JP7014269B2 - Power circuit - Google Patents

Description

The present invention relates to a power supply circuit.

Patent Document 1 describes a bearing with a sensor that detects various physical quantities around the bearing by a sensor and wirelessly transmits the detection information to a receiving device. Patent Document 2 describes a micro power supply module including a decoupling capacitor.

Japanese Patent Application Laid-Open No. 2003-307435 Japanese Unexamined Patent Publication No. 2009-38950

If the voltage supplied to the load sensor fluctuates, the load may behave abnormally.

The present invention has been made in view of the above, and an object of the present invention is to provide a power supply circuit capable of suppressing the possibility that a load may operate abnormally.

The power supply circuit of the present disclosure for achieving the above object is a power supply circuit that supplies power to a load, and is a power supply IC that controls an output voltage applied to the load and the output voltage to which the load is connected. A decoupling capacitor connected between the output terminal on the high potential side and the reference potential, an output terminal on the low potential side of the output voltage to which the load is connected, and a terminal on the low potential side of the decoupling capacitor. A switch circuit provided in between is provided, and the power supply IC outputs a signal for controlling the switch circuit to an on state or an off state according to the output voltage.

Therefore, the switch circuit can be turned off according to the output voltage. As a result, it is possible to suppress the possibility that the load will behave abnormally.

As a desirable aspect of the present disclosure, the power supply IC is preset with a first voltage threshold and a second voltage threshold having a higher potential than the reference potential and a lower potential than the first voltage threshold. A voltage threshold comparison unit for controlling the switch circuit by comparing the output voltage with the first voltage threshold and the second voltage threshold is provided, and the voltage threshold comparison unit has the output voltage. When the output voltage is rising and is equal to or higher than the first voltage threshold, or when the output voltage is falling and equal to or higher than the second voltage threshold, the signal for controlling the switch circuit to be turned on is transmitted to the switch. The switch circuit is output to the circuit when the output voltage is rising and is smaller than the first voltage threshold, or when the output voltage is falling and smaller than the second voltage threshold. It is preferable to output a signal for controlling the off state to the switch circuit.

Therefore, when the output voltage is rising and smaller than the first voltage threshold value, or when the output voltage is falling and smaller than the second voltage threshold value, the switch circuit is turned off. Therefore, the power of the decoupling capacitor is not supplied to the load. Therefore, the load cannot operate. As a result, it is possible to suppress the possibility that the load will behave abnormally.

As a desirable aspect of the present disclosure, the switch circuit is an N-channel MOS type transistor, and the source-drain path of the transistor has an output terminal on the low potential side and a terminal on the low potential side of the decoupling capacitor. It is preferable that it is inserted between.

Therefore, it is possible to prevent the potential applied to the input terminal on the high potential side of the load from dropping.

The power supply IC preferably outputs the signal to the gate of the transistor.

Therefore, it is possible to eliminate the need to provide a separate circuit for controlling the transistor.

A bearing with a sensor includes a bearing body having a relatively rotating outer ring and an inner ring, a sensor that detects a physical amount or a chemical amount, a generator that generates power based on the relative rotation between the outer ring and the inner ring, and the above. The power supply circuit includes a power supply circuit that outputs the power generated by the generator to the sensor, and the power supply circuit lowers the booster voltage boosted by the booster circuit and the booster circuit that boosts the generated voltage of the generator. A step-down circuit, a decoupling capacitor connected between the step-down voltage stepped down by the step-down circuit and a reference potential, a terminal on the high potential side of the decoupling capacitor, and an output terminal on the high potential side are connected. The output line on the low potential side connecting the output line on the high potential side, the terminal on the low potential side of the decoupling capacitor, and the output terminal on the low potential side, and the source-drain path are on the low potential side. The transistor inserted in the output line or the output line on the high potential side is compared with the boosted voltage and the set boosted voltage threshold, and when the boosted voltage is equal to or higher than the boosted voltage threshold, the transistor is used. The boost voltage threshold is output to the gate of the transistor to control the on state, and when the boost voltage is smaller than the boost voltage threshold, the signal to control the transistor to the off state is output to the gate of the transistor. It is equipped with a comparison unit.

Therefore, when the boost voltage of the boost circuit is smaller than the boost voltage threshold value, the transistor is turned off. Therefore, the power of the decoupling capacitor is not supplied to the sensor. Therefore, the sensor cannot operate. As a result, the possibility that the sensor operates abnormally can be suppressed.

As a preferred embodiment of the sensor-equipped bearing, it is preferable that the source-drain path of the transistor is inserted into the output line on the low potential side.

Therefore, it is possible to prevent the potential applied to the input terminal on the high potential side of the sensor from dropping.

As a desirable embodiment of the bearing with a sensor, a part of the booster circuit, a part of the step-down circuit, and the booster voltage threshold comparison unit are included in the power supply IC, and the signal is transmitted from the power supply IC to the power supply IC. It is preferable that the output is to the gate of the transistor.

Therefore, it is possible to eliminate the need to provide a separate circuit for controlling the transistor.

As a desirable embodiment of the bearing with a sensor, in the power supply circuit, the closed circuit voltage, which is the generated voltage when the booster circuit is operating, is the open circuit voltage, which is the generated voltage when the booster circuit is not operating. It is preferable to further include a maximum power point tracking control unit that controls the booster circuit so that the voltage is multiplied by the circuit voltage and the set ratio.

Therefore, electric power can be suitably obtained from the generator.

Further, the bearing with a sensor includes a bearing body having a relatively rotating outer ring and an inner ring, a sensor for detecting a physical amount or a chemical amount, and a generator that generates power based on the relative rotation between the outer ring and the inner ring. A power supply circuit that outputs the power generated by the generator to the sensor, and the power supply circuit includes a booster circuit that boosts the generated voltage of the generator and a boosted voltage boosted by the booster circuit. A step-down circuit for step-down, a decoupling capacitor connected between the step-down voltage stepped down by the step-down circuit and a reference potential, a terminal on the high potential side of the decoupling capacitor, and an output terminal on the high potential side. The low potential side output line connecting the high potential side output line, the low potential side terminal of the decoupling capacitor, and the low potential side output terminal, and the source-drain path are the low. The transistor inserted in the output line on the potential side or the output line on the high potential side is compared with the step-down voltage and the set step-down voltage threshold, and when the step-down voltage is equal to or higher than the step-down voltage threshold, the step-down voltage is described. A step-down voltage threshold that outputs a signal that controls the transistor to the on state to the gate of the transistor, and outputs a signal that controls the transistor to the off state when the step-down voltage is smaller than the step-down voltage threshold value. A comparison unit (for example, a nanopower control unit 215 according to the embodiment) is provided.

