Magnetic levitation control device and magnetic levitation motor system based on a global single clock source

Abstract

The present invention relates to a magnetic levitation control device and a magnetic levitation motor system based on a global single clock source. The magnetic levitation control device includes a sensor module, a power amplification module, an A / D conversion module, a magnetic levitation motor, and a magnetic levitation control unit. The clock signal of the magnetic levitation control device is generated based on a global single clock source and includes a sensing clock for detection by the sensor module, a sampling clock for sampling by the A / D conversion module, and a power amplification clock for driving the power amplification module. The sensor module is configured to detect control data for the magnetic levitation motor and output a sensor signal. The A / D conversion module is configured to convert the sensor signal into a sampled signal. The magnetic levitation control unit is configured to perform data processing on the sampled signal to generate a power amplification signal. The power amplification module is configured to generate a PWM signal and to excite the electromagnetic coil in the magnetic levitation motor based on the PWM signal. The present invention can improve the system's signal-to-noise ratio and interference immunity, eliminates the need for an additional synchronization module, and has a simple and low-cost system structure.

Description

Technical Field

[0001] The present invention belongs to the technical field of magnetic levitation motors, and particularly relates to a magnetic levitation control device and a magnetic levitation motor system based on a global single clock source.

Background Art

[0002] A magnetic levitation motor is a magnetic levitation rotary drive device that uses magnetic field force to levitate a rotor so that there is no mechanical contact between the rotor and the stator. The magnetic levitation motor may be a magnetic bearing motor, a bearingless motor, a bearingless slice motor, etc.

[0003] A magnetic bearing motor, also called a magnetic bearing, is a combination of a motor for rotary drive and an axial magnetic bearing and / or a radial magnetic bearing and / or an axial-radial hybrid magnetic bearing, etc., and is not an integrally integrated motor.

[0004] A bearingless motor is a motor that integrally integrates the rotation function and the levitation function of the motor. In a bearingless motor, a winding for generating an excitation magnetic field is further wound around a winding for generating a rotation drive magnetic field. Due to the interaction of these two magnetic fields, the balance of the original drive magnetic field is disrupted to generate a radial force acting on the rotor, and the levitation of the rotor is realized by controlling the radial force of the motor. Compared with a magnetic bearing motor, the bearingless motor has the magnetic levitation winding wound around the stator and does not require additional radial space, thus overcoming to some extent the disadvantages of the magnetic bearing, such as large volume and high cost. A conventional bearingless motor is usually composed of two bearingless motors and one axial magnetic bearing to levitate the motor rotor in five degrees of freedom.

[0005] The bearingless slice motor is a special type of bearingless motor that retains the advantages of a bearingless motor while having an extremely small ratio of axial length to diameter of the rotor, resulting in a slice-like shape. By eliminating the axial magnetic bearing, bearingless technology enables rotor rotation and radial active levitation, while a magnetic circuit composed of a mechanical structure enables passive levitation in three degrees of freedom other than radial and rotor rotation. It features high cleanliness, no deposition, no particles, no dynamic seals, and superior performance, making it promising for a wide range of applications in ultra-clean drive fields such as biochemistry, medicine, and semiconductor manufacturing.

[0006] Unless otherwise specified, a magnetic levitation motor is a magnetic levitation rotary drive device that uses magnetic field force to levitate the rotor, and has no mechanical contact between the rotor and the stator.

[0007] Compared to conventional motors using contact-type mechanical bearings, magnetic levitation motors require more degrees of freedom control. Therefore, more sensors need to be installed within the motor body. Various sensors and sensor circuits are collectively referred to here as "sensor assemblies," and various adjustment circuits that adjust and process sensor signals, including control data output from the sensor assemblies, are collectively referred to here as "signal adjustment modules." The sensor assemblies and signal adjustment modules are configured as sensor modules, enabling real-time detection of control data for the magnetic levitation motor. Control data may include, for example, rotor displacement data, rotor angle data (rotor rotation speed data), or electromagnetic coil current data. Using the control data as feedback, the control host or control device of the magnetic levitation motor generates a control signal for the power amplifier, which is the execution means, based on the control policy. The power amplifier controls the levitation and / or rotation of the rotor by outputting current to excite the electromagnetic coils in the stator portion of the magnetic levitation motor. The power amplifier is also called a power amplifier circuit, and an example is a PWM power amplifier. A power amplifier may be an output stage or output stage circuit including a PWM generator or PWM circuit, or it may simply be an output stage or output stage circuit with amplified power. Here, various power amplifiers including an output stage or output stage circuit are collectively referred to as a "power amplifier module".

[0008] The output stage of the power amplifier in a control device for a magnetic levitation motor includes multiple switching elements, such as MOS transistors and IGBTs. When these switching elements switch, spike-like noise is generated in the system. Due to the requirement for compact motor structure, the electromagnetic coils for rotational and / or levitation control and the sensors for detecting motor control data are usually configured spatially close together in a magnetic levitation motor. However, because the current signal flowing through the electromagnetic coil contains spike-like noise, it easily interferes with sensor detection and the sampling of its signal adjustment circuit, resulting in a decrease in the signal-to-noise ratio of the entire control system and poor interference immunity. To solve the interference problem caused by spike-like noise, the A / D conversion module and the power amplifier are synchronized by a synchronization signal transmitted from a synchronization module, thereby avoiding interference from spike-like noise caused by the switching elements in the power amplifier. However, this synchronization method requires the addition of a synchronization module to the system, which complicates the system hardware structure and increases costs. On the other hand, this synchronization method introduces errors in phase locking between the power signal (PWM signal) of the power amplifier and the sampling signal of the A / D conversion module, affecting the accuracy of displacement detection. Furthermore, errors exist in the mechanical assembly of the motor (e.g., the assembly of windings, core, and sensors), and errors also exist in the electronic components themselves, resulting in large variations in mass-produced conventional magnetic levitation motor products. [Overview of the project]

[0009] To solve the above technical problems, the present invention proposes a magnetic levitation control device and magnetic levitation motor system based on a global single clock source that can improve the system's signal-to-noise ratio and interference immunity, eliminate the need for additional synchronization modules, and have a simple system structure and low cost.

