Power supply device

Abstract

Provided is a power supply device that has a capacity which does not change even after a long period of use, and that comprises an auxiliary power supply in which the occurrence of noise is prevented.　A power supply device 1 comprises: a main power supply unit 11 that is connected to a load 16; an auxiliary power supply unit 12 that has a smaller capacity than the main power supply unit 11; a switching means that is provided to a power supply path which connects the main power supply unit 11 and the auxiliary power supply unit 12; and a control means 15 that controls the switching means. The switching means is provided with an input switch 13 that is disposed between the main power supply unit 11 and the auxiliary power supply unit 12 and an output switch 14 that is disposed between the auxiliary power supply unit 12 and the load 16. The control means 15 controls the supply of power from the auxiliary power supply unit 12 to the load 16 by controlling opening and closing of the input switch 13 and the output switch 14.

Description

power supply

[0001] The present invention relates to a power supply device having a main power supply and an auxiliary power supply.

[0002] Power supply devices are known that supply power to a specified load from an auxiliary power supply when a malfunction occurs in a main power supply and its power supply line. Such power supply devices are installed in vehicles and various industrial equipment.

[0003] For example, in vehicles, automatic door lock release mechanisms are known that allow occupants to escape to the outside in the event of a vehicle collision. Automatic door lock operation requires a power supply, but if a malfunction occurs in the normal power supply system, the door locks will not operate automatically. Therefore, a backup power supply path is provided between the main power source and the automatic door lock release mechanism, or a power supply device equipped with an auxiliary power source as a backup power source is used.

[0004] Fig. 5 shows a conventional example of a power supply device that can supply power at a required voltage by using an electric double layer capacitor (EDLC) as an auxiliary power supply and further placing a step-up / step-down converter between the power supply and the load. The power supply device 100 in Fig. 5 uses an auxiliary power supply 102, which is an electric double layer capacitor, in addition to a main power supply 101, and supplies power at a specified voltage to a load 106. Switching between the power supply from the main power supply 101 and the auxiliary power supply 102 is performed by an input switch 103 and an output switch 104 controlled by control means 105. The power supplied from the auxiliary power supply 102 is adjusted to the required voltage by a step-up / step-down converter 108 and then supplied.

[0005] Furthermore, Patent Document 1 discloses a backup power supply device that includes a battery as a main power source, an electric double layer capacitor as an auxiliary power source, and a summing diode as a comparison control unit. The backup power supply device of Patent Document 1 discharges from the electric double layer capacitor when the battery is disconnected from the comparison control unit.

[0006] Japanese Patent Application Laid-Open No. 2020-124039

[0007] As shown in Figure 5, when a switching element such as a step-up / step-down converter is incorporated into the power supply from the auxiliary power supply, switching noise can cause noise in the audio equipment or malfunction. Therefore, power supply devices equipped with an auxiliary power supply require electromagnetic compatibility (EMC) measures. Furthermore, electric double-layer capacitors, which are widely used as a power storage device for auxiliary power supplies, change in capacitance with temperature and deteriorate at high temperatures, which can lead to a capacity shortage over long periods of use.

[0008] The present invention has been made in consideration of the above problems, and an object of the present invention is to provide a power supply device equipped with an auxiliary power supply whose capacity does not change even after long-term use and which prevents noise generation.

[0009] The present invention relates to a power supply device. The power supply device of the present invention comprises a main power supply connected to a load, an auxiliary power supply having a smaller capacity than the main power supply, switch means provided in a power supply path connecting the main power supply and the auxiliary power supply, and control means for controlling the switch means. The switch means of the power supply device of the present invention comprises an input switch disposed between the main power supply and the auxiliary power supply, and an output switch disposed between the auxiliary power supply and the load. The control means controls the opening and closing of the input switch and the output switch, thereby controlling the power supply from the auxiliary power supply to the load.

[0010] In the power supply device of the present invention, the auxiliary power supply unit preferably includes a secondary battery or a capacitor and supplies power at a voltage equivalent to the voltage required by the load.

[0011] The control means of the power supply device of the present invention preferably detects the voltage of the main power supply section supplied to the power supply path, and when the voltage of the main power supply section falls below a predetermined threshold, controls the output switch to close for a certain period of time and simultaneously controls the input switch to open for a certain period of time.

