JP2005253166A - Power unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power unit which can drive excessive load with weak power being generated by the utilization of natural energy. <P>SOLUTION: This power unit is equipped with a capacitance SC which supplies a terminal T2 with power supplied from a power source 10, being connected to the output terminal T1 of the power source 10 including a power generating element GE for generating power, making use of natural energy such as s solar battery, etc., a power control circuit 12 which controls the discharge of the charge power, and a regulator 13 which outputs specified voltage, and this drives load 14 by the power charged in the capacitance. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a power supply device, and more particularly to a power supply device that supplies weak generated power to a load.

  As a conventional example of a power source using natural energy, a self-powered transmitter using a piezoelectric element as a power source of the transmitter is known (see, for example, Patent Document 1). In this method, the power generated by the piezoelectric element is charged into a capacitor, and the power is used to perform a transmission operation that requires relatively high power. The outline of the operation principle is as follows.

  By monitoring the charging voltage of the capacity, it is determined whether or not the power capable of transmitting a signal to the capacity has been secured, and when the power has been secured, the power is supplied to the transmitter via the discharge switch. Thereafter, the supply of power is continued until the end of the transmission, and when the transmission ends, the discharge switch is turned off to efficiently charge the power and the supply of power is stopped. By configuring a power supply that operates in this manner, it is possible to efficiently utilize the power generated by the piezoelectric element and transmit a signal that requires relatively high power.

JP 2003-133971 A

  The above-described conventional power supply device can drive a load that consumes relatively high power using the power generated by the piezoelectric element. However, in the configuration of this conventional example, the transmitter that is the load of the power supply is only allowed to perform a predetermined operation. This is because this power supply device determines whether or not the energy required by the load can be secured by determining whether or not the voltage of the capacitor has reached a predetermined voltage. Therefore, since the load cannot know the amount of energy present in the capacity at the present time, it can only repeat the determined operation after securing the energy necessary for the operation once, and performs a complicated process like a sensor network system. Cannot be used as a system power supply.

  In addition, if the power consumption increases due to malfunctions or environmental changes during the operation of the transmitter and the charging energy is insufficient, the operation of the transmitter stops suddenly and the reliability of the system is impaired. is there. Further, in this case, since the load does not output a signal for turning off the discharge switch, the discharge switch is fixed in an on state. Therefore, there is a problem that the capacity charging efficiency is deteriorated because useless power is consumed even when the energy is charged.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a highly reliable power supply device that can drive a large load with a weak power source by charging power to a storage capacity.

An example of representative means of the present invention is as follows. That is, the power supply device according to the present invention discharges the charging energy charged in the storage capacity based on the storage capacity for charging the supplied energy and the first and second predetermined voltages that are charging voltages of the storage capacity. And a power control circuit that controls the stop, and a regulator that outputs a predetermined constant voltage to a load using the charging energy discharged by the control of the power control circuit,
When the charging energy is equal to or higher than the first predetermined voltage, the charging energy can be discharged to drive the load, and the charging energy is smaller than the first predetermined voltage. When the voltage is equal to or lower than the voltage, discharging for driving the load of the charging energy is stopped.

  In this case, in the above power supply device, the energy supplied to the power storage capacity includes a power generation element that generates power using natural energy, and cathodes connected in series between the output of the power generation element and the ground potential. It is preferable that power is supplied from a power source having a protection circuit that prevents backflow to the power generating element including a diode and a Zener diode.

  ADVANTAGE OF THE INVENTION According to this invention, the power supply device which can drive a big load with the charge energy of the electrical storage capacity in which the weak electric power generated using natural energy is charged is realizable. In addition, a highly reliable power supply device can be realized even if the amount of power generation is unstable.

  Hereinafter, several preferred embodiments of a power supply device according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a block diagram showing a configuration of a first embodiment of a power supply apparatus according to the present invention. The power supply apparatus includes a power supply 10, a storage capacity SC, a power control circuit 12, and a regulator 13. , The load 14 is driven. Here, the power source 10 includes a power generation element (GE) 100 and a protection circuit 101. The power generation element 100 generates power using natural energy such as the sun, vibration, and temperature difference. By connecting the output terminal T1 of the power supply 10 and the terminal T2 of the power control circuit, the electrical energy generated by the power supply 10 is stored in the storage capacitor SC. In the following description, it is assumed that the output terminal T1 of the power supply 10 and the terminal T2 of the power control circuit 12 are connected.

