JP7270212B2 - wireless power supply - Google Patents

Description

The present invention relates to a wireless power feeding device.

For example, factory facilities such as robots and AGVs (Automated Guided Vehicles) are surrounded by a large number of conductors such as metal. In the case of a wireless power supply device using electric field coupling, a high frequency of several MHz is used. Therefore, a class E inverter including a push-pull type inverter is used as a high frequency generator for generating high frequency.

Such inverters are designed for ZVS (Zero Voltage Switching) at optimum loads in order to reduce losses. Therefore, when the inverter operates in a region different from this optimum load, ZVS becomes difficult, loss occurs during switching, and efficiency decreases. That is, when the load of the load device to which power is supplied changes, ZVS becomes difficult due to the change in impedance, resulting in a decrease in efficiency. Therefore, in the case of a load device such as an actuator such as a motor that involves load fluctuations, it is essential to combine a battery or the like to keep the impedance constant on the side to which power is supplied from the high-frequency generator. Become.

However, in the case of a robot, for example, having a plurality of loads that fluctuate greatly, combining a battery or the like for each load poses a problem of increasing the physical size and weight.

JP 2019-17151 A

Therefore, it is an object of the present invention to provide a wireless power supply device that reduces loss during switching and reduces efficiency deterioration even when the load fluctuates.

The wireless power feeding device of this embodiment includes an impedance changing circuit section. The impedance changing circuit section is provided on the output side of the high frequency generating section. A load device that receives electric power from a high-frequency generator through a transmission unit that uses wireless power supply based on electric field coupling varies in impedance as the load varies depending on the operating state of the device. The impedance changing circuit section changes the impedance in the high-frequency generating section in accordance with the impedance variation caused by the load variation in the load device. In other words, the impedance changing circuit unit adjusts the impedance of the high-frequency generation unit to a high-efficiency region with high efficiency even if the impedance fluctuates due to changes in the load of the load device by changing the impedance of the high-frequency generation unit. . In other words, the impedance in the operating region of the load device overlaps with the impedance in the high efficiency region of the high frequency generator. Therefore, even when the load of the load device fluctuates, it is possible to reduce the loss during switching of the high-frequency generator and reduce the decrease in efficiency.

Schematic diagram showing the electrical circuit configuration of the wireless power feeder according to the first embodiment Schematic diagram showing impedance characteristics of the wireless power supply device according to the first embodiment Schematic diagram showing impedance characteristics of a wireless power feeder without an impedance changing circuit Schematic diagram showing the relationship between the load and power in the wireless power supply device according to the first embodiment and the comparative example Schematic diagram showing an equivalent circuit of the wireless power feeder according to the first embodiment Schematic diagram showing an equivalent circuit of the wireless power feeder according to the second embodiment Schematic diagram showing an electrical circuit configuration of a wireless power supply device according to a third embodiment Schematic diagram showing a modification of the impedance changing circuit unit of the wireless power supply device according to the third embodiment

A plurality of embodiments of the wireless power feeder will be described below with reference to the drawings.
(First embodiment)
A wireless power supply device 10 according to the first embodiment shown in FIG. The wireless power supply device 10 supplies electric power from the high frequency generator 11 to the load device 13 in a non-contact manner via the transmission unit 12 .

In the case of the first embodiment, the high frequency generator 11 is composed of a class E inverter. The high frequency generator 11 generates high frequency using power supplied from the power supply 15 . The transmission unit 12 is provided on the output side of the high frequency generation unit 11 and transmits the high frequency generated by the high frequency generation unit 11 . The transmission section 12 has a power transmission electrode section 16 and a power reception electrode section 17 . The power transmitting electrode portion 16 and the power receiving electrode portion 17 face each other without contacting each other. The transmission unit 12 transmits power to the power receiving electrode unit 17 in a non-contact manner using electric field coupling by outputting a high frequency signal from the power transmitting electrode unit 16 . The load device 13 operates with power transmitted via the transmission unit 12 . The load device 13 has, for example, a motor, an actuator, and the like, and the power it consumes fluctuates over time as it operates. The impedance of the load device 13 changes as the power it consumes fluctuates. Note that the load device 13 may have a rectifying section (not shown) that rectifies the power transmitted via the transmitting section 12 .

