CONTROL APPARATUS AND METHOD OF CONTROLLING THE APPARATUS

A control apparatus includes a driver that outputs power based on a first control signal; a wireless power transmission system that is connected downstream of the driver, that receives first power, and that supplies second power to a motor through wireless power transmission; and a compensator that compensates a difference between a phase of the first control signal and a phase of current output from the wireless power transmission system.

BACKGROUND OF THE INVENTION

Field of the Invention

The disclosure relates to a control apparatus and a method of controlling the control apparatus.

Description of the Related Art

Systems have been proposed in which power is supplied to a linear motor to drive the liner motor. For example, in a semiconductor exposure apparatus, a motor that fine-moves reticle is installed on a reticle stage for moving the reticle to the exposure apparatus. A power supply cable for supplying the power to drive the motor is connected on the stage. Since the power supply cable moves with the movement of the stage, the tension of the cable influences the accuracy of positioning of the stage and the time required to complete the positioning. Accordingly, wireless transmission of the power for driving the motor is considered in order to improve the performance of the semiconductor exposure apparatus.

Japanese Patent Laid-Open No. 2018-54847 discloses a method of arranging a motor driver and a power receiver for wireless power transmission on a coarse-motion stage, wirelessly transmitting direct-current voltage to a power receiver on the coarse-motion stage, and applying the direct-current voltage to the motor driver on the coarse-motion stage. In the method disclosed in Japanese Patent Laid-Open No. 2018-54847, alternating current to be applied to the motor installed on the coarse-motion stage is generated to drive the motor. At this time, an instruction value signal for controlling the magnitude and the plus and minus of the alternating current output from the motor driver is transmitted in common wireless communication, such as Bluetooth (registered trademark).

SUMMARY OF THE INVENTION

A control apparatus includes a driver that outputs power based on a first control signal; a wireless power transmission system that is connected downstream of the driver, that receives first power, and that supplies second power to a motor through wireless power transmission; and a compensator that compensates a difference between a phase of the first control signal and a phase of current output from the wireless power transmission system.

DESCRIPTION OF THE EMBODIMENTS

First Embodiment

FIG.1is a diagram illustrating an example of a voltage control current source100that drives a motor104in a wired connection state. The voltage control current source100outputs arbitrary current Iin that is first-order proportional to control voltage Vc input between control voltage input lines105aand105b. The motor104is capable of being represented by a series circuit composed of a resistor102and an inductor103as an equivalent circuit. The influence of parasitic capacitance occurring in the actual machine of the motor104is ignored for simplicity of description. The voltage control current source100is connected to the motor104via lead wires101aand101b.

The voltage Vc is control voltage input between the control voltage input lines105aand105b.

The current Iin is current output from the voltage control current source100. Voltage Vin is voltage output from the voltage control current source100. Voltage Va is voltage at both ends of the resistor102. Voltage Vb is voltage at both ends of the inductor103. Current Iout is current to flow into the motor104.

Voltage Vout is voltage at both ends of the motor104.

FIG.2Ais a vector diagram indicating the phase relationship between the voltages Vc, Vin, Vout, Va, and Vb and the currents Iin and Iout. Referring toFIG.2A, the upper direction of the vertical axis represents the orientation of phase lead and the lower direction of the vertical axis represents the orientation of phase lag.

In the configuration illustrated inFIG.1, the voltage control current source100is connected to the motor104via the lead wires101aand101b. Accordingly, the current Iin output from the voltage control current source100is the same as the current Iout to flow into the motor104. Consequently, the direction of the vector of the current Iin coincides with the direction of the vector of the current Iout, as illustrated inFIG.2A. In other words, the phase difference between the current Iin and the current Iout is zero.

Attention is given to the phase difference in voltage between the respective components here. Since the vector of the voltage Va with respect to the vector of the current Iout indicates a voltage drop occurring at the resistor102, the direction of the vector of the voltage Va coincides with the direction of the vector of the current Iout. In other words, the voltage Va has no lead and no lag with respect to the current Iout. In contrast, the vector of the voltage Vb advances by90degrees with respect to the vector of the current Iout due to the influence of reactance of the inductor103. The vector of the voltage Vout, which is represented as combination of the vector of the voltage Va and the vector of the voltage Vb, advances with respect to the vector of the current Iout. In reverse representation of the reference of the voltage and the current, the vector of the current Iout is delayed with respect to the vector of the voltage Vout.

FIG.2Bis a graph indicating the phase difference between the current Iin output from the voltage control current source100and the current Iout to flow into the motor104in a frequency domain. Since the current Iin output from the voltage control current source100is the same as the current Iout to flow into the motor104, no phase difference occurs. Accordingly, as illustrated inFIG.2B, the phase difference between the current Iin output from the voltage control current source100and the current Iout to flow into the motor104is zero at all frequencies.

Consequently, in the configuration illustrated inFIG.1, varying the amplitude or the phase of the control voltage Vc enables the current Iin output from the voltage control current source100to be varied to control the current Iout to flow into the motor104. At this time, the phase difference between the current Iin output from the voltage control current source100and the current Iout to flow into the motor104is constantly zero (also viewed in the frequency domain). A control apparatus that drives the motor with current output from a wireless power transmission system will now be described.

FIG.3is a diagram illustrating an example of the configuration of a wireless power transmission system200according to a first embodiment.

The wireless power transmission system200includes a power transmitter202, a power transmitter antenna203, a power receiver antenna204, and a power receiver205. Lead wires201aand201bare paths through which power is supplied to the wireless power transmission system200. Lead wires206aand206bare paths through which power output from the wireless power transmission system200is supplied to the motor. The power transmitter202switches the power supplied through the lead wires201aand201band feeds the switched power to the power transmitter antenna203. The power transmitter antenna203and the power receiver antenna204are arranged so as to be apart from each other by a distance achieving significant coupling with an electromagnetic field. The power receiver antenna204supplies part of electromagnetic field energy generated by the power transmitter antenna203to the power receiver205. The power receiver205smooths the power supplied from the power receiver antenna204. In the description of the first embodiment, the power transmission efficiency of the wireless power transmission system200is not argued. The advantages of the first embodiment are produced regardless of the power transmission efficiency. It is assumed that the wireless power transmission system200performs a liner operation. In other words, the power supplied through the lead wires201aand201bhas linear relationship with the power output through the lead wires206aand206b.