[0010] In one aspect of the present invention, a magnetic levitation control device based on a global single clock source is provided, which includes a sensor module, a power amplification module, an A / D conversion module, and a magnetic levitation control unit, wherein the clock signal of the magnetic levitation control device is generated based on a global single clock source, and the clock signal includes a sensing clock for detection by the sensor module, a sampling clock for sampling by the A / D conversion module, and a power amplification clock for driving the power amplification module. The sensor module is configured to detect control data for the magnetic levitation motor and output a sensor signal based on the sensing clock. The A / D conversion module is configured to convert the sensor signal into a sampling signal based on the sampling clock. The magnetic levitation control unit is configured to perform data processing on the sampling signal to generate a power amplification signal. The power amplification module is configured to generate a PWM signal based on the power amplification signal and the power amplification clock, and to excite the electromagnetic coil in the magnetic levitation motor based on the PWM signal.

[0011] Furthermore, the magnetic levitation control device further includes a clock distribution module that generates a clock signal including a sensing clock, a sampling clock, and a power amplification clock based on a reference clock of a global single clock source.

[0012] Furthermore, the clock distribution module includes a frequency divider module equipped with multiple frequency dividers, each of which performs frequency division on a reference clock from a single global clock source to generate multiple divided clocks, and the clock signal includes multiple divided clocks, which include a sensing clock, a sampling clock, and a power amplification clock.

[0013] Furthermore, the clock distribution module further includes a frequency multiplier that generates a multiplied clock by multiplying a reference clock from a global single clock source, and multiple frequency dividers perform frequency division based on the multiplied clock.

[0014] Furthermore, the clock distribution module includes multiple frequency multipliers, one of which is connected to a global single clock source to generate a divided clock, while the other dividers correspond one-to-one with the other frequency multipliers. Each frequency multiplier multiplies a reference clock from the global single clock source to generate a multiplied clock, and the dividers perform frequency division based on the multiplied clocks generated by the corresponding frequency multipliers.

[0015] Furthermore, the clock distribution module further includes a phase shift module, the phase shift module includes multiple phase shifters that correspond one-to-one with multiple frequency dividers, the phase shifters adjust the phase of the divided clocks from the corresponding frequency dividers, and the clock signal includes the multiple divided clocks after phase shift adjustment.

[0016] Furthermore, the magnetic levitation control device further includes a communication port for communication connections to write frequency division and / or phase shift values.

[0017] Furthermore, the sensor module includes a sensor assembly and a signal conditioning module, the sensing clock includes a sensor clock and a signal conditioning clock, the sensor assembly is configured to detect control data for the magnetic levitation motor based on the sensor clock and generate a sensor signal containing the control data, and the signal conditioning module is configured to adjust and process the sensor signal containing the control data based on the signal conditioning clock and generate the adjusted sensor signal.

[0018] Furthermore, the sensor assembly includes a displacement sensor for detecting rotor displacement data of the magnetic levitation motor, and / or a position angle sensor for detecting rotor angle data of the magnetic levitation motor, and / or a current sensor for detecting current data of the electromagnetic coil of the magnetic levitation motor, and the sensor signals include a rotor displacement signal, and / or a rotor angle signal, and / or a current signal.

[0019] Furthermore, one of the multiple frequency dividers and its corresponding phase shifter are configured to generate a sensor clock, another of the multiple frequency dividers and its corresponding phase shifter are configured to generate a signal adjustment clock, or one of the multiple frequency dividers and its corresponding phase shifter are configured to generate an intermediate sensing clock, and the phase shift module further includes a secondary phase shifter that performs phase shift processing on the intermediate sensing clock to generate a sensor clock and a signal adjustment clock.

[0020] Furthermore, the magnetic levitation control device further includes a power supply, the clock signal further includes a power supply clock, and the power switch of the power supply is based on the power supply clock.

[0021] Furthermore, the magnetic levitation control unit is an integrated magnetic levitation and rotation control unit. Based on the rotor displacement data and rotor angle data of the magnetic levitation motor, the integrated magnetic levitation and rotation control unit calculates the rotational current component for rotational control of the magnetic levitation motor and the levitation current component for levitation control of the magnetic levitation motor, and then performs current synthesis on the rotational current component and the levitation current component to generate a current command signal.

[0022] Furthermore, the power amplification module includes a PWM generator and an output stage, the PWM generator generating a PWM signal for PWM control of the output stage based on the power amplification clock and power amplification signal.

[0023] Furthermore, the PWM generator is integrated into the magnetic levitation rotation integrated control unit.

[0024] Furthermore, the clock distribution module is implemented based on an FPGA, the magnetic levitation control unit is implemented based on a DSP, the clock signal further includes the system clock, and the DSP's system control is performed based on the system clock.

[0025] Furthermore, both the clock distribution module and the magnetic levitation control unit are implemented based on FPGAs, MCUs, or DSPs.

[0026] Furthermore, the A / D conversion module is built into the FPGA, MCU, or DSP, or the A / D conversion module is externally attached to the FPGA, MCU, or DSP.

[0027] In another aspect of the present invention, a magnetic levitation motor system based on a global single clock source is provided, and the magnetic levitation motor system includes a magnetic levitation motor and the above magnetic levitation control device.

[0028] Furthermore, the magnetic levitation motor is a magnetic bearing motor, a bearingless motor, or a bearingless slice motor.

[0029] The above technical solution of the present invention has the following advantages compared with the prior art. The present invention proposes a magnetic levitation control device and a magnetic levitation motor system based on a global single clock source. By making the clock signals of each component in the magnetic levitation control device derived from the global single clock source, the sensing clock for detection of the sensor module, the sampling clock for sampling of the A / D conversion module, and the power amplification clock for driving of the power amplification module are configured as in-phase clocks (the clock signal frequencies may be different, but the active edges of the clocks are aligned). Thereby, the active edges (clock edges) of each clock signal in the magnetic levitation motor system are accurately aligned. Furthermore, on the basis that the active edges are aligned, the delay time between related signals is accurately controlled and adjusted, that is, it is ensured that the phase or phase difference between related signals between each component is definite. Thereby, noise and interference caused by the power amplification module and other components in the process of sensor detection or A / D conversion are avoided, the signal-to-noise ratio and anti-interference performance of the system can be improved, there is no need to add a synchronization module, the system structure is simple and the cost is low.

[0030] To understand the content of the present invention more clearly, the present invention will be described in more detail below with reference to specific embodiments and drawings of the present invention.

