阅读说明：本技术 一种磁悬浮开关磁阻电机的共励磁控制方法 (Co-excitation control method of magnetic suspension switched reluctance motor ) 是由 刘泽远 梁智 陈梅 于 2020-12-01 设计创作，主要内容包括：本发明公开了一种磁悬浮开关磁阻电机的共励磁控制方法,磁悬浮开关磁阻电机包括E型定子主动磁轴承和传统的12/8开关磁阻电机,其中12/8开关磁阻电机产生转矩,主动磁轴承产生悬浮力,磁轴承的绕组包括产生偏置磁通的偏置绕组和产生悬浮力的悬浮绕组,偏置绕组与电枢绕组串联在同一变换器上产生偏置电流；磁轴承悬浮控制,先对位移误差进行PID调节得到悬浮力以及共励磁变换器采样得到的偏置电流一起通过有限元径向磁轴承电流查表得到给定径向悬浮电流,并通过对悬浮误差电流极性判断来控制H桥功率变换器前桥臂开关管一个PWM周期内的导通信号以及通过公式计算后桥臂开关管占空比,实现三电平控制,进而控制径向悬浮力,减少悬浮输出电流纹波。(The invention discloses a co-excitation control method of a magnetic suspension switched reluctance motor, wherein the magnetic suspension switched reluctance motor comprises an E-shaped stator active magnetic bearing and a traditional 12/8 switched reluctance motor, wherein the 12/8 switched reluctance motor generates torque, the active magnetic bearing generates suspension force, windings of the magnetic bearing comprise a bias winding generating bias magnetic flux and a suspension winding generating suspension force, and the bias winding and an armature winding are connected in series on the same converter to generate bias current; and (2) magnetic bearing suspension control, wherein PID (proportion integration differentiation) adjustment is performed on displacement errors to obtain suspension force, bias current obtained by sampling of a co-excitation converter is checked through finite element radial magnetic bearing current to obtain given radial suspension current, the polarity of the suspension error current is judged to control a conducting signal in one PWM (pulse-width modulation) period of a front bridge arm switching tube of the H-bridge power converter and the duty ratio of a rear bridge arm switching tube is calculated through a formula, so that three-level control is realized, the radial suspension force is further controlled, and suspension output current ripples are reduced.)

1. A magnetic levitation switch reluctance machine co-excitation control method, the magnetic levitation switch reluctance machine includes E-type stator active magnetic bearing and 12/8 switch reluctance machine, each stator pole of the said 12/8 switch reluctance machine has an armature winding, every four armature winding coils separated by 90 degrees are connected in series, form the three-phase winding separately, in the active magnetic bearing of E-type stator, there are four E-type stators, each E-type stator includes a wide pole and two narrow poles, each wide magnetic pole has a bias coil, each narrow magnetic pole has a suspension winding; the winding of the magnetic bearing comprises a bias winding and a suspension winding, wherein the bias winding generates bias magnetic flux required by suspension, the suspension winding generates suspension force, the winding of the switched reluctance motor comprises an A-phase armature winding, a B-phase armature winding and a C-phase armature winding, three phases are shared and are used for generating torque, and the bias winding and the armature winding are connected in series on a co-excitation power converter to generate bias current, and the magnetic bearing is characterized in that: step A, acquiring a displacement signal of a magnetic bearing rotor to obtain given suspension force in the X-axis and Y-axis directions;

b, obtaining given radial suspension current values in the X-axis direction and the Y-axis directionAndgiven suspension force in the X-axis direction and the Y-axis direction is obtained from the previous step, and the bias current i at the bias winding side of the magnetic suspension switch reluctance motor co-excitation power converter is detected in real time_biasObtaining the given radial suspension current value in the X-axis direction by a finite element radial magnetic bearing current table look-up modeAnd given radial levitation current value in the Y-axis direction

Step C, acquiring a control signal of a front bridge arm switching tube and a duty ratio of a rear bridge arm switching tube of the H-bridge power converter, rapidly reducing current ripples along with given radial current, and controlling a magnetic bearing;

step D, obtaining a phase winding current reference value i of the switched reluctance motor during the phase torque excitation^*And opening angle theta_on；

And E, adjusting the torque during the phase torque excitation.

2. The co-excitation control method of a magnetic suspension switched reluctance motor according to claim 1, characterized in that: the step A specifically comprises the following steps: step A-1, detecting the displacement X and Y of the rotor by the X-axis and Y-axis position sensors, and setting the displacement X and Y and the displacement X in the given X-axis direction^*And given Y-axis direction displacement Y^*Comparing to obtain displacement error values delta y and delta x;

step A-2, carrying out PID adjustment on the obtained displacement error value delta X in the X-axis direction and the obtained displacement error value delta Y in the Y-axis direction to obtain the given suspension force in the X-axis directionAnd given levitation force in the Y-axis direction

3. The co-excitation control method of a magnetic suspension switched reluctance motor according to claim 2, characterized in that: the step C specifically comprises the following steps: c-1, detecting the current i of the suspension winding in two directions by the current sensors in the X-axis direction and the Y-axis direction_x、i_yAnd collecting the current value i_x、i_yGiven radial suspension current value obtained by finite element table lookupComparing to obtain an error value delta i_xAnd Δ i_y；

C-2, controlling the suspension force in the X-axis direction and the Y-axis direction by adopting power circuits of two H-bridge structures, wherein the H-bridge structures are that switching tubes V1 and V2/(V5 and V6) are connected in series to form a left bridge arm, the switching tube V1/(V5) is an upper bridge arm, and the switching tube V2/(V6) is a lower bridge arm; the switching tubes V3 and V4/(V7 and V8) are connected in series to form a right arm, wherein the switching tube V3/(V7) is an upper arm, and the switching tube V4/(V8) is a lower arm; the suspension winding is connected in series between the left bridge arm and the right bridge arm;

in the X-axis direction, the radial suspension error current delta i is temporarily collected at the rising edge of the PWM waveform_xJudging the radial suspension error current delta i_xAnd maintaining one PWM period; when the error signal value Δ i_xIf the polarity is positive, the upper switch tube V1 of the front bridge arm of the H-bridge power converter is kept on in the time period, the lower switch tube V2 is switched off, and the upper switch tube and the lower switch tube are in complementary conduction;

when the error signal value Δ i_xIf the polarity is negative, the upper switch tube V1 on the front bridge arm of the H-bridge power converter is kept off in the time period, the lower switch tube V2 is switched on, and the upper switch tube and the lower switch tube are in complementary conduction;

