JP2011186583A - Circuit device and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem that electromotive force (output voltage) becomes low, and driving of the load becomes difficult, when a plurality of solar batteries are serially connected to increase an output voltage, to accumulate electricity via a backflow prevention diode in a secondary battery, and to supply power to a load via a voltage stabilization circuit, and when the quantity of light to be emitted to the solar battery is small. <P>SOLUTION: A voltage conversion circuit 102 (boosting circuit) is driven according to the output of a controller 101 so that the operating point of a solar battery PV can be held at an operating point where its output efficiency is highly held. Since the solar battery PV is operated at the operating point where its output efficiency is high, it is possible to hold the output voltage even when the quantity of light is small (output voltage is low), and it is possible to stably drive a load. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a circuit device and an electronic apparatus.

  A solar cell is an element that converts light into electric power. When a solar cell is used in an electronic device, it can supply power cordlessly, and thus is particularly suitable for an electronic device for mobile use. Here, since the output of the solar cell depends on the intensity of irradiated light, a solar cell provided with a secondary battery for backup has been proposed.

  FIG. 6 is a circuit block diagram showing the background art when a secondary battery is provided for backup. As shown in FIG. 6, the output voltage is increased by connecting a plurality of solar cells PV in series, and the secondary battery 11 is charged via the reverse current blocking diode 10 and loaded via the voltage stabilizing circuit 12. Techniques for supplying power to 13 are known.

  Patent Document 1 discloses a technique for storing power in a secondary battery (battery) via a backflow prevention diode with a DC / DC converter for maximizing the power generated by the solar battery (MPPT: Maximum Power Point Tracker). Has been.

JP-A-6-266454

  However, when the above-described technology is used, when the amount of light applied to the solar cell is small, there is a problem that the electromotive force (output voltage) becomes low, and it becomes difficult to drive the load or charge the secondary battery. is there. Further, the reverse current blocking diode has a voltage drop in the forward direction of about 0.5 V, depending on the current value, and generates a voltage drop similar to the power generation voltage of one solar cell.

In this case, it is necessary to connect the solar cells in series and increase the output voltage. However, a part of the cells of the solar cells connected in series (for example, one of ten cells in series) is irradiated. When the amount of light to be reduced (partial shadow), the current that can be supplied by the cell becomes small. For this reason, there is a problem that the current flowing through the other cell is reduced to a current that can be passed through the cell, and the photoelectric conversion efficiency is lowered. In addition, when solar cells are connected in series, there is a problem that design restrictions occur when they are mounted in a limited space of an electronic device. In addition, since it is necessary to divide and divide the areas of the solar cells to the same extent, there is a problem that power generation cannot be performed in the region of the gap between the divided solar cells, and the generated power is reduced.
In addition, when the state in which the amount of light applied to the solar cell is small continues, there is a problem that the power stored in the secondary battery is reduced and the driving of the load becomes difficult.
In addition, if the amount of light applied to the solar cell is too large, the output voltage rises excessively, and there is a problem that it exceeds the rated voltage of a device such as a voltage stabilization circuit connected to the output of the solar cell. .

  Moreover, as shown in Patent Document 1, when the output of the solar cell is modulated and connected so as to be electrically in parallel with the power system, there is a problem that a connection electric wire is required and portability is reduced.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  Application Example 1 A circuit device according to this application example includes a first circuit and a second circuit, and the first circuit is based on at least one of an output voltage or an output current of a solar cell. The operating point of the solar cell is determined, the first circuit controls the second circuit, the solar cell operates at the operating point, and the second circuit outputs power from the solar cell. Features.

  According to this, the operating point of the solar cell is determined by the first circuit, the second circuit is controlled by the first circuit, and electric power is output from the solar cell via the second circuit. By controlling the operating point, the values of voltage, current, and power can be varied, so that it is possible to cope with various applications. Moreover, since it is not necessary to connect solar cells in series, it is possible to suppress the influence of partial shadows.

  Application Example 2 In the circuit device according to the application example described above, the second circuit controls the operating point by pulse modulation control. Specifically, the pulse modulation control performs PFM control that thins out the generation of pulses when the illuminance is indoors or the like, and performs PWM control that makes the pulse width variable during normal times such as outdoors or during high illuminance.

  According to the application example described above, in principle, pulse modulation can control the operating point without any power loss. In addition, since the pulse modulation control can be designed for both step-up and step-down, it is possible to cope with various applications.

