JP7809608B2 - Inverter control device, inverter control method, and inverter control program - Google Patents

Description

The present invention relates to an inverter control device, etc.

Patent Document 1 discloses a technique for adjusting the phase of harmonics as a control target in order to suppress divergence in an inverter feedback control system.

Japanese Patent Application Laid-Open No. 2008-245349

Patent Document 1 targets inverters in which switching elements perform switching operations in response to pulse width modulation (PWM) signals, and adjusts the phase of harmonics through software control. As such, the technology in Patent Document 1 is limited in its applicability to software-based PWM control.

The present invention was made in light of these circumstances, and aims to provide a highly versatile inverter control device, etc.

In order to solve the above problems, one embodiment of the present invention provides an inverter control device that controls an inverter that converts direct current to alternating current in response to a control signal applied to a control electrode of a switching element. The inverter control device includes an AC measurement unit that measures the AC output from the inverter, a high-pass filter that has a first cutoff frequency higher than the frequency of the AC and extracts higher-frequency components from the measured AC, a high-frequency removal unit that subtracts the extracted high-frequency components from the measured AC, and a control signal generation unit that generates a control signal that causes the switching element to perform switching operations in a linear region based on the AC from which the high-frequency components have been subtracted.

In this embodiment, the control signal generator can generate highly accurate control signals based on AC feedback from which high-frequency components that could become noise have been removed. This embodiment targets "linear control," which operates the inverter's switching elements in a linear region, but the high-pass filter, high-frequency removal unit, control signal generator, and other functions can be implemented in either software or hardware, making it highly versatile.

Another aspect of the present invention is an inverter control device. This device controls an inverter that converts direct current to alternating current in response to a control signal applied to a control electrode of a switching element, and includes an AC measurement unit that measures the AC output from the inverter, a hardware-implemented high-pass filter that has a first cutoff frequency higher than the frequency of the AC and extracts higher-frequency components from the measured AC, a hardware-implemented high-frequency removal unit that subtracts the extracted high-frequency components from the measured AC, and a control signal generation unit that generates a control signal based on the AC from which the high-frequency components have been subtracted.

In this embodiment, the control signal generation unit can also generate highly accurate control signals based on AC feedback from which high-frequency components that could become noise have been removed. While this embodiment targets a hardware-implemented high-pass filter and high-frequency removal unit, the control signal generation unit is highly versatile and can support a variety of control methods, including linear control and PWM control.

Another aspect of the present invention is an inverter control method. This method controls an inverter that converts direct current into alternating current in response to a control signal applied to a control electrode of a switching element, and includes an AC measurement step of measuring the AC output from the inverter, a high-frequency extraction step of extracting high-frequency components higher than a first cutoff frequency, which is higher than the frequency of the AC, from the measured AC, a high-frequency removal step of subtracting the extracted high-frequency components from the measured AC, and a control signal generation step of generating a control signal that causes the switching element to perform switching operations in a linear region, based on the AC from which the high-frequency components have been subtracted.

The present invention also encompasses any combination of the above components, as well as any conversion of these expressions into methods, devices, systems, recording media, computer programs, etc.

The present invention makes it possible to provide a highly versatile inverter control device, etc.

1 shows a schematic configuration of an inverter control device. The AC strength at each frequency is shown schematically.

The following describes in detail the form for carrying out the present invention (hereinafter also referred to as the embodiment) with reference to the drawings. In the description and/or drawings, the same or equivalent components, members, processes, etc. are designated by the same reference numerals, and redundant explanations are omitted. The scale and shape of each part shown in the drawings are set for convenience in order to simplify the explanation, and should not be interpreted as limiting unless otherwise specified. The embodiment is an example and does not limit the scope of the present invention in any way. All features and combinations thereof described in the embodiment are not necessarily essential to the present invention.

Figure 1 shows a schematic diagram of an inverter control device 30 according to an embodiment of the present invention. The inverter control device 30 controls an inverter 10, which is a DC-AC converter that converts DC to AC. The inverter 10 converts a DC voltage between a positive or high DC potential supplied from a positive potential line DCP and a negative or low DC potential supplied from a negative potential line DCN into a three-phase (U-phase, V-phase, and W-phase) AC voltage using six switching elements.