in the Y-axis direction, the radial suspension error current delta i is temporarily collected at the rising edge of the PWM waveform_yJudging the radial suspension error current delta i_yAnd maintaining one PWM period; when the error signal value Δ i_yIf the polarity is positive, the upper switch tube V5 of the front bridge arm of the H-bridge power converter is kept on in the time period, the lower switch tube V6 is switched off, and the upper switch tube and the lower switch tube are in complementary conduction;

when the error signal value Δ i_yIf the polarity is negative, the upper switch tube V5 on the front bridge arm of the H-bridge power converter is kept off in the time period, the lower switch tube V6 is switched on, and the upper switch tube and the lower switch tube are in complementary conduction;

step C-3, acquiring error signal values of radial suspension current in real time in a PWM time period in the X-axis direction through a formulaCalculating the duty ratio of a switching tube V4 under the rear bridge arm of the H-bridge power converter, and calculating the duty ratio when the error signal value delta i_xThe polarity is positive, the duty ratio of a lower switch tube V4 of a rear bridge arm of the H-bridge power converter is calculated to be 1 through a formula, a lower switch tube V4 is fully turned on, an upper switch tube V3 is turned off, and the upper switch tube and the lower switch tube are complementarily turned on; when the error signal value Δ i_xThe polarity is negative, the duty ratio of a lower switch tube V4 of a rear bridge arm of the H-bridge power converter is calculated to be 0 through a formula, the lower switch tube V4 is turned off, and an upper switch tube V3 is turned on;

in a PWM period, the front bridge arm is in a conducting state with a switch V1, the rear bridge arm collects the error signal value of the suspension current in real time to calculate the duty ratio, and when the error signal value delta i is_xThe polarity is positive, the switch tube V4 under the rear bridge arm is switched on, the power supply voltage is the positive charging of the suspension winding and is marked as a plus state, and when the error signal value delta i_xWhen the polarity is negative, the switching tube V4 under the rear bridge arm is turned off, and the suspension winding enters a follow current state and is marked as a '0' state;

in a PWM period, the front bridge arm is in a turn-off state with the switch V1, the rear bridge arm collects the error signal value of the suspension current in real time to calculate the duty ratio, and when the error signal value delta i_xWhen the polarity is negative, the switch tube V4 under the rear bridge arm is turned off, the switch tube V3 on the rear bridge arm is turned on, the power supply voltage is reverse charging of the suspension winding and is recorded as a negative state, and when the error signal value delta i_xWhen the polarity is positive, the rear-axle-arm lower switch tube V4 is switched on, and the suspension winding enters a follow current state, namely a '0' state; the three-level control mode can effectively reduce output current ripples and quickly follow a given current value; the method comprises the following steps that (1) conducting signals of all switching tubes of an H-bridge power converter are controlled to enable the switching tubes to give suspension current along the X-axis direction, and then suspension force in the X-axis direction is controlled;

collecting error signal value of radial suspension current in real time in PWM time period in Y-axis direction according to formulaCalculating the duty ratio of a switching tube V8 under the rear bridge arm of the H-bridge power converter, and calculating the duty ratio when the error signal value delta i_yThe polarity is positive, the duty ratio of a lower switch tube V8 of a rear bridge arm of the H-bridge power converter is calculated to be 1 through a formula, a lower switch tube V8 is fully turned on, an upper switch tube V7 is turned off, and the upper switch tube and the lower switch tube are complementarily turned on; when the error signal value Δ i_yThe polarity is negative, the duty ratio of a lower switch tube V8 of a rear bridge arm of the H-bridge power converter is calculated to be 0 through a formula, the lower switch tube V8 is turned off, and an upper switch tube V7 is turned on;

at one isIn the PWM period, when a switch V5 on the front bridge arm is in a conducting state, the rear bridge arm collects a suspension current error signal value in real time to calculate the duty ratio, and when the error signal value delta i_yThe polarity is positive, the switch tube V8 under the rear bridge arm is switched on, the power supply voltage is the positive charging of the suspension winding and is marked as a plus state, and when the error signal value delta i_yWhen the polarity is negative, the switching tube V8 under the rear bridge arm is turned off, and the suspension winding enters a follow current state and is marked as a '0' state;

in a PWM period, the front bridge arm is in a turn-off state with the switch V5, the rear bridge arm collects the error signal value of the suspension current in real time to calculate the duty ratio, and when the error signal value delta i_yWhen the polarity is negative, the switch tube V8 under the rear bridge arm is turned off, the switch tube V7 on the rear bridge arm is turned on, the power supply voltage is reverse charging of the suspension winding and is recorded as a negative state, and when the error signal value delta i_yWhen the polarity is positive, the rear-axle-arm lower switch tube V8 is switched on, and the suspension winding enters a follow current state, namely a '0' state; the three-level control mode can effectively reduce output current ripples and quickly follow a given current value; and the H-bridge power converter is enabled to give suspension current along the Y-axis direction by controlling the conduction signal of each switching tube, so that the suspension force in the Y-axis direction is controlled.

4. The co-excitation control method of a magnetic suspension switched reluctance motor according to claim 3, characterized in that: the step D specifically comprises the following steps: d-1, calculating to obtain a rotor angular speed omega according to the rotor rotating speed;

d-2, comparing the rotor angular speed omega with a set reference angular speed omega to obtain a rotation speed difference delta omega;

step D-3, when omega is less than or equal to omega₀Time, omega₀The set value of the critical angular speed is determined by the actual working condition of the motor; the reference value i of the phase winding current is obtained through a PI controller by the speed difference delta omega^*(ii) a Angle of closure theta_offIs constant, wherein theta_offThe value is determined by the structural form of the motor;

step D-4, when omega is larger than omega₀Then, the opening angle theta is obtained through the PI controller according to the rotating speed difference delta omega_onThe phase winding current is not controlled at this time.

5. The co-excitation control method of the magnetic suspension switched reluctance motor according to claim 4, characterized in that: the step E specifically comprises the following steps: step E-1, when omega is less than or equal to omega₀Then, the current chopping control method is utilized to enable the actual current i of the phase winding to track the reference value i of the current of the phase winding during the phase torque excitation^*Further adjusting the current i of the phase winding in real time to realize torque adjustment;

step E-2, when omega is larger than omega₀By using an angle position control method, the opening angle theta is dynamically adjusted_onTo achieve an adjustment of the torque.