FIG.4is a diagram illustrating an example of the specific configuration of the wireless power transmission system200. The wireless power transmission system200receives positive or negative voltage from a positive and negative power supply207and supplies the positive or negative voltage to the motor104. The motor104is an example of a load. The wireless power transmission system200includes the power transmitter202, the power transmitter antenna203, the power receiver antenna204, the power receiver205, a gate drive circuit208, a matching circuit209, a matching circuit210, and a gate drive circuit211.

The power transmitter202includes four bi-directional switches213. In each of the bi-directional switches213, the sources of two field effect transistors (FETs) are connected to each other and the gates of the two FETs are connected to each other. The bi-directional switch213is driven with the same gate drive signal that operates based on source potential. The gate drive circuit208supplies the gate drive signal to each of the four bi-directional switches213.

The power receiver205includes four bi-directional switches214. In each of the bi-directional switches214, the sources of two field effect transistors (FETs) are connected to each other and the gates of the two FETs are connected to each other. The bi-directional switch214is driven with the same gate drive signal that operates based on the source potential. The gate drive circuit211supplies the gate drive signal to each of the four bi-directional switches214.

The positive and negative power supply207outputs positive or negative direct-current voltage. The amplitude of the voltage output from the positive and negative power supply207determines thrust of the motor104. The positive or negative sign of the voltage output from the positive and negative power supply207determines the orientation in which the motor104moves.

The gate drive circuit208supplies the gate drive signal of a predetermined frequency to the four bi-directional switches213. The four bi-directional switches213switch the direct-current voltage output from the positive and negative power supply207in synchronization with the gate drive signal to convert the direct-current voltage output from the positive and negative power supply207into alternating-current voltage. The four bi-directional switches213apply the alternating-current voltage to the power transmitter antenna203via the matching circuit209. The power transmitter antenna203generates the electromagnetic field energy and wirelessly transmits the power to the power receiver antenna204. For example, the matching circuit209is a capacitor and the power transmitter antenna203is a coil. The matching circuit209and the power transmitter antenna203serve as a resonant circuit that resonates at the same frequency as that of the bi-directional switches213.

The power receiver antenna204supplies part of the electromagnetic field energy generated by the power transmitter antenna203to the power receiver205via the matching circuit210. For example, the power receiver antenna204is a coil and the matching circuit210is a capacitor. The power receiver antenna204and the matching circuit210serve as a resonant circuit that resonates at the same frequency as that of the bi-directional switches213.

The power receiver205is a full-bridge synchronous rectifier using the bi-directional switches214that perform the switching at the same frequency as that of the bi-directional switches213and is adjusted so as to perform the switching in the phase producing the highest power reception efficiency. The power receiver205converts the alternating-current voltage supplied from the power receiver antenna204into the direct-current voltage and supplies the direct-current voltage to the motor104.

FIG.5is a graph indicating the relationship between the voltage input into the wireless power transmission system200inFIG.4and the voltage output from the wireless power transmission system200inFIG.4. The voltage input into the wireless power transmission system200is the same as the voltage output from the positive and negative power supply207. The voltage input into the wireless power transmission system200is the same as the voltage input into the motor104. The voltage input into the wireless power transmission system200and the voltage output from the wireless power transmission system200have positive first-order linear relationship. The input-output relationship illustrated inFIG.5is established in a case in which the gate drive signals output from the gate drive circuit208and the gate drive circuit211are in a synchronized state and the phase difference between the gate drive signals output from the gate drive circuit208and the gate drive circuit211is appropriately adjusted.

The wireless power transmission system200illustrated inFIG.4is capable of performing wireless power transmission of the negative voltage. A general wireless power transmission system that does not use the bi-directional switches213and214is not capable of performing the wireless power transmission of the negative voltage. This is because, upon input of the negative voltage, a body diode of the FET (or a parasitic element corresponding to the body diode) is made conductive and the FET is in a conductive state regardless of the state of the gate drive signal, thus causing an uncontrollable state.

Since the wireless power transmission system200illustrated inFIG.4is capable of performing the wireless power transmission of the negative voltage, for example, it is possible to perform direct wireless power transmission of driving power of the motor104. Specifically, in a normal rotation operation and a reverse rotation operation of the motor104inFIG.1, the current value to flow into the motor104is capable of being output from the voltage control current source100and the power output from the voltage control current source100is capable of being subjected to the wireless power transmission by the wireless power transmission system200illustrated inFIG.4. In other words, the positive and negative power supply207inFIG.4corresponds to the voltage control current source100inFIG.1. At this time, the control voltage corresponding to the current value to flow into the motor104is input into the voltage control current source100as the control voltage Vc.

FIG.6is a diagram illustrating a configuration in which the wireless power transmission system200inFIG.4performs the wireless power transmission of the power output from the voltage control current source100inFIG.1. The wireless power transmission system200inFIG.4is provided between the voltage control current source100and the motor104in the configuration inFIG.6, unlike the configuration inFIG.1. The wireless power transmission system200wirelessly transmits the power output from the voltage control current source100and supplies the power to the motor104.

The voltage control current source100is connected to the wireless power transmission system200via the lead wires201aand201b. The wireless power transmission system200is connected to the motor104via the lead wires206aand206b.

The current Iin is current output from the voltage control current source100. The voltage Vin is voltage input between the lead wires201aand201b. The voltage Vout is voltage between the lead wires206aand206b. The current Iout is current to flow into the motor104.