  FIG. 8 and FIG. 9 show the respective power generation amounts PWR when using solar cells and vibrations as power generation elements. The dimensions of the solar cell and the power generation element using vibration are 53 mm × 50 mm and 50 mm × 30 mm, respectively. FIG. 8 shows the illuminance IL [Lx] dependency of the power generation amount PWR [μW] of the solar cell, and FIG. 9 shows the dependency of the power generation amount PWR [μW] of the power generation element using vibration on the vibration amplitude value AM [μm]. It is a figure. As can be seen from FIGS. 8 and 9, the power generation amount of the power generation element using such natural energy is as weak as about several hundred μW, and varies depending on the power generation environment.

  For example, the amount of power generation varies depending on the illuminance IL in the case of a solar cell and the amplitude value AM in the case of vibration.

  The protection circuit 101 includes a diode D and a Zener diode ZD. Since the output of the power generation element 100 is output to the outside from the output terminal T1 as the output voltage VDC of the power supply 10 via the diode D, it is possible to prevent a reverse current flow from the outside. Further, the Zener diode of the protection circuit 101 is disposed between the output voltage VDC and the ground to prevent the voltage VDC from exceeding the Zener voltage VLT.

  The storage capacity SC is a capacity for storing power supplied from the power supply 10 as power for operating the load 14. When power is supplied from the power supply 10 to the storage capacity SC, the output voltage VDC, that is, the charging voltage VDC increases, and when the charging energy is discharged to the load 14, the charging voltage VDC decreases. Depending on the power consumed by the load 14 and the voltage of the charging voltage VDC, it is desirable that the storage capacity SC has a relatively high capacity and a low equivalent resistance.

  The power control circuit 12 includes a voltage monitoring circuit DET1 that monitors the first predetermined voltage VH, a voltage monitoring circuit DET2 that monitors a second predetermined voltage VL lower than the first predetermined voltage, a power switch SW1, and a voltage monitor The switch control circuit 120 includes two NAND gates N1 and N2 to which the output VDEC of the circuits DET1 and DET2 is input.

  Here, the second predetermined voltage VL is set to be equal to or higher than the minimum voltage value required to drive the load 14. The power control circuit 12 is a circuit that controls the discharge of the charging energy charged in the storage capacity SC. The power switch SW1 inserted between the storage capacitor SC and the regulator 13 is not particularly limited as long as it is a switch, but a PMOSFET is used in this embodiment. This PMOS switch is turned on when the control signal VCL of the switch control circuit 120 applied to the gate is low (“L”) and turned off when it is high (“H”).

  The charging voltage VDC of the storage capacitor SC is monitored by the voltage monitoring circuit DET1 and the voltage monitoring circuit DET2, and when the charging voltage VDC is charged to be equal to or higher than the first predetermined voltage VH, the switch control circuit 120 sets the control signal VCL to “L”. Controlling to the level, the charging energy charged in the storage capacity SC is discharged. Thereafter, the discharging is continued until the charging voltage VDC decreases to the second predetermined voltage VL. When the charging voltage VDC becomes equal to or lower than VL, the switch control circuit 120 controls the control signal VCL to the “H” level to store the storage capacity. Stop the SC discharge.

  FIG. 10 shows an example of the configuration of the voltage monitoring circuits DET1 and DET2. The voltage monitoring circuits DET1 and DET2 have the same circuit configuration, and only the values of resistors R3 and R4 for setting the voltage values VH and VL to be detected are different. Therefore, the voltage monitoring circuit DET1 will be described. The voltage monitoring circuit DET1 includes two comparison circuits CMP1 and CMP2 that compare the reference voltage VREF and the voltage of the connection node n34 of the resistors R3 and R4, that is, the voltage obtained by dividing the charging voltage VDC by the resistors R3 and R4, and the amplitude of the detection signal. Is converted to a charging voltage VDC level, and a buffer circuit BUF composed of a CMOS inverter for preventing the voltage monitoring circuit from being affected by the load.