Brief Description of the Drawings

[0031] [Figure 1] FIG. 6 is a schematic configuration diagram of an embodiment of a magnetic levitation control device and a magnetic levitation motor system based on a global single clock source according to the present invention. [Figure 2] FIG. 9 is a schematic configuration diagram of an embodiment of a clock distribution module according to the present invention. [Figure 3] FIG. 12 is a schematic configuration diagram of another embodiment of a clock distribution module according to the present invention. [Figure 4] FIG. 15 is a schematic configuration diagram of another embodiment of a clock distribution module according to the present invention. [Figure 5] FIG. 18 is a schematic configuration diagram of another embodiment of a clock distribution module according to the present invention. [Figure 6] FIG. 21 is a schematic configuration diagram of another embodiment of a magnetic levitation control device and a magnetic levitation motor system based on a global single clock source according to the present invention.

Modes for Carrying Out the Invention

[0032] In order to enable those skilled in the art to better understand and implement the present invention, the present invention will be further described below with reference to the drawings and specific embodiments. However, the described embodiments do not limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without using inventive capabilities also belong to the protection scope of the present invention.

[0033] In the description of this invention, directions or positional relationships expressed by terms such as “up,” “down,” “inside,” and “outside” are based on the drawings and are for the convenience and brevity of describing the invention. They do not expressly or implicitly indicate that the device or element in question necessarily has, is configured in, or is operated in a particular direction, and should be understood not to limit the invention. The terms “includes,” “has,” and their synonyms in the specification, claims, and drawings of this invention are intended to cover non-exclusive inclusion. For example, a system, product, or equipment including a series of units is not necessarily limited to these specified elements and may include other elements that are not specified or are specific to such product or equipment.

[0034] In conventional technology, the output stage of the power amplifier in a magnetic levitation motor control system includes multiple switching elements, such as MOS transistors and IGBTs. When these switching elements switch, spike-like noise is generated in the system. Due to the requirement for compact motor structure, the electromagnetic coil for rotation control and / or levitation control and the sensor for detecting motor control data are usually configured spatially close together in a magnetic levitation motor. However, because the current signal flowing through the electromagnetic coil contains spike-like noise, it easily interferes with sensor detection and the sampling of its signal adjustment circuit, resulting in a decrease in the signal-to-noise ratio of the entire control system and poor interference immunity. To solve the interference problem caused by spike-like noise, the A / D conversion module and the power amplifier can be synchronized using a synchronization signal transmitted from a synchronization module, thereby avoiding interference from spike-like noise caused by the switching elements in the power amplifier. However, this synchronization method requires the addition of a synchronization module to the system, which complicates the system hardware structure and increases costs. On the other hand, this synchronization method introduces errors in phase locking between the power signal (PWM signal) of the power amplifier and the sampling signal of the A / D conversion module, affecting the accuracy of displacement detection. Furthermore, errors exist in the mechanical assembly of the motor (e.g., the assembly of windings, core, and sensors), and errors also exist in the electronic components themselves, resulting in large variations in mass-produced conventional magnetic levitation motor products.

[0035] To solve the above technical problems, the present invention proposes a magnetic levitation control device based on a global single clock source. As shown in Figure 1, this magnetic levitation control device includes a sensor module, a power amplification module, an A / D conversion module, and a magnetic levitation control unit. The clock signal of the magnetic levitation control device is generated based on a global single clock source and includes a sensing clock for detection by the sensor module, a sampling clock for sampling by the A / D conversion module, and a power amplification clock for driving the power amplification module. The sensor module is configured to detect control data for the magnetic levitation motor and output a sensor signal based on the sensing clock. The A / D conversion module is configured to convert the sensor signal into a sampling signal based on the sampling clock. The magnetic levitation control unit is configured to perform data processing on the sampling signal to generate a power amplification signal. The power amplification module is configured to generate a PWM signal based on the power amplification signal and the power amplification clock, and to excite the electromagnetic coil in the magnetic levitation motor based on the PWM signal.

[0036] This invention makes the clock signals of each component in the magnetic levitation control device originate from a single global clock source. By configuring the sensing clock for detection in the sensor module, the sampling clock for sampling in the A / D conversion module, and the power amplification clock for excitation in the power amplification module as in-phase clocks, the active edges (clock edges) of each clock signal in the magnetic levitation motor system are precisely aligned. Furthermore, with the active edges aligned, the delay time between related signals is precisely controlled and adjusted, ensuring that the phase or phase difference between related signals between each component is deterministic. This avoids noise and interference from the power amplification module during the sensor detection and A / D conversion processes. For example, with the active edges aligned, the sampling time of the A / D conversion module can be controlled to avoid noise and interference from other components, improving the system's signal-to-noise ratio and interference immunity. There is no need to add a synchronization module, resulting in a simple system structure and low cost.

[0037] In-phase clocks refer to two or more clocks whose clock signal frequencies may be the same or different, but whose active edges are aligned. The active edge can be a rising edge or a falling edge. Phase, also called "phase time," refers to the delay time between a clock signal and an ideal signal (e.g., a reference clock) at their corresponding active moment (generally a rising or falling edge); in other words, phase is a time delay. For example, if there is one slow clock and one fast clock, their clock frequencies may be different, but the clock edge of the slow clock is always aligned with the clock edge of the fast clock, and the phases of the two clocks coincide at the clock edge of the slow clock. In this invention, each clock signal is based on a global single clock source, and its purpose is to provide each component with multiple clock signals with aligned active edges, thereby ensuring that the phase relationship is deterministic when accurately identifying the phase or phase difference of each related signal and avoiding noise and interference, thereby solving the problem of not being able to avoid noise and interference due to uncertainty in the phase relationship. The clock frequencies of each clock signal may be the same or different; for example, the clock frequency of the sensing clock for detection in a sensor module may be different from the clock frequency of the power amplification clock for a power amplification module. If the clock frequencies of the two clock signals are different and the active edges of the two clock signals are not aligned, errors will occur in the phase lock between other signals generated based on those clock signals. For example, if there is an error in the phase lock between the PWM signal of the power amplification module and the sampling signal of the A / D conversion module, the accuracy of displacement detection will be affected. The magnetic levitation control device according to the present invention is based on a global single clock source and can ensure that the active edges (clock edges) of each clock signal in the magnetic levitation motor system are precisely aligned. In addition to the alignment of the active edges, the delay time between each related signal is precisely controlled and adjusted to avoid noise and interference from the power amplification module and other components during the sensor detection and A / D conversion processes.

