JP2017169410A - Power reception device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of a circuit failure in a power reception device, when performing wireless power supply between a ground device and a moving body, caused by excessive power supply when approaching closer than expected, because of a coupling coefficient change due to a distance fluctuation therebetween, in wireless power supply in which, in order to improve power supply efficiency, a power reception device antenna is resonated to increase an antenna end voltage (or current).SOLUTION: When a power wave reception level rises, an inductor is connected in parallel with a capacitor which is disposed in series with the antenna to form a parallel resonant circuit. Thus, the circuit in the power reception device is protected by increasing overall antenna impedance to suppress reception efficiency.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power receiving device of a non-contact power feeding system using magnetic coupling.

  In recent years, the demand for non-contact power supply (wireless power supply) systems is increasing in the fields of electric vehicles and consumer electronic devices. In this system, by installing an electronic device including a power receiving device so as to face the power feeding device, it is possible to supply electric power without connecting both with a cable.

  Patent Documents 1 and 2 describe apparatuses that perform such wireless power feeding.

  Patent Document 1 states that “the non-contact charging device 3 includes a secondary coil 13 provided corresponding to the primary coil 7 of the charger 2 and a resonance capacitor 14 connected in parallel with the secondary coil 13. The circuit 15 includes a rectifier circuit 16 disposed between the resonant circuit 15 and the secondary battery 11. Between the rectifier circuit 16 and the secondary battery 11, a charge / discharge control circuit 19 and a charging current are provided. The charging power monitoring circuits 20 and 21 for monitoring the voltage value and / or current value of the resonance circuit 15 are provided.The resonance circuit 15 switches the connection state of the resonance capacitor 14 and / or the secondary coil 13 to change the impedance of the resonance circuit 15. A changeover switch 25 is provided for switching between large and small.When the charge power monitoring circuit 20 or 21 detects that the voltage value and / or current value of the secondary battery 11 has reached a predetermined value, The electrical control circuit 19 switches the changeover switch 25 to change the resonance circuit 15 from the first power receiving state in which the power receiving state is optimal to the second power receiving state in which the received power is significantly reduced. ing.

  Patent Document 2 states that “a power receiving device according to an embodiment of the present disclosure includes a power receiving unit that receives power fed in a non-contact manner from a power feeding device, and protection that varies a received voltage of power received by the power receiving unit. The circuit unit and a control unit that controls the operation state of the protection circuit unit to a plurality of states based on a plurality of threshold values ”are described.

JP2013-212043 International Publication Number WO 2015/115285

  Since wireless power feeding is used, for example, between a power feeding device provided on the ground and a power receiving device provided on a moving body, the coupling coefficient changes due to a change in the distance between them or a positional deviation between the two. Here, on the power receiving device side, the resonance of the power receiving antenna is set sharply (Q is increased) to increase the antenna end voltage (or current) in order to increase the power feeding efficiency, so the distance from the power feeding device is larger than expected. When approaching, excessive power supply will be received. Although the fluctuation of the power supply varies depending on the device specifications, there is a device having a change width of 100 times or more when it is large, and there is a problem that a device in the power receiving device breaks down.

  As a means for solving the above problem, when the power receiving device receives more power than necessary, a method is used in which the reception sensitivity of the antenna in the power receiving device is lowered to prevent a failure of the circuit in the power receiving device.

  In Patent Document 1, when the secondary battery in the receiving device is fully charged, the capacitor used for antenna resonance is opened to prevent overcharging, and the impedance of the power receiving antenna is increased by using a non-resonant antenna. Thus, a configuration for reducing the reception efficiency is shown. However, with this method, the impedance of the power receiving antenna cannot be increased beyond the reactance of the antenna coil, and the reception efficiency cannot be reduced below that of a single loop antenna (non-resonant antenna). In other words, the protection performance is not limited by the dimensions of the loop antenna, and there is a problem that it is desired to obtain sufficient protection performance against high power.

  Patent Document 2 discloses a configuration in which a capacitor is connected to both ends of a series resonant antenna to reduce the antenna end voltage when the antenna end voltage in the power receiving apparatus increases and the rectifier circuit output voltage exceeds a threshold value. ing. However, this method has a problem that a capacitor for series resonance or the like may break down because the current flowing through the power receiving antenna increases conversely.

  An object of the present invention is to provide a power receiving device that protects a circuit of a power receiving device even when the dynamic range of power reaching the power receiving device from the power feeding device is wide.