  The voltage monitoring circuit DET1 configured as described above determines whether or not the charging voltage VDC is equal to or higher than (R3 + R4) VREF / R4. Therefore, in order to detect the first predetermined voltage VH, the ratio of the resistors R3 and R4 is set so that the voltage at the node n34 becomes the same voltage as the reference voltage VREF when the voltage value of the charging voltage VDC becomes VH. You only have to set it.

  Similarly, in the case of the voltage monitoring circuit DET2, the ratio of the resistors R3 and R4 may be set so as to detect the second predetermined voltage VL.

  FIG. 11 is a circuit diagram showing an example of a reference voltage generating circuit that generates the reference voltage VREF. This is a known bandgap reference circuit composed of a current source I1, three NPN transistors Q1 to Q3, and three resistors R5 to R7, and is inserted between the charging voltage VDC and the ground so as to have a constant voltage VREF. Is output. The reference voltage generation circuit may be provided in the vicinity of each circuit, or when a voltage drop can be ignored due to wiring resistance, the reference voltage VREF may be supplied from one reference voltage generation circuit to each circuit. .

  The regulator 13 is a series regulator composed of a non-inverting amplifier circuit having a reference voltage VREF as one input and a negative feedback connection with the voltage at the connection node n12 of the resistors R1 and R2 as the other input. The non-inverting amplifier circuit amplifies the reference voltage VREF by (R1 + R2) / R2 times. Therefore, the regulator 13 outputs (R1 + R2) VREF / R2 as the output voltage VREG.

  The load 14 is a load that consumes power charged in the storage capacity SC. In the present embodiment, a sensor network terminal having functions of wireless (RAD), microprocessor (MPRO), and sensor (SENS) in the sensor network system as shown in FIG. 7 is assumed, but the present invention is particularly limited to this. Not what you want. FIG. 7 is a configuration diagram of the sensor network system. In the sensor network system, countless autonomous operation terminals (SENSTM) detect information and communicate with the base station (BST), so that the information is directly connected to the network (NTWK) and processing is performed. is there. Since sensor network terminals are installed everywhere, securing power is a problem. Therefore, although it is weak, power sources using natural energy have been actively developed.

  The sensor network terminal 14 which is a load in this embodiment senses information, processes it with a microprocessor, and communicates information with a base station (BST). The sensor network terminal 14 has a plurality of operation modes (OP_MOD).

  FIG. 12 shows the operation mode and power consumption PWR_C of the sensor network terminal 14. The power consumption varies greatly depending on the operation mode, and in some operation modes such as communication (TX) mode, signal processing (SG), sensing (SEN) mode, much more power than the power generated by the power supply 10 is consumed. To do.

  However, most of the time is operating in low-power modes such as timer operation (TM) mode and shut-off (SHT) mode, and it operates in a mode that consumes a large amount of power such as signal processing and communication for a very short time. . As described above, the sensor network terminal 14 has a plurality of operation modes, and power consumption varies greatly depending on the operation mode, and the sensor network terminal 14 operates in a mode in which large power is intermittently consumed.

Next, the operation of this embodiment will be described.
FIG. 2 shows operation waveforms of the charging voltage VDC of the storage capacitor SC, the control signal VCL that is the output of the switch control circuit 120, and the output voltage VREG of the regulator 13 in this embodiment. In FIG. 2, the horizontal axis represents time, ST represents the case where the power generation amount PWR by the power generation element 100 is strong, and WK represents the case where the power generation amount PWR is weak. PSS indicates a period in which power is supplied from the power supply source. In this case, PSS indicates a period in which charging energy is supplied from the storage capacity SC.

  At time A, power generation by the power source 10 is started. Here, the power generation amount PWR is in a strong (ST) state. The charging voltage VDC increases as the storage capacity SC is charged. Until the charging voltage VDC reaches the first predetermined voltage VH, the control signal VCL for controlling the power switch SW1 in the power control circuit 12 is “H”, the power switch SW1 is in an off state, and power is supplied to the load 14. Since PWR is cut off and not supplied, the operation mode OP_MOD is a cut-off mode SHT.

