CN115987087A - Electric power electronic controller for five-degree-of-freedom magnetic suspension bearing and control method - Google Patents

Abstract

The invention discloses an electric power electronic controller for a five-degree-of-freedom magnetic suspension bearing and a control method, and belongs to the field of magnetic suspension bearing control. The method comprises the following steps: eight controllable switches and eight one-way conduction devices, according to the one-way conduction devices and the connection mode of the controllable switches and the power supply, the eight bridge arms are divided into four forward bridge arms and four reverse bridge arms, the two forward bridge arms and the two reverse bridge arms are used as a group of bridge arms, in each group of bridge arms, the two forward bridge arms and the two reverse bridge arms are correspondingly connected with five windings, the fifth winding of each group of bridge arms is connected between every two windings in the first four windings, the current of each winding is controlled by changing the conduction time of each controllable switch, and only 8 bridge arms are used for controlling 10 windings. The invention reduces the complexity of the electric and electronic controller of the five-degree-of-freedom magnetic suspension bearing, simultaneously reduces the volume of the controller, realizes the reduction of the cost and has good practical application value.

Description

Electric power electronic controller for five-degree-of-freedom magnetic suspension bearing and control method

Technical Field

The invention belongs to the field of magnetic suspension bearing control, and particularly relates to an electronic power controller for a five-degree-of-freedom magnetic suspension bearing and a control method.

Background

The magnetic suspension bearing is used for suspending a rotor by using electromagnetic force so as to realize the non-contact operation of the rotor and a stator. The magnetic suspension bearing has the characteristics of no friction, no pollution, long service life and the like, and is suitable for high-speed, ultrahigh-speed and high-performance transmission occasions requiring no contact, no lubrication and no pollution. Foreign related products are started earlier, and have already entered the practical application stage since the last 70 th century; the research on the magnetic suspension bearing in China starts relatively late, but the related technology has been greatly improved through the development of the academic and industrial fields for decades, and products are gradually applied, such as magnetic suspension bearing flywheel energy storage, magnetic suspension centrifugal blowers and the like, so that the magnetic suspension bearing has a good application prospect.

For an active magnetic suspension bearing system, a set of control system is required to regulate and control the electromagnetic force of each winding. The power amplifier receives a control signal of the controller to convert the command current into an actual current, and is a key part in a control system. The rotor, which is the object of the magnetic bearing support, has 5 degrees of freedom, which determines that the magnetic bearing system is at least a 5-degree-of-freedom system. The magnetic suspension bearing has a large number of windings to be controlled due to multiple degrees of freedom, and a large number of power electronic devices and driving thereof are needed when the traditional full-bridge topological structure is used, so that the whole control system has a complex structure, a large volume and high cost. The existing students propose to reduce the number of power electronic devices by adopting a method of sharing a bridge arm, and 24 power electronic devices are needed for controlling 10 windings; or a shared bridge arm is omitted, so that 8 windings are controlled by 16 power electronic devices, and the rest 2 windings are controlled by adding 6 power electronic devices, and 22 power electronic devices are needed. The two modes still cannot optimize the number of devices globally, and both still need more power electronic devices, and the more power electronic devices make the whole control system have a complex structure, a large volume and high cost.

Disclosure of Invention

Aiming at the defects and improvement requirements of the prior art, the invention provides an electric power electronic controller for a five-degree-of-freedom magnetic suspension bearing and a control method thereof, and aims to reduce the complexity of the electric power electronic controller for the five-degree-of-freedom magnetic suspension bearing and reduce the size and cost of the controller.

To achieve the above object, according to one aspect of the present invention, there is provided an electronic power controller for a five-degree-of-freedom magnetic suspension bearing including ten windings divided into two groups of five windings denoted as first to fifth windings, the controller comprising:

the controllable bridge arms are divided into two groups, and four bridge arms in each group are marked as a first bridge arm, a second bridge arm and a third bridge arm; each winding, the controllable switch and the unidirectional conducting device respectively comprise a first end and a second end, the winding and the controllable switch take one end, into which current flows, as the first end, the end, out of which current flows, as the second end, the unidirectional conducting device takes one end, out of which current flows, as the first end, and the end, into which current flows, as the second end;

four bridge arms in each group are connected in parallel at two ends of a power supply, in the first bridge arm and the second bridge arm, the first end of a controllable switch is connected with the positive electrode of the power supply, the second end of the controllable switch is connected in series with the first end of a one-way conduction device, and the second end of the one-way conduction device is connected with the negative electrode of the power supply; in the third bridge arm and the fourth bridge arm, a first end of a one-way conduction device is connected to the anode of a power supply, a second end of the one-way conduction device is connected with a first end of a controllable switch in series, and a second end of the controllable switch is connected to the cathode of the power supply;

in each group of bridge arms, the middle points of the first bridge arm and the second bridge arm are respectively connected with the first ends of the first winding and the second winding, and the second ends of the first winding and the second winding are connected together in parallel and then connected with the first end of the fifth winding; the middle points of the third bridge arm and the fourth bridge arm are respectively connected with the second ends of the third winding and the fourth winding, and the first ends of the third winding and the fourth winding are connected together in parallel and then connected with the second end of the fifth winding.