  Application Example 3 A circuit device according to the application example described above, wherein a third circuit is provided between the second circuit and the power storage device, and the third circuit supplies a charging current supplied to the power storage device to the power storage device. It is limited within the rated range of the power storage device.

  According to the application example described above, the charging current can be supplied without exceeding the rating of the power storage device, so that the power storage device can be charged without deteriorating. By providing the power storage device, it is possible to supply stable power as compared to the case where there is no power storage device.

  Application Example 4 In the circuit device according to the application example described above, a fourth circuit is provided at an output terminal of the second circuit, and the fourth circuit stabilizes a voltage output from the second circuit. It is characterized by.

  According to the application example described above, it is possible to reduce the instability of the power supplied from the solar cell and supply a stable voltage.

  Application Example 5 In the circuit device according to the application example described above, the second circuit includes an inductor having one end connected to the solar cell and a portion having the other end of the inductor and a first potential. And a diode having one end connected between the other end of the inductor and the output terminal of the second circuit, and the transistor is subjected to pulse modulation control by the first circuit. And

  According to the application example described above, in principle, the pulse modulation control can control the operating point without power loss. In this case, the booster circuit can be configured with a small number of parts.

  Application Example 6 In the circuit device according to the application example described above, a first capacitor connected between the other end of the diode and a region having the first potential, or the other end of the inductor , Further comprising at least one of a second capacitor connected between the first potential portion and the portion having the first potential.

  According to the application example described above, it is possible to obtain a configuration in which the pulse modulation control outputs a lower ripple content than in the case where the first capacitor or the second capacitor is not provided.

  Application Example 7 A circuit device according to this application example includes a first circuit and a second circuit, and the first circuit is based on at least one of an output voltage or an output current of a solar cell, and An operating point of a solar cell is determined, the first circuit controls the second circuit, the solar cell operates at the operating point, and the second circuit outputs electric power from the solar cell. And

  According to this, since the voltage value and the current value can be changed independently of the amount of light applied to the solar cell, it is possible to provide an electronic device that operates stably even when the amount of light varies.

  Application Example 8 In the circuit device according to the application example described above, the second circuit is provided between an inductor having one end connected to the solar cell, and a portion having the other end of the inductor and a first potential. And a diode having one end connected between the other end of the inductor and the output terminal of the second circuit, and the transistor is subjected to pulse modulation control by the first circuit. And

  According to the application example described above, in principle, the pulse modulation control can control the operating point without power loss. In this case, the booster circuit can be configured with a small number of parts.

  Application Example 9 In the circuit device according to the application example described above, the first capacitor connected between the other end of the diode and the region having the first potential, or the other end of the inductor , Further comprising at least one of a second capacitor connected between the first potential portion and the portion having the first potential.

  According to the application example described above, it is possible to obtain a configuration in which the pulse modulation control outputs a lower ripple content than in the case where the first capacitor or the second capacitor is not provided.

  Application Example 10 An electronic apparatus according to this application example includes the circuit device described above.

  According to this, since the voltage value and the current value can be changed independently of the amount of light applied to the solar cell, it is possible to provide an electronic device that operates stably even when the amount of light varies.

1 is a block diagram showing a configuration of a circuit device according to a first embodiment. (A)-(c) is a circuit diagram which shows the basic composition of a voltage converter circuit. (A)-(c) is the schematic of the electronic device containing a circuit apparatus. The block diagram which shows the structure of the circuit device in 2nd Embodiment. The block diagram which shows the structure of the circuit device in 3rd Embodiment. The block diagram of the circuit which shows background art.

  Hereinafter, preferred embodiments of the present invention will be described in detail. The present embodiment described below does not unduly limit the contents of the present invention described in the claims, and all the configurations described in the present embodiment are indispensable as means for solving the present invention. Not always.

(First embodiment)
The first embodiment will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration of a circuit device according to the present embodiment. The circuit device 100 includes a solar battery PV, a controller 101, a voltage conversion circuit 102, a charge / discharge control circuit 103, a charge storage device 104, and a voltage stabilization circuit 105. Then, electric power is supplied to the electronic circuit 200 via the voltage stabilization circuit 105 provided in the circuit device 100.
The solar cell PV has a positive terminal (anode terminal) connected to the controller 101, determines an operating point based on at least one of the output voltage or output current of the solar cell PV, and performs pulse width modulation control pulses. Is supplied to the voltage conversion circuit 102.

