Patent ID: 12224629

DESCRIPTION OF THE EMBODIMENTS

Exemplary embodiments are described in detail below with reference to the drawings. The following exemplary embodiments are not intended to limit the claims. While a plurality of characteristics is described in the exemplary embodiments, not all of the plurality of characteristics is necessarily essential, and the plurality of characteristics may be freely combined. Further, in the drawings, the same or similar components are denoted by the same reference numerals, and repetitive descriptions thereof are omitted.

[System Configuration]

FIG.1is a block diagram illustrating a configuration example of a control system300according to a first exemplary embodiment.

The control system300includes a power transmission unit100, a power reception unit200, an alternating-current power supply401, and a motor402. The power transmission unit100and the power reception unit200are not physically connected. Power is transmitted from a power transmission antenna101to a power reception antenna201in a contactless manner. The power transmission antenna101and the power reception antenna201are coupled by magnetic field coupling. However, the antennas may be coupled by electric field coupling, or an electromagnetic field coupling.

The control system300is, for example, a semiconductor exposure apparatus. A motor402is mounted on a stage for moving a wafer to an exposure position. The motor402finely moves the wafer to form a pattern on the wafer.

The power transmission unit100includes the power transmission antenna101, a switch circuit102, a current detection unit103, and a control unit104. The control unit104detects a current supplied from the alternating-current power supply401, and feeds back a current detection result to the alternating-current power supply401. The alternating-current power supply401supplies an alternating-current voltage to the switch circuit102based on the current detection result. The switch circuit102switches the alternating-current voltage supplied from the alternating-current power supply401with a frequency higher than a frequency of the alternating-current voltage supplied from the alternating-current power supply401, and outputs the switched voltage to the power transmission antenna101. The power transmission antenna101wirelessly transmits power to the power reception antenna201through magnetic field coupling.

The power reception unit200includes the power reception antenna201and a rectification circuit202. The power reception antenna201wirelessly receives the power wirelessly transmitted from the power transmission antenna101. The rectification circuit202rectifies the power wirelessly received by the power reception antenna201, and restores a waveform of the alternating-current voltage supplied by the alternating-current power supply401. The switch circuit102, the power transmission antenna101, the power reception antenna201, and the rectification circuit202form a resonance circuit to efficiently perform wireless power transmission.

The motor402is driven based on the alternating-current voltage restored by the rectification circuit202, and moves the wafer and the like.

FIG.2is a perspective view illustrating an appearance example of the control system300according to the first exemplary embodiment. The control system300includes the power transmission antenna101, the switch circuit102, the power reception antenna201, the rectification circuit202, the motor402, and a stage502.

The power reception antenna201and the rectification circuit202are mounted on the stage502. The motor402is a linear motor and moves the stage502. Positions of the power transmission antenna101, the switch circuit102, and the motor402are fixed. The power reception antenna201is movable relative to the power transmission antenna101. The power transmission antenna101has a length longer than a length of the power reception antenna201. The power transmission antenna101and the power reception antenna201face each other in a contactless manner while the stage502moves to any position. Accordingly, while the stage502is located at any position, the power reception antenna201can wirelessly receive the power from the power transmission antenna101.

The control unit104outputs an instruction value of an output value of the alternating-current voltage to the alternating-current power supply401. For example, the control unit104calculates the instruction value of the output value of the alternating-current voltage based on the current detected by the current detection unit103, and outputs the instruction value of the output value of the alternating-current voltage to the alternating-current power supply401. The control unit104can calculate the instruction value of the output value of the alternating-current voltage based on positional information on the stage502or a predetermined instruction sequence in addition to the current detected by the current detection unit103. The positional information on the stage502is described in detail in a second exemplary embodiment.

The current detection unit103detects an instantaneous value of an alternating current flowing from the alternating-current power supply401to the switch circuit102, and outputs the instantaneous value of the alternating current to the control unit104. The control unit104varies the output value of the alternating-current voltage of the alternating-current power supply401based on the instantaneous value of the alternating current. In a case where the detected instantaneous value of the alternating current is less than a desired current value, the control unit104increases the output value of the alternating-current voltage of the alternating-current power supply401. In a case where the detected instantaneous value of the alternating current s greater than the desired current value, the control unit104reduces the output value of the alternating-current voltage of the alternating-current power supply401.

