Power supply circuit and vibration power generation device

Abstract

A power supply circuit that outputs power input from a vibration power generating element to an external load, comprising: a negative half-wave rectifier circuit that half-wave rectifies the AC power input from the vibration power generating element into a negative voltage output; and an inverting chopper circuit that inverts the negative voltage output from the negative half-wave rectifier circuit into a positive voltage output and then outputs it.

Description

Technical Field

[0001] The invention relates to a power supply circuit and a vibration power generation device. Background Art

[0002] As one of the energy acquisition technologies for obtaining energy from environmental vibrations, a method of generating electricity from environmental vibrations using a vibration power generation element that is a MEMS (Microelectromechanical Systems) vibration element is known. The vibration power generation element itself has a piezoelectric element and an electrostatic capacitance type element. When the vibration power generation element is vibrated at the frequency of the environmental vibration, an AC power equal to the frequency is generated. Therefore, a vibration power generation device is proposed, which combines a vibration power generation element and a power supply circuit, and the power supply circuit converts the AC power generated by the vibration power generation element into a DC or AC voltage suitable for use (for example, refer to Patent Document 1). In Patent Document 1, in the rectification (conversion from AC to DC) of the AC power generated by the electrostatic capacitance type vibration power generation element, a common two-phase full-wave rectifier circuit is used as a rectifier circuit.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent No. 5990352 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] The vibration energy of environmental vibration is weak, and therefore a power supply circuit and a vibration power generation device that can efficiently convert environmental vibration into electrical energy are required.

[0008] Means used to solve problems

[0009] The power supply circuit of the first mode outputs the power input from the vibration power generating element to an external load, and comprises: a negative half-wave rectifier circuit, which half-wave rectifies the AC power input from the above-mentioned vibration power generating element into a negative voltage output; and an inverting chopper circuit, which inverts the above-mentioned negative voltage output output from the above-mentioned negative half-wave rectifier circuit into a positive voltage output and outputs it.

[0010] Preferably, the power supply circuit of the second aspect is the power supply circuit of the first aspect, further comprising a voltage conversion circuit that converts the positive voltage output from the inversion chopper circuit and outputs the converted voltage to the external load.

[0011] Preferably, the third-type power supply circuit further comprises a first capacitor in the power supply circuit of the first or second type, one end of the first capacitor being connected to the output portion of the above-mentioned negative half-wave rectifier circuit and the other end being grounded, accumulating the above-mentioned negative voltage output from the above-mentioned negative half-wave rectifier circuit and outputting it to the above-mentioned inversion chopper circuit.

[0012] Preferably, the power supply circuit of the fourth aspect further comprises a second capacitor in the power supply circuit of the third aspect, one end of the second capacitor being connected to the output portion of the negative half-wave rectifier circuit and the other end being grounded, for accumulating the positive voltage output from the inversion chopper circuit.

[0013] Preferably, the power supply circuit of the fifth mode further comprises a control circuit in the power supply circuit of the third or fourth mode, wherein when the voltage at the above-mentioned one end of the above-mentioned first capacitor becomes a first reference negative voltage, the above-mentioned control circuit will turn on the switch element for controlling the chopping timing in the above-mentioned reversing chopper circuit, and when the voltage at the above-mentioned one end of the above-mentioned first capacitor becomes a second reference negative voltage closer to the positive side than the first reference negative voltage, the above-mentioned control circuit will turn off the switch element for controlling the chopping timing in the above-mentioned reversing chopper circuit.

[0014] The power supply circuit of the sixth embodiment is preferably the power supply circuit of the fifth embodiment, wherein the control circuit comprises: a Zener diode, arranged between the one end and the other end of the first capacitor with its anode facing the one end of the first capacitor; a resistor element, arranged between the first capacitor and the Zener diode; and a voltage divider, arranged between the one end and the other end of the first capacitor, for dividing the voltage at the one end of the first capacitor and the voltage at the other end of the first capacitor, and the control circuit turns on and off the switching element according to a comparison result between the voltage applied at both ends of the Zener diode and the output voltage of the voltage divider.

[0015] Preferably, in the power supply circuit of the seventh aspect, in the power supply circuit of the sixth aspect, one end of the above-mentioned resistance element is connected to the above-mentioned one end of the above-mentioned first capacitor, the other end is connected to the above-mentioned anode of the above-mentioned Zener diode, and the cathode of the above-mentioned Zener diode is connected to the above-mentioned other end of the above-mentioned first capacitor.

[0016] The power supply circuit of the eighth embodiment is preferably the power supply circuit of the sixth or seventh embodiment, wherein the control circuit includes a comparison circuit, an input side feedback resistor, and an output side feedback resistor, the voltage of the anode of the Zener diode is input to a first input of the comparison circuit, the output voltage of the voltage divider is input to a second input of the comparison circuit via the input side feedback resistor, and the output of the comparison circuit is input via the output side feedback resistor, and the control circuit turns on and off the switching element according to the output of the comparison circuit.

[0017] A vibration power generating device according to a ninth aspect includes: the power supply circuit according to any one of the first to eighth aspects; and a vibration power generating element that supplies electric power to the power supply circuit.

[0018] Preferably, the vibration power generating device of the tenth embodiment is a vibration power generating device of the ninth embodiment, wherein the electrode of the vibration power generating element forming an electret with negative charge is connected to the input part of the negative half-wave rectifier circuit of the power supply circuit, and the electrode without an electret is connected to the ground in the power supply circuit, or the electrode of the vibration power generating element without an electret is connected to the input part of the negative half-wave rectifier circuit of the power supply circuit, and the electrode forming an electret with positive charge is connected to the ground of the power supply circuit.

[0019] Effects of the Invention

[0020] According to the present invention, the energy of environmental vibration can be efficiently converted into electrical energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram showing the schematic configuration of the power supply circuit 50 and the vibration power generating device 100 according to the first embodiment of the present invention.

[0022] Figure 2 This is a diagram for explaining the outline of the vibration power generating element 10 included in the vibration power generating device 100 .

[0023] Figure 3 This is a diagram for explaining the operating principle of the vibration power generating element 10 .

[0024] Figure 4 The power generation output when the negative half-wave rectification circuit 20 is used is compared with the power generation output when the full-wave rectification circuit is used.

[0025] Figure 5 A diagram showing time changes in the voltage VP1 of the input portion P1 of the inversion chopper circuit 30 .