Furthermore, the controllable switches are all active switch tubes, and the unidirectional conducting devices are all diodes.

Further, the active switch tube is an IGBT or a MOSFET.

Furthermore, the first end of the controllable switch is a collector of the IGBT, and the second end of the controllable switch is an emitter of the IGBT;

the first end of the unidirectional conducting device is the cathode of the diode, and the second end of the unidirectional conducting device is the anode of the diode.

Further, the current flowing through the winding is unidirectional.

According to a second aspect of the present invention, there is provided a control method for implementing the electronic power controller for a five-degree-of-freedom magnetic suspension bearing according to any one of the first aspects, comprising:

controlling the on-time duty ratio of the controllable switch to enable the controller to work in one of five basic working modes; for any one of the two groups of bridge arms, the five basic working modes include:

a first fundamental working mode: controlling the equivalent duty ratios of the middle points of the four bridge arms to be equal, so that the currents of the five windings are kept unchanged;

the second basic working mode is as follows: controlling the equivalent duty ratios of the middle points of the first bridge arm and the second bridge arm to be equal and higher than the equivalent duty ratios of the middle points of the third bridge arm and the fourth bridge arm so as to increase the sum of the currents of the first winding and the second winding and the sum of the currents of the third winding and the fourth winding;

the third basic working mode: controlling the equivalent duty ratios of the middle points of the third bridge arm and the fourth bridge arm to be equal and higher than the equivalent duty ratios of the middle points of the first bridge arm and the second bridge arm so as to reduce the sum of the currents of the first winding and the second winding and the sum of the currents of the third winding and the fourth winding;

a fourth basic working mode: controlling the equivalent duty ratio of the middle points of the first bridge arm and the second bridge arm to change the difference between the currents of the first winding and the second winding;

a fifth basic working mode: controlling the electric equivalent duty ratio in the third bridge arm and the fourth bridge arm to change the current difference of the third winding and the fourth winding;

the equivalent duty ratios of the middle points of the first bridge arm and the second bridge arm are consistent with the on-time duty ratios of the controllable switches in the first bridge arm and the second bridge arm, and the sum of the equivalent duty ratios of the middle points of the third bridge arm and the fourth bridge arm and the on-time duty ratios of the controllable switches in the third bridge arm and the fourth bridge arm is 1.

Further, in the fourth fundamental working modality, the method includes:

controlling the midpoint equivalent duty ratio of the first bridge arm to be higher than that of the second bridge arm so as to increase the difference between the currents of the first winding and the second winding;

or controlling the equivalent duty ratios of the middle points of the first bridge arm and the second bridge arm to be equal, so that the current difference between the first winding and the second winding is constant;

or the equivalent duty ratio of the midpoint of the first bridge arm is controlled to be lower than that of the midpoint of the second bridge arm, so that the difference between the currents of the first winding and the second winding is reduced.

Further, the fifth fundamental working mode includes:

controlling the equivalent duty ratio of the midpoint of the third bridge arm to be higher than that of the midpoint of the fourth bridge arm, so that the difference between the currents of the third winding and the fourth winding is reduced;

or the equivalent duty ratios of the middle points of the third bridge arm and the fourth bridge arm are controlled to be equal, so that the current difference between the third winding and the fourth winding is constant;

or the equivalent duty ratio of the middle point of the third bridge arm is controlled to be lower than that of the middle point of the fourth bridge arm, so that the difference between the currents of the third winding and the fourth winding is increased.

Further, the method also comprises controlling the on-time duty ratio of the controllable switch to enable the controller to work in two or more of the five basic working modes simultaneously, wherein the control between the two or more basic working modes is not conflicted.

Further, the controller operates in a second basic operating mode and a fifth basic operating mode simultaneously;

or the controller simultaneously works in a third basic working mode and a fourth basic working mode;

or the controller works in a fourth basic working mode and a fifth basic working mode simultaneously.

