JP2016021789A - Pressure control device and vacuum system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure control device for an APC valve in which an A/D converter accurately samples signals, and a vacuum system including the same.SOLUTION: A controller 37 for an APC valve 3 sets an amplitude of a carrier greater than that of a voltage command signal and then generates a switching signal for driving a three-phase inverter 35. A period including a time in which a noise level is low (first low noise time) is generated under an OFF state of high-side switching elements of all three phases and an ON state of low-side switching elements of all three phases in the three-phase inverter 35. An A/D converter 36 performs sampling for the first low noise level time. Similarly, a controller 47 also generates a second low noise time. The controller 37 and the controller 47 communicate and temporally overlap the first low noise time and the second low noise time. The A/D converter 36 performs sampling for the overlapped time preferably.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pressure control device and a vacuum system.

  The APC valve is provided between the vacuum processing apparatus and the vacuum pump in order to set the pressure in the vacuum chamber of the vacuum processing apparatus to a predetermined value.

  A pressure setting command signal and a pressure detection signal of the vacuum chamber of the vacuum processing apparatus are input from the vacuum processing apparatus to the APC valve. The APC valve receives these signals by the AD converter, samples them at a predetermined timing, and sends them to the controller provided in the APC valve to the digital value of the pressure setting value obtained from the pressure setting command signal and the pressure detection The digital value of the pressure detection value obtained from the signal is transmitted.

  The controller compares these two digital values and opens the opening of the valve plate of the APC valve provided in the APC valve so that the digital value of the pressure detection value becomes the digital value of the pressure setting value, that is, the valve Feedback control of the rotation angle of the motor to which the plate is connected. As a result, the APC valve controls the pressure in the vacuum chamber of the vacuum processing apparatus.

  The controller of the APC valve controls the motor through an inverter. The inverter has a switching element, and controls the voltage applied to the motor by turning on and off the switching element.

  When the switching element is turned on or turned off, switching noise may be superimposed on the pressure setting command signal and the pressure detection signal of the vacuum chamber. This switching noise is greatest when it is in an on state or an off state, and decays with time.

JP 62-287165 A

  Patent Document 1 discloses an invention in which a plurality of samples are sampled, an average value is calculated using a value excluding the maximum value and the minimum value, and the average value is output as a digital value. However, in the invention described in Patent Document 1, sampling may be performed at a time when the switching noise described above is not sufficiently attenuated. With the values obtained by such sampling, there is a problem that switching noise cannot be sufficiently removed even if averaged.

(1) A pressure control device according to a preferred embodiment of the present invention at least reads a first three-phase inverter that drives a three-phase motor that controls the position of a valve plate for an APC valve, a pressure setting command signal, and a pressure detection signal. An AD converter that converts the signal into a digital signal, and a first controller that generates a first switching signal to be transmitted to the first three-phase inverter in order to control the position of the valve plate according to the digital signal. When the first controller generates the first switching signal, all the three-phase high-side switching elements of the first three-phase inverter are on and all the three-phase low-side switching elements are off. Is a period including a first low noise time that is equal to or lower than a predetermined level, or all three-phase high-side switching elements of the first three-phase inverter are in an off state and all three-phase low-side switching elements are in an on state. A first period that is a period including the first low noise time is detected. The AD converter samples the pressure setting command signal and the pressure detection signal in the first low noise time.
(2) A vacuum system according to a preferred aspect of the present invention generates a second switching signal to be transmitted to a pressure control device according to a preferred aspect of the present invention and a second three-phase inverter that drives a motor that rotates a pump rotor. A vacuum pump having a controller. The second controller has a second low noise in which all the three-phase high-side switching elements of the second three-phase inverter are on and all the three-phase low-side switching elements are off and the second switching noise is below a predetermined level. A period including time, or a period including all of the high-side switching elements of all the three phases of the second three-phase inverter in the off state and all the low-side switching elements of the three phases in the on state and including the second low noise time. A certain second period is detected. The first controller and the second controller cause the first low noise time and the second low noise time to overlap in time. The AD converter samples the pressure setting command signal and the pressure detection signal within a period in which the first low noise time and the second low noise time overlap.

  According to the present invention, the influence of switching noise can be reduced without impairing the reliability of the digital value of the pressure set value and the digital value of the pressure detection value.

The figure which shows the vacuum system by 1st Embodiment of this invention. The figure which showed the waveform compared with each other by the controller in the control apparatus of an APC valve. The figure which showed an example (three-phase constant current waveform) and carrier wave of a voltage command signal. The figure which showed an example (three-phase alternating current waveform) of a voltage command signal. The figure which showed the production | generation of a switching signal, and the timing which AD converter of the control apparatus of an APC valve samples. The figure which showed the production | generation of a switching signal, and the timing which AD converter of the control apparatus of an APC valve samples. The figure which shows the vacuum system by 2nd Embodiment of this invention. The figure shown about how to make two low noise time overlap in 2nd Embodiment. The figure for demonstrating the modification 2 of the control apparatus of an APC valve. The figure for demonstrating the modification 3 of the control apparatus of an APC valve. The block diagram of a three-phase inverter. The figure which showed the relationship between the amplitude of a general carrier wave and a voltage command signal. The figure for demonstrating the production | generation of the switching signal in 2nd Embodiment.