6. The co-excitation control method of the magnetic suspension switched reluctance motor according to claim 5, characterized in that: in the step B, the magnetic suspension switch reluctance motor co-excitation power converter comprises a power supply u_sThe power supply comprises an electrolytic capacitor C1, six power switching tubes from a first power switching tube S1 to a sixth power switching tube S6, six fly-wheel diodes from a first fly-wheel diode VD1 to a sixth fly-wheel diode VD6, two power diodes from a first power diode VD7 and a second power diode VD8, a seventh fly-wheel diode VD9 and an eighth fly-wheel diode VD 10; wherein the power source u_sThe anode of the first power diode VD7 is connected with the anode of the first power diode VD10 and the cathode of the eighth fly-wheel diode VD 10; the cathode of the first power diode VD7 is connected with the cathode of the seventh freewheeling diode VD 9; the anode of the eighth flywheel diode VD10 is connected with the anode of a second power diode VD 8; the anode of the seventh freewheeling diode VD9 is respectively connected with the cathode of the second power diode VD8 and the input end of the electrolytic capacitor C1; the cathode of the second power diode VD8 is respectively connected with the anode of the seventh freewheeling diode VD9, the input end of the electrolytic capacitor C1, the drain of the first power switch tube S1, the cathode of the first freewheeling diode VD1, the drain of the third power switch tube S3, the cathode of the third freewheeling diode VD3, the drain of the fifth power switch tube VD5 and the cathode of the fifth freewheeling diode VD 5;

power supply u_sThe negative electrode of the first power switch tube is respectively connected with the output end of the electrolytic capacitor C1, the anode of the second fly-wheel diode VD2, the source electrode of the second power switch tube S2 and the fourth electrodeThe anode of the current diode VD4, the source of the fourth power switch tube S4, the anode of the sixth freewheeling diode VD6 and the source of the sixth power switch tube S6;

the source electrode of the first power switch tube S1 is connected with the cathode electrode of the second fly-wheel diode VD 2; the anode of the first freewheeling diode VD1 is connected with the drain of the second power switch tube S2; the source electrode of the third power switch tube S3 is connected with the cathode electrode of the fourth fly-wheel diode VD 4; the anode of the third freewheeling diode VD3 is connected with the drain of the fourth power switch tube S4; the source electrode of the fifth power switch tube S5 is connected with the cathode electrode of the sixth fly-wheel diode VD 6; the anode of the fifth freewheeling diode VD5 is connected with the drain of the sixth power switch tube S6;

a Bias inductance Bias of the magnetic bearing is connected in series between the cathode of the first power diode VD7 and the anode of the second power diode VD 8; an A-phase winding of the switched reluctance motor is connected in series between the source electrode of the first power switch tube S1 and the drain electrode of the second power switch tube; a B-phase winding of the switched reluctance motor is connected in series between the source electrode of the third power switch tube S3 and the drain electrode of the fourth power switch tube S4; the C-phase winding of the switched reluctance motor is connected in series between the source of the fifth power switching tube S5 and the drain of the sixth power switching tube S6.

Technical Field

The invention relates to the technical field of control over magnetic suspension switch reluctance motors of motors, in particular to a co-excitation control method for a magnetic suspension switch reluctance motor.

Background

The magnetic suspension switched reluctance motor is formed by integrating a magnetic bearing system and a switched reluctance motor system, not only has the characteristics of high-speed adaptability of the switched reluctance motor, meeting the harsh working environment and the like, but also has the advantages of no friction, no lubrication and the like of the magnetic bearing, and has unique advantages in the occasions of aerospace, flywheel energy storage, military and the like.

The magnetic bearing in the magnetic suspension switched reluctance motor system can be divided into an electromagnetic bearing and a permanent magnet biased bearing according to a bias magnetic flux providing mode. The permanent magnet bias bearing has high power density, small volume, light weight and wider application; however, because the price of the permanent magnet is high, the high temperature resistance and the corrosion resistance are poor, the application of the permanent magnet in severe occasions such as high temperature and high oil is limited. The electromagnetic bearing adopts an electric excitation mode, so that the application occasion is more flexible.

The magnetic suspension system and the switched reluctance system are mutually independent, the mechanical structure is not compact, and the integration level is low; in addition, the two systems are respectively provided with a separate power converter, so that the cost is high, and the integration level is low. To this end, some researchers have proposed a novel magnetic levitation switched reluctance motor of a series common excitation type in which a magnetic bearing bias winding and a switched reluctance motor winding are connected in series. The motor is characterized in that an armature winding and a bias winding are connected in series and then are connected into a traditional asymmetric half-bridge power converter, the armature winding and the bias winding adopt the same excitation mode, torque is generated in a switched reluctance motor, bias magnetic flux is generated in a magnetic bearing, and then the power converter of the bias winding is eliminated, so that the system integration level is obviously improved.

However, in the above integration method, the number of the bias windings is required to be the same as the number of phases of the switched reluctance motor, so that the number of the windings of the magnetic bearing is correspondingly increased, and the volume of the magnetic bearing is also required to be increased to place more bias windings. Therefore, the scholars further provide a novel magnetic suspension switched reluctance motor, only one bias winding is needed on each stator tooth of the magnetic bearing, all the bias windings are connected in series and connected into a direct current bus of a power converter of the armature winding, and the rapid excitation starting of the motor is ensured while bias current is provided for the bias windings, so that the existing control method is not suitable for a magnetic suspension switched reluctance motor system, the whole system control method is not only suitable for the switched reluctance motor, but also suitable for providing bias current to enable the magnetic bearing to suspend by combining a magnetic bearing switched reluctance motor co-excitation power converter, and can follow a given suspension current value to reduce output suspension current ripples.

Disclosure of Invention

In order to solve the problems, the invention provides the co-excitation control method of the magnetic suspension switched reluctance motor, which can realize the rotation of the switched reluctance motor, the suspension of the magnetic bearing, the reduction of output suspension current ripples, no need of a mathematical model of torque and suspension force in the control process, simple control, reduction of the number of power converters, reduction of the switching times of a switching tube of a suspension power converter and reduction of switching loss.

In order to achieve the purpose, the invention is realized by the following technical scheme:

the invention relates to a co-excitation control method of a magnetic suspension switched reluctance motor, wherein the magnetic suspension switched reluctance motor comprises an E-shaped stator active magnetic bearing and an 12/8 switched reluctance motor, each stator pole of the 12/8 switched reluctance motor is provided with an armature winding, every four armature winding coils which are separated by 90 degrees are connected in series to respectively form a three-phase winding, four E-shaped stators are arranged in the E-shaped stator active magnetic bearing, each E-shaped stator comprises a wide pole and two narrow poles, each wide magnetic pole is provided with a bias coil, and each narrow magnetic pole is provided with a suspension winding; the windings of the magnetic bearing comprise a bias winding and a suspension winding, wherein the bias winding generates bias magnetic flux required by suspension, the suspension winding generates suspension force, and the windings of the switched reluctance motor comprise an A-phase armature winding, a B-phase armature winding and a C-phase armature winding, which are three-phase and used for generating torque; the bias winding and the armature winding are connected in series on the co-excitation power converter to generate bias current, and the power converter is characterized in that: step A, collecting a magnetic bearing rotor displacement signal to obtain given suspension force in the X-axis and Y-axis directions;

b, obtaining given radial suspension current values in the X-axis direction and the Y-axis directionAndgiven suspension force in the X-axis direction and the Y-axis direction is obtained in the previous step, and the bias current i of the bias winding side of the magnetic suspension switch reluctance motor co-excitation power converter is detected in real time_biasObtaining the given radial levitation current value in the X-axis direction by a finite element radial magnetic bearing current table look-up modeAnd given radial levitation current value in the Y-axis directionStep C, acquiring a control signal of a front bridge arm switching tube and a duty ratio of a rear bridge arm switching tube of the H-bridge power converter, rapidly reducing current ripples along with given radial current, and controlling a magnetic bearing;

step D, obtaining a phase winding current reference value of the switched reluctance motor during the phase torque excitationAnd opening angle θ on;

and E, adjusting the torque during the phase torque excitation.