[0026] Figure 6 It is a schematic diagram showing the schematic configuration of a power supply circuit 50a and a vibration power generating device 100a according to the second embodiment of the present invention.

[0027] Figure 7 This is a diagram for explaining the outline of the vibration power generating element 10 a included in the vibration power generating device 100 a . DETAILED DESCRIPTION

[0028] (First Embodiment)

[0029] Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. Figure 11 is a schematic diagram showing the schematic configuration of a power supply circuit 50 and a vibration power generating device 100 according to the first embodiment of the present invention. The vibration power generating device 100 includes a vibration power generating element 10 that generates AC power by environmental vibration, and a power supply circuit 50 that obtains the generated AC power as a power source.

[0030] The power supply circuit 50 includes a negative half-wave rectifier circuit 20 that outputs only the negative voltage component of the power input from the vibration power generating element 10, and an inversion chopper circuit 30 that converts the negative voltage power from the negative half-wave rectifier circuit 20 into a positive voltage. The power supply circuit 50 may further include a voltage conversion circuit 40 that converts the positive voltage power from the inversion chopper circuit 30 into a predetermined positive voltage power.

[0031] As an example, the vibration power generating element 10 is an electrostatic capacitance type power generating element (electret type power generating element) having an electret electrode. Figure 2 Describe its outline.

[0032] The vibration power generating element 10 includes a first electrode 11 as a movable electrode and a second electrode 12 as a fixed electrode. The first electrode 11 is a comb-tooth electrode including two comb-tooth portions 15 as an example, and the second electrode 12 is a comb-tooth electrode including three comb-tooth portions 16 as an example.

[0033] The comb teeth 15 of the first electrode 11 and the comb teeth 16 of the second electrode 12 have a predetermined thickness in the Z direction of the figure, and face each other at their interlocking portions. For example, the first electrode 11 and the second electrode 12 can be manufactured as a MEMS structure using silicon as a base material.

[0034] A surface region 17 of the comb-teeth portion 16 of the second electrode 12 facing the comb-teeth portion 15 of the first electrode 11 is subjected to a known charging process (for example, the charging process described in Japanese Patent Application Laid-Open No. 2014-049557) to form an electret having negative charge.

[0035] The formation of the electret semi-permanently charges the comb-teeth 16 of the second electrode 12. As a result, positive induced charges are induced in the comb-teeth 15 of the first electrode 11 facing the electrode forming the electret, which are opposite to the characteristics of the electrode forming the electret.

[0036] The second electrode 12 is fixedly held by an insulating support frame 13 .

[0037] On the other hand, the first electrode 11 is held by the holding portion 14 (electrode holding portion 14a, connecting portion 14b, fixing portion 14c) so as to vibrate in the vertical direction (X direction) in the figure relative to the support frame 13. The holding portion 14 is composed of the electrode holding portion 14a that holds the first electrode 11, the fixing portion 14c that is fixed to the support frame 13, and the connecting portion 14b that has flexibility and connects the electrode holding portion 14a and the fixing portion 14c.

[0038] The connecting portion 14b is Figure 1 The thickness in the X direction is thin and the thickness in the Z direction is thick, which is made of a flexible material such as metal. When vibration is applied to the support frame 13 from the outside, the two connecting parts 14b provided on the left and right of the electrode holding part 14a in the figure are bent, so that the electrode holding part 14a vibrates in the X direction relative to the support frame 13. As a result, the first electrode 11 held by the electrode holding part 14a is configured to vibrate in the X direction relative to the second electrode 12 fixed to the support frame 13.

[0039] As the first electrode 11 and the second electrode 12 vibrate in the X direction, the area of ​​the surface where the comb-teeth portion 15 of the first electrode 11 and the comb-teeth portion 16 of the second electrode 12 face each other increases or decreases. As a result, the area of ​​the portion where the first electrode 11 and the second electrode 12 face each other changes, the induced charge generated by the electret also changes, and the potential difference between the first electrode 11 and the second electrode 12 changes to generate an electromotive force, thereby generating electricity through the vibration power generation element 10.

[0040] The vibration power generating element 10 converts vibration energy of the environment in which the vibration power generating device 100 is installed into electrical energy, thereby generating AC power.

[0041] Of the two output lines for outputting the AC voltage from the vibration power generation element 10, the output line W2 connected to the second electrode 12 and the output line W3 connected to the second electrode 12 are connected to the output line W4 connected to the second electrode 12. Figure 1 The output line W1 is connected to the input portion of the negative half-wave rectifier circuit 20, and the other output line W1 connected to the first electrode 11 is grounded. In addition, the output line W1 is also connected to the ground of the negative half-wave rectifier circuit 20 (the ground of the power supply circuit 50) via the ground.

[0042] The negative half-wave rectifier circuit 20 includes a first diode D1 whose cathode is connected to one end of the vibration power generation element 10, and a second diode D2 whose anode is connected to one end of the vibration power generation element 10 and the cathode of the first diode D1. The input portion of the negative half-wave rectifier circuit 20 is the cathode of the first diode D1 and the anode of the second diode D2. The output portion of the negative half-wave rectifier circuit 20 is the anode of the first diode D1.

[0043] When the AC voltage input from the second electrode 12 of the vibration power generating element 10 to the negative half-wave rectifier circuit 20 via the output line W2 is a positive voltage, it flows to the ground side through the second diode D2 as a current with almost no resistance. Therefore, only the negative voltage component of the AC voltage input to the negative half-wave rectifier circuit 20 is output from the negative half-wave rectifier circuit 20 through the first diode D1.

[0044] The anode of the first diode D1 as the output portion of the negative half-wave rectifier circuit 20 is connected to one end of the first capacitor C1, and the other end of the first capacitor C1 is grounded. Negative power output from the negative half-wave rectifier circuit 20 is stored in the first capacitor C1 and supplied from the first capacitor C1 to the inversion chopper circuit 30.

[0045] The first capacitor C1 smoothes the output power from the negative half-wave rectifier circuit 20 as a pulse output in terms of time, so that the power can be supplied to the inversion chopper circuit 30 in a stable manner, thereby improving the power transmission efficiency of the inversion chopper circuit 30.

[0046] Figure 3 1 is a diagram showing an overview of the operating principle of the vibration power generating element 10. Figure 3 One of the reasons why the vibration power generator 100 according to the first embodiment has high energy conversion efficiency will be described.