The voltage conversion circuit 102 receives a control signal from the controller 101, converts the voltage so as to keep the operating point of the solar cell PV at the above-described operating point, and outputs the converted voltage. A typical configuration of the voltage conversion circuit 102 will be described later.
The charge storage device 104 stores power when the power received from the solar cell PV is larger than the power supplied to the electronic circuit 200, and discharges to balance the power when the power is smaller.

  The charge / discharge control circuit 103 controls the current flowing into and out of the charge storage device 104. In particular, when a lithium ion battery having an excellent electric capacity per volume is used for the charge storage device 104, it is preferable to protect the charge storage device 104 by the charge / discharge control circuit 103 in order to avoid overcharge and overdischarge. is there.

  The voltage stabilization circuit 105 stabilizes the voltage output to the electronic circuit 200 serving as a load. As a specific configuration, a drop type series regulator or a switching regulator configuration by PWM modulation can be used. Regarding the power utilization efficiency, it is preferable to use a switching regulator. When the electronic circuit 200 has low noise resistance, it is preferable to use a drop type series regulator rather than a switching regulator.

Next, the operation of the circuit device 100 will be described.
When the generated power of the solar cell PV is larger than the power consumed by the electronic circuit 200 and the charge storage device 104 can be charged, the controller 101 follows the operating point that can keep the output efficiency of the solar cell PV high (MPPT : Maximum Power Point Tracking: Maximum power point tracking) to drive the voltage conversion circuit 102. The MPPT method is not particularly limited, but the so-called hill-climbing method, in which power is measured at three points and the maximum power point is searched, or about 60% to 85% of the open-circuit voltage (depending on the structure of the solar cell PV) It is possible to use a voltage follow-up method that adjusts the voltage so that In this case, the charge storage device 104 is charged via the charge / discharge control circuit 103, and the stabilized voltage is supplied to the electronic circuit 200 via the voltage stabilization circuit 105.

  Next, when the generated power of the solar battery PV is larger than the power consumed by the electronic circuit 200 and the charge storage device 104 is fully charged, the charge / discharge control circuit 103 sends the controller 101 to the solar battery PV from the solar battery PV. Control to cut off power. When the electronic circuit 200 operates in this state, the voltage conversion circuit 102 is controlled so that the output voltage of the voltage conversion circuit 102 (input voltage to the voltage stabilization circuit 105) does not exceed the maximum rated voltage of the voltage stabilization circuit 105. The operation is done.

Next, when the generated power of the solar cell PV is smaller than the power consumed by the electronic circuit 200 and the charge storage device 104 is charged, the controller 101 is set to an operating point that increases the output efficiency of the solar cell PV. Then, the voltage output from the voltage stabilization circuit 105 is kept constant by supplying the insufficient power from the charge storage device 104 via the charge / discharge control circuit 103. If power cannot be taken out from the charge storage device 104, the output voltage is lowered to drive the electronic circuit 200. Or shut off the output.
Here, the charge storage device 104 and the charge / discharge control circuit 103 are not essential and can be omitted. When the generated power of the solar cell PV is smaller than the power consumed by the electronic circuit 200, the controller 101 sets the operating point at the maximum power point of the solar cell PV, and the voltage output from the voltage stabilization circuit 105 is set. Operates to maintain maximum.

  In addition, when the generated power of the solar battery PV is larger than the power consumed by the electronic circuit 200, the controller 101 extracts the power with reduced efficiency from the voltage conversion circuit 102, and the supplied power and output It is operated so as to be matched with the electric power (so that the output voltage of the voltage conversion circuit 102 does not exceed the maximum rated voltage of the voltage stabilization circuit 105). When a drop-type series regulator is used for the voltage stabilization circuit 105, power is consumed by the voltage stabilization circuit 105 so that the supplied power and the output power are matched. May be. Alternatively, a combination of these may be operated so as to match the supplied power and the output power. Further, depending on the configuration of the electronic circuit 200, a current stabilization circuit may be used instead of the voltage stabilization circuit 105.

  In addition, in the case where an electric double layer capacitor or a device strong against overcharge, such as a lead storage battery, is used as the charge storage device 104, the charge / discharge control circuit 103 is not an essential configuration and is omitted. Is possible. When the electronic circuit 200 is resistant to voltage fluctuation, the voltage stabilizing circuit 105 is not an essential configuration and can be omitted. As described above, the charge storage device 104, the charge / discharge control circuit 103, and the voltage stabilization circuit 105 can be omitted independently. In addition to the reasons described above, for example, in addition to cost problems, reduction in the number of parts, and space saving, the elements described above can be omitted without any special reason.

