JP5988910B2 - Power supply - Google Patents

Description

  The present invention uses a switching transformer to connect a switching power supply circuit to the primary side of the switching transformer, and to connect a main output circuit and a sub output circuit to the secondary side of the switching power supply to stabilize the output by feedback control of the output. Relates to the device. This power supply device drives the first and second semiconductor light emitting elements (main light source and safety light) in a contradictory manner like an LED illumination power supply device with a safety light.

  Conventionally, the switching transformer for driving the first semiconductor light emitting element and the switching transformer for driving the second semiconductor light emitting element are configured separately. FIG. 8 shows a schematic configuration of a conventional power supply apparatus. In the power supply device shown in FIG. 8, the power from the AC power supply 10 is alternatively supplied to the main-side switching power supply circuit 31 and the sub-side switching power supply circuit 32 via the input line switching circuit 20. ing. The main-side switching power supply circuit 31 is connected to the primary winding of the main-side switching transformer 41, and the main output circuit 50 is connected to the secondary winding to drive the first semiconductor light emitting element 70. ing. On the other hand, the sub-side switching power supply circuit 32 is connected to the primary winding of the sub-side switching transformer 42, and the sub-output circuit 60 is connected to the secondary winding so as to drive the second semiconductor light emitting element 80. It has become. The output from the main output circuit 50 is fed back to the switching power supply circuit 31 on the main side, and the output of the main output circuit 50 is stabilized. Further, the output from the sub output circuit 60 is fed back to the switching power supply circuit 32 on the sub side, and the output of the sub output circuit 60 is stabilized. A typical example of the semiconductor light emitting elements 70 and 80 is an LED (light emitting diode).

  When the input line switching circuit 20 having a transfer type changeover switch is switched to the main side, the switching power supply circuit 31, the switching transformer 41, and the main output circuit 50 on the main side are activated, and the first semiconductor light emitting element 70 is turned on. The On the other hand, when the input line switching circuit 20 is switched to the sub side, the switching power supply circuit 32, the switching transformer 42, and the sub output circuit 60 on the sub side are activated, and the second semiconductor light emitting element 80 is turned on. These two states do not occur simultaneously, and only one of them is activated according to the state of the input line switching circuit 20. The switch in the input line switching circuit 20 is a transfer type switch, and the main-side switching power supply circuit 31 is connected to the normally closed contact portion, and the sub-side switching power supply circuit 32 is connected to the normally-open contact portion.

  In the switching power supply circuits 31 and 32, conversion of AC voltage to DC voltage, step-down of DC voltage, and switching of DC current are performed, and the obtained switching current is supplied to the main output circuit via the switching transformers 41 and 42. 50 or the sub output circuit 60. The switching power supply circuits 31 and 32 each include a rectifier circuit, a step-down circuit, and a converter circuit. Since it has two converter circuits, a converter circuit of the switching power supply circuit 31 on the main side and a converter circuit of the switching power supply circuit 32 on the sub side, it is called a two converter system. The switching transformer is called a two-transformer system because it has two transformers, a main-side switching transformer 41 and a sub-side switching transformer 42.

  As an application example of such a power supply device, there is a power supply device for LED illumination with a safety light. That is, a relatively large power LED (light emitting diode) is applied as the first semiconductor light emitting element 70, and a relatively small power LED is applied as the second semiconductor light emitting element 80. The former is used for normal lighting, and the latter is used as a security light during a power failure.

JP-A-11-285245 JP 2006-31650 A JP 2012-44758 A

  In the case of the conventional example described above, the switching transformers (41, 42) must be associated with the main output circuit 50 and the sub output circuit 60 because of the two-converter configuration. That is, two switching transformers must be prepared as drive sources for both output circuits. As a result, the circuit configuration becomes complicated and the product cost increases.

  The present invention has been made in view of the above, and an object of the present invention is to provide a power supply apparatus capable of realizing a simplified circuit configuration as compared with the conventional two-transformer system, in order to reduce the product cost.

  A power supply device according to the present invention is connected to a switching power supply circuit, a switching transformer having a primary winding connected to the output side of the switching power supply circuit, and first and second secondary windings of the switching transformer. A main output circuit and a sub output circuit. The main output circuit is connected to the first secondary winding of the switching transformer and outputs to the first semiconductor light emitting element. The sub-output circuit is connected to the second secondary winding of the switching transformer and outputs to the second semiconductor light emitting element.

  The main output circuit has a first state in which the output level of the main output circuit is set to a high level equal to or higher than the forward voltage of the first semiconductor light emitting element and a low level lower than the forward voltage by the switching control signal. It is configured to be switched between two states. The sub-output circuit is inactivated (operation stopped state) when the switching control signal is in the first state, and is activated (operating state) when the switching control signal is in the second state. ).

  In order to enable the main output circuit to be switched between active and inactive, the characteristics of the first semiconductor light emitting element as a load are used. The characteristic is that the semiconductor light emitting device has a forward voltage, and if the applied voltage is at a high level equal to or higher than the forward voltage, a current flows through the semiconductor light emitting device, but the applied voltage is at a low level less than the forward voltage. For example, the current does not flow in the semiconductor light emitting device. If no current flows through the first semiconductor light emitting device, the main output circuit is substantially inactive and is substantially in no load. Therefore, the switching control signal is set to the first state, the applied voltage is set to a high level equal to or higher than the forward voltage, and a current is passed through the first semiconductor light emitting element. The switching control signal is set to the second state, and the applied voltage is set to a low level lower than the forward voltage so that no current flows through the first semiconductor light emitting element.

  According to the present invention, since the switching transformers necessary as the driving source for the main output circuit and the driving source for the sub output circuit are unified, a separate switching transformer is used as the driving source for these two output circuits. Compared to the conventional example of the two-transformer system, the circuit configuration can be simplified and the product cost is expected to be reduced.

