CN102843053A - Three-dimensional spatial vector based switch power amplifier of magnetic bearing system - Google Patents

Abstract

The invention discloses a three-dimensional spatial vector based switch power amplifier of a magnetic bearing system. The three-dimensional spatial vector based switch power amplifier is a device for actively controlling current in a magnetic bearing coil, and mainly comprises a controller, an isolating driving circuit, a four-leg power main circuit, a current feedback detecting circuit, a signal conditioning circuit and a signal filtering circuit. According to a digital switch power amplifier, after the error of a current sampling value and a current desired value is calculated by using a controller and the real-time dead zone amendment is carried out, the PWM (pulse-width modulation) modulation based on a three-dimensional spatial vector is carried out; and furthermore, the on-off of power switch tubes in the four-leg power main circuit is controlled by using a PWM signal (obtained from the modulation) through the isolating driving circuit, so that the purpose of controlling the current of the magnetic bearing coil is achieved. According to the invention, the digital switch power amplifier which is applicable to the magnetic bearing control system is realized; the number of the power switch tubes and the amplitude of output ripple current are reduced; and the loss of an electromagnetic bearing is reduced.

Description

A kind of magnetic bearing system switch power amplifier based on three-dimensional space vectors

Technical field

The present invention relates to a kind of switch power amplifier, is a kind of switch power amplifier of the magnetic bearing system based on three-dimensional space vectors, is used for the output current of magnetic bearing coil is carried out ACTIVE CONTROL.

Background technology

The high-speed magnetic levitation motor is owing to adopt magnetic suspension bearing to replace traditional mechanical bearing, and advantages such as having the rotating speed height, do not have friction, need not to lubricate, energy density is high, size is little has broad application prospects.Power amplifier is as the actuator of high-speed magnetic levitation motor magnetic bearing control system, and its energy consumption is maximum, and the energy loss, raising integrated level, the increase reliability that reduce power amplifier are one of main purposes of Designing power amplifier.

In order to improve the efficient of power amplifier, high-speed magnetic levitation motor magnetic bearing control system generally adopts switch power amplifier.The implementation that produces circuit according to pulse width modulating signal is different, and magnetic bearing is divided into switch power amplifier that analogue device is realized and two kinds of Digital Implementation.The many employings of existing magnetic bearing control system power amplifier full bridge structure shown in Figure 1 adopts two traditional level PWM pulse duration modulation method output current ripples very big, in electromagnetic bearing, produces bigger iron loss and copper loss.

At Chinese patent " ZL200510012131.2 " disclosed " a kind of low-ripple switch power amplifier that is used for permanent magnet biased electromagnetic-bearing ", adopt analogue device to realize the function of three-level pwm pulse-width modulation, reduced the ripple loss; But the power amplifier loss of adopting analogue device to build is big, volume is bigger, simultaneously if will change the PWM modulation system must carry out hardware adjustment, uses inconvenient.

At Chinese patent " 200610114390.0 " disclosed " a kind of switch power amplifier that is used for magnetic suspension flywheel magnetic bearing system ", employing FPGA+DSP is a controller, adopts ternary PWM modulation system, and data-handling capacity is strong, and current ripples is little; But it need be connected in series noninductive power resistor respectively at following two power switch pipe source electrodes of bridge with between with reference to ground, when being controlled at the loop afterflow through FPGA current signal is sampled, and control mode is complicated, and programming realizes difficulty.

Above-mentioned two patents all adopt full bridge structure, and controlling a coil all needs 4 power switch pipes, realize the magnetic bearings control of 5 coils, needs 20 power tubes, causes volume and loss all to increase to some extent.

At Chinese patent " 200710120705.7 " disclosed " a kind of switch power amplifier that is used for magnetic bearing system based on space vector "; Adopt three brachium pontis structures shown in Figure 2 as main circuit, adopt FPGA+DSP, utilize the two-dimensional space vector modulation method as controller; Greatly reduce the current ripples loss; And middle brachium pontis is public by two magnetic bearing coil institutes, has reduced the quantity of power switch pipe, has reduced the volume of power amplifier; But its switching tube quantity is still more, and the power amplifier volume is still bigger, if further reduce the quantity of switching tube and the volume of power amplifier; This method will be restricted; And this method can only realize the vector adjustment in the two-dimensional space, and it utilizes sampling resistor to carry out current sample simultaneously, when supply power voltage is higher, isolates a little less than the effect; Fail safe is not high, and anti-interference is also not strong.