[Waveform of Motor Driving Voltage Wirelessly Transmitted]

Before the desired current value is described in detail, the alternating-current voltage for driving the motor402is described. To rotate the motor402in a forward rotation direction or a reverse rotation direction, it is necessary to change the voltage applied to the motor402to a positive voltage or a negative voltage. In other words, application of the alternating-current voltage to the motor402makes it possible to control a rotation direction of the motor402.

In the system discussed in Japanese Patent Application Laid-Open No. 2018-54847, the alternating-current voltage to control the rotation direction of the motor402is generated by the power reception unit200, and a direct-current voltage is applied from a direct-current power supply to the power transmission unit100. The power transmission unit100supplies the direct-current voltage to the power reception unit200by wireless power transmission, and the direct-current voltage is supplied to a motor driver in the power reception unit200. Further, the motor driver generates the alternating-current voltage to control the rotation direction of the motor402. The feedback control is performed such that a value of the direct-current voltage supplied to the motor driver is maintained at a constant value against fluctuation caused by variation in a load current, external noise, or the like.

Unlike the configuration of the system discussed in Japanese Patent Application Laid-Open No. 2018-54847, in the control system300according to the present exemplary embodiment, no motor driver is provided in the power reception unit200, and the power reception unit200has a small size. The alternating-current power supply401corresponds to the motor driver. The alternating-current power supply401applies the alternating-current voltage to control the rotation direction of the motor402, to the power transmission unit100. The power transmission unit100supplies power based on the alternating-current voltage to the power reception unit200by the wireless power transmission. The power reception unit200restores the alternating-current voltage of the alternating-current power supply401based on the received power, and applies the restored alternating-current voltage to the motor402. Thus, the current detected by the current detection unit103for feedback control is the alternating current, and the voltage controlled by the alternating-current power supply401is the alternating-current voltage.

[Desired Current Value]

Next, the above-described desired current value is described. The desired current value or voltage value described here means a current value or voltage value necessary to implement a function. For example, in the semiconductor exposure apparatus, the desired current value or voltage value indicates a current value or voltage value to be applied to the motor402in order to move the stage502to a position necessary for formation of a pattern on the wafer.

In a case where the feedback control is performed to maintain the constant direct-current voltage value supplied to the power reception unit200as in Japanese Patent Application Laid-Open No. 2018-54847, a desired voltage value is an invariable constant value because of direct current. Thus, a difference between the desired direct-current voltage value and the direct-current voltage value actually supplied is determined, and the direct-current voltage value of the power transmission unit100is varied so as to reduce the difference. Under such control, the direct-current voltage value supplied to the power reception unit200is maintained at the desired direct-current voltage value.

In contrast, since the power transmission unit100according to the present exemplary embodiment supplies the alternating-current voltage to the power reception unit200by the wireless power transmission, the desired voltage value is not a constant value and is varied with time. For example, it is necessary for the motor402that positions the stage502of the semiconductor exposure apparatus to move the stage502to various positions with time. Thus, it is necessary to apply the voltage of various values including a positive voltage or a negative voltage. In a case where a control period is 10 kHz, the desired voltage value is varied to a value including a positive voltage and a negative voltage, and is varied every 100 μs. To control the position of the stage502with high accuracy, it is necessary to accurately apply the voltage value to the motor402every 100 μs. Thus, it is necessary for the control unit104to perform the feedback control every 100 μs.

[Fluctuation Factor]

The alternating-current voltage supplied to the power reception unit200by the wireless power transmission is fluctuated by an external factor. For example, when the power transmission unit100or the power reception unit200receives electromagnetic noise generated from another motor or the like inside the apparatus, the alternating-current voltage supplied to the power reception unit200is fluctuated.