Moreover, the solar cell PV does not need to accompany the circuit device 100, and may be operated by receiving power from a separately installed solar cell. In this case, the circuit device 100 can be handled as a configuration that does not include the solar cell PV.
Further, the solar cells PV may be connected in series. Even in this case, since the voltage can be boosted by using the voltage conversion circuit 102, the number of solar cells PV connected in series can be reduced. For this reason, the probability that a part of the solar cell PV is shaded is reduced, so that it is possible to suppress a decrease in output current.

  Next, the configuration of the voltage conversion circuit 102 will be described. For the voltage conversion circuit 102, for example, PFM control that thins out the generation of pulses when the illuminance is indoors or the like, and PWM control that makes the pulse width variable at normal or high illuminance such as outdoors, so as to suit the sunshine conditions. Pulse modulation control is preferably used. FIG. 2A is a circuit diagram showing the basic configuration of the voltage conversion circuit when the cathode side of the solar cell PV is used as the first potential. When a solar cell PV that does not use a diode structure is used, the negative voltage output side is used as the first potential. FIG. 2B is a circuit diagram when a positive potential (anode side) is used as the first potential. When the solar cell PV not using the diode structure is used, the side that outputs a positive voltage is used as the first potential. FIG. 2C is a circuit diagram showing a basic configuration as a voltage conversion circuit that outputs a negative voltage when the cathode side is used as the first potential. As the power source, an example using a solar cell PV is described. Here, the voltage conversion circuit 102 uses the negative potential side of the solar battery PV as the ground potential as the first potential, the input capacitor 150 as the first capacitor, the inductor 151, the freewheel diode 152, and the output as the second capacitor. A case where the capacitor 153 and the switching transistor 154 are used will be described.

The current supplied from the solar cell PV is first stored in the input capacitor 150. Here, the input capacitor 150 is not an essential element and can be omitted.
The inductor 151 is connected to one end of the solar cell PV, and is connected to one end of the freewheel diode 152 and one end of the switching transistor 154 at the other end. The other end of the switching transistor 154 is connected to the ground potential. The switching transistor 154 receives a signal for determining the pulse width from the controller 101 (see FIG. 1) and adjusts the pulse width.
The other end of the freewheeling diode 152 is connected to a load (not shown) (for example, the voltage stabilizing circuit 105), and has a function of returning the current flowing through the inductor 151.
The output capacitor 153 is connected between the other end of the freewheel diode 152 and the ground potential, and accumulates and smoothes the current supplied from the freewheel diode 152. Here, the output capacitor 153 is not an essential component and can be omitted.

Next, the operation of the voltage conversion circuit 102 will be described with reference to FIG. Here, a case where the input capacitor 150 and the output capacitor 153 are included will be described. First, the initial state is a state in which the switching transistor 154 is cut off. In addition, the current supplied from the solar cell PV is assumed to be accumulated in the input capacitor 150. The switching transistor 154 is short-circuited according to the pulse width sent from the controller 101 (see FIG. 1) set to be an operating point determined based on at least one of the output voltage or the output current of the solar cell PV. And In this state, the current flowing through the inductor 151 increases as the pulse width increases. Then, the power flow from the solar cell PV is accumulated in the inductor 151. Thereby, the output power pressure of the solar cell PV is controlled.
Next, when the supply of the pulse is finished (when the switching transistor 154 is opened), the current accumulated in the inductor 151 is charged to the output capacitor 153 via the freewheel diode 152. By this operation, the output potential rises and is supplied to a load (not shown) (for example, voltage stabilization circuit 105: see FIG. 1).
By repeating this operation, the output power of the solar cell PV can be controlled. By expanding the pulse width, the output voltage of the solar cell PV decreases, and by decreasing the pulse width, the output voltage of the solar cell PV increases. That is, the operating point can be controlled.