Simultaneously above-mentioned several patents is not all considered the influence that cause magnetic bearing voltage in the PWM dead band, and when Dead Time is bigger, when modulation frequency ratio is higher, the voltage difference accumulation that cause in the dead band will can not be ignored.

Summary of the invention

Technology of the present invention is dealt with problems: overcome the deficiency that prior art exists; A kind of magnetic bearing system switch power amplifier based on three-dimensional space vectors is provided, adopts modulation system, reduced the quantity of power tube and the volume of power amplifier based on three-dimensional space vectors; Reduced the amplitude of ripple; Reduced the loss of magnetic bearing system, it is fast to have response speed simultaneously, the programming flexible characteristic; Adopt the method for PWM dead band real-Time Compensation to improve control precision; Employing current with high accuracy instrument transformer is as the current feedback testing circuit, and control electricity (light current) and power electricity (forceful electric power) isolation effect are good, safe, and accuracy of detection is high, and strong interference immunity, responsive bandwidth height are easy to realize.

Technical solution of the present invention: a kind of magnetic bearing system switch power amplifier based on three-dimensional space vectors; Mainly comprise controller, isolated drive circuit, four brachium pontis power main circuits, current feedback testing circuit, signal conditioning circuit, signal filter circuit, wherein:

Controller: the displacement signal of displacement transducer and the current feedback signal of three coils of magnetic bearing are sampled through inner AD translation interface; It is poor that displacement signal that utilization collects and magnetic bearing rotor reference bit shifting signal are done, and the magnetic bearing position error signal is calculated according to control algolithm, generates the electric current expected signal value; It is poor that electric current expected signal value and current feedback signal value are done; Obtain error size, utilize dead area compensation algorithm computation PWM Dead Time to accumulate magnetic bearing coil voltage rising value or the drop-out value that causes simultaneously, and convert this rising value or drop-out value to the electric current correction value; With this electric current correction value the error signal that obtains is revised; Utilize the space vector algorithm to carry out the PWM modulation to the error signal after revising, output eight-path PWM signal (PWM1～PWM8), deliver to isolated drive circuit;

Isolated drive circuit: input links to each other with the pwm signal of controller output, and output is joined with four brachium pontis power main circuits, is used for generating the gate drive signal of four brachium pontis power main circuit power switch pipes;

Four brachium pontis power main circuits: control the conducting and the shutoff of eight power switch pipes of upper and lower brachium pontis by the gate drive signal of isolated drive circuit output, thereby in three coils of magnetic bearing, generate the proportional electric current output of the expectation Current Control amount of calculating with controller;

Three current feedback testing circuits: input is joined with four brachium pontis power main circuits, and output is joined with modulate circuit, is respectively applied for three coil current feedback signals of the magnetic bearing that detects four brachium pontis power main circuits;

Signal conditioning circuit: output is joined with signal filter circuit, is used for the current feedback signal of three current feedback testing circuit outputs is carried out level deviation, zooms in or out;

Signal filter circuit: input is connected with signal conditioning circuit conditioning signal afterwards; The noise signal that is used for the filtering input signal; The AD translation interface of output and controller joins; Under the control of master controller DSP, three current feedback signals of signal filter circuit output are sampled.

Described controller is made up of DSP and FPGA; Wherein DSP is as master controller; Main completion magnetic bearing rotor-position signal control algolithm, dead area compensation algorithm and the three-dimensional space vectors algorithm be responsible for, FPGA is as the peripheral interface chip of DSP, as pilot controller; Mainly be used for receiving the order of DSP, the pwm signal that generation needs.DSP applying three-dimensional means of space vector representation calculates the ON time of four power switch pipe expectations of brachium pontis on the four brachium pontis main circuits; And utilize this ON time to calculate conducting and trigger constantly and turn-off and trigger constantly; And will turn-off to trigger constantly and deliver to FPGA with generating pwm signal as corresponding comparison value; The FPGA generation cycle is the triangular carrier counting of T; Accept four comparison values that DSP sends here simultaneously and compare the pwm signal PWM1～PWM4 that obtains four power switch pipes of brachium pontis with the triangular carrier count value respectively, the signal PWM5～PWM8 of four power switch pipes of following brachium pontis is obtained after dead band logic that FPGA produces and inverted logic by PWM1～PWM4.

