阅读说明：本技术 一种低损耗的无轴承电机正弦脉宽调制优化控制方法 (Low-loss optimization control method for sine pulse width modulation of bearingless motor ) 是由 鲍旭聪 王贝易 于 2021-09-16 设计创作，主要内容包括：本发明公开了一种低损耗的无轴承电机正弦脉宽调制优化控制方法,涉及无轴承电机领域,该方法中每个控制器基于无轴承电机的运行参数处理得到当前时刻无轴承电机在αβ坐标系下的指令电压信号,结合历史参考周期的指令电压信号的布尔值确定指令电压零点信号的布尔值,结合优化后的正弦脉宽调制算法得到相应的开关控制信号,使得电机相绕组两端其中一端桥臂工作于运行基频级的开关频率,另一端桥臂工作于系统频率级的开关频率,降低了功率变换器整体的开关频率,从而降低损耗。(The invention discloses a low-loss bearingless motor sine pulse width modulation optimization control method, which relates to the field of bearingless motors.)

1. The low-loss bearingless motor sine pulse width modulation optimization control method is characterized in that the method is applied to a bearingless motor control system, the bearingless motor control system comprises a bearingless motor, a plurality of H-bridge inverters, a suspension controller and a torque controller, each H-bridge inverter is respectively connected with a direct-current power supply, the middle point of a first bridge arm is connected with the positive end of one phase winding of the bearingless motor, the middle point of a second bridge arm is connected with the negative end of the same phase winding, and the phase winding of the bearingless motor comprises the suspension winding and the torque winding; the suspension controller is connected with and controls the working state of an H-bridge inverter connected to the suspension winding, and the torque controller is connected with and controls the working state of the H-bridge inverter connected to the torque winding;

for any of the levitation controller and the torque controller, the method performed comprises:

assigning an initial value to the command voltage zero signal as a preset initial Boolean value;

processing based on the operating parameters of the bearingless motor to obtain an instruction voltage signal of the bearingless motor under an alpha beta coordinate system at the current moment;

if the command voltage signal of the current period is greater than 0, the command voltage signal of the historical reference period is less than 0, and the product of the command voltage signal of the current period and the command voltage signal of the historical reference period is less than 0, taking the command voltage zero signal as an opposite Boolean value, otherwise keeping the Boolean value of the command voltage zero signal unchanged;

if the command voltage zero signal is the preset initial Boolean value, a sinusoidal pulse width modulation algorithm is used for obtaining a first switch control signal to act on the corresponding H-bridge inverter, otherwise, a sinusoidal pulse width modulation algorithm is used for obtaining a second switch control signal to act on the corresponding H-bridge inverter, a switch tube on each bridge arm in the H-bridge inverter respectively works at the switching frequency of a system frequency level and a running fundamental frequency level under the two switch control signals, and the switching frequency of the running fundamental frequency level is lower than the system frequency level.

2. The method according to claim 1, characterized in that under the action of a first switching control signal, the switching tubes of a first leg connected to the positive ends of the phase windings of the bearingless motor operate at a switching frequency of a fundamental operating frequency level, and the switching tubes of a second leg connected to the negative ends of the phase windings of the bearingless motor operate at a switching frequency of a system frequency level; under the action of a second switch control signal, a switch tube on a first bridge arm connected with the positive end of the phase winding of the bearingless motor works at the switching frequency of a system frequency level, and a switch tube on a second bridge arm connected with the negative end of the phase winding of the bearingless motor works at the switching frequency of an operation fundamental frequency level.

3. The method of claim 1, wherein the command voltage signal of the historical reference cycle is a command voltage signal of p previous cycles of the current cycle, and p ≧ 1.

4. The method of claim 1, wherein the command voltage signal is a boolean variable and the preset initial boolean value of the command voltage zero signal is 0 or 1.

5. The method according to any one of claims 1 to 4, wherein the operation parameters of the bearingless motor comprise a real-time levitation current, a real-time torque current, a real-time rotor angle and a real-time displacement signal, the levitation controller processes the real-time levitation current, the real-time rotor angle and the real-time displacement signal to obtain a command voltage signal corresponding to the H-bridge inverter connected to the levitation winding, and the torque controller processes the real-time torque current, the real-time rotor angle and the real-time displacement signal to obtain a command voltage signal corresponding to the H-bridge inverter connected to the torque winding.

6. The method of claim 5, wherein the real-time levitation current is sampled by a current sensor mounted on the levitation winding, the real-time torque current is sampled by a current sensor mounted on the torque winding, the real-time rotor rotation angle is calculated from an angle value sampled by a Hall sensor, and the real-time displacement signal is sampled by an eddy current sensor.

Technical Field

The invention relates to the field of bearingless motors, in particular to a low-loss bearingless motor sine pulse width modulation optimization control method.