In the actual wireless power transmission system, time delay corresponding to several tens of periods of a switching frequency of the power transmitter202may occur between the voltage Vin and the voltage Vout. However, the switching frequency of the power transmitter202is generally about several tens of times to about one thousand of times higher than a control frequency of the motor104. For example, the control frequency of the motor104is about 10 kHz while a frequency of 100 kHz to 15,000 kHz is selected as the switching frequency of the power transmitter202. In the light of the above precondition, the delay between the voltage Vin and the voltage Vout, which is caused by the wireless power transmission system200inFIG.6, is capable of being ignored in the first embodiment. The advantages of the first embodiment are not phenomena specifically produced with this precondition. This precondition is within an extremely reasonable range in a logical description of the first embodiment. In addition, there are cases in which the time delay occurring between the voltage Vin and the voltage Vout is too long to ignore with respect to the control frequency of the motor104. In such a case, a mode may be applicable in which the time delay (the phase difference) occurring between the voltage Vin and the voltage Vout is included in an amount of phase compensation of phase compensators300and400described below.

The relationship between the current Iin output from the voltage control current source100and the current Iout to flow into the motor104when the configuration inFIG.6is used will now be considered. In the voltage control current source100in which the motor104is driven in the wired connection state inFIG.1, the phase difference between the current Iin output from the voltage control current source100and the current Iout to flow into the motor104is zero, as indicated inFIG.2A. When the motor104is to be controlled, the state in which the phase difference between the current Iin output from the voltage control current source100and the current Iout to flow into the motor104is zero is considered to be most appropriate.

The phase relationship between the current Iin output from the voltage control current source100and the voltage Vout to flow into the motor104will now be described with reference toFIG.7AandFIG.7B.FIG.7Ais a vector diagram indicating the phase relationship between the voltages Vc, Vin, Vout, Va, and Vb and the currents Iin and Iout inFIG.6. Referring toFIG.7A, the upper direction of the vertical axis represents the orientation of the phase lead and the lower direction of the vertical axis represents the orientation of the phase lag.

The phase of the control voltage Vc input into the voltage control current source100coincides with the phase of the current Iin output from the voltage control current source100, as described above. Accordingly, the direction of the vector of the control voltage Vc coincides with the direction of the vector of the current Iin. Input impedance of the wireless power transmission system200is capable of being considered as actual resistance when viewed from an output terminal of the voltage control current source100. This is because the switching frequency of the power transmitter202is generally about several tens of times to about one thousand of times higher than the control frequency of the motor104and a smoothing effect of a decoupling capacitor connected to a power supply input terminal of the wireless power transmission system200exists. Accordingly, little influence of the switching of the power transmitter202is exerted on the output terminal of the voltage control current source100. The decoupling capacitor is constantly connected in a general designing method.

Consequently, the input impedance of the wireless power transmission system200is hereinafter considered as the actual resistance. In this case, the voltage input into the wireless power transmission system200(the voltage output from the voltage control current source100) Vin is proportional to the current Iin output from the voltage control current source100. In other words, the direction of the vector of the voltage Vin coincides with the direction of the vector of the current Iin. As assumed in the manner described above, since the wireless power transmission system200immediately outputs the voltage Vin input between the lead wires201aand201bas the voltage Vout between the lead wires206aand206b, the direction of the vector of the voltage Vin coincides with the direction of the vector of the voltage Vout. Since the phase relationship between the vector of the voltage Vout and the vector of the current Iout is the same as the relationship described above with reference toFIG.2A, a description of the phase relationship between the vector of the voltage Vout and the vector of the current Iout is omitted herein. In conclusion, the current Iout is delayed with respect to the vector of the voltage Vout (≈Vin). Since the direction of the vector of the voltage Vin coincides with the direction of the vector of the current Iin, the vector of the current Iout is delayed with respect to the vector of the current Iin.

Referring toFIG.7A, a phase difference θ is the phase difference (an amount of lag) of the current Iout with respect to the current Iin. The phase difference θ is represented by Expression (1). In Expression (1), ω denotes an angular frequency of the control voltage Vc, L denotes the inductance of the inductor103, and R denotes the resistance value of the resistor102.

FIG.7Bis a graph in which the phase difference is represented in the frequency domain. The phase difference between the current Iin output from the voltage control current source100and the current Iout to flow into the motor104is zero for all frequencies inFIG.2B. In contrast, the absolute value of the phase difference (the amount of lag) θ is monotonically increased with the increasing frequency inFIG.7B. In the configuration inFIG.6, the property in which the absolute value of the phase difference θ is monotonically increased with the increasing frequency, as inFIG.7B, is not desirable. For example, when the driving of the motor104is to be started at the angular frequency ω at a time 0, it is assumed that the control voltage Vc at the angular frequency ω is input into the voltage control current source100at the time 0. In such a case, the motor104starts to operate at a time d delayed by the time corresponding to the phase difference θ represented by Expression (1). The time d is represented by Expression (2):

Ideally, the phase difference between the current Iin output from the voltage control current source100and the current Iout to flow into the motor104is zero for all frequencies, as indicated inFIG.2B. However, when the motor104is driven with the power output from the wireless power transmission system200in the configuration inFIG.6, the timing (the phase) at which the motor104operates is delayed with respect to the control voltage Vc. In addition, the amount of lag is monotonically increased with the increasing frequency.

This is the problem to be resolved in the first embodiment. Specifically, the problem in the first embodiment is the difference that occurs between the phase of the current Iin input into the wireless power transmission system200and the phase of the current Iout output from the wireless power transmission system200, which is caused by the electrical property of the wireless power transmission system200. In order to resolve the above problem, the phase compensator is adopted.

FIG.8is a diagram illustrating the phase compensator300according to the first embodiment. Lead wires301aand301bare connected to an input portion of the phase compensator300. Lead wires302aand302bare connected to an output portion of the phase compensator300. The current Iin is current input into the phase compensator300through the lead wires301aand301b. The voltage Vin is voltage input between the lead wires301aand301b. Voltage V2out is voltage output between the lead wires302aand302bby the phase compensator300. Current I2out is current output from the phase compensator300to the lead wires302aand302b. The phase compensator300is described to operate as an electric circuit. The phase compensator300may be installed as software using digital operations. Similarly, the phase compensator300may be installed as a logic circuit using a field programmable gate array (FPGA). Put another way, the phase compensator may be realized through a digital implementation or an analogue implementation or a combination of a digital and analogue.

