JP7680713B2 - power supply - Google Patents

Description

An embodiment of the present invention relates to a power supply device including a power conversion circuit having a switching transformer.

Conventionally, there are emergency lights and emergency lights as lighting devices for displaying directions to evacuation routes, etc. In emergency lights, when an external power source such as a commercial AC power source is input, the power from the external power source is used to light a load such as an LED and charge a secondary battery, and when the external power source is cut off due to a power outage, that is, in an emergency when the external power source is not input, the emergency light source is turned on by the power from the charged secondary battery. Such power supply devices are generally designed to consume less than 3W of power. On the other hand, in the input current harmonic standard for lighting fixtures, when multiple power supply units are wired together in the same fixture, if the power consumption of the power supply unit is 2W or less, it is determined that the equipment consumes sufficiently little power that harmonic current measurement is not required. In this way, reducing power consumption is advantageous for the application of the above harmonic standard, so low power consumption is desirable.

JP 2009-54509 A

The problem that this invention aims to solve is to provide a power supply device that can reduce power consumption.

A power supply device according to an embodiment includes a first power conversion circuit, a charging circuit, a control unit, and a second power conversion circuit. The first power conversion circuit has a switching transformer and receives an input voltage. The charging circuit charges a storage battery from one secondary winding of the switching transformer. The control unit obtains power from another secondary winding different from the one secondary winding of the switching transformer when the input voltage is input. The operation of the second power conversion circuit is controlled by the control unit . The control unit intermittently controls charging of the storage battery in the charging circuit so that power consumption is 2 W or less .

The power supply device of the embodiment is expected to reduce losses in the control unit and reduce power consumption.

1 is a circuit diagram of a power supply device according to an embodiment;

An embodiment will be described below with reference to the drawings.

In FIG. 1, 1 is a lighting device. In this embodiment, the lighting device 1 will be described using an emergency light as an example. In the lighting device 1, a light source module 4, which is a load module equipped with a light source 3 as a load, can be detachably attached to a power supply device 2. As the light source 3, a light bulb or a light-emitting element can be used, but in this embodiment, for example, an LED is used as a light-emitting element that is a solid-state light source, and these light sources 3 are electrically connected in series, for example. Note that instead of an LED, an organic EL element or an inorganic EL element may be used as the light source 3.

The power supply device 2 comprises a first power conversion circuit 5 which is a power conversion circuit, a storage battery, i.e. a secondary battery (battery) 6 which is a backup power source, a charging circuit 7 which charges the secondary battery 6, and a second power conversion circuit 8 which is a power conversion circuit. The secondary battery 6 is a rechargeable battery pack in which multiple DC power sources are electrically connected in series, and has a capacity which allows the light source 3 to be kept lit with a predetermined luminous flux for a predetermined period of time or more when the input voltage 9 which is an external power source such as a commercial AC power source is cut off. For example, a nickel-metal hydride battery is used as the secondary battery 6. The secondary battery 6 has one or more cells.

In the lighting device 1, when the input voltage 9 is being input at all times, the power supply device 2 uses the input voltage 9 as a power source, and charges the secondary battery 6 through the charging circuit 7 with the output from the first power conversion circuit 5, which converts the voltage of the input voltage 9, and converts the output from the first power conversion circuit 5 through the second power conversion circuit 8 and supplies it to the light source 3 to light it up. In an emergency or power outage (cutoff), when the input voltage 9 is not being input, the lighting device 1 uses the secondary battery 6 as a power source, and converts the output from the secondary battery 6 through the second power conversion circuit 8 and supplies it to the light source 3 to light it up, thereby accurately informing people of the location of the emergency exit and the evacuation direction and providing guidance. The lighting device 1 is installed, for example, by attaching it to an installation surface such as a ceiling surface or a vertical wall surface, or by embedding it in the floor surface.

The first power conversion circuit 5 has the input voltage 9 as its input side and the charging circuit 7, i.e., the secondary battery 6, as its output side. In this embodiment, the input voltage 9 is an AC voltage, and the first power conversion circuit 5 receives the voltage obtained by rectifying the input voltage 9, which is an AC voltage. When the input voltage 9 is input, the first power conversion circuit 5 performs constant current control, constant voltage control, or constant power control on the input AC voltage. The first power conversion circuit 5 is electrically connected to the input voltage 9 via a noise prevention circuit 11, which is a filter circuit that removes noise from the input voltage 9 side, a primary side rectification means 12, which is a rectification means that rectifies the AC voltage from the input voltage 9, and a primary side smoothing means 13, which is a smoothing means that smoothes the output of the primary side rectification means 12. In other words, a DC voltage is input to the first power conversion circuit 5. The noise prevention circuit 11 includes, for example, a varistor and a capacitor electrically connected between the power supply lines, and a common mode choke coil, although not shown. The primary side rectification means 12 is electrically connected to the output side of the noise prevention circuit 11. A full-wave rectification means such as a diode bridge is used as the primary side rectification means 12. A primary side smoothing means 13 is electrically connected to the output side of the primary side rectification means 12. A smoothing element such as an electrolytic capacitor is used as the primary side smoothing means 13.