Configuration diagram of a power supply device according to an embodiment of the present invention 1 is a configuration diagram of an input line switching circuit in a power supply device according to an embodiment of the present invention. 1 is a configuration diagram of an input line switching circuit in a power supply device according to an embodiment of the present invention. Configuration diagram of a power supply device according to an embodiment of the present invention Configuration diagram of a power supply device according to an embodiment of the present invention The circuit diagram of the power supply device of the Example of this invention The circuit diagram of the power supply device of the Example of this invention Configuration diagram of a conventional power supply device

  Hereinafter, a power supply device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a power supply device according to an embodiment of the present invention. In FIG. 1, 30 is a switching power supply circuit, 40 is a switching transformer, 50 is a main output circuit, 60 is a sub output circuit, 70 is a first semiconductor light emitting element, and 80 is a second semiconductor light emitting element. The output side of the switching power supply circuit 30 is connected to the primary winding N0 of the switching transformer 40. The switching transformer 40 has a first secondary winding N1 and a second secondary winding N2 as its secondary winding, and a main output circuit 50 is connected to the first secondary winding N1, A sub output circuit 60 is connected to the second secondary winding N2. The first semiconductor light emitting element 70 is connected to the output side of the main output circuit 50, and the second semiconductor light emitting element 80 is connected to the output side of the sub output circuit 60. The main output circuit 50 feedback-controls the switching power supply circuit 30 with the output, and stabilizes the output. The sub output circuit 60 internally performs feedback control based on the output, and stabilizes the output.

  The main output circuit 50 for driving the first semiconductor light emitting element 70 and the sub output circuit 60 for driving the second semiconductor light emitting element 80 are in an active state (operating state) and an inactive state. (Operation stop state) is required. Therefore, when the main output circuit 50 is in the active state, the sub output circuit 60 is inactivated. On the other hand, when the sub output circuit 60 is switched to the active state by the switching control signal SS, the main output circuit 50 is switched to the inactive state using the switching control signal SS.

  Here, if the switching transformer 40 is a single transformer common to the main output circuit 50 and the sub output circuit 60, two secondary windings for the main output circuit 50 and the sub output circuit 60 (first output) The power of the primary winding N0 is transmitted to both the secondary winding N1 and the second secondary winding N2). Therefore, when the switching control signal SS is in the first state, the main output circuit 50 is activated and the sub output circuit 60 is deactivated. Conversely, when the switching control signal SS is in the second state, the sub output circuit 60 is activated and the main output circuit 50 is deactivated.

  In order to enable the main output circuit 50 to be switched between active and inactive, the characteristics of the first semiconductor light emitting element 70 as a load are used. The characteristic is that the semiconductor light emitting element has a forward voltage Vf, and if the applied voltage is at a high level equal to or higher than the forward voltage Vf, a current flows through the semiconductor light emitting element. If it is a level, it has the property that no current flows through the semiconductor light emitting device. If no current flows through the semiconductor light emitting device, the main output circuit 50 is substantially deactivated. Therefore, when the switching control signal SS is in the first state, the applied voltage is at a high level equal to or higher than the forward voltage Vf, and a current is passed through the first semiconductor light emitting element 70. When the switching control signal SS is in the second state, the applied voltage is applied. The voltage becomes a low level lower than the forward voltage Vf so that no current flows through the first semiconductor light emitting element 70. When no current flows through the semiconductor light emitting element, the main output circuit 50 is substantially in a no-load state.

  The main output circuit 50 includes a state transition unit 55 whose state can be switched by a switching control signal SS. The state transition unit 55 changes the output level of the main output circuit 50 according to the switching control signal SS to a high level state higher than the forward voltage Vf of the first semiconductor light emitting element 70 and a low level state lower than the forward voltage Vf. It is configured to switch to That is, the state transition unit 55 sets the output level of the main output circuit 50 to a high level equal to or higher than the forward voltage Vf when the switching control signal SS is in the first state, and outputs the main output when the switching control signal SS is in the second state. The output level of the circuit 50 is shifted below the forward voltage Vf. The first semiconductor light emitting device 70 is lit by applying a current when the applied voltage is at a high level equal to or higher than the forward voltage Vf due to the nature of the semiconductor, and the current is supplied when the applied voltage is less than the forward voltage Vf. It is shut off and turned off. At this time, the main output circuit 50 is substantially in a no-load state.

  The sub output circuit 60 is configured such that the open / close unit 65 is inserted into the power supply line, and the open / close unit 65 is controlled to open / close by the switching control signal SS, thereby switching the sub output circuit 60 between the inactive state and the active state. ing. That is, when the switching control signal SS is in the first state, the opening / closing part 65 is opened and the sub output circuit 60 is inactivated. At this time, the second semiconductor light emitting element 80 is turned off because the current is cut off. When the switching control signal SS is in the second state, the opening / closing part 65 is closed to switch the sub output circuit 60 to the active state. As a result, a current flows through the second semiconductor light emitting element 80 and lights up.

  In summary, when the switching control signal SS is in the first state, the main output circuit 50 is in the active state, the sub output circuit 60 is in the inactive state, the first semiconductor light emitting element 70 is lit, and the second semiconductor light emitting element 80 is turned off. The reason why the first semiconductor light emitting element 70 is lit is that the output voltage of the main output circuit 50 is at a high level equal to or higher than the forward voltage Vf of the first semiconductor light emitting element 70. When the switching control signal SS is in the second state, the main output circuit 50 is switched to the inactive state and the sub output circuit 60 is switched to the active state, the first semiconductor light emitting element 70 is turned off, The semiconductor light emitting element 80 is turned on. The reason why the first semiconductor light emitting element 70 is turned off is that the output voltage of the main output circuit 50 is less than the forward voltage Vf of the first semiconductor light emitting element 70. That is, the main output circuit 50 and the sub output circuit 60 are in an active state and an inactive state in contradiction with each other.

  In any state, the switching transformer 40 that receives power from the switching power supply circuit 30 in the primary winding N0 has either the first secondary winding N1 or the second secondary winding N2 on the secondary side. But power is induced. Therefore, although both the main output circuit 50 and the sub output circuit 60 are in the power receiving state, with regard to the current flow, the main output circuit 50 outputs an output current in a certain state (switching control signal SS = first state), The sub output circuit 60 cuts off the output current. In another state (switching control signal SS = second state), the sub output circuit 60 outputs an output current, and the main output circuit 50 cuts off the output current. Although the main output circuit 50 receives power from the switching transformer 40, the load of the main output circuit 50 is substantially in a no-load state.