[0047] Figure 3 (a) to (c) indicate Figure 3 The comb-teeth portion 15 of the first electrode 11 and the comb-teeth portion 16 of the second electrode 12 are shown in FIG. Figure 1 In the case of relative movement in the X direction. Figure 3 In the description, for simplicity, the comb-tooth portion 15 of the first electrode 11 is referred to as the first electrode 15 , and the comb-tooth portion 16 of the second electrode 12 is referred to as the second electrode 16 .

[0048] Figure 3 (a) shows a state where the first electrode 15 and the second electrode 16 face each other at a predetermined portion. In a region 17 on the surface of the second electrode 16 facing the first electrode 15, an electret having negative charges 60 is formed.

[0049] The negative charge 60 induces positive charge 62 on the surface of the first electrode 15 facing the second electrode 16. On the other hand, the negative charge 60 of the region 17 induces positive charge 61 inside the second electrode 16 in the portion of the second electrode 16 not facing the first electrode 15.

[0050] The positive charges 62 induced in the first electrode 15 and the negative charges 60 of the electret on the surface of the second electrode 16 form an electric field E0 at the facing portion of the first electrode 15 and the second electrode 16 .

[0051] Figure 3 The resistor R in (a) represents the power supply circuit 50 and the external load R0 that connect the vibration power generating element 10 as a resistor. When the vibration power generating element 10 vibrates in the electric field E0, a voltage generated by a change in the electrostatic capacitance between the first electrode and the second electrode is applied to the resistor R0. Figure 3 In the examples shown in (b) and (c), the output voltage of the vibration power generation element 10 is proportional to the vibration of the first electrode 15 and the second electrode 16. Figure 3 There are increases and decreases compared to the example shown in (a).

[0052] Figure 3 (b) shows that Figure 3 In the state shown in (a), the first electrode 15 and the second electrode 16 start to move relative to each other in the X direction, and the area of ​​the portion where the first electrode 15 and the second electrode 16 face each other is equal to Figure 3 is reduced compared to the state shown in (a).

[0053] exist Figure 3 In the state shown in (b), Figure 3 Compared to the state shown in (a), the positive charges 62 on the surface of the first electrode 15 induced by the negative charges 60 on the surface of the second electrode 16 decrease, and the positive charges 61 in the second electrode 16 induced by the negative charges 60 increase.

[0054] Therefore, due to the vibration of the electrode Figure 3 The state change of (a) is Figure 3 (b) When the Figure 3 In (a), part of the positive charge 62 induced in the first electrode 15 becomes a current I1 and moves from the first electrode 15 to the second electrode 16 via the resistor R (more precisely, the electrons move from the second electrode 16 to the first electrode 15). Therefore, the first electrode 15 has a positive potential relative to the second electrode 16.

[0055] However, the movement of the charge is blocked by the resistance of the resistor R, so that a positive residual charge 64 remains in the first electrode 15, and a positive charge missing portion 63 is generated in a part of the second electrode 16 facing the negative charge 60. The positive residual charge 64 and the positive charge missing portion 63 make the electric field E1 of the facing portion of the first electrode 15 and the second electrode 16 larger than Figure 3 (a) The electric field E0 increases.

[0056] Figure 3 (c) indicates that Figure 3In the state shown in (a), the first electrode 15 and the second electrode 16 start to move relative to each other in the X direction, and the area of ​​the portion where the first electrode 15 and the second electrode 16 face each other is equal to Figure 3 The value is larger than that of the state shown in (a).

[0057] exist Figure 3 In the state shown in (c), Figure 3 Compared to the state shown in (a), the positive charges 62 on the surface of the first electrode 15 induced by the negative charges 60 increase, and the positive charges 61 in the second electrode 16 induced by the negative charges 60 decrease.

[0058] Therefore, due to the vibration of the electrode Figure 3 The state change of (a) is Figure 3 When the state (c) is Figure 3 Part of the positive charge 61 induced in the second electrode 16 in (a) becomes a current I2 and moves from the second electrode 16 to the first electrode 15 via the resistor R (more precisely, the electrons move from the first electrode 15 to the second electrode 16). Therefore, the first electrode 15 becomes a negative potential relative to the second electrode 16.

[0059] However, the movement of the charge is blocked by the resistance of the resistor R, so that a positive residual charge 65 remains in the second electrode 16, and a positive charge missing portion 66 is generated in a portion of the first electrode 15 facing the negative charge 60. The positive residual charge 65 and the positive charge missing portion 66 cause the electric field E2 of the facing portion of the first electrode 15 and the second electrode 16 to be equal to the electric field E2 of the first electrode 15 and the second electrode 16. Figure 3 The electric field E0 is weaker than that in (a).

[0060] In this way, when the electric field E2 is weakened, the power generation efficiency of the vibration power generation element 10 is reduced. Therefore, if power is obtained from the vibration power generation element 10 when the electric field E2 is weakened, the electrical damping is reduced, and the conversion speed from mechanical energy to electrical energy is slowed down, so the energy (kinetic energy) of the environmental vibration accumulated in the second electrode 16 as the movable electrode is not efficiently converted into electrical energy and is wasted.

[0061] In the power supply circuit 50 and the vibration power generating device 100 of the first embodiment, as Figure 1 As shown in FIG. 1 , the second electrode 12 of the vibration power generating element 10 is connected to the negative half-wave rectifier circuit 20 via the output line W2. Figure 3 As shown in the example (C), when the second electrode 12 of the vibration power generating element 10 is at a positive potential relative to the first electrode 11, the second diode D2 of the negative half-wave rectifier circuit 20 is forward biased, so that the current generated by the vibration power generating element 10 can pass through the second diode D2 and flow from the second electrode 12 to the first electrode 11 with almost no resistance.

[0062] Therefore, in the power supply circuit 50 and the vibration power generating device 100 of the first embodiment, it is possible to prevent the Figure 3 (a) to Figure 3 The electric field E2 is weakened when the first electrode 15 and the second electrode 16 move relative to each other as shown in (c), so that high power generation efficiency can be obtained.

[0063] It seems that the current flows from the second electrode 12 to the first electrode 11 through the second diode D2, thereby wasting the generated electric energy. However, the resistance of the current flowing through the second diode D2 in the forward direction is substantially zero, and the total amount of the current flowing is the amount of charge induced in the first electrode 11 and the second electrode 12, and the upper limit is determined, so the amount of lost electric energy ΔEG2, that is, (resistance)×(current)×(current) is also small.