The inverter 10 includes a group of positive potential side switching elements 10P connected between the positive potential line DCP and the AC outputs of the respective UVW phases, and a group of negative potential side switching elements 10N connected between the negative potential line DCN and the AC outputs of the respective UVW phases. The group of positive potential side switching elements 10P includes three positive potential side switching elements corresponding to each of the UVW phases. The group of negative potential side switching elements 10N includes three negative potential side switching elements corresponding to each of the UVW phases.

Each switching element constituting the positive potential side switching element group 10P and/or the negative potential side switching element group 10N is preferably an IGBT (Insulated Gate Bipolar Transistor), but may also be another transistor or switching element such as a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), other FETs (Field-Effect Transistors), or bipolar transistors.

The positive-side switching element and the negative-side switching element of each phase of the U, V, and W phases constitute a pair of switching elements for each phase of the U, V, and W phases, whose switching is controlled complementarily. Specifically, the pair of positive-side and negative-side switching elements on the left side of Figure 1 constitutes a U-phase inverter that outputs a U-phase AC voltage from their connection point, the U-phase output terminal (indicated as "U"). The pair of positive-side and negative-side switching elements in the center of Figure 1 constitutes a V-phase inverter that outputs a V-phase AC voltage from their connection point, the V-phase output terminal (indicated as "V"). The pair of positive-side and negative-side switching elements on the right side of Figure 1 constitutes a W-phase inverter that outputs a W-phase AC voltage from their connection point, the W-phase output terminal (indicated as "W"). The U-phase inverter, V-phase inverter, and W-phase inverter are arranged in parallel between the positive potential line DCP and the negative potential line DCN. The inverters for the U, V, and W phases have the same configuration, so the following explanation will focus on the U-phase inverter (referenced 10).

The U-phase inverter 10 is provided between a positive potential line DCP that supplies a positive DC potential and a negative potential line DCN that supplies a negative DC potential, and has a U-phase output terminal "U" that outputs a U-phase AC voltage that fluctuates between the positive and negative potentials. A positive potential side switching element 10P is connected between the positive potential line DCP and the U-phase output terminal "U", and a negative potential side switching element 10N is connected between the negative potential line DCN and the U-phase output terminal "U". The conduction states of the positive potential side switching element 10P and the negative potential side switching element 10N are switched in response to control signals applied to their respective control electrodes from a driver 37, which will be described later.

The driver 37 converts the DC voltage between the positive potential line DCP and the negative potential line DCN into an AC voltage for the U phase by performing complementary switching of the conduction state of a switching element pair consisting of the positive potential side switching element 10P and the negative potential side switching element 10N. Here, "complementary switching" means controlling the switching element pairs of each phase so that they are not simultaneously turned on. In other words, when one switching element of each phase is turned on, the other switching element of that phase is controlled to be turned off. However, it is permissible for the switching element pairs of each phase to be simultaneously turned off. Specifically, for the U phase, when the positive potential side switching element 10P is turned on, the negative potential side switching element 10N is controlled to be turned off, and when the negative potential side switching element 10N is turned on, the positive potential side switching element 10P is controlled to be turned off. Therefore, when the positive potential side switching element 10P is in the ON state, the positive potential of the positive potential line DCP appears at the U-phase output terminal "U", and when the negative potential side switching element 10N is in the ON state, the negative potential of the negative potential line DCN appears at the U-phase output terminal "U". By periodically repeating this switching control, positive and negative potentials appear alternately at the U-phase output terminal "U", generating an AC voltage (U phase).

The inverter 10 converts DC voltage into three-phase AC voltage and supplies it to the motor 20 via, for example, an LC filter 11. The motor 20 is, for example, a three-phase brushless motor having three coils (not shown): U-phase, V-phase, and W-phase. The U-phase coil receives a U-phase voltage from the U-phase inverter, resulting in a U-phase current. The V-phase coil receives a V-phase voltage from the V-phase inverter, resulting in a V-phase current. The W-phase coil receives a W-phase voltage from the W-phase inverter, resulting in a W-phase current. The inverters 10 for each of the U, V, and W-phases apply AC voltages of different phases to the coils of each phase based on the rotational position of the rotor (not shown) detected by the Hall elements (not shown) of the motor 20. The AC voltages applied to the coils of each phase generate a rotating magnetic field, which rotates the rotor, which includes a magnet or the like, thereby generating the desired rotational power. The motor 20 may be any other type of motor driven by AC voltage. The number of phases of the motor 20 is not limited to three and may be any natural number.