  By devising as described above, the driving transformer of the main output circuit 50 and the switching transformer 40 as the driving source of the sub output circuit 60 can be unified, and the circuit configuration is significantly larger than that of the conventional example of the two transformer system. Simplification can be realized.

  Below, some preferable aspects are demonstrated about the power supply device of the said structure of this invention.

  There exists a preferable aspect as shown in FIG. 2 about the production | generation means of the said switching control signal SS. It inserts an input line switching circuit 20 into an input line 2 from a single DC or AC power supply 1 to the switching power supply circuit 30 and operates in response to an input from the input line switching circuit 20 to switch the control signal. A switching control circuit 90 for generating SS is provided. With regard to the configuration of the input line switching circuit 20, the normally closed contact nc is connected to the switching power supply circuit 30, and the normally open contact no is connected to the switching control circuit 90. And a normally closed contact nc are provided with a unidirectional element 22 having a forward direction from the normally open contact no to the normally closed contact nc. A preferred example of the unidirectional element 22 is a backflow prevention diode.

  In a state where the changeover switch 21 in the input line changeover circuit 20 is connected to the normally closed contact nc, power is supplied from the single power supply 1 to the switching power supply circuit 30. At this time, since the normally open contact no is open and the unidirectional element 22 is connected in the reverse direction, the switching control circuit 90 is inoperative, and the switching control signal SS is in the first state.

  On the other hand, in a state where the changeover switch 21 is connected to the normally open contact no, power is supplied from the single power source 1 to the changeover control circuit 90, the changeover control circuit 90 operates, and the changeover control signal SS is in the second state. Become. At this time, the unidirectional element 22 is connected in the forward direction, and the power supply to the switching power supply circuit 30 is continued through the unidirectional element 22 from the normally open contact no to the normally closed contact nc.

  If there is no short-circuit line 23 with the unidirectional element 22 that short-circuits the normally-open contact no and the normally-closed contact nc, the switching control circuit 90 is supplied with power to the switching power supply circuit 30. Power supply will be cut off. If the unidirectional element 22 is not provided on the line 23, power is supplied not only to the switching power supply circuit 30 but also to the switching control circuit 90 when the changeover switch 21 is connected to the normally closed contact nc.

  As can be easily understood from the above, according to the configuration of the present embodiment, the main operation mode in which the power of the single power supply 1 is supplied only to the switching power supply circuit 30 and the power of the single power supply 1 are Switching to the sub operation mode supplied to both the switching power supply circuit 30 and the switching control circuit 90 can be easily realized.

  In the case where the power source 1 is AC, when power is supplied from the AC power source 1 to the switching power source circuit 30 via the unidirectional element 22, only positive half-wave power is supplied. Is considered to be no problem for the following reasons. That is, when power is supplied through the unidirectional element 22, the supplied power is switched to low power, so that the voltage drop at the primary electrolytic capacitor provided in the switching power supply circuit 30 becomes gradual. Therefore, the required power can be supplied even if the power supply is only a positive half wave.

  The input line switching circuit 20 is not necessarily limited to the transfer contact type change-over switch 21 with the short-circuit line 23 with the unidirectional element 22 as shown in FIG. FIG. 3 shows an example. The first power source 1a and the second power source 1b can be used as an AC or DC power source. As the first power source 1a, for example, a commercial AC power source is conceivable, and as the second power source 1b, a primary battery, a secondary battery, a storage battery, a super capacitor, and the like are conceivable.

  The input line switching circuit 20 is constituted by a combination of a normally closed single-pole single-throw first switch 24 and a normally-open single-pole single-throw second switch 25. The first switch 24 is always closed in both the main operation mode and the sub operation mode. The second switch 25 is opened in the main operation mode and closed in the sub operation mode. When the second switch 25 is closed, the switching control circuit 90 is activated and the switching control signal SS is output.

  As apparent from the comparison between the configuration of FIG. 2 and the configuration of FIG. 3, the configuration of the input line switching circuit 20 is arbitrary.

  The state transition unit 55 that switches the output level of the main output circuit 50 between a high level state higher than the forward voltage Vf of the first semiconductor light emitting element 70 and a low level state lower than the forward voltage Vf by the switching control signal SS. The following configuration is a preferred embodiment. That is, as shown in FIG. 4, the state transition unit 55 performs the feedback control of the switching power supply circuit 30 with the differential voltage between the output voltage of the main output circuit 50 and the output voltage of the sub output circuit 60, thereby controlling the main output circuit 50. The main output voltage stabilization circuit 100 that stabilizes the output voltage includes a voltage shift circuit 110 that shifts down the difference between the output voltages using a switching control signal SS. This shift down causes the target voltage in the output voltage control in the main output circuit 50 to transition to a low level state less than the forward voltage Vf of the first semiconductor light emitting element 70.

  The main output voltage stabilization circuit 100 stabilizes the output level of the main output circuit 50, and uses a differential voltage between the output voltage of the main output circuit 50 and the output voltage of the sub output circuit 60 as a control factor. Is. This differential voltage is large, and in the main operation mode, the output voltage of the main output circuit 50 is kept at a high level state equal to or higher than the forward voltage Vf of the first semiconductor light emitting element 70. When the operation mode is switched from the main operation mode to the sub operation mode by the switching control signal SS, the voltage shift circuit 110 in the state transition unit 55 operates to shift down the output voltage difference. As a result of this downshift, the output voltage of the main output circuit 50 is switched to a low level state lower than the forward voltage Vf of the first semiconductor light emitting element 70, and the first semiconductor light emitting element 70 is brought into a state where no current flows. Transition.