Generally, by the above technical solution conceived by the present invention, the following beneficial effects can be obtained:

(1) The controller of the invention divides eight bridge arms into four forward bridge arms and four reverse bridge arms according to the connection mode of the one-way conduction device and the controllable switch and the power supply, the two forward bridge arms and the two reverse bridge arms are taken as a group of bridge arms, in each group of bridge arms, the middle points of the two forward bridge arms are connected with the first ends of a first winding and a second winding, the middle points of the two reverse bridge arms are connected with the second ends of a third winding and a fourth winding, the second ends of the first winding and the second winding are connected together in parallel and then connected with the first end of a fifth winding, the first ends of the third winding and the fourth winding are connected in parallel and then connected with the second end of the fifth winding, the current of each winding connected with each bridge arm can be controlled by changing the conduction time of each controllable switch, and the current of the corresponding fifth winding in each group of bridge arms can be controlled by controlling the current flowing into each group of bridge arms based on the connection relation of the fifth winding, so that the control of the electromagnetic force generated by 10 windings in the five-degree-of-freedom magnetic suspension bearing is realized. Compared with the conventional five-degree-of-freedom magnetic suspension bearing controller, the five-degree-of-freedom magnetic suspension bearing controller has the advantages that the fifth winding of each group of bridge arms is connected between every two windings of the first four windings, the bridge arms for controlling the fifth windings of the two groups of windings are omitted, only 8 bridge arms are needed to control 10 windings, the number of power electronic devices in the five-degree-of-freedom magnetic suspension bearing controller is greatly reduced, the complexity of a power electronic controller of the five-degree-of-freedom magnetic suspension bearing is reduced, the size of the controller is reduced, the cost is reduced, and the five-degree-of-freedom magnetic suspension bearing controller has good practical application value.

(2) Further, based on the controller provided by the invention, the invention also provides a corresponding control method of the controller, and the on-time duty ratio of the controllable switching device on each bridge arm is controlled simultaneously, so that the controller works in different working modes, and each mode can work independently or cooperate with each other, and the control of the charging and discharging time and the follow current time of each winding is realized, thereby realizing the control of the current of each winding, further completing the control of the electromagnetic force in the five-degree-of-freedom magnetic suspension bearing, and meeting the actual application requirements

In summary, the electronic power controller and the control method of the invention can further reduce the number of electronic power devices in the magnetic suspension bearing controller, reduce the complexity of the electronic power controller of the five-degree-of-freedom magnetic suspension bearing, and reduce the volume and cost of the controller.

Drawings

FIG. 1 is a schematic structural diagram of a five-degree-of-freedom magnetic suspension bearing provided by an embodiment of the invention;

FIG. 2 is a schematic diagram of a single radial magnetic suspension bearing structure provided by an embodiment of the invention;

FIG. 3 is a topology diagram of a five degree of freedom magnetic bearing power electronic controller provided by an embodiment of the invention;

FIG. 4 (a) illustrates a first fundamental mode of operation of a controller according to an embodiment of the present invention;

FIG. 4 (b) illustrates a second fundamental mode of operation of the controller provided in accordance with an embodiment of the invention;

FIG. 4 (c) illustrates a third fundamental mode of operation of the controller provided in accordance with an embodiment of the present invention;

FIG. 4 (d) shows a fourth basic operating mode of the controller according to an embodiment of the present invention;

FIG. 4 (e) shows a fifth basic mode of operation of the controller according to an embodiment of the present invention;

FIG. 5 is a control schematic diagram of a single sub-set winding current invariance provided by an embodiment of the present invention;

FIG. 6 is a schematic diagram of the control of the overall rise in current for a single subset winding provided by an example of the present invention;

FIG. 7 is a schematic diagram of the control of the total drop in current for a single subset winding provided by an embodiment of the present invention;

fig. 8 (a) is a schematic control diagram of current changes of the first to fourth windings corresponding to a set of bridge arms according to an embodiment of the present invention;

fig. 8 (b) is a schematic diagram illustrating a control of a fifth winding by changing currents of first to fourth windings corresponding to a set of bridge arms according to an embodiment of the present invention;

fig. 9 is a schematic control diagram for stable suspension of a five-degree-of-freedom magnetic suspension bearing according to an embodiment of the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the respective embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

In the present invention, the terms "first", "second", and the like in the description and the drawings are used for distinguishing similar objects, and are not necessarily used for describing a particular order or sequence.

As shown in fig. 1, the structure of a five-degree-of-freedom magnetic suspension bearing is shown, the five-degree-of-freedom magnetic suspension bearing system controls a rotor to achieve complete suspension, 2 radial magnetic suspension bearings and 1 axial magnetic suspension bearing are required, 5-degree-of-freedom force and 10 winding currents need to be controlled, and coupling exists between the degrees of freedom.

As shown in fig. 2, a structure diagram of a single radial magnetic bearing is shown. The radial magnetic suspension bearing structure has electromagnetic force F in the x direction _x Electromagnetic force F in the opposite direction of y _y Control is required. Wherein the electromagnetic force F in the x-direction _x Determined by the difference in the electromagnetic forces generated by the 2 windings in the x-direction and the electromagnetic force F in the y-direction _y Determined by the difference in the electromagnetic forces generated by the 2 windings in the y-direction.