The inverter control device 30 includes a current sensor 31, a low-pass filter (LPF) 32, a high-pass filter (HPF) 33, an inverter 34, an adder 35, a control signal generator 36, and a driver 37. Some or all of these components, particularly the low-pass filter 32, the high-pass filter 33, the inverter 34, the adder 35, the control signal generator 36, and the driver 37, may be implemented solely by hardware without using software (hereinafter simply referred to as "hardware implementation"), or may be implemented through a combination of software and general-purpose hardware (hereinafter simply referred to as "software implementation").

In a typical use case, hardware-implemented components process analog signals, so hardware implementation can also be referred to as analog implementation. Similarly, in a typical use case, software-implemented components process digital signals, so software implementation can also be referred to as digital implementation. Software-implemented components are realized through the cooperation of hardware resources such as the computer's central processing unit, memory, input devices, output devices, and peripheral devices connected to the computer, and software executed using these resources. Regardless of the type of computer or its location, each of the above components can be realized by the hardware resources of a single computer, or by combining hardware resources distributed across multiple computers.

The current sensor 31 is an AC measuring unit that measures the AC output from the inverter 10. The current sensor 31 may measure all of the three-phase UVW AC currents output from the inverter 10, or may measure the AC current of at least one of the three phases. The frequency of the AC current measured by the current sensor 31 will be referred to as F _AC below.

The low-pass filter 32 has a second cutoff frequency F _C2 that is higher than the first cutoff frequency F _C1 of the high-pass filter 33 (described later) and extracts low-frequency components lower than that frequency from the AC measured by the current sensor 31. The dashed lines in FIG. 2 schematically show the intensity of the AC at each frequency after passing through the low-pass filter 32. The second cutoff frequency F _C2 is higher than the AC frequency F _AC , so higher frequency components are attenuated by the low-pass filter 32, while lower frequency components pass through the low-pass filter 32. High-frequency noise, such as power supply noise, may be constantly superimposed on the AC having the frequency F _AC output from the inverter 10. Therefore, by using the low-pass filter 32 to remove power supply noise and other noise higher than the second cutoff frequency F _C2 , the accuracy of feedback control by the inverter control device 30 is improved. The low-pass filter 32 may be implemented in hardware using a combination of elements such as inductors, capacitors, and resistors, or in software as a digital filter.

The high-pass filter 33 has a first cutoff frequency F _C1 that is higher than the AC frequency F _AC and lower than a second cutoff frequency F _C2 , and extracts higher high-frequency components from the AC measured by the current sensor 31. The high-pass filter 33 may be implemented in hardware using a combination of elements such as inductors, capacitors, and resistors, or may be implemented in software as a digital filter or the like.

In this embodiment, the low-pass filter 32 provided upstream of the high-pass filter 33 has already attenuated frequency components higher than the second cutoff frequency F _C2 , so the high-pass filter 33 selectively extracts a frequency band substantially between the first cutoff frequency F _C1 and the second cutoff frequency F _C2 . As shown in FIG. 2 as "disturbance," disturbances such as random noise may be present or remain in this frequency band. Because such disturbances have frequencies lower than the second cutoff frequency F _C2 , they are not removed by the low-pass filter 32 and may adversely affect the accuracy of feedback control by the inverter control device 30. Therefore, in this embodiment, disturbances that cannot be completely removed by the low-pass filter 32 (hereinafter, also referred to as "high-frequency components," meaning components with frequencies higher than the AC frequency F _AC and/or the first cutoff frequency F _C1 ) are selectively extracted by the high-pass filter 33 and effectively removed by the inverter 34 and adder 35 downstream.

The inverter 34 inverts the sign of the high-frequency component selectively extracted by the high-pass filter 33. The adder 35 adds the high-frequency component inverted by the inverter 34 to the AC current measured by the current sensor 31 and passed through the low-pass filter 32. By adding the high-frequency component whose sign has been inverted by the inverter 34 by the adder 35, the high-frequency component (i.e., the disturbance) is effectively removed from the original AC current.