Since the power reception unit200moves together with the stage502, an electromagnetic environment around the power transmission antenna101and the power reception antenna201is changed depending on the position of the stage502, and the alternating-current voltage supplied to the power reception unit200by the wireless power transmission is accordingly fluctuated. In particular, intensity of the electromagnetic field to which the power reception antenna201is subjected is different between a case where the power reception antenna201moves to an end part of the power transmission antenna101and a case where the power reception antenna201moves to a center part of the power transmission antenna101, which fluctuates the alternating-current voltage supplied to the power reception unit200.

Further, when the stage502moves, acceleration is applied. Thus, physical distortion occurs in the stage502, and a distance between the power transmission antenna101and the power reception antenna201changes. The distance relates to a coupling coefficient between the power transmission antenna101and the power reception antenna201, and the coupling coefficient largely influences transmission efficiency of the wireless power transmission. Thus, when acceleration is applied to the stage502, the coupling coefficient changes, and the alternating-current voltage supplied to the power reception unit200by the wireless power transmission is fluctuated.

[Feedback Control]

To suppress such fluctuations and to apply an accurate voltage to the motor402every 100 μs, it is necessary to complete the feedback control within 100 μs. More specifically, the control system300detects the instantaneous value of the alternating-current voltage supplied to the power reception unit200, wirelessly transmits the instantaneous value of the alternating-current voltage to the power transmission unit100, compares the instantaneous value with the desired voltage value, and calculates a difference generated by fluctuation caused by an external factor. Then, the control system300controls the output value of the alternating-current voltage of the alternating-current power supply401based on the difference. Further, it is necessary for the control system300to continue the operation without delay for subsequent 100 μs and after.

In a case where the instantaneous value of the alternating-current voltage being supplied to the power reception unit200is transmitted from the power reception unit200to the power transmission unit100by the wireless communication as in the system discussed in Japanese Patent Application Laid-Open No. 2018-54847, if the wireless communication is delayed by 100 μs, the feedback control cannot be performed within 100 μs. A time for packet processing or for processing of error correction depending on a radio wave environment is necessary for the wireless communication. The delay by the processing time is generally 1 ms or more, and thus the feedback control using the wireless communication cannot be performed on high-speed control, for example, at 10 kHz. Thus, the feedback control is delayed, and it is not possible to quickly respond to fluctuation of the alternating-current voltage supplied to the power reception unit200. As a result, the fluctuation cannot be suppressed in some cases.

The control unit104according to the present exemplary embodiment feeds back the alternating current detected by the current detection unit103provided in the power transmission unit100to the alternating-current power supply401, and controls the output value of the alternating-current voltage of the alternating-current power supply401. In this configuration, the feedback control is closed only in the power transmission unit100. Thus, it is unnecessary to use the wireless communication from the power reception unit200, and delay in control caused by the above-described delay does not occur. Accordingly, the feedback control can be performed at high speed, and the voltage applied to the motor (load unit)402can be controlled with high accuracy based on power supplied by the wireless power transmission.

A principle in which the control unit104performs the feedback control on the output value of the alternating-current voltage of the alternating-current power supply401based on the alternating current of the power transmission unit100to suppress the fluctuation of the voltage applied to the motor402is described. Briefly, the motor can be regarded as a fixed inductor. Thus, a relationship between the voltage applied to the motor402and the current is uniquely determined, and the voltage value can be estimated from the current value. Thus, when the alternating current of the power transmission unit100correlated with the current flowing through the motor402is known, the voltage applied to the motor402is known, and thus how to vary the output value of the alternating-current voltage of the alternating-current power supply401is known.

More specifically, to enable the control unit104to perform the feedback control on the output value of the alternating-current voltage of the alternating-current power supply401based on the alternating current of the power transmission unit100, it is necessary to derive a relational expression between the voltage applied to the motor402and the alternating current of the power transmission unit100. To vary the voltage value applied to the motor402to the desired voltage value, the control unit104calculates a target value of the alternating current, namely, the desired current value, based on the relational expression and calculates a difference between the desired current value and the instantaneous value of the current alternating current. Further, the control unit104varies the output value of the alternating-current voltage of the alternating-current power supply401so as to bring the difference close to zero.