-First embodiment-
FIG. 1 shows an exhaust system and a block diagram of the vacuum system 1 of the first embodiment. The vacuum system 1 includes a vacuum processing device 2, an APC valve 3, and a vacuum pump 4.

  The vacuum processing apparatus 2 includes a vacuum chamber 23, a diaphragm 22, and a controller 21. Various processes such as etching of the semiconductor substrate are performed in the vacuum chamber 23. The diaphragm 22 is provided in the vacuum chamber 23, detects the pressure in the vacuum chamber 23, and transmits a pressure detection signal S2 to the APC valve 3. The controller 21 transmits a pressure setting command signal S1 to the APC valve 3 so as to set the pressure (degree of vacuum) in the vacuum chamber 23 to a predetermined value.

  The vacuum pump 4 includes an evacuation system 42, a pump rotor 41, a motor 40, a three-phase inverter 45, a current detector 48, an AD converter 46, and a controller 47.

  The vacuum pump 4 evacuates the vacuum chamber 23 of the vacuum processing apparatus 2 through the exhaust path 50 by rotating a pump rotor 41 provided in the evacuation system 42 by a motor 40. The gas exhausted by the vacuum pump 4 is exhausted by a back pump connected to the vacuum exhaust downstream side of the vacuum pump 4.

  The APC valve 3 is provided between the vacuum processing apparatus 2 and the vacuum pump 4 in the exhaust path 50. The APC valve 3 includes a valve plate 32, a motor 30, and a control device 3A.

  The valve plate 32 is provided in an exhaust path 50 that connects the vacuum chamber 23 of the vacuum processing apparatus 2 and the vacuum exhaust system 42 of the vacuum pump 4. The control device 3A controls the opening angle of the valve plate 32 by controlling the rotation angle of the motor 30, thereby adjusting the gas flow rate in the exhaust passage 50 and controlling the pressure in the vacuum chamber 23 to a predetermined value. ing.

  The control device 3A includes a three-phase inverter 35, a current detector 38, an AD converter 36, and a controller 37.

  The controller 37 generates a voltage command signal based on a signal (described later) from the AD converter 36 and a signal of the position of the valve plate 32 output from the motor 30, and the voltage command signal Vref and a carrier wave Vc which is a triangular carrier wave. Are compared to generate a three-phase PWM signal (switching signal). Then, the controller 37 outputs a switching signal to the three-phase inverter 35. The controller 37 also transmits a switching signal to the AD converter 36. This is because the AD converter 36 obtains the sampling timing. In the present embodiment, the controller 37 and the controller 47 of the vacuum pump 4 need not communicate with each other. Details of the process of generating a three-phase PWM signal (switching signal) by comparing the voltage command signal Vref and the carrier wave Vc in the controller 37 will be described later.

  As shown in FIG. 11, the three-phase inverter 35 includes a high-side switching element U + in the U-phase, a low-side switching element U− in the U-phase, a high-side switching element V + in the V-phase, and a low-side switching element V in the V-phase. -, A high-side switching element W + in the W-phase, and a low-side switching element W- in the W-phase.

  In FIG. 1, a three-phase inverter 35 is not shown by turning on / off switching elements U +, U−, V +, V−, W +, and W− shown in FIG. 11 based on a switching signal from a controller 37. A three-phase alternating current is applied to the motor 30 as a load using the output of the power source.

  The current detector 38 is provided between the three-phase inverter 35 and the motor 30, detects the above-described three-phase alternating current, and outputs the current value signal to the AD converter 36.

  The AD converter 36 obtains the sampling timing based on the three-phase PWM switching signal output from the controller 37, and acquires and monitors the three-phase alternating current flowing in the motor 30 output from the current detector 38, while FIG. 6, the pressure setting command signal S <b> 1 output from the controller 21 of the vacuum processing apparatus 2 and the pressure detection signal S <b> 2 output from the diaphragm 22 are sampled and converted into digital values. Then, these digital values are output to the controller 37.

  The motor 30 rotates based on the three-phase alternating current applied from the three-phase inverter 35 and controls the position (opening degree) of the valve plate 32. Thus, the gas flow rate in the exhaust path 50 is controlled, and the pressure (degree of vacuum) in the vacuum chamber 23 is controlled. Further, the motor 30 outputs information on the position (opening) of the valve plate 32 to the controller 37.

  FIG. 2 is a diagram showing the voltage command signal Vref and the carrier wave Vc compared by the controller 37. Since the voltage command signal Vref is output with various waveforms according to the driving conditions, a specific waveform is not shown, and a region where the waveform of the voltage command signal Vref is shown is hatched.