  In order to solve the above problem, one of the representative power receiving devices of the present invention includes a power receiving antenna for receiving a power wave output from the power feeding device, and a power receiving device that uses the power received by being connected to the power receiving antenna. In a power receiving device comprising a power supply unit, a determination unit that monitors the operation of the power reception unit and detects an excessive input of power, and a protection circuit that is connected in series to the power receiving antenna and increases the impedance at both ends according to the output of the determination unit And the reception efficiency of the power receiving antenna is lowered by increasing the impedance at both ends of the protection circuit when the determination unit detects an excessive input of power.

  According to the present invention, the switching unit is short-circuited at the time of excessive input, the antenna resonance capacitor and the resonance inductor are connected in parallel, and they are parallel-resonated at the same frequency as the power wave, so that both ends of the antenna resonance capacitor are connected. By increasing the impedance, the reception efficiency can be greatly reduced. Thereby, even when the dynamic range of the electric power reaching the power receiving device from the power feeding device is wide, the circuit of the power receiving device can be protected.

1 is an overall schematic diagram of a system according to a first embodiment. 1 is a block diagram illustrating a circuit configuration of Example 1. FIG. It is a figure which shows the case where the antenna circuit of FIG. 2 is used as a parallel resonant antenna. FIG. 3 is a diagram in which the antenna resonance capacitor and the protection circuit resonance inductor of FIG. 2 are interchanged. It is a figure which shows the example using a high impedance circuit. It is a figure which shows the example provided with two or more protection circuits. It is a figure which shows the example provided with two or more inductors for protection circuit resonance. FIG. 2 is a diagram in which a variable resistor or a MOSFET is used for a switching unit in the configuration of FIG. FIG. 5 is a diagram in which a variable resistor or a MOSFET is used for a switching unit in the configuration of FIG.

  Hereinafter, examples will be described with reference to the drawings.

  An overall outline of this embodiment is shown in FIG. The power receiving device (220) of the present embodiment uses the power receiving antenna (221) for receiving the power wave (200) output by the opposing power feeding device (210) and the power received by the power receiving antenna (221). The power receiving unit (122), the determination unit (123) that detects the excessive input of the power wave (200) by monitoring the operation of the power receiving unit (122), and the determination unit (123) detects and outputs the excessive input A protection circuit (231) that increases the impedance by the detection signal is provided, and the protection circuit (231) is mounted in series with the power receiving antenna (221).

  A detailed embodiment of this example is shown in FIG. The power feeding device (210) includes a power source (211) that is a power wave generating source, and a power feeding antenna (212) that is connected to the power source (211) and outputs a power wave (200) to the outside.

  The power receiving device (220) connects the antenna resonance capacitor (228) in series with the power receiving antenna (221) to form an antenna circuit (230). The constant of the antenna resonance capacitor (228) is set so that the resonance frequency of the antenna circuit (230) matches the frequency of the power wave (200). A rectifier circuit (223) is connected to both ends of the antenna circuit (230) to convert an AC voltage induced in the antenna into a DC voltage. The output of the rectifier circuit (223) is connected to a load circuit (224) having an arbitrary function such as signal output to the outside or charging of a battery provided inside.

  Also, a determination circuit (225) that monitors the operation of the rectifier circuit (223) to detect an excessive input of the power wave, and a switching unit that is short-circuited by a detection signal that the determination circuit (225) detects and outputs an excessive input ( 226). That is, the switching unit (226) reduces the impedance at both ends when the determination circuit (225) receives a detection signal output by detecting an excessive input.

  In addition, it includes a capacitor for resonant antenna (228) and an inductor for resonant circuit (227) that resonates at the frequency of the power wave (200), and the protective circuit resonant inductor (227) and switching unit (226) are connected in series. Are connected in parallel to the antenna resonance capacitor (228).

  According to this configuration, when the level of the power wave (200) received by the power receiving device (220) is in a normal range, the switching unit (226) is opened and the antenna circuit (230) is connected to the power wave (200). Resonance with frequency improves reception efficiency.

  On the other hand, when the input is excessive, the judgment circuit (225) shorts the switching unit (226), thereby connecting the antenna resonance capacitor (228) and the protection circuit resonance inductor (227) in parallel to form the protection circuit (231). To do. Since the protection circuit (231) resonates in parallel at the frequency of the power wave (200), the impedance at both ends is significantly increased. Thereby, the reception efficiency of the power wave (200) can be lowered and the circuit can be protected.