Therefore, when the step-down voltage of the step-down circuit is smaller than the step-down voltage threshold value, the transistor is turned off. Therefore, the power of the decoupling capacitor is not supplied to the sensor. Therefore, the sensor cannot operate. This can reduce the possibility that the sensor will operate abnormally.
The power supply circuit is a power supply circuit that outputs the power generated by the generator to the sensor, and includes a booster circuit that boosts the generated voltage of the generator and a step-down circuit that steps down the boosted voltage boosted by the booster circuit. , A high potential connecting a decoupling capacitor connected between the step-down voltage stepped down by the step-down circuit and a reference potential, a terminal on the high potential side of the decoupling capacitor, and an output terminal on the high potential side. The output line on the low potential side connecting the output line on the side, the terminal on the low potential side of the decoupling capacitor, and the output terminal on the low potential side, and the source-drain path are the output lines on the low potential side. Alternatively, the transistor inserted in the output line on the high potential side is compared with the boosted voltage and the set boosted voltage threshold, and when the boosted voltage is equal to or higher than the boosted voltage threshold, the transistor is turned on. A boosted voltage threshold comparison unit that outputs a signal to be controlled to the gate of the transistor and outputs a signal to control the transistor to the off state when the boosted voltage is smaller than the boosted voltage threshold. , Equipped with.
Therefore, when the boost voltage of the boost circuit is smaller than the boost voltage threshold value, the transistor is turned off. Therefore, the power of the decoupling capacitor is not supplied to the sensor. Therefore, the sensor cannot operate. This can reduce the possibility that the sensor will operate abnormally.
Further, the power supply circuit is a power supply circuit that outputs the power generated by the generator to the sensor, and is a booster circuit that boosts the generated voltage of the generator and a step-down that lowers the boosted voltage boosted by the booster circuit. The circuit, a decoupling capacitor connected between the step-down voltage stepped down by the step-down circuit and a reference potential, a terminal on the high potential side of the decoupling capacitor, and an output terminal on the high potential side are connected. The output line on the low potential side connecting the output line on the high potential side, the terminal on the low potential side of the decoupling capacitor, and the output terminal on the low potential side, and the source-drain path are on the low potential side. The transistor inserted in the output line or the output line on the high potential side is compared with the step-down voltage and the set step-down voltage threshold, and when the step-down voltage is equal to or higher than the step-down voltage threshold, the transistor is inserted. A step-down voltage threshold comparison in which a signal for controlling the on state is output to the gate of the transistor, and a signal for controlling the transistor to the off state is output to the gate of the transistor when the step-down voltage is smaller than the step-down voltage threshold value. It has a part and.
Therefore, when the step-down voltage of the step-down circuit is smaller than the step-down voltage threshold value, the transistor is turned off. Therefore, the power of the decoupling capacitor is not supplied to the sensor. Therefore, the sensor cannot operate. This can reduce the possibility that the sensor will operate abnormally.

According to the present invention, it is possible to provide a power supply circuit capable of suppressing the possibility that the load will operate abnormally.

FIG. 1 is a perspective view of a bearing with a sensor according to this embodiment. FIG. 2 is an exploded perspective view of the bearing with a sensor of the present embodiment. FIG. 3 is a partial cross-sectional view of the bearing with a sensor of the present embodiment. FIG. 4 is a partial cross-sectional view of the bearing with a sensor of the present embodiment. FIG. 5 is an explanatory diagram for explaining the relationship between the voltage of the electromotive force and time in the bearing with a sensor of the present embodiment. FIG. 6 is a plan view of the sensor unit of the present embodiment. FIG. 7 is a perspective view of the cover of the present embodiment. FIG. 8 is a diagram showing a configuration of a circuit mounted on the bearing with a sensor of the present embodiment. FIG. 9 is a diagram showing a configuration of a power supply circuit for a bearing with a sensor according to the present embodiment. FIG. 10 is a diagram illustrating the impedance of the generator of the bearing with a sensor and the step-up chopper circuit of the present embodiment. FIG. 11 is a diagram showing an example of the output voltage of the generator of the bearing with a sensor of this embodiment. FIG. 12 is a diagram showing an example of the output voltage of the rectifier circuit of the bearing with a sensor of this embodiment. FIG. 13 is a diagram showing an example of an operation sequence of the circuit of the bearing with a sensor of this embodiment.

An embodiment (embodiment) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. In addition, the components described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the components described below can be combined as appropriate.

FIG. 1 is a perspective view of a bearing with a sensor according to this embodiment. FIG. 2 is an exploded perspective view of the bearing with a sensor of the present embodiment. FIG. 3 is a partial cross-sectional view of the bearing with a sensor of the present embodiment. FIG. 4 is a partial cross-sectional view of the bearing with a sensor of the present embodiment. As shown in FIG. 2, the bearing 1 with a sensor has a sensor unit 5, a tone ring 30, and a bearing body 20.

As shown in FIGS. 3 and 4, the bearing body 20 is a rolling bearing having an outer ring 21, an inner ring 22, and a rolling element 23. Hereinafter, the inner ring 22 will be described as a rotating ring, but as long as the outer ring 21 and the inner ring 22 rotate relative to each other, either the outer ring 21 or the inner ring 22 may rotate.

The cover 10 has an annular top plate 12 and a cylindrical side plate 11 connected around the top plate 12. The cover 10 is made of a soft magnetic material such as silicon steel plate, carbon steel (JIS standard SS400 or S45C), martensitic stainless steel (JIS standard SUS420) or ferritic stainless steel (JIS standard SUS430). ..

As shown in FIG. 2, in the sensor unit 5, a plurality of power generation units 3 and a sensor unit 40 are attached to facing surfaces of the top plate 12 on the bearing body 20 side. The sensor unit 40 has a power supply board 41 and a sensor board 42.