  Specific examples of the voltage command signal Vref to be shown in FIG. 2 include (three-phase) constant current waveforms shown in FIG. 3 and (three-phase) AC waveforms shown in FIG. The constant current waveform shown in FIG. 3 is used when the valve plate 32 is maintained at a predetermined position. The AC waveform shown in FIG. 4 is used when the valve plate 32 of the APC valve 3 shown in FIG. 1 is moved. As shown in FIGS. 3 and 4, the voltage command signals for the U phase, the V phase, and the W phase are Vref_U, Vref_V, and Vref_W, respectively.

  In the present embodiment, for the carrier wave Vc, a common carrier wave Vc, that is, a carrier wave Vc having the same shape and the same phase, is used in three phases (U phase, V phase, W phase).

  As shown in FIG. 12, the amplitude of the general carrier wave Vc is set equal to the upper limit value | Vref | _Max of the amplitude of the voltage command signal Vref. However, the amplitude of the carrier wave Vc in this embodiment is set to be larger than the upper limit value | Vref | _Max of the amplitude of the voltage command signal Vref as shown in FIG.

  With reference to FIG. 5, a switching signal generation method in the case of the constant current waveform shown in FIG. 3, a method for obtaining an all-phase high-off-low-on period described later, and sampling timing of the AD converter 36 will be described. The same applies to the three-phase alternating current shown in FIG.

  FIG. 5A shows the voltage command signals Vref_U, Vref_V, Vref_W and the carrier wave Vc in the case of the constant current waveform shown in FIG. FIG. 5B shows the switching signals SUH, SVH, SWH of the high-side switching elements (see FIG. 11) of each phase and the switching signals SUL, SVL, SWL of the low-side switching elements, which are generated by comparison between them. ing. The signal generation processing as shown in FIGS. 5A and 5B is executed in the controller 37 of the APC valve 3. FIG. 5C shows the switching noise NS in the all-phase high-off-low-on period described later. FIG. 5D shows the sampling timing of the AD converter 36 shown in FIG. In each of the switching signals SUH, SUL, SVH, SVL, SWH, SWL, the upper side in the figure indicates the on state, and the lower side in the figure indicates the off state.

  Here, in order to simplify the description, “high off-low on period”, “high on-low off period”, “all phase high off—low on period”, and “all phase high on—low off period” are defined below.

<High off-low on period>
In a certain phase, a period in which the high-side switching element is off and the low-side switching element is on is called a high-off-low-on period.

<High on-low off period>
In a certain phase, a period in which the high side switching element is on and the low side switching element is off is referred to as a high on-low off period.

<All phase high-off to low-on period>
In all three phases, a period that is a high-off-low-on period is referred to as an all-phase high-off-low-on period.

<All-phase high-on-low-off period>
In all three phases, a period that is a high on-low off period is referred to as an all-phase high on-low off period.

  As shown in FIG. 5A, the voltage command signal Vref_U and the carrier wave Vc intersect at intersections CR1 and CR2. As a result, as shown in FIG. 5B, the timing at which the signal SUH shifts from the on state to the off state is determined at the intersection CR1. At the intersection CR2, the timing at which the signal SUH shifts from the off state to the on state is determined. That is, the period T4 during which the signal SUH is in the off state is determined by the intersection point CR1 and the intersection point CR2. The period T1 in which the signal SUL is in the on state is a period obtained by removing the dead time Td at both ends from the period T4. Here, the high-off-low-on period in the U phase is the period T1.

  In FIG. 5A, the voltage command signal Vref_V and the carrier wave Vc intersect at intersections CR3 and CR4. Since the voltage command signals of the V phase and the W phase match, the voltage command signal Vref_W and the carrier wave Vc also intersect at the intersections CR3 and CR4. Periods T5 and T7 in which the signals SVH and SWH are in the off state are generated by the intersection points CR3 and CR4. Similarly to the generation of the period T1, the periods T6 and T8 in which the signals SVL and SWL are in the on state are generated. Note that the period T5 and the period T7 are equal to each other, and the period T6 and the period T8 are equal to each other. Here, the high-off-low-on period in the V-phase is a period T6, and the high-off-low-on period in the W-phase is a period T8.

  In FIG. 5B, a period T1 that is a U-phase high-off-low-on period is included in a period T6 that is a V-phase high-off-low-on period and a period T8 that is a W-phase high-off-low-on period. Here, “inclusion” is a concept including “match”. In general three-phase PWM control, the high-off-low-on period of the first phase is included in the high-off-low-on period of the second phase, and the high-off-low-on period of the second phase is included in the high-off-low-on period of the third phase. Is done. FIG. 5B shows a case where the high-off-low-on period of the V phase that is the second phase and the high-off-low-on period of the W phase that is the third phase coincide.

  As described above, the high-off-low-on period of each of the three phases is obtained, and when the inclusive relation is known, the all-phase high-off-low-on period is obtained. In the example shown in FIG. 5, the period T1 which is a period included in another phase is an all-phase high-off-low-on period.