[0038] As shown in Figures 1 and 6, the power amplification module is configured to generate a PWM signal based on a power amplification signal and a power amplification clock, and to excite the electromagnetic coils in a magnetic levitation motor based on the PWM signal. That is, the power amplification module functions as an execution means for a magnetic levitation control device, outputting current to excite the electromagnetic coils in the stator portion of the magnetic levitation motor, thereby achieving rotor levitation and / or rotation control. Here, the electromagnetic coil may be a coil winding for rotation control of a bearingless motor, a coil winding for levitation control, or a coil winding having both functions. It may also be a motor coil for motor rotation of a magnetic bearing motor, or an electromagnet coil for a magnetic bearing. The power amplification module is also called a power amplification device or power amplification circuit, and may be an output stage or output stage circuit including a PWM generator or PWM circuit, or simply an output stage or output stage circuit, or may further include an isolated drive circuit, etc. In this invention, various power amplification devices including an output stage or output stage circuit are collectively referred to as "power amplification modules". In one embodiment, the power amplification module includes a PWM generator and an output stage, and Figure 1 shows only the entire power amplification module. The PWM generator, also called a PWM circuit, generates a PWM signal for PWM control of the output stage based on a power amplification clock and power amplification signal. In another embodiment, as shown in Figure 6, the PWM generator is integrated into a magnetic levitation-rotation integrated control unit, and the magnetic levitation-rotation integrated control unit and the PWM generator constitute the magnetic levitation-rotation integrated control unit. Then, only one power amplification module is needed corresponding to the magnetic levitation-rotation integrated control unit, enabling levitation and rotation control by a single control system and simplifying the hardware structure. In another embodiment, the power amplification module includes an output stage, and the magnetic levitation-rotation integrated control unit is configured to perform data processing on the sampled signal and generate a PWM signal based on a power amplification clock and power amplification signal to PWM control the power amplification module, and Figure 6 shows only the output stage.In the principle of a PWM generator, the power amplification clock is used as a reference clock frequency to determine the period of the PWM waveform; in other words, the power amplification clock controls the counter count. The counter increases its count value in response to the reference clock frequency; that is, the counter's count range determines the period of the PWM signal. The counter's count range can be set by configuring the counter's count value. The comparator circuit generates a PWM signal according to the counter's count value; that is, the comparator's comparison value determines the duty cycle of the PWM signal. The comparator's comparison value can be set by configuring the comparator's reference voltage.

[0039] As shown in Figures 1 and 2, the sensor module is configured to detect control data for the magnetic levitation motor based on a sensing clock and to output a sensor signal. Because the magnetic levitation motor requires control of more degrees of freedom, more sensors are installed within the motor body. Various sensors and sensor circuits are collectively referred to here as the "sensor assembly," and various adjustment circuits that adjust and process the sensor signals, including the control data output from the sensor assembly, are collectively referred to here as the "signal adjustment module." As shown in Figure 1, the signal adjustment module is usually integrated into the magnetic levitation control device. In other embodiments, the signal adjustment module as a component of the magnetic levitation control device may be provided separately from the main body of the magnetic levitation control device. For example, it may be provided as an independent signal adjustment box, and the signal adjustment box may be connected independently of the magnetic levitation motor and the magnetic levitation control device to the sensor assembly in the magnetic levitation motor and the A / D conversion module in the magnetic levitation control device. The sensor assembly and signal adjustment module constitute the sensor module, and the sensor module can detect the control data of the magnetic levitation motor in real time. The control data may include, for example, rotor displacement data, rotor angle data (rotor rotation speed data), or electromagnetic coil current data. Preferably, as shown in Figures 1 and 2, the sensor module includes a sensor assembly and a signal adjustment module, the sensing clock includes a sensor clock and a signal adjustment clock, the sensor assembly is configured to detect control data for the magnetic levitation motor based on the sensor clock and generate a sensor signal containing the control data, and the signal adjustment module is configured to adjust and process the sensor signal containing the control data based on the signal adjustment clock to generate an adjusted sensor signal.

[0040] The present invention does not limit the type of sensor and sensor circuit of the sensor assembly. For example, the sensor assembly includes a displacement sensor for detecting rotor displacement data of a magnetic levitation motor and / or a position angle sensor for detecting rotor angle data of a magnetic levitation motor and / or a current sensor for detecting current data of the electromagnetic coil of a magnetic levitation motor, and the sensor signals include a rotor displacement signal and / or a rotor angle signal and / or a current signal.

[0041] The following explanation uses a sensor assembly as an example, where the sensor assembly is a displacement sensor for detecting rotor displacement data of a magnetic levitation motor, to describe the principle of detecting, adjusting, and processing rotor displacement data using a sensor module.

[0042] Displacement sensors detect rotor displacement during the operation of a magnetic levitation motor. Currently, sensors used for displacement detection are generally inductance or eddy current displacement sensors, but are not limited to these. Taking an eddy current displacement sensor as an example, it detects minute displacements using the principle of the eddy current effect. When an excitation source or excitation signal applies a high-frequency alternating current to the sensor coil, an alternating magnetic field and an induced electric field are generated in the coil. When a metal conductor approaches the coil, the induced electric field generates induced eddy currents on the surface of the metal conductor. The eddy magnetic field generated by the eddy currents is in the opposite direction to the coil magnetic field and cancels out part of the coil magnetic field, so the impedance of the sensor coil changes. When the distance between the metal conductor and the sensor coil changes, the impedance of the sensor coil also changes accordingly, and therefore the distance between the metal conductor and the sensor coil is measured based on the impedance. In principle, by providing one eddy current displacement sensor for each degree of freedom direction, the displacement of the rotor in that degree of freedom direction can be detected. However, in actual measurements, the accuracy and stability of displacement measurements are susceptible to temperature drift, probe manufacturing accuracy, and workpiece mounting accuracy. Therefore, as one preferred embodiment, a differential signal and an eddy current displacement sensor are combined to detect the relative displacement in the rotor stator. By using two sensor coils with the same winding method and ensuring that the two sensor coils are at the same ambient temperature in the stator, adverse effects due to temperature drift can be effectively suppressed. Furthermore, by using a differential signal to determine relative displacement rather than absolute displacement, the influence of manufacturing accuracy on the measurement can be reduced. Based on the differential displacement sensor, rotor displacement detection can be further improved by utilizing the LC resonance principle of a resonant circuit to enhance the signal-to-noise ratio and interference immunity of the sensor detection.