For example, as shown in FIGS. 1 and 2, each power generation unit 3 is fixed to the top plate 12 by fastening a bolt 19 made of a non-magnetic material such as brass to a female screw hole formed in the top plate 12. .. Similarly, the power supply board 41 and the sensor board 42 are fixed to the top plate 12 by fastening bolts 47 made of a non-magnetic material such as brass to the female screw holes made in the top plate 12. As shown in FIG. 1, the bolt 19 and the bolt 47 have a length that does not protrude from the top plate 12 in a state of being attached to the cover 10.

The tone ring 30 is provided with a convex portion 31 protruding toward the outer diameter side and a concave portion 32 recessed toward the inner diameter side of the convex portion 31 alternately in the circumferential direction. The tone ring 30 has a cylindrical protrusion 33 protruding toward the bearing body 20 on the inner peripheral side.

The tone ring 30 is made of a soft magnetic material such as silicon steel plate, carbon steel (JIS standard SS400 or S45C), martensitic stainless steel (JIS standard SUS420) or ferritic stainless steel (JIS standard SUS430). To.

Each power generation unit 3 has a permanent magnet 13, a yoke 14, and a coil 15. The permanent magnet 13 is fixed so as to be in contact with the top plate 12. The yoke 14 is fixed so as to be in contact with the magnet. The yoke 14 is made of a material having soft magnetism such as a silicon steel plate. It is desirable that the yoke 14 is made of a material having a magnetic permeability equal to or higher than that of the material of the cover 10 so that the amount of magnetic flux inside the yoke 14 increases.

The coil 15 is a so-called magnet wire in which a conducting wire winds around a yoke 14. It is desirable to wind as many conductors with as small a wire diameter as possible so that the amount of power generation increases. The coils 15 of the adjacent power generation units 3 are connected in series, and the wiring drawn from the coils 15 of the plurality of power generation units 3 connected in series is connected to the power supply board 41.

As shown in FIG. 3, one end of the side plate 11 is fitted and fixed in the groove 21A provided on the outer periphery of the outer ring 21. The tubular protrusion 33 is fitted and fixed in the groove 22A provided on the inner circumference of the inner ring 22. As a result, as shown in FIGS. 3 and 4, the inner peripheral end surface of the yoke 14 and the inner peripheral end surface of the top plate 12 are arranged at positions facing the convex portion 31 or the concave portion 32 of the tone ring 30.

FIG. 5 is an explanatory diagram for explaining the relationship between the voltage of the electromotive force and time in the bearing with a sensor of the present embodiment. Here, the horizontal axis of FIG. 5 is time, and the vertical axis is the voltage of the electromotive force. The outer ring 21 is fixed, and the rotation of the inner ring 22 causes the tone ring 30 to rotate together with the inner ring 22, and the tone ring 30 and each power generation unit 3 rotate relatively. The air gap from the inner peripheral end surface of the yoke 14 to the outer peripheral end surface 31IF of the convex portion 31 shown in FIG. 3 and the air gap from the inner peripheral end surface of the yoke 14 to the outer peripheral end surface 32IF of the concave portion 32 shown in FIG. , Alternate.

In this way, the distance between the yoke 14 of each power generation unit 3 and the outer circumference of the tone ring 30 is periodically changed by the convex portion 31 and the concave portion 32 on the outer circumference of the tone ring 30. As a result, the magnetic flux Mf generated in each power generation unit 3 changes. When the yoke 14 provided with the permanent magnet 13 and the tone ring 30 are close to each other, the magnetic flux passing through the permanent magnet 13, the yoke 14 and the tone ring 30 is large, and the yoke 14 and the tone ring 30 are separated from each other. If so, the magnetic flux passing through the permanent magnet 13, the yoke 14, and the tone ring 30 becomes smaller. In response to the change in the density of the magnetic flux Mf, a voltage change is generated in the coil 15 in which the magnet wire is wound around the yoke 14.

That is, when the yoke 14 and the outer peripheral end surface 31IF of the convex portion 31 are closest to each other, the magnetic flux Mf shown in FIG. 3 becomes large, and the electromotive force voltage V1 shown in FIG. 5 is supplied to the power supply board 41. When the yoke 14 and the outer peripheral end surface 32IF of the recess 32 are farthest from each other, the magnetic flux Mf shown in FIG. 4 becomes small, and the electromotive force voltage V2 shown in FIG. 5 is supplied to the power supply board 41.

FIG. 6 is a plan view of the sensor unit of the present embodiment. As shown in FIG. 6, the power supply unit 43 is mounted on the power supply board 41. The power supply unit 43 includes, for example, a rectifier circuit, a smoothing circuit, a protection circuit, and a power supply circuit. The power supply unit 43 converts the single-phase AC power supplied from the power generation unit 3 into a DC voltage and supplies it to the sensor board 42.

A sensor 44, a communication circuit 45, and an antenna 46 are mounted on the sensor board 42. The DC power output from the power supply unit 43 is at least supplied to the sensor 44 and the communication circuit 45.

The sensor 44 includes a temperature sensor that detects the ambient temperature of the bearing body 20, a vibration sensor that detects the vibration of the bearing body 20, a humidity sensor that detects the ambient humidity of the bearing body 20, and oxidative deterioration of the lubricating oil of the bearing body 20. Of various detection units such as a gas sensor that detects gaseous hydrocarbons, hydrogen sulfide, ammonia, etc., an ultrasonic sensor that detects frictional noise generated in the bearing body 20, and a rotation sensor that detects the rotation of the bearing body 20. It is provided with one or more detection units.

The communication circuit 45 is a device including a CPU (Central Processing Unit) and a wireless transmission / reception circuit. The device includes a microcomputer. The detection information detected by the sensor 44 is processed by the communication circuit 45, transmitted by wireless communication of the electromagnetic wave WV shown in FIG. 1 via the antenna 46, and received by, for example, the communication unit 51 of the host device 50. The detection information received by the communication unit 51 is processed by the computer 52. In the embodiment, the communication circuit 45 is a wireless communication circuit, but it may be a wired communication circuit.

FIG. 7 is a perspective view of the cover of the present embodiment. As shown in FIG. 7, the cover 10 is provided with a through hole 12H. As shown in FIG. 1, the through hole 12H is sealed with a non-magnetic lid 17 made of a non-magnetic material such as resin.

