JP6336349B2 - Power supply - Google Patents

Description

  The present invention relates to a power supply device including an auxiliary power supply circuit for a control circuit. For example, it is suitable for an illumination power source used for lighting an illumination LED.

  In recent years, the performance of light emitting diodes has increased, and the life of lighting fixtures using light emitting diodes has also increased. For this reason, replacement of conventional light sources with light-emitting diode lighting fixtures is in progress. In the future, if the performance of the light-emitting diode is further improved, it is considered that the light-emitting diode lighting fixture will be adopted also in the field of general-purpose lighting fixtures. Hereinafter, the light emitting diode is referred to as an LED (Light Emitting Diode).

  In a lighting fixture using a large number of LED elements, there is no restriction on the structure due to the shape of the lamp as compared with a lighting fixture using a conventional HID lamp, and a lighting fixture having a free shape is realized. Moreover, although the light output per LED element is small, the light output in the whole LED element is ensured by combining many these in series and parallel. Recently, conventional HID lamps are also being replaced with LED lighting fixtures.

JP 2001-103743 A (FIG. 1)

  The LED lighting apparatus includes a light emitter configured by serially paralleling a large number of LED elements. However, the configuration of the LED lighting apparatus is various because it is based on a unique design of many business operators. The voltage and current to be applied to the light emitting device in which a plurality of LED elements are combined also vary. This is in contrast to HID lamps, which have been established as a global standard. In a power supply device for LED lighting, a general-purpose product cannot be used for a choke coil of a built-in power factor correction circuit or a flyback transformer, and it is necessary to redesign.

  Such a situation greatly affects the design of the auxiliary power supply circuit for the control circuit of the power supply apparatus. This is because, conventionally, with regard to auxiliary power, there has been a general method of extracting auxiliary power from a choke coil of a power factor correction circuit or an auxiliary winding added to a flyback transformer or the like due to the restriction of minimizing the number of parts. (See Patent Document 1). In the power supply device for LED lighting, it is necessary to newly design the auxiliary winding added to the choke coil and the flyback transformer each time the choke coil and flyback transformer are designed.

  Thus, when adopting LED lighting fixtures, it is necessary to newly develop a power supply device including an auxiliary power supply circuit in accordance with the individual configuration of the LED lighting fixtures, and there is a problem in terms of delivery time. . The present invention has been made in view of the above-described problems, and provides a power supply device including a new auxiliary power supply circuit for a control circuit without using a conventional method of taking out auxiliary power by adding an auxiliary winding. For the purpose.

  The power supply device according to the present invention is a so-called switching power supply circuit, and has a circuit configuration such as a step-down method, a step-up method, a step-up / step-down method, or a flyback method. Common circuit elements include an inductance element, a switching element, and a capacitor for DC power supply. These connection methods differ depending on the switching method, but are common in that an input voltage such as a rectified voltage is supplied to an inductance element such as a choke coil or a flyback transformer. Further, it is common that the switching element switches the voltage between the terminals of the inductance element and that the DC power supply capacitor is charged with the operation of storing and releasing the energy of the magnetic field of the inductance element. . It is common to provide a control circuit for driving the switching element and an auxiliary power circuit for the control circuit. The output voltage is supplied to various external loads by the electric charge accumulated in the DC power supply capacitor.

  The inventor completed the present invention by paying attention to a method of extracting auxiliary power from a rectangular wave voltage generated between the terminals of the switching element as the switching power supply circuit is driven on and off.

  That is, a characteristic of the power supply device according to the present invention is that, based on the switching power supply circuit, the auxiliary power supply circuit further includes an auxiliary power supply capacitor, and a positive terminal of the auxiliary power supply capacitor is connected to the switching power supply circuit. Among the two terminals of the element, it is connected to the terminal on the side where the potential fluctuates between the high level and the low level as it is driven. The auxiliary power supply capacitor is charged by applying a high-level potential and supplies the accumulated positive charge to the control circuit.

  Here, by the basic operation of the switching power supply circuit, magnetic field energy is accumulated in the inductance element in the switching on state, and magnetic field energy is released from the inductance element in the off state. Note that, depending on the connection position of the switching element in the switching power supply circuit, the voltage between the terminals of the switching element is high level in the off state (low level in the on state), and conversely the high level in the on state. (Low level in the off state).