  In FIG. 2, the number of antenna resonance capacitors (228) and the number of protection circuit resonance inductors (227) is shown one by one. Here, even when there are a plurality of antenna resonance capacitors (228), the same effect can be obtained by forming the protection circuit (231) for one or more of the capacitors.

  Here, in the above description, the resonance frequency of the antenna circuit (230) and the protection circuit (231) is made to match the frequency of the power wave (200), but the same effect can be obtained even if it does not completely match. In addition, there is an advantage that variation in impedance of the protection circuit due to variation in the constants of components can be reduced.

  In addition to the operation of the rectifier circuit (223), the determination circuit (225) monitors the DC voltage value output by the rectifier circuit (223) and the operation of the load circuit (224) (part temperature and battery charge). Amount) etc.

  In the above description, the switching unit (226) has been described as a switch that indicates two states of short circuit and open circuit. However, as shown in FIGS. 8 (a) and 8 (b), a variable resistor, MOSFET, etc. It may be replaced with. 8 makes it possible to continuously adjust the resistance value of the variable resistor (826) or the MOSFET (829) instead of discretely, so that the reception efficiency of the power wave (200) is continuously increased. Thus, the output voltage of the rectifier circuit (223) can be stabilized near the limit value of the determination circuit (225). In addition, since a parasitic diode is attached to the MOSFET, there is a problem that the impedance in one direction is lowered even when no detection signal is input. However, as shown in FIG. The above problems can be solved by connecting in series or by using a circuit configuration in which a current is allowed to flow through the MOSFET only in one direction using a diode bridge as shown in FIG. 8 (d).

  Further, as shown in FIG. 3, a parallel resonant antenna circuit (330) may be formed by connecting an antenna parallel resonant capacitor (322) in parallel with the antenna circuit (230). During normal power reception, the parallel resonant antenna circuit (330) resonates to improve the reception efficiency, and when it is excessively input, a protection circuit (231) is formed to lower the reception efficiency. Furthermore, since the parallel resonant antenna circuit (330) has a high output impedance, power can be transmitted with high efficiency when the input impedances of the rectifier circuit (223) and the load circuit (224) are high.

  FIG. 4 shows an example in which the antenna resonance capacitor (228) and the protection circuit resonance inductor (227) are replaced with those of the first embodiment. The protection circuit antenna inductor (428) is mounted instead of the antenna resonance capacitor (228), and the protection circuit resonance capacitor (427) is mounted instead of the protection circuit resonance inductor (227). Set a constant to resonate.

  According to this configuration, the same protective effect as that of the first embodiment can be obtained at the time of excessive input. In the configuration of FIG. 4, the antenna circuit (230) is a non-resonant antenna during normal power reception, but an antenna resonance capacitor (228) may be added to form a resonant antenna as in the first embodiment.

  Further, instead of the protection circuit antenna inductor (428), the protection circuit (231) can be formed by using a part of the power receiving antenna (221) or an inductance such as a wiring pattern.

  In the above description, the switching unit (226) is described as a switch that indicates two states of short circuit and open circuit. However, as shown in FIGS. It may be replaced with. By configuring as shown in FIG. 9, the resistance value of the variable resistor (826) or the MOSFET (829) can be continuously adjusted instead of discretely, so that the reception efficiency of the power wave (200) is continuously increased. Thus, the output voltage of the rectifier circuit (223) can be stabilized near the limit value of the determination circuit (225). In addition, since a parasitic diode is attached to the MOSFET, there is a problem that the impedance in one direction is lowered even when no detection signal is input. However, as shown in FIG. The above problem can be solved by connecting in series, or by using a circuit configuration in which a current is allowed to flow through the MOSFET only in one direction using a diode bridge as shown in FIG. 9 (d).

  An example of switching the wiring path of the antenna circuit (230) at the time of excessive input is shown in FIG. The power receiving device (220) includes a power receiving antenna (221) for receiving the power wave (200) output from the power feeding device (210), and includes an antenna resonance capacitor (228) and a switching unit (226) in series with the power receiving antenna. Are connected to form an antenna circuit (230). Further, the rectifier circuit (223) is connected to both ends of the antenna circuit (230) to convert the induced AC voltage into a DC voltage, and the load circuit (224) is connected to the output of the rectifier circuit (223). In addition, it includes a determination circuit (225) that monitors the operation of the rectifier circuit (223) and detects an excessive input of the power wave, and the determination circuit (225) detects the excessive input and outputs the switching unit (226 ) Is released. Further, a high impedance circuit (532) set to an arbitrary impedance is connected in parallel with the switching unit (226).