Next, the voltage conversion circuit 102 shown in FIG. Since FIG. 2 (b) has a configuration similar to that of FIG. 2 (a), differences will be mainly described. The main difference is that the anode of the solar cell PV is used as the first potential, the direction of the free wheel diode 152 is opposite, and a PMOS transistor is used as the switching transistor 154. . In this case, a configuration in which the positive potential side of the solar cell PV is grounded as the first potential is provided.
In this case, the current flows in the opposite direction to that described above. The switching transistor 154 performs switching in response to a negative voltage pulse. And the output voltage of the solar cell PV can be controlled by the same operation. By expanding the pulse width, the absolute value of the output voltage of the solar cell PV decreases, and by decreasing the pulse width, the absolute value of the output voltage of the solar cell PV increases. That is, the operating point can be controlled.

Next, the voltage conversion circuit 102 shown in FIG. When a positive and negative power supply is required as a load (not shown), it is preferable to further include this voltage conversion circuit 102.
The current supplied from the solar cell PV is first stored in the input capacitor 150. Here, the input capacitor 150 is not an essential element and can be omitted.
One end of the switching transistor 154 is connected to one end of the solar cell PV, and the other end is connected to one end of the freewheel diode 152 and one end of the inductor 151. The other end of the inductor 151 is connected to the ground potential. The output capacitor 153 is connected between the other end of the freewheel diode 152 and the ground potential, and accumulates and smoothes the current supplied from the freewheel diode 152. Here, the output capacitor 153 is not an essential component and can be omitted.
Next, the operation of the voltage conversion circuit 102 will be described with reference to FIG. Here, a case where the input capacitor 150 and the output capacitor 153 are included will be described. First, the initial state is a state in which the switching transistor 154 is cut off.
In addition, the current supplied from the solar cell PV is assumed to be accumulated in the input capacitor 150. Here, according to the pulse width sent from the controller 101 (see FIG. 1), the switching transistor 154 is brought into a short-circuited state for the time during which the pulse is applied. In this state, the current flowing through the inductor 151 increases as the pulse width increases.
Next, when the supply of the pulse is finished (when the switching transistor 154 is opened), the current flowing through the inductor 151 is charged to the output capacitor 153 via the freewheel diode 152. Since the current flows from the ground side of the output capacitor 153 to the freewheel diode 152 side, a negative voltage is generated at the load side terminal of the output capacitor 153. By this operation, the absolute value of the output potential increases (decreases as the potential) and is supplied to a load (not shown).
In the above description, the potential on one side of the solar cell PV is used as the first potential. However, for example, an intermediate potential of the solar cell PV or another potential may be used. Moreover, when mainly using a negative voltage output, the operating point of the solar cell PV may be determined by the voltage conversion circuit 102 shown in FIG.

(Electronics)
Hereinafter, electronic devices including the circuit device 100 described above will be exemplified. 3A, 3B, and 3C are schematic views of an electronic device including a circuit device. 3A shows the front side (display side) of the digital photo frame 171, and FIG. 3B shows the back side (side with the circuit device). The digital photo frame 171 includes a display unit 171a (corresponding to the electronic circuit 200) on the front surface and a circuit device 100 including a solar cell PV on the back surface.
FIG. 3C is a plan view showing the solar charging device 177. In this case, the solar cell PV has a configuration corresponding to the switching of the circuit device 100 by replacing the input connector 175 with respect to the solar cell PV having a different area because of power generation capacity and cost. That is, the circuit device 100 and the solar cell PV have a separated configuration. Then, the electric power supplied from the solar cell PV to the output connector 176 is supplied to the electronic circuit 200 via the circuit device 100. As the electronic circuit 200, here, a storage battery is illustrated and charged.

  Hereinafter, the effect by using 1st Embodiment and an electronic device is demonstrated.

  Since the voltage of the solar cell PV can be boosted by the voltage conversion circuit 102, it is possible to effectively extract power even when the output voltage of the solar cell PV is small.

  Since the solar cells PV are not connected in series or a small number of solar cells PV are connected in series to extract electric power, it is possible to suppress a decrease in power generation efficiency due to partial shadows.

  Since it becomes possible to supply electric power without making a large number of solar cells PV in series, design constraints can be reduced (or eliminated).

  Since it becomes possible to supply electric power without making a large number of solar cells PV in series, it is possible to reduce the gap by reducing (or eliminating) the number of divisions of the solar cells PV, thereby reducing the area of the solar cells PV. It becomes possible to take large.

  When the charge storage device 104 is in a chargeable state, the controller 101 drives the voltage conversion circuit 102 by following an operating point (MPPT: maximum power point tracking) that can keep the output efficiency of the solar cell PV high. This increases the charging time and the operating time of the electronic circuit 200.