[0064] Figure 4 The power generation output when the negative half-wave rectifier circuit 20 of the present embodiment is used is compared with the power generation output when a conventional full-wave rectifier circuit is used.

[0065] Figure 4 (a) shows the relationship between the power generation output (electric power) P11 of the negative half-wave rectifier circuit 20 of this embodiment and time t (horizontal axis), Figure 4 (b) shows the relationship between the power generation output (power) P21 of the conventional full-wave rectifier circuit and time t (horizontal axis). The vertical axes of both diagrams are the output power P.

[0066] When a conventional full-wave rectifier circuit such as a diode bridge type is used, the sinusoidal power (voltage) induced between the first electrode and the second electrode of the vibration power generating element accompanying the relative vibration of the electrodes passes through the full-wave rectifier circuit, and the negative voltage is inverted to positive, and the power P21 substantially equal to the absolute value of the sinusoidal wave is output. The time between adjacent peaks in the time variation of the power P21 is half the vibration period of the vibration power generating element.

[0067] on the other hand, Figure 4 The output P11 of the negative half-wave rectifier circuit 20 of the present embodiment shown in (a) only outputs a state where the first electrode 11 is induced as a positive potential and the second electrode 12 is induced as a negative potential in the sinusoidal power (voltage) induced between the first electrode 11 and the second electrode 12. That is, only the negative part of the sinusoidal voltage is output, so the number of peaks is half compared to the output P21 when the conventional full-wave rectifier circuit is used.

[0068] However, in the case of a vibration power generation element, the energy of the vibration applied from the outside is equal to the sum of the mechanical energy lost as air resistance and friction and the electrical energy generated by the vibration power generation element. Therefore, if the energy of the vibration applied from the outside and the mechanical energy lost are equal, the total amount of electrical energy obtained is fixed regardless of the number of times (frequency) the electrical energy is obtained.

[0069] Therefore, the magnitude (power) of a peak value of the output P11 of the negative half-wave rectifier circuit 20 of the present embodiment is larger than a peak value of the conventional output P21. In addition, without considering the weakening of the electric field E2, the time average P10 of the output power of the negative half-wave rectifier circuit 20 of the present embodiment is equal to the time average P20 of the output power of the device using the conventional full-wave rectifier circuit.

[0070] In addition, if the weakening of the electric field E2 mentioned above is taken into account, in a device using an existing full-wave rectifier circuit, the weakening of the electric field E2 cannot be avoided, resulting in a reduction in power generation efficiency. Therefore, the time average P10 of the output power of the negative half-wave rectifier circuit 20 of this embodiment is higher than the time average of the output power of the existing full-wave rectifier circuit.

[0071] As described above, in this embodiment, the power from the vibration power generating element 10 is input through the negative half-wave rectifier circuit 2, so the power generation efficiency of the vibration power generating element 10 can be improved. However, the output of the negative half-wave rectifier circuit 2 is a negative voltage, which is sometimes not suitable for general use.

[0072] Therefore, in this embodiment, the negative voltage power output from the negative half-wave rectifier circuit 20 is input to the inversion chopper circuit 30, and the negative voltage power is inverted into positive voltage power by the inversion chopper circuit 30 and then output.

[0073] When the switch element T1 such as a MOS transistor for controlling the chopping timing is turned on, the electric energy of the negative voltage output output from the negative half-wave rectifier circuit 20 and input to the inversion chopper circuit 30 is temporarily stored in the coil L1. Then, when the switch element T1 is turned off, the energy stored in the coil L1 is released as a current due to the self-inductance of the coil L1 and is output to the subsequent stage ( Figure 1 The circuit on the right side of the diagram.

[0074] The power input from the negative half-wave rectifier circuit 20 to the inverting chopper circuit 30 is a negative voltage. Therefore, when the switch element T1 is turned on, the current flows from the ground side ( Figure 1 Since the switching element T1 side of the rectifying diode D5 is an anode, when the switching element T1 is turned on, it is reverse biased and no current flows.

[0075] When the switch element T1 is turned off, the energy stored in the coil 1 is converted into a current flowing from the ground side to the rectifier diode D5 side in the coil L1 due to the self-inductance of the coil L1. At this time, the end of the coil L1 connected to the rectifier diode D5 is at a positive potential relative to the ground. Therefore, the rectifier diode D5 becomes forward biased, so the current is output to the voltage conversion circuit 40 through the rectifier diode D5.

[0076] As described above, the negative voltage power is converted into the positive voltage power by the inversion chopper circuit 30 .

[0077] The cathode of the rectifying diode D5 as the output portion P3 of the inverting chopper circuit 30 is connected to one end P3 of the second capacitor C2, and the other end of the second capacitor C2 is grounded. The positive power output from the inverting chopper circuit 30 is stored in the second capacitor C2 and output from the second capacitor C2 to the input portion Vin of the voltage conversion circuit 40.

[0078] The second capacitor C2 smoothes the output power from the inversion chopper circuit 30 as a pulse output in terms of time, so that the power can be supplied to the conversion circuit 40 in a stable manner, and the power transmission efficiency of the voltage conversion circuit 40 can be improved.

[0079] The voltage conversion circuit 40 converts the voltage output from the inversion chopper circuit 30 and input to the input part Vin so that the voltage output from the output part Vout to the external load R0 becomes a positive predetermined fixed value. A common switching regulation type DC / DC converter can be used for the voltage conversion circuit 40. A third capacitor C3 is provided between the output part Vout of the voltage conversion circuit 40 and the ground, thereby further smoothing the output voltage from the voltage conversion circuit 40.

[0080] In addition, the voltage conversion circuit 40 is used to convert the positive power as the output of the inversion chopper circuit 30 into a voltage suitable for the external load R0. Therefore, when the voltage suitable for the external load R0 is consistent with the output voltage of the inversion chopper circuit 30, or when the external load R0 itself has a function of converting the voltage, the power supply circuit 50 does not need to include the voltage conversion circuit 40. In this case, when the external load R0 has capacitors equivalent to the second capacitor C2 and the third capacitor C3, the power supply circuit 50 does not need to include the second capacitor C2 and the third capacitor C3.