FIG.9is a vector diagram for describing the advantages of phase compensation by the phase compensator300inFIG.8. Referring toFIG.9, the upper direction of the vertical axis represents the orientation of the phase lead. In contrast, the lower direction of the vertical axis represents the orientation of the phase lag. The phase compensator300functions so as to advance the voltage V2out by an amount of phase compensation φ with reference to the voltage Vin input between the lead wires301aand301b. In the electric circuit, the phase compensator300varies a power factor by the amount of phase compensation cp. In other words, the vector of the voltage V2out output between the lead wires302aand302bis oriented to a direction that advances by the angle φ with respect to the vector of the voltage Vin input between the lead wires301aand301binFIG.9. In contrast, the vector of the current I2out output from the phase compensator300is oriented to the same direction as that of the vector of the voltage Vin input between the lead wires301aand301b. How to resolve the above problem using the phase compensator300described above with reference toFIG.8andFIG.9will be described.

FIG.10is a diagram illustrating an example of the configuration of a control apparatus310according to the first embodiment. The control apparatus310includes the voltage control current source100, the phase compensator300, the wireless power transmission system200, and the motor104. A method of controlling the control apparatus310will now be described.

The voltage control current source100outputs arbitrary current Iin first-order proportional to the control voltage Vc input between the control voltage input lines105aand105b. The voltage control current source100is connected to the phase compensator300via the lead wires301aand301b. The current Iin is current output from the voltage control current source100. The voltage Vin is voltage input between the lead wires301aand301b. The phase of the current Iin coincides with the phase of the voltage Vin, as indicated inFIG.9.

The phase compensator300outputs the voltage V2out resulting from compensation of the phase of the voltage Vin. The voltage V2out is voltage the phase of which advances by the amount of phase compensation φ with respect to the voltage Vin, as illustrated inFIG.9. The phase compensator300is connected to the wireless power transmission system200via the lead wires302aand302b. The voltage V2out is voltage output between the lead wires302aand302bby the phase compensator300. The current I2out is current output from the phase compensator300. The phase of the current I2out coincides with the phase of the current Iin, as indicated inFIG.9.

The wireless power transmission system200receives the power of the voltage V2out, wirelessly transmits the power, and outputs the power of the voltage Vout. The wireless power transmission system200is connected to the motor104via the lead wires206aand206b. The voltage Vout is voltage output between the lead wires206aand206bby the wireless power transmission system200. The current Iout is current output from the wireless power transmission system200to the motor104. The motor104is capable of being represented by a series circuit composed of the resistor102and the inductor103. The voltage Va is voltage at both ends of the resistor102. The voltage Vb is voltage at both ends of the inductor103.

The phase relationship between the current Iin output from the voltage control current source100inFIG.10and the current Iout to flow into the motor104will now be described with reference toFIG.11.FIG.11is a vector diagram indicating the phase relationship between the voltages Vc, Vin, V2out, Vout, Va, and Vb and the currents Iin, I2out and Iout inFIG.10. Referring toFIG.11, the upper direction of the vertical axis represents the orientation of the phase lead and the lower direction of the vertical axis represents the orientation of the phase lag.

The phase of the control voltage Vc input into the voltage control current source100, the phase of the voltage Vin output from the voltage control current source100, and the phase of the current Iin output from the voltage control current source100coincide with each other, as described above. Accordingly, the direction of the vector of the control voltage Vc, the direction of the vector of the voltage Vin, and the direction of the vector of the current Iin coincide with each other.

Referring toFIG.9, the phase difference φ in the phase lead direction occurs between the voltage Vin input into the phase compensator300and the voltage V2out output from the phase compensator300. Accordingly, the vector of the voltage V2out is oriented to a direction that advances with respect to the vector of the voltage Vin by the angle φ inFIG.11.

The phase of the current Iin input into the phase compensator300coincides with the phase of the current I2out output from the phase compensator300, and the linear relationship is established between the phase of the current Iin input into the phase compensator300and the phase of the current I2out output from the phase compensator300. Accordingly, the direction of the vector of the current Iin coincides with the direction of the vector of the current I2out.

The linear relationship is established between the voltage V2out input into the wireless power transmission system200and the voltage Vout output from the wireless power transmission system200. In other words, the direction of the vector of the voltage V2out coincides with the direction of the vector of the voltage Vout. Since the wireless power transmission system200immediately outputs the voltage V2out input between the lead wires302aand302bas the voltage Vout between the lead wires206aand206b, as described above, the direction of the vector of the voltage V2out coincides with the direction of the vector of the voltage Vout.

The phase relationship between the voltages Vout, Va, and Vb and the current Iout is the same as the relationship described above with reference toFIG.7A. Specifically, since the vector of the voltage Va with respect to the vector of the current Iout indicates a voltage drop occurring at the resistor102, the direction of the vector of the voltage Va coincides with the direction of the vector of the current Iout. In other words, the voltage Va has no lead and no lag with respect to the current Iout. In contrast, the vector of the voltage Vb advances by 90 degrees with respect to the vector of the current Iout due to the influence of the reactance of the inductor103. The vector of the voltage Vout, which is represented as combination of the vector of the voltage Va and the vector of the voltage Vb, advances by the phase difference θ with respect to the vector of the current Iout. In reverse representation of the reference of the voltage and the current, the vector of the current Iout is delayed with respect to the vector of the voltage Vout by the phase difference θ. The phase difference θ is represented by Expression (1). The vector diagram when the relationship according to Expression (3) is established is indicated inFIG.11.

In this case, a phase difference (an amount of lag) δ occurs between the current Iin output from the voltage control current source100and the current Iout to flow into the motor104, as represented by Expression (4):

How to minimize the phase difference δ between the current Iin output from the voltage control current source100and the current Iout to flow into the motor104will now be considered. As apparent from Expression (4), the phase difference δ and the amount of phase compensation φ are to be adjusted so as to be substantially equal to each other. In other words, it is possible to minimize the phase difference δ between the current Iin output from the voltage control current source100and the current Iout to flow into the motor104by adjusting the amount of phase compensation φ of the phase compensator300so as to establish Expression (5):

At this time, Expression (6) is established and the phase difference δ is approximately zero.