  By providing the charge / discharge control circuit 103, it is possible to use, for the charge storage device 104, a lithium ion battery that has a large capacity but requires precise charge / discharge control.

  Since the voltage stabilization circuit 105 is provided, the voltage applied to the electronic circuit 200 can be kept constant, and the electronic circuit 200 can be driven in a stable state.

  By providing the charge storage device 104, the voltage applied to the electronic circuit 200 can be kept constant even when the intensity of light applied to the solar cell PV is unstable, and the electronic circuit 200 is driven in a stable state. be able to.

  Even when the intensity of light irradiated to the solar cell PV is strong, the controller 101 intentionally reduces the conversion efficiency of the voltage conversion circuit 102 (for example, by shortening the pulse width of PWM control) to the electronic circuit 200. The applied voltage can be kept constant, and the electronic circuit 200 can be driven in a stable state.

  When a device that is strong against overcharge and overdischarge, such as an electric double layer capacitor or a lead storage battery, is used for the charge storage device 104, the charge / discharge control circuit 103 can be omitted, and the circuit scale is reduced. It becomes possible to do.

  Voltage conversion can be efficiently performed by using the PFM control that thins out the generation of pulses in the voltage conversion circuit 102 and the pulse modulation control that performs the PWM control that makes the pulse width variable according to the sunshine conditions.

  By using the above-described pulse modulation control, basically, boosting can be performed with only the inductor 151, the free wheeling diode 152, and the switching transistor 154, and a boosting circuit can be configured with only a small number of components.

  Since the voltage conversion circuit 102 has the function of a backflow prevention diode, the backflow prevention diode can be omitted.

  By providing at least one of the input capacitor 150 and the output capacitor 153, it is possible to boost the voltage while suppressing ripples.

  Since the voltage conversion circuit can generate a negative voltage, it is possible to drive the analog electronic circuit 200 that requires positive and negative voltages.

  By configuring the digital photo frame 171 including the circuit device 100 and the solar charging device 177, the digital photo frame 171 and the solar charging device 177 can be driven cordlessly. In particular, when power consumption is reduced by using a digital photo frame 171 to which a reflective liquid crystal device is applied, the digital photo frame 171 can maintain stable display quality when used in a bright environment.

  By enabling the solar battery PV to be switched by the input connector 175 as the solar battery charger 177, it is possible to provide the solar battery charger 177 that can meet the demands for cost and power generation.

(Second Embodiment)
The second embodiment will be described below with reference to the drawings. FIG. 4 is a block diagram showing the configuration of the circuit device according to the present embodiment. The circuit device 100 includes a solar cell PV, a controller 101, a voltage conversion circuit 102, a charge / discharge control circuit 103, a charge storage device 104, a voltage stabilization circuit 105, a power supply switching device 106, and an external power supply device 107. Then, electric power is supplied to the electronic circuit 200 via the voltage stabilization circuit 105 provided in the circuit device 100.
Since the configuration excluding the power supply switching device 106 and the external power supply device 107 conforms to the first embodiment described above, a description thereof will be omitted to avoid duplication of description.

  When the power input from the solar battery PV decreases and the power stored in the charge storage device 104 decreases, the power supply switching device 106 switches to the external power supply device 107 and drives the electronic circuit 200 serving as a load. There may be a plurality of external power supply devices 107, and the controller 101 switches the external power supply devices 107 according to the priority order. As the external power supply device 107, for example, a commercial power supply converted using an AC-DC converter or a USB power supply can be used.

  Next, the operation of the circuit device 100 will be described. When the generated power of the solar cell PV is larger than the power consumed by the electronic circuit 200 and the charge storage device 104 can be charged, the generated power of the solar cell PV is larger than the power consumed by the electronic circuit 200, The case where the charge storage device 104 is fully charged and the case where the generated power of the solar cell PV is smaller than the power consumed by the electronic circuit 200 and the charge storage device 104 is charged are the same as described above. Perform the process. In this state, the power supply switching device 106 keeps the voltage conversion circuit 102, the charge / discharge control circuit 103, and the voltage stabilization circuit 105 connected.