Background

The bearingless motor has the advantages of no abrasion, no need of lubricant, low operation noise and high axial utilization rate, and is widely applied to the fields of wafer cleaning in semiconductor manufacturing, transportation in the biopharmaceutical industry and artificial heart blood pumps.

In order to ensure the running precision of the bearingless motor, a system control strategy usually adopts a sine pulse width modulation control strategy or a space vector pulse width modulation control strategy, and the sine pulse width modulation control strategy or the space vector pulse width modulation control strategy is more widely applied due to simple realization. However, the problem of large system loss exists in the traditional bearingless motor sine pulse width modulation optimization control strategy under the condition of higher system control frequency.

Disclosure of Invention

The invention provides a low-loss optimization control method for sinusoidal pulse width modulation of a bearingless motor aiming at the problems and the technical requirements, and the technical scheme of the invention is as follows:

a low-loss bearingless motor sine pulse width modulation optimization control method is applied to a bearingless motor control system, the bearingless motor control system comprises a bearingless motor, a plurality of H-bridge inverters, a suspension controller and a torque controller, each H-bridge inverter is respectively connected with a direct-current power supply, the middle point of a first bridge arm is connected with the positive end of one phase winding of the bearingless motor, the middle point of a second bridge arm is connected with the negative end of the same phase winding, and the phase winding of the bearingless motor comprises the suspension winding and the torque winding; the suspension controller is connected with and controls the working state of the H-bridge inverter connected to the suspension winding, and the torque controller is connected with and controls the working state of the H-bridge inverter connected to the torque winding;

for any of the levitation controller and the torque controller, a method is performed comprising:

assigning an initial value to the command voltage zero signal as a preset initial Boolean value;

processing based on the operation parameters of the bearingless motor to obtain an instruction voltage signal of the bearingless motor at the current moment under an alpha beta coordinate system;

if the command voltage signal of the current period is greater than 0, the command voltage signal of the historical reference period is less than 0, and the product of the command voltage signal of the current period and the command voltage signal of the historical reference period is less than 0, taking the command voltage zero signal as an opposite Boolean value, otherwise keeping the Boolean value of the command voltage zero signal unchanged;

if the command voltage zero signal is a preset initial Boolean value, a sinusoidal pulse width modulation algorithm is used for obtaining a first switch control signal to act on the corresponding H-bridge inverter, otherwise a sinusoidal pulse width modulation algorithm is used for obtaining a second switch control signal to act on the corresponding H-bridge inverter, a switch tube on each bridge arm in the H-bridge inverter respectively works at the switching frequency of a system frequency level and a running fundamental frequency level under two switch control signals, and the switching frequency of the running fundamental frequency level is lower than the system frequency level.

Under the action of a first switch control signal, a switch tube on a first bridge arm connected with the positive end of a phase winding of the bearingless motor works at the switching frequency of a running fundamental frequency level, and a switch tube on a second bridge arm connected with the negative end of the phase winding of the bearingless motor works at the switching frequency of a system frequency level; under the action of a second switch control signal, a switch tube on a first bridge arm connected with the positive end of the phase winding of the bearingless motor works at the switching frequency of a system frequency level, and a switch tube on a second bridge arm connected with the negative end of the phase winding of the bearingless motor works at the switching frequency of an operation fundamental frequency level.

The further technical scheme is that the instruction voltage signal of the historical reference period is the instruction voltage signal of the previous p periods of the current period, and p is more than or equal to 1.

The further technical scheme is that the command voltage signal is a Boolean variable, and the preset initial Boolean value of the command voltage zero signal is 0 or 1.

The further technical scheme is that the operation parameters of the bearingless motor comprise real-time suspension current, real-time torque current, real-time rotor corner and real-time displacement signals, the suspension controller processes the real-time suspension current, the real-time rotor corner and the real-time displacement signals to obtain command voltage signals corresponding to the H-bridge inverter connected to the suspension winding, and the torque controller processes the real-time torque current, the real-time rotor corner and the real-time displacement signals to obtain command voltage signals corresponding to the H-bridge inverter connected to the torque winding.

The further technical scheme is that the real-time suspension current is obtained by sampling through a current sensor arranged on a suspension winding, the real-time torque current is obtained by sampling through a current sensor arranged on a torque winding, the real-time rotor rotation angle is obtained by calculating an angle value sampled by a Hall sensor, and the real-time displacement signal is obtained by sampling through an eddy current sensor.