  When the charging voltage VDC reaches the first predetermined voltage VH at time B, the control signal VCL becomes “L”, the power switch SW1 is turned on, the energy charged in the storage capacitor SC is discharged, and the regulator 13 is predetermined. The constant voltage VREG is output to the load. When power is supplied, the sensor network terminal 14 starts an intermittent operation that operates in a mode in which power consumption is large for a short time. After the operation starts, power is consumed according to the operation mode, and the charging voltage VDC decreases accordingly. In the example of FIG. 2, signal processing SG is performed between times BC and communication TX is performed between times CD, and the charging voltage VDC decreases according to the power consumption of the load 14.

  After time D, the load 14 enters the timer operation TM. Since the timer operation consumes less power, the charging voltage VDC recovers but does not rise above the Zener voltage VLT by the protection circuit 101.

  After time G, the power generation amount PWR of the power supply 10 is reduced and weak (WK) due to a change in the power generation environment. Therefore, the charging voltage VDC gradually decreases as the load 14 continues the intermittent operation of the signal processing mode SG and the communication mode TX.

  At time P, the voltage finally drops to the second predetermined voltage VL. When the charging voltage VDC becomes equal to or lower than VL, the control signal VCL again outputs “H”, turns off the power switch SW1, and stops discharging the energy charged in the storage capacitor SC. Once the power switch SW1 is turned off, the off state is continued until the time Q at which the charging voltage VDC is charged to the first predetermined voltage VH or higher again, and the power generated by the power source 10 is charged only for charging.

  In this way, the power generated by the power source 10 using natural energy is charged into the storage capacitor SC, and the charging voltage is monitored with two voltages, the first predetermined voltage VH and the second predetermined voltage VL, and the load of the storage capacitor SC is loaded. By controlling the discharge to 14 with hysteresis, the operating energy of the load circuit can be efficiently and sufficiently secured. Therefore, it is possible to realize a power supply device that can drive a load with excessive power consumption using a weak power supply.

  In this embodiment, for example, when a solar cell is used as the power generation element and a capacity of about 22 mF is used as the storage capacity, the voltage of the storage capacity is controlled to about 3.5 to 5 V, and a voltage of about 3 V is used as the output of the regulator. Therefore, it is possible to provide a power supply device suitable for a sensor network terminal of a sensor network system that performs intermittent operation that consumes several tens of mW of power for a period of 100 ms every 5 minutes.

  In FIG. 2, the sensing operation, which is an operation mode with high power consumption, is omitted, but the case where the continuous operation with the sensing mode, the signal processing mode, and the transmission mode as a set is intermittently performed is also described. Since the power consumption increases in this case, if the intermittent operation interval is the same, the time at which the charging voltage VDC becomes equal to or lower than the second predetermined voltage VL is earlier.

  FIG. 3 is a block diagram showing the configuration of the second embodiment of the power supply apparatus according to the present invention. In FIG. 3, the power supply and the power control circuit are illustrated as being directly connected without terminals, but it is needless to say that the terminals may be connected as shown in FIG. The same applies to a third embodiment of FIG. 5 described later.

  Here, portions corresponding to those in FIG. 1 are denoted by the same reference numerals, and redundant description thereof is omitted. That is, the power supply apparatus in the present embodiment has the same configuration as that of the first embodiment except for the power control circuit 32 and the load 34 that control the discharge of energy charged in the storage capacitor SC.

  The detection voltage VL ′ of the voltage monitoring circuit DET2 that monitors the second predetermined voltage that constitutes the power control circuit 32 is a voltage that is higher than the minimum voltage VL required to drive the load 34.

  Unlike the switch control circuit 120 of the first embodiment, the switch control circuit 320 includes a NAND gate N3 and a delay circuit D. The switch control circuit 320 controls the power switch SW1 by the output of the NAND gate N3, and the output of the NAND gate N1 is stored power. As a VCHG signal indicating this state, the signal is transmitted to the microprocessor MPRO of the load 34 which is a sensor network terminal.

  The VCHG signal indicates a state where charging energy is secured at “H”, and indicates a state where charging energy is reduced or exhausted at “L”. The power control circuit 32 monitors the charging voltage VDC of the storage capacitor SC with the voltage monitoring circuits DET1 and DET2, and when the charging voltage VDC is charged to the first predetermined voltage VH or higher, the switch control circuit 320 outputs the VCHG signal “ It is changed from “L” to “H” to output to the load 34 that sufficient charge energy is secured in the storage capacity SC.