Since the cover 10 has soft magnetism, it has a function of shielding the electromagnetic wave WV from the antenna 46. Therefore, as shown in FIG. 6, the antenna 46 is arranged so as to overlap the non-magnetic lid 17 in the plan view of the bearing body 20 in the direction of the rotation axis Zr.

FIG. 8 is a diagram showing a configuration of a circuit mounted on the bearing with a sensor of the present embodiment. The circuit 200 includes a generator 201, a power supply unit 43, a sensor 44, a communication circuit 45, and an antenna 46. The power supply unit 43 includes a rectifier circuit 202, a smoothing circuit 203, a protection circuit 204, and a power supply circuit 205.

The generator 201 is composed of a plurality of power generation units 3 shown in FIGS. 2 to 4 and a tone ring 30. The generator 201 generates single-phase AC power and outputs it to the rectifier circuit 202. The rectifier circuit 202 full-wave rectifies the single-phase AC power generated by the generator 201 and outputs it to the smoothing circuit 203. The rectifier circuit 202 is exemplified by a diode bridge, but the present disclosure is not limited to this.

The smoothing circuit 203 smoothes the voltage rectified by the rectifier circuit 202 and outputs the voltage to the protection circuit 204. The smoothing circuit 203 is exemplified by a capacitor, but the present disclosure is not limited to this. The protection circuit 204 suppresses the DC voltage smoothed by the smoothing circuit 203 so as not to exceed a preset voltage, and outputs the voltage to the input terminal 205a of the power supply circuit 205. The protection circuit 204 is exemplified by a breakdown diode, but the present disclosure is not limited to this.

The power supply circuit 205 converts the DC voltage supplied to the input terminal 205a and outputs the DC voltage from the output terminal 205c on the high potential side and the output terminal 205d on the low potential side. In an embodiment, the power supply circuit 205 is a DC-DC converter, but the present disclosure is not limited thereto. The power supply circuit 205 may be an AC-DC converter that converts a single-phase AC voltage generated by the generator 201 into a DC voltage. The low potential is exemplified by the ground potential, but the present disclosure is not limited to this. A sensor 44 and a communication circuit 45 connected in parallel are connected to the output terminals 205c and 205d as loads.

The sensor 44 uses the DC power supplied from the power supply circuit 205 to sense various physical quantities or chemical quantities. The communication circuit 45 uses the DC power supplied from the power supply circuit 205 to wirelessly transmit the data sensed by the sensor 44 to the communication unit 51 (shown in FIG. 1) via the antenna 46.

FIG. 9 is a diagram showing a configuration of a power supply circuit for a bearing with a sensor according to the present embodiment. The power supply circuit 205 includes a power supply IC (Integrated Circuits) 210. The power supply IC 210 is exemplified by Texas Instruments bq25570, but the present disclosure is not limited to this.

The power supply IC 210 includes N-channel MOS type transistors Q1 and Q5 and P-channel MOS type transistors Q2, Q3 and Q4. Further, the power supply IC 210 compares the boost voltage threshold with the boost control unit 211, the maximum power point tracking control unit 212, the cold start control unit 213, the step-down control unit 214, and the nanopower control unit 215. A part 216 and the like.

The power supply circuit 205 includes a boost chopper circuit 221. The boost chopper circuit 221 is composed of a coil L1 outside the power supply IC 210, capacitors CSTOR and CBYP, transistors Q1 and Q2 inside the power supply IC 210, and a boost control unit 211.

The source of the transistor Q1 is grounded via the terminal VSS. A gate signal is supplied from the boost control unit 211 to the gate of the transistor Q1. The drain of the transistor Q1 is connected to the terminal LBOOST. One end of the coil L1 is connected to the terminal LBOOST. The other end of the coil L1 is connected to the input terminal 205a. Further, a capacitor CIN for smoothing the input voltage is connected between the input terminal 205a and the ground potential.

The drain of the transistor Q2 is connected to the terminal LBOOST. A gate signal is supplied to the gate of the transistor Q2 from the boost control unit 211. The source of the transistor Q2 is connected to the terminal VSTOR. Capacitors CSTOR and CBYP connected in parallel are connected between the terminal VSTOR and the ground potential.

The boost control unit 211 controls the transistor Q1 to be on and the transistor Q2 to be turned off at a certain timing. As a result, energy is stored in the coil L1. The boost control unit 211 controls the transistor Q1 to be off and the transistor Q2 to be on at the next one timing. As a result, the energy stored in the coil L1 is supplied to the capacitors CSTOR and CBYP. As a result, the boost chopper circuit 221 boosts the DC voltage supplied to the input terminal 205a. The voltage of the capacitors CSTOR and CBYP, that is, the voltage of the terminal VSTOR is the boost voltage (output voltage) of the boost chopper circuit 221.

The boost chopper circuit 221 corresponds to the boost circuit of the present invention. In the embodiment, the booster circuit is a booster chopper circuit 221, but the present disclosure is not limited to this.

The maximum power point tracking control unit 212 controls the boost control unit 211 to control the tracking of the maximum power point of the generator 201. The maximum power point tracking control unit 212 is set to operate based on the voltage supplied to the terminal VOC_SAMP.

FIG. 10 is a diagram illustrating the impedance of the generator of the bearing with a sensor and the step-up chopper circuit of the present embodiment. The generator 201 generates an open circuit voltage V _open . The generator 201 has an output impedance 201a. The step-up chopper circuit 221 has an input impedance 221a.

As a result of experiments, the present inventor has found that when the output impedance 201a of the generator 201 and the input impedance 221a of the boost chopper circuit 221 are the same, electric power can be suitably obtained from the generator 201. When the closed circuit voltage when the boost chopper circuit 221 is connected to the generator 201 is set to 50% of the open circuit voltage V _open when the boost chopper circuit 221 is not connected to the generator 201, the generator is generally used. It is known that the maximum power can be obtained from 201.