[0081] As an example, the input portion P1 of the inversion chopper circuit 30 is connected to the source of the switching element T1 formed of an nMOS transistor (nMOSFET).

[0082] In the inverting chopper circuit 30 , the switching element T1 is controlled to be turned on and off by a control circuit 35 including a Zener diode D6 included in the inverting chopper circuit 30 , resistor elements R2 and R3 constituting a voltage divider, a comparator circuit CP, and the like.

[0083] The power generation efficiency of the vibration power generation element 10 depends on the voltage of the first capacitor C1 for storing power from the vibration power generation element 10. That is, when the first capacitor C1 is charged and the absolute value of the voltage becomes too high (negatively large in this embodiment), the resistance of the first capacitor C1 when viewed from the vibration power generation element 10 increases, so the power generation efficiency of the vibration power generation element 10 decreases. Even if the absolute value of the voltage of the first capacitor C1 decreases too much (negatively decreases in this embodiment), the power generation efficiency of the vibration power generation element 10 decreases.

[0084] Therefore, the control circuit 35 controls the switching element T1 to be turned on and off according to the voltage of the first capacitor C1 (the voltage of the input part P1 of the inversion chopper circuit 30), and maintains the voltage of the first capacitor C1 in a predetermined range near the optimal voltage V0 at which the power generation efficiency of the vibration power generating element 10 is the highest. Specifically, the control circuit 35 controls so that the voltage of the first capacitor C1 becomes between the first reference negative voltage V1 which is a voltage lower than the optimal voltage V0 (negative side) and the second reference negative voltage V2 which is a voltage higher than the optimal voltage V0 (positive side).

[0085] In addition, there is a general concern that when the switch element T1 is turned on, the charge accumulated in the second capacitor C2 flows back to the first capacitor C1, and the voltage of the first capacitor C1 changes. However, the present embodiment includes a reverse chopper circuit 30 between the first capacitor C1 and the second capacitor C2, and the reverse chopper circuit 30 includes a rectifier diode D5 at the output portion. Therefore, the current from the second capacitor C2 with a positive voltage to the first capacitor C1 with a negative voltage is cut off by the rectifier diode D5, so the voltage of the first capacitor C1 does not change due to the voltage of the second capacitor C2. As a result, the switch element T1 can be controlled with high precision.

[0086] Next, the control circuit 35 will be described.

[0087] One end of the resistor R1 is connected to the input portion P1 of the inverting chopper circuit 30, the other end of the resistor R1 is connected to the anode of the Zener diode D6, and the cathode of the Zener diode D6 is grounded. In addition, one end of the resistor R2 is connected to the input portion P1, the other end of the resistor R2 is connected to one end of the resistor R3, and the other end of the resistor R3 is grounded.

[0088] As described above, one end of the first capacitor C1 is connected to the input portion P1 of the inverting chopper circuit 30, and the other end of the first capacitor C1 is grounded, so the cathode of the Zener diode D6 is also connected to the other end of the first capacitor C1. The resistor element R2 and the resistor element R3 constitute a voltage divider that divides the voltage applied to both ends of the first capacitor C1 (the voltage of the input portion P1 with respect to the ground).

[0089] The voltage of the voltage divider P2, which is the connection between the resistor R2 and the resistor R3, is the voltage obtained by dividing the voltage of the input part P1, and is therefore proportional to the voltage of the input part P1. On the other hand, if the input part P1 is a negative voltage with respect to the breakdown voltage of the Zener diode D6, the voltage of the anode of the Zener diode D6 is a negative fixed value (the breakdown voltage of the Zener diode D6).

[0090] Therefore, by inputting the above two voltages to the comparator circuit CP for voltage comparison, it is possible to determine whether the voltage of the input part P1 (the voltage of the first capacitor C1 ) is above or below the optimal voltage V0 that maximizes the power generation efficiency of the vibration power generating element 10 .

[0091] In order to make this judgment, the resistance values ​​of the resistor elements R2 and R3 constituting the voltage divider are set so that when the voltage of the input part P1 of the inverting chopper circuit 30 (the voltage of the first capacitor C1) is the optimal voltage V0, the voltage of the voltage divider P2 is substantially equal to the breakdown voltage of the Zener diode D6. In order to make this setting easier, as shown in FIG. Figure 1 As shown in FIG. 1 , it is desirable that at least one of the resistor elements R2 and R3 (in Figure 1 The resistor element R2 is a variable resistor.

[0092] Furthermore, instead of the resistor elements, the resistor element R2 and the resistor element R3 may be capacitors.

[0093] The voltage of the anode of the Zener diode D6 is input to the negative input (first input) of the comparator circuit CP. On the other hand, the voltage of the voltage divider P2 is input to the positive input (second input) via the input feedback resistor R4, and the output of the comparator circuit CP is input via the output feedback resistor R5.

[0094] Thus, the comparator circuit CP functions as a circuit with hysteresis. That is, when the voltage of the voltage divider P2 changes from the positive voltage side to the negative voltage side, when the voltage of the voltage divider P2 reaches a predetermined first voltage lower than the voltage input to the negative side input (more to the negative side), the output of the comparator circuit CP changes from zero (ground potential) to negative. On the other hand, when the voltage of the voltage divider P2 changes from the negative voltage side to the positive voltage side, when the voltage of the voltage divider P2 reaches a predetermined second voltage higher than the voltage input to the negative side input (positive side), the output of the comparator circuit CP changes from negative to zero (ground potential).

[0095] In addition, the resistance value of the input side feedback resistor R4 and the resistance value of the output side feedback resistor R5 are set so that when the voltage of the first capacitor C1 is the first reference negative voltage V1 and the second reference negative voltage V2, the voltage of the voltage divider P2 is the first voltage and the second voltage, respectively. It is desirable that the resistance values ​​of the resistor elements R2 and R3 are set at the same time when setting this.

[0096] The output of the comparator circuit CP is input to the gate of a pMOS transistor (PMOSFET) T2.

[0097] If the output of the comparator circuit CP is negative, the transistor T2 is turned on, and due to the voltage drop caused by the current flowing through the resistor R8, the gate voltage of the switch element T1 as an nMOS transistor becomes higher (to the positive side) than the source voltage of the switch element T1, and the switch element T1 is turned on. In addition, the preferred resistor R8 is a variable resistor so that the amount of voltage drop can be adjusted.