In sum, when the motor104is driven with the power output from the wireless power transmission system200in the configuration illustrated inFIG.10, the amount of phase compensation φ of the phase compensator300is adjusted so as to meet Expression (5). This minimizes the phase difference δ between the control voltage Vc and the current Iout to flow into the motor104to suppress a delay of the timing (phase) at which the motor104operates with respect to the control voltage Vc.

As described above, the problem of the first embodiment is the difference occurring between the phase of the control voltage Vc and the phase of the current Iout for driving the motor104. According to the first embodiment, the control apparatus310is capable of resolving the above problem by adopting the phase compensator300having the appropriate amount of phase compensation φ so as to meet Expression (5).

As described above, the voltage control current source100is an example of a linear motor driver506illustrated inFIG.22AandFIG.22Band outputs the power based on the control voltage Vc. The control voltage Vc is an example of a control signal. The wireless power transmission system200is connected downstream of the voltage control current source100. The wireless power transmission system200receives first power and supplies second power to the motor104through the wireless power transmission. The phase compensator300is a compensator and compensates the difference between the phase of the control voltage Vc and the phase of the current Iout output from the wireless power transmission system200.

As indicated inFIG.11, the phase of the current Iout output from the wireless power transmission system200is delayed with respect to the phase of the voltage Vout output from the wireless power transmission system200. The phase compensator300is provided between the voltage control current source100and the wireless power transmission system200. The phase compensator300receives the power output from the voltage control current source100, and supplies the first power, in which the phase of the voltage V2out input into the wireless power transmission system200advances with respect to the phase of the voltage Vin output from the voltage control current source100, to the wireless power transmission system200.

As illustrated inFIG.4, the wireless power transmission system200includes the power transmitter antenna203, the power receiver antenna204, the power transmitter202, and the power receiver205. The power transmitter antenna203is an antenna for the wireless power transmission. The power receiver antenna204wirelessly receives the power of the power transmitter antenna203. The power transmitter202is a switch circuit. The power transmitter202switches the input power based on a first switching signal from the gate drive circuit208and applies the voltage to the power transmitter antenna203. The power receiver205is a rectifier circuit. The power receiver205rectifies the voltage output from the power receiver antenna204based on a second switching signal from the gate drive circuit211and applies the rectified voltage to the motor104. The power transmitter202includes the multiple bi-directional switches213. The power receiver205includes the multiple bi-directional switches214.

The first switching signal has the same period as that of the second switching signal. The bi-directional switches213in the power transmitter202are driven with the first switching signal based on the potential of source terminals of the bi-directional switches213. The bi-directional switches214in the power receiver205are driven with the second switching signal based on the potential of source terminals of the bi-directional switches214.

As described above, according to the first embodiment, the control apparatus310drives the motor104with the current Iout output from the wireless power transmission system200. The phase compensator300compensates the difference occurring between the phase of the control voltage Vc input into the control apparatus310and the phase of the current Iout for driving the motor104, which is output from the wireless power transmission system200, due to the electrical property of the wireless power transmission system200. Reducing the difference by the phase compensator300enables a control speed and a control accuracy of the motor104to be improved.

Second Embodiment

FIG.12is a diagram illustrating an example of the configuration of a control apparatus410according to a second embodiment. The control apparatus410includes a phase compensator400, the voltage control current source100, the wireless power transmission system200, and the motor104. The phase compensator400is provided upstream of the voltage control current source100and has the same function as that of the phase compensator300of the first embodiment.

Lead wires401aand401bare connected to an input portion of the phase compensator400. The phase compensator400is connected to the voltage control current source100via lead wires402aand402b. The phase compensator400receives control voltage Vc1between the lead wires401aand401b, performs the phase compensation of the amount of phase compensation gyp, and outputs control voltage Vc2between the lead wires402aand402b. The control voltage Vc2is voltage resulting from advancing the phase of the control voltage Vc1by the amount of phase compensation φ.

The voltage control current source100outputs arbitrary current Iin first-order proportional to the control voltage Vc2input between the lead wires402aand402b. The voltage control current source100is connected to the wireless power transmission system200via the lead wires201aand201b. The current Iin is current output from the voltage control current source100. The voltage Vin is voltage output between the lead wires201aand201bby the voltage control current source100.

The wireless power transmission system200receives the power of the voltage Vin, wirelessly transmits the power, and outputs the power of the voltage Vout. The wireless power transmission system200is connected to the motor104via the lead wires206aand206b. The voltage Vout is voltage output between the lead wires206aand206bby the wireless power transmission system200. The current Iout is current output from the wireless power transmission system200to the motor104. The motor104is capable of being represented by a series circuit composed of the resistor102and the inductor103. The voltage Va is voltage at both ends of the resistor102. The voltage Vb is voltage at both ends of the inductor103.

FIG.13Ais a vector diagram for describing the advantages of phase compensation by the phase compensator400. The phase compensator400functions so as to advance the control voltage Vc2by the amount of phase compensation φ with reference to the control voltage Vc1. Accordingly, the vector of the control voltage Vc2is oriented to a direction the phase of which advances by the amount of phase compensation φ with respect to the vector of the control voltage Vc1. In the second embodiment, the amount of phase compensation φ meets Expression (5) described above.

The phase relationship between the control voltage Vc1and the current Iout to flow into the motor104will now be described with reference toFIG.13B.FIG.13Bis a vector diagram indicating the phase relationship between the voltages Vc1, Vc2, Vin, Vout, Va, and Vb and the currents Iin and Iout. Referring toFIG.13AandFIG.13B, the upper direction of the vertical axis represents the orientation of the phase lead and the lower direction of the vertical axis represents the orientation of the phase lag.