  When the generated power of the solar cell PV is smaller than the power consumed by the electronic circuit 200 and power cannot be taken out from the charge storage device 104, an operation different from the above case is performed. In this case, the information on the voltage and current of the solar cell PV input from the solar cell PV to the controller 101 and the signal sent from the charge / discharge control circuit 103 are received, and a power source switching signal is sent to the power source switching device 106. The power supply switching device 106 switches the external power supply device 107 in accordance with the priority order according to the signal received from the controller 101 and drives the electronic circuit 200. At this time, an operation of charging the charge storage device 104 via the charge / discharge control circuit 103 may be performed.

  Here, the charge storage device 104 and the charge / discharge control circuit 103 are not essential and can be omitted.

  When the generated power of the solar cell PV is smaller than the power consumed by the electronic circuit 200, an operation different from the above case is performed. In this case, information sent from the solar cell PV to the controller 101 is received, and a power switching signal is sent to the power switching device 106. The power supply switching device 106 switches the external power supply device 107 in accordance with the priority order according to the signal received from the controller 101 and drives the electronic circuit 200.

  Also in this case, the solar cell PV does not have to be attached to the circuit device 100, and may be operated by receiving power from a separately installed solar cell. In this case, the circuit device 100 can be handled as a configuration that does not include the solar cell PV. Also in this case, the solar cells PV may be connected in series.

  Hereinafter, the effect produced by using the second embodiment will be described.

  You may provide the structure which connected the solar cell PV in series. By using the configuration in which the solar cells PV are connected in series, the same power can be handled with a higher voltage, that is, a lower current than in the case where the solar cells PV are connected in parallel. Since the current output from the solar cell PV can be reduced, the current flowing through the control transistor also decreases. Therefore, since the contribution of the parasitic resistance of the control transistor can be reduced, the conversion efficiency of the voltage conversion circuit 102 can be increased. Even in this case, since the voltage can be boosted by using the voltage conversion circuit 102, the number of solar cells PV connected in series can be reduced. For this reason, the probability that a part of the solar cell PV is shaded is reduced, so that it is possible to suppress a decrease in output current.

  With the external power supply device 107 and the power supply switching device 106 (both see FIG. 4), the electronic circuit 200 can be driven even when light is not irradiated for a long time.

(Third embodiment)
Hereinafter, a third embodiment will be described with reference to the drawings. FIG. 5 is a block diagram showing the configuration of the bypass device according to the present embodiment. The bypass device 190 is connected to a power generation unit 180 that connects solar cells PV in series. The bypass device 190 includes a comparator 179 that detects a voltage generated by the solar cell PV and outputs a comparison result, and a switch 178 that controls conduction / shutoff according to the comparison result, and transmits power to the circuit device 100 described above.

When the power generation unit 180 in which the solar cells PV are connected in series has an imbalance in the output voltage of the solar cells PV due to the influence of shade or dirt (when the power generation capacity decreases, the output voltage of the solar cells PV increases) Then, the output of the comparator 179 is inverted, and the switch 178 is short-circuited. In this case, the comparator 179 has an offset voltage. For example, when a silicon solar cell PV is used, a voltage of about 0.5 V to 0.7 V (a value exceeding the normal output voltage of the solar cell PV) is applied. It is preferable to invert the output of the comparator 179. Further, the offset voltage may be determined based on the output voltage of the power generation unit 180. In this case, the switch 178 can be short-circuited at an earlier time point than when a fixed threshold value is used, and the power generation efficiency can be kept high.
Here, a transistor is preferably used as the switch 178.

  Here, when the solar cell PV is short-circuited, the output voltage from the power generation unit 180 decreases, but the circuit device 100 includes a booster (voltage conversion circuit 102, see FIG. 1). Fluctuations are mitigated.

  In this case, the bypass device 190 may include a configuration coupled to at least one of the power generation unit 180 and the circuit device 100.

  Hereinafter, effects produced by using the third embodiment will be described.

  With the external power supply device 107 and the power supply switching device 106 (both see FIG. 4), the electronic circuit 200 can be driven even when light is not irradiated for a long time.

  In the case of an imbalance in the output voltage of the solar cell PV due to the influence of shade and dirt (when the power generation capacity is reduced, the output voltage of the solar cell PV) When the switch 178 is short-circuited, a decrease in power generation efficiency of the power generation unit 180 can be suppressed.

  By determining the offset voltage based on the output voltage of the power generation unit 180, the switch 178 can be short-circuited at an earlier time point than when a fixed threshold value is used, and the power generation efficiency can be kept high.