In a case where a routine operation of the stage502is repeated in the semiconductor exposure apparatus or the like, a desired waveform of the voltage to be applied to the motor402is known. Thus, the desired current value of the alternating current of the power transmission unit100may be determined by preliminary measurement. More specifically, the desired current value is determined by applying the voltage in a sequence of actually driving the motor402while the stage502is stopped, and measuring the alternating current of the power transmission unit100at that time. Then, in actual operation, the control unit104varies the output value of the alternating-current voltage of the alternating-current power supply401by a difference between the instantaneous value of the current alternating current and the desired current value due to the above-described fluctuation factor.

To determine a variation amount of the output value of the alternating-current voltage of the alternating-current power supply401, a relationship between the output value of the alternating-current voltage and a variation amount of the alternating current may be determined by preliminary measurement.

Since it is necessary for the current detection unit103to detect the alternating current, the current detection unit103desirably includes a differential input detection circuit that can detect a negative voltage. In a case where the current detection unit103measures the current value by using a shunt resistance, an input-output isolation detection circuit may be used because a common mode voltage is high in a motor driving circuit or the like.

As described above, the alternating-current power supply401applies the alternating-current voltage to the switch circuit102under the control of the control unit104. The switch circuit102switches the alternating-current voltage. The power transmission antenna101wirelessly transmits power based on the alternating-current voltage switched by the switch circuit102. The power reception antenna201wirelessly receives the power wirelessly transmitted from the power transmission antenna101. The rectification circuit202rectifies the voltage output from the power reception antenna201, and applies the alternating-current voltage to the motor402. The motor402is an example of the load unit.

The current detection unit103detects the alternating current flowing through the switch circuit102. The control unit104controls a value of the alternating-current voltage applied to the switch circuit102via the alternating-current power supply401based on the current value detected by the current detection unit103. More specifically, the control unit104controls the value of the alternating-current voltage applied to the switch circuit102via the alternating-current power supply401based on the difference between the current value detected by the current detection unit103and the target value. At least one of the power transmission antenna101and the power reception antenna201is movable. The above-described target value is a target value based on the movement sequence.

According to the present exemplary embodiment, the control system300supplies power from the power transmission antenna101to the power reception antenna201by the wireless power transmission. The control unit104can control the voltage applied to the motor402with high accuracy. The control system300can perform the wireless power transmission on the motor402, and can control the alternating-current voltage applied to the motor402with high accuracy.

Next, a control system300according to a second exemplary embodiment is described. Hereinafter, a difference between the second exemplary embodiment and the first exemplary embodiment will be described. In the control system300according to the second exemplary embodiment, feedforward control of the alternating-current power supply401based on the positional information on the stage502is added to the control system300illustrated inFIG.1. The control system300suppresses part of the fluctuation by the feedforward control. As a result, a fluctuation amount to be suppressed by the feedback control is reduced, and the motor402can be controlled with higher accuracy.

Next, a fluctuation factor suppressed by addition of the feedforward control based on the positional information is described. InFIG.2, the stage502reciprocates on one axis by the motor402, and the power reception antenna201reciprocates above the power transmission antenna101along with the reciprocation of the stage502.

FIG.3is a diagram illustrating an example of a measurement result of the voltage value output from the rectification circuit202of the power reception unit200by the wireless power transmission, relative to a position of the power reception antenna201. To check the fluctuation amount of the output voltage with respect to the position of the power reception antenna201separately from influence by vibration and the like during the reciprocation of the stage502, the output voltage is measured in a state where the power reception antenna201is moved by 1 mm and is then stopped. The output voltage of the alternating-current power supply401is fixed to the direct-current voltage of 1 V, and an output node of the rectification circuit202is connected to a resistance load of 10Ω. A length of the power transmission antenna101is 600 mm, a length of the power reception antenna201is 100 mm, and a movable stroke of the power reception antenna201is 500 mm. The measurement results inFIG.3are results for the positions of the power reception antenna201between 50 mm and 450 mm. Two types of plots, namely, white circles and black triangles, indicate results measured twice under the same condition.