  According to the configuration of the present invention, the positive electrode terminal of the capacitor for the auxiliary power supply is connected to the terminal of the switching element (referred to as the potential fluctuation side terminal) whose potential changes alternately between the high level and the low level. When the terminal on the potential fluctuation side of the switching element is at high level, the potential difference between the high level voltage and the ground line is applied to the auxiliary power supply capacitor and charged. When the terminal on the potential fluctuation side of the switching element is at a low level, a sufficient potential difference is not applied to the auxiliary power supply capacitor, so that charging is not performed.

  In any case, when the terminal on the potential fluctuation side of the switching element is at a high level, the auxiliary power supply capacitor is charged. Accordingly, since the charging is repeatedly performed by driving the switching element, the charging state of the auxiliary power supply capacitor is maintained, and the supply of auxiliary power to the control circuit is stabilized.

  Here, the auxiliary power supply circuit has a voltage dividing circuit connecting the potential variation side terminal of the switching element and a ground line, and the auxiliary power supply capacitor has a potential after voltage division by the voltage dividing circuit. Preferably a level is applied. According to this configuration, the voltage on the high level side of the rectangular wave voltage generated between the terminals of the switching element can be easily lowered to a level suitable for the auxiliary power source for the control circuit.

  The voltage dividing circuit is preferably a series connection circuit of a plurality of voltage dividing capacitors. Although a voltage dividing circuit using a series connection circuit of resistance elements may be used, the series connection circuit of capacitors is better because the resistance elements generate heat. In the case of a series connection circuit of capacitors, a voltage peak (noise) may occur when switching is turned off. Therefore, it is better to insert an inductance element for noise prevention at the connection between the switching element and the capacitor.

  In addition, the auxiliary power supply circuit includes a discharge limiting rectifying element that connects a potential level after voltage division by the series connection circuit and a positive electrode terminal of the auxiliary power supply capacitor, and the discharge limiting rectifying element. Are preferably connected in a direction that limits the discharge of the positive charge accumulated in the auxiliary power supply capacitor. According to this configuration, even if the terminal on the potential fluctuation side of the switching element is at a low level, the discharge limiting rectifier surely prevents the backflow of the positive charge from the auxiliary power supply capacitor.

  Further, the auxiliary power supply circuit includes a rectifier for replenishing positive charges connecting the potential level after voltage division by the series connection circuit and the ground line. It is preferable that the potential level point after the voltage division of the voltage dividing circuit is connected from the ground line so as to replenish positive charges.

  When a series connection circuit of voltage dividing capacitors is used, when the potential fluctuation side terminal of the switching element switches to a low level, the positive charge charged in the voltage dividing capacitor connected to the potential fluctuation side terminal moves (discharges). Therefore, negative charges are accumulated in the series connection circuit of the voltage dividing capacitors, and a negative potential is easily generated. The inside of the series connection circuit refers to a connection portion between capacitors, that is, a portion where a divided potential is obtained. However, in the present invention, since the rectifying element for replenishing the positive charge is provided, it is possible to prevent the positive charge from moving from the ground line to the inside of the series connection circuit of the voltage dividing capacitor to become a negative potential. Therefore, regardless of the driving of the switching element, the potential state of the voltage dividing capacitor can be stabilized, and the auxiliary power supply capacitor can be reliably charged.

  According to the configuration of the present invention, it is not necessary to use a custom-made part such as a choke coil or a flyback transformer including an additional auxiliary winding for the auxiliary power circuit for the control circuit, and a general-purpose inductance element can be used. Therefore, there are effects such as shortening of delivery time and cost reduction. Further, since the auxiliary power supply capacitor or the voltage dividing capacitor is connected to the switching portion of the switching element, there is a significant reduction effect of noise generation.

1 is an overall configuration diagram of a step-down LED power supply according to a first embodiment of the present invention. It is a whole block diagram of the high side switching step-down LED power supply according to the second embodiment of the present invention. It is a whole block diagram of the pressure | voltage rise type LED power supply which concerns on 3rd Embodiment of this invention. It is a whole block diagram of the step-up / step-down LED power supply according to the fourth embodiment of the present invention. It is a whole block diagram of the buck-boost type LED power supply which concerns on 5th Embodiment of this invention. The whole block diagram of the flyback type LED power supply concerning a 6th embodiment of the present invention. The figure for demonstrating the voltage waveform of the P point of FIG. 1 and FIGS. The figure for demonstrating the voltage waveform of the P point of FIG.