[0043] Since the impedance change of a coil is generally small, accurately measuring minute impedance changes is key to demodulating eddy current displacement sensors. Conventional techniques generally employ amplitude detection, extracting amplitude information from the signal by rectifying and filtering the terminal voltage of the sensor coil. While this method is simple and easy to implement, the small impedance change of the coil necessitates amplification of minute voltage changes in the coil using a high-gain amplifier. In this case, unwanted interference signals are also amplified, reducing the signal-to-noise ratio. Furthermore, amplitude detection is highly susceptible to device temperature drift, requiring the addition of a temperature drift compensation circuit, significantly increasing hardware costs. Therefore, the eddy current signal demodulation circuit according to the present invention is implemented by phase discrimination. The core of phase discrimination involves using an analog multiplier to multiply the voltage signal at the equivalent inductance of the sensor coil by the demodulated signal orthogonal to the excitation signal of the sensor coil, filtering it, and then obtaining a low-frequency signal containing phase information. The advantage is that it utilizes the orthogonality of the excitation and demodulated signals to eliminate the influence of unrelated frequency signals, resulting in excellent interference immunity. Furthermore, the phase signal is more sensitive because the change in accordance with the impedance change of the excitation coil is more pronounced. In the present invention, when detecting rotor displacement, the sensor module includes a sensor assembly and a signal conditioning module, and the sensing clock includes a sensor clock and a signal conditioning clock. The sensor assembly is, for example, an eddy current displacement sensor such as a differential displacement sensor. The differential displacement sensor detects the displacement data of the rotor of a magnetic levitation motor based on the sensor clock and generates a sensor signal containing the displacement data. The sensor clock originates from a global single clock source and can be used as an excitation signal to excite the sensor coil of the eddy current displacement sensor, either directly or after amplified processing. The signal conditioning module is a phase-locked amplifier circuit, which adjusts and processes the sensor signal containing the displacement data based on the signal conditioning clock to generate the adjusted sensor signal.The signal conditioning clock originates from a single global clock source, the same clock source as the sensor clock, and a simple phase division / shift process can be used to obtain an orthogonal reference signal of the same frequency for the phase-locked amplifier circuit. Thus, both the excitation signal and demodulation signal for the signal conditioning module originate from a single global clock source, and their phase difference is deterministic and easy to implement, which effectively improves the sensitivity and interference immunity of the sensor detection. In other embodiments, both amplitude detection and phase discrimination may be used.

[0044] In the above embodiment, the detection of rotor displacement data and signal conditioning were explained using an eddy current sensor as an example. However, the invention is not limited to these. For example, position and angle sensors for detecting rotor angle data of a magnetic levitation motor, such as a Hall sensor, and current sensors for detecting current data of the electromagnetic coil of a magnetic levitation motor, such as a Hall sensor, can also generate excitation signals for sensors and demodulated signals for signal conditioning circuits based on a global single clock source. Furthermore, a deterministic phase relationship between different sensors can be ensured based on a global single clock source. For example, if a magnetic levitation motor simultaneously includes a displacement sensor, a position and angle sensor, and a current sensor, a deterministic phase relationship exists between the different sensor signals of each sensor detection circuit, thereby reducing mutual noise interference between sensing detection circuits. The essence of a signal conditioning circuit is a multiplier, and since a multiplier can be implemented by an analog switch, noise generated during the switching process may affect other sensors. A global single clock source ensures a deterministic phase or phase difference between the signals of each sensor module, thereby avoiding noise generated between them during the signal conditioning process and improving the system's signal-to-noise ratio and interference immunity.

[0045] As shown in Figure 1, the A / D conversion module is configured to convert the sensor signal into a sampled signal based on a sampling clock. The A / D conversion module, also called an ADC or A / D converter, samples the rotor displacement signal, rotor angle signal, and electromagnetic coil current signal of the rotor detected by the sensor module, and performs A / D conversion on the rotor displacement signal, rotor angle signal, and current signal to generate a rotor displacement digital signal, a rotor angle digital signal, and a current digital signal. The output terminal of the A / D conversion module is connected to the input terminal of the magnetic levitation control unit (including the control algorithm). When the switching element of the power amplifier module switches during sampling by the A / D conversion module, the sampled signal of the A / D conversion module is affected by spike-like noise interference caused by the switching of the switching element. As a result, errors occur in the sampling of the A / D conversion module, which can lead to a crash of the digital control system. When the PWM signal of the power amplifier module and the sampled signal of the A / D conversion module are sampled by the A / D conversion module, errors in the phase lock will affect the accuracy of sensor detection. Therefore, the present invention controls the sampling time of the A / D conversion module using a sampling clock from a global single clock source as a control signal. The sampling clock of the A / D conversion module, the power amplification clock of the power amplification module, and the sensing clock of the sensor module all originate from the same clock source and have a deterministic phase difference relationship. Therefore, on the one hand, it is possible to eliminate the phase lock error between the PWM signal of the power amplification module and the sampling signal of the A / D conversion module, ensure a deterministic positional relationship between the active edge (clock edge) of the sampling signal of the A / D conversion module and the active edge of the PWM signal of the power amplification module, and improve the accuracy of sensor detection. On the other hand, it is possible to avoid switching the switching elements of the power amplification module during the sampling time of the A / D conversion module, avoid interference from spike-like noise caused by the switching elements in the power amplification device, and improve the system's signal-to-noise ratio and interference immunity.

[0046] As shown in Figures 1 and 2, in the magnetic levitation control device according to the present invention, a global single clock source is used to generate a reference clock. In one preferred embodiment, the global single clock source may be a quartz crystal oscillator (Xtal).