In this way, the inverter 34 and adder 35 constitute a high-frequency removal unit that subtracts the high-frequency components extracted by the high-pass filter 33 from the AC measured by the current sensor 31. Instead of the inverter 34 and adder 35, the high-frequency removal unit may be constituted by a subtractor that subtracts the high-frequency components selectively extracted by the high-pass filter 33 from the AC measured by the current sensor 31 and passed through the low-pass filter 32. The functionality of the high-frequency removal unit may be implemented in hardware or software.

2 schematically shows the intensity at each frequency of the AC after the disturbance between the first cutoff frequency F _C1 and the second cutoff frequency F _C2 , selectively extracted by the high-pass filter 33, has been removed from the AC (dashed line) after passing through the low-pass filter 32 by the inverter 34 and the adder 35. It can be seen that the disturbance as a high-frequency component that was present after passing through the low-pass filter 32 is effectively removed by the high-pass filter 33, the inverter 34, and the adder 35. As described above, according to this embodiment, not only can steady power supply noise and the like be removed by the low-pass filter 32, but also unsteady or sudden disturbances and the like can be removed by the high-pass filter 33, the inverter 34, and the adder 35, thereby improving the accuracy of feedback control by the inverter control device 30.

The control signal generation unit 36 generates a control signal to be applied to the control electrodes of the switching elements 10P, 10N in the inverter 10 via the driver 37, based on the AC from which the high-frequency components (disturbances) have been subtracted by the adder 35 or the high-frequency removal unit. If the switching elements 10P, 10N are transistors whose gates serve as control electrodes, the control signal generation unit 36 generates a gate signal as the control signal.

The control signal generator 36 may generate a linear control signal that causes the switching elements 10P, 10N to perform switching operations in a linear region (not a saturated region). Such a linear control signal generator may be implemented in hardware, such as a linear amplifier that also has the functionality of the driver 37, or in software. As mentioned above, the low-pass filter 32, high-pass filter 33, inverter 34, and adder 35 can also be implemented in either hardware or software. Therefore, most of the components 32 to 37 of the inverter control device 30, excluding the current sensor 31, may be implemented entirely in hardware, entirely in software, or a combination of hardware and software.

The control signal generating unit 36 may also generate a pulse-width modulation signal (PWM signal) as the control signal to be applied to the control electrodes of the switching elements 10P and 10N. Such a PWM control signal generating unit is typically implemented in software. For this reason, components associated with conventional PWM control signal generating units (e.g., the harmonic phase adjustment unit in Patent Document 1) have generally been implemented in software. As described above, according to this embodiment, the components associated with the PWM control signal generating unit (control signal generating unit 36), such as the low-pass filter 32, high-pass filter 33, inverter 34, and adder 35, may be implemented in software in accordance with conventional practice, but can also be implemented in hardware, thereby increasing the versatility and flexibility of the inverter control device 30.

As described above, the inverter control device 30 according to this embodiment is not only highly versatile and flexible, but can also effectively remove high-frequency components such as disturbances that cannot be removed by the low-pass filter 32, thereby providing highly accurate feedback control for the inverter 10 and, ultimately, the motor 20. For this reason, the inverter control device 30 according to this embodiment is well suited for precision positioning devices that require precise position and speed control, such as stage devices in semiconductor manufacturing equipment that precisely drive tables or stages on which semiconductor wafers or other objects to be processed are placed.

The present invention has been described above based on an embodiment. Various modifications are possible to the combinations of the components and processes in the exemplary embodiment, and it will be obvious to those skilled in the art that such modifications are within the scope of the present invention.

The configuration, action, and functionality of each device and method described in the embodiments can be realized by hardware resources, software resources, or a combination of hardware and software resources. Examples of hardware resources that can be used include processors, ROM, RAM, and various integrated circuits. Examples of software resources that can be used include operating systems, application programs, and other programs.

10 Inverter, 10P Positive potential side switching element, 10N Negative potential side switching element, 20 Motor, 30 Inverter control device, 31 Current sensor, 32 Low pass filter, 33 High pass filter, 34 Inverting unit, 35 Adder, 36 Control signal generating unit, 37 Driver.