[0012] It is preferable that the control means of the power supply device of the present invention monitors the voltage of the load, and when the voltage of the load falls below a predetermined threshold, performs control to close the output switch for a certain period of time.

[0013] The power supply device of the present invention preferably further comprises an output switch-on determining means.

[0014] The means for determining whether to switch on the output of the power supply may include an external switch means.

[0015] The power supply device of the present invention does not use a step-up / step-down means in the auxiliary power supply section, thereby making it possible to suppress noise generation.

[0016] The power supply device of the present invention is configured with a secondary battery or a capacitor, so that the capacity does not change even at high temperatures and it can be used for a longer period of time than conventional devices.

[0017] FIG. 1 is a block diagram schematically showing the configuration of a power supply device according to a first embodiment. FIG. 2 is a block diagram schematically showing the configuration of a power supply device according to a second embodiment. FIG. 3 is a block diagram schematically showing the configuration of a power supply device according to a fourth embodiment. FIG. 4 is a block diagram schematically showing the configuration of a power supply device according to a fifth embodiment. FIG. 5 is a block diagram schematically showing a conventional example of a power supply device equipped with an auxiliary power supply unit.

[0018] A preferred embodiment of the power supply device of the present invention will be described below with reference to the drawings, taking as an example a case where the power supply device is used as a power supply device for a vehicle. Note that the following embodiment is merely an example of one aspect of the invention and is not intended to limit the scope of the claims.

[0019] 1 is a block diagram showing a schematic configuration example of a power supply device 1 according to a first embodiment. The power supply device 1 in this embodiment includes a main power supply unit 11, an auxiliary power supply unit 12, an input switch 13, an output switch 14, and control means 15. The power supply device 1 supplies power to a load 16.

[0020] When the vehicle is a gasoline-powered vehicle, the main power supply unit 11 is a vehicle battery used to supply power to a load 16, which is an electrical component. When the vehicle is a hybrid vehicle, the main power supply unit 11 is an auxiliary battery used to supply power to a hybrid system and the load 16, which is another electrical component.

[0021] A secondary battery such as a lead battery or a lithium ion battery, or a capacitor such as a lithium ion capacitor that can supply high voltage and has a larger capacity than conventional capacitors, can be used as the auxiliary power supply 12. The auxiliary power supply 12 has the same rated voltage as the voltage supplied to the load 16. As an example, the rated voltage of the auxiliary power supply is 13.5 V, and the maximum charging voltage is 15.0 V. As shown in FIG. 1 , the main power supply 11 and the auxiliary power supply 12 are directly connected by wiring.

[0022] The power supply device 1 includes a switch means and a control means for controlling the power supply from the auxiliary power supply unit 12 to the load 16. The switch means in this embodiment is made up of an input switch 13 and an output switch 14.

[0023] An input switch 13 is provided in the power supply path connecting the main power supply unit and the auxiliary power supply unit. In a preferred embodiment, the input switch 13 is configured by connecting two field effect transistors (FETs) 13a and 13b in series.

[0024] An output switch 14 is provided in the power supply path connecting the auxiliary power supply 12 and the load 16. The output switch 14 is also preferably a field effect transistor (FET).

[0025] The power supply device 1 includes a control means 15 that controls the input switch 13 and the output switch 14. The control means 15 controls the opening and closing of the input switch 13 and the output switch 14, thereby controlling the power supply from the auxiliary power supply unit 12 to the load 16.

[0026] The main components of the control means 15 of this embodiment and the contents of the controls that it can execute are described below. - It is electrically connected between the main power supply unit 11 and the source side of the input switch 13a, measures the voltage supplied from the main power supply unit 11, and monitors the power supply state of the main power supply unit 11 based on the voltage value. - It has a first gate driver, and controls the gate voltage of the input switches 13a and 13b. - It has a second gate driver, and controls the gate voltage of the output switch 14.

[0027] During normal operation when the voltage of the main power supply unit 11 is maintained at a predetermined value, the main power supply unit 11 supplies power to the load 16 via a separate power supply path not shown in Fig. 1. During normal operation, the control means 15 keeps the input switch 13 normally closed and the output switch 14 normally closed. As a result, the auxiliary power supply unit 12 is continuously charged by the main power supply unit 11 and a generator not shown.