Described dead area compensation algorithm steps is:

1. the rated current positive direction is calculated the voltage difference △ U before and after the each point compensation according to the sense of current of 4 of A, B, C, D from left to right _A, △ U _B, △ U _C, △ U _D, the amplitude of each point voltage offset is △ U=N * T _{Dead_time}* T/U, wherein N represent one modulation period intercarrier number, reduce T along with the increase of rotating speed _{Dead_time}Represent Dead Time, the amplitude of U representative power supply direct voltage, T represents carrier cycle.

2. the electric current that flows through 4 of A, B, C, D is respectively I ₁, I ₂-I ₁, I ₃-I ₂,-I ₃, when the sense of current that flows through 4 of A, B, C, D is correct time, voltage compensation value is being for just, when the sense of current when negative, voltage compensation value is for negative.So the voltage compensation value that A, B, C, D are 4 is respectively sign (I ₁) * △ U, sign (I ₂-I ₁) * △ U, sign (I ₃-I ₂) * △ U, sign (I ₃) * △ U, wherein I ₁, I ₂, I ₃The electric current of coil 1, coil 2, coil 3 is flow through in representative respectively, and sign representes sign function.

3. the voltage compensation value that calculates three coils according to the voltage compensation value of each point is respectively: △ U ₁=△ U _A-△ U _B, △ U ₂=△ U _B-△ U _C, △ U ₃=△ U _C-△ U _D, △ U ₁, △ U ₂, △ U ₃Represent the voltage compensation value of three coils respectively, and convert three voltage compensation values the electric current correction value △ I of three coils to respectively divided by coil resistance ₁, △ I ₂, △ I ₃

Described three-dimensional space vectors algorithm steps is:

1. master controller DSP calculates in real time and utilizes the dead area compensation algorithm to carry out the dead band and revise the correcting current error amount that obtains three coils of magnetic bearing;

2. utilize three correcting current error amounts to carry out the voltage-regulation amount that the PID computing obtains the three-dimensional space vectors expectation;

3. DSP confirms the residing interval of output voltage vector according to the size and Orientation of the voltage-regulation amount of the three-dimensional space vectors expectation that obtains;

4. calculate the ON time that four power tubes of brachium pontis are expected on the four brachium pontis main circuits according to residing interval, and then calculate the conducting triggering moment and the shutoff triggering moment of power switch pipe;

5. four that will obtain are turn-offed triggering and send into pilot controller FPGA constantly; Compare with the triangular carrier count value of FPGA and to obtain brachium pontis four road pwm signals; Simultaneously last brachium pontis four road pwm signals are added inverted logic and dead band logic, obtain down brachium pontis four road pwm signals;