  Further, by changing the control signal VCL from “H” to “L”, the power switch SW1 is turned on to discharge the charging energy stored in the storage capacitor SC. The discharge continues, and when the charging voltage VDC decreases to the second predetermined voltage VL ′, the VCHG signal is controlled to “L”, and a warning signal indicating that the stored power has decreased is sent to the load 34. Then, after the time set by the delay circuit D in the switch control circuit 320, the control signal VCL is controlled to "H" to stop discharging the charging energy of the storage capacitor SC. The delay time of the delay circuit D is set to a time longer than the time required for the termination process performed by the load 34 after the warning signal is transmitted.

  The load 34 is obtained by adding a VCHG signal as an input to a load having the same configuration as that of the first embodiment. When the VCHG signal is “H”, the load 34 is supplied with charging energy of the storage capacity SC, and intermittently performs operations such as communication and signal processing. When the energy charged in the storage capacitor SC decreases and the VCHG signal of “L” level is input, the load 34 changes the operation mode and performs a predetermined operation as an end operation. It is also possible to increase the stability of the network system by transmitting a stop signal to the base station. When these operations are finished, it waits for the power to be cut off.

  As the delay circuit D, for example, a delay circuit having a configuration in which inverters are connected in cascade can be used. However, the delay circuit is not limited to this, and a delay circuit having another configuration may be used.

Next, the operation of this embodiment will be described.
FIG. 4 shows operation waveforms of the charging voltage VDC of the storage capacitor SC, the VCHG signal and control signal VCL of the switch control circuit 320, and the output voltage VREG of the regulator 13 of this embodiment. In FIG. 4, the horizontal axis represents time, ST represents a case where the power generation amount PWR by the power generation element 100 is strong, and WK represents a case where the power generation amount is weak. PSS indicates a period in which power is supplied from the power supply source. In this case, PSS indicates a period in which charging energy is supplied from the storage capacity SC.

  At time A, power generation of the power source 10 is started, and the power generation amount PWR is in a strong (ST) state. The charging voltage VDC increases as the storage capacity SC is charged. Until the charging voltage VDC reaches the first predetermined voltage VH, the control signal VCL for controlling the power switch SW1 in the power control circuit 32 is “H”, and the power switch SW1 is in an off state and is supplied to the load 34. Since the power PWR is cut off and not supplied, the operation mode OP_MOD is the cut-off mode SHT. Further, the VCHG signal indicating the charging energy information outputs “L”.

  When the charging voltage VDC reaches VH at time B, the control signal VCL becomes “L”, the power switch SW1 is turned on, the energy charged in the storage capacitor SC is discharged, and power is supplied. A predetermined voltage VREG is output to the load 34. At the same time, the VCHG signal becomes “H” and transmits to the load 34 that the charging energy of the storage capacity SC is sufficiently secured. When power is supplied and the VCHG signal becomes “H”, the sensor network terminal 34 as a load starts an intermittent operation that operates in a mode in which power consumption is large for only a short time. After the operation starts, power is consumed according to the operation mode, and the charging voltage VDC decreases accordingly. In the example of FIG. 4, the signal processing mode SG is operated between the times B and C, and the communication mode TX is operated between the times C and D, and the charging voltage VDC decreases according to the power consumption of the load 34.

  After time D, the sensor network terminal 34 enters the timer operation TM. Since the timer operation consumes little power, the charging voltage VDC recovers but does not rise above the Zener voltage VLT by the protection circuit 101.

  After time G, the power generation amount PWR of the power supply 10 is reduced and weak (WK) due to a change in the power generation environment. Therefore, as the sensor network terminal continues intermittent operation, the charging voltage VDC gradually decreases, and at time M, finally decreases to the second predetermined voltage VL ′. When the charging voltage VDC decreases to the second predetermined voltage VL ′, the switch control circuit 320 sets the VCHG signal to “L” and warns the sensor network terminal 34 that the charging energy has decreased. Upon receiving this VCHG signal, the sensor network terminal performs a preset end operation EN between times MN.