In addition, the first power conversion circuit 5 insulates the secondary battery 6 side from the input voltage 9 side. Since the lighting device 1 charges the secondary battery 6, it is preferable that the first power conversion circuit 5 is insulated from the input voltage 9 in consideration of safety. In this embodiment, the first power conversion circuit 5 is an isolated flyback converter. In addition, the first power conversion circuit 5 is a switching circuit having at least one switch means, and converts the input voltage 9 by the switching operation of the switch means. The first power conversion circuit 5 includes a switching transformer 15, and a switch means 16 is electrically connected to a primary winding 15a of the switching transformer 15, and a first rectifying means 17, which is a rectifying means, is electrically connected to a first secondary winding 15b1 of the switching transformer 15. A half-wave rectifying element such as a diode is used for the first rectifying means 17. And, a first smoothing means 18, which is a smoothing means, and a charging circuit 7 are electrically connected to the output side of the first secondary winding 15b1 of the first power conversion circuit 5, i.e., the first rectifying means 17. The primary winding 15a of the switching transformer 15 is electrically connected to the output side of the primary side smoothing means 13, and a secondary winding 15b1 set to a predetermined turn ratio with respect to the primary winding 15a is electrically connected to the charging circuit 7. In this embodiment, the first power conversion circuit 5 steps down the received voltage and outputs it by the switching transformer 15. The switch means 16 is, for example, an IPD circuit or the like. The switching of the switch means 16 is controlled by a first control unit (not shown) which is a control unit. The first control unit is connected in an insulated state to the secondary winding 15b1 of the switching transformer 15 using a photocoupler or the like. In this embodiment, the first control unit is, for example, electrically connected to a detection circuit that feeds back the electrical characteristics of the secondary side of the switching transformer 15, and controls the switching of the switch means 16 so that the output voltage of the first power conversion circuit 5 becomes a predetermined constant voltage.

The first smoothing means 18 is a smoothing element such as an electrolytic capacitor. The first smoothing means 18, the charging circuit 7, and the second power conversion circuit 8 are electrically connected to the cathode side of the first rectifying means 17.

The charging circuit 7 is a circuit that charges the secondary battery 6 from one secondary winding 15b1 of the switching transformer 15. The charging circuit 7 is configured, for example, by electrically connecting a resistor, which is a current setting means for setting the charging current of the secondary battery 6, and the secondary battery 6 in series. The charging circuit 7 is a constant current circuit that charges the secondary battery 6 with a constant current by the charging current set by the resistor. In addition, a first switch, which is a switching means, is electrically connected to the connection point between the resistor and the secondary battery 6 in the charging circuit 7. In addition, a second switch, which is a switching means, is electrically connected in parallel to the resistor and the first switch. The second switch is electrically connected to the connection point between the first switch and the secondary battery 6. The first switch is turned on when the input voltage 9 is input, and the second switch is turned on when the input voltage 9 is not input, that is, when the secondary battery 6 is discharged. In other words, the first switch and the second switch constitute a selection means that is selectively switched depending on whether the input voltage 9 is input or not. The first switch is a means for disconnecting the secondary battery 6 from the charging circuit 7. The charging circuit 7, the first switch, and the second switch form a charging/discharging circuit.

In this embodiment, the second power conversion circuit 8 is electrically connected to the output side of the first power conversion circuit 5. The second power conversion circuit 8 has a charging circuit 7, i.e., a secondary battery 6, on the input side. In the illustrated example, the second power conversion circuit 8 acts as a lighting circuit (a constant lighting circuit and an emergency lighting circuit) that supplies power to the light source 3 regardless of whether the input voltage 9 is input or not. The second power conversion circuit 8 is a discharge circuit that includes at least one switching element 20 and converts the input voltage by the switching operation of the switching element 20. In this embodiment, the voltage of the secondary battery 6 is set lower than the forward voltage of the light source 3 (the voltage obtained by adding up the forward voltages of the individual light sources 3), so the second power conversion circuit 8 is a boost circuit. As an example of the boost circuit, a boost chopper circuit is used in this embodiment. That is, in the second power conversion circuit 8, a series circuit of an inductor 21 and a switching element 20 is electrically connected to the output side of one first smoothing means 18, and a second rectification means 22, which is a rectification means, is electrically connected in parallel to the switching element 20. The second rectifier 22 is a half-wave rectifier such as a diode. The light source module 4 is electrically connected to the output side of the second power conversion circuit 8 via the second smoothing means 24, which is a smoothing means. The second smoothing means 24 is a smoothing element such as an electrolytic capacitor.