First Embodiment FIG. 1 shows a circuit configuration of a step-down LED power supply for illumination according to a first embodiment of the present invention. In FIG. 1, 1 is an AC power source, 2 is a full-wave rectifier, 3 is an LED light emitter (or LED lighting fixture), 4 is a control circuit, 5 is an auxiliary power circuit, and 6 is a switching circuit. The LED power source includes a full-wave rectifier 2 that rectifies an input voltage from the AC power source 1, a switching circuit 6 that steps down the voltage after rectification and outputs the voltage to the LED light emitter 3, and a control that controls driving of the switching circuit 6. A circuit 4 and an auxiliary power circuit 5 for operating the control circuit 4 are provided.

  The full wave rectifier 2 includes a diode bridge DB and a capacitor C1. A power supply device that does not include a full-wave rectifier may be used. For example, a DC voltage from the outside may be input to the switching circuit 6.

  The switching circuit 6 steps down the voltage after rectification to a predetermined level and outputs it, and is also called a step-down circuit or the like. As shown in FIG. 1, it includes a choke coil L1 as an inductance element of the present invention, an electrolytic capacitor C2 as a DC power supply capacitor, a switching element S1, and a diode D1 as a rectifier for regenerative current. Specific connection states of these circuit elements will be described. First, a series circuit of a choke coil L1, an electrolytic capacitor C2, and a switching element S1 is connected between the terminals of the full-wave rectifier 2. A diode D1 is connected between the terminals of the series circuit of the choke coil L1 and the electrolytic capacitor C2. The unidirectional direction of the diode D1 is set so that the regenerative current from the inductance element L1 flows to the positive electrode side of the electrolytic capacitor C2 during the OFF period of the switching element S1, and returns to the inductance element L1 through the diode D1. Has been.

  The control circuit 4 drives the switching element S1 of the switching circuit. It is preferable to have a function of dimming the LED light emitter 3 by changing the on-duty as well as a function of dropping the input voltage to a predetermined output voltage.

  From here, the structure of the auxiliary power supply circuit 5 characteristic of the present invention will be described.

  The auxiliary power supply circuit 5 is connected to the switching element S1 so that the voltage across the terminals of the switching element S1 in the off state is applied. Further, an auxiliary power supply loop is formed so that positive charges stored in the auxiliary power circuit 5 can be supplied to the control circuit 4 as auxiliary power. The main configuration includes a series connection circuit of voltage dividing capacitors C4 and C5, an electrolytic capacitor C3 for auxiliary power supply, and two diodes D2 and D3.

  The series connection circuit of the voltage dividing capacitors C4 and C5 connects between the terminal (P point) on the potential fluctuation side of the switching element S1 and the ground line connected to the negative terminal of the full-wave rectifier 2, and The voltage on the high level side of the generated rectangular wave voltage is divided to a level suitable for the auxiliary power for the control circuit. When an input AC voltage of 200 V (selected from the range of 50 to 300 V) is supplied to this LED power supply, the high level voltage at point P is also approximately 200 V. On the other hand, since the control voltage is normally 15 V or less (set within a range of 5 to 20 V), the capacitance of the two capacitors constituting the voltage dividing circuit is much larger in C5 than in C4.

  The positive terminal of the electrolytic capacitor C3 is connected to the connection portion between the capacitors C4 and C5. The negative terminal of the electrolytic capacitor C3 is connected to the ground line. In other words, it can be said that the positive terminal of the electrolytic capacitor C3 for auxiliary power is connected to the point P through the voltage dividing circuit of the capacitors C4 and C5. As described above, the point P is a potential fluctuation side terminal on the side where the potential fluctuates between the high level (off state) and the low level (on state) of both terminals of the switching element S1. In this way, the potential level after voltage division is applied to the auxiliary power supply capacitor C3, and charging is performed. A diode D2 is provided on the lead wire from the connecting portion of the voltage dividing capacitors C4 and C5 to the auxiliary power supply capacitor C3. The direction of the diode D2 is such that the positive charge accumulated in the auxiliary power supply capacitor C3 is divided. It is set so that it does not flow backward to the pressure capacitor. That is, it functions as a discharge limiting rectifying element.