  After the VCHG signal changes from “H” to “L”, after a predetermined time created by the delay circuit D of the switch control circuit 320, the control signal VCL becomes “H”, the power switch 320 is turned off, and the storage capacity SC Is stopped, and the operation mode becomes the cutoff mode SHT.

  Here, the delay time of the delay circuit is determined from the time required for the termination process of the sensor network terminal 34, the storage capacity SC, and the second predetermined voltage VL '. Once the power switch 320 is turned off, the power supply 10 continues to be turned off until the charging voltage VDC is charged again to the first predetermined voltage VH or higher until the time O, and the power generated by the power supply 10 is charged to the storage capacitor SC. Dedicated to

  In this way, the power supplied from the power source 10 generated using natural energy is charged to the capacity, and the charge voltage is monitored with the two voltages, the first and second predetermined voltages VH and VL ′, and the load to the capacity is loaded. By controlling the discharge with hysteresis, the operating energy of the load circuit can be secured efficiently and sufficiently.

  Furthermore, in this embodiment, by providing a signal that warns that the charging energy has decreased, the operation mode can be changed before the charging energy is exhausted, and a predetermined operation can be performed as the end operation. .

  Moreover, since the load circuit which is a sensor network terminal can also transmit a stop signal to the base station, a stable network system can be realized. Therefore, a power supply device that can drive a load with excessive power consumption using a weak power supply can be realized, and the reliability of the power supply device when the power generation amount of the power supply is unstable can be improved.

  FIG. 5 is a block diagram showing the configuration of the third embodiment of the power supply apparatus according to the present invention. The power supply apparatus according to the present embodiment has the same configuration as that of the first embodiment except for the power control circuit 52.

  Here, portions corresponding to those in FIG. 1 are denoted by the same reference numerals, and redundant description thereof is omitted. That is, a second power switch SW2 and an auxiliary power supply VBAT are newly added in the power control circuit 52, and two switch control signals VCL and VCLB are output from the switch control circuit 520.

  The power control circuit 52 controls the discharge of energy charged in the storage capacity SC. The first power switch SW1 and the second power switch SW2 are not particularly limited as long as they are switches. However, the first power switch SW1 and the second power switch SW2 are realized by using PMOSFETs and are turned on when the gate voltage is “L”. Turns off when "". The switch control circuit 520 outputs a control signal VCL for controlling the power switch SW1 and a VCLB signal for controlling the power switch SW2. The VCLB signal is an inverted signal of the control signal VCL. Accordingly, only one of the power switches SW1 and SW2 is always on.

  The power control circuit 52 monitors the charging voltage VDC of the storage capacitor SC with the voltage monitoring circuits DET1 and DET2, and when the charging power VDC is charged to the first predetermined voltage VH or higher, the switch control circuit 520 outputs the control signal VCL. By changing from “H” to “L”, the charging energy charged in the storage capacitor SC is discharged.

  Thereafter, discharging is continued until the charging voltage VDC decreases to the second predetermined voltage VL. When the charging voltage VDC falls below VL, the switch control circuit 520 controls the control signal VCL from “L” to “H”. Then, the discharging of the storage capacity SC is stopped. Since the power supply from the auxiliary power supply VBAT is controlled using the VCLB signal which is an inverted signal of the control signal VCL, when the discharge from the storage capacitor SC is interrupted by the power switch SW1, the power supply to the regulator 13 is supplied. Electric power is supplied from the auxiliary power supply VBAT by the switch SW2.

Next, the operation of this embodiment will be described.
FIG. 6 shows operation waveforms of the charging voltage VDC, the control signal VCL, and the regulator output voltage VREG of this embodiment. In FIG. 6, the horizontal axis represents time, ST represents a case where the power generation amount PWR by the power generation element 100 is strong, and WK represents a case where the power generation amount is weak. PSS indicates a period during which power is supplied from the power supply source. In this case, PSS indicates a period during which energy is supplied from the storage capacitor SC and the auxiliary power supply VBAT.
In this embodiment, since power is always supplied to the load 14, an intermittent operation characterized by operating in a mode in which power consumption is large for only a short time is always performed.