  By using a transistor for the switch 178, the life can be extended as compared with the case where a mechanical relay is used.

  Since the circuit device 100 is provided with a booster (voltage conversion circuit 102, see FIG. 1), voltage fluctuation caused by short-circuiting the solar cell PV in the portion corresponding to the partial shadow is suppressed. As a result, fluctuations in the output voltage are alleviated and the influence on the operation of the electronic circuit 200 can be suppressed.

  By providing the bypass device 190 with a configuration coupled to at least one of the power generation unit 180 and the circuit device 100, the bypass device 190 can be adjusted in accordance with the characteristics of the solar cell PV and the characteristics of the circuit device 100. Become.

  Although the present embodiment has been described in detail as described above, it will be easily understood by those skilled in the art that many modifications can be made without departing from the novel matters and effects of the present invention. Accordingly, all such modifications are intended to be included in the scope of the present invention. For example, in the specification or drawings, terms (MPPT, PWM, etc.) described at least once together with different terms (maximum power point tracking, pulse width modulation) in a broader sense or the same meaning are used anywhere in the specification or drawings. Can be replaced by its different terms. Further, the configuration and operation of the voltage conversion circuit, the electronic device, and the like are not limited to those described in this embodiment, and various modifications can be made.

  PV ... solar cell, 10 ... reverse current blocking diode, 11 ... secondary battery, 12 ... voltage stabilization circuit, 13 ... load, 100 ... circuit device, 101 ... controller, 102 ... voltage conversion circuit, 103 ... charge / discharge control circuit, DESCRIPTION OF SYMBOLS 104 ... Charge storage device, 105 ... Voltage stabilization circuit, 106 ... Power supply switching device, 107 ... External power supply device, 150 ... Input capacitor, 151 ... Inductor, 152 ... Freewheel diode, 153 ... Output capacitor, 154 ... Switching transistor, 171 ... Digital photo frame, 171a ... Display unit, 175 ... Input connector, 176 ... Output connector, 177 ... Solar charging device, 178 ... Switch, 179 ... Comparator, 180 ... Power generation unit, 190 ... Bypass device, 200 ... Electronic circuit.

Claims (10)

A first circuit;
A second circuit;
Including
The first circuit includes:
Output voltage of solar cell,
Or output current,
Based on at least one of
Determine the operating point of the solar cell;
The first circuit controls the second circuit so that the solar cell operates at the operating point;
The circuit device characterized in that the second circuit outputs electric power from the solar cell. The circuit device according to claim 1,
The second circuit controls the operating point by pulse modulation control.
A circuit device. The circuit device according to claim 1, wherein:
A third circuit is provided between the second circuit and the power storage device;
The third circuit includes:
Limiting the charging current supplied to the power storage device within a rated range of the power storage device;
A circuit device. The circuit device according to any one of claims 1 to 3,
A fourth circuit at the output terminal of the second circuit;
The fourth circuit includes
Stabilizing the voltage output by the second circuit;
A circuit device. The circuit device according to any one of claims 1 to 4,
The second circuit includes an inductor having one end connected to the solar cell;
A transistor connected between the other end of the inductor and a portion having a first potential;
A diode having one end connected between the other end of the inductor and an output terminal of the second circuit;
Including
The circuit device, wherein the transistor is subjected to pulse modulation control by the first circuit. The circuit device according to claim 5,
The other end of the diode;
A first capacitor connected between the first potential region and the other end of the inductor;
At least one of the second capacitors connected to the portion having the first potential;
A circuit device further comprising: A first circuit;
A second circuit;
Including
The first circuit includes:
Based on the output voltage of the solar cell, or at least one of the output current,
Determine the operating point of the solar cell;
The first circuit controls the second circuit so that the solar cell operates at the operating point;
The circuit device, wherein the second circuit outputs electric power from the solar cell. The circuit device according to claim 7,
The second circuit includes an inductor having one end connected to the solar cell;
A transistor connected between the other end of the inductor and a portion having a first potential;
A diode having one end connected between the other end of the inductor and an output terminal of the second circuit;
Including
The circuit device, wherein the transistor is PWM-controlled by the first circuit. The circuit device according to claim 8, wherein
The other end of the diode;
A first capacitor connected between the first potential region and the other end of the inductor;
At least one of the second capacitors connected to the portion having the first potential;
A circuit device further comprising:   An electronic apparatus comprising the circuit device according to claim 1.

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