[0098] On the other hand, if the output of the comparator circuit CP is zero, the transistor T2 is turned off, resulting in that the gate voltage of the switch element T1 as an nMOS transistor becomes equal to the source voltage of the switch element T1, and thus the switch element T1 is turned off.

[0099] The resistor R7 disposed between the gate of the transistor T2 and the ground is a resistor element for discharging the output of the comparator circuit CP temporarily accumulated in the gate of the transistor T2 to the ground, and is preferably a variable resistor in order to adjust the discharge time.

[0100] The second Zener diode D7 is an element for disconnecting the second Zener diode D7 and the resistor R8 to turn off the switch element T1 when the absolute value of the voltage of the input portion P1 is small and the operation of the transistor T2 is unstable.

[0101] Figure 5The figure shows the time change of the voltage VP1 of the input part P1 (the voltage of the first capacitor C1 ) of the inversion chopper circuit 30 of the vibration power generating device 100 according to the present embodiment. The vertical axis represents the voltage and the horizontal axis represents the time.

[0102] When the vibration power generating element 10 starts to generate power, negative charges are accumulated in the first capacitor C1 , so that the voltage VP1 of the first capacitor C1 gradually increases in a negative direction.

[0103] When the voltage VP1 of the first capacitor C1 reaches the first reference negative voltage V1, the voltage of the voltage divider P2 proportional to the voltage VP1 reaches the above-mentioned first voltage, and the control circuit 35 turns on the switch element T1. As a result, the charge (electric energy) accumulated in the first capacitor C1 is discharged, and the current flows through the coil L1 as magnetic energy, and is accumulated in the coil L1. Even if the switch element T1 is turned on, a negative current flows from the vibration power generation element 10 to the first capacitor C1 via the negative half-wave rectifier circuit 20. However, the current flowing out of the coil L1 is greater than the current flowing in from the negative half-wave rectifier circuit 20, so the voltage VP1 of the first capacitor C1 decreases negatively (changes in the positive direction).

[0104] Soon after the switch element T1 is turned on, the voltage VP1 of the first capacitor C1 reaches the second reference negative voltage V2 from the negative side, and the voltage of the voltage divider P2 proportional to the voltage VP1 also reaches the second voltage. Then, the control circuit 35 turns off the switch element T1, and the discharge from the first capacitor C1 to the coil L1 stops. Since the negative current continues to flow from the vibration power generating element 10 to the first capacitor C1 via the negative half-wave rectifier circuit, the voltage VP1 of the first capacitor C1 changes to the negative side again and reaches the first reference negative voltage V1.

[0105] Then, by repeating the above cycle, the voltage VP1 of the first capacitor C1 is maintained between the first reference negative voltage V1 and the second reference negative voltage V2, that is, maintained near the optimal voltage V0 at which the power generation efficiency of the vibration power generating element 10 is the highest. Thus, the vibration power generating device 100 and the power supply circuit 50 of this embodiment can achieve high power generation efficiency.

[0106] (Second Embodiment)

[0107] Figure 6 This is a schematic diagram showing the schematic configuration of a power supply circuit 50a and a vibration power generating device 100a according to a second embodiment of the present invention. Most of the configuration of the second embodiment is the same as that of the first embodiment, and therefore the same reference numerals are used for the same configurations and description thereof is omitted.

[0108] In the second embodiment, the structures of the vibration power generating element 10 a and the negative half-wave rectifier circuit 20 a are different from those of the first embodiment, but the other structures are the same as those of the first embodiment.

[0109] Figure 7 1 is a schematic diagram showing a vibration power generating element 10a included in a vibration power generating device 100a according to the second embodiment. The vibration power generating element 10a has the following structure: Figure 4 The vibration power generating element 10 is turned upside down and the other vibration power generating element 10 is arranged in parallel at the lower side in the figure with the spacing holding portion 14.

[0110] The second electrode 12a and the second electrode 12b, which are two fixed electrodes, are fixed to the inner sides of the ends of the support frame 13 on the +X side and the -X side, respectively. On the other hand, the first electrode 11a and the first electrode 11b, which are two movable electrodes, are provided on the +X side and the -X side, respectively, of the electrode holding portion 14a constituting the holding portion 14. Therefore, similarly to the first embodiment described above, when the holding portion 14 vibrates due to vibration from the outside, the first electrodes 11a and 11b vibrate in the X direction relative to the second electrodes 12a and 12b. Negatively charged electrets are formed in the areas 17a and 17b of the surfaces of the comb-tooth portions 16a and 16b of the second electrodes 12a and 12b, which face the comb-tooth portions 15a and 15b of the first electrodes 11a and 11b, respectively.

[0111] Negative half-wave rectifier circuit 20 is Figure 6 The structure shown is composed of two parallel configurations. Figure 1 The negative half-wave rectifier circuit 20 shown in FIG. The output line W2a connected to the second electrode 12a is connected to the cathode of the first diode D1 and the anode of the second diode D2, which are the input portion of the negative half-wave rectifier circuit 20, as in the first embodiment described above. In addition, the output line W2b connected to the second electrode 12b is connected to the cathode of the third diode D3 and the anode of the fourth diode D4, which are the other input portion of the negative half-wave rectifier circuit 20.

[0112] The output line W1 connected to the first electrodes 11 a and 11 b is grounded similarly to the first embodiment described above, and is connected to the cathode of the second diode D2 and the anode of the fourth diode D4 .

[0113] The anode of the first diode D1 and the anode of the third diode D3 are output portions of the negative half-wave rectification circuit 20 .

[0114] The negative half-wave rectifier circuit 20a of the second embodiment looks like a diode bridge type full-wave rectifier circuit, but it is actually two negative half-wave rectifier circuits arranged in parallel, not a full-wave rectifier circuit. For the voltages input from the pair of output lines W2a and W2b, respectively, only when the voltage input from the output line W1 is negative, the power is output to the output unit, and when the input voltage is positive, the current flows to the ground through the second diode D2 and the fourth diode D4.

[0115] Thus, the negative half-wave rectifier circuit 20a functions as a half-wave rectifier circuit that passes only the negative voltage portion of the AC voltage. Therefore, by combining the vibration power generating element 10a and the negative half-wave rectifier circuit 20a, it is possible to prevent the weakening of the electric field E2 in the vibration power generating element 10a, and obtain high power generation efficiency, as in the first embodiment described above.