Therefore, in the embodiment, in the maximum power point tracking control unit 212, the closed circuit voltage, which is the generated voltage when the boost chopper circuit 221 is operating, is the generated voltage when the boost chopper circuit 221 is not operating. The boost chopper circuit 221 is controlled so as to have a voltage obtained by multiplying the open circuit voltage V _open and the ratio set by the voltage supplied to the terminal VOC_SAMP. The boost control unit 211 controls the input impedance 221a of the boost chopper circuit 221 by controlling the on time and the off time of the transistors Q1 and Q2. As a result, the power supply circuit 205 can suitably obtain electric power from the generator 201.

In the embodiment, the terminal _{VOC_SAMP} is supplied with a voltage obtained by dividing the input voltage supplied to the input terminal 205a by the resistance R _{OC 2} and the resistance R OC 1. By changing the resistance values of the resistors R _OC2 and R OC ₁ , the ratio to be multiplied by the open circuit voltage V _open can be changed.

The maximum power point tracking control unit 212 stops the boost chopper circuit 221 at regular time intervals, for example, every 16 seconds. At this time, the voltage obtained by dividing the open circuit voltage _Vopen of the generator 201 by the resistance R _OC2 and the resistance R _OC1 is supplied to the terminal VOC_SAMP. As described above, in the embodiment, the resistance values of the resistors _ROC2 and _ROC1 are set so that the input voltage of the boost chopper circuit 221 is 50% of the _open circuit voltage Vopen.

The maximum power point tracking control unit 212 samples the voltage supplied to the terminal VOC_SAMP. Then, the maximum power point tracking control unit 212 controls the boost chopper circuit 221 based on the voltage sampled from the terminal VOC_SAMP. A capacitor CREF is connected between the terminal VREF_SAMP and the ground potential. The maximum power point tracking control unit 212 outputs the voltage sampled from the terminal VOC_SAMP to the terminal VREF_SAMP.

The cold start control unit 213 controls a cold start that starts the operation of the power supply circuit 205 from a state in which electric power is not stored in each unit of the power supply circuit 205. The cold start control unit 213 is connected to the input terminal 205a via the terminal VIN_DC. The cold start control unit 213 causes the boost control unit 211 to start boost control when the input voltage supplied to the input terminal 205a reaches a predetermined voltage, for example, 100 mV.

The drain of the transistor Q3 is connected to the terminal VSTOR. A gate signal is supplied from the nanopower control unit 215 to the gate of the transistor Q3. The source of the transistor Q3 is connected to the terminal VBAT. A rechargeable battery BAT is connected between the terminal VBAT and the ground potential. In the embodiment, a tantalum capacitor is used as the battery BAT.

When the boost voltage of the boost chopper circuit 221 is higher than the voltage of the tantalum capacitor BAT, the tantalum capacitor BAT is charged via the parasitic diode of the transistor Q3.

The power supply circuit 205 includes a step-down chopper circuit 222. The step-down chopper circuit 222 includes a coil L2 and a capacitor COUT outside the power supply IC 210, transistors Q4 and Q5 inside the power supply IC 210, and a step-down control unit 214.

The source of the transistor Q4 is connected to the terminal VSTOR. A gate signal is supplied to the gate of the transistor Q4 from the step-down control unit 214. The drain of the transistor Q4 is connected to the terminal LBUCK. One end of the coil L2 is connected to the terminal LBUCK. The other end of the coil L2 is connected to the output terminal 205c. Further, a capacitor COUT is connected between the output terminal 205c and the ground potential. The other end of the coil L2 is fed back to the step-down control unit 214 via the terminal VOUT.

The drain of the transistor Q5 is connected to the terminal LBUCK. A gate signal is supplied to the gate of the transistor Q5 from the step-down control unit 214. The source of the transistor Q5 is grounded via the terminal VSS.

The step-down control unit 214 controls the transistor Q4 to be on and the transistor Q5 to be turned off at a certain timing. As a result, energy is stored in the coil L2. The step-down control unit 214 controls the transistor Q4 to be off and the transistor Q5 to be on at the next one timing. As a result, the energy stored in the coil L2 is supplied to the capacitor COUT. As a result, the step-down chopper circuit 222 steps down the step-up voltage of the step-up chopper circuit 221. The voltage of the capacitor COUT, that is, the voltage of the terminal VOUT is the step-down voltage (output voltage) of the step-down chopper circuit 222.

The step-down chopper circuit 222 corresponds to the step-down circuit of the present invention. In the embodiment, the step-down circuit is a step-down chopper circuit 222, but the present disclosure is not limited to this.

The nanopower control unit 215 outputs the bias voltage to the terminal VRDIV. The bias voltage output from the terminal VRDIV is divided by the resistance ROV2 and the resistance ROV1 and supplied to the terminal VBAT_OV. The bias voltage output from the terminal VRDIV is divided by the resistors ROK3 and ROK2 and the resistor ROK1 and supplied to the terminal OK_PROG. The bias voltage output from the terminal VRDIV is divided by the resistors ROK3 and the resistors ROK2 and ROK1 and supplied to the terminal OK_HYST. The bias voltage output from the terminal VRDIV is divided by the resistance ROUT2 and the resistance ROUT1 and supplied to the terminal VOUT_SET.

The nanopower control unit 215 is set to operate based on the voltages supplied to the terminals VBAT_OV, OK_PROG, OK_HYST and VOUT_SET.

The voltage supplied to the terminal VBAT_OV sets the overvoltage threshold of the terminal VBAT. The nanopower control unit 215 controls the transistor Q3 to be turned off when the voltage of the terminal VBAT exceeds the overvoltage threshold value. As a result, the nanopower control unit 215 can prevent the tantalum capacitor BAT from being damaged by the overvoltage.

The voltage supplied to the terminal OK_PROG sets the first boost voltage threshold when the voltage (boost voltage) of the terminal VSTOR is rising. The boosted voltage threshold value comparison unit 216 outputs a high-level signal to the terminal VBAT_OK when the voltage of the terminal VSTOR is rising and is equal to or higher than the first boosted voltage threshold value. Further, the boosted voltage threshold value comparison unit 216 outputs a low level signal to the terminal VBAT_OK when the voltage of the terminal VSTOR is rising and is smaller than the first boosted voltage threshold value.