  Since the voltage dividing capacitors C4 and C5 and the auxiliary power supply capacitor C3 are connected to the switching portion of the switching element S1 in the auxiliary power supply circuit 5 of the present embodiment, the effect of significantly reducing the generation of noise due to switching. There is. In the case of the series connection of the voltage dividing capacitors C4 and C5, a higher divided voltage is applied to the smaller electrostatic capacity. In this embodiment, since the capacitor C4 has a smaller capacitance than the capacitor C5, a higher voltage is applied. Therefore, the effect of suppressing noise by the capacitor C4 is greater than that of the capacitor C5. If, for example, the capacitance of the capacitor C4 is increased 10 times so that the voltage dividing ratio (capacitance ratio) of the two capacitors C4 and C5 is equal, the noise suppression effect is further improved, but the circuit loss is reduced. It increases significantly and is not practical. The capacity of the capacitor C4 is preferably 5 times or more, more preferably 10 times or more than the capacity of the capacitor C5.

  A diode D3 is connected between the connection portion of the voltage dividing capacitors C4 and C5 and the ground line. The diode D3 corresponds to a rectifying element for replenishing positive charges according to the present invention, and is provided in a direction for replenishing positive charges from the ground line to the connection portion of the voltage dividing capacitors C4 and C5.

  How the auxiliary power supply circuit 5 having such a configuration extracts auxiliary power will be described in detail with reference to FIG. 1 together with the description of the switching operation.

  When the switching element S1 is turned on, a conduction loop is formed from the positive side of the full-wave rectifier 2 to the choke coil L1, the electrolytic capacitor C2, the switching element S1, and the negative side of the full-wave rectifier 2. A rectified DC voltage is applied to the series connection circuit of the choke coil L1 and the electrolytic capacitor C2. For this reason, the rectified input current flows from the high side of the capacitor C1 of the full-wave rectifier 2 through this conduction loop to the low side of the capacitor C1. During this time, the energy of the magnetic field is gradually stored in the choke coil L1, and the electrolytic capacitor C2 is charged.

  When the switching element S1 is turned off, the above-described conduction loop is interrupted and the current is interrupted, so that the accumulation of magnetic field energy in the choke coil L1 stops, and the stored magnetic field energy is gradually released. For this reason, since the regenerative current flows from the choke coil L1 to the electrolytic capacitor C2 and the diode D1 in this order and returns to the choke coil L1, the regenerative current charges the electrolytic capacitor C2.

  When the rectified voltage is applied to the switching circuit 6 in this way, the choke coil L1 and the diode D1 are interlocked by the switching operation, and charge the electrolytic capacitor C2. Due to the accumulated positive charge, an output voltage is applied to the LED light emitter 3 connected between the terminals of the electrolytic capacitor C2, a current flows through the LED light emitter 3, and the LED is lit.

  The point P of the switching element S1 in FIG. 1 is electrically connected to the ground line when turned on, and thus has a low level potential of approximately 0V. When off, the ground line is disconnected and a regenerative current flows due to the release of magnetic field energy from the choke coil L1, so that the point P becomes a high level voltage, which is substantially equal to the rectified voltage. As shown in FIG. 7, the time change of the voltage at point P becomes a high-level (voltage A) voltage waveform in the off state and a low level (voltage B) waveform in the on-state.

  When the voltage at point P of the switching element S1 is at the high level (voltage A) in FIG. 7, the potential A is divided by a series connection circuit of voltage dividing capacitors C4 and C5. Assuming that the capacitors C4 and C5 have no charge in the initial state, application of the potential A charges a positive charge equal to the capacitors C4 and C5. When the potential at the connection portion between the capacitors C4 and C5 rises and the diode D2 is turned on, the positive charge charged in the capacitor C5 moves to the electrolytic capacitor C3 through the diode D2 and charges it. In this way, the potential at the connection portion between the capacitors C4 and C5 rises to the divided voltage value, a predetermined auxiliary voltage is supplied to the electrolytic capacitor C3 and the control circuit 4, and the positive charge stored in the electrolytic capacitor C3 is appropriately changed to the control circuit 4 To flow.