The impedance changing circuit section 14 is provided between the high frequency generating section 11 and the load device 13 . More specifically, the impedance changing circuit section 14 is provided between the high frequency generation section 11 and the transmission section 12 . When the impedance of the load device 13 side rather than the transmission section 12 changes due to the variation of the load RL of the load device 13, the impedance change circuit section 14 changes the impedance of the high frequency generation section 11 side rather than the transmission section 12 in accordance with the impedance variation. change the impedance of

The impedance changing circuit section 14 is a so-called gyrator, and has, for example, a λ/4 type low-pass filter as shown in FIG. As a result, the impedance changing circuit section 14 inverts the impedance characteristic associated with the change in the load of the load device 13 as will be described later. That is, by providing the impedance changing circuit unit 14 between the high frequency generator 11 and the load device 13, when the impedance on the load device 13 side fluctuates, the impedance on the high frequency generator 11 side is changed according to this fluctuation. As a result, by providing the impedance changing circuit unit 14 between the high frequency generation unit 11 and the load device 13, the input power supplied from the power supply 15 to the high frequency generation unit 11 is output from the high frequency generation unit 11 to the load device 13. It fluctuates according to the output power applied.

The relationship between the input power input to the high frequency generator 11 and the output power output from the high frequency generator 11 is as shown in FIGS. As described above, the impedance of the load device 13 fluctuates over time as the load RL of the load device 13 fluctuates. The high frequency generator 11 using a class E inverter is designed to be ZVS when the load RL in the load device 13 becomes the optimum load Ro. That is, when the load device 13 becomes the optimum load Ro, the high-frequency generator 11 maximizes the input power Wi input from the power supply 15 and the output power Wo output to the load device 13 as shown in FIGS. The impedance characteristics are as follows.

The high-frequency generator 11 without the impedance changing circuit 14 is in a high efficiency region with high efficiency when the varying impedance of the load device 13 is in the region below the optimum load Ro as shown in FIG. On the other hand, the load device 13 operates in a working range in which the impedance is equal to or higher than the minimum load RLm. The minimum load RLm corresponds to the minimum value of the load RL assumed in the load equipment 13 in the operating area, and is set larger than the optimum load Ro. If the impedance changing circuit section 14 is not provided, the difference between the input power Wi and the output power Wo becomes large in the actual working range as shown in FIG. The divergence between the input power Wi and the output power Wo in this manner causes switching loss in the high-frequency generation unit 11, resulting in a decrease in efficiency. In other words, when the impedance changing circuit section 14 is not provided, the efficiency of power transmission from the high-frequency generation section 11 to the load device 13 decreases in the actual operating range of the load device 13 . Therefore, generally, it is necessary to drive the load device 13 through a power storage unit such as a battery in order to keep the impedance of the load device 13 constant. Since the power storage unit and the like cause an increase in weight and size, it is difficult to apply the wireless power supply device 10 to a device, such as a robot, in which the load fluctuates.

On the other hand, when the impedance changing circuit section 14 is provided as in the first embodiment, the impedance characteristic with respect to the impedance variation of the load device 13 is reversed. That is, when the impedance of the load device 13 fluctuates as shown in FIG. 2, the relationship between the input power Wi and the output power Wo is reversed from the example shown in FIG. 3 with the optimum load Ro as the boundary. Thus, in the case of the first embodiment, the input power Wi input to the high frequency generator 11 follows the output power Wo output from the high frequency generator 11 in the operating range of the load device 13 . That is, in a region where the impedance of the load device 13 is higher than the region where the output power Wo of the high frequency generation unit 11 is maximized, the impedance change circuit unit 14 reduces the input power Wi following the output power Wo. As a result, the divergence between the input power Wi and the output power Wo in the operating region of the load device 13 becomes small, and the operating efficiency of the high frequency generator 11 and the efficiency of power transmission from the high frequency generator 11 to the load device 13 are high. area.

As described above, in the case of the first embodiment including the impedance changing circuit section 14, the active region of the load device 13 and the high efficiency region of the high frequency generating section 11 overlap. Therefore, the efficiency of power transmission from the high frequency generator 11 to the load device 13 is improved. In other words, as shown in FIG. 4, in the case of the first embodiment, the input power Wi changes following the output power Wo that changes with the load RL of the load device 13 . On the other hand, in the configuration without the impedance changing circuit section 14, which is the comparative example, even if the output power Wo changes, the input power Wix does not follow. This also reveals that the power transmission efficiency is improved when the impedance changing circuit unit 14 is provided as in the first embodiment.

