrv corresponding to the release operation is output to the drive circuit 20.
Then, the drive circuit 20 outputs a door lock release signal Sudl to the door lock device DLCK based on the drive control signal Cdrv.

  As a result, the door lock device DLCK is released even though power is not supplied from the in-vehicle battery BT.

  As described above, according to the present embodiment, even when power is not supplied from the in-vehicle battery BT due to a collision or the like, the door lock device DLCK is operated by the stored electric power of the electric double layer capacitor 13, The door lock can be released.

  Here, the backup power supply circuit is not limited to the above-described embodiments, and various modifications can be made within the scope described in the claims.

  In the above description, in the booster circuit 15, the boosted voltage is the same when discharging using the discharge circuit 17 and when supplying power to the door lock device DLCK at the time of abnormality. By setting the voltage higher than the boosted voltage at the time of power supply to the door lock device DLCK, it is possible to perform the discharge in a shorter time and to further reduce the power consumption of the controller 16.

FIG. 6 is an explanatory diagram of the configuration of the voltage dividing circuit.
In FIG. 6, the same parts as those in the embodiment of FIG.
6 is different from the embodiment of FIG. 3 in that a resistor R21 and a resistor R22 are provided in parallel with the resistors R11 and R12 constituting the voltage divider circuit 42 as a voltage divider circuit 42A instead of the voltage divider circuit 42. The changeover switch 81 is provided between the resistor R12 and the resistor R22 and the resistor R13 based on the switch control signal CSW1 from the controller 16.

In this case, the relationship among the resistance values of the resistor R11, the resistor R12, the resistor R21, and the resistor R22 is as follows.
Resistance R11 + resistance R12 <resistance R21 + resistance R22

Further, the controller 16 outputs a switching control signal CSW1 so as to switch to the resistance R21 and resistance R22 side during discharging through the discharging circuit 17.
In other words, the boosting factor in the boosting circuit 15 is set higher than the boosting factor at the time of abnormality during discharging.
As a result, the booster circuit 15 boosts the voltage to a higher voltage and performs constant power discharge at a higher voltage when the resistor R21 and the resistor R22 are connected, so that the discharge can be completed in a shorter time. .

  In the above description, the case where the in-vehicle battery BT is used as the external power source and the door lock device DLCK is used as the load has been described. However, an external power source (commercial power source, external battery, etc.) other than the in-vehicle battery BT is used. It is also possible to use a load (not limited to an on-vehicle device) other than the lock device DLCK.

DESCRIPTION OF SYMBOLS 10 Backup power supply circuit 11 Battery monitor circuit 12 Step-down circuit 13 Electric double layer capacitor 14 Regulator 15 Booster circuit 16 Controller 17 Discharge circuit 18 Power supply switching circuit 19 Backflow prevention circuit 20 Drive circuit 21 Step-down chopper circuit 22 Current detection resistor 23 Current detection circuit 24 backflow prevention diode 25 voltage dividing circuit 31 step-down controller 32 diode 33 coil 34 capacitor 41 step-up chopper circuit 42, 42A voltage division circuit 51 step-up controller 52 coil 53 backflow prevention diode 54 capacitor 55 switching transistor 57 current limiting resistor 61 current limiting resistor 62 Switching transistor 63 Drive circuit 71 Switch part 72 Switching drive part 81 Changeover switch BT Car battery CDS Collision detection sensor Sa Ccut shutoff control signal Cdis discharge control signal Cdrv drive control signal Csw, CSW1 switching control signal DLCK door lock device DSW door lock / door unlock switch IGsw ignition switch R11, R12, R13 resistor (voltage divider circuit)
R21, R22 resistance (voltage divider)
Scds Collision detection signal Sdl Door lock signal Sudl Door lock release signal

Claims (6)

An electric double layer capacitor that receives power from an external power supply and performs charging, and supplies power to a predetermined load when the external power supply is abnormally shut off;
A booster circuit that boosts and outputs a voltage of power stored in the electric double layer capacitor to a predetermined voltage;
A discharge circuit that discharges the electric power stored in the electric double layer capacitor through the booster circuit when the external power supply is normally shut off;
Backup power supply circuit with The discharge circuit causes the electric double layer capacitor to perform a constant power discharge through the booster circuit.
The backup power supply circuit according to claim 1. A power supply switching circuit for connecting the booster circuit to the load;
Prior to connecting the booster circuit to the load by the power supply switching circuit, a backflow prevention circuit that disconnects the external power supply from the load;
The backup power supply circuit according to claim 1, further comprising: A step-down circuit that steps down the voltage of the external power supply and outputs the electric double layer capacitor as a charging voltage is provided.
The backup power supply circuit according to any one of claims 1 to 3. A controller that controls the entire backup power supply circuit;
A regulator for stabilizing the voltage of the driving power supplied to the controller,
The step-down circuit steps down to a voltage in a voltage range suitable for supplying drive power to the controller via the regulator;
The backup power supply circuit according to claim 4. The external power source is a battery mounted on the vehicle,
The load is a door lock device as an in-vehicle device,
The controller detects an abnormal interruption of the battery based on an output of an external collision detection sensor that detects a collision of the vehicle, and the electric power stored in the electric double layer capacitor is connected to the door lock via the booster circuit. Let the equipment supply,
The backup power supply circuit according to claim 5.

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