  Next, when the voltage at the point P is the low level (voltage B) in FIG. 7, that is, when the point P becomes the ground level due to switching on, the voltage applied to the series connection circuit of the voltage dividing capacitors C4 and C5. Becomes almost zero. In this case, the positive charge charged in the capacitor C4 moves (releases) to the ground line through the switching element S1. Further, the positive charge from the ground line flows through the diode D3 to the connection portion of the capacitors C4 and C5, and cancels out with the negative charge charged in the negative electrode of the capacitor C4. That is, the discharge of the capacitor C4 is completed. Thus, the potential at the connection portion between the capacitors C4 and C5 becomes the ground level by the diode D3.

  In the auxiliary power supply circuit 5, the above cycle is repeated in response to the voltage at the point P alternately repeating a high level and a low level. Since the electrolytic capacitor C3 is charged when the point P is at a high level, the positive charge is stably charged in the electrolytic capacitor C3, and the control circuit 4 can use the positive charge as auxiliary power for operation. .

  According to the configuration of the present embodiment, the rectangular wave voltage at both ends of the switching element S1 is divided by two capacitors, the divided voltage is rectified and applied to the electrolytic capacitor C3, and this is charged to charge for the control circuit. Can be an auxiliary power source. Conventionally, it is no longer necessary to use a custom-made part such as a choke coil or a flyback transformer including an additional auxiliary winding, and a general-purpose coil or transformer can be used. As a result, effects such as shortened delivery time and cost reduction can be obtained.

  When the point P of the switching element S1 is switched to the low level, the positive charge charged in the voltage dividing capacitor C4 is released, so that a negative charge accumulates at the connecting portion of the voltage dividing capacitors C4 and C5, and the negative charge is accumulated. Potential is generated. In the present embodiment, since the positive load replenishing diode D3 is provided, it is possible to prevent the positive charge from moving from the ground line to the connection portion of the voltage dividing capacitors C4 and C5 to become a negative potential. Therefore, regardless of the driving of the switching element S1, the potential state of the connection portion of the voltage dividing capacitors C4 and C5 can be stabilized, and the electrolytic capacitor C3 can be charged reliably.

  According to the configuration of the present embodiment, the voltage of the electrolytic capacitor C3 is substantially proportional to the high / low repetition frequency (switching frequency) of the P point and the voltage value at the high level of the P point, and the high level of the P point. It is not proportional to the time width, i.e., on-duty. Therefore, even if the LED light emitter 3 is dimmed by changing the time width of the high level at point P, the voltage of the electrolytic capacitor C3 does not fluctuate. For this reason, it can be said that the auxiliary power supply circuit 5 of this embodiment is very easy to handle as compared with the auxiliary power supply circuit using the auxiliary winding of the conventional flyback transformer.

  In the present embodiment, a series connection circuit of two resistors may be employed as the voltage dividing circuit of the auxiliary power supply circuit 5. In this case, since the resistance heat is generated during the off period, the above-described series connection circuit of the capacitors C4 and C5 is preferable. In the case of the capacitors C4 and C5, a voltage peak (noise) may occur when switching is turned off. Therefore, it is better to insert a noise prevention coil between the point P and the capacitor C4 in FIG.

(Application of the present invention to other power supply devices)
The power supply device according to the present invention is not limited to the step-down LED power supply shown in FIG. 1, but includes an LED power supply using various switching circuits shown in FIGS. 2 is a step-down LED power supply of high-side switching type, FIG. 3 is a step-up type LED power supply, FIG. 4 is a step-up / step-down type LED power supply, and FIG. FIG. 6 shows a flyback-type LED power supply. Although not shown, the present invention can also be applied to a power supply device that is lit by DC power other than the LED element. In any of the embodiments, an auxiliary power supply device having the same configuration as that of the auxiliary power supply circuit 5 shown in the first embodiment is included. In the following description, the main configuration and operation of each switching circuit will be described. In addition, about the structure which is common in the previous embodiment, the same code | symbol is attached | subjected to a figure, and description is abbreviate | omitted.