[0116] Furthermore, since the vibration power generating element 10a included in the vibration power generating device 100a of the second embodiment has two vibration power generating elements 10 of the first embodiment arranged in parallel as described above, higher power generating efficiency can be obtained than that of the vibration power generating device 100 of the first embodiment.

[0117] In any of the first and second embodiments, the vibration power generating elements 10 and 10a are configured such that the first electrodes 11, 11a, and 11b are movable electrodes and the second electrodes 12, 12a, and 12b are fixed electrodes, but the present invention is not limited to this structure. In other words, the first electrodes 11, 11a, and 11b may be fixed electrodes and the second electrodes 12, 12a, and 12b may be movable electrodes.

[0118] Alternatively, an electret having positive charge may be formed on the surface of the first electrodes 11, 11a, 11b instead of forming an electret having negative charge on the surface of the second electrodes 12, 12a, 12b. In this case, as described above, it is possible to prevent power from being obtained from the vibration power generating element 10 in a state where the electric field E2 between the two electrodes is weakened, thereby improving power generation efficiency.

[0119] Each diode (D1 to D4) in the negative half-wave rectifier circuits 20 and 20a may have a structure in which a plurality of diodes are connected in series to increase the withstand voltage.

[0120] In addition, the Zener diode D6 in the control circuit 35 in the inversion chopper circuit 30 may be a structure in which a plurality of Zener diodes are connected in series.

[0121] In the above-described embodiments, the cathode of the Zener diode D6 in the control circuit 35 in the inversion chopper circuit 30 is directly grounded, but the present invention is not limited thereto and the cathode may be grounded via a resistor element.

[0122] However, in this case, the voltage input to the negative input (first input) of the comparator circuit CP is displaced to the negative side by the voltage drop caused by the current flowing through the resistor element relative to the breakdown voltage of the Zener diode D6. Therefore, it is desirable to set the resistance values ​​of the resistor elements R2 and R3 so that the voltage of the voltage divider P2 input to the positive input (second input) of the comparator circuit CP is also displaced to the negative side to the same extent. In the case where the cathode of the Zener diode D6 is grounded via the resistor element, the resistor element R1 on the anode side can also be omitted.

[0123] The entire control circuit 35 in the inverting chopper circuit 30 is not limited to the above-mentioned structure, and may be other structures. For example, an A / D conversion circuit and a control logic circuit that convert the voltage of the input part P1 into a digital value may be used instead of the comparator circuit CP. In this case, the following structure may be used: when the voltage value after digital conversion is the above-mentioned first reference negative voltage V1 and second reference negative voltage V2, the control logic circuit turns the switch element T1 on and off.

[0124] (Effects of Embodiments)

[0125] (1) The power supply circuit 50, 50a of each of the above-mentioned embodiments and each of the modified examples is a power supply circuit that outputs the power input from the vibration power generating element 10, 10a to an external load, and comprises: a negative half-wave rectifier circuit 20, 20a, which half-wave rectifies the AC power input from the vibration power generating element 10, 10a into a negative voltage output; and an inverting chopper circuit 30, which inverts the negative voltage output from the negative half-wave rectifier circuit 20, 20a into a positive voltage output and outputs it.

[0126] With this structure, the vibration power generating elements 10 and 10 a can generate power efficiently, and the energy of environmental vibration can be efficiently converted into electrical energy.

[0127] (2) In (1), the structure is further provided with a voltage conversion circuit 40, which performs voltage conversion on the positive voltage output from the inverting chopper circuit 30 and outputs it to the external load, thereby enabling the power supply circuit 50 to output a voltage suitable for the external load R0, thereby enabling the power supply circuit 50 to be suitable for various external loads R0.

[0128] (3) In (1) or (2), the structure is to further include a first capacitor C1, one end of which is connected to the output part of the negative half-wave rectifier circuit 20, 20a, and the other end is grounded, so that the negative voltage output from the negative half-wave rectifier circuit 20, 20a is accumulated and output to the inverting chopper circuit 30, thereby being able to provide the electric power to the inverting chopper circuit 30 after being stabilized, and the efficiency of the electric power transmission of the inverting chopper circuit 30 can be improved.

[0129] (4) In (3), the structure is to further include a second capacitor C2, one end of which is connected to the output part of the inverting chopper circuit 30, and the other end is grounded, so as to accumulate the positive voltage output from the inverting chopper circuit 30 and output it to the voltage conversion circuit 40, thereby being able to provide the power to the voltage conversion circuit 40 after being stabilized, and the efficiency of power transmission of the voltage conversion circuit 40 can be improved.

[0130] (5) In (4), the structure is further provided with a control circuit 35. When the voltage at one end of the first capacitor C1 is a first reference negative voltage, the control circuit 35 turns on the switch element T1 that controls the chopping timing in the inversion chopper circuit 30. When the voltage at one end of the first capacitor C1 becomes a second reference negative voltage that is closer to the positive side relative to the first reference negative voltage, the control circuit 35 turns off the switch element T1. As a result, the voltage of the first capacitor C1 can be maintained near the optimal voltage V0 at which the power generation efficiency of the vibration power generation element 10 is the highest, thereby further improving the power generation efficiency.

[0131] (6) In (5), the control circuit 35 is further configured to include: a Zener diode D6, whose anode is disposed between one end and the other end of the first capacitor C1 with its anode facing the one end side of the first capacitor C1; a resistor element R1, which is disposed between the first capacitor C1 and the Zener diode D6; and voltage dividers R2 and R3, which are disposed between one end and the other end of the first capacitor C1 and divide the voltage at one end of the first capacitor C1 and the voltage at the other end of the first capacitor. The control circuit 35 turns on and off the switch element T1 according to the result of comparing the voltage applied to both ends of the Zener diode D6 with the output voltage of the voltage divider R2 and R3. Thus, the switch element T1 can be turned on and off accurately according to the voltage of the first capacitor C1. As a result, the voltage of the first capacitor C1 can be more accurately maintained near the optimal voltage V0, and the power generation efficiency can be further improved.

[0132] (7) In (6), one end of the resistor R1 is connected to one end of the first capacitor C1, and the other end is connected to the anode of the Zener diode D6, and the cathode of the Zener diode D6 is connected to the other end of the first capacitor, thereby making the voltage on the anode side of the Zener diode D6 equal to the breakdown voltage of the grounded Zener diode D6. Thus, the voltage applied to both ends of the Zener diode D6 and the output voltage of the voltage divider R2 and R3 can be easily compared, and the cost of the inverting chopper circuit 30 can be reduced.