The voltage supplied to the terminal OK_HYST sets a second boost voltage threshold when the voltage (boost voltage) of the terminal VSTOR is falling. The boosted voltage threshold value comparison unit 216 outputs a high-level signal to the terminal VBAT_OK when the voltage of the terminal VSTOR is falling and is equal to or higher than the second boosted voltage threshold value. Further, the boosted voltage threshold value comparison unit 216 outputs a low level signal to the terminal VBAT_OK when the voltage of the terminal VSTOR is decreasing and smaller than the second boosted voltage threshold value.

The first boosted voltage threshold value and the second boosted voltage threshold value may be the same or different.

The voltage supplied to the terminal VOUT_SET sets the voltage (step-down voltage) of the terminal VOUT. By changing the resistance values of the resistors R _OUT2 and R _OUT1 , the step-down voltage of the step-down chopper circuit 222 can be changed. The step-down control unit 214 controls the step-down chopper circuit 222 so that the step-down voltage of the step-down chopper circuit 222 matches the voltage supplied to the terminal VOUT_SET. Generally, the threshold value of the operating voltage of the sensor 44 and the communication circuit 45 is about 1.8V to 3.3V. Therefore, in the embodiment, the resistance values of the resistors R _OUT 2 and R _OUT 1 are set so that the step-down voltage of the step-down chopper circuit 222 is about 1.8 V to 3.3 V.

The nanopower control unit 215 controls the transistor Q3 to be turned on when the voltage of the generator 201 drops and the boost voltage of the boost chopper circuit 221 drops below the voltage of the tantalum capacitor BAT. As a result, the electric power stored in the tantalum capacitor BAT is supplied to the step-down chopper circuit 222, and the step-down chopper circuit 222 can continue to output the step-down voltage.

The voltage supplied to the terminal EN bar sets the operation or non-operation of the power supply IC 210. The power supply IC 210 operates when the voltage of the terminal EN bar is at a low level. The power supply IC 210 does not operate when the voltage of the terminal EN bar is at a high level. In the embodiment, the terminal EN bar is grounded. Therefore, the power supply IC 210 operates.

The voltage supplied to the terminal VOUT_EN sets the operation or non-operation of the step-down chopper circuit 222. The step-down chopper circuit 222 operates when the voltage of the terminal VOUT_EN is at a high level. Further, the step-down chopper circuit 222 does not operate when the voltage of the terminal VOUT_EN is low level.

In the embodiment, the terminal VOUT_EN is connected to the terminal VBAT_OK. Therefore, the step-down chopper circuit 222 operates when the voltage of the terminal VBAT_OK is at a high level. Further, the step-down chopper circuit 222 does not operate when the voltage of the terminal VBAT_OK is low level.

As described above, the voltage of the terminal VBAT_OK is when the boost voltage is rising and is equal to or higher than the first boost voltage threshold, or when the boost voltage is falling and is equal to or higher than the second boost voltage threshold. In some cases, it goes to a high level. Further, the voltage of the terminal VBAT_OK becomes low level when the boost voltage is rising and is smaller than the first boost voltage threshold, or when the boost voltage is falling and is smaller than the second boost voltage threshold. Become.

From the above, in the step-down chopper circuit 222, when the boost voltage is rising and is equal to or higher than the first boost voltage threshold, or when the boost voltage is falling and is equal to or higher than the second boost voltage threshold. Operate. Further, the step-down chopper circuit 222 does not operate when the boost voltage is rising and is smaller than the first boost voltage threshold, or when the boost voltage is falling and is smaller than the second boost voltage threshold.

A decoupling capacitor 225 is connected between the output line 223 on the high potential side of the power supply circuit 205 and the ground potential. The decoupling capacitor 225 is sometimes referred to as a bypass capacitor. The decoupling capacitor 225 passes the AC component in the step-down voltage and does not pass the DC component. As a result, only the DC component in the step-down voltage is supplied to the output terminal 205c on the high potential side. The decoupling capacitor 225 is a circuit element indispensable for stable operation of the load (in the embodiment, the sensor 44 and the communication circuit 45).

An N-channel MOS type transistor 226 is arranged between the terminal on the low potential side of the decoupling capacitor 225 and the output terminal 205d on the low potential side. The transistor 226 is not limited to the N-channel MOS type, and may be a P-channel MOS type.

The source of the transistor 226 is connected to the terminal on the low potential side of the decoupling capacitor 225. The drain of the transistor 226 is connected to the output terminal 205d on the low potential side via the output line 224 on the low potential side.

The gate of the transistor 226 is connected to the terminal VBAT_OK. Therefore, the transistor 226 is turned on when the voltage of the terminal VBAT_OK is at a high level. Further, the transistor 226 is turned off when the voltage of the terminal VBAT_OK is low level.

As described above, the voltage of the terminal VBAT_OK is when the boost voltage is rising and is equal to or higher than the first boost voltage threshold, or when the boost voltage is falling and is equal to or higher than the second boost voltage threshold. In some cases, it goes to a high level. Further, the voltage of the terminal VBAT_OK becomes low level when the boost voltage is rising and is smaller than the first boost voltage threshold, or when the boost voltage is falling and is smaller than the second boost voltage threshold. Become.

Therefore, the transistor 226 is turned on when the boost voltage is rising and is equal to or higher than the first boost voltage threshold, or when the boost voltage is falling and is equal to or higher than the second boost voltage threshold. ..

Further, the transistor 226 is turned off when the boost voltage is rising and is smaller than the first boost voltage threshold, or when the boost voltage is falling and is smaller than the second boost voltage threshold.

When the transistor 226 is on, the voltage of the decoupling capacitor 225 is supplied to the sensor 44 and the communication circuit 45 via the output terminals 205c and 205d. Further, when the transistor 226 is in the off state, the output line 224 on the low potential side is cut off, so that the voltage of the decoupling capacitor 225 is not supplied to the sensor 44 and the communication circuit 45.

When the rotation of the inner ring 22 is stable and the power generation of the generator 201 is stable, the output voltage of the generator 201 becomes a stable sine wave as shown in FIG. 5 above. In this case, since the input voltage of the power supply circuit 205 is stable, the boost chopper circuit 221 can output the boost voltage as set. Then, the step-down chopper circuit 222 can output the step-down voltage as set. Further, since the voltage of the terminal VBAT_OK becomes high level, the transistor 226 is turned on. Therefore, the voltage of the decoupling capacitor 225 as set is supplied to the sensor 44 and the communication circuit 45 via the output terminals 205c and 205d. As a result, the sensor 44 and the communication circuit 45 can operate normally.