Second Embodiment FIG. 2 shows a circuit configuration of a high-side switching step-down LED power supply according to a second embodiment. Unlike the switching circuit 6 of the first embodiment, in the step-down switching circuit 16 of the present embodiment, a switching element S1 is disposed between the positive electrode side of the full-wave rectifier 2 and the choke coil L1. In this case, the potential at the connection point (point P) between the switching element S1 and the choke coil L1 alternately changes between a high level and a low level. The auxiliary power supply circuit 5 is connected so that the potential at point P is applied. The other LED power supply circuit configuration is common to the circuit configuration of the first embodiment.

  The operation of the LED power supply will be briefly described. When ON, a conduction loop is formed from the positive side of the full-wave rectifier 2 to the switching element S1, the choke coil L1, the electrolytic capacitor C2, and the negative side of the full-wave rectifier 2, so that a rectified direct current is generated at the point P. A voltage is applied. On the other hand, at the time of OFF, the above-described conduction loop is cut, and a regenerative current flows from the choke coil L1 to the electrolytic capacitor C2 and the diode D1 in this order. The diode D1 is turned on with a potential difference of about 1 V in the rectifying direction. The potential of the anode (anode) of the diode D1 is conducted to the ground level. Therefore, the point P at the time of OFF in the circuit of FIG. 2 is almost zero volts (0V). In addition, to supplement the diode D1, the forward voltage Vf of the diode D1 (indicating the voltage flowing from P to N of the PN junction) increases as the current increases in the case of a general silicon diode. For example, it increases from 0.5V to 1.4V. Further, the forward voltage Vf is temperature dependent and slightly decreases as the temperature increases.

  As shown in FIG. 8, the time change of the voltage at point P becomes a high-level (voltage A) voltage waveform in the on state and a low level (voltage B) waveform in the off state. When the point P is at the high level, the potential A is divided by the series connection circuit of the voltage dividing capacitors C4 and C5 of the auxiliary power supply circuit 5, and thereafter, the electrolytic capacitor C5 is charged as in the first embodiment. The According to the configuration of the present embodiment, the same effect as in the first embodiment can be obtained.

Third Embodiment FIG. 3 shows a circuit configuration of a step-up LED power supply according to a third embodiment of the present invention. Except for the provision of the step-up switching circuit 26, it is common to the circuit configuration of the first embodiment.

  The step-up switching circuit 26 boosts and outputs the rectified voltage to a predetermined level, and is used as a power factor correction circuit or the like. Each circuit element is connected as shown in FIG. First, one end of the choke coil L1 is connected to the positive terminal of the full-wave rectifier 2, and the switching element S1 connects the other end of the choke coil L1 and the negative terminal of the full-wave rectifier 2. The anode side of the diode D1 is connected to the connection point between the choke coil L1 and the switching element S1. The positive electrode side of the electrolytic capacitor C2 is connected to the cathode side of the diode D1. The negative electrode side of the electrolytic capacitor C2 is connected to the negative electrode terminal of the full-wave rectifier 2. The LED light emitter 3 is connected between both terminals of the electrolytic capacitor C2. Thus, the voltage applied to the choke coil L1 is switched as the switching element S1 is driven.

  In the step-up switching circuit 26, the potential at the connection point (point P) between the choke coil L1 and the switching element S1 alternately changes between a high level and a low level. The auxiliary power supply circuit 5 is connected so that the potential at point P is applied.

  The operation of the LED power supply will be briefly described. When turned on, a conduction loop is formed from the positive side of the full-wave rectifier 2 to the choke coil L1, the switching element S1, and the negative side of the full-wave rectifier 2, and magnetic field energy is accumulated in the choke coil L1 by applying a rectified voltage. Is done. The potential at point P is approximately zero volts. On the other hand, at the time of OFF, the above-described conduction loop is cut, the point P changes to a high level, and a regenerative current accompanying the release of magnetic field energy from the choke coil L1 flows in the order of the diode D1, the electrolytic capacitor C2, and the capacitor C1. The potential at the point P becomes high level.

  Therefore, as shown in FIG. 7, the time change of the voltage at the point P becomes a high-level (voltage A) voltage waveform in the off state and a low level (voltage B) waveform in the on-state. When the point P is at the high level, the potential A is divided by the series connection circuit of the voltage dividing capacitors C4 and C5 of the auxiliary power supply circuit 5, and thereafter, the electrolytic capacitor C5 is charged as in the first embodiment. The

  According to the configuration of the present embodiment, the same effect as in the first embodiment can be obtained. Note that a continuous current mode (also referred to as an average current method) control method may be employed for the switching control of the boost switching circuit 26. In the continuous current mode, the power factor correction control can be executed with the switching frequency fixed to a predetermined set value. Therefore, the combination with the auxiliary power supply circuit 5 of the present embodiment prevents the fluctuation of the voltage of the electrolytic capacitor C3 because the switching frequency is fixed even when the power factor improvement control is executed with the on-duty variable. Can do.