  As will be described later, because the load is a semiconductor light emitting element, it is preferable that both the feedback control of the output voltage of the main output circuit 50 and the feedback control of the output voltage of the sub output circuit 60 are both controlled by constant current. In that case, current detection is performed as a control factor, and control is performed according to the detected current. Of course, the control is performed by converting the detection current into a voltage, but the control factor is the detection current. On the other hand, it is preferable that the control factor of the shift down of the output voltage difference by the voltage shift circuit 110 is the detection voltage. Therefore, as described above, in the main output voltage stabilization circuit 100 using the differential voltage between the output voltage of the main output circuit 50 and the output voltage of the sub output circuit 60 for stabilizing the output level of the main output circuit 50, The output voltage difference is shifted down. As a result, the circuit configuration can be simplified.

  It is a preferable aspect to add the following configuration to the main output circuit 50. That is, as shown in FIG. 5, a feedback control system that operates with the switching power supply circuit 30 is provided as a feedback control system for stabilizing the output. The feedback control system includes a main-side constant current control circuit 51, compares a voltage corresponding to the detected current of the main output circuit 50 with a reference voltage, and feedback-controls the switching power supply circuit 30 according to the difference change. Since the load is a semiconductor light emitting element, the control mode is preferably constant current control.

  The feedback control means of the main output circuit 50 is preferably configured as follows. That is, a shunt resistor is inserted into the power supply line of the main output circuit 50, and the detected voltage corresponding to the output current detected by the shunt resistor is compared with the reference voltage from the power supply line of the sub output circuit 60 by the comparator. The output of the comparator is fed back to the switching power supply circuit 30 via an insulating signal transmission element such as a photocoupler or an electromagnetic relay.

  The sub-output circuit 60 is preferably configured as follows. Referring to FIG. 5, a feedback control system is provided in the sub output circuit 60 itself. The feedback control system includes a sub-side constant current control circuit 61, and current control elements (transistors, MOS transistors, etc.) inserted in the power supply line depending on whether or not the output voltage of the sub-output circuit 60 exceeds a specified value. To control. In this case, the control mode is preferably constant current control because the load is a semiconductor light emitting element.

  As a means for detecting the output voltage of the sub output circuit 60, a shunt regulator that compares the divided voltage of the output terminal voltage of the sub output circuit 60 with an internal reference voltage is preferable.

  The opening / closing unit 65 that switches the sub output circuit 60 between the inactive state and the active state by the switching control signal SS is preferably configured as follows. That is, an open / close element (IGBT element, MOS transistor, etc.) is inserted into the output line of the sub output circuit 60. When the switching control signal SS is in the first state, the switching element is opened, and when the switching control signal SS is active, the switching element is switched to the closed state.

  Embodiments of a power supply apparatus according to the present invention will be described below in detail with reference to the drawings.

  6 and 7 are circuit diagrams showing the configuration of the power supply apparatus according to the embodiment of the present invention. The circuit of FIG. 6 and the circuit of FIG. 7 are connected by the G1-G2 line at the right end of FIG. 6 and the left end of FIG.

  First, the components are listed. 6 and 7, 10 is an AC power source, 11 is a primary side input stage connector, 12 is a secondary side output stage main side connector, 13 is a secondary side output stage sub-side connector, and 20 is a secondary side output stage connector. An input line switching circuit, 30 is a switching power supply circuit, 40 is a switching transformer, 50 is a main output circuit, 60 is a sub output circuit, 70 is a first LED, 80 is a second LED, and 90 is a switching control circuit. The connector 11 is connected to the AC power supply 10, the first LED 70 is connected to the connector 12, and the second LED 80 is connected to the connector 13.

  The input line switching circuit 20 switches between a state in which the AC power supply 10 is connected only to the switching power supply circuit 30 and a state in which the AC power supply 10 is connected to the switching power supply circuit 30 and the switching control circuit 90, as shown in FIG. As shown, it is composed of a changeover switch 21 and a unidirectional diode 22. The configuration of FIG. 3 may be used.

  The switching power supply circuit 30 is a smoothing capacitor comprising a diode bridge DB for full-wave rectification, a smoothing capacitor C1, a choke coil L1, an N-channel MOS transistor Q1, a power factor correction circuit (PFC control circuit) 33, a diode D2, and an electrolytic capacitor. C2, an N channel type MOS transistor Q2 and a primary side main control circuit (converter circuit) 34 are provided.

  The input side of the diode bridge DB is connected to the output side (first output terminal) of the input line switching circuit 20 and the negative electrode of the connector 11, and the output side is connected to the positive power supply line A1 and the negative power supply line B1. Yes. A smoothing capacitor C1 is connected between the positive power supply line A1 and the negative power supply line B1, and a series circuit of a choke coil L1 and a diode D2 is connected to a connection point between the smoothing capacitor C1 and the positive power supply line A1. The cathode of the diode D2 is connected to the positive electrode of the smoothing capacitor C2 and the primary winding N0 of the switching transformer 40. The drain / source of the NMOS transistor Q1 is connected between the connection point of the choke coil L1 and the anode of the diode D2 and the negative power supply line B1, and the control output terminal of the power factor correction circuit 33 is connected to the gate thereof. The power factor correction circuit 33 controls the switching of the NMOS transistor Q1 so that the current flowing through the AC power supply 10 is sinusoidal.

  A smoothing capacitor C2 made of an electrolytic capacitor is connected between the cathode of the diode D2 and the negative power supply line B1. The primary winding N0 of the switching transformer 40 and the NMOS transistor Q2 are connected between both ends of the smoothing capacitor C2. The control output terminal of the primary main control circuit 34 is connected to the gate of the NMOS transistor Q2. The primary main control circuit 34 is related to feedback control from the secondary side (details will be described later).

  The main output circuit 50 includes a diode D3, a smoothing capacitor C3 made of an electrolytic capacitor, and a shunt resistor R1. The anode of the diode D3 is connected to the positive side of the first secondary winding N1 in the switching transformer 40, and the smoothing capacitor C3 is connected between the cathode and the negative side of the first secondary winding N1. . The positive electrode terminal of the smoothing capacitor C3 is connected to the positive electrode of the connector 12, and the negative electrode of the connector 12 is connected to the negative electrode terminal of the smoothing capacitor C3 via the shunt resistor R1. A first LED 70 is connected to the connector 12. LED (light emitting diode) is an example of a semiconductor light emitting device.