FIG. 11 is a diagram showing an example of the output voltage of the generator of the bearing with a sensor of this embodiment. FIG. 12 is a diagram showing an example of the output voltage of the rectifier circuit of the bearing with a sensor of this embodiment. When the rotation of the inner ring 22 is unstable and the power generation of the generator 201 is unstable, the output voltage of the generator 201 becomes unstable as shown in FIG. Therefore, as shown in FIG. 12, the output voltage of the rectifier circuit 202 also becomes unstable. In this case, since the input voltage of the power supply circuit 205 is unstable, the boost chopper circuit 221 cannot output the boost voltage as set. Therefore, the step-down chopper circuit 222 cannot output the step-down voltage as set.

In this case, if the transistor 226 does not exist, the following situation may occur. The sensor 44 and the communication circuit 45 continue to operate using the electric power stored in the decoupling capacitor 225 even if the step-down chopper circuit 222 cannot output the step-down voltage as set. Then, the voltage of the decoupling capacitor 225 gradually decreases. Then, the sensor 44 and the communication circuit 45 may operate abnormally when the voltage of the decoupling capacitor 225 reaches the vicinity of the threshold value of the operating voltage of the sensor 44 and the communication circuit 45.

Further, in the bearing 1 with a sensor, since the output voltage of the generator 201 fluctuates according to the rotation speed of the inner ring 22, the supply start and the supply stop of the step-down voltage are frequently repeated. The sensor 44 and the communication circuit 45 operate by receiving power supplied from the decoupling capacitor 225, so that the voltage of the decoupling capacitor 225 gradually drops, and the power supply from the step-down chopper circuit 222 suddenly drops. By restarting, the voltage of the decoupling capacitor 225 suddenly fluctuates, and the voltage supplied to the sensor 44 and the communication circuit 45 suddenly fluctuates. As a result, there is an extremely high possibility that the sensor 44 and the communication circuit 45 will operate abnormally.

Since the input voltage is stable in the power supply circuit of a general device, the output voltage is also stable. Further, the load circuit of a general device consumes a large amount of power and immediately consumes the power stored in the decoupling capacitor, so that it is extremely unlikely that the load circuit will operate abnormally. On the other hand, in the bearing 1 with a sensor, the rotation speed of the inner ring 22 can be unstable, so that the generated voltage can be unstable, and eventually the output voltage can be unstable. Further, in the bearing 1 with a sensor, since the load circuit, that is, the sensor 44 and the communication circuit 45 consumes a small amount of power, they can operate with the power stored in the decoupling capacitor 225. Therefore, the above situation is a problem peculiar to the bearing 1 with a sensor.

However, in the power supply circuit 205 according to the embodiment, when the boost voltage is rising and is smaller than the first boost voltage threshold, or when the boost voltage is falling and is smaller than the second boost voltage threshold, , The voltage of the terminal VBAT_OK becomes low level. As a result, the transistor 226 is turned off. Therefore, the electric power stored in the decoupling capacitor 225 is not supplied to the sensor 44 and the communication circuit 45. Therefore, the sensor 44 and the communication circuit 45 cannot operate. As a result, the power supply circuit 205 can suppress the possibility that the sensor 44 and the communication circuit 45 operate abnormally.

Further, when the transistor 226 is turned off, the electric power stored in the decoupling capacitor 225 is preserved without being consumed by the sensor 44 and the communication circuit 45. Therefore, when the rotational speed of the bearing with the sensor is restored, the generated power of the generator 201 is restored, and the power supply circuit 205, the sensor 44, and the communication circuit 45 start the next operation, the charge amount to the decoupling capacitor 225 is charged. However, less is required. As a result, the power supply circuit 205 can accelerate the rise of the voltage of the decoupling capacitor 225, and can accelerate the start of operation of the sensor 44 and the communication circuit 45.

The setting of the capacity of the capacitor CSTOR and CBYP and the tantalum capacitor BAT will be described.

FIG. 13 is a diagram showing an example of an operation sequence of the circuit of the bearing with a sensor of this embodiment. The circuit 200 performs initial charging of the capacitors CSTOR and CBYP and the tantalum capacitor BAT in the period T0 after the start of operation. In the next period T1, the communication circuit 45 establishes communication with the communication unit 51. In the next period T2, the sensor 44 performs sensing. In the next period T3, the communication circuit 45 performs communication for transmitting sensing data to the communication unit 51. Similarly, in the next period T4, the sensor 44 performs sensing. In the next period T5, the communication circuit 45 performs communication for transmitting sensing data to the communication unit 51.

The capacities of the capacitors CSTOR and CBYP and the tantalum capacitor BAT are as follows. When the power generation voltage of the generator 201 drops after the initial charge of the capacitors CSTOR and CBYP and the tantalum capacitor BAT in the period T0, and the power supply from the boost chopper circuit 221 to the capacitors CSTOR and CBYP and the tantalum capacitor BAT is cut off. Is assumed. Even in this case, the sensor 44 and the communication circuit 45 can operate in the period from the period T1 to the period T3, that is, the voltage of the terminal VSTOR at the end of the period T3 exceeds the second boost voltage threshold. The capacities of the capacitors CSTOR and CBYP and the tantalum capacitor BAT are set so that only the electric power can be charged.

If the capacities of the capacitors CSTOR and CBYP and the tantalum capacitor BAT are smaller than the above capacities, when the fluctuation of the generated voltage of the generator 201 is repeated, the sensor 44 and the communication circuit 45 communicate the sensing data. It will not be possible to send to 51 at all.

On the other hand, if the capacities of the capacitors CSTOR and CBYP and the tantalum capacitor BAT are equal to or larger than the above capacities, the sensor 44 and the communication circuit 45 can be charged by one initial charge even if the generated voltage of the generator 201 repeatedly fluctuates. The sensing data can be transmitted to the communication unit 51 at least once. Therefore, even if the fluctuation of the generated voltage of the generator 201 is repeated, the circuit 200 repeats from the period T0 to the period T3, so that the sensor 44 and the communication circuit 45 can transmit the sensing data to the communication unit 51.