Fourth Embodiment FIG. 4 shows a circuit configuration of an LED power source of a two-converter circuit combining a boosting method and a lifting method according to a fourth embodiment of the present invention.

  This LED power supply is provided with a step-down circuit 36 in the subsequent stage of the step-up switching circuit (step-up circuit) 26 based on the circuit configuration of the step-up LED power supply shown in FIG. The step-down circuit 36 has the same configuration as the step-down switching circuit 6 of FIG. The control circuit 4 controls driving of each switching element of the booster circuit 26 and the step-down circuit 36, and is supplied with auxiliary power from the auxiliary power supply circuit 5 charged by the potential at the point P in the booster circuit 26. Yes. According to this embodiment, the same effect as the third embodiment can be obtained.

Fifth Embodiment FIG. 5 shows a circuit configuration of a buck-boost LED power source according to a fifth embodiment of the present invention. The circuit configuration of the first embodiment is the same as that of the first embodiment except that a step-up / step-down switching circuit 46 is provided instead of the step-down switching circuit 6.

  Each step-up / down switching circuit 46 is connected to each circuit element as shown in FIG. First, one end of the choke coil L1 is connected to the positive terminal of the full-wave rectifier 2, and the switching element S1 connects the other end of the choke coil L1 and the negative terminal of the full-wave rectifier 2. The anode side of the diode D1 is connected to the connection point between the choke coil L1 and the switching element S1. The positive electrode side of the electrolytic capacitor C2 is connected to the cathode side of the diode D1. The negative electrode side of the electrolytic capacitor C2 is connected to the positive electrode terminal of the full-wave rectifier 2. The LED light emitter 3 is connected between both terminals of the electrolytic capacitor C2. Thus, the voltage applied to the choke coil L1 is switched as the switching element S1 is driven.

  In the step-up / step-down switching circuit 46, the potential at the connection point (point P) between the choke coil L1 and the switching element S1 alternately changes between a high level and a low level. The auxiliary power supply circuit 5 is connected so that the potential at point P is applied.

  The operation of the LED power supply will be briefly described. When turned on, a conduction loop is formed from the positive side of the full-wave rectifier 2 to the choke coil L1, the switching element S1, and the negative side of the full-wave rectifier 2, and magnetic field energy is accumulated in the choke coil L1 by applying a rectified voltage. Is done. The potential at point P is approximately zero volts. On the other hand, at the time of OFF, the above-described conduction loop is cut, and the regenerative current accompanying the release of magnetic field energy from the choke coil L1 flows in the order of the diode D1 and the electrolytic capacitor C2, and returns to the choke coil L1. The potential at point P becomes high level due to the flow of regenerative current.

  Therefore, as shown in FIG. 7, the time change of the voltage at the point P becomes a high-level (voltage A) voltage waveform in the off state and a low level (voltage B) waveform in the on-state. When the point P is at the high level, the potential A is divided by the series connection circuit of the voltage dividing capacitors C4 and C5 of the auxiliary power supply circuit 5, and thereafter, the electrolytic capacitor C5 is charged as in the first embodiment. The According to the configuration of the present embodiment, the same effect as in the first embodiment can be obtained.

Sixth Embodiment FIG. 6 shows a circuit configuration of a flyback LED power supply according to a sixth embodiment of the present invention. This LED power supply employs the auxiliary power supply circuit of the first embodiment in an insulated one converter. The circuit configuration is the same as that of the first embodiment except that a flyback switching circuit 56 is provided instead of the step-down switching circuit 6.

  Each circuit element of the switching circuit 56 is connected as shown in FIG. First, a series circuit of a primary coil of a flyback transformer T and a switching element S <b> 1 is connected between terminals of the full-wave rectifier 2. The transformer T corresponds to the inductance element of the present invention. A series circuit of a diode D1 and an electrolytic capacitor C2 is connected to the secondary coil of the transformer T. The LED light emitter 3 is connected between both terminals of the electrolytic capacitor C2. Note that the negative electrode terminal of the electrolytic capacitor C2 is electrically connected to the ground line. Thus, the voltage applied to the primary coil of the transformer T is switched as the switching element S1 is driven.