  The controller 37 shown in FIG. 1 obtains a low noise time T3 in which switching noise is substantially not superimposed after obtaining a period T1 that is an all-phase high off-low on period. FIG. 5C shows the switching noise NS in the period T1 that is the all-phase high-off-low-on period. Switching noise is noise that is generated by switching between an on state and an off state and attenuates with time. Therefore, switching noise is generated as the switching state of each switching element shown in FIG. 5B is switched. However, in the period T1 that is the all-phase high-off-low-on period, the most serious problem is the switching noise NS that has occurred most recently, that is, at the start time ts1 of the period T1, and therefore, only that need be noted. As shown in FIG. 5C, the switching noise NS attenuates with time. The controller 37 predetermines a predetermined threshold value LTH that is not problematic for the AD converter 36 to sample, and the time point ts2 when the noise level of the switching noise NS falls below the threshold value LTH is a boundary from the start time point ts1 to the time point ts2. Up to the high noise time T2, and from the time ts2 to the end time ts3 of the period T1, the low noise time T3.

  As shown in FIG. 1, the controller 37 transmits the switching signals SUH, SUL, SVH, SVL, SWH, SWL not only to the three-phase inverter 35 but also to the AD converter 36. At that time, the controller 37 also transmits the timing signal of the above-described low noise time T3 to the AD converter 36.

  The AD converter 36 acquires and monitors the current value of the current detector 38 shown in FIG. 1 based on the information from the controller 37, and receives the timing signal entering the period T3 as shown in FIG. 5D. The pressure setting command signal S1 and the pressure detection signal S2 are sampled. Note that the current value signal from the current detector 38 may also be sampled.

  As described above, since the switching noise NS attenuates with time, the noise level is reduced most in the vicinity of the end time ts3 in the low noise time T3. Therefore, the AD converter 36 preferably samples the pressure setting command signal S1 and the pressure detection signal S2 in the vicinity of the end time ts3 within the low noise time T3.

  In FIG. 5, the case of the constant current waveform as shown in FIG. 3 has been described. However, the present invention is not limited to this, and as shown in FIG. 6, the invention of the present embodiment can also be applied to the three-phase AC waveform shown in FIG. 4. In the case of a three-phase AC waveform, as a matter of course, the value of the voltage command signal for each of the three phases changes with a phase difference of 120 degrees. As a result, the three-phase switching timings are different from each other, so that the periods during which the high-side switch is off and the low-side switch is on are different from each other for the three phases. As a result, as shown in FIG. 6, for example, a high-off-low-on period T1 in the U-phase is included in a high-off-low-on period T6 in the V-phase, and further, a high-off-low-on period T6 in the V-phase is included in the W phase. A state is generated that is included in the high-off-low-on period T8. The difference between FIG. 6 and FIG. 5 is that the high-off-low-on period T6 in the V-phase does not coincide with the high-off-low-on period T8 in the W phase and that the U phase, V phase, W The relationship of the phases is changed.

According to the first embodiment, the following operational effects can be obtained.
(1) The control device 3A includes a three-phase inverter 35 that drives a three-phase motor 30 that controls the position (rotation angle, opening) of the valve plate 32 of the APC valve 3, a pressure setting command signal S1, and a pressure detection signal. AD converter 36 which reads S2 and converts it into a digital signal, and switching signals SUH, SUL, which are transmitted to three-phase inverter 35 in order to control the position of valve plate 32 in accordance with the digital signal output from AD converter 36 And a controller 37 for generating SVH, SVL, SWH, and SWL.
When the controller 37 generates the switching signals SUH, SUL, SVH, SVL, SWH, SWL, all the three-phase high-side switching elements U +, V +, W + of the three-phase inverter 35 are in the OFF state and all the three phases A period in which the low-side switching elements U−, V−, and W− are in an on state and includes a low noise time T3, that is, a period T1 that is an all-phase high off-low on period is detected.
The AD converter 36 samples the pressure setting command signal S1 and the pressure detection signal S2 during the low noise time T3.
Thereby, the pressure setting command signal S1 and the pressure detection signal S2 with less noise can be obtained. As a result, pressure control can be performed with high accuracy.

  Conventionally, the sampling timing of the AD converter is not synchronized with the switching signal, and the AD converter samples even when the switching noise is not attenuated. As a result, since the S / N ratio of the signal sampled by the AD converter was small, a large number of samplings were performed and the signals were averaged to obtain a signal. Since it is necessary to perform many samplings for one type of signal (for example, pressure setting command signal), in order to sample a plurality of types of signals, it is possible to simultaneously sample a plurality of types of signals. It was necessary to use a simple synchronous AD converter.

  However, since the sampled signal obtained in this embodiment has a high S / N ratio, it is not necessary to perform a lot of processing such as sampling and averaging thereof. Further, since it is sufficient to use an inexpensive asynchronous AD converter, the cost of the system can be reduced.

(2) The AD converter 36 may sample the current value signal from the current detector 38 in addition to sampling the pressure setting command signal S1 and the pressure detection signal S2. Thereby, the accuracy of control of the motor 30 is improved.

(3) The AD converter 36 preferably samples the pressure setting command signal S1 and the pressure detection signal S2 in the vicinity of the end time ts3 of the low noise time T3.
Thus, since sampling is performed when the switching noise is sufficiently attenuated, the pressure setting command signal S1 and the pressure detection signal S2 with less noise can be obtained. As a result, pressure control can be performed with higher accuracy.