  On the other hand, the sub output circuit 60 includes a diode D4, a smoothing capacitor C4 made of an electrolytic capacitor, a sub-side constant current control circuit 61, a current limiting resistor R11, a pull-up resistor R14, and a smoothing capacitor C5. The sub-side constant current control circuit 61 includes NPN transistors Tr1, Tr2, Tr3, resistors R2, R3, R4, R5, R6, R7, R8, R9, R10 and a shunt regulator SR. In the switching transformer 40, the anode of the diode D4 is connected to the positive side of the second secondary winding N2, and the smoothing capacitor C4 is connected between the cathode and the negative side of the second secondary winding N2. .

  The configuration of the sub-side constant current control circuit 61 is as follows. A series circuit of a resistor R2, a resistor R3, and a transistor Tr1 is connected between both ends of the smoothing capacitor C4. The collector of the transistor Tr2 is connected to the positive terminal of the smoothing capacitor C4, the emitter thereof is connected to the base of the transistor Tr3, and the base of the transistor Tr2 is connected to the connection point of the resistors R2 and R3. The base of the transistor Tr2 is connected to the base of the transistor Tr3 via the resistor R4. The collector of the transistor Tr3 is connected to the positive terminal of the smoothing capacitor C4, and the emitter thereof is connected to the base via the resistor R5. A series circuit of starting resistors R6, R7, and R8 is connected between the collector of the transistor Tr3 and the negative power supply line B3. The base of the transistor Tr1 is connected to the connection point between the resistor R7 and the resistor R8. A cathode of the shunt regulator SR is connected to a connection point between the resistors R6 and R7, and an anode thereof is connected to the negative power supply line B3. A series circuit (resistance dividing circuit) of a resistor R9 and a resistor R10 is connected between the positive power supply line A3 and the negative power supply line B3 in the sub-side constant current control circuit 61, and the shunt regulator SR is connected to the connection point of both the resistors R9 and R10. The reference terminal is connected. A smoothing capacitor C5 is connected between the positive power supply line A3 and the negative power supply line B3 in the sub-side constant current control circuit 61. The positive terminal of the smoothing capacitor C5 is connected to the positive terminal of the connector 13 via the current limiting resistor R11. A second LED 80 is connected to the connector 13. The negative electrode of the connector 13 is connected to the negative power supply line B3 via the N channel type MOS transistor Q3. The NMOS transistor Q3 corresponds to the opening / closing portion 65 and the opening / closing element described above. The drain of the NMOS transistor Q3 is connected to the negative electrode of the connector 13, its source is connected to the negative power supply line B3, and its gate is connected to the output terminal T1 of the switching control circuit 90. The source of the NMOS transistor Q3 is connected to the negative power supply line B3 extending from the second secondary winding N2.

  Next, the main-side constant current control circuit 51 for feedback control between the main output circuit 50 and the switching power supply circuit 30 will be described. The main-side constant current control circuit 51 includes a comparator Cm1 configured by an operational amplifier, a backflow prevention diode D6, a photocoupler PC1, and resistors R12, R13, R14, R15, R16, and R17. The inverting input terminal (−) of the comparator Cm1 is connected to the negative power supply line B2 of the main output circuit 50 through a series circuit of resistors R13 and R12. The connection point is a connection point between the connector 12 and the shunt resistor R1. The non-inverting input terminal (+) of the comparator Cm1 is connected to the connection point between the resistors R15 and R16. The resistor R16 is connected to the negative power supply line B3, and the pull-up resistors R15 and R14 are connected to the positive power supply line A3 of the sub output circuit 60. The output terminal of the comparator Cm1 is connected to the cathode of the backflow prevention diode D6, and its anode is connected to the cathode of the light emitting diode D5 in the photocoupler PC1. The anode of the light emitting diode D5 in the photocoupler PC1 is connected to the positive power supply line A3 via the resistor R17. The collector of the phototransistor P5 in the photocoupler PC1 is connected to the control input terminal of the primary side main control circuit 34, and the emitter thereof is connected to the negative power supply line B1.

  Next, the main output voltage stabilization circuit 100 between the main output circuit 50 and the sub output circuit 60 will be described. The main output voltage stabilizing circuit 100 performs feedback control of the switching power supply circuit 30 based on the difference between the output voltage of the main output circuit 50 and the output voltage of the sub output circuit 60. The main output voltage stabilization circuit 100 includes a comparator Cm2 composed of an operational amplifier, and a backflow prevention. A diode D7, a photocoupler PC1, and resistors R14, R17, R18, R19, R20, R21, and R22 are provided. The main output voltage stabilization circuit 100 constitutes a part of the state transition unit 55 described above.

  The inverting input terminal (−) of the comparator Cm2 is connected to the connection point of the resistors R18 and R19. The other end of the pull-up resistor R18 is connected to the positive power supply line A2 of the main output circuit 50, and the other end of the resistor R19 is connected to the negative power supply line B3 of the sub output circuit 60. The non-inverting input terminal (+) of the comparator Cm2 is connected to the positive power supply line A3 of the sub output circuit 60 via the pull-up resistors R20 and R14. The non-inverting input terminal (+) is connected to the negative power supply line B3 of the sub output circuit 60 through the resistors R21 and R22. The output terminal of the comparator Cm2 is connected to the cathode of the backflow prevention diode D7, and its anode is connected to the cathode of the light emitting diode D5 in the photocoupler PC1.