Magnitude of electromagnetic force F generated by each winding to the rotor _mag Excitation current i to the winding _s And the relative distance s between the winding and the rotor satisfies F _mag ＝K _i ×i _s -K _s s, wherein K _i Is the electromagnetic force/current coefficient, K _s Is the electromagnetic force/displacement coefficient, K _i And K _s Is determined by the structure of the radial winding of the magnetic suspension bearing.

Taking a single degree of freedom as an example, the control usually adopts double-loop control, the outer loop is a position loop, the inner loop is a current loop, the relative position of the displacement sensor and the rotor is used as the feedback of the position loop, the feedback is compared with a given position, the exciting current command signal of the inner loop winding is given out through a controller, the tracking of actual current to command current is realized through the current loop, and the effective control of electromagnetic force of each degree of freedom is realized. The command current is distributed in a differential control mode, and the command currents of the pair of windings controlling one degree of freedom are respectively the addition and subtraction of the bias current and the control current.

As shown in fig. 3, a structural schematic diagram of an electronic controller for a five-degree-of-freedom magnetic suspension bearing according to an embodiment of the present invention is provided, where the five-degree-of-freedom magnetic suspension bearing includes ten windings, the ten windings are divided into two groups, five windings in each group are respectively denoted as a first winding, a second winding, a third winding, a fourth winding, and a fifth winding, currents of the ten windings are unidirectional, each winding includes a first end and a second end, one end of the winding where a current flows is used as the first end, and one end of the winding where a current flows is used as the second end;

the electronic controller of the five-freedom magnetic suspension bearing mainly comprises: the eight bridge arms are divided into two groups, and the two groups of bridge arms are respectively and correspondingly connected with the two groups of windings; recording a connection point of each controllable switch and each one-way conduction device in series connection as a midpoint of a corresponding bridge arm, wherein each controllable switch and each one-way conduction device comprises a first end and a second end, and regarding the winding and the controllable switch, one end where current flows in is taken as the first end, one end where the current flows out is taken as the second end, regarding the one-way conduction device, one end where the current flows out is taken as the first end, and one end where the current flows in is taken as the second end;

in each group of bridge arms, four bridge arms are connected in parallel at two ends of a power supply, and the four bridge arms are respectively a first bridge arm, a second bridge arm, a third bridge arm and a fourth bridge arm; in the first bridge arm and the second bridge arm, a first end of a controllable switch is connected with a positive electrode of a power supply, a second end of the controllable switch is connected with a first end of a one-way conduction device in series, and a second end of the one-way conduction device is connected with a negative electrode of the power supply; in the third bridge arm and the fourth bridge arm, a first end of a one-way conduction device is connected to the positive electrode of a power supply, a second end of the one-way conduction device is connected with a first end of a controllable switch in series, and a second end of the controllable switch is connected to the negative electrode of the power supply;

through the connection relation, the formed first bridge arm and the second bridge arm are forward bridge arms, and the third bridge arm and the fourth bridge arm are reverse bridge arms;

the midpoint of the first bridge arm is connected with the first end of the first winding, the midpoint of the second bridge arm is connected with the first end of the second winding, and the second end of the first winding and the second end of the second winding are connected in parallel and then connected to the first end of the fifth winding;

the midpoint of the third bridge arm is connected with the second end of the third winding, the midpoint of the fourth bridge arm is connected with the second end of the fourth winding, and the first end of the third winding and the first end of the fourth winding are connected together in parallel and then connected to the second end of the fifth winding.

And controlling the conduction time of the controllable switch to meet the condition that the sum of the currents of the first winding and the second winding connected to the middle points of the first bridge arm and the second bridge arm is equal to the sum of the currents of the third winding and the fourth winding connected to the middle points of the third bridge arm and the fourth bridge arm.

To better illustrate the solution proposed by the present invention, the following analysis is directed to a five-degree-of-freedom magnetic suspension bearing and an optimized winding layout of the five-degree-of-freedom magnetic suspension bearing to which the present invention is applied. However, the controller proposed by the present invention is not limited to the winding layout shown in the drawings of the present embodiment, and in the controllable switch, the unidirectional conducting device and the winding connection mode determined by the present invention, different control requirements can be satisfied by reasonably adjusting the layout of the winding.