[0133] (8) In (6) or (7), the control circuit 35 is further configured to include a comparator circuit CP, an input-side feedback resistor R4, and an output-side feedback resistor R5. The voltage of the anode of the Zener diode D6 is input to the first input of the comparator circuit CP, the output voltage of the voltage divider R2 and R3 is input to the second input of the comparator circuit CP via the input-side feedback resistor R4, and the output of the comparator circuit CP is input to the second input of the comparator circuit CP via the output-side feedback resistor R5. The switch element T1 is turned on and off according to the output of the comparator circuit CP, thereby realizing a low-power consumption control circuit 35 and supplying more power to the external load R0.

[0134] (9) The vibration power generating devices 100 and 100a of the above-mentioned embodiments and modifications include the power supply circuit 50 and 50a of any one of the above-mentioned (1) to (8), and the vibration power generating elements 10 and 10a that supply power to the power supply circuit 50 and 50a.

[0135] Through this structure, the energy of environmental vibration can be efficiently converted into electrical energy.

[0136] (10) In (9), the vibration power generating element 10, 10a is constructed such that the electrodes 12, 12a, 12b having a negative charge of an electret are connected to the input part of the negative half-wave rectifier circuit 20 of the power supply circuit 50, 50a, and the electrodes 11, 11a, 11b having no electret are connected to the ground in the power supply circuit 50, 50a, or the electrodes having no electret are connected to the input part of the negative half-wave rectifier circuit 20 of the power supply circuit 50, 50a, and the electrodes having a positive charge of an electret are connected to the ground of the power supply circuit 50, 50a. This can prevent the weakening of the electric field of the electret type vibration power generating element 10, 10a and obtain higher power generation efficiency.

[0137] Various embodiments and variations have been described above, but the present invention is not limited to these contents. In addition, each embodiment and variation can be applied separately or in combination. Other embodiments that can be considered within the scope of the technical idea of ​​the present invention are also included in the scope of the present invention.

[0138] The disclosures of the following priority basic applications are incorporated herein by reference.

[0139] Japanese Patent Application No. 2018-105435 (filed on May 31, 2018)

[0140] Description of Reference Numerals

[0141] 100, 100a: vibration power generation device; 10, 10a: vibration power generation element; 20, 20a: negative half-wave rectification circuit; 30: reverse chopper circuit; 35: control circuit; 40: voltage conversion circuit; C1: first capacitor; C2: second capacitor; C3: third capacitor; R0: external load; T1: switching element; CP: comparator circuit; D6: Zener diode.

Claims

1. A power supply circuit that outputs power input from a vibration power generation element to an external load, characterized in that: have: A negative half-wave rectifier circuit that performs half-wave rectification of the AC power input from the vibration power generating element into a negative voltage output; and an inverting chopper circuit that inverts the negative voltage output from the negative half-wave rectifier circuit into a positive voltage output and outputs the positive voltage, The above negative half-wave rectifier circuit comprises: a first diode connecting one of a pair of output lines for inputting the AC power to the negative half-wave rectifier circuit to an input portion of the inverting chopper circuit; a second diode electrically connecting one of the pair of output lines to the other, The second diode allows a current to flow from the one output line side to the other output line side. The electrode of the vibration power generating element having an electret having a negative charge is connected to the input portion of the negative half-wave rectifier circuit of the power supply circuit, and the electrode without an electret is connected to the ground in the power supply circuit, or The electrode of the vibration power generating element without an electret is connected to the input portion of the negative half-wave rectifier circuit of the power circuit, and the electrode with an electret having a positive charge is connected to the ground of the power circuit.

2. The power supply circuit according to claim 1, characterized in that: The power supply circuit further includes a voltage conversion circuit that converts the positive voltage output from the inversion chopper circuit and outputs the converted voltage to the external load.

3. The power supply circuit according to claim 1 or 2, characterized in that: The power supply circuit further includes a first capacitor having one end connected to the output portion of the negative half-wave rectifier circuit and the other end grounded, accumulating the negative voltage output from the negative half-wave rectifier circuit and outputting it to the inverting chopper circuit.

4. The power supply circuit according to claim 3, characterized in that: The power supply circuit further includes a second capacitor having one end connected to the output portion of the inverting chopper circuit and the other end grounded, and accumulating the positive voltage output from the inverting chopper circuit.

5. The power supply circuit according to claim 3, characterized in that: The power supply circuit also includes a control circuit. When the voltage at the one end of the first capacitor becomes a first reference negative voltage, the control circuit turns on the switch element for controlling the chopping timing in the inverting chopper circuit. When the voltage at the one end of the first capacitor becomes a second reference negative voltage that is closer to the positive side than the first reference negative voltage, the control circuit turns off the switch element for controlling the chopping timing in the inverting chopper circuit.

6. The power supply circuit according to claim 5, characterized in that: The control circuit has: a Zener diode, the anode of which faces the one end of the first capacitor and is arranged between the one end and the other end of the first capacitor; a resistor element disposed between the first capacitor and the Zener diode; and a voltage divider disposed between the one end and the other end of the first capacitor, and dividing a voltage at the one end of the first capacitor and a voltage at the other end of the first capacitor; The control circuit turns the switch element on and off according to a comparison result between a voltage applied across the Zener diode and an output voltage of the voltage divider.

7. The power supply circuit according to claim 6, characterized in that: One end of the resistor is connected to the one end of the first capacitor, and the other end is connected to the anode of the Zener diode. A cathode of the Zener diode is connected to the other end of the first capacitor.

8. The power supply circuit according to claim 6 or 7, characterized in that: The control circuit comprises a comparison circuit, an input side feedback resistor, and an output side feedback resistor. The voltage of the anode of the Zener diode is input to the first input of the comparison circuit. the output voltage of the voltage divider is input to a second input of the comparison circuit via the input-side feedback resistor, and the output of the comparison circuit is input to a second input of the comparison circuit via the output-side feedback resistor, The control circuit turns on and off the switch element according to the output of the comparison circuit.

9. A vibration power generation device, characterized in that: have: The power supply circuit according to any one of claims 1 to 8; and The vibration power generating element supplies electric power to the power supply circuit.

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