It is found from the results inFIG.3that an average of output voltages of the rectification circuit202is 1.076 V. It is found that the output voltages of the rectification circuit202is fluctuated by about 14 mV (1.3%) relative to the average (1.076 V) depending on the position of the power reception antenna201. Factors of the fluctuation include manufacturing variation of a material (permittivity, dielectric loss tangent, permeability, etc.) and a shape (substrate thickness, conductor thickness, resist thickness, etc.) with respect to the position of the power transmission antenna101, and fluctuation of the distance between the power transmission antenna101and the power reception antenna201caused by mechanical tolerance of the motor402. It is difficult to completely eliminate the fluctuation.

With regard to the two types of plots, a difference between the two measurement results is 4 mV (0.4%) at a maximum, and the fluctuation of the output voltage in the wireless power transmission with respect to the position of the power reception antenna201has reproducibility. Thus, the feedforward control in which the fluctuation amount is preliminarily measured as inFIG.3, and the motor402is controlled by considering the fluctuation amount as a correction value is performable.

The feedforward control is described in detail. The control unit104calculates an instruction value to move the stage502to a next position based on the current positional information on the stage502and the like. Then, the control unit104transmits the instruction value to the alternating-current power supply401. The alternating-current power supply401varies the output value of the alternating-current voltage to be output based on the instruction value. As an example, a case is considered where a certain constant voltage value is continuously applied to the motor402while the motor402moves the power reception antenna201on the stage502from a position of 100 mm to a position of 400 mm illustrated inFIG.3. In a case where the output voltage is not fluctuated with respect to the position of the power reception antenna201, the control unit104transmits the certain constant voltage value as the instruction value to the alternating-current power supply401. Further, the alternating-current power supply401outputs the voltage based on the instruction value while the stage502is moved from the position of 100 mm to the position of 400 mm.

In a case where the output voltage is fluctuated with respect to the position of the power reception antenna201as illustrated inFIG.3, however, the voltage applied to the motor402is fluctuated even when the alternating-current power supply401continuously outputs the constant voltage. Thus, the fluctuation amount of the output voltage while the power reception antenna201is moved from the position of 100 mm to the position of 400 mm is preliminarily measured and is stored in the control unit104in advance as base data. Then, the control unit104corrects the instruction value transmitted to the alternating-current power supply401.

More specifically, the control unit104adds a correction value to correct the fluctuation amount inFIG.3and make the voltage constant, to an original instruction value. When the control unit104performs such feedforward control, the alternating-current power supply401outputs a voltage fluctuated in a direction opposite to a fluctuation direction inFIG.3to offset the fluctuation amount while the power reception antenna201is moved from the position of 100 mm to the position of 400 mm. As a result, the control unit104can continuously apply the constant voltage value to the motor402.

Further, as described in the first exemplary embodiment, fluctuation caused by vibration of the stage502and the like is added. Thus, the control unit104also performs the feedback control on the output of the alternating-current voltage of the alternating-current power supply401based on the fluctuation of the alternating current detected by the current detection unit103. More specifically, the control unit104further adds a correction value to the instruction value based on the instantaneous value of the alternating current detected by the current detection unit103.

FIGS.4A to4Dare diagrams each illustrating a voltage waveform for description of the above-described correction. A horizontal axis indicates the time, and a vertical axis indicates the voltage value applied to the motor402.FIG.4Aillustrates a time waveform of the voltage applied to the motor402in a case where the above-described feedback control and the above-described feedforward control are not performed and the power reception antenna201on the stage502is moved from the position of 100 mm to the position of 400 mm. InFIG.4A, the fluctuation of the output voltage caused by vibration of the stage502is simulatively added as a primary curve relative to the fluctuation of the output voltage depending on the position of the power reception antenna201illustrated inFIG.3.

FIG.4Bis a diagram illustrating a voltage waveform of the correction value of the above-described feedforward control.