  The switching control circuit 90 includes a current limiting resistor R23, resistors R24, R25, and R26, a backflow prevention diode D8, a Zener diode (constant voltage diode) ZD, a smoothing capacitor C6 including an electrolytic capacitor, and a photocoupler PC2. One end of the current limiting resistor R23 is connected to the second output terminal of the input line switching circuit 20, and the other end is connected to the anode of the backflow prevention diode D8. The cathode of the backflow prevention diode D8 is connected to the positive electrode of the Zener diode ZD and the positive electrode of the smoothing capacitor C6, and the respective negative electrodes are connected to the negative electrode of the connector 11. The anode of the light emitting diode D9 of the photocoupler PC2 is connected to the positive electrode of the capacitor C6, and the cathode is connected to the negative electrode of the capacitor C6 via the resistor R24. The collector of the phototransistor P9 in the photocoupler PC2 is connected to the positive power supply line A3 in the sub output circuit 60, and the emitter thereof is connected to the negative power supply line B3 of the sub output circuit 60 via the resistors R25 and R26. The connection point between the resistors R25 and R26 is connected to the output terminal T1, and the output terminal T1 is connected to the gate of the NMOS transistor Q3. Further, the connection point between the phototransistor P9 and the resistor R25 is connected to the output terminal T2, the output terminal T2 is connected to the negative power supply line B3 via the resistors R27 and R28, and the connection point between the resistors R27 and R28 is NPN. Is connected to the base of the type transistor Tr4.

  Next, the voltage shift circuit 110 will be described. The voltage shift circuit 110 constitutes a part of the state transition unit 55 described above. That is, the main output voltage stabilization circuit 100 and the voltage shift circuit 110 constitute a state transition unit 55. The voltage shift circuit 110 includes an NPN transistor Tr4 and resistors R21, R22, R27, and R28. The resistors R21 and R22 are also components of the main output voltage stabilization circuit 100. The collector of the transistor Tr4 is connected to the connection point of the resistors R21 and R22, and the emitter is connected to the negative power supply line B3. The base of the transistor Tr4 is connected to the connection point between the resistor R27 and the resistor R28.

  <Description of Operation> Next, the operation will be described.

  The operation mode of the power supply device of the present embodiment includes a main operation mode in which the first LED 70 is lit and a sub operation mode in which the second LED 80 is lit.

(1) Main operation mode First, the main operation mode will be described. In the main operation mode, the input line switching circuit 20 is set to supply power only to the switching power supply circuit 30. Note that, in a sub-operation mode described later, the power is supplied to both the switching power supply circuit 30 and the switching control circuit 90. These two states can be switched asymmetrically. In the main operation mode, power is not supplied from the input line switching circuit 20 to the switching control circuit 90. Accordingly, the switching control signal SS1 from the output terminal T1 of the switching control circuit 90 and the switching control signal SS2 from the output terminal T2 are both at the “L” level, and the NMOS transistor Q3, which is an open / close element in the sub output circuit 60, is in the OFF state. It has become. That is, the second LED 80 is maintained in an extinguished state.

  In the main operation mode, the AC voltage input from the AC power supply 10 via the input line switching circuit 20 is full-wave rectified in the diode bridge DB, and further smoothed by the smoothing capacitor C1 to become a DC voltage. By switching the NMOS transistor Q1 under the control of the power factor correction circuit 33, electromagnetic energy is accumulated in the choke coil L1 and the operation of releasing the energy is repeated to improve the power factor. Further, the current is rectified by the diode D2 and smoothed by the smoothing capacitor C2.

  Further, when the NMOS transistor Q2 is turned on / off under the control of the primary side main control circuit 34, an AC voltage is induced from the primary winding N0 of the switching transformer 40 to the first and second secondary windings N1, N2. Is done. In the main output circuit 50, the rectifier diode D3 and the smoothing capacitor C3 generate a secondary side DC voltage, and a direct current is supplied to the first LED 70 via the connector 12 to light the first LED 70.

  Feedback control from the main output circuit 50 to the switching power supply circuit 30 in the main operation mode is performed by constant current control. The current flowing through the main output circuit 50 is detected in the form of voltage by the shunt resistor R1 in the main output circuit 50. The detection voltage (detection current) is applied to the inverting input terminal (−) of the comparator Cm1 via the resistors R12 and R13. The reference voltage divided by the series pull-up resistors R14 and R15 and the resistor R16 is applied to the non-inverting input terminal (+) of the comparator Cm1. When the output current of the main output circuit 50 increases and the detection voltage at the shunt resistor R1 exceeds the reference voltage of the comparator Cm1, the output terminal of the comparator Cm1 is inverted from the “H” level to the “L” level. As a result, the diode D6 becomes conductive, and a current flows through the light emitting diode D5 of the photocoupler PC1. Light from the light emitting diode D5 enters the phototransistor P5, and the phototransistor P5 is turned on. As a result, the feedback control signal FC is given to the primary main control circuit 34, and the primary main control circuit 34 inverts and controls the NMOS transistor Q2. As a result, the current flowing through the main output circuit 50 is reduced.

  On the other hand, when the output current of the main output circuit 50 decreases and the detection voltage at the shunt resistor R1 falls below the reference voltage of the comparator Cm1, the output terminal of the comparator Cm1 is inverted from the “L” level to the “H” level. As a result, the diode D6 is switched to the non-conductive state, and the current of the light emitting diode D5 of the photocoupler PC1 is cut off. As a result, the feedback control signal FC becomes invalid, and the NMOS transistor Q2 is inverted and controlled to be on. As a result, the current flowing through the main output circuit 50 increases.

  By repeating the above control operation, the current flowing through the main output circuit 50 is stabilized at a specified value.

  In the main operation mode, as described above, the switching control signal SS2 from the output terminal T2 of the switching control circuit 90 is at the “L” level, and the transistor Tr4 of the voltage shift circuit 110 is off. At this time, a voltage drop across the series resistors R21 and R22 is applied to the non-inverting input terminal (+) of the comparator Cm2 in the main output voltage stabilization circuit 100. As a result, the output of the comparator Cm2 is “H” level, the backflow prevention diode D7 is non-conductive, the photocoupler PC1 is off, and the NMOS transistor Q2 of the switching power supply circuit 30 is on. At this time, the level of the stable output voltage of the main output circuit 50 is stabilized at a constant level sufficiently higher than the forward voltage Vf of the first LED 70. The forward voltage Vf of the first LED 70 is approximately 60 to 80 [V]. Here, when the forward voltage Vf is set to 70 [V], for example, the level of the stable output voltage of the main output circuit 50 is set. For example, the resistance values of the resistors R18, R19, R20, R21, and R22 may be set to 80 [V]. With this setting, since the stable output voltage level 80 [V] of the main output circuit 50 exceeds the forward voltage Vf (= 70 [V]) of the first LED 70, the first output voltage level 80 [V] A current flows through the LED 70, and the first LED 70 is lit as expected.