As described above with reference toFIG.13A, the phase difference of the amount of phase compensation φ exists between the control voltage Vc1and the control voltage Vc2. Accordingly, the vector of the control voltage Vc2is oriented to a direction the phase of which advances by the amount of phase compensation φ with respect to the vector of the control voltage Vc1.

The phase of the control voltage Vc2input into the voltage control current source100, the phase of the voltage Vin output from the voltage control current source100, and the phase of the current Iin output from the voltage control current source100coincide with each other, as described above. Accordingly, the direction of the vector of the control voltage Vc2, the direction of the vector of the voltage Vin, and the direction of the vector of the current Iin coincide with each other.

The linear relationship is established between the voltage Vin input into the wireless power transmission system200and the voltage Vout output from the wireless power transmission system200. In other words, the direction of the vector of the voltage Vin coincides with the direction of the vector of the voltage Vout. Since the wireless power transmission system200immediately outputs the voltage Vin input between the lead wires201aand201bas the voltage Vout between the lead wires206aand206b, as assumed above, the direction of the vector of the voltage Vin coincides with the direction of the vector of the voltage Vout.

The phase relationship between the voltages Vout, Va, and Vb and the current Iout is the same as the relationship described above with reference toFIG.7A. Specifically, since the vector of the voltage Va with respect to the vector of the current Iout indicates a voltage drop occurring at the resistor102, the direction of the vector of the voltage Va coincides with the direction of the vector of the current Iout. In other words, the voltage Va has no lead and no lag with respect to the current Iout. In contrast, the vector of the voltage Vb advances by 90 degrees with respect to the vector of the current Iout due to the influence of the reactance of the inductor103. The vector of the voltage Vout, which is represented as combination of the vector of the voltage Va and the vector of the voltage Vb, advances by the phase difference θ with respect to the vector of the current Iout. In reverse representation of the reference of the voltage and the current, the vector of the current Iout is delayed with respect to the vector of the voltage Vout by the phase difference θ. The phase difference θ is represented by Expression (1) indicated above. Since the amount of phase compensation φ meets Expression (5) described above, the phase difference occurring between the control voltage Vc1and the current Iout to flow into the motor104is approximately zero.

As described above, according to the second embodiment, the control apparatus410has the advantage of reducing the phase difference between the phase of the control voltage Vc1and the phase of the current Iout for driving the motor104, as in the first embodiment. Two configuration examples will now be described as specific examples of the configuration of the phase compensator400.

FIG.14is a diagram illustrating an example of the configuration of the phase compensator400composed of an analog circuit using an operational amplifier Ul. The phase compensator400includes the operational amplifier U1, resistors R1to R4, and capacitors C1and C2and has a configuration based on a non-inverting amplifier circuit. For example, the resistor R1has a resistance of 300 Ω, the resistor R2has a resistance of 10 kΩ, the resistor R3has a resistance of 400 Ω, and the resistor R4has a resistance of 1.2 kΩ. The capacitor C1has a capacitance of 0.2 g and the capacitor C2has a capacitance of 0.3 μF. The phase compensator400receives the control voltage Vc1based on ground potential and gains the control voltage Vc2based on the ground potential.

FIG.15AandFIG.15Bare graphs indicating transmission characteristics of the phase compensator400inFIG.14.

Referring toFIG.15A, the horizontal axis represents frequency and the vertical axis represents the ratio in amplitude (power) of the control voltage Vc2to the control voltage Vc1in units of dB. Referring toFIG.15B, the horizontal axis represents frequency and the vertical axis represents the phase difference between the control voltage Vc1and the control voltage Vc2in units of degrees.

Attention has mainly been given to the phase relationship between the control voltage Vc1and the current Iout to flow into the motor104in the above description. In contrast, the amplitude relationship between the control voltage Vc1and the current Iout to flow into the motor104is not considered so much. Since the phase difference between the control voltage Vc1and the current Iout to flow into the motor104generally has a higher impact on the performance, the second embodiment concentrates on improvement of the phase relationship.

However, when the wireless power transmission system200is used, the application of the wireless power transmission system200has no small influence on the amplitude relationship. Accordingly, varying the amplitude relationship between the control voltage Vc1and the current Iout to flow into the motor104at each frequency with the phase compensator300or the phase compensator400, like the amplitude characteristic illustrated inFIG.15A, is not denied in the second embodiment. The use of the phase compensator300or the phase compensator400enables the improvement effect of the control apparatus310or410to which the wireless power transmission system200is applied to be enforced.

FIG.16is a diagram illustrating an example of the configuration of the phase compensator400using an infinite impulse response (IIR) digital filter. The phase compensator400receives the control voltage Vc1and outputs the control voltage Vc2. This digital filter may be installed as software using digital operations. Similarly, this digital filter may be installed as a logic circuit using the FPGA.

Weighting coefficients a1, a2, b0, b1, and b2 inFIG.16are weighting coefficients for the IIR digital filter. For example, a1−−1.001815, a2=0.198548, b0=1.908796, b1−−2.090536, and b2=0.401394. The values of the weighting coefficients a1, a2, b0, b1, and b2 are derived through Z conversion using bilinear transform for the phase compensator400composed of the analog circuit using the operational amplifier U1illustrated inFIG.14. Accordingly, when the values of the weighting coefficients a1, a2, b0, b1, and b2 are used in the IIR digital filter illustrated inFIG.16, the transmission characteristics of the IIR digital filter illustrated inFIG.16are substantially equivalent to those inFIG.15AandFIG.15B.

The two specific configuration examples of the phase compensator400are described above. As apparent from these examples, the phase compensator300and the phase compensator400adopted in the first embodiment and the second embodiment, respectively, are capable of being practically realized and installed. Results of measurement of the advantages of the phase compensator300and the phase compensator400in the actual machine of the control apparatus to which the wireless power transmission system200is applied will be described in a third embodiment.