The invention is further improved in that: the step A specifically comprises the following steps: step A-1, detecting the displacement X and Y of the rotor by the X-axis and Y-axis position sensors, and comparing the collected displacement X and Y with the displacement X in the given X-axis direction^*And given Y-axis direction displacement Y^*Comparing to obtain displacement error values delta y and delta x;

step A-2, carrying out PID adjustment on the obtained displacement error value delta X in the X-axis direction and the obtained displacement error value delta Y in the Y-axis direction to obtain the given suspension force in the X-axis directionAnd given levitation force in the Y-axis direction

The invention is further improved in that: the step C specifically comprises the following steps: c-1, detecting the current i of the suspension winding in two directions by the current sensors in the X-axis direction and the Y-axis direction_x、i_yAnd collecting the current value i_x、i_yGiven radial suspension current value obtained by finite element table lookupComparing to obtain an error value delta i_xAnd Δ i_y；

C-2, controlling the suspension force in the X-axis direction and the Y-axis direction by adopting two power circuits with H-bridge structures, wherein the H-bridge structures are that switching tubes V1 and V2/(V5 and V6) are connected in series to form a left bridge arm, the switching tube V1/(V5) is an upper bridge arm, and the switching tube V2/(V6) is a lower bridge arm; the switching tubes V3 and V4/(V7 and V8) are connected in series to form a right arm, wherein the switching tube V3/(V7) is an upper arm, and the switching tube V4/(V8) is a lower arm; the suspension winding is connected in series between the left bridge arm and the right bridge arm;

in the X-axis direction, the radial suspension error current delta i is temporarily collected at the rising edge of the PWM waveform_xJudging the radial suspension error current delta i_xAnd maintaining one PWM period; when the error signal value Δ i_xIf the polarity is positive, the upper switch tube V1 of the front bridge arm of the H-bridge power converter is kept on, the lower switch tube V2 is switched off, and the upper switch tube and the lower switch tube are conducted in a complementary mode in the period of time;

when the error signal value Δ i_xIf the polarity is negative, the upper switch tube V1 on the front bridge arm of the H-bridge power converter is kept off in the time period, the lower switch tube V2 is switched on, and the upper switch tube and the lower switch tube are in complementary conduction;

in the Y-axis direction, the radial suspension error current delta i is temporarily collected at the rising edge of the PWM waveform_yJudging the radial suspension error current delta i_yAnd maintaining one PWM period; when the error signal value Δ i_yIf the polarity is positive, the upper switch tube V5 of the front bridge arm of the H-bridge power converter is kept on, the lower switch tube V6 is switched off, and the upper switch tube and the lower switch tube are conducted in a complementary mode in the period of time;

when the error signal value Δ i_yThe polarity is negative, thenIn the time period, the upper switch tube V5 of the front bridge arm of the H-bridge power converter is kept off, the lower switch tube V6 is switched on, and the upper switch tube and the lower switch tube are conducted in a complementary mode;

and C-3, acquiring the error signal value of the radial suspension current in real time in the PWM time period in the X-axis direction through a formulaCalculating the duty ratio of a switching tube V4 under the rear bridge arm of the H-bridge power converter, and calculating the duty ratio when the error signal value delta i_xThe polarity is positive, the duty ratio of a lower switch tube V4 of a rear bridge arm of the H-bridge power converter is calculated to be 1 through a formula, a lower switch tube V4 is fully turned on, an upper switch tube V3 is turned off, and the upper switch tube and the lower switch tube are in complementary conduction; when the error signal value Δ i_xThe polarity is negative, the duty ratio of a lower switching tube V4 of a rear bridge arm of the H-bridge power converter is calculated to be 0 through a formula, the lower switching tube V4 is turned off, and an upper switching tube V3 is turned on;

in a PWM period, the front bridge arm is in a conducting state with a switch V1, the rear bridge arm collects the error signal value of the suspension current in real time to calculate the duty ratio, and when the error signal value delta i is_xThe polarity is positive, the switch tube V4 under the rear bridge arm is switched on, the power supply voltage is positive charging of the suspension winding and is marked as a plus state, and when the error signal value delta i_xWhen the polarity is negative, the switching tube V4 under the rear bridge arm is turned off, and the suspension winding enters a follow current state and is marked as a '0' state;

in a PWM period, the front bridge arm is in a turn-off state with the switch V1, the rear bridge arm collects the error signal value of the suspension current in real time to calculate the duty ratio, and when the error signal value delta i_xWhen the polarity is negative, the switch tube V4 under the rear bridge arm is turned off, the switch tube V3 on the rear bridge arm is turned on, the power supply voltage is reverse charging of the suspension winding and is recorded as a negative state, and when the error signal value delta i_xWhen the polarity is positive, the rear-axle-arm lower switch tube V4 is switched on, and the suspension winding enters a follow current state, namely a '0' state; the three-level control mode can effectively reduce output current ripples and quickly follow a given current value; the method comprises the following steps that (1) conducting signals of all switching tubes of an H-bridge power converter are controlled to enable the switching tubes to give suspension current along the X-axis direction, and then suspension force in the X-axis direction is controlled;

y-axisDirection, in PWM time period, real-time collecting radial suspension current error signal value through formulaCalculating the duty ratio of a switching tube V8 under the rear bridge arm of the H-bridge power converter, and calculating the duty ratio when the error signal value delta i_yThe polarity is positive, the duty ratio of a lower switch tube V8 of a rear bridge arm of the H-bridge power converter is calculated to be 1 through a formula, a lower switch tube V8 is fully turned on, an upper switch tube V7 is turned off, and the upper switch tube and the lower switch tube are in complementary conduction; when the error signal value Δ i_yThe polarity is negative, the duty ratio of a lower switching tube V8 of a rear bridge arm of the H-bridge power converter is calculated to be 0 through a formula, the lower switching tube V8 is turned off, and an upper switching tube V7 is turned on;