(4) The controller 37 generates the switching signals SUH, SUL, SVH, SVL, SWH, SWL by comparing the carrier wave Vc and the voltage command signal Vref, and the carrier wave Vc is generated from the voltage command signals Vref of all three phases. Is also detected as the all-phase high-off-low-on period.
Thereby, when the switching signal is generated by comparing the carrier wave and the voltage command signal, the all-phase high-off-low-on period can be detected.

(5) The controller 37 makes the amplitude of the carrier wave Vc larger than the upper limit value | Vref | _Max of the amplitude of the voltage command signal Vref.
Thus, in the method of generating the switching signals SUH, SUL, SVH, SVL, SWH, SWL by comparing the carrier wave Vc and the voltage command signal Vref, all-phase high-off for any voltage command signal Vref− A low-on period or an all-phase high-on-low-off period can be generated.

-Second embodiment-
FIG. 7 shows an exhaust system and a block diagram of the vacuum system 1 of the second embodiment. In the vacuum system 1 of the second embodiment, as indicated by reference numeral 100, the controller 37 and the controller 47 of the vacuum pump 4 communicate with each other. This is the main difference from the first embodiment. The following description will be focused on the difference, and the description of the same configuration as that of the first embodiment will be omitted.

  The motor 40 of the vacuum pump 4 drives the pump rotor 41 to rotate. Therefore, the switching signal output from the controller 47 is a signal that causes a three-phase AC waveform to flow through the motor 40. The structure of the three-phase inverter 45 is the same as that of the three-phase inverter 35 as shown in FIG. The three-phase inverter 45 applies a three-phase alternating current to the motor 40 based on the switching signal. The current detector 48 detects the three-phase alternating current and outputs it to the AD converter 46. In order to know the sampling timing, the AD converter 46 obtains the switching signal from the controller 47 and information on the timing of the all-phase high-off-low-on period and all-phase high-on-low-off period. Based on the information, the current value signal from the current detector is sampled during the low noise time within the all-phase high-off-low-on period and the all-phase high-on-low-off period, as in the operation of the AD converter 36. It is more preferable to sample near the end point of the low noise time.

  In FIG. 7, the controller 37 of the control device 3 </ b> A of the APC valve 3 according to the present embodiment communicates with the controller 47 of the vacuum pump 4, as shown by the fact that the controller 37 and the controller 47 are connected by double-ended arrows. This is because, as shown below, the low-noise time (hereinafter referred to as the first low-noise time) of the all-phase high-off-low-on period and the all-phase high-on-low-off period of the three-phase inverter 35 of the control device 3A, the vacuum pump This is because the low-noise time (hereinafter referred to as second low-noise time) of the four-phase three-phase inverter 45 of the all-phase high-off-low-on period and the all-phase high-on-low-off period overlap each other.

  This will be specifically described with reference to FIGS. For the sake of explanation, in the present embodiment, the carrier wave Vc generated by the controller 37 is referred to as a carrier wave Vc1. The carrier wave Vc generated by the controller 47 is referred to as a carrier wave Vc2. FIG. 13A shows the carrier wave Vc1 and the voltage command signal Vref of each phase in the controller 37. FIG. 13B shows a switching signal obtained by comparing the carrier wave Vc1 shown in FIG. 13A and the voltage command signal Vref of each phase. However, in order to avoid complication of the figure, FIG. 13 (b) shows only the switching signal of the phase (U phase in the figure) most related to the all-phase high-off-low-on period. FIG. 13 (d) shows the carrier wave Vc2 and the voltage command signal Vref for each phase in the controller 47. FIG. 13C shows a switching signal obtained by comparing the carrier wave Vc2 shown in FIG. 13D and the voltage command signal Vref of each phase. However, in order to avoid complication of the figure, FIG. 13 (c) shows only the switching signal of the phase (U phase in the figure) most related to the all-phase high-off-low-on period.

  In the present embodiment, as indicated by reference numeral 100 in FIG. 7, the controller 37 of the control device 3 </ b> A of the APC valve 3 transmits information on the carrier wave Vc <b> 1 used by the controller 37 itself to the controller 47 of the vacuum pump 4. The controller 37 compares the carrier wave Vc1 with the voltage command signal Vref of each phase as shown in FIG. 13A, and generates an all-phase high off-low on period TN3 as shown in FIG. 13B. On the other hand, the controller 47 generates a carrier wave Vc2 having the same period and the same phase as the carrier wave Vc1, based on the carrier wave Vc1 received from the controller 37. Here, the in-phase means that the vertex 71 of the carrier wave Vc1 shown in FIG. 13 (a) and the vertex 72 of the carrier wave Vc2 having the same period as the carrier wave Vc1 shown in FIG. To do. Then, the controller 47 generates an all-phase high-off-low-on period TN6 as shown in FIG. 13C, as compared with the voltage command signal Vref for each phase as shown in FIG. 13D. The amplitude of the carrier wave Vc2 is set larger than the amplitude of the voltage command signal Vref for each phase used in the controller 47.