As described above, the voltage control current source100outputs the power based on the control voltages Vc1and Vc2. Each of the control voltages Vc1and Vc2is an example of the control signal. The wireless power transmission system200is connected downstream of the voltage control current source100. The wireless power transmission system200receives the first power and supplies the second power to the motor104through the wireless power transmission. The phase compensator400is a compensator and compensates the difference between the phase of the control voltage Vc1and the phase of the current Iout output from the wireless power transmission system200.

The phase of the current Iout output from the wireless power transmission system200is delayed with respect to the phase of the voltage Vout output from the wireless power transmission system200, as illustrated inFIG.13B. The voltage control current source100receives the control voltage Vc2. The phase compensator400is provided upstream of the voltage control current source100. The phase compensator400receives the control voltage Vc1and supplies the control voltage Vc2the phase of which advances with respect to the phase of the control voltage Vc1to the voltage control current source100.

The phase compensator400may compensate the difference between the phase of the control voltage Vc1and the phase of the current Iout output from the wireless power transmission system200and the difference between the amplitude of the control voltage Vc1and the amplitude of the current Iout output from the wireless power transmission system200.

Similarly, the phase compensator300inFIG.10may compensate the difference between the phase of the control voltage Vc and the phase of the current Iout output from the wireless power transmission system200and the difference between the amplitude of the control voltage Vc and the amplitude of the current Iout output from the wireless power transmission system200.

The phase compensators300and400may be composed of the analog circuits, such as the one illustrated inFIG.14. In addition, the phase compensators300and400may compensate the difference in phase using the digital operations illustrated inFIG.16. The digital operations include both arithmetic processing of programs by a digital signal processor (DSP) or a personal computer and parallel arithmetic processing by a digital circuit using the FPGA.

The transmission characteristics of the phase compensators300and400are transmission characteristics that offset the phase difference between the current input into the wireless power transmission system200and the current output from the wireless power transmission system200. The transmission characteristics of the phase compensators300and400may be transmission characteristics that offset the phase difference between the voltage input into the wireless power transmission system200and the current output from the wireless power transmission system200.

As described above, according to the second embodiment, the control apparatus410drives the motor104with the current Iout output from the wireless power transmission system200. The phase compensator400compensates the difference occurring between the phase of the control voltage Vc1input into the control apparatus410and the phase of the current Iout for driving the motor104, which is output from the wireless power transmission system200, due to the electrical property of the wireless power transmission system200. Reducing the difference by the phase compensator400enables the control speed and the control accuracy of the motor104to be improved.

Third Embodiment

The advantages of applying the phase compensator300or400in a positioning stage having the wireless power transmission system200installed thereon will now be described.

FIG.17is a top view illustrating an example of the configuration of the positioning stage using a wireless power transmission system507for power supply to a linear motor. A stage on which reticle of a semiconductor exposure apparatus is installed is exemplified in the third embodiment. The positioning stage in the third embodiment includes a coarse-motion stage501having a large stroke and a fine-motion stage503having a high positioning accuracy.

A pair of needles502aare provided at left and right sides of the driving direction (the Y-axis direction) of the coarse-motion stage501. The pair of needles502aare driven in the Y-axis direction in cooperation with the corresponding pair of stators502b. A reflecting mirror (not illustrated) is provided on the coarse-motion stage501. Measured light from a laser interferometer (a measurer) (not illustrated) is reflected by the reflecting minor to measure the amount of displacement or the position to the Y-axis direction of the stage.

The fine-motion stage503is connected to the coarse-motion stage501with a fine-motion linear motor504in a non-contact manner to be driven in the Y-axis direction with the coarse-motion stage501. In addition, the fine-motion stage503is connected to the coarse-motion stage501also in the X-axis direction with the fine-motion linear motor504in a non-contact manner to be driven in the X-axis direction. A reflecting minor (not illustrated) is provided on the fine-motion stage503. Measured light from a laser interferometer (a measurer) (not illustrated) is reflected by the reflecting mirror to measure the amounts of displacement or the positions to the X-axis direction and the Y-axis direction of the stage. The power to drive the fine-motion linear motor504is supplied from the linear motor driver506. The power supplied from the linear motor driver506is transmitted to the fine-motion linear motor504via a power transmitter507band a power receiver507aof the wireless power transmission system507and fine-motion linear motor cables505.

The power transmitter507bof the wireless power transmission system507detects current output from the linear motor driver506and transmits the power to the power receiver507avia the power transmitter antenna. The power receiver507areceives the power transmitted from the power transmitter507bvia the power receiver antenna and supplies the power to the fine-motion linear motor504via the rectifier circuit.

A control apparatus600for a position feedback control system of the fine-motion stage503with the fine-motion linear motor504will now be described with reference toFIG.18.FIG.18is a diagram illustrating an example of the configuration of the control apparatus600when the phase compensator is not provided. The control apparatus600includes a subtracter605, a compensator604, the linear motor driver506, the wireless power transmission system507, the fine-motion linear motor504, the fine-motion stage503, and a position measurer603. The linear motor driver506corresponds to the voltage control current source100inFIG.10orFIG.12. The wireless power transmission system507corresponds to the wireless power transmission system200inFIG.10orFIG.12. The fine-motion linear motor504corresponds to the motor104inFIG.10orFIG.12.

The position of the fine-motion stage503is measured by the position measurer603, such as a laser interferometer, and the measured position of the fine-motion stage503is supplied to the subtracter605. The subtracter605supplies the difference (deviation) between the position of the fine-motion stage503, which is measured by the position measurer603, and a position instruction value (a target position) to the compensator604. The compensator604includes, for example, a proportional-integral-derivative (PID) controller601. The compensator604generates a driver instruction value for the linear motor driver506based on the deviation supplied from the subtracter605. The linear motor driver506outputs the motor drive current based on the driver instruction value from the compensator604. The motor drive current output from the linear motor driver506is received by the wireless power transmission system507and is supplied to the fine-motion linear motor504via a wireless antenna and the rectifier circuit. The fine-motion linear motor504applies the thrust to the fine-motion stage503in accordance with the supplied motor drive current.