The specific capacities of the capacitors CSTOR and CBYP and the tantalum capacitor BAT are the generated voltage of the generator 201, the second boost voltage threshold, the capacity of the decoupling capacitor 225, the threshold of the operating voltage of the sensor 44 and the communication circuit 45, and the sensor. It is determined in consideration of the power consumption in the period from the period T1 to the period T3 of the 44 and the communication circuit 45, the loss of each part of the circuit 200, and the like.

Further, in the embodiment, the transistor 226 is arranged between the terminal on the low potential side of the decoupling capacitor 225 and the output terminal 205d on the low potential side, but the present disclosure is not limited to this. .. The transistor 226 may be arranged between the terminal on the high potential side of the decoupling capacitor 225 and the output terminal 205c on the high potential side.

However, if the transistor 226 is arranged between the terminal on the high potential side of the decoupling capacitor 225 and the output terminal 205c on the high potential side, the on-resistance of the transistor 226 causes the sensor 44 and the communication circuit 45 to be connected. The potential applied to the input terminal on the high potential side drops. On the other hand, when the transistor 226 is arranged between the terminal on the low potential side of the decoupling capacitor 225 and the output terminal 205d on the low potential side, it becomes the input terminal on the high potential side of the sensor 44 and the communication circuit 45. The applied potential does not drop. Therefore, it is preferable that the transistor 226 is arranged between the terminal on the low potential side of the decoupling capacitor 225 and the output terminal 205d on the low potential side.

Further, in the embodiment, the voltage of the terminal VBAT_OK is supplied to the gate of the transistor 226, but the present disclosure is not limited to this. When the voltage of the terminal VBAT_OK becomes high level, the boost voltage is rising and is equal to or higher than the first boost voltage threshold, or the boost voltage is falling and is equal to or higher than the second boost voltage threshold. This is the case. When the boost voltage is rising and is equal to or higher than the first boost voltage threshold, or when the boost voltage is falling and is equal to or higher than the second boost voltage threshold, the step-down chopper circuit 222 is as set. This is the case when the step-down voltage can be output.

Further, when the voltage of the terminal VBAT_OK becomes low level, the boost voltage is rising and is smaller than the first boost voltage threshold, or the boost voltage is falling and the second boost voltage threshold is low. If it is smaller. When the boost voltage is rising and is smaller than the first boost voltage threshold, or when the boost voltage is falling and is smaller than the second boost voltage threshold, the step-down chopper circuit 222 steps down as set. This is the case when the voltage cannot be output.

Therefore, the power supply circuit 205 has a step-down voltage threshold comparison unit that compares the step-down voltage of the step-down chopper circuit 222 with the set step-down voltage threshold value inside the power supply IC 210 (for example, the nanopower control unit 215 according to the embodiment). Alternatively, it may be prepared externally. Then, the step-down voltage threshold comparison unit outputs a signal that becomes high level when the step-down voltage of the step-down chopper circuit 222 is equal to or higher than the step-down voltage threshold value, and becomes low level when the step-down voltage of the step-down chopper circuit 222 is smaller than the step-down voltage threshold value. , May be output to the gate of transistor 226. The step-down voltage threshold value may be divided into a first step-down voltage threshold value when the step-down voltage is rising and a second step-down voltage threshold value when the step-down voltage is falling.

1 Bearing with sensor 5 Sensor unit 10 Cover 11 Side plate 12 Top plate 14 Yoke 15 Coil 20 Bearing body 21 Outer ring 22 Inner ring 23 Rolling element 30 Tone ring 41 Power supply board 42 Sensor board 43 Power supply unit 44 Sensor 45 Communication circuit 46 Antenna 201 Generator 202 Rectification circuit 203 Smoothing circuit 204 Protection circuit 205 Power supply circuit 211 Boost control unit 212 Maximum power point tracking control unit 213 Cold start control unit 214 Step-down control unit 215 Nano power control unit 216 Boost voltage threshold comparison unit 221 Boost-up voltage threshold comparison unit 221 Step-up chopper circuit 222 Step-down chopper circuit 225 decoupling capacitor 226 transistor

Claims (4)

A power supply circuit that supplies power to the load
A power supply IC that controls the output voltage applied to the load, and
A decoupling capacitor connected between the output terminal on the high potential side of the output voltage to which the load is connected and the reference potential,
A switch circuit provided between the output terminal on the low potential side of the output voltage to which the load is connected and the terminal on the low potential side of the decoupling capacitor,
Equipped with
The power supply IC is
A first voltage threshold and a second voltage threshold having a potential higher than the reference potential and a potential lower than the first voltage threshold are preset, and the output voltage and the first voltage threshold are set. A voltage threshold comparison unit for controlling the switch circuit by comparing with the second voltage threshold is provided.
The voltage threshold value comparison unit is
When the output voltage is rising and is equal to or higher than the first voltage threshold, or when the output voltage is falling and is equal to or higher than the second voltage threshold, the switch circuit is controlled to be in the ON state. The signal is output to the switch circuit,
When the output voltage is rising and smaller than the first voltage threshold value, or when the output voltage is falling and smaller than the second voltage threshold value, the switch circuit is controlled to be in the off state. Output the signal to the switch circuit,
Power circuit. The switch circuit is an N-channel MOS type transistor.
In the transistor, the source-drain path is inserted between the output terminal on the low potential side and the terminal on the low potential side of the decoupling capacitor.
The power supply circuit according to claim 1 . The power supply IC outputs the signal to the gate of the transistor.
The power supply circuit according to claim 2 . A power supply circuit that supplies power to the load
A decoupling capacitor electrically connected between the output terminals to which the load is connected, and
A switch circuit that cuts off the electrical connection between the output terminal and the decoupling capacitor,
Equipped with
When the voltage between the output terminals is rising and is equal to or higher than the first voltage threshold, or when the voltage between the output terminals is falling and the potential is lower than the first voltage threshold, the second voltage When the voltage is equal to or higher than the threshold value, the switch circuit is controlled to be in the ON state.
The switch circuit when the voltage between the output terminals is rising and smaller than the first voltage threshold value, or when the voltage between the output terminals is falling and smaller than the second voltage threshold value. To control the off state,
Power circuit.

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