  Thus, since the controller 37 and the controller 47 temporally match the vertex 71 of the carrier wave Vc1 and the vertex 72 of the Vc2, as shown in FIGS. 13 (b) and 13 (c), the controller 37 The generated all-phase high-off-low-on period TN3 and the all-phase high-off-low-on period TN6 generated by the controller 47 can overlap in time. Further, since the amplitudes of the carrier waves Vc1 and Vc2 and the lengths of the periods can be changed, the lengths of the all-phase high-off / low-on periods TN3 and TN6 of the controller 37 and the controller 47 can be changed. If the amplitude and period are appropriately adjusted, the first low noise time TN2 and the second low noise time TN5 can be overlapped as shown in FIGS. 13 (b) and 13 (c). In this embodiment, the information on the carrier wave Vc1 is transmitted from the controller 37 to the controller 47, but the information on the carrier wave Vc2 is transmitted from the controller 47 to the controller 37, and the controller 37 determines the carrier wave Vc1 based on the information on the carrier wave Vc2. You may make it produce | generate.

  Here, the overlap of the first low noise time and the second low noise time will be further described with reference to FIG. For simplicity, consider only the high-off-low-on period for all phases. In this embodiment, the switching signal is generated by comparing the carrier wave Vc and the voltage command signal Vref. However, the method of generating the switching signal is not limited to this.

  In FIG. 8A, a switching signal S35 (upper side in the figure) indicating the all-phase high off-low on period in the three-phase inverter 35, and a switching signal S45 (lower side in the figure) indicating the all-phase high off-low on period in the three-phase inverter 45. The overlap between the first low noise time and the second low noise time will be described. The “switching signal indicating the all-phase high-off-low-on period” corresponds to, for example, the signal SUL in the case of FIG. Since the pulse width varies depending on the driving conditions, the figure is an example.

  The all-phase high-off-low-on period in the three-phase inverter 35 is a period TN3 indicated by the signal S35. The period TN3 includes a first high noise time TN1 and a first low noise time TN2 that follows the first high noise time TN1. The time point ts2, which is a temporal separation between the first high noise time TN1 and the first low noise time TN2, is determined by whether or not the switching noise is equal to or less than the threshold value LTH as shown in FIG. 5 (c) or FIG. 6 (c). Is done.

  Similarly, the all-phase high-off-low-on period in the three-phase inverter 45 is a period TN6 indicated by the signal S45. The period TN6 includes a second high noise time TN4 and a second low noise time TN5 that follows the second high noise time TN4. A time point ts5, which is a time interval between the second high noise time TN4 and the second low noise time TN5, is determined by whether or not the switching noise is equal to or less than a threshold value LTH as shown in FIG. 5C or FIG. 6C. Is done.

  If only the signal S35 is considered, the AD converter 36 of the control device 3A of the APC valve 3 may perform sampling in the first low noise time TN2. However, in this embodiment, it is necessary to consider not only the signal S35 but also the signal S45. Therefore, in consideration of the signal S35 and the signal S45, the AD converter 36 needs to sample in the period TOL in which the first low noise time TN2 and the second low noise time TN5 overlap.

According to the second embodiment, the following operational effects can be obtained.
(1) The vacuum system 1 includes a control device 3A for the APC valve 3 and a vacuum pump 4 having a controller 47 that generates a switching signal to be transmitted to a three-phase inverter 45 that drives a motor 40 that rotates the pump rotor 41. Prepare.
The controller 47 is in a state where all the three-phase high-side switching elements U +, V +, W + of the three-phase inverter 45 are in the OFF state and all the three-phase low-side switching elements U−, V−, W− are in the ON state. A period TN6 that is a period including the noise time TN5 is detected.
The controller 37 of the control device 3A of the APC valve 3 and the controller 47 of the vacuum pump 4 cause the first low noise time TN2 and the second low noise time TN5 to overlap in time.
The AD converter 36 of the control device 3A of the APC valve 3 samples the pressure setting command signal S1 and the pressure detection signal S2 within a period TOL in which the first low noise time TN2 and the second low noise time TN5 overlap.
As a result, not only the switching noise in the APC valve 3 but also the switching noise of the vacuum pump 4 is hardly affected, and the S / N ratio of the signal sampled by the AD converter 36 of the control device 3A of the APC valve 3 is improved. To do. As a result, the accuracy of pressure control of the APC valve 3 is improved.

(2) It is preferable that the AD converter 36 of the control device 3A of the APC valve 3 performs sampling in the vicinity of the end points ts3 and ts6 within the period TOL.
As a result, further improvement in the S / N ratio can be expected.

(3) The AD converter 46 of the vacuum pump 4 is also within the period TOL in which the first low noise time TN2 and the second low noise time TN5 overlap, as in the AD converter 36 of the control device 3A of the APC valve 3. In this case, it is preferable to sample the current value signal.
This improves the S / N ratio of the current value signal. As a result, the accuracy of drive control of the motor 40 is improved.