Fig. 3 is a topological diagram of an electronic power controller for a five-degree-of-freedom magnetic suspension bearing according to an embodiment of the present invention, and indicates winding distribution and reference directions of winding currents, which correspond to the winding distribution in fig. 1. In the first group of bridge arms, the first winding corresponds to the winding L in the positive direction of the front end radial magnetic bearing x _a1 The second winding corresponds to the winding L in the negative direction of the front radial magnetic bearing x _c1 The third winding corresponds to the winding L on the positive direction of the front radial magnetic bearing y _a2 The fourth winding corresponds to the winding L in the negative direction of the radial magnetic bearing y at the front end _c2 The fifth winding corresponds to the winding L in the positive z direction of the axial magnetic bearing _a5 . In the second group of bridge arms, the first winding corresponds to the winding L on the positive direction of the radial magnetic bearing x at the rear end _a3 The second winding corresponds to the winding L in the negative direction of the rear radial magnetic bearing x _c3 The third winding corresponds to the winding L on the positive direction of the rear radial magnetic bearing y _a4 The fourth winding corresponds to the winding L in the y negative direction of the rear radial magnetic bearing _c4 The fifth winding corresponds to the winding L in the z-negative direction of the axial magnetic bearing _c5 。

Specifically, in the first group of bridge arms, a first end of the controllable switch S11 is connected to the positive electrode of the power supply, a second end of the controllable switch S11 is connected to a first end of the one-way conduction device D11, and a second end of the one-way conduction device D11 is connected to the negative electrode of the power supply, so as to form a forward bridge arm;

in the first group of bridge arms, a first end of a controllable switch S12 is connected to the positive electrode of a power supply, a second end of the controllable switch S12 is connected to a first end of a one-way conduction device D12, and a second end of the one-way conduction device D12 is connected to the negative electrode of the power supply, so that a forward bridge arm is formed;

in the first group of bridge arms, a first end of a one-way conduction device D13 is connected to the positive pole of a power supply, a second end of the one-way conduction device D13 is connected to a first end of a controllable switch S13, and a second end of the controllable switch S13 is connected to the negative pole of the power supply to form a reverse bridge arm;

in the first group of bridge arms, a first end of a one-way conduction device D14 is connected to the positive pole of a power supply, a second end of the one-way conduction device D14 is connected to a first end of a controllable switch S14, and a second end of the controllable switch S14 is connected to the negative pole of the power supply to form a reverse bridge arm;

in the first set of legs, the first winding L _a1 Is connected to the midpoint of the first leg, a second winding L _c1 Is connected to the midpoint of the second leg, a first winding L _a1 And a second winding L _c1 Are connected together and to the fifth winding L _a5 A first end of (a); third winding L _a2 Is connected to the midpoint of the third leg, a fourth winding L _c2 Is connected to the midpoint of the fourth leg, a third winding L _a2 And a fourth winding L _c2 Are connected together and to the fifth winding L _a5 A second end of (a).

A controllable switch S21, a controllable switch S22, a controllable switch S23, a controllable switch S24, a one-way conducting device D21, a one-way conducting device D22, a one-way conducting device D23, a one-way conducting device D24 and five other windings L in the power electronic device in the second group of bridge arms _a3 、L _c3 、L _a4 、L _c4 、L _c5 The connection mode of (a) is consistent with that of the first set of bridge arms.

Aiming at the power electronic controller of the five-degree-of-freedom magnetic suspension bearing, the invention also provides a control method corresponding to the controller, the current of the corresponding winding can be controlled by controlling the conduction time of the controllable switch in each bridge arm, and the current of the fifth winding in each group of windings is controlled by controlling the current flowing into the first group of bridge arms and the second group of bridge arms, so that the control of the electromagnetic force generated by the ten windings in the five-degree-of-freedom magnetic suspension bearing is realized.

The control modes of the first set of bridge arms and the second set of bridge arms are completely the same, and the present embodiment is described by controlling 2 forward bridge arms and 2 reverse bridge arms in the first set of bridge arms and corresponding 5 windings.

The first winding L is controlled by the switch tube S11 _a1 Level of the first terminal: s11, when conducting, the first winding L _a1 The first end of the power supply is connected with the positive electrode of the power supply; when S11 is turned off, winding L _a1 Is connected to the negative pole of the power supply. Second winding L _c1 And the first windingL _a1 The control principle is the same.

The third winding L is controlled by a switching tube S13 _a2 Level of the first terminal: s13, when conducting, the third winding L _a2 The first end of the power supply is connected with the positive electrode of the power supply; when S13 is turned off, the third winding L _a2 Is connected to the negative pole of the power supply. Fourth winding L _c2 And the third winding L _a2 The control principle is the same.

The circuit can work in different working modes by controlling the on-time duty ratios of S11, S12, S13 and S14, the equivalent circuit in different working modes is shown in fig. 4 (a) -4 (e), the equivalent duty ratio of the midpoint of the forward bridge arm is consistent with the on-time duty ratio of the switching device in the forward bridge arm, and the sum of the equivalent duty ratio of the midpoint of the reverse bridge arm and the on-time duty ratio of the switching device in the reverse bridge arm is 1;

fig. 4 (a) shows an equivalent circuit of a first basic operation mode, which is used for controlling the current in all windings to be constant: and controlling the equivalent duty ratios of the middle points of all the bridge arms to be equal, wherein no potential difference exists between the first ends of the first and second windings and the second ends of the third and fourth windings, and the currents in the five windings are almost unchanged.