  In the switching circuit 56, the potential at the connection point (point P) between the primary coil of the transformer T and the switching element S1 alternately changes between a high level and a low level. The auxiliary power supply circuit 5 is connected so that the potential at point P is applied.

  The operation of the flyback LED power supply will be briefly described with reference to FIG. When turned on, a conduction loop is formed from the positive side of the full-wave rectifier 2 to the primary coil of the transformer T, the switching element S1, and the negative side of the full-wave rectifier 2, and a magnetic field is applied to the primary coil of the transformer T by application of the rectified voltage. Energy is accumulated. The potential at point P at this time is approximately zero volts. On the other hand, at the time of OFF, the above-described conduction loop is cut off, and a current accompanying the release of magnetic field energy from the secondary coil of the transformer T flows in the order of the diode D1 and the electrolytic capacitor C2, and returns to the secondary coil of the transformer T. At this time, the potential at the point P becomes a high level.

  Therefore, as shown in FIG. 7, the time change of the voltage at the point P becomes a high-level (voltage A) voltage waveform in the off state and a low level (voltage B) waveform in the on-state. When the point P is at the high level, the potential A is divided by the series connection circuit of the voltage dividing capacitors C4 and C5 of the auxiliary power supply circuit 5, and thereafter, the electrolytic capacitor C5 is charged as in the first embodiment. The According to the configuration of the present embodiment, the same effect as in the first embodiment can be obtained.

1 AC power supply 2 Full-wave rectifier 3 LED light emitter (or LED lighting fixture)
4 Control circuit 5 Auxiliary power circuit 6, 16, 26, 36, 46, 56 Switching circuit C2 Electrolytic capacitor (DC power supply capacitor)
C3 Electrolytic capacitor (capacitor for auxiliary power supply)
C4, C5 voltage dividing capacitor D2 diode (rectifier for discharge limitation)
D3 diode (rectifier for positive charge replenishment)
L1 Choke coil (inductance element)
S1 Switching element T Flyback transformer (inductance element)

Claims (4)

An inductance element to which an input voltage of a rectified voltage or a DC voltage is supplied;
A switching element that switches a voltage between terminals of the inductance element; and
A capacitor for a direct current power source charged by a positive charge generated as a result of accumulating and releasing magnetic field energy in the inductance element;
A power supply apparatus for supplying an output voltage due to the positive charge accumulated in the DC power supply capacitor, and
A control circuit for driving the switching element, and an auxiliary power circuit for operating the control circuit,
The auxiliary power circuit has an auxiliary power capacitor,
The positive terminal of the auxiliary power supply capacitor is connected to the potential fluctuation side terminal on the side where the potential fluctuates between the high level and the low level in accordance with the driving of both terminals of the switching element,
The auxiliary power supply capacitor is charged with a positive charge from the potential fluctuation side terminal of the switching element, and supplies a DC voltage based on the accumulated positive charge to the control circuit ,
The auxiliary power circuit further includes a voltage dividing circuit that connects between the potential variation side terminal of the switching element and a ground line,
Wherein the auxiliary power supply capacitor, the power supply potential level after the division by the dividing circuit and wherein Rukoto applied. The power supply device according to claim 1 , wherein
The voltage dividing circuit is a series connection circuit of a plurality of voltage dividing capacitors. The power supply device according to claim 2 , wherein
The auxiliary power circuit includes a discharge limiting rectifier element that connects a potential level after voltage division by the series connection circuit and a positive terminal of the auxiliary power capacitor,
The discharge limiting rectifying element is connected in a direction to limit the discharge of the positive charge accumulated in the auxiliary power supply capacitor. The power supply device according to claim 2 or 3 ,
The auxiliary power supply circuit has a rectifying element for replenishing positive charges connecting the potential level after voltage division by the series connection circuit and the ground line,
The power supply apparatus according to claim 1, wherein the positive charge replenishing rectifier element is connected in a direction to replenish positive charges from the ground line to a potential level point after voltage division of the voltage dividing circuit.

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