[0047] As shown in Figures 1 and 2, the clock signal of the magnetic levitation control device is generated based on a global single clock source, and the clock signal includes a sensing clock for detection of the sensor module, a sampling clock for sampling of the A / D conversion module, and a power amplification clock for driving the power amplification module. Thus, the clock signals of the sensor module, A / D conversion module, and power amplification module all originate from a global single clock source, that is, they are from the same clock source. Therefore, a deterministic phase difference can be ensured between each related signal without providing a synchronization module. The same clock source can be realized by a clock topology. Preferably, the magnetic levitation control device according to the present invention further includes a clock distribution module that generates a clock signal including a sensing clock, a sampling clock, and a power amplification clock based on a reference clock of a global single clock source. However, the clock signal generated by the clock distribution module can also be extended according to the requirements of the global clock for the entire system, for example, a power supply clock, a system clock, etc., in the technical proposal below. Figure 2 shows a power supply clock, and other extensions are indicated by the leader (...). By using a clock distribution module to unify and distribute the reference clock from a single global clock source, the global clock requirements of each component can be met.

[0048] As shown in Figure 2, in one embodiment, the clock distribution module includes a frequency divider module with multiple frequency dividers, each of which divides a reference clock from a single global clock source to generate multiple divided clocks, and the clock signal includes multiple divided clocks, which include a sensing clock, a sampling clock, and a power amplification clock. Since a single crystal oscillator has only one natural frequency, it can be expanded to multiple frequencies by dividing it. Therefore, it is not necessary to distribute one crystal oscillator for each frequency. For example, the initial signal of a crystal oscillator becomes 1 / N of the original frequency after N division. The function of the clock distribution module can be realized by generating multiple divided clocks with specific frequencies, such as a sensing clock, a sampling clock, and a power amplification clock, using multiple frequency dividers. In one preferred embodiment, each frequency divider in Figure 2 is based on a single global clock source. The frequency divider module shown in Figure 2 includes a first frequency divider, a second frequency divider, a third frequency divider, a fourth frequency divider, and a fifth frequency divider, with extensions of other frequency dividers indicated by a leader (...). In other embodiments, extensions of frequency dividers are similarly indicated by leaders. The first frequency divider performs frequency division based on a reference clock to generate a signal adjustment clock for signal adjustment. The second frequency divider performs frequency division based on a reference clock to generate a sensor clock for sensor excitation. The third frequency divider performs frequency division based on a reference clock to generate a sampling clock for sampling the A / D conversion module. The fourth frequency divider performs frequency division based on a reference clock to generate a power amplification clock for driving the power amplification module. The fifth frequency divider performs frequency division based on a reference clock to generate a power clock for the power switch of the power supply. In this embodiment, five types of clock signals for the magnetic levitation control device are exemplified, but the invention is not limited to these, and all clock signals for the entire magnetic levitation control device can be obtained from a global single clock source through the extensions of the frequency divider module.In this embodiment, the frequency divider module includes five frequency dividers, each independently generating a clock signal based on a single global clock source. However, it is not limited to this, and in other embodiments, a different clock signal can be generated by re-dividing or phase shifting based on a single frequency divider.

[0049] As shown in Figure 3, in one embodiment, the clock distribution module further includes a frequency multiplier that multiplies a reference clock from a global single clock source to generate a multiplied clock, and multiple frequency dividers perform frequency division based on the multiplied clock. By providing a frequency multiplier before the division, the oscillation frequency of the crystal oscillator can be increased, providing a variety of frequency options for each clock signal and improving the system's flexibility. As shown in Figure 4, in another embodiment, the clock distribution module further includes multiple frequency multipliers, the multiple frequency multipliers shown in Figure 4 include frequency multiplier A, frequency multiplier B, frequency multiplier C, and frequency multiplier D, and extensions of other frequency multipliers are denoted by a leader (...). In other embodiments, extensions of frequency multipliers are similarly denoted by a leader. One of the frequency dividers (Divider A) is connected to a global single clock source to generate one divided clock, while other dividers such as Divider B, Divider C, Divider D, and Divider F correspond one-to-one with multiple frequency multipliers. Each frequency multiplier multiplies the reference clock from the global single clock source to generate a multiplied clock, and the dividers perform frequency division based on the multiplied clock generated by the corresponding frequency multiplier. In this way, by connecting multiple frequency multipliers to a global single clock source, it is possible to obtain multiple multiplied clocks of a wider variety, and multiple dividers can generate multiple divided clocks with specific frequencies, such as sensing clocks, sampling clocks, power amplification clocks, and power supply clocks.

[0050] As shown in Figures 2, 3, and 4, in one embodiment, the clock distribution module further includes a phase shift module, the phase shift module includes a plurality of phase shifters that correspond one-to-one with a plurality of frequency dividers, the phase shifters adjust the phase of the divided clocks from the corresponding frequency dividers, and the clock signal includes the plurality of divided clocks after phase shift adjustment. In Figures 2 and 3, the plurality of phase shifters are the first phase shifter, the second phase shifter, the third phase shifter, the fourth phase shifter, and the fifth phase shifter, each corresponding one-to-one with the first frequency divider, the second frequency divider, the third frequency divider, the fourth frequency divider, and the fifth frequency divider, respectively. In Figure 4, the plurality of phase shifters are phase shifter A, phase shifter B, phase shifter C, phase shifter D, and phase shifter F, each corresponding one-to-one with frequency dividers A, B, C, D, and F, respectively. However, this is not limited to these examples, and in other embodiments, the phase shifter corresponding to the frequency divider can be omitted when phase shift adjustment is not required. Conventional magnetic levitation motor products have large variations in mass production due to errors in the mechanical assembly of the motor (e.g., assembly of windings with the core or sensors) and errors in the electronic components themselves. By providing multiple phase shifters that correspond one-to-one with multiple frequency dividers, the phase of each clock signal can be adjusted. On the other hand, phase adjustment allows for precise alignment of the clock edges of clock signals of specific frequencies. On the other hand, phase adjustment reduces the impact of errors in the mechanical assembly of the motor and / or errors in the electronic components themselves on sensor detection, thereby improving the accuracy of system detection and the mass production consistency of the product.

[0051] As shown in Figure 1, in one embodiment, the magnetic levitation control device further includes a communication port for communication connections, which is used to write the division and phase shift values. By writing the division and phase shift values ​​via the communication port, the division and phase shift by the clock distribution module can be adjusted online, eliminating the influence of errors in the mechanical assembly of the motor and / or errors in the electronic components themselves on sensor detection, thereby improving the accuracy of system detection and the mass production consistency of the product. The communication port may be located on the circuit board of the control system as a port for communication connections.