At time A, power generation is started, and the power generation amount PWR is in a strong (ST) state. The charging voltage VDC increases as the storage capacity SC is charged.
Until the charging voltage VDC reaches the first predetermined voltage VH at time B, the signal VCL for controlling the power switch SW1 in the power control circuit 52 is "H", and the signal VCLB for controlling the power switch SW2 is "L". The power switch SW1 is off and SW2 is on. Therefore, until time B, power is supplied from the auxiliary power supply VBAT to the load 14 through the regulator 13, and the power supplied from the power supply 10 is charged in the storage capacitor SC. When the charging voltage VDC reaches the first predetermined voltage VH at time B, the control signal VCL becomes “L”, the VCLB signal becomes “H”, the power switch SW2 is turned off and the power supply from the auxiliary power supply VBAT is stopped simultaneously. When the power switch SW1 is turned on, the charging energy charged in the storage capacitor SC is discharged, and power is supplied to the load 14 through the regulator 13. The sensor network terminal of the load 14 consumes power corresponding to the operation mode. During the period in which the power of the storage capacity SC is supplied to the load 14, the charging voltage VDC decreases according to the power consumption. In the example of FIG. 6, signal processing SG is performed between times B and C, communication TX is performed between C and D, and the charging voltage VDC decreases according to the power consumption of the load 14.

  After time D, the sensor network terminal enters the timer operation TM. Since the timer operation consumes little power, the charging voltage VDC recovers but does not rise above the Zener voltage VLT by the protection circuit 101.

  After time G, the power generation amount PWR of the power source 10 decreases due to a change in the power generation environment, and is weak (WK). Therefore, the charging voltage VDC gradually decreases as the sensor network terminal continues intermittent operation.

  At time P, the voltage finally drops to the second predetermined voltage VL. When the charging voltage VDC becomes equal to or lower than VL, the control signal VCL again outputs “H”, turns off the power switch SW1, and stops discharging the storage capacitor SC. At the same time, the VCLB signal outputs “L”, turns on the power switch SW2, and supplies power from the auxiliary power supply VBAT to the load 14. Once the charging voltage VDC becomes VL or lower, the auxiliary power source VBAT supplies power for driving the load until the charging voltage VDC is charged again to VH or higher again, and the power generated by the power source 10 is stored in the storage capacity. It is used only for charging the SC.

  In this way, the power generated using natural energy is charged into the capacity, the charging voltage is monitored with two voltages VL and VH, and the discharge from the storage capacity to the load is controlled by hysteresis, thereby reducing the operating energy of the load circuit. It can be secured efficiently and sufficiently. Furthermore, when the charged power is reduced and the load cannot be driven, power is supplied from the connected auxiliary power supply, so that the load circuit can always be operated. Therefore, a power supply device that can drive a load with excessive power consumption using a weak power source can be realized. Further, even when the power generation amount of the power source is unstable, it is possible to always supply power to the load. Since the power supply to the load does not stop due to the provision of the auxiliary power supply, the present embodiment can be applied to an application in which information needs to be constantly maintained.

The block diagram which shows the structure of the 1st Example of the power supply device which concerns on this invention. The wave form diagram which shows the circuit operation | movement of the power supply device of a 1st Example. The block diagram which shows the structure of the 2nd Example of the power supply device which concerns on this invention. The wave form diagram which shows the circuit operation | movement of the power supply device of a 2nd Example. The block diagram which shows the structure of the 3rd Example of the power supply device which concerns on this invention. The wave form diagram which shows the circuit operation | movement of the power supply device of a 3rd Example. The block diagram of a sensor network system. The figure which shows the illumination intensity dependence of the electric power generation amount at the time of utilizing a solar cell. The figure which shows the vibration amplitude dependence of the electric power generation amount at the time of utilizing vibration energy. The circuit diagram which shows an example of a structure of the voltage monitoring circuit of the power supply device which concerns on this invention. The circuit diagram which shows an example of the reference voltage generation circuit used with the power supply device which concerns on this invention. The figure which shows the power consumption of each operation mode of a sensor network terminal.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Power supply, 12, 32, 52 ... Power control circuit, 14 ... Load, 100 ... Power generation element (GE), 101 ... Protection circuit, 120, 320, 520 ... Switch control circuit, AM ... Vibration amplitude value, BST ... Base Station, BUF ... buffer, D ... diode, DET1, DET2 ... voltage monitoring circuit, I1 ... current source, IL ... illuminance, LVC ... level conversion circuit, MPRO ... microprocessor, MNGSV ... management server, n12, n34 ... node, N1 N3 ... NAND gate, NTWK ... network, OP_MOD ... operation mode, PSS ... power supply source, PWR ... power generation amount, PWR_C ... power consumption, Q1-Q3 ... NPN transistor, R1-R7 ... resistor, RAD ... wireless, SC ... Storage capacity, SEN ... Sensing, SENS ... Sensor, SENSTM ... Sensor network terminal, SG ... Processing, SW1, SW2 ... Power switch, T1, T2 ... Terminal, TX ... Communication, VBAT ... Auxiliary power supply, VCLB ... Inversion control signal, VCL ... Control signal, VREF ... Reference voltage, VDC ... Charging voltage, VDEC ... Voltage monitoring circuit Output, VREG ... Regulator output, ZD ... Zener diode.