Control principle of the present invention: as far as power amplifier of magnetic bearing switch; Through conducting and the shutoff of eight power switch pipe VT1～VT8 on four brachium pontis are controlled; Can control the conducting and the shutoff of coil 1, coil 2 and the coil 3 of magnetic bearing simultaneously; Straight-through for fear of the power switch pipe up and down of same brachium pontis simultaneously; Necessarily require the four brachium pontis signal inversion that up and down power switch pipe is corresponding and add the dead band time-delay, be i.e. the corresponding signal of VT1～VT8: S1 and S5, S2 and S6, S3 and S7, S4 and S8 anti-phase and have the dead band and delay time.Like Fig. 3 and shown in Figure 5, wherein the dashed region of Fig. 5 arrow indication is represented the dead band, and Dead Time was confirmed according to the service time and the turn-off time of device; H and L represent respectively any brachium pontis in the four brachium pontis power main circuits two switching tubes do not add the dead band up and down the time pwm signal, H1 and L1 represent respectively any brachium pontis in the four brachium pontis power main circuits two switching tubes add dead bands up and down the time pwm signal.Get different logical value (0 or 1) through controlling four power switch pipe gate drive signals of brachium pontis (S1S2S3S4); Can be combined into 16 kinds of states; Comprising 14 non-zero basic vectors and two these vectors of zero-base, the space voltage vector that each on off state is corresponding is synthetic by same interval three coil voltage vectors.Its spatial distribution is as shown in Figure 6.Owing to adopt four brachium pontis structures; So the zone of whole voltage vector is divided into the individual interval of 24 (4 factorials); The division principle in 24 intervals is definite successively according to the principle that guarantees switching tube participation conducting minimum in adjacent twice handoff procedure and shutoff according to 16 basic vectors; Promptly have only a half-bridge to participate in conducting and shutoff in four brachium pontis, promptly produce minimum switching loss; Minimum for the space vector harmonic wave that makes generation simultaneously; Each road voltage vector adopts the symmetrical expression distributed architecture in each switch periods; Each switch periods is divided into five parts; Three ON times that part is three non-zero basic voltage vectors wherein are if this three part-times sum less than switch periods, is then given two these vectors of zero-base with this difference mean allocation.Adopt nine section space vector algorithms of symmetry; Beginning and ending phase in each switch periods are the action time of two these vectors of zero-base; Other three non-zero basic voltage vectors will be divided into the left and right sides that two parts are distributed in this vector of zero-base symmetrically, promptly according to nine segmentation sequential action shown in this vector of this vector of this vector of zero-base 1 → non-zero basic vector 1 → non-zero basic vector 2 → non-zero basic vector 3 → zero-base 2 → non-zero basic vector 3 → non-zero basic vector 2 → non-zero basic vector 1 → zero-base 1.Each interval corresponding basic voltage vectors, basic voltage vectors sequence of operation and each interval Rule of judgment are as shown in table 1.Ux, Uy, Uz represent the reference voltage regulated quantity of three coil expectations in the three-dimensional space vectors, Vi (i=0,1,2 respectively in the table 1 ... 15) represent 16 basic vectors respectively.The division principle in 24 intervals is definite successively according to the principle that guarantees switching tube participation conducting minimum in adjacent twice handoff procedure and shutoff according to 16 basic vectors.Ti (i=0,1,2 ... 15) represent action time of 16 basic vectors respectively; T represents carrier cycle, and U is the amplitude of power supply direct voltage, the Rule of judgment in affiliated interval according to the ON time of each basis vector in interval more than or equal to zero; Dropping on the 5th interval with reference voltage vector Vref is that example describes: this interval basic voltage vectors is V14, V6 and V4; Its basic role time is respectively T14, T6 and T4, promptly (S1 S2 S3 S4) to get the time of (1110) be T14, promptly three coil voltages are (00U) time is T14; The time that (S1 S2 S3 S4) gets (0110) is T6; Promptly three coil voltages are that (time U0U) is T6, and the time that (S1 S2 S3 S4) gets (0100) is T4, and promptly three coil voltages are that (time UU0) is T4; According to vector equivalent equation Vref * T=T14 * V14+T10 * V6+T8 * V4, can be converted into following equation group:

$\left\{\begin{array}{c}\mathrm{Ux}\&times;T=T14\&times;0+\mathrm{<figure-callout\; id="6"\; label="T"\; filenames="HDA00001999181900021.png,HDA00001999181900052.png"\; state="\{\{state\}\}">T</figure-callout>}6\&times;(-U)+T4\&times;(-U)\\ \mathrm{Uy}\&times;T=T14\&times;0+\mathrm{<figure-callout\; id="6"\; label="T"\; filenames="HDA00001999181900021.png,HDA00001999181900052.png"\; state="\{\{state\}\}">T</figure-callout>}6\&times;0+T4\&times;U\\ \mathrm{Uz}\&times;T=T14\&times;U+\mathrm{<figure-callout\; id="6"\; label="T"\; filenames="HDA00001999181900021.png,HDA00001999181900052.png"\; state="\{\{state\}\}">T</figure-callout>}6\&times;U+T4\&times;0\end{array}\right.$

Solve an equation and organize:

$\left\{\begin{array}{c}T14=(\mathrm{Ux}+\mathrm{Uy}+\mathrm{Uz})\&times;T/\mathrm{<figure-callout\; id="6"\; label="U\; T"\; filenames="HDA00001999181900021.png,HDA00001999181900052.png"\; state="\{\{state\}\}">U</figure-callout>}& \\ T6=-(\mathrm{Ux}+\mathrm{Uy})\&times;T/U\\ T4=\mathrm{Uy}\&times;T/U\end{array}\right.$