in a PWM period, the front bridge arm is in a conducting state with a switch V5, the rear bridge arm collects the error signal value of the suspension current in real time to calculate the duty ratio, and when the error signal value delta i is_yThe polarity is positive, the switch tube V8 under the rear bridge arm is switched on, the power supply voltage is positive charging of the suspension winding and is marked as a plus state, and when the error signal value delta i_yWhen the polarity is negative, the switching tube V8 under the rear bridge arm is turned off, and the suspension winding enters a follow current state and is marked as a '0' state;

in a PWM period, the front bridge arm is in a turn-off state with the switch V5, the rear bridge arm collects the error signal value of the suspension current in real time to calculate the duty ratio, and when the error signal value delta i_yWhen the polarity is negative, the switch tube V8 under the rear bridge arm is turned off, the switch tube V7 on the rear bridge arm is turned on, the power supply voltage is reverse charging of the suspension winding and is recorded as a negative state, and when the error signal value delta i_yWhen the polarity is positive, the rear-axle-arm lower switch tube V8 is switched on, and the suspension winding enters a follow current state, namely a '0' state; the three-level control mode can effectively reduce output current ripples and quickly follow a given current value; and the H-bridge power converter is enabled to give suspension current along the Y-axis direction by controlling the conduction signal of each switching tube, so that the suspension force in the Y-axis direction is controlled.

The invention is further improved in that: the step D specifically comprises the following steps: d-1, calculating to obtain a rotor angular speed omega according to the rotor rotating speed;

d-2, comparing the rotor angular speed omega with a set reference angular speed omega to obtain a rotation speed difference delta omega;

step D-3, when omega is less than or equal to omega₀Time, omega₀The set value of the critical angular speed is determined by the actual working condition of the motor; the reference value i of the phase winding current is obtained through a PI controller^*(ii) a Angle of closure theta_offIs constant, wherein theta_offThe value is determined by the structural form of the motor;

step D-4, when omega is larger than omega₀Then, the opening angle theta is obtained through the PI controller_onThe phase winding current is not controlled at this time.

The invention is further improved in that: step E-1, when omega is less than or equal to omega₀In time, the current chopping control method is utilized to enable the actual current i of the phase winding to track the current reference value i of the phase winding during phase torque excitation^*Further adjusting the current i of the phase winding in real time to realize torque adjustment;

step E-2, when omega is larger than omega₀By using an angle position control method, the opening angle theta is dynamically adjusted_onTo achieve the regulation of the torque.

The invention is further improved in that: in the step B, the magnetic suspension switch reluctance motor co-excitation power converter comprises a power supply u_sThe power supply comprises an electrolytic capacitor C1, six power switching tubes from a first power switching tube S1 to a sixth power switching tube S6, six fly-wheel diodes from a first fly-wheel diode VD1 to a sixth fly-wheel diode VD6, two power diodes from a first power diode VD7 and a second power diode VD8, a seventh fly-wheel diode VD9 and an eighth fly-wheel diode VD 10; wherein the power source u_sThe anode of the first power diode VD7 is connected with the anode of the first power diode VD10 and the cathode of the eighth fly-wheel diode VD 10; the cathode of the first power diode VD7 is connected with the cathode of the seventh freewheeling diode VD 9; the anode of the eighth flywheel diode VD10 is connected with the anode of the second power diode VD 8; the anode of the seventh freewheeling diode VD9 is respectively connected with the cathode of the second power diode VD8 and the input end of the electrolytic capacitor C1; the cathode of the second power diode VD8 is respectively connected with the anode of the seventh fly-wheel diode VD9, the input end of the electrolytic capacitor C1 and the drain of the first power switch tube S1The diode comprises a pole, a cathode of a first freewheeling diode VD1, a drain electrode of a third power switch tube S3, a cathode of a third freewheeling diode VD3, a drain electrode of a fifth power switch tube VD5 and a cathode of a fifth freewheeling diode VD 5;

power supply u_sThe negative electrode of the second power switch tube is respectively connected with the output end of the electrolytic capacitor C1, the anode of the second fly-wheel diode VD2, the source electrode of the second power switch tube S2, the anode of the fourth fly-wheel diode VD4, the source electrode of the fourth power switch tube S4, the anode of the sixth fly-wheel diode VD6 and the source electrode of the sixth power switch tube S6;

the source electrode of the first power switch tube S1 is connected with the cathode electrode of the second fly-wheel diode VD 2; the anode of the first freewheeling diode VD1 is connected with the drain of the second power switch tube S2; the source electrode of the third power switch tube S3 is connected with the cathode electrode of the fourth fly-wheel diode VD 4; the anode of the third freewheeling diode VD3 is connected with the drain of the fourth power switch tube S4; the source electrode of the fifth power switch tube S5 is connected with the cathode electrode of the sixth fly-wheel diode VD 6; the anode of the fifth freewheeling diode VD5 is connected with the drain of the sixth power switch tube S6;

a Bias inductance Bias of the magnetic bearing is connected in series between the cathode of the first power diode VD7 and the anode of the second power diode VD 8; an A-phase winding of the switched reluctance motor is connected in series between the source electrode of the first power switch tube S1 and the drain electrode of the second power switch tube; a B-phase winding of the switched reluctance motor is connected in series between the source electrode of the third power switch tube S3 and the drain electrode of the fourth power switch tube S4; the C-phase winding of the switched reluctance motor is connected in series between the source of the fifth power switching tube S5 and the drain of the sixth power switching tube S6.

The invention has the beneficial effects that: the invention can obviously improve the utilization rate of the armature winding current of the switched reluctance motor, reduce the cost of a magnetic bearing power system, simplify the difficulty of suspension force control, integrate a magnetic bearing bias winding power converter and a switched reluctance motor three-phase armature winding power converter into a whole, have high integration level, low cost and strong reliability, generate torque by an SRM, adopt the traditional control mode in the control method, adopt a CCC control mode at low speed and adopt an APC control mode at high speed; the suspension control of the magnetic bearing comprises the steps of firstly carrying out PID (proportion integration differentiation) adjustment on displacement errors to obtain suspension force and bias current obtained by sampling of a co-excitation converter, obtaining given radial suspension current through a finite element radial magnetic bearing current table look-up, controlling a conducting signal in one PWM (pulse-width modulation) period of a front bridge arm switching tube of an H-bridge power converter through suspension error current polarity judgment, and calculating the duty ratio of a rear bridge arm switching tube through a formula to realize three-level control, further controlling the radial suspension force and reducing suspension output current ripples.

Drawings

Fig. 1 is a control block diagram of an 12/8 pole magnetic levitation switched reluctance motor system.

Fig. 2 is a schematic diagram of a partially exploded structure of an 12/8 pole magnetic levitation switched reluctance motor.