The switching of the switching element 20 is controlled by the second control unit 25, which is a control unit. The second control unit 25 controls the switching of the switching element 20 according to the current flowing through the light source 3, regardless of whether the input voltage 9 is being input or not. For example, the second control unit 25 switches the switching element 20 at a predetermined switching frequency. The switching frequency is set to, for example, 250 kHz. The second control unit 25 also controls the charging and discharging of the secondary battery 6 by the charging circuit 7 by switching the first switch and the second switch on and off depending on whether the input voltage 9 is present. The switching element 20 is, for example, a FET.

The second control unit 25 generates power from the power obtained from the output side of the first power conversion circuit 5, i.e., the other secondary winding 15b2 of the switching transformer 15, the secondary battery 6, and the output side of the second power conversion circuit 8, by the power supply regulator 26. That is, when the input voltage 9 is input, the second control unit 25 obtains power from the first power conversion circuit 5 via the other secondary winding 15b2, and when the input voltage 9 is not input, obtains power from the secondary battery 6 or the second power conversion circuit 8. The power supply regulator 26 is electrically connected to the other secondary winding 15b2 of the first power conversion circuit 5, the secondary battery 6, and the output side of the second power conversion circuit 8, respectively, via protection means 27, 28, and 29. A three-terminal regulator or the like is used as the power supply regulator 26. Protection elements such as diodes are used as the protection means 27, 28, and 29.

Here, the other secondary winding 15b2 of the switching transformer 15 is a secondary winding dedicated to powering the second control unit 25. The other secondary winding 15b2 is set to a predetermined other winding ratio different from the predetermined one winding ratio with respect to the primary winding 15a. The winding ratio of the other secondary winding 15b2 is set to be smaller than the winding ratio of the one secondary winding 15b1, so that the output voltage is smaller than that of the one secondary winding 15b1. The winding ratio of the other secondary winding 15b2 is determined according to the power supply voltage of the second control unit 25 that is set in advance. The output voltage from the other secondary winding 15b2 is set to a voltage close to the power supply voltage of the second control unit 25 and lower than the voltage of the secondary battery 6. The other secondary winding 15b2 is electrically connected to the other first rectifying means 31, which is a rectifying means. A half-wave rectifying element such as a diode is used as the other first rectifying means 31. The output side of the other secondary winding 15b2 of the first power conversion circuit 5, i.e., the other first rectification means 31, is electrically connected to the other first smoothing means 32, which is a smoothing means.

The other first smoothing means 32 is a smoothing element such as an electrolytic capacitor. The power supply regulator 26 is electrically connected to the cathode side of the other first rectifying means 31 via the other first smoothing means 32 and the protection means 27.

And, in the above-mentioned lighting device 1, when the input voltage 9 is input, that is, always, in other words, when the lighting device 1 is operated by the input voltage 9, in the power supply device 2, the first switch is turned on and the second switch is turned off by the second control unit 25 that takes power from the other secondary winding 15b2 of the switching transformer 15 of the first power conversion circuit 5 via the power regulator 26, and in the first power conversion circuit 5, the first control unit switches the switch means 16 so that the output voltage of the first power conversion circuit 5 becomes a predetermined constant voltage. In the charging circuit 7 whose operation is controlled by the second control unit 25, the secondary battery 6 is charged with a constant charging current set by a resistor. Also, in the second power conversion circuit 8 whose operation is controlled by the second control unit 25, the second control unit 25 detects the current flowing in the light source module 4, i.e., the light source 3, switches the switching element 20 so that this current is constant, and supplies power to the light source module 4, i.e., the light source 3, via the second rectification means 22 and the second smoothing means 24, to light the light source 3. As a result, the second power conversion circuit 8 acts as a boost chopper circuit. In this way, by keeping the current of the light source 3 constant, the output voltage of the second power conversion circuit 8 is controlled to be approximately constant as the forward voltage of the light source 3, which in this embodiment is the LED, and the second power conversion circuit 8 acts as a constant voltage source.