FIG.4Billustrates, as the correction value, a preliminarily-measured result of the fluctuation of the output voltage when the power reception antenna201on the stage502is moved from the position of 100 mm to the position of 400 mm.

FIG.4Cis a diagram illustrating a voltage waveform of the correction value of the above-described feedback control. The control unit104calculates the correction value inFIG.4Cfrom the difference between the instantaneous value of the alternating current detected by the current detection unit103and the preliminarily-measured desired current value.

FIG.4Dis a diagram illustrating a time waveform of the voltage applied to the motor402in a case where the correction is performed with the correction value of the feedforward control inFIG.4Band the correction value of the feedback control inFIG.4C. The voltage inFIG.4Dis obtained by subtracting the voltage inFIG.4Bfrom the voltage inFIG.4Aand adding the voltage inFIG.4Cto the voltage inFIG.4A. The control unit104performs the correction on the instruction value based on the correction value of the feedforward control inFIG.4Band the correction value of the feedback control inFIG.4C, which makes it possible to continuously apply the desired constant voltage as illustrated inFIG.4D, to the motor402.

The case where the constant voltage value is continuously applied to the motor402has been described fir a simplification purpose of the description; however, the correction is performed in a similar manner in a case where the voltage is not the constant voltage value and is the alternating-current voltage having various values, including a negative voltage. Further, the correction value for the feedforward control by the preliminary measurement is obtained by measuring the output voltage while the power reception antenna201is stopped at each position; however, the preliminary measurement may be performed while the power reception antenna201is moved by the actual operation sequence of the stage502. As a result, the correction value including influence by not only the fluctuation of the output voltage depending on the position of the power reception antenna201but also vibration caused by the operation of the stage502can be made, which makes it possible to reduce a correction amount in the feedback control and to control the motor402with higher accuracy.

As described above, the control unit104combines the feedforward control correcting the fluctuation of the output voltage depending on the position of the power reception antenna201with the feedback control using the alternating current detected by the current detection unit103described in the first exemplary embodiment. As a result, the control unit104can control the voltage applied to the motor (load unit)402with high accuracy based on power supplied by the wireless power transmission.

At least one of the power transmission antenna101and the power reception antenna201is movable. The control unit104controls the alternating-current voltage value applied to the switch circuit102based on the correction value corresponding to the relative position of the power reception antenna201to the power transmission antenna101inFIG.4Band the correction value corresponding to the current value detected by the current detection unit103inFIG.4C.

According to the present exemplary embodiment, the control unit104can control the alternating-current voltage applied to the motor402with high accuracy by the feedforward control and the feedback control.

Next, a control system300according to a third exemplary embodiment is described. Hereinafter, a difference between the third exemplary embodiment and each of the first and second exemplary embodiments is described.

FIG.5is a block diagram illustrating a configuration example of the control system300according to the third exemplary embodiment.

The control system300inFIG.5includes a gate driving circuit105, a clock generation circuit106, a transmission circuit107, a transmission antenna108, a gate driving circuit203, a reception circuit204, and a reception antenna205added to the control system300inFIG.1.

A power transmission unit100includes the power transmission antenna101, the switch circuit102, the current detection unit103, the control unit104, the gate driving circuit105, the clock generation circuit106, the transmission circuit107, and the transmission antenna108. A power reception unit200includes the power reception antenna201, the rectification circuit202, the gate driving circuit203, the reception circuit204, and the reception antenna205.

The clock generation circuit106generates a clock signal, and outputs the clock signal to the gate driving circuit105and the transmission circuit107. The gate driving circuit105drives the switch circuit102based on the clock signal. The transmission circuit107generates a wireless transmission signal based on the clock signal, and supplies the wireless transmission signal to the transmission antenna108. The transmission antenna108wirelessly transmits the wireless transmission signal to the reception antenna205. The wireless transmission signal is transmitted from the transmission antenna108to the reception antenna205in a contactless manner. The transmission antenna108and the reception antenna205perform wireless communication by electromagnetic field coupling, optical coupling, a radio wave, or the like.