The beneficial technical effects of the invention are as follows:

the application discloses a low-loss bearingless motor sine pulse width modulation optimization control method which achieves that a bridge arm at one end of two ends of a motor phase winding works at a switching frequency of a running base frequency level and a bridge arm at the other end works at a switching frequency of a system frequency level by reasonably distributing the turn-on time of a switching tube in an H-bridge inverter, reduces the overall switching frequency of a power converter and accordingly reduces loss. On the basis, aiming at the problem that service lives of bridge arms at two ends of a motor phase winding are different due to different switching frequencies, a two-end symmetrical working scheme is provided, the overall service life of the system is further prolonged, and the bearingless motor control system under the control strategy is simple in structure, low in loss, high in efficiency and long in service life.

Drawings

FIG. 1 is a schematic diagram of the control logic of a bearingless motor control system to which the method disclosed herein is applied.

Fig. 2 is a schematic diagram of control waveforms for controlling an H-bridge inverter connected to one phase winding in one example using the method disclosed herein.

Detailed Description

The following further describes the embodiments of the present invention with reference to the drawings.

The application discloses a low-loss bearingless motor sine pulse width modulation optimization control method, which is applied to a bearingless motor control system, please refer to fig. 1, wherein the bearingless motor control system comprises a bearingless motor, a plurality of H-bridge inverters, a suspension controller and a torque controller, each H-bridge inverter is respectively connected with a direct-current power supply, the middle point of a first bridge arm is connected with the positive end of one phase winding of the bearingless motor, and the middle point of a second bridge arm is connected with the negative end of the same phase winding. The phase windings of the bearingless motor comprise a levitation winding and a torque winding, so that two H-bridge inverters are required for a single-phase bearingless motor and four H-bridge inverters are required for a two-phase bearingless motor. The suspension controller is connected with and controls the working state of the H-bridge inverter connected to the suspension winding, and the torque controller is connected with and controls the working state of the H-bridge inverter connected to the torque winding.

For any of the levitation controller and the torque controller, the method performed comprises the steps of:

(1) and giving an initial value to the command voltage zero signal as a preset initial Boolean value. The preset initial boolean value of the command voltage zero signal is 0(True) or 1(False), which does not affect the following method of the present application.

(2) And processing based on the operation parameters of the bearingless motor to obtain the command voltage signal of the bearingless motor at the current moment in an alpha beta coordinate system, wherein the obtained command voltage signal is a Boolean variable.

Specifically, the operation parameters of the bearingless motor comprise real-time suspension current, real-time torque current, real-time rotor rotation angle and real-time displacement signals. The real-time suspension current is obtained by sampling through a current sensor arranged on a suspension winding, the real-time torque current is obtained by sampling through a current sensor arranged on a torque winding, the real-time rotor rotation angle is obtained by calculating an angle value sampled by a Hall sensor, and the real-time displacement signal is obtained by sampling through an eddy current sensor.

And the suspension controller processes the signals based on the real-time suspension current, the real-time rotor rotation angle and the real-time displacement to obtain a command voltage signal corresponding to the H-bridge inverter connected to the suspension winding. Fig. 1 shows a schematic logic control diagram of a levitation controller processing a command voltage signal, specifically: comparator to real-time displacement signal D_xyAnd a displacement set value D_xyrefObtaining the radial reference force F of the rotor through the displacement regulator after comparison_xyrefObtaining a suspension reference current i under dq coordinate system through a decoupling model_Ldqref. Real-time levitation current i_LabIncorporating real-time rotor angle θ_rCoordinate transformation is carried out to obtain the actual suspension current i under the dq coordinate system_Ldq. Comparator pair floating actual current i_LdqAnd a floating reference current i_LdqrefObtaining the suspension command voltage u under dq coordinate system through the current regulator after comparison_LdqCombined with real-time rotor angle theta_rObtaining a command voltage signal under an alpha beta coordinate system at the current moment through coordinate inverse transformationAndthe specific operations such as decoupling model, coordinate transformation, inverse coordinate transformation, etc. are conventional, and are not described in detail herein.

And the torque controller processes the signals based on the real-time torque current, the real-time rotor rotation angle and the real-time displacement to obtain a command voltage signal corresponding to the H-bridge inverter connected to the torque winding. Fig. 1 shows a schematic logic control diagram of a torque controller processing a command voltage signal, specifically: for real-time rotor rotation angle theta_rCarrying out differential operation to obtain the motor rotation speed omega, and comparing the motor rotation speed omega with a rotation speed set value omega by a comparator_refAfter comparison, a torque reference current i under the dq coordinate system is obtained through a rotating speed regulator_Tdqref. Real time torque current i_TabIncorporating real-time rotor angle θ_rCarrying out coordinate transformation to obtain the actual torque current i in the dq coordinate system_Tdq. Comparator versus torque actual current i_TdqAnd a torque reference current i_TdqrefObtaining a torque command voltage u in dq coordinate system through the current regulator after comparison_TdqCombined with real-time rotor angle theta_rObtaining a command voltage signal u under an alpha beta coordinate system at the current moment through coordinate inverse transformation_α(k) And u_β(k) In that respect The specific operations such as coordinate transformation and coordinate inverse transformation are conventional, and are not described in detail herein.