[0028] When the control means 15 detects that the voltage of the main power supply unit 11 has fallen below a predetermined voltage, it opens the input switch 13 and closes the output switch 14, thereby supplying power from the auxiliary power supply unit 12 to the load 16. In a more preferred embodiment, the control means 15 limits the time during which power is supplied from the auxiliary power supply unit 12 to the load 16 to a certain period of time.

[0029] The control means 15 of this embodiment starts supplying power from the auxiliary power supply unit 12 to the load even if the supply voltage of the main power supply unit 11 drops due to a temporary malfunction of the main power supply unit 11 or during replacement work of the main power supply unit 11. Therefore, there is a possibility that the auxiliary power supply unit 12 will supply power to the load even though it is not actually necessary. The control means 15 limits the power supply from the auxiliary power supply unit 12 to a certain period of time, thereby suppressing such unnecessary consumption of power from the auxiliary power supply unit 12 and, as a result, extending the useful life of the auxiliary power supply unit 12.

[0030] Furthermore, the input switch 13 of this embodiment is configured by connecting two field effect transistors (FETs) 13a and 13b in series, which prevents the input switch 13 from being destroyed by a momentary large current flowing through it when the auxiliary power supply 12 has a lower voltage than the main power supply 11 and the auxiliary power supply 12 is shorted.

[0031] Second Embodiment Fig. 2 shows a power supply device 2 according to a second embodiment of the present invention when used as a power supply device for a vehicle. Components having the same configuration as those in power supply device 1 are designated by the same reference numerals and will not be described again.

[0032] The power supply device 2 further includes an output switch-on determination means in addition to the configuration of the power supply device 1. The output switch-on determination means of this embodiment includes a transistor 18 and a wiring 19 connecting the transistor 18 and the control means 25. The output switch-on determination means of this embodiment controls the base side of the transistor 18, and inputs a signal to the control means 25 to determine whether the output switch is to be turned on or off.

[0033] The output switch-on determining means may be a high or low input to the power supply.

[0034] The output switch-on determination means may be a component within the power supply device, or may be an external switch means that controls the input on the base side of a transistor. For example, as the output switch-on determination means for an automatic release mechanism of a vehicle door lock, the output switch-on determination means may be a load supplied with power from the power supply device, a collision detection device, an emergency call (vehicle emergency notification system), a driver monitoring (automatic driver abnormality detection system), an airbag, or a seatbelt pretensioner.

[0035] In the power supply device 2 shown in FIG. 2, the output switch 14 is pulled up from the auxiliary power supply unit 12, and the output switch 14 is turned on by dropping it to ground voltage on the operating side, thereby realizing an output switch 14 that is inexpensive and resistant to noise.

[0036] The control means 25 of this embodiment can start supplying power from the auxiliary power supply unit 12 not only when the voltage of the main power supply unit 11 falls below a predetermined value, but also when it receives an input from the output switch-on determination means to turn on the output switch 14. By using both the state of the main power supply unit 11 and the input from the output switch-on determination means to determine whether to supply power from the auxiliary power supply unit 12, power supply from the auxiliary power supply unit 12 to the load 16 can be performed with greater accuracy. As a result, the number of times power is supplied from the auxiliary power supply unit 12 can be reduced, and the useful life of the auxiliary power supply unit 12 can be extended.

[0037] In a more preferred embodiment, the control means 25 can limit the time during which power is supplied from the auxiliary power supply unit 12 to the load 16 to a certain period, as in the first embodiment. This can further extend the service life of the auxiliary power supply unit 12.

[0038] Third Embodiment In the third embodiment, a different control method is applied to the same power supply device 2 as in the second embodiment. In this embodiment, when the control means 25 receives an input from the output switch-on determination means to turn on the output switch 14, it performs control to start supplying power from the auxiliary power supply unit 12 to the load 16, even if the voltage of the main power supply unit 11 is normal. This type of control has the unique effect of improving the ability to respond to abnormalities.