Claims (8)

A storage capacity for charging the supplied energy;
A power control circuit for controlling discharge and stop of charging energy charged in the storage capacity based on first and second predetermined voltages that are charging voltages of the storage capacity;
A regulator that outputs a predetermined voltage to a load using the charging energy discharged by the control of the power control circuit;
When the charging energy is equal to or higher than the first predetermined voltage, the charging energy can be discharged to drive the load, and the charging energy is smaller than the first predetermined voltage. When the voltage is equal to or lower than the voltage, discharging for driving the load of the charging energy is stopped. The power supply device according to claim 1,
The energy supplied to the storage capacity is
A power generation element that generates power using natural energy;
It is supplied from a power source having a protection circuit for preventing backflow to the power generation element, which includes a diode having a cathode connected in series between the output of the power generation element and a ground potential, and a Zener diode. Power supply. The power supply device according to claim 1,
The power control circuit includes:
A first power switch provided between the storage capacity and the regulator;
A first voltage monitoring circuit for detecting the first predetermined voltage;
A second voltage monitoring circuit for detecting a second predetermined voltage lower than the first predetermined voltage before;
A switch control circuit for controlling the first power switch based on the outputs of the first and second voltage monitoring circuits;
The switch control circuit turns on the first power switch based on the detection signal of the first voltage monitoring circuit to start discharging the charging energy, and the first control switch starts the discharging of the charging energy, based on the detection signal of the second voltage monitoring circuit. 1. The power supply apparatus according to claim 1, wherein the first power switch is controlled to turn off one power switch to stop discharging the charging energy. The power supply device according to claim 3,
The switch control circuit includes:
Means for transmitting to the load a warning signal indicating that the charge energy has decreased based on the second predetermined voltage detection signal of the second voltage monitoring circuit; and turning off the first power switch after a predetermined time. And a power supply apparatus. The power supply device according to claim 1,
The power control circuit includes:
An auxiliary power source, and a second power switch provided between the auxiliary power source and the regulator,
The switch control circuit includes:
Based on the detection signal of the first voltage monitoring circuit, the second power switch is turned off and the first power switch is turned on to discharge the charging energy, and then based on the detection signal of the second monitoring circuit The first power switch is turned off to stop discharging, and the second power switch is turned on to control the first and second power switches to supply energy from the auxiliary power to the regulator. Power supply. The power supply device according to claim 1,
The load includes a sensor for detecting predetermined data, a microprocessor for processing a signal, and a wireless circuit for transmitting and receiving the data, and has a plurality of operation modes with greatly different power consumption, and most of the time is little. A power supply apparatus that operates in a low-power mode that consumes only a small amount of power and operates in a high-power mode that consumes a large amount of power intermittently for a short period of time. The power supply device according to claim 4,
The load includes a sensor for detecting predetermined data, a microprocessor for processing a signal, and a wireless circuit for transmitting and receiving the data, and has a plurality of operation modes with greatly different power consumption, and most of the time is little. A load that operates in a low power mode that consumes only a small amount of power and operates in a large power mode that consumes a large amount of power intermittently for a short period of time,
When the warning signal output from the switch control circuit is input, an operation mode during operation of the load is changed to perform a predetermined process. The power supply device according to claim 7,
The power supply apparatus according to claim 1, wherein when the warning signal output from the switch control circuit is input, the load transmits a stop signal to a base station.

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