Fig. 4 (b) shows an equivalent circuit of the second fundamental operating mode: the equivalent duty ratios of the midpoints of the two forward bridge arms are controlled to be equal and higher than the equivalent duty ratios of the midpoints of the two reverse bridge arms, relative to the current direction, both ends of two windings (namely a first winding and a second winding) corresponding to the forward bridge arms are respectively provided with positive voltage, the sum of the currents of the first winding and the second winding is increased, and the sum of the currents of the third winding and the fourth winding is increased.

Fig. 4 (c) shows an equivalent circuit of the third fundamental operating mode: and controlling the equivalent duty ratios of the midpoints of the two reverse bridge arms to be equal and higher than the equivalent duty ratios of the midpoints of the two forward bridge arms, and controlling the two ends of two windings (namely, a third winding and a fourth winding) corresponding to the reverse bridge arms to be negative voltages relative to the current direction, wherein the sum of the currents of the first winding and the second winding is reduced, and the sum of the currents of the third winding and the fourth winding is reduced.

Fig. 4 (d) shows an equivalent circuit of a case in the fourth basic operating mode, that is, the equivalent duty ratio of the midpoint of one forward bridge arm is higher than that of the midpoint of the other forward bridge arm, and with respect to the current direction of the winding, the voltage at two ends of the winding connected to the midpoint of the forward bridge arm with the high equivalent duty ratio of the midpoint of the bridge arms is higher than the voltage at two ends of the winding connected to the midpoint of the other forward bridge arm, and at this time, the difference between the currents of the winding connected to the midpoint of the forward bridge arm with the high equivalent duty ratio and the winding connected to the midpoint of the forward bridge arm with the low equivalent duty ratio increases; taking the example that the equivalent duty ratio of the midpoint of the first bridge arm is higher than that of the midpoint of the second bridge arm, relative to the current direction of the winding, the voltage at two ends of the first winding is higher than that at two ends of the second winding, and at the moment, the difference between the currents of the first winding and the second winding is increased. In practical application, the equivalent duty ratio of the midpoint of one forward bridge arm can be controlled to be equal to the equivalent duty ratio of the midpoint of the other forward bridge arm, so that the difference between the currents of the first winding and the second winding is kept unchanged; or the equivalent duty ratio of the midpoint of one forward bridge arm is controlled to be lower than that of the midpoint of the other forward bridge arm, so that the difference between the currents of the first winding and the second winding is reduced.

Fig. 4 (e) shows an equivalent circuit of a case in a fifth basic operation mode, in which the equivalent duty ratio of the midpoint of one reverse bridge arm is higher than that of the midpoint of the other reverse bridge arm, and the voltage across the winding connected to the midpoint of the reverse bridge arm having the higher equivalent duty ratio of the midpoint of the bridge arms is lower than that of the winding connected to the midpoint of the other reverse bridge arm with respect to the current direction of the winding, and at this time, the difference between the currents of the winding connected to the midpoint of the reverse bridge arm having the higher equivalent duty ratio and the winding connected to the midpoint of the reverse bridge arm having the lower equivalent duty ratio is reduced; taking the example that the equivalent duty ratio of the midpoint of the third bridge arm is higher than that of the midpoint of the fourth bridge arm, relative to the current direction of the winding, the voltage of two ends of the third winding is lower than that of two ends of the fourth winding, and at the moment, the difference between the currents of the third winding and the fourth winding is reduced. In practical application, the equivalent duty ratio of the middle point of one reverse bridge arm can be controlled to be equal to the equivalent duty ratio of the middle point of the other reverse bridge arm, so that the difference between the currents of the third winding and the fourth winding is kept unchanged; or the equivalent duty ratio of the middle point of one reverse bridge arm is controlled to be lower than that of the middle point of the other reverse bridge arm, so that the difference between the currents of the third winding and the fourth winding is increased.

In any one of the five basic working modes, the current of the fifth winding is always equal to the sum of the currents of the first winding and the second winding and the sum of the currents of the third winding and the fourth winding. The sum of the currents of the 2 windings connected to the midpoint of the forward bridge arm is always equal to the sum of the currents of the 2 windings connected to the midpoint of the reverse bridge arm, and is equal to the current flowing through the fifth winding, the current value changes in real time in the working process, and the current value is determined by the control requirement of the fifth winding.

The control method ensures that the current flowing through the five-degree-of-freedom magnetic suspension bearing winding is unidirectional.

According to actual control requirements, the five basic working modes can work independently, and the 5 basic working modes can also be combined in a superposition manner without conflict to realize more complex control requirements, for example, the second basic working mode and the fifth basic working mode can be combined with each other, the third basic working mode and the fourth basic working mode can be combined with each other, the fourth basic working mode and the fifth basic working mode can be combined with each other to realize that required voltage is applied to two ends of corresponding windings, and further control over the size of the winding current is realized.