Fig. 3 is a schematic diagram of the levitation winding and the bias winding.

Fig. 4 is a cross-sectional view and winding schematic of an active magnetic bearing.

Fig. 5 is a topology structure diagram of a co-excitation power converter of a magnetic levitation switched reluctance motor.

Fig. 6 is a working state diagram a of the H-bridge power converter in the three-level control mode.

Fig. 7 is a working state diagram b of the H-bridge power converter in the three-level control mode.

Fig. 8 is a working state diagram c of the H-bridge power converter in the three-level control mode.

Fig. 9 is a diagram d of the operation state of the H-bridge power converter in the three-level control mode.

Fig. 10 shows output current waveforms under different control modes for a given current, where 9 is a given floating current signal, 10 is an output floating current signal for providing an improved ripple control method, and 11 is an output floating current signal after hysteresis control.

Wherein: 12/8 switched reluctance motor, 2E-type stator active magnetic bearing, 3 armature winding, 4 suspension winding, 5 bias winding, i_x±Is the X-axis direction levitation winding current, where the positive sign indicates inflow and the negative sign indicates outflow, i_y±Is the Y-axis direction levitation winding current i_bias±Is the bias winding current i_a±Is the A-phase armature winding current, u_sIs a DC power supply, C1 is electricityThe capacitors are de-capacitors, VD 1-VD 6 and VD 9-VD 10 are respectively first to eighth freewheeling diodes, VD 7-VD 8 are respectively first power diodes and second power diodes, S1-S6 are respectively first to sixth power switching tubes, A, B, C are respectively C-phase windings of B-phase windings and B-phase windings of A-phase windings of the motor, the Bias windings are arranged in a mode of being biased, and y is equal to Y-phase windings^*For a given amount of eccentric displacement of the Y-axis rotor, x^*For a given X-axis direction rotor eccentric displacement, X is the rotor eccentric displacement of the magnetic bearing detected by the X-axis direction position sensor, Y is the rotor eccentric displacement of the magnetic bearing detected by the Y-axis direction displacement sensor, Deltay is the Y-axis direction magnetic bearing rotor displacement error value, Deltax is the X-axis direction magnetic bearing rotor displacement error value, F_yIs a suspension force in the Y-axis direction, F_xIs X-axis buoyancy, i_biasIn order to bias the winding current,given the levitation force current for the Y-axis direction,given levitation current, i, for the X-axis direction_xIs the actual levitation force current of X axis, i_yIs the actual levitation force current in the Y-axis direction, Δ i_xFor X-axis direction levitation current error value, Δ i_yFor the Y-axis direction suspension current error value, V1-V4 are H bridge power converter switch tubes, omega^*For a given rotor angular velocity, ω is the actual angular velocity, ω₀Is a critical angular velocity set value, Δ ω is an angular velocity error value, i^*Is the phase winding current reference value, i is the actual phase winding current, θ_offTo the off angle, θ_onTo open an angle, i_a、i_b、i_cRespectively, a phase B phase and a phase C phase winding current, i_x、i_yAre respectively X-axis and Y-axis suspension currents u_dcFor a DC power supply of an H-bridge converter, L_xThe winding inductance is suspended in the X-axis direction.

Detailed Description

The technical schemes of the system control method of the magnetic suspension switched reluctance motor and the control method for reducing the current ripple of the output suspension winding are explained in detail below with reference to the attached drawings;

as shown in fig. 1-10, the present invention is a co-excitation control method of a magnetic suspension switched reluctance motor, the magnetic suspension switched reluctance motor includes an E-type stator active magnetic bearing 2 and an 12/8 switched reluctance motor 1, each stator pole of the 12/8 switched reluctance motor 1 has an armature winding 3, every four armature windings 3 spaced by 90 ° are connected in series to form three-phase windings, respectively, in the E-type stator active magnetic bearing 2, there are four E-type stators, each E-type stator includes a wide pole and two narrow poles, each wide magnetic pole has a bias coil, and each narrow magnetic pole has a suspension winding 4; the windings of the magnetic bearing comprise a bias winding 5 and a suspension winding 4, wherein the bias winding 5 generates bias magnetic flux required by suspension, the suspension winding 4 generates suspension force, and the windings of the switched reluctance motor comprise an A-phase armature winding, a B-phase armature winding and a C-phase armature winding which are three-phase and used for generating torque; the power converter is suitable for the bias winding and the three-phase armature winding, the bias winding and the armature winding are connected in series on the same co-excitation power converter to generate bias current, the SRM still adopts the traditional control mode, the CCC control mode is adopted at low speed, and the APC control mode is adopted at high speed; the magnetic bearing suspension control comprises the steps of firstly carrying out PID adjustment on displacement errors to obtain suspension force and bias current obtained by sampling of a co-excitation converter, obtaining given radial suspension current through a finite element radial magnetic bearing current table look-up table, controlling a conducting signal in one PWM period of a front bridge arm switching tube of an H bridge power converter through suspension error current polarity judgment and calculating the duty ratio of a rear bridge arm switching tube through a formula to realize three-level control, and further controlling the radial suspension force, wherein the steps are as follows: step A, acquiring a displacement signal of a magnetic bearing rotor to obtain given suspension force in the X-axis and Y-axis directions; step A-1, detecting the displacement X and Y of the rotor by the X-axis and Y-axis position sensors, and setting the displacement X and Y and the displacement X in the given X-axis direction^*And given Y-axis direction displacement Y^*Comparing to obtain displacement error values delta y and delta x;

step A-2, obtaining displacement error value delta X in X-axis direction and displacement error value in Y-axis directionThe delta y is subjected to PID adjustment to obtain the given suspension force in the X-axis directionAnd given levitation force in the Y-axis directionB, obtaining given radial suspension current values in the X-axis direction and the Y-axis directionAndgiven suspension force in the X-axis direction and the Y-axis direction is obtained in the previous step, and the bias current i of the bias winding side of the magnetic suspension switch reluctance motor co-excitation power converter is detected in real time_biasObtaining the given radial levitation current value in the X-axis direction by a finite element radial magnetic bearing current table look-up modeAnd given radial levitation current value in the Y-axis directionStep C, acquiring a control signal of a front bridge arm switching tube and a duty ratio of a rear bridge arm switching tube of the H-bridge power converter, rapidly reducing current ripples along with given radial current, and controlling a magnetic bearing;

c-1, detecting the current i of the suspension winding in two directions by the current sensors in the X-axis direction and the Y-axis direction_x、i_yAnd collecting the current value i_x、i_yGiven radial suspension current value obtained by finite element table lookupComparing to obtain error difference value delta i_xAnd Δ i_y；