Thus, according to one embodiment, in a power supply device 2 for a lighting device 1 having a first power conversion circuit 5 having a switching transformer 15, the power supply for the second control unit 25 for controlling the second power conversion circuit 8 is taken from another secondary winding 15b2 different from one secondary winding 15b1 of the switching transformer 15 which serves as the power supply for the charging circuit 7 that charges the secondary battery 6. By bringing the voltage output from the other secondary winding 15b2 closer to the power supply voltage of the second control unit 25, it is possible to suppress losses in the power supply regulator 26 of the second control unit 25, and therefore to suppress power consumption.

The power supply regulator 26 is usually a three-terminal regulator, but the three-terminal regulator is a heat-generating component that generates more heat the greater the difference between the input voltage and the output voltage. Therefore, by bringing the input voltage from the other secondary winding 15b2 of the switching transformer 15 closer to the power supply voltage of the second control unit 25 as described above, heat generation in the power supply regulator 26 can be suppressed, and the temperature of the power supply device 2 can be reduced. As a result, the component placement and integration on the circuit board are less subject to restrictions due to heat generation, improving the degree of freedom in placement, which allows for higher density and smaller size.

In particular, in the case of a power supply device 2 in which the power supply voltage of the second control unit 25 is lower than the voltage of the secondary battery 6, in the conventional example in which the secondary winding of the switching transformer 15 is a single system and the power supply for charging the secondary battery 6 by the charging circuit 7 and the power supply for the second control unit 25 are taken, the voltage step-down in the power supply regulator 26 of the second control unit 25 becomes large, resulting in large losses. In contrast, in this embodiment, by setting another secondary winding 15b2 dedicated to taking the power supply voltage of the second control unit 25, it is possible to suppress losses in the second control unit 25.

When the input voltage 9 is constantly being input, the power consumption of the power supply device 2 is mainly the power required by the charging circuit 7 and its load, the secondary battery 6, but the power consumption of the second control unit 25 itself also accounts for a large proportion. Therefore, by suppressing the power consumption of the second control unit 25 as described above and making the power consumption of the power supply device 2 2 W or less, the power supply device 2 is considered to be a device that does not require measurement of harmonic current in the input current harmonic standard for lighting fixtures, which is advantageous in applying the harmonic standard when, for example, a lighting fixture is constructed by combining multiple power supply devices 2.

When the input voltage 9 is not being input, i.e., during an emergency, in other words, during a power outage, the first power conversion circuit 5 in the power supply device 2 does not operate, and the second control unit 25, which takes power from the secondary battery 6 via the power regulator 26, turns off the first switch and turns on the second switch, discharging the secondary battery 6 to the second power conversion circuit 8. In the second power conversion circuit 8, the second control unit 25 detects the current flowing through the light source module 4, i.e., the light source 3, switches the switching element 20 so that this current is constant, and supplies power to the light source module 4, i.e., the light source 3, via the second rectifier means 22 and the second smoothing means 24. As a result, the second power conversion circuit 8 acts as a boost chopper circuit.

In this way, when the input voltage 9 is not being input, the second control unit 25 obtains power from the voltage of the secondary battery 6 or the boosted voltage of the secondary battery 6. Even when the input voltage 9 is not being input and the output of the first power conversion circuit 5 cannot be secured, the second control unit 25 can continue to operate by obtaining power from the secondary battery 6.

In the above embodiment, the second control unit 25 may intermittently control the charging of the secondary battery 6 in the charging circuit 7 to reduce power consumption to 2 W or less.

The above power supply device 2 can also be applied in a similar manner when the lighting device 1 is an emergency light in which the second power conversion circuit 8 turns on the light source 3 only when the input voltage 9 is not being input.

Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims.

Reference Signs List 2 Power supply device 5 First power conversion circuit 6 Secondary battery as a storage battery 7 Charging circuit 8 Second power conversion circuit 9 Input voltage 15 Switching transformer 15b1 First secondary winding 15b2 Second secondary winding 25 Second control unit as a control unit

Claims (3)

a first power conversion circuit having a switching transformer and receiving an input voltage;
a charging circuit for charging a storage battery from one secondary winding of the switching transformer;
a control unit that obtains power from another secondary winding different from the one secondary winding of the switching transformer when the input voltage is input;
A second power conversion circuit whose operation is controlled by the control unit ;
The control unit controls charging of the storage battery in the charging circuit intermittently so that power consumption is 2 W or less.
A power supply device comprising: 2. The power supply device according to claim 1, wherein a power supply voltage of the control unit is lower than a voltage of the storage battery . 3. The power supply device according to claim 1, wherein the control unit obtains power from a voltage of the storage battery or a boosted voltage of the storage battery when the input voltage is not being input.

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