-Modification of the second embodiment-
FIG. 8B shows a more preferable example of the second embodiment shown in FIG. The feature in FIG. 8B is that the end time ts3 of the first low noise time TN2 and the end time ts6 of the second low noise time TN5 coincide. Specifically, the phases of the carrier waves Vc1 and Vc2 are shifted, for example, the carrier wave Vc1 shown in FIG. 13A is advanced in time with respect to the carrier wave Vc2 shown in FIG. Thus, the end time ts3 of the first low noise time TN2 and the end time ts6 of the second low noise time TN5 can be matched. In addition, the end time ts3 of the first low noise time TN2 and the end time ts6 of the second low noise time TN5 can be matched by reducing the amplitude of the carrier wave Vc1 shown in FIG. it can.

  As described in the embodiment of the control device 3A, the switching noise attenuates with time. That is, the noise level is the lowest in the vicinity of the end time ts3 within the first low noise time TN2. Further, the noise level is the lowest in the vicinity of the end time ts6 within the second low noise time TN5. Therefore, when the first low noise time TN2 and the second low noise time TN5 are overlapped in time, it is preferable to overlap the end point ts3 and the end point ts6 so as to coincide with each other in order to reduce the noise level. . The AD converter 36 of the control device 3A of the APC valve 3 samples the pressure setting command signal S1 and the pressure detection signal S2 in the period TOL obtained in this way, so that the AD converter of the control device 3A of the APC valve 3 is sampled. The S / N ratio of the signal sampled by 36 is further improved. As a result, the accuracy of pressure control of the APC valve 3 is further improved.

  In this modification, the AD converter 36 of the control device 3A of the APC valve 3 samples the pressure setting command signal S1 and the pressure detection signal S2 near the time points ts3 and ts6 within the period TOL, so that the APC valve 3 The S / N ratio of the signal sampled by the AD converter 36 of the control device 3A is further improved. As a result, the accuracy of pressure control of the APC valve 3 is further improved.

  In this modification, rather than adopting a method of generating a switching signal by comparing the carrier wave Vc and the voltage command signal Vref as shown in the second embodiment, the PWM control program described in Modification 4 described later is used. It is easier to adopt a method for generating a switching signal. This is because the generation method using the PWM control program can relatively freely set the generation timing of the switching signal within the PWM cycle.

  In the first and second embodiments, the following modifications can be made.

—Modification 1 of the control device 3A for the APC valve 3—
In the above description, the AD converter 36 samples the pressure setting command signal S1 and the pressure detection signal S2 during the low noise time T3 of the all-phase high-off-low-on period. The signal S1 and the pressure detection signal S2 may be sampled.

—Modification 2 of the control device 3A for the APC valve 3—
FIG. 9 shows a voltage command signal Vref and a carrier wave Vc in the second modification. In the case of constant current control, due to the structure of the three-phase motor, the two-phase value of the three-phase voltage command signal is the opposite of the remaining one-phase value and the absolute value is half of the remaining one-phase value. It becomes a relationship. For example, in the case shown in FIG. 9, the V-phase voltage command signal Vref_V and the W-phase voltage command signal Vref_W are opposite in sign to the U-phase voltage command signal Vref_U and have an absolute value half that of the voltage command signal Vref_U. ing. Therefore, even if the U-phase voltage command signal Vref_U is located at one of the upper limit values + | Vref | _Max of the amplitude, the voltage command signal Vref_V and the voltage command signal Vref_W are the other of the upper limit values of amplitude − | Vref | _Max. Not located.

  In such a case, the carrier wave Vc does not become larger than the amplitude of the voltage command signal Vref, that is, the amplitude of the carrier wave Vc is changed to the amplitude of the voltage command signal Vref as in the general setting shown in FIG. Is set equal to, an all-phase high on-low off period is generated. Therefore, the AD converter 36 has only to sample the pressure setting command signal S1 and the pressure detection signal S2 in the low noise time of this all-phase high-on-low-off period.

—Modification 3 of the control device 3A for the APC valve 3—
FIG. 10 shows the voltage command signal Vref and the carrier wave Vc in the third modification. In this modification, the upper limit value | Vref | _Max of the amplitude of the carrier wave Vc and the amplitude of the voltage command signal Vref is set to be equal.

  In the case of this modification in which driving is performed that does not require much output, the voltage command signal Vref may not reach the upper limit of the amplitude, as indicated by the hatched area in FIG.

  In the case of this modification, even when the amplitude of the carrier wave Vc and the upper limit value | Vref | _Max of the amplitude of the voltage command signal Vref are set equal, the carrier wave Vc has a value higher than the voltage command signal Vref in all three phases. A large period or a period where the value of the carrier wave Vc is smaller than the voltage command signal Vref occurs in all three phases. Therefore, as shown in FIG. 5 and FIG. 6, since the all-phase high-off-low-on period and the all-phase high-on-low-off period are generated, the AD converter 36 is connected to the pressure setting command signal S1 in the low noise time of these periods. The pressure detection signal S2 may be sampled.