[0052] As shown in Figure 1, in one embodiment, the magnetic levitation control device further includes a power supply, the clock signal further includes a power supply clock, and the power switch of the power supply is based on the power supply clock. In this way, the power supply clock is generated by the clock distribution module, and since the power supply clock is also based on a global single clock source, the entire system can perform power switch control on the power supply according to the global clock principle. Furthermore, the power supply section is similar to a power amplification module, and spike noise is generated when the switch is turned on. Therefore, based on the same principle, by making the power supply clock from the same clock source as the sampling clock of other components (e.g., an A / D conversion module), the sampling time of the A / D conversion module can be avoided from noise interference from the power supply section, further improving the system's signal-to-noise ratio and interference immunity.

[0053] In each of the above embodiments, one frequency divider among the multiple frequency dividers and its corresponding phase shifter are configured to generate a sensor clock, and another frequency divider among the multiple frequency dividers and its corresponding phase shifter are configured to generate a signal adjustment clock. However, the embodiment is not limited to this, and in other embodiments, as shown in Figure 5, one frequency divider among the multiple frequency dividers and its corresponding phase shifter are configured to generate an intermediate sensing clock, and the phase shift module further includes a secondary phase shifter that performs phase shift processing on the intermediate sensing clock to generate a sensor clock and a signal adjustment clock. The sensor clock and the signal adjustment clock have the same frequency because they are used to form the input signal and reference signal for signal adjustment. The phase shift processing of the secondary phase shifter makes it possible to generate an input signal and a reference signal with the same frequency and orthogonal phase difference. In this way, the secondary phase shifter can be freely positioned when realizing the clock distribution module, for example, by providing the secondary phase shifter in the motor body of a magnetic levitation motor.

[0054] In the above embodiment, the magnetic levitation control unit and the clock distribution module correspond to the control portion of the magnetic levitation motor, and their functions can be realized based on control technologies such as FPGA, MCU, or DSP. Different processors can be selected according to the requirements of the application scenario of the control system. For example, the clock distribution module and the magnetic levitation control unit can be integrated together on a circuit board such as an FPGA, MCU, or DSP. Preferably, the clock distribution module is realized based on an FPGA, the magnetic levitation control unit is realized based on a DSP, the clock signal further includes a system clock, and the DSP's system control is performed based on the system clock. In this way, the clock distribution module generates the system clock, and since the system clock is based on a global single clock source, the entire DSP system performs system control based on the global clock.

[0055] The present invention does not limit the installation method of the analog-to-digital converter (ADC). For example, in general applications, the A / D converter can be integrated into an FPGA, MCU, or DSP, resulting in a simpler and lower-cost overall control system structure. In complex applications with many control channels, the A / D converter can be externally mounted to the FPGA, MCU, or DSP as an independent component, for example, to provide expandability and flexibility in the placement of core processing units.

[0056] Based on a similar inventive concept, the present invention proposes a magnetic levitation motor system based on a global single clock source, which includes a magnetic levitation motor and the magnetic levitation control device described above.

[0057] The present invention does not limit the type of magnetic levitation motor and can be understood as a magnetic levitation rotary drive device that uses magnetic field force to levitate the rotor and has no mechanical contact between the rotor and the stator. Preferably, the magnetic levitation motor may be a magnetic bearing motor, a bearingless motor, a bearingless slice motor, etc.

[0058] A magnetic bearing motor, also known as a magnetic bearing motor, is a combination of a rotational drive motor and / or an axial magnetic bearing and / or a mixed axial and radial magnetic bearing, and / or a motor that is not an integrated unit.

[0059] A bearingless motor is a motor that integrates the rotational function and the levitation function into a single unit. In a bearingless motor, a winding that generates an excitation magnetic field is wound around the winding that generates the rotational drive magnetic field. The interaction of these two magnetic fields disrupts the balance of the original drive magnetic field, generating a radial force acting on the rotor, and by controlling the radial force of the motor, the rotor is levitated.

[0060] The bearingless slice motor is a special type of bearingless motor that retains the advantages of a bearingless motor while having an extremely small ratio of axial length to diameter of the rotor, resulting in a slice-like shape. By eliminating the axial magnetic bearing, bearingless technology enables rotor rotation and radial active levitation, while a magnetic circuit composed of a mechanical structure enables passive levitation in three degrees of freedom other than radial and rotor rotation. It features high cleanliness, no deposition, no particles, no dynamic seals, and superior performance, making it promising for a wide range of applications in ultra-clean drive fields such as biochemistry, medicine, and semiconductor manufacturing.

[0061] Bearingless slice motors can be divided into single-winding and double-winding structures based on their winding structure. The present invention does not limit the winding structure of the bearingless slice motor; it may be a single-winding structure or a double-winding structure. In one embodiment, one coil winding is installed on each stator tooth, and this coil winding is a concentrated winding, constituting a single-winding structure of a magnetic levitation motor, and is used for both rotational control and levitation control. In another embodiment, two coil windings are provided on each stator tooth, and these two coil windings may both be concentrated windings, or one coil winding may be a concentrated winding and the other a distributed winding. The two coil windings provided on the stator teeth are wound in a stacked manner, constituting a double-winding structure of a magnetic levitation motor, with one coil winding used for rotational control and the other coil winding used for levitation control. Single-winding magnetic levitation motors have a performance advantage over double-winding magnetic levitation motors because they can achieve both motor rotor rotation and levitation simultaneously using only one set of coil windings.

[0062] For magnetic levitation motors of different structures, the magnetic levitation control unit of the magnetic levitation control device according to the present invention may have two independent control systems, for example, a motor control device for rotational control of a magnetic bearing motor and a magnetic bearing control device for levitation control of a magnetic bearing motor. Preferably, the magnetic levitation motor according to the present invention is a bearingless slice motor, and the magnetic levitation control unit is a magnetic levitation rotation integrated control unit. The magnetic levitation rotation integrated control unit calculates the rotational current component for rotational control of the bearingless slice motor and the levitation current component for levitation control of the bearingless slice motor based on the rotor displacement data and rotor angle data of the bearingless slice motor, and then performs current synthesis on the rotational current component and the levitation current component to generate a power amplification signal.

[0063] The above examples are merely for illustrative purposes and do not limit the embodiments. Those skilled in the art may make different forms of changes or modifications based on the above description. It is not possible, nor is it necessary, to list all embodiments here. Obvious changes or modifications based thereon also fall within the scope of protection of the present invention.