FIG.19is a graph indicating closed loop phase characteristics of the position feedback control system in the X-axis direction of the fine-motion stage503when the power transmission is performed using the wireless power transmission system507and when the power transmission is performed using a wired manner (for example, using cables). Referring toFIG.19, a solid line indicates the closed loop phase characteristic in the power transmission in the wired manner and a broke line indicates the closed loop phase characteristic in the power transmission using the wireless power transmission system507. Comparison between the phase characteristic in the wired manner indicated by the solid line and the phase characteristic in the wireless power transmission indicated by the broken line indicates that the response of the wireless power transmission indicated by the broken line is delayed with respect to the response of the wired manner indicated by the solid line by 9 degrees, for example, when sinewaves of 100 Hz are input. The fine-motion stage503was driven in the X-axis direction from a stage position P0to a stage position P1in a manner illustrated inFIG.20in the state in which the phase of the wireless power transmission indicated by the broken line is delayed with respect to the phase of the wired manner indicated by the solid line.FIG.21indicates the stage deviation at that time. Referring toFIG.21, a solid line indicates the stage deviation in the wired manner and a broken line indicates the stage deviation in the wireless power transmission. Since the response in the wireless power transmission indicated by the broken line is delayed with respect to the response in the wired manner indicated by the solid line, the control performance of the fine-motion stage503was degraded and the large stage deviation occurred.

FIG.22Ais a diagram illustrating an example of the configuration of a control apparatus610including a phase compensator602. The control apparatus610inFIG.22Aresults from addition of the phase compensator602to the control apparatus600inFIG.18. The phase compensator602is provided between the PID controller601and the linear motor driver506. The phase compensator602receives the value output from the PID controller601, performs the phase compensation, and supplies the driver instruction value to the linear motor driver506. The phase compensator602corresponds to the phase compensator400inFIG.12.

The advantages of providing the phase compensator602inFIG.22Awill now be described. As described above, the phase characteristic in the power transmission using the wireless power transmission system507is delayed with respect to the phase characteristic in the wired manner. A transmission function H(z) of the phase compensator602having a characteristic advancing the phase so as to offset the delay of the phase characteristic is expressed by Expression (7):

Coefficients a1, a2, b0, b1, and b2 in Expression (7) correspond to the weighting coefficients a1, a2, b0, b1, and b2 inFIG.16. Although Expression (7) is an equation when the phase compensator602is installed as the digital circuit, the phase compensator602may be installed as the analog circuit. The weighting coefficients a1, a2, b0, b1, and b2 of the phase compensator602are adjusted so as to compensate the difference in the phase characteristic between the power transmission using the wireless power transmission system507and the power transmission in the wired manner. For example, the weighting coefficients a1, a2, b0, b1, and b2 have the following values to compensate the delay in the phase characteristic inFIGS.19: a1−−1.001815, a2=0.198548, b0=1.908796, b1−−2.090536, and b2=0.401394. The phase compensator602having the characteristic inFIG.23is capable of being installed by using these weighting coefficients.

FIG.22Bis a diagram illustrating an example of the configuration of another control apparatus620including the phase compensator602. The control apparatus620inFIG.22Bresults from addition of the phase compensator602to the control apparatus600inFIG.18. The phase compensator602is provided between the linear motor driver506and the wireless power transmission system507. The phase compensator602receives the motor drive current output from the linear motor driver506, performs the phase compensation, and supplies the motor drive current to the wireless power transmission system507. The phase compensator602corresponds to the phase compensator300inFIG.10.

FIG.24is a graph indicating the closed loop phase characteristics of the position feedback control system in the X-axis direction of the fine-motion stage503when the power transmission is performed using the wireless power transmission system507with phase compensator602inFIG.22Band when the power transmission is performed using the wired manner. Referring toFIG.24, a solid line indicates the closed loop phase characteristic in the power transmission in the wired manner and a broke line indicates the closed loop phase characteristic in the power transmission using the wireless power transmission system507. Comparison between the phase characteristic in the wired manner indicated by the solid line and the phase characteristic in the wireless power transmission indicated by the broken line indicates that the response of the wireless power transmission indicated by the broken line is delayed with respect to the response of the wired manner indicated by the solid line by 0.1 degrees, that is, little delay occurs, for example, when sinewaves of 100 Hz are input. The fine-motion stage503was driven in the same manner as inFIG.20in the state in which the closed loop phase characteristic in the wired manner indicated by the solid line substantially coincides with the closed loop phase characteristic in the wireless power transmission indicated by the broken line.FIG.25indicates the stage deviation at that time. Referring toFIG.25, a solid line indicates the stage deviation in the wired manner and a broken line indicates the stage deviation in the wireless power transmission. Since the phase characteristic of the fine-motion stage503in the wireless power transmission indicated by the broken line was equivalent to the phase characteristic of the fine-motion stage503in the wired manner indicated by the solid line, the control performance of the fine-motion stage503in the wireless power transmission was equivalent to that in the wired manner. As a result, the stage deviation in the wireless power transmission was equivalent to the stage deviation in the wired manner.

As described above, the fine-motion linear motor504corresponds to the motor104of the first and second embodiments and applies the thrust to the fine-motion stage503, which is driven with an object being held. The fine-motion stage503is a stage apparatus.

At least one fine-motion linear motor504may be configured on the fine-motion stage503. In this case, the wireless power transmission system507is connected to each fine-motion linear motor504. The wireless power transmission system507transmits the power to at least one fine-motion linear motor504.

The above embodiments are only examples to embody the aspects of the invention and provide disclosure. The scope of the invention is not limitedly interrupted solely by the disclosed embodiments. In other words, the invention and accompanying disclosure may be embodied in various modes without departing from the technical idea or the main features recited, individually or in combination, in the claims.

Other Embodiments

While the present invention has been described with reference to embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. Each of the embodiments of the present invention described above can be implemented solely or as a combination of a plurality of the embodiments or features thereof where necessary or where the combination of elements or features from individual embodiments in a single embodiment is beneficial. 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 the benefit of Japanese Patent Application No. 2022-155990, filed Sep. 29, 2022, which is hereby incorporated by reference herein in its entirety.