  According to this configuration, since the switching unit (226) is short-circuited during normal power reception, the antenna circuit (230) resonates to improve reception efficiency. On the other hand, when the input is excessive, the switching unit (226) is opened and the high impedance circuit (532) is connected in series with the antenna circuit (230), so that the reception efficiency of the power wave (200) is lowered to protect the circuit. I can do it.

  Note that the number of antenna resonance capacitors (228) may be two or more, or may be a non-resonant antenna without being mounted.

  Here, in the above description, the resonance frequency of the antenna circuit (230) and the protection circuit (231) is made to match the frequency of the power wave (200), but the same effect can be obtained even if it does not completely match. In addition, there is an advantage that variation in impedance of the protection circuit due to variation in the constants of components can be reduced.

  In addition to the operation of the rectifier circuit (223), the determination circuit (225) monitors the DC voltage value output by the rectifier circuit (223) and the operation of the load circuit (224) (part temperature and battery charge). Amount) etc.

  FIG. 6 shows an example in which a second protection circuit (631) is provided with respect to the first embodiment. A second antenna resonance capacitor (628) connected in series with the power receiving antenna (221), a second switching unit (626) which is short-circuited by a signal output by the determination circuit (225) detecting an excessive input, A second protection circuit resonance inductor (627) that resonates at the frequency of the second antenna resonance capacitor (628) and the power wave (200), and the second protection circuit resonance inductor (627) and the second switching The part (626) connected in series is connected in parallel with the second antenna resonance capacitor (628). Furthermore, the judgment circuit (225) has two judgment thresholds for excessive input, and when the first threshold is exceeded, the (first) switching unit (226) is short-circuited and exceeds the second threshold. To short-circuit the second switching unit (626). Further, the second threshold is set higher than the first threshold.

  According to the present embodiment, the increase in the number of protection circuits (231) and (631) increases the amount of increase in impedance of the antenna circuit (230), thereby further reducing the reception efficiency. In addition, by operating the protection circuit in stages, the reception efficiency can be reduced in stages and the rectified voltage can be stabilized. Note that the number of protection circuits may be three or more. As the number of protection circuits increases, the reception efficiency can be suppressed in multiple stages.

  FIG. 7 shows a configuration example in which the protection circuit (231) includes a plurality of protection circuit resonance inductors. Compared to the first embodiment, the determination circuit (225) detects a excessive input and outputs a second switching unit (726) that is short-circuited by a signal that is output, and a second switching unit (726) that is connected in series to the second switching unit (726). A protection circuit resonance inductor (727) is provided, and a second switching unit (726) and a second protection circuit resonance inductor (727) connected in series are connected to an antenna resonance capacitor (228) and (first ) Connect in parallel with inductor (227) for resonance of protection circuit. Furthermore, the judgment circuit (225) has two judgment thresholds for excessive input, and when the first threshold is exceeded, the (first) switching unit (226) is short-circuited and exceeds the second threshold. To short-circuit the second switching unit (726). Further, the second threshold is set higher than the first threshold.

  In addition, the (first) switching unit (226) and the second switching unit (726) are short-circuited so that the antenna resonance capacitor (228), the (first) protection circuit resonance inductor (227), the second The impedance of the second protection circuit (732) formed by the protection circuit resonance inductor (727) is short-circuited only by the (first) switching unit (226), and the antenna resonance capacitor (228), (first ) Set higher than the impedance of the first protection circuit (731) formed by the protection circuit resonance inductor (227).

  According to this configuration, when the level of the power wave (200) received by the power receiving device (220) increases, the determination circuit (225) first detects the first threshold value and detects the first protection circuit ( 731) to reduce the reception efficiency of the power wave (200).

  When the level of the power wave (200) further increases, the determination circuit (225) detects the second threshold value to form a second protection circuit, and further increases the impedance of the protection circuit to increase the power wave (200). The reception efficiency is further reduced.

  According to this configuration, the reception efficiency of the power wave (200) can be reduced stepwise by increasing the impedance of the protection circuit (231) in response to an increase in the level of the power wave received by the power receiving device (220). I can do it.