Claims

1. A magnetic levitation control device based on a global single clock source, comprising a sensor module, a power amplification module, an A / D conversion module, and a magnetic levitation control unit, wherein the clock signal of the magnetic levitation control device is generated based on the global single clock source, and the clock signal includes a sensing clock for detection of the sensor module, a sampling clock for sampling of the A / D conversion module, and a power amplification clock for driving the power amplification module, wherein the sensor module is configured to detect control data for a magnetic levitation motor and output a sensor signal based on the sensing clock, the A / D conversion module is configured to convert the sensor signal into a sampling signal based on the sampling clock, the magnetic levitation control unit is configured to perform data calculation processing on the sampling signal to generate a power amplification signal, and the power amplification module is configured to generate a PWM signal based on the power amplification signal and the power amplification clock, and to excite the electromagnetic coil in the magnetic levitation motor based on the PWM signal. A magnetic levitation control device based on a global single clock source, characterized by the following features.

2. The magnetic levitation control device further includes a clock distribution module that generates the clock signal, which includes the sensing clock, the sampling clock, and the power amplification clock, based on the reference clock of the global single clock source. A magnetic levitation control device based on a global single clock source as described in feature 1.

3. The clock distribution module includes a frequency divider module comprising a plurality of frequency dividers, each of which performs frequency division on a reference clock from the global single clock source to generate a plurality of divided clocks, the clock signal comprising the plurality of divided clocks, and the plurality of divided clocks comprising the sensing clock, the sampling clock, and the power amplification clock. A magnetic levitation control device based on a global single clock source as described in feature 2.

4. The clock distribution module further includes a frequency multiplier that generates a multiplied clock by multiplying a reference clock from the global single clock source, and the plurality of frequency dividers perform frequency division based on the multiplied clock. A magnetic levitation control device based on a global single clock source as described in feature 3.

5. The clock distribution module further includes a plurality of frequency multipliers, one of which is connected to the global single clock source to generate a divided clock, the other dividers correspond one-to-one with the plurality of frequency multipliers, the frequency multipliers perform a multiplication process on a reference clock from the global single clock source to generate a multiplied clock, and the dividers perform a division process based on the multiplied clock generated by the corresponding frequency multiplier. A magnetic levitation control device based on a global single clock source as described in feature 3.

6. The clock distribution module further includes a phase shift module, the phase shift module includes a plurality of phase shifters that correspond one-to-one with the plurality of frequency dividers, the phase shifters adjust the phase of the divided clocks from the corresponding frequency dividers, and the clock signal includes the plurality of divided clocks after phase shift adjustment. A magnetic levitation control device based on a global single clock source according to any one of claims 3 to 5.

7. The magnetic levitation control device further includes a communication port for communication connections to write frequency division and / or phase shift values. A magnetic levitation control device based on a global single clock source as described in feature 6.

8. The sensor module includes a sensor assembly and a signal adjustment module, the sensing clock includes a sensor clock and a signal adjustment clock, the sensor assembly is configured to detect control data for the magnetic levitation motor based on the sensor clock and generate a sensor signal including the control data, and the signal adjustment module is configured to adjust and process the sensor signal including the control data based on the signal adjustment clock and generate an adjusted sensor signal. A magnetic levitation control device based on a global single clock source as described in feature 6.

9. The sensor assembly includes a displacement sensor for detecting rotor displacement data of the magnetic levitation motor, and / or a position angle sensor for detecting rotor angle data of the magnetic levitation motor, and / or a current sensor for detecting current data of the electromagnetic coil of the magnetic levitation motor, and the sensor signals include a rotor displacement signal, and / or a rotor angle signal, and / or a current signal. A magnetic levitation control device based on a global single clock source as described in feature 8.

10. One of the plurality of frequency dividers and its corresponding phase shifter are configured to generate the sensor clock, another of the plurality of frequency dividers and its corresponding phase shifter are configured to generate the signal adjustment clock, or one of the plurality of frequency dividers and its corresponding phase shifter are configured to generate an intermediate sensing clock, and the phase shift module further includes a secondary phase shifter that performs phase shift processing on the intermediate sensing clock to generate the sensor clock and the signal adjustment clock. A magnetic levitation control device based on a global single clock source as described in feature 8.

11. The magnetic levitation control device further includes a power supply, the clock signal further includes a power supply clock, and the power switch of the power supply is based on the power supply clock. A magnetic levitation control device based on a global single clock source as described in feature 2.

12. The magnetic levitation control unit is an integrated magnetic levitation and rotation control unit. Based on the rotor displacement data and rotor angle data of the magnetic levitation motor, the integrated magnetic levitation and rotation control unit calculates the rotational current component for rotational control of the magnetic levitation motor and the levitation current component for levitation control of the magnetic levitation motor, and then performs current synthesis on the rotational current component and the levitation current component to generate a current command signal. A magnetic levitation control device based on a global single clock source as described in feature 1.

13. The power amplification module includes a PWM generator and an output stage, the PWM generator generating a PWM signal for performing PWM control on the output stage based on the power amplification clock and the power amplification signal. A magnetic levitation control device based on a global single clock source as described in feature 1.

14. The PWM generator is integrated into the magnetic levitation control unit. A magnetic levitation control device based on a global single clock source as described in feature 13.

15. The clock distribution module is implemented based on an FPGA, the magnetic levitation control unit is implemented based on a DSP, the clock signal further includes a system clock, and the system control of the DSP is performed based on the system clock. A magnetic levitation control device based on a global single clock source as described in feature 2.

16. Both the clock distribution module and the magnetic levitation control unit are implemented based on an FPGA, MCU, or DSP. A magnetic levitation control device based on a global single clock source as described in feature 2.

17. The A / D conversion module is either built into the FPGA, MCU, or DSP, or it is externally connected to the FPGA, MCU, or DSP. A magnetic levitation control device based on a global single clock source as described in feature 16.

18. Includes a magnetic levitation motor and a magnetic levitation control device according to any one of claims 1 to 17. A magnetic levitation motor system based on a global single clock source, characterized by the following features.

19. The magnetic levitation motor is a magnetic bearing motor, a bearingless motor, or a bearingless slice motor. A magnetic levitation motor system based on a global single clock source as described in feature 18.

Images