In the case of the first embodiment, the impedance changing circuit section 14 is a so-called Π type as shown in FIG. That is, the impedance changing circuit section 14 has a capacitor 21 , a capacitor 22 and a coil 23 . In the equivalent circuit as shown in FIG. 5, the capacitances of capacitors 21 and 22 and the inductance of coil 23 are calculated by the following equations (1) to (3). In this case, the capacitors 21 and 22 are set to "jX1" shown in FIG. 5, the coil 23 is set to "jX2" shown in FIG. 5, and the following formulas (1) to (3) are applied. Hereinafter, "j" indicates an imaginary number.

In equation (1) above, Ro is the optimum load and RLm is the minimum load. Also, f is the frequency of the high frequency generated by the high frequency generator 11 . It should be noted that the elements in the impedance changing circuit section 14 as shown in FIG. 1 are only examples, and any element other than the capacitor 21, the capacitor 22 and the coil 23 can be used as long as it satisfies the above equations (1) to (3). can be applied.

The wireless power feeding device 10 of the first embodiment described above includes the impedance changing circuit section 14 . The impedance changing circuit section 14 is provided between the high frequency generating section 11 and the load device 13 . The impedance changing circuit unit 14 changes the input power Wi input from the power supply 15 to the high frequency generator 11 according to the output power Wo supplied from the high frequency generator 11 to the load device 13 . That is, the impedance changing circuit unit 14 changes the impedance characteristics in the high-frequency generation unit 11 side of the transmission unit 12, thereby changing the impedance characteristics in the operating region of the load device 13 to the high-efficiency region where the high-frequency generation unit 11 has high efficiency. match. That is, by providing the impedance changing circuit section 14 , the effective operating region of the load device 13 overlaps with the high efficiency region of the high frequency generating section 11 . Therefore, even when the load RL of the load device 13 varies and the impedance on the load device 13 side changes, the loss during switching of the high frequency generator 11 can be reduced, and the decrease in efficiency can be reduced.

Further, in the first embodiment, the impedance changing circuit unit 14 causes the input power Wi to follow the output power Wo in a region where the impedance of the load device 13 is greater than the region where the output power Wo of the high frequency generation unit 11 is the maximum value. to lower. That is, the impedance changing circuit section 14 functions as a gyrator. Therefore, the relationship between the input power Wi and the output power Wo is inverted with a simple circuit. Therefore, it is possible to reduce the loss during switching of the high-frequency generator 11 and reduce the decrease in efficiency without complicating the structure.

Furthermore, in the first embodiment, the impedance changing circuit section 14 is provided between the high frequency generation section 11 and the transmission section 12 . As a result, for example, when the wireless power supply device 10 is applied to a robot, the impedance changing circuit unit 14 is added to the power transmission electrode unit 16 side, which is the fixed side, and an additional circuit is required to the power reception electrode unit 17 side, which is the movable side. does not become Therefore, an increase in the weight of the movable side and an increase in physical size are not caused. Therefore, even if the load RL of the load device 13 on the movable side fluctuates, as in a robot, for example, it is possible to reduce the decrease in efficiency without increasing the weight and size.

(Second embodiment)
FIG. 6 shows a wireless power supply device 10 according to the second embodiment.
In the case of the second embodiment, the configuration of the impedance changing circuit section 14 is different from that of the first embodiment. In the case of the second embodiment, as shown in FIG. 6, the impedance changing circuit section 14 is of T type. In the case of the first embodiment, the elements forming the impedance changing circuit section 14 form a Π type consisting of a pair of elements inserted in parallel and one element inserted in series. On the other hand, in the case of the second embodiment, the elements constituting the impedance changing circuit section 14 are a T-shaped element composed of a pair of elements 31 and 32 inserted in series and one element 33 inserted in parallel. constitutes Arbitrary elements such as capacitors and coils can be applied to these elements 31 to 33 as long as they function as a T-shaped gyrator. In this case, the elements 31 and 32 are set to "jX1" shown in FIG. 6, the element 33 is set to "jX2" shown in FIG. 6, and the above equations (1) to (3) are applied.
As described above, the elements constituting the impedance changing circuit section 14 can have any circuit configuration as long as they have the function of inverting the impedance characteristics.