[0039] In the present embodiment, it is preferable that the control means 25 limits the power supply time to a certain period when starting power supply from the auxiliary power supply unit 12 to the load 16. This is because it is expected that the frequency of power supply from the auxiliary power supply unit 12 will increase if an abnormality in the voltage of the main power supply unit 11 is not taken into account when turning on the output switch 14.

[0040] The control method of this embodiment has the unique effect of being able to handle not only abnormal situations but also various types of fault diagnosis.

[0041] 3 shows a power supply device 3 according to a fourth embodiment of the present invention when used as a power supply device for a vehicle. Components having the same configuration as those in power supply device 1 are designated by the same reference numerals and redundant explanations will be omitted.

[0042] 3 includes, in addition to the components of the power supply 1, a control means 35 and wiring 21 that electrically connects the main power supply unit 11 and the load 16. The control means 35 monitors the voltage of the load 16. When the voltage of the load 16 falls below a predetermined threshold, the control means 35 turns on (closes) the output switch 14 for a certain period of time.

[0043] Here, the voltage drop of the load 16 may be caused not only by a decrease in the amount of power supplied to the load 16, but also by a short circuit in the power supply path from the main power supply unit 11 to the load 16. Therefore, the control means 35 may have a function of opening the output switch 14 when it is determined that the power supply path to the load 16 is short circuited.

[0044] 4 shows a power supply device 4 according to a fifth embodiment of the present invention when used as a power supply device for a vehicle. Components having the same configuration as those in power supply device 2 are designated by the same reference numerals and redundant explanations will be omitted.

[0045] In addition to the configuration of the power supply device 2, the power supply device 4 includes a control means 45 and wiring 21 that electrically connects the main power supply unit 11 and the load 16. The control means 45 monitors the voltage of the load 16. When the voltage of the load 16 falls below a predetermined threshold, the control means 45 turns on (closes) the output switch 14 for a certain period of time.

[0046] As in the fourth embodiment, the voltage drop at the load 16 may be caused not only by a decrease in the amount of power supplied to the load 16, but also by a short circuit in the power supply path from the main power supply unit 11 to the load 16. Therefore, the control means 15 may have a function of opening the output switch 14 when it is determined that the power supply path to the load 16 is short circuited.

[0047] Although the power supply device of the present invention has been described above in terms of the first to fifth embodiments, the configuration of the power supply device can be modified as appropriate. For example, any switching elements can be used as the input switch and output switch. Furthermore, the configuration of the main power supply unit and auxiliary power supply unit can be modified as appropriate to suit the type of load to which power is supplied.

[0048] The vehicle power supply device according to the present invention can be mounted in any industrial or domestic equipment, as well as in vehicles.

[0049] 1,100 Vehicle 11,101 Main power supply unit 12,102 Auxiliary power supply unit 13,103 Input switch 14,104 Output switch 15,25,35,45,105 Control means 16,106 Load 17,107 Generator 18 Transistor 19,21,22 Wiring

Claims

1. A power supply device comprising a main power supply unit connected to a load, an auxiliary power supply unit having a smaller capacity than the main power supply unit, switch means provided in a power supply path connecting the main power supply unit and the auxiliary power supply unit, and control means for controlling the switch means, wherein the switch means includes an input switch disposed between the main power supply unit and the auxiliary power supply unit, and an output switch disposed between the auxiliary power supply unit and the load, and the control means controls the feeding of power from the auxiliary power supply unit to the load by controlling the opening and closing of the input switch and the output switch.

2. The power supply device according to claim 1, wherein the auxiliary power supply unit includes a secondary battery or a capacitor and supplies power at a voltage equivalent to the required voltage of the load.

3. The power supply device according to claim 1, wherein the control means detects the voltage of the main power supply unit supplied to the power supply path, and when the voltage of the main power supply unit becomes equal to or lower than a predetermined threshold value, controls the output switch to be closed for a certain period of time and simultaneously controls the input switch to be opened for a certain period of time.

4. The power supply device according to claim 1, wherein the control means monitors the voltage of the load, and when the voltage of the load becomes equal to or lower than a predetermined threshold value, controls the output switch to be closed for a certain period of time.

5. The power supply device according to claim 1, further comprising output switch on determination means.

6. The power supply device according to claim 4, wherein the output switch on determination means includes external switch means.

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