  Since the NMOS transistor Q3 is off as described above, the sub output circuit 60 is in an inactive state, and the second LED 80 is turned off.

(2) Sub operation mode Next, the sub operation mode will be described. When line switching is performed in the input line switching circuit 20, switching from the power supply state only to the switching power supply circuit 30 until then to the power supply state to both the switching power supply circuit 30 and the switching control circuit 90 is performed. Is called. In the switching control circuit 90, the current is limited by the current limiting resistor R23, and the smoothing capacitor C6 is charged via the backflow prevention diode D8. The charging voltage to the smoothing capacitor C6 is determined by the breakdown voltage of the Zener diode ZD. When a current flows through the light emitting diode D9 of the photocoupler PC2 and the phototransistor P9 is turned on, a predetermined voltage is applied to the connection point of the division resistors R25 and R26 and the connection point of the division resistors R27 and R28. As a result, the switching control signal SS1 for the NMOS transistor Q3 of the sub output circuit 60 and the switching control signal SS2 for the transistor Tr4 of the voltage shift circuit 110 are both activated and become effective.

  When the switching control signal SS1 is inverted from the “L” level to the “H” level, the NMOS transistor Q3 that has been in the off state so far is inverted and switched to the on state, and a current flows through the sub output circuit 60. As a result, the alternating current induced from the primary winding N0 of the switching transformer 40 to the second secondary winding N2 generates a secondary side DC voltage by the rectifier diode D4 and the smoothing capacitor C4, and the sub-side constant current control is performed. A direct current is supplied from the transistor Tr3 and the current limiting resistor R11 in the circuit 61 to the second LED 80 via the connector 13 to light the second LED 80.

  The operation of the sub-side constant current control circuit 61 at this time is performed as follows. The current from the positive terminal of the smoothing capacitor C4 flows into the negative power supply line B3 through the starting resistors R6, R7, R8. The transistor Tr1 is turned on by the voltage across the starting resistor R8, and the transistors Tr2 and Tr3 are also turned on in conjunction. The smoothing capacitor C5 is charged through the transistor Tr3 in which the current from the smoothing capacitor C4 is turned on, and the voltage level of the positive power supply line A3 increases.

  The charging current for the smoothing capacitor C5 is monitored by dividing resistors R9 and R10. The voltage drop across the voltage dividing resistor R10 is applied to the reference terminal of the shunt regulator SR. When the voltage drop across the voltage dividing resistor R10 exceeds the reference voltage of the shunt regulator SR due to an increase in charging current, the shunt regulator SR is turned on. Since the series resistors R7 and R8 are short-circuited, the collector current of the transistor Tr1 is reduced. In conjunction with this, the collector current of the transistor Tr3 is also reduced, and the charging current for the smoothing capacitor C5 is suppressed. On the other hand, when the voltage drop across the voltage dividing resistor R10 falls below the reference voltage of the shunt regulator SR due to the decrease in the charging current, the shunt regulator SR is turned off and the series resistors R7 and R8 are connected, so that the collector of the transistor Tr1 The current increases. In conjunction with this, the collector current of the transistor Tr3 also increases, and the charging current for the smoothing capacitor C5 increases. By repeating the operation of the sub-side constant current control circuit 61, the current flowing through the positive power supply line A3 of the sub output circuit 60 is stabilized. This current is limited by the current limiting resistor R11, supplied to the second LED 80, and the second LED 80 is turned on. The rated voltage of the second LED 80 is 4 to 12 [V], which is considerably lower than the rated voltage of 60 to 80 [V] of the first LED 70. Therefore, the current supplied to the second LED 80 is limited by the current limiting resistor R11.

  On the other hand, when the switching control signal SS2 of the output terminal T2 in the switching control circuit 90 is activated and becomes effective, the transistor Tr4 in the voltage shift circuit 110 becomes conductive, and the resistor R22 in the main output voltage stabilization circuit 100 is short-circuited. As a result, the voltage applied to the non-inverting input terminal (+) of the comparator Cm2 in the main output voltage stabilization circuit 100 is lowered, and the output terminal of the comparator Cm2 is inverted from the previous “H” level to the “L” level. . As a result, the backflow prevention diode D7 becomes conductive, the photocoupler PC1 functions in the same manner as described above, the NMOS transistor Q2 is turned off via the primary side main control circuit 34 of the switching power supply circuit 30, and the positive power supply of the main output circuit 50 The voltage on line A2 decreases. The voltage applied to the non-inverting input terminal (+) of the comparator Cm2 when the positive power supply line A2 is inverted and rises next is greatly different between before and after the transistor Tr4 is turned on. This corresponds to the voltage of the positive power supply line A2 falling below the forward voltage Vf of the first LED 70.

  The forward voltage Vf of the first LED 70 is 60 to 80 [V], and the forward voltage Vf of the second LED 80 is 4 to 12 [V]. Now, assuming that the forward voltage Vf of the first LED 70 is 70 [V], the stable voltage of the positive power supply line A2 before the transistor Tr4 is turned on is, for example, 80 [V], and the positive power supply after the transistor Tr4 is turned off. The stable voltage of the line A2 is set to 50 [V]. The resistance values of the resistors R18, R19, R20, R21, R22, and R23 of the main output voltage stabilization circuit 100 are set so as to be so.

  In the sub operation mode, the transistor Tr4 of the voltage shift circuit 110 is turned on as described above, and the stable voltage of the positive power supply line A2 of the main output circuit 50 becomes the forward voltage Vf (= 70 [V] ( As a result of the lower voltage (50 [V] (example)) than the example)), no current flows through the first LED 70 which is a semiconductor light emitting element, and the first LED 70 is switched from the lit state to the unlit state. Become.