C-2, controlling the suspension force in the X-axis direction and the Y-axis direction by adopting two power circuits with H-bridge structures, wherein the H-bridge structure in the X-axis direction is a left bridge arm formed by serially connecting switching tubes V1 and V2, the switching tube V1 is an upper bridge arm, the switching tube V2 is a lower bridge arm, the switching tubes V3 and V4 are serially connected to form a right bridge arm, the switching tube V3 is an upper bridge arm, and the switching tube V4 is a lower bridge arm; the H-bridge structure in the Y-axis direction is a left bridge arm formed by connecting V5 and V6 in series, wherein a switch tube V5 is an upper bridge arm, and a switch tube V6 is a lower bridge arm; the switching tubes V7 and V8 are connected in series to form a right bridge arm, wherein the switching tube V7 is an upper bridge arm, and the switching tube V8 is a lower bridge arm; the suspension winding is connected in series between the left bridge arm and the right bridge arm;

in the X-axis direction, the radial suspension error current delta i is temporarily collected at the rising edge of the PWM waveform_xJudging the radial suspension error current delta i_xAnd maintaining one PWM period; when the error signal value Δ i_xIf the polarity is positive, the upper switch tube V1 of the front bridge arm of the H-bridge power converter is kept on, the lower switch tube V2 is switched off, and the upper switch tube and the lower switch tube are conducted in a complementary mode in the period of time;

when the error signal value Δ i_xIf the polarity is negative, the upper switch tube V1 on the front bridge arm of the H-bridge power converter is kept off in the time period, the lower switch tube V2 is switched on, and the upper switch tube and the lower switch tube are in complementary conduction;

in the Y-axis direction, the radial suspension error current delta i is temporarily collected at the rising edge of the PWM waveform_yJudging the radial suspension error current delta i_yAnd maintaining one PWM period; when the error signal value Δ i_yIf the polarity is positive, the upper switch tube V5 of the front bridge arm of the H-bridge power converter is kept on, the lower switch tube V6 is switched off, and the upper switch tube and the lower switch tube are conducted in a complementary mode in the period of time;

when the error signal value Δ i_yIf the polarity is negative, the upper switch tube V5 on the front bridge arm of the H-bridge power converter is kept off in the time period, the lower switch tube V6 is switched on, and the upper switch tube and the lower switch tube are in complementary conduction;

and C-3, acquiring the error signal value of the radial suspension current in real time in the PWM time period in the X-axis direction through a formulaCalculate the H bridgeDuty ratio of switch tube V4 under rear arm of power converter when error signal value delta i_xThe polarity is positive, the duty ratio of a lower switch tube V4 of a rear bridge arm of the H-bridge power converter is calculated to be 1 through a formula, a lower switch tube V4 is fully turned on, an upper switch tube V3 is turned off, and the upper switch tube and the lower switch tube are in complementary conduction; when the error signal value Δ i_xThe polarity is negative, the duty ratio of a lower switching tube V4 of a rear bridge arm of the H-bridge power converter is calculated to be 0 through a formula, the lower switching tube V4 is turned off, and an upper switching tube V3 is turned on;

in a PWM period, the front bridge arm is in a conducting state with a switch V1, the rear bridge arm collects the error signal value of the suspension current in real time to calculate the duty ratio, and when the error signal value delta i is_xThe polarity is positive, the switch tube V4 under the rear bridge arm is switched on, the power supply voltage is positive charging of the suspension winding and is marked as a plus state, and when the error signal value delta i_xWhen the polarity is negative, the switching tube V4 under the rear bridge arm is turned off, and the suspension winding enters a follow current state and is marked as a '0' state;

in a PWM period, the front bridge arm is in a turn-off state with the switch V1, the rear bridge arm collects the error signal value of the suspension current in real time to calculate the duty ratio, and when the error signal value delta i_xWhen the polarity is negative, the switch tube V4 under the rear bridge arm is turned off, the switch tube V3 on the rear bridge arm is turned on, the power supply voltage is reverse charging of the suspension winding and is recorded as a negative state, and when the error signal value delta i_xWhen the polarity is positive, the rear-axle-arm lower switch tube V4 is switched on, and the suspension winding enters a follow current state, namely a '0' state; the three-level control mode can effectively reduce output current ripples and quickly follow a given current value; the method comprises the following steps that (1) conducting signals of all switching tubes of an H-bridge power converter are controlled to enable the switching tubes to give suspension current along the X-axis direction, and then suspension force in the X-axis direction is controlled;

collecting error signal value of radial suspension current in real time in PWM time period in Y-axis direction according to formulaCalculating the duty ratio of a switching tube V8 under the rear bridge arm of the H-bridge power converter, and calculating the duty ratio when the error signal value delta i_yThe polarity is positive, the duty ratio of a switching tube V8 under a rear bridge arm of the H-bridge power converter is 1 and is calculated by a formulaThe switch tube V8 is fully switched on, the upper switch tube V7 is switched off, and the upper switch tube and the lower switch tube are complementarily switched on; when the error signal value Δ i_yThe polarity is negative, the duty ratio of a lower switching tube V8 of a rear bridge arm of the H-bridge power converter is calculated to be 0 through a formula, the lower switching tube V8 is turned off, and an upper switching tube V7 is turned on;

in a PWM period, the front bridge arm is in a conducting state with a switch V5, the rear bridge arm collects the error signal value of the suspension current in real time to calculate the duty ratio, and when the error signal value delta i is_yThe polarity is positive, the switch tube V8 under the rear bridge arm is switched on, the power supply voltage is positive charging of the suspension winding and is marked as a plus state, and when the error signal value delta i_yWhen the polarity is negative, the switching tube V8 under the rear bridge arm is turned off, and the suspension winding enters a follow current state and is marked as a '0' state;

in a PWM period, the front bridge arm is in a turn-off state with the switch V5, the rear bridge arm collects the error signal value of the suspension current in real time to calculate the duty ratio, and when the error signal value delta i_yWhen the polarity is negative, the switch tube V8 under the rear bridge arm is turned off, the switch tube V7 on the rear bridge arm is turned on, the power supply voltage is reverse charging of the suspension winding and is recorded as a negative state, and when the error signal value delta i_yWhen the polarity is positive, the rear-axle-arm lower switch tube V8 is switched on, and the suspension winding enters a follow current state, namely a '0' state; the three-level control mode can effectively reduce output current ripples and quickly follow a given current value; the H-bridge power converter is enabled to give suspension current along the Y-axis direction by controlling conducting signals of all switching tubes of the H-bridge power converter, and then suspension force in the Y-axis direction is controlled;

by adopting the three-level pulse width modulation technology, the output current ripple of the electromagnetic bearing switch power amplifier can be greatly reduced, and the given current value can be quickly followed;

step D, obtaining a phase winding current reference value i of the switched reluctance motor during the phase torque excitation^*And opening angle theta_on；

D-1, calculating to obtain a rotor angular speed omega according to the rotor rotating speed;

d-2, comparing the rotor angular speed omega with a set reference angular speed omega to obtain a rotation speed difference delta omega;

step D-3, when omega is less than or equal to omega₀When the temperature of the water is higher than the set temperature,ω₀the set value of the critical angular speed is determined by the actual working condition of the motor; the rotating speed difference delta omega is obtained through a PI controller, and the phase winding current reference value i is obtained^*(ii) a Angle of closure theta_offIs constant, wherein theta_offThe value is determined by the structural form of the motor;

step D-4, when omega is larger than omega₀Then, the opening angle theta is obtained through the PI controller according to the rotating speed difference delta omega_onThe phase winding current is not controlled at this time.