The working mode and the control principle of the second group of bridge arms are completely consistent with those of the first group of bridge arms, and the corresponding basic working mode can be selected or different basic working modes can be combined with each other without conflict according to actual control requirements, so that the control of the current of all windings is realized.

Fig. 5 shows a case where the current is almost unchanged in the first basic working mode, at this time, the equivalent duty ratios of the middle points of the bridge arms are the same, where the current of the fifth winding is equal to the sum of the currents of the first and second windings, and therefore, the current is also unchanged; in the figure, g11, g12, g13 and g14 respectively represent the on and off states of the switch tubes S11, S12, S13 and S14, a high level represents that the corresponding switch tube is on, a low level represents that the corresponding switch tube is off, and i11, i12, i13 and i14 represent the current passing through the corresponding winding.

Fig. 6 shows the case where the winding currents are all increased in the second fundamental operating mode, in which the current of the fifth winding is equal to the sum of the currents of the first and second windings, and is therefore also increased;

fig. 7 shows the case where the winding current is reduced in total in the third basic operating mode, in which the current of the fifth winding is equal to the sum of the currents of the first and second windings and is therefore also reduced;

fig. 8 (a) shows a case where a winding current connected to a midpoint of one forward leg increases, a winding current connected to a midpoint of the other forward leg decreases, a winding current connected to a midpoint of the reverse leg increases, and a winding current connected to a midpoint of the other reverse leg decreases when the fourth basic operating mode and the fifth basic operating mode are superimposed;

fig. 8 (b) shows the situation that the current of the fifth winding in the subset is kept unchanged under the superposition of the fourth basic operation mode and the fifth basic operation mode.

For a five-degree-of-freedom magnetic suspension bearing, the control method belongs to a novel differential control mode, the sum of the currents of 2 windings in the x direction of the front-end magnetic bearing is equal to the sum of the currents of 2 windings in the y direction of the front-end magnetic bearing, the sum of the currents of 2 windings in the x direction of the rear-end magnetic bearing is equal to the sum of the currents of 2 windings in the y direction of the rear-end magnetic bearing, and the sum of the currents of 2 windings of the axial magnetic bearing is a certain value. Meanwhile, according to the control method, the magnitude value of the sum of the currents of the pair of windings controlling the same degree of freedom can be determined according to needs, and the magnitude difference value of the currents determines the magnitude of the electromagnetic force on the degree of freedom, so that the sum of the currents of the first winding and the second winding in each group of bridge arms is equal to the sum of the currents of the third winding and the fourth winding, and the sum of the currents of the first winding and the second winding in the two groups of bridge arms can be determined according to actual needs.

With the aid of the control mode, the electric power electronic controller for the five-degree-of-freedom magnetic suspension bearing provided by the invention can complete the stable suspension of the five-degree-of-freedom magnetic suspension bearing, and a stable suspension result is shown in fig. 9.

All the controllable switches are active switch tubes, the unidirectional conducting devices are diodes, and control signals of the active switch tubes are pulse modulation signals with adjustable duty ratios.

The control of the winding current is realized by adjusting the conduction time of each active switch tube, so that the control of the electromagnetic force is realized.

Preferably, the active switch tube is an IGBT or a MOSFET, in this embodiment, the eight controllable switches are all Insulated Gate Bipolar Transistors (IGBTs), the eight unidirectional conducting devices are all diodes, a first end of each controllable switch is a collector of each Insulated Gate Bipolar Transistor, a second end of each controllable switch is an emitter of each Insulated Gate Bipolar Transistor, a first end of each unidirectional conducting device is a cathode of each diode, and a second end of each unidirectional conducting device is an anode of each diode.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims (10)

1. An electronic power controller for a five-degree-of-freedom magnetic suspension bearing, the five-degree-of-freedom magnetic suspension bearing comprising ten windings, the ten windings being equally divided into two groups, five windings in each group being marked as first to fifth windings, the controller comprising:

the controllable switch and the one-way conduction device are connected in series to form a bridge arm, the formed eight bridge arms are divided into two groups, and four bridge arms in each group are marked as a first bridge arm, a second bridge arm and a third bridge arm; each winding, the controllable switch and the unidirectional conducting device respectively comprise a first end and a second end, the winding and the controllable switch take one end, into which current flows, as the first end, the end, out of which current flows, as the second end, the unidirectional conducting device takes one end, out of which current flows, as the first end, and the end, into which current flows, as the second end;