  In summary, in the main operation mode, the NMOS transistor Q3 in the sub output circuit 60 is turned off, and in the sub operation mode, the output voltage of the main output circuit 50 is set to the forward voltage Vf of the first LED 70. The current is prevented from flowing through the first LED 70 as a voltage lower than. Therefore, the second secondary winding N2 at the input end of the sub output circuit 60 may be kept active in the main operation mode, or the first secondary at the input end of the main output circuit 50 in the sub operation mode. This means that the winding N1 may be kept in an active state. That is, only one switching transformer 40 may be used as the switching transformer to be used even though the output circuit on the secondary side has two output circuits of the main output circuit 50 and the sub output circuit 60. It is.

  Here, the power source of the switching control circuit 90 is considered. The power source is the same AC power supply 10 as the power source of the switching power supply circuit 30. By switching the path in the input line switching circuit 20 while using the common AC power supply 10 as a power source, the power supply state only to the switching power supply circuit 30 and the power to both the switching power supply circuit 30 and the switching control circuit 90 The supply state must be switched.

  As a device for that, it is configured as shown in FIG. The change-over switch 21 has a transfer contact configuration, its common terminal is connected to the positive electrode of the connector 11, its normally closed contact nc is connected to the input side of the diode bridge DB in the switching power supply circuit 30, and its normally open contact no is The switching control circuit 90 is connected to a current limiting resistor R23. Furthermore, the unidirectional element 22 is connected between the normally open contact no and the normally closed contact nc. The anode of the unidirectional element 22 is connected to the normally open contact no, and its cathode is connected to the normally closed contact nc.

  Since the input line switching circuit 20 is configured with such a changeover switch 21 with the unidirectional element 22, power is supplied only to the switching power supply circuit 30 while the power source is the common single AC power supply 10. The state and the power supply state to both the switching power supply circuit 30 and the switching control circuit 90 can be switched.

  However, if a separate DC power source such as a dry cell or a supercapacitor can be used in addition to the AC power source 10, the input line switching circuit 20 is not necessarily required. It is only necessary to interpose a switch means between the DC power supply and the switching control circuit 90. In that case, it is only necessary to provide single-pole single-throw switch means on the input line.

  The present invention is a power supply device for driving the first and second semiconductor light emitting elements in a contradictory manner, such as an LED illumination power supply device with a safety light, and the circuit configuration is simplified as compared with the conventional two transformer system. It is useful as a technology to realize.

20 Input line switching circuit 21 Changeover switch 22 Unidirectional element (diode)
DESCRIPTION OF SYMBOLS 30 Switching power supply circuit 40 Switching transformer 50 Main output circuit 51 Main side constant current control circuit 55 State transition part 60 Sub output circuit 61 Sub side constant current control circuit 70 1st semiconductor light-emitting device (LED)
80 Second semiconductor light emitting device (LED)
90 switching control circuit 100 main output voltage stabilization circuit (state transition unit)
110 Voltage shift circuit (state transition unit)
Cm1, Cm2 Comparator N0 Primary winding N1 First secondary winding N2 Second secondary winding PC1, PC2 Photocoupler (insulated signal transmission element)
Q2 NMOS transistor (switching element)
Q3 NMOS transistor (switching element)
R1 shunt resistor SS1, SS2 switching control signal SR shunt regulator Tr3 NPN transistor (current control element)
Tr4 NPN transistor (voltage shift circuit drive element)

Claims (8)

A switching power supply circuit;
A switching transformer having a primary winding connected to the output side of the switching power supply circuit;
A main output circuit connected to the first secondary winding of the switching transformer and outputting to the first semiconductor light emitting element;
A sub-output circuit connected to the second secondary winding of the switching transformer and outputting to the second semiconductor light emitting element,
The main output circuit has a first state in which the output level of the main output circuit is set to a high level equal to or higher than the forward voltage of the first semiconductor light emitting element and a low level lower than the forward voltage by the switching control signal. Configured to be switched between two states,
The sub output circuit is configured to be inactivated when the switching control signal is in the first state, and to be activated when the switching control signal is in the second state. . The switching control signal generating means includes an input line switching circuit inserted in an input line of the switching power supply circuit,
A switching control circuit that operates in response to an input from the input line switching circuit and generates the switching control signal;
The input line switching circuit includes a transfer contact type changeover switch in which a normally closed contact is connected to the switching power supply circuit and a normally open contact is connected to the switching control circuit, and the normally open contact and the normally closed contact. The power supply device according to claim 1, further comprising a unidirectional element having a forward direction from the normally open contact to the normally closed contact. 3. The output voltage of the main output circuit is stabilized through feedback control of the switching power supply circuit with a differential voltage between the output voltage of the main output circuit and the output voltage of the sub output circuit. In the power supply of
A power supply apparatus comprising a voltage shift circuit that shifts down the difference between the output voltages in accordance with the switching control signal.   The main output circuit has a feedback control system with the switching power supply circuit, and the feedback control system compares a voltage corresponding to the detected current of the main output circuit with a reference voltage, and changes the difference according to the difference change. The power supply apparatus according to claim 1, further comprising a main-side constant current control circuit that performs feedback control of the switching power supply circuit.   The feedback control means of the main output circuit is a comparator that compares a detected voltage corresponding to an output current detected by a shunt resistor inserted in a power supply line of the main output circuit with a reference voltage from the power supply line of the sub output circuit. 5. The power supply apparatus according to claim 4, wherein the power supply apparatus is configured to feed back to the switching power supply circuit via an insulated signal transmission element.   The sub output circuit has a feedback control system therein, and the feedback control system controls a current control element inserted in the feeder line according to whether or not the output voltage of the sub output circuit exceeds a specified value. The power supply device according to any one of claims 1 to 5, further comprising a side constant current control circuit.   7. The power supply apparatus according to claim 6, wherein the output voltage detection means of the sub output circuit is a shunt regulator that compares the resistance-divided voltage of the output terminal voltage of the sub output circuit with an internal reference voltage.   The means for switching the sub output circuit between an inactive state and an active state by the switching control signal inserts an opening / closing element into an output line of the sub output circuit, and the opening / closing element is turned on when the switching control signal is in the first state. The power supply device according to any one of claims 1 to 7, wherein an element is in an open state, and the switching element is switched to a closed state when the switching control signal is in the second state.

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