The reception antenna205wirelessly receives the wireless transmission signal wirelessly transmitted from the transmission antenna108. The reception circuit204restores the clock signal generated by the clock generation circuit106based on the wireless transmission signal received by the reception antenna205. The gate driving circuit203drives the rectification circuit202based on the clock signal. The rectification circuit202rectifies power wirelessly received by the power reception antenna201, and restores a waveform of the alternating-current voltage supplied by the alternating-current power supply401.

Each of the switch circuit102and the rectification circuit202includes a full-bridge circuit of a bidirectional switch to receive and output an alternating-current waveform including a negative voltage. The bidirectional switch is a switch that can switch between conduction and non-conduction at a timing based on the clock signal when the voltage applied to the bidirectional switch is a positive voltage or a negative voltage. For example, the bidirectional switch may be a circuit in which sources and gates of two metal oxide semiconductor field-effect transistors (MOSFETs) are connected. When a positive voltage or a negative voltage is applied between drains of the two MOSFETs, the bidirectional switch becomes conductive only at a timing when the bidirectional switch is turned on by a gate-source voltage, and becomes non-conductive at other timings. To synchronize the switch circuit102and the rectification circuit202, the transmission circuit107transmits the clock signal as the wireless transmission signal via the transmission antenna108.

With the above-described configuration, the switch circuit102and the rectification circuit202can switch the alternating-current voltage in synchronization with each other. This enables the rectification circuit202to restore the alternating-current voltage output from the alternating-current power supply401with high accuracy. Accordingly, the rectification circuit202can control the voltage applied to the motor102with high accuracy based on power supplied by the wireless power transmission.

A power supply voltage to operate the gate driving circuit203and the reception circuit204may be generated from the voltage applied to the motor402by using a buck-boost converter the like. Further, the power transmission antenna101and the power reception antenna201may be separately provided for the power supply voltage of the gate driving circuit203and the reception circuit204.

The power transmission antenna101and the power reception antenna201may be formed by wiring on a printed circuit board. Further, a magnetic sheet may be bonded to the printed circuit board to reduce loss in electromagnetic field coupling and radiation of electromagnetic noise. Furthermore, each of the power transmission antenna101and the power reception antenna201may be a winding transformer using a magnetic body of ferrite or the like, and a winding of lite wire or the like.

As described above, the clock generation circuit106generates the clock signal. The gate driving circuit105drives the switch circuit102based on the clock signal generated by the clock generation circuit106. The transmission circuit107generates the wireless transmission signal based on the clock signal generated by the clock generation circuit106. The transmission antenna108wirelessly transmits the wireless transmission signal.

The reception antenna205wirelessly receives the wireless transmission signal wirelessly transmitted from the transmission antenna108. The reception circuit204restores the clock signal based on the signal received by the reception antenna205. The gate driving circuit203drives the rectification circuit202based on the clock signal restored by the reception circuit204.

Each of the switch circuit102and the rectification circuit202includes the bidirectional switch. The switch circuit102and the rectification circuit202are driven based on the clock signals synchronized with each other. The clock signal for the rectification circuit202is the wirelessly-transmitted clock signal of the switch circuit102.

According to the present exemplary embodiment, the control system300can control the alternating-current voltage applied to the motor402with high accuracy by synchronizing the clock signal for the switch circuit102and the clock signal for the rectification circuit202.

The above-described exemplary embodiments are merely specific examples for implementation of the present disclosure, and the technical scope of the present disclosure is not limited to these exemplary embodiments. In other words, the present disclosure can be implemented in various ways without departing from the technical concept or major characteristics of the present disclosure.

It is possible to perform the wireless power transmission on the load unit and to control the alternating-current voltage applied to the load unit with high accuracy.

While the present disclosure has described exemplary embodiments, it is to be understood that some embodiments are not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

This application claims priority to Japanese Patent Application No. 2021-111928, which was filed on Jul. 6, 2021 and which is hereby incorporated by reference herein in its entirety.