four bridge arms in each group are connected in parallel at two ends of a power supply, in the first bridge arm and the second bridge arm, the first end of the controllable switch is connected with the anode of the power supply, the second end of the controllable switch is connected with the first end of the one-way conduction device in series, and the second end of the one-way conduction device is connected with the cathode of the power supply; in the third bridge arm and the fourth bridge arm, a first end of a one-way conduction device is connected to the anode of a power supply, a second end of the one-way conduction device is connected with a first end of a controllable switch in series, and a second end of the controllable switch is connected to the cathode of the power supply;

in each group of bridge arms, the middle points of the first and second bridge arms are respectively connected with the first ends of the first and second windings, and the second ends of the first and second windings are connected in parallel and then connected with the first end of the fifth winding; the middle points of the third bridge arm and the fourth bridge arm are respectively connected with the second ends of the third winding and the fourth winding, and the first ends of the third winding and the fourth winding are connected together in parallel and then connected with the second end of the fifth winding.

2. The controller of claim 1, wherein the controllable switches are all active switching tubes, and the unidirectional conducting devices are all diodes.

3. The controller of claim 2, wherein the active switching tube is an IGBT or a MOSFET.

4. A controller according to claim 3, wherein the first terminal of the controllable switch is a collector of an IGBT and the second terminal is an emitter of an IGBT;

the first end of the unidirectional conducting device is the cathode of the diode, and the second end of the unidirectional conducting device is the anode of the diode.

5. The controller of claim 1, wherein the current flowing through the winding is unidirectional.

6. A control method for realizing an electronic power controller for a five-degree-of-freedom magnetic suspension bearing as claimed in any one of claims 1 to 5, comprising:

controlling the on-time duty ratio of the controllable switch to enable the controller to work in one of five basic working modes; for any one of the two groups of bridge arms, the five basic working modes include:

a first fundamental working mode: controlling the equivalent duty ratios of the midpoints of the four bridge arms to be equal, and keeping the currents of the five windings unchanged;

a second fundamental working mode: controlling the equivalent duty ratios of the middle points of the first bridge arm and the second bridge arm to be equal and higher than the equivalent duty ratios of the middle points of the third bridge arm and the fourth bridge arm so as to increase the sum of the currents of the first winding and the second winding and the sum of the currents of the third winding and the fourth winding;

a third basic working mode: controlling the equivalent duty ratios of the middle points of the third and fourth bridge arms to be equal and higher than the equivalent duty ratios of the middle points of the first and second bridge arms, so that the sum of the currents of the first and second windings and the sum of the currents of the third and fourth windings are reduced;

a fourth basic working mode: controlling the equivalent duty ratio of the middle points of the first bridge arm and the second bridge arm to change the current difference of the first winding and the second winding;

a fifth basic working mode: controlling the electric equivalent duty ratio in the third bridge arm and the fourth bridge arm to change the current difference of the third winding and the fourth winding;

the equivalent duty ratios of the middle points of the first bridge arm and the second bridge arm are consistent with the on-time duty ratios of the controllable switches in the first bridge arm and the second bridge arm, and the sum of the equivalent duty ratios of the middle points of the third bridge arm and the fourth bridge arm and the on-time duty ratios of the controllable switches in the third bridge arm and the fourth bridge arm is 1.

7. The control method according to claim 6, wherein the fourth fundamental operating modality includes:

controlling the midpoint equivalent duty ratio of the first bridge arm to be higher than that of the second bridge arm so as to increase the difference between the currents of the first winding and the second winding;

or the equivalent duty ratios of the middle points of the first bridge arm and the second bridge arm are controlled to be equal, so that the current difference between the first winding and the second winding is constant;

or the equivalent duty ratio of the midpoint of the first bridge arm is controlled to be lower than that of the midpoint of the second bridge arm, so that the difference between the currents of the first winding and the second winding is reduced.

8. The control method according to claim 6, wherein the fifth fundamental operating mode comprises:

controlling the equivalent duty ratio of the midpoint of the third bridge arm to be higher than that of the midpoint of the fourth bridge arm, so that the difference between the currents of the third winding and the fourth winding is reduced;

or the equivalent duty ratios of the middle points of the third bridge arm and the fourth bridge arm are controlled to be equal, so that the current difference between the third winding and the fourth winding is constant;

or the equivalent duty ratio of the middle point of the third bridge arm is controlled to be lower than that of the middle point of the fourth bridge arm, so that the difference between the currents of the third winding and the fourth winding is increased.

9. The control method of claim 6, further comprising controlling the on-time duty cycle of the controllable switch to cause the controller to operate in two or more of the five fundamental operating modes simultaneously, wherein control between the two or more fundamental operating modes is non-conflicting.

10. The control method of claim 9, wherein the controller operates in a second fundamental operating mode and a fifth fundamental operating mode simultaneously;

or the controller simultaneously works in a third basic working mode and a fourth basic working mode;

or the controller works in a fourth basic working mode and a fifth basic working mode simultaneously.

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