(Third Embodiment)
FIG. 7 shows a wireless power supply device 10 according to the third embodiment.
In the case of the third embodiment, as shown in FIG. 7, the high frequency generator 11 is composed of a class E push-pull inverter. The wireless power feeding device 10 according to such a third embodiment has an impedance changing circuit section 14 . The high-frequency generator 11, which is composed of a class E push-pull inverter, has a differential output power Wo. Therefore, the impedance changing circuit section 14 is also differential in accordance with the high frequency generating section 11 which is differential. That is, the impedance changing circuit section 14 has capacitors 41 and 42 inserted in parallel, and coils 43 and 44 inserted in series as elements constituting a gyrator. In this case, the capacitors 41 and 42 are "jX1" shown in FIG. 7, the coils 43 and 44 are "(jX2)/2" shown in FIG. 7, and the above equations (1) to (3) are applied. do.

In this way, the high-frequency generator 11 can apply not only the class E inverter but also the class E push-pull inverter. When using such a class E push-pull inverter, not only the Π-type impedance change circuit unit 14 shown in FIG. 7 but also the T-type impedance change circuit unit 14 shown in FIG. 8 can be applied. can also In the case of the T-type impedance changing circuit section 14 shown in FIG. 8, the coils 51, 52, 53 and 54 are set to "(jX1)/2" shown in FIG. 8, and the capacitor 55 is set to "jX2" shown in FIG. , the above equations (1) to (3) are applied.

The present invention described above is not limited to the above-described embodiments, and can be applied to various embodiments without departing from the gist of the present invention.
The wireless power supply device 10 according to the plurality of embodiments described above can be applied to a device, such as a robot, in which the load of the motor or actuator, which is the load device 13, fluctuates. For example, in the case of a three-axis robot, by providing the impedance changing circuit unit 14 on the fixed side, the motor and actuator side, which are movable parts, do not require a power storage unit such as a battery. Therefore, it does not lead to an increase in the size and mass of the movable parts of the robot. Therefore, the wireless power supply device 10 can be applied to the robot without increasing the output or increasing the size.
Although the present disclosure has been described with reference to examples, it is understood that the present disclosure is not limited to such examples or structures. The present disclosure also includes various modifications and modifications within the equivalent range. In addition, various combinations and configurations, as well as other combinations and configurations, including single elements, more, or less, are within the scope and spirit of this disclosure.

In the drawing, 10 is a wireless power supply device, 11 is a high frequency generator, 12 is a transmission unit, 13 is a load device, 14 is an impedance change circuit, 15 is a power source, 16 is a power transmission electrode, and 17 is a power reception electrode.

Claims (1)

a high-frequency generator (11) that generates high-frequency power;
It has a power transmission electrode section (16) and a power reception electrode section (17), and the high frequency power generated by the high frequency generation section (11) is transferred from the power transmission electrode section (16) to the power reception electrode section (17) using electric field coupling. 17) a transmission unit (12) for contactlessly transmitting power to
a load device (13) operated by power received from the high frequency generator (11) through the transmitter (12);
provided between the transmission section (12) on the output side of the high-frequency generation section (11) and adapted to change the impedance of the load device (13) due to changes in the load on the load device (13); In addition, an impedance changing circuit unit (14) for changing impedance between a power source (15) for supplying power and the transmission unit (12) ;
with
When the input power input from the power supply (15) to the high-frequency generator (11) is defined as Wi, and the output power output from the high-frequency generator (11) to the load device (13) is defined as Wo ,
The high-frequency generator (11) is set to have impedance characteristics such that when the load RL of the load device (13) is the optimum load Ro, the input power Wi and the output power Wo are maximum ZVS,
The optimum load Ro is a region in which the output voltage Wo of the high frequency generator (11) is maximized,
The impedance changing circuit section (14) functions as a gyrator that inverts the impedance between the high frequency generating section (11) and the transmitting section (12) with respect to the impedance change on the load device (13) side. , with the optimum load Ro as a boundary, a wireless system that makes the difference between the input power Wi and the output power Wo smaller in a region where the impedance of the load device (13) is large than in a region where the impedance of the load device (13) is small. Power supply.

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