Step E, adjusting the torque during phase torque excitation; the step E specifically comprises the following steps: step E-1, when omega is less than or equal to omega₀In time, the current chopping control method is used to make the actual current i of the phase winding track the reference value i of the current of the phase winding when the phase torque is excited^*Further adjusting the current i of the phase winding in real time to realize torque adjustment;

step E-2, when omega is larger than omega₀By using an angle position control method, the opening angle theta is dynamically adjusted_onTo achieve the regulation of the torque.

As shown in FIG. 5, in step B, the magnetically levitated switched reluctance motor co-excitation power converter comprises a power source u_sThe power supply comprises an electrolytic capacitor C1, six power switching tubes from a first power switching tube S1 to a sixth power switching tube S6, six fly-wheel diodes from a first fly-wheel diode VD1 to a sixth fly-wheel diode VD6, two power diodes from a first power diode VD7 and a second power diode VD8, a seventh fly-wheel diode VD9 and an eighth fly-wheel diode VD 10; wherein the power source u_sThe anode of the first power diode VD7 is connected with the anode of the first power diode VD10 and the cathode of the eighth fly-wheel diode VD 10; the cathode of the first power diode VD7 is connected with the cathode of the seventh freewheeling diode VD 9; the anode of the eighth flywheel diode VD10 is connected with the anode of a second power diode VD 8; the anode of the seventh freewheeling diode VD9 is respectively connected with the cathode of the second power diode VD8 and the input end of the electrolytic capacitor C1; the cathode of the second power diode VD8 is respectively connected with the anode of the seventh fly-wheel diode VD9, the input end of the electrolytic capacitor C1, the drain of the first power switch tube S1, the cathode of the first fly-wheel diode VD1, the drain of the third power switch tube S3, the cathode of the third fly-wheel diode VD3, and the third fly-wheel diode VD3The drain electrode of the five power switching tube VD5 and the cathode of the fifth fly-wheel diode VD 5;

power supply u_sThe negative electrode of the second power switch tube is respectively connected with the output end of the electrolytic capacitor C1, the anode of the second fly-wheel diode VD2, the source electrode of the second power switch tube S2, the anode of the fourth fly-wheel diode VD4, the source electrode of the fourth power switch tube S4, the anode of the sixth fly-wheel diode VD6 and the source electrode of the sixth power switch tube S6;

the source electrode of the first power switch tube S1 is connected with the cathode electrode of the second fly-wheel diode VD 2; the anode of the first freewheeling diode VD1 is connected with the drain of the second power switch tube S2; the source electrode of the third power switch tube S3 is connected with the cathode electrode of the fourth fly-wheel diode VD 4; the anode of the third freewheeling diode VD3 is connected with the drain of the fourth power switch tube S4; the source electrode of the fifth power switch tube S5 is connected with the cathode electrode of the sixth fly-wheel diode VD 6; the anode of the fifth freewheeling diode VD5 is connected with the drain of the sixth power switch tube S6;

a Bias inductance Bias of the magnetic bearing is connected in series between the cathode of the first power diode VD7 and the anode of the second power diode VD 8; an A-phase winding of the switched reluctance motor is connected in series between the source electrode of the first power switch tube S1 and the drain electrode of the second power switch tube; a B-phase winding of the switched reluctance motor is connected in series between the source electrode of the third power switch tube S3 and the drain electrode of the fourth power switch tube S4; the C-phase winding of the switched reluctance motor is connected in series between the source of the fifth power switching tube S5 and the drain of the sixth power switching tube S6.

As shown in FIG. 4, all the bias coils are connected in series to form a bias winding, the four coils on the narrower pole in the X-axis direction are connected in series to form an X-axis suspension winding, and similarly, the four coils on the narrower pole in the Y-axis direction are connected in series to form a Y-axis suspension winding, when the bias winding current i is used_biasGenerating a bias flux and levitating the winding current i by the X axis_xOr Y-axis levitation current i_yWhen the control magnetic flux is generated, radial force acting on the rotor along the X axis or the Y axis is generated respectively, and the control current i is used for controlling the radial force_xAnd i_yCan generate the required radial force in any radial direction.

Fig. 10 is a simulation comparison of output current waveforms of the method and the hysteresis control method, where a given input current is a sine wave as shown in fig. 9, and current waveforms output by the method and the hysteresis comparison method are 10 and 11 waveforms in the graph, respectively, and it can be seen that there are few current ripples by using the method and there are few ripples by using the method compared with ripples in the hysteresis control method, and the method can quickly follow the given sine current.

The invention can obviously improve the utilization rate of the armature winding current of the switched reluctance motor, reduce the cost of a magnetic bearing power system, simplify the difficulty of suspension force control, integrate a magnetic bearing bias winding power converter and a switched reluctance motor three-phase armature winding power converter into a whole, have high integration level, low cost and strong reliability, generate torque by an SRM (sequence-related modulation), adopt the traditional control mode in the control method, adopt a CCC (common control mode) control mode at low speed, adopt an APC (automatic control) control mode at high speed; the method comprises the steps of carrying out PID adjustment on displacement errors to obtain suspension force, obtaining bias current sampled by a co-excitation converter through finite element radial magnetic bearing current lookup to obtain given radial suspension current, controlling a conducting signal of a front bridge arm switch tube of the H-bridge power converter in one PWM period through suspension error current polarity judgment and calculating the occupation ratio of a rear bridge arm switch tube through a formula to realize three-level control, further controlling the radial suspension force and reducing suspension output current ripples.

Other advantages and modifications will readily occur to those skilled in the art, based upon the foregoing description. Therefore, the present invention is not limited to the above specific examples, and a detailed and exemplary description of one aspect of the present invention will be given by way of example only. It is intended that all technical equivalents which can be substituted by equivalents given to the above-described embodiments by those skilled in the art without departing from the scope and spirit of the present invention are encompassed by the claims and their equivalents.