Claims (7)

An inverter control device that controls an inverter that converts direct current into alternating current in response to a control signal applied to a control electrode of a switching element,
an AC measuring unit that measures the AC output from the inverter;
a high-pass filter having a first cutoff frequency higher than the frequency of the AC current and extracting high-frequency components higher than the first cutoff frequency from the measured AC current;
a high frequency removal unit that subtracts the extracted high frequency component from the measured AC voltage;
a control signal generating unit that generates a control signal for causing the switching element to perform a switching operation in a linear region based on the AC from which the high-frequency component has been subtracted;
Equipped with
a low-pass filter having a second cutoff frequency higher than the first cutoff frequency and extracting low-frequency components lower than the second cutoff frequency from the measured AC current;
the high-pass filter extracts the high-frequency components higher than the first cutoff frequency from the extracted low-frequency components;
the high frequency removal unit subtracts the extracted high frequency components from the extracted low frequency components;
The control signal generating unit generates the control signal based on the low-frequency component from which the high-frequency component has been subtracted . The inverter control device of claim 1, wherein the control signal generation unit is configured as a linear amplifier. An inverter control device that controls an inverter that converts direct current into alternating current in response to a control signal applied to a control electrode of a switching element,
an AC measuring unit that measures the AC output from the inverter;
a hardware-implemented high-pass filter having a first cutoff frequency higher than the frequency of the alternating current and configured to extract higher frequency components from the measured alternating current;
a hardware-implemented high frequency rejection unit that subtracts the extracted high frequency components from the measured AC voltage;
a control signal generating unit that generates the control signal based on the AC signal from which the high-frequency component has been subtracted;
Equipped with
a low-pass filter having a second cutoff frequency higher than the first cutoff frequency and extracting low-frequency components lower than the second cutoff frequency from the measured AC current;
the high-pass filter extracts the high-frequency components higher than the first cutoff frequency from the extracted low-frequency components;
the high frequency removal unit subtracts the extracted high frequency components from the extracted low frequency components;
The control signal generating unit generates the control signal based on the low-frequency component from which the high-frequency component has been subtracted . The inverter control device described in claim 3, wherein the control signal generation unit generates a pulse-width modulated signal as the control signal based on the AC from which the high-frequency components have been subtracted. The inverter control device described in claim 3, wherein the control signal generation unit generates a linear control signal as the control signal that causes the switching element to perform switching operation in a linear region based on the AC from which the high-frequency components have been subtracted. 1. An inverter control method for controlling an inverter that converts direct current into alternating current in response to a control signal applied to a control electrode of a switching element, comprising:
an AC measuring step of measuring the AC output from the inverter;
a high frequency extraction step of extracting high frequency components higher than a first cutoff frequency that is higher than a frequency of the AC current from the measured AC current;
a high frequency removal step of subtracting the extracted high frequency component from the measured AC voltage;
a control signal generating step of generating a control signal for causing the switching element to perform a switching operation in a linear region based on the AC from which the high-frequency component has been subtracted;
Equipped with
a low-frequency extraction step of extracting low-frequency components lower than a second cutoff frequency higher than the first cutoff frequency from the measured AC voltage;
the high-frequency extraction step extracts the high-frequency components higher than the first cutoff frequency from the extracted low-frequency components;
The high frequency removal step includes subtracting the extracted high frequency components from the extracted low frequency components;
The inverter control method includes generating the control signal based on the low-frequency component from which the high-frequency component has been subtracted, in the control signal generating step . An inverter control program for controlling an inverter that converts direct current into alternating current in response to a control signal applied to a control electrode of a switching element,
an AC measuring step of measuring the AC output from the inverter;
a high frequency extraction step of extracting high frequency components higher than a first cutoff frequency that is higher than a frequency of the AC current from the measured AC current;
a high frequency removal step of subtracting the extracted high frequency component from the measured AC voltage;
a control signal generating step of generating a control signal for causing the switching element to perform a switching operation in a linear region based on the AC from which the high-frequency component has been subtracted;
on the computer ,
further causing the computer to execute a low-frequency extraction step of extracting, from the measured AC current, low-frequency components lower than a second cutoff frequency that is higher than the first cutoff frequency;
the high-frequency extraction step extracts the high-frequency components higher than the first cutoff frequency from the extracted low-frequency components;
The high frequency removal step includes subtracting the extracted high frequency components from the extracted low frequency components;
The control signal generating step generates the control signal based on the low-frequency component from which the high-frequency component has been subtracted .