(3) And if the command voltage signal of the current period is greater than 0, the command voltage signal of the historical reference period is less than 0, and the product of the command voltage signal of the current period and the command voltage signal of the historical reference period is less than 0, taking the command voltage zero signal as an opposite Boolean value, otherwise, keeping the Boolean value of the command voltage zero signal unchanged.

The command voltage signal of the historical reference period is currentThe command voltage signal of the first p periods of the period, p is more than or equal to 1. It is more common to take p to 1 so that the command voltage signal of the historical reference cycle is the command voltage signal of the previous cycle, for example, the command voltage signal of the current cycle is u_α(k) The command voltage signal of the historical reference period is u_α(k-1). However, in order to prevent the ripple effect, p > 1 can be taken, and the command voltage signal of the historical reference period adopts the command voltage signal of the first two periods and even a longer time delay.

(4) If the command voltage zero signal is a preset initial Boolean value, a sinusoidal pulse width modulation algorithm is used for obtaining a first switch control signal to act on the corresponding H-bridge inverter, otherwise, a sinusoidal pulse width modulation algorithm is used for obtaining a second switch control signal to act on the corresponding H-bridge inverter, and the switch tube on each bridge arm in the H-bridge inverter respectively works at the switching frequency of a system frequency level and the switching frequency of an operation fundamental frequency level under the two switch control signals. Wherein, the system frequency level represents the conventional switching frequency, and the switching frequency of the operation basic frequency level is lower than the system frequency level.

Specifically, under the action of the first switch control signal, the switch tube on the first bridge arm connected to the positive end of the phase winding of the bearingless motor works at the switching frequency of the operating fundamental frequency level, and the switch tube on the second bridge arm connected to the negative end of the phase winding of the bearingless motor works at the switching frequency of the system frequency level. Under the action of a second switch control signal, a switch tube on a first bridge arm connected with the positive end of the phase winding of the bearingless motor works at the switching frequency of a system frequency level, and a switch tube on a second bridge arm connected with the negative end of the phase winding of the bearingless motor works at the switching frequency of an operation fundamental frequency level.

The method realizes that the bridge arm at one end of two ends of the motor phase winding works at the switching frequency of the operation base frequency level and the bridge arm at the other end works at the switching frequency of the system frequency level by reasonably distributing the turn-on time of the switching tube, reduces the overall switching frequency of the power converter and further reduces the loss. On the basis, aiming at the problem that service lives of bridge arms at two ends of a motor phase winding are different due to different switching frequencies, a two-end symmetrical working scheme is provided, the overall service life of the system is further prolonged, and the bearingless motor control system under the control strategy is simple in structure, low in loss, high in efficiency and long in service life.

Referring to fig. 2, a schematic diagram of a control waveform of an H-bridge inverter connected to a phase winding is shown, and a command voltage signal u in an α β coordinate system is obtained by a torque controller_α(k) For example, assuming that the preset initial boolean value of the command voltage zero signal is 0, during operation:

when the command voltage zero signal N is equal to 0, the control signal g with the switching frequency of the operation basic frequency stage is used₁Control switch tube S₁According to the formula g₁Control signals g with the same switching frequency and opposite phases₂Control switch tube S₂According to a control signal g having a switching frequency of the system frequency level₃Control switch tube S₃According to the formula g₃Control signals g with the same switching frequency and opposite phases₄Control switch tube S₄. So that the switching tube S on the first bridge arm connecting the positive ends of the phase windings of the bearingless motor₁And S₂A switching tube S on the second bridge arm operating at the switching frequency of the fundamental operating frequency stage and connected to the negative end of the phase winding of the bearingless motor₃And S₄Operating at the switching frequency of the system frequency stage.

When the command voltage zero signal N is 1, the control signal g having the switching frequency of the system frequency level is used₃Control switch tube S₁According to the formula g₃Control signals g with the same switching frequency and opposite phases₄Control switch tube S₂According to a control signal g having a switching frequency for operating the fundamental frequency stage₁Control switch tube S₃According to the formula g₁Control signals g with the same switching frequency and opposite phases₂Control switch tube S₄. So that the switching tube S on the first bridge arm connecting the positive ends of the phase windings of the bearingless motor₁And S₂A switching tube S connected to the second bridge arm of the negative end of the phase winding of the bearingless motor and operating at the switching frequency of the system frequency level₃And S₄Operating at the switching frequency of the operating base frequency stage.

What has been described above is only a preferred embodiment of the present application, and the present invention is not limited to the above embodiment. It is to be understood that other modifications and variations directly derivable or suggested by those skilled in the art without departing from the spirit and concept of the present invention are to be considered as included within the scope of the present invention.