—Modification 4 of the control device 3A for the APC valve 3—
In the above embodiment, the switching signals SUH, SUL, SVH, SVL, SWH, SWL are generated by comparing the carrier wave Vc and the voltage command signal Vref. However, the switching signals SUH, SUL, SVH, SVL, SWH, SWL are It can also be generated by a PWM control program. In this modified example, if programmed so that the all-phase high-off-low-on period and the all-phase high-on-low-off period are generated, the AD converter 36 can sample the pressure setting command signal S1 and the pressure detection signal S2 with less noise. .

  In addition, the following modifications can be made.

  The present invention is not limited to the all-phase high-off-low-on period in both the controller 37 of the control device 3A of the APC valve 3 and the controller 47 of the vacuum pump 4. As shown in the first modification, it is also possible to apply the present invention during the all-phase high-on-low-off period. Further, in the vacuum system 1, the present invention can be applied in such a manner that the controller 37 of the APC valve 3 is in the all-phase high off-low on period and the controller 47 of the vacuum pump 4 is in the all phase high on-low off period.

  In the above description, the carrier wave Vc, which is the PWM carrier wave used by the controller 37 and the controller 47, is a triangular carrier wave. However, a sawtooth carrier wave may be used.

  While various embodiments and modifications have been described above, the present invention is not limited to these contents. Combinations of the above-described embodiments and modifications, and other modes conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention.

1: Vacuum system 2: Vacuum processing device 3: APC valve 3A: Control device 4: Vacuum pump 21: Controller 22: Diaphragm 23: Vacuum chamber 30: Motor 32: Valve plate 35: Three-phase inverter 36: AD converter 37: Controller 38: Current detector 40: Motor 41: Pump rotor 42: Vacuum exhaust system 45: Three-phase inverter 46: AD converter 47: Controller 48: Current detector 50: Exhaust path NS: Switching noise S1: Pressure setting command signal S2: Pressure detection signal T1 to T8: Period (time)
Td: Dead time Vc: Carrier wave LTH: Threshold value SUH, SUL, SVH, SVL, SWH, SWL: Switching signal S35, S45: Switching signal U +, V +, W +: High side switching elements U-, V-, W-: Low side Switching element TN1: First high noise time TN2: First low noise time TN4: Second high noise time TN5: Second low noise time TOL: Period ts3: End time ts6: End time Vref: Voltage command signal

Claims (8)

A first three-phase inverter that drives a three-phase motor that controls the position of the valve plate for the APC valve;
An AD converter that reads at least a pressure setting command signal and a pressure detection signal and converts them into a digital signal;
A first controller that generates a first switching signal to be sent to the first three-phase inverter to control the position of the valve plate in response to the digital signal;
When the first controller generates the first switching signal, all the three-phase high-side switching elements of the first three-phase inverter are on and all the three-phase low-side switching elements are off. A period including a first low noise time in which one switching noise is equal to or lower than a predetermined level, or the high-side switching elements of all three phases of the first three-phase inverter are in an off state and all the low-sides of all three phases Detecting a first period in which the switching element is in an ON state and includes the first low noise time;
The AD converter samples the pressure setting command signal and the pressure detection signal in the first low noise time. The pressure control device according to claim 1,
The AD converter is a pressure control device that samples the pressure setting command signal and the pressure detection signal in the vicinity of an end point of the first low noise time. The pressure control device according to claim 1 or 2,
The first controller includes:
The first switching signal is generated by comparing the first carrier wave and the first voltage command signal,
A pressure control device that detects a period in which the first carrier wave is larger than the first voltage command signal for all three phases or a period in which the first carrier wave is smaller than the first voltage command signal for all three phases as the first period. . The pressure control device according to claim 3.
The first controller is a pressure control device that makes an amplitude of the first carrier wave larger than an upper limit value of an amplitude of the first voltage command signal. The pressure control device according to any one of claims 1 to 4,
A vacuum pump having a second controller that generates a second switching signal to be transmitted to a second three-phase inverter that drives a motor that rotates a pump rotor;
In the second controller, all the three-phase high-side switching elements of the second three-phase inverter are in an on state and all the three-phase low-side switching elements are in an off state, and the second switching noise is less than a predetermined level. A period including a low noise time, or the high-side switching elements of all three phases of the second three-phase inverter are in the off state and all the low-side switching elements of the three phases are in the on state, Detecting a second period which is a period including a noise time;
The first controller and the second controller overlap the first low noise time and the second low noise time in time,
The AD converter is a vacuum system that samples the pressure setting command signal and the pressure detection signal within a period in which the first low noise time and the second low noise time overlap. The vacuum system according to claim 5,
The first controller and the second controller may match the first low noise time and the second low noise time by causing the end time of the first low noise time and the end time of the second low noise time to coincide with each other in time. Vacuum system that overlaps noise time in time. The vacuum system according to claim 5 or 6,
The second controller is
The second switching signal is generated by comparing the second carrier wave and the second voltage command signal,
A vacuum system for detecting, as the second period, a period in which the second carrier wave is larger than the second voltage command signal for all three phases or a period in which the second carrier wave is smaller than the second voltage command signal for all three phases. The vacuum system according to claim 7,
The second controller is a vacuum system in which an amplitude of the second carrier wave is made larger than an upper limit value of an amplitude of the second voltage command signal.

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