  The number of protection circuit resonance inductors may be three or more, and the reception efficiency can be suppressed in multiple stages as the number increases.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

122 Power receiver
123 Judgment part
200 power wave
210 Power feeder
211 Power source
212 Feed antenna
220 Power receiving device
221 Power receiving antenna
223 Rectifier circuit
224 Load circuit
225 judgment circuit
226 Switching section
227 Inductor for protection circuit resonance
228 Antenna resonance capacitor
230 Antenna circuit
231 Protection circuit
322 Capacitor for antenna parallel resonance
330 Parallel resonant antenna circuit
427 Capacitor for protection circuit resonance
428 Antenna inductor for protection circuit
532 High impedance circuit
626 Second switching part
627 Inductor for resonance of second protection circuit
628 Second antenna resonance capacitor
631 Second protection circuit
726 Second switching part
727 Second protection circuit resonance inductor
731 First protection circuit
732 Second protection circuit
826 variable resistance
829 MOSFET830 n-channel MOSFET
831 diode

Claims (8)

In a power receiving device including a power receiving antenna for receiving a power wave output from a power feeding device, and a power receiving unit that uses power received by being connected to the power receiving antenna,
A determination unit that monitors the operation of the power reception unit and detects an excessive input of power; and
A protection circuit that is connected in series to the power receiving antenna and increases impedance at both ends in accordance with the output of the determination unit;
The power receiving device, wherein when the determination unit detects an excessive input of power, the reception efficiency of the power receiving antenna is decreased by increasing impedances at both ends of the protection circuit. The power receiving device according to claim 1,
The power receiving antenna includes one or more antenna resonance capacitors connected in series;
The power receiving unit includes a rectifier circuit that rectifies a power wave received by the power receiving antenna, and a load circuit that operates at the output of the rectifier circuit,
The determination unit includes a determination circuit that monitors an output of the rectifier circuit or an operation of the load circuit, detects an excessive input of a power wave, and outputs a detection signal thereof,
The protection circuit includes a switching unit that reduces impedance at both ends when the determination circuit receives the detection signal that is output by detecting an excessive input, and a protection circuit resonance inductor connected in series,
A power receiving device, wherein the protection circuit is connected in parallel to at least one of the antenna resonance capacitors. The power receiving device according to claim 2,
When the detection circuit receives the detection signal output when detecting an excessive input, and the switching unit decreases the impedance at both ends, the impedance at both ends of the antenna resonance capacitor increases. Power receiving device. The power receiving device according to claim 1,
The power receiving antenna includes at least one protection circuit antenna inductor connected in series;
The power receiving unit includes a rectifier circuit that rectifies a power wave received by the power receiving antenna, and a load circuit that operates at the output of the rectifier circuit,
The determination unit includes a determination circuit that monitors an output of the rectifier circuit or an operation of the load circuit, detects an excessive input of a power wave, and outputs a detection signal thereof,
The protection circuit comprises a switching unit for reducing impedance at both ends by the detection signal output by the determination circuit detecting and outputting an excessive input, and a protection circuit resonance capacitor connected in series,
A power receiving device, wherein the protection circuit is connected in parallel to at least one of the protection circuit antenna inductors. The power receiving device according to claim 4,
When the determination unit receives the detection signal output when detecting an excessive input, and the switching unit decreases the impedance at both ends, the impedance at both ends of the antenna inductor for protection circuit is increased. Power receiving device. The power receiving device according to any one of claims 2 to 5,
The determination circuit, when monitoring the output of the rectifier circuit or the operation of the load circuit and detecting an excessive input of a power wave, outputs a plurality of types of detection signals according to the degree of the excessive input,
The switching unit reduces impedance at both ends according to the type of the received detection signal. The power receiving device according to claim 1,
A rectifier circuit for rectifying the received power connected to the power receiving antenna;
A load circuit operating at the output of the rectifier circuit;
A switching unit connected in series between the power receiving antenna and the rectifier circuit;
A protection circuit connected in parallel to the switching unit,
The determination unit includes a determination circuit that monitors an output of the rectifier circuit or an operation of the load circuit, detects an excessive input, and outputs a detection signal;
The power receiving device, wherein the determination circuit detects an excessive input and raises impedances at both ends of the switching unit by the detection signal output. The power receiving device according to claim 7, wherein
A power receiving device, wherein a high impedance circuit having a high impedance is connected in parallel to the switching unit.

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