Obtain reference voltage vector Vref according to T14 >=0, T6 >=0 and T4 >=0 and drop on the 5th interval judgement condition when interval:

$\left\{\begin{array}{c}\mathrm{Uy}\&GreaterEqual;0\\ \mathrm{Ux}+\mathrm{Uy}\&le;0\\ \mathrm{Ux}+\mathrm{Uy}+\mathrm{Uz}\&GreaterEqual;0\end{array}\right.$

Rule of judgment interval under in the of other 23 can similarly obtain successively.

Interval voltage sequence of operation of table 1 and interval judgement condition

According to the affiliated interval division condition shown in the table 1, judge that expectation voltage-regulation amount Vref (Ux Uy Uz) is affiliated interval, calculate the action time of each basic voltage vectors then according to interval basic voltage vectors sequence of operation.For example: if expectation voltage-regulation amount Vref (Ux Uy Uz), the Ux+Uy that satisfies condition>=0, Uy≤0; Uy+Uz>=0 then can know that according to last table reference voltage vector Vref drops on the 3rd interval, according to the minimum principle of the minimum harmonic of switching loss; This interval basic voltage vectors can be known by table 1 should be taken as (V14, V10, V8); Then can to pass through basic vector (V14, V10, V8) effect synthetic for the action effect of Vref, that is: Vref * T=T14 * V14+T10 * V10+T8 * V8, and wherein be T14 the action time of V14; Be T10 the action time of V10, and be T8 the action time of V8.Vi (i=0,1,2 wherein ... 15) represent 16 basic vectors respectively, Ti (i=0,1,2 ... 15) represent action time of 16 basic vectors respectively, T represents carrier cycle.Because the present invention adopts nine section space vector algorithms of symmetry,, be half the action time of zero vector V15: 1/2 * T15=t in the beginning and the ending phase of each switch periods ₀/ 4, and the interlude section of switch periods is 0 action time of this vector V of zero-base: T0=t ₀/ 2.T wherein ₀Be sum action time of this vector of zero-base (V0 and V15), other three non-zero basic voltage vectors will be divided into the left and right sides that two parts are distributed in this vector V of zero-base 15 symmetrically.As shown in Figure 7, the time that (S1 S2 S3 S4) gets (1110) is T14, and promptly three coil voltages are (00U) time is T14; The time that (S1 S2 S3 S4) gets (1010) is T10; Promptly three coil voltages are (U-UU) time is T10, and the time that (S1 S2 S3 S4) gets (1000) is T8, and promptly three coil voltages are (U00) time is T8; The time that (S1 S2 S3 S4) gets (0000) is T0; Promptly three coil voltages are (000) time is T0, and the time that (S1 S2 S3 S4) gets (1111) is T15, and promptly three coil voltages are (000) time is T15.Wherein U is the amplitude of power supply direct voltage.Vector equivalent equation Vref * T=T14 * V14+T10 * V10+T8 * V8 can be converted into following equation group:

$\left\{\begin{array}{c}\mathrm{Ux}\&times;T=T14\&times;0+\mathrm{<figure-callout\; id="10"\; label="T"\; filenames="HDA00001999181900052.png"\; state="\{\{state\}\}">T</figure-callout>}10\&times;U+T8\&times;U\mathrm{}\\ \mathrm{Uy}\&times;T=T14\&times;0+\mathrm{<figure-callout\; id="10"\; label="T"\; filenames="HDA00001999181900052.png"\; state="\{\{state\}\}">T</figure-callout>}10\&times;(-U)+T8\&times;0\\ \mathrm{Uz}\&times;T=T14\&times;U+\mathrm{<figure-callout\; id="10"\; label="T"\; filenames="HDA00001999181900052.png"\; state="\{\{state\}\}">T</figure-callout>}10\&times;U+T8\&times;0\end{array}\right.$

Can obtain through the solving equation group:

$\left\{\begin{array}{c}T14=(\mathrm{Uy}\&times;T+\mathrm{Uz}\&times;T)/\mathrm{<figure-callout\; id="10"\; label="U\; T"\; filenames="HDA00001999181900052.png"\; state="\{\{state\}\}">U</figure-callout>}& \\ T10=-\mathrm{Uy}\&times;T/U\\ T8=(\mathrm{Ux}\&times;T+\mathrm{Uy}\&times;T)/U\end{array}\right.$

Thereby can obtain T15=T0=action time (T-T14-T10-T8)/2 of two zero vectors, so the high level width of S1 signal is: T15+T14+T10+T8=t ₀/ 2+t ₁+ t ₂+ t ₃The high level width of S2 signal is: T15+T14=t ₀/ 2+t ₁The high level width of S3 signal is: T15+T14+T10=t ₀/ 2+t ₁+ t ₂The high level width of S4 signal is: T15=t ₀/ 2; T wherein ₀Be sum action time of this vector of zero-base (V0 and V15), t ₁, t ₂And t ₃Be respectively three corresponding non-zero basic vectors of Vref according to conducting order action time successively, promptly for this routine t ₁=T14, t ₂=T10, t ₃=T8, t ₀=T-T14-T10-T8, t ₁, t ₂And t ₃Size by the decision of the size and Orientation of Vref, can obtain the ON time of each power switch pipe according to the high level width of the corresponding triggering signal of four power switch pipes of last brachium pontis; Utilize the ON time combination symmetry of each power switch pipe can calculate the conducting triggering moment and turn-off the triggering moment; Owing to adopt the symmetry structure among the present invention; Trigger constantly so only need obtain the shutoff of four switching tubes of brachium pontis, promptly level is by the moment of high step-down, in this example: t _{Trig_off_1}=t ₀/ 4+t ₁/ 2+t ₂/ 2+t ₃/ 2, t _{Trig_off_2}=t ₀/ 4+t ₁/ 2, t _{Trig_off_3}=t ₀/ 4+t ₁/ 2+t ₂/ 2, t _{Trig_off_4}=t ₀/ 4, t wherein _{Trig_off_1}, t _{Trig_off_2}, t _{Trig_off_3}, t _{Trig_off_4}Corresponding respectively shutoff of going up four power switch pipes of brachium pontis triggers constantly, and other interval space vectors that in like manner can obtain under other states are realized, and then realized the control to the magnetic bearing coil current.Other interval ON times are constantly as shown in table 2 with the shutoff triggering, and the X in the table 2, Y, Z represent Ux, Uy, Uz respectively, and T represents carrier cycle, and U is the amplitude of power supply direct voltage.

Each interval ON time of table 2 triggers timetable with turn-offing

The present invention realizes with existing analogue device or the magnetic bearing of Digital Implementation is compared with switch power amplifier, and advantage is:

(1) the control permanent magnet biased magnetic bearing need be controlled five degrees of freedom usually; Need two radial direction magnetic bearings of control and axial magnetic bearing totally five road magnetic bearing coils; The present invention is through adopting the topological structure of three-dimensional space vectors control technology and four brachium pontis power main circuits; Utilize eight power tubes independently to control three independently coil currents; The power tube that the magnetic bearing system of 5 coils of control is needed is reduced to 14 by 20, and (one four brachium pontis power main circuit is controlled a radial direction magnetic bearing x, y direction and axial magnetic bearing direction totally three coils respectively, needs 8 power tubes; One three brachium pontis power main circuit is controlled the two-way coil of another radial direction magnetic bearing x, y direction; Need 6 power tubes, totally 14 power tubes), reduced power tube quantity and power amplifier volume; Improve integrated level, reduced the amplitude of ripple and the loss of magnetic bearing system.

(2) the present invention adopts the combination of high speed digital signal processor DSP and FPGA to carry out the three-dimensional space vectors modulation; With DSP as master controller; Give full play to the advantage that its computing capability is strong and peripheral interface is abundant, have system responses fast, FPGA is as pilot controller; The double peripheral expansion of being DSP is given full play to its advantage flexibly of programming.

(3) the present invention adopts PWM dead band real-Time Compensation, calculates the voltage compensation value △ U of each point according to the sense of current of 4 of A, B, C, D _A, △ U _B, △ U _C, △ U _DWherein flow through the electric current that electric current that A orders equals to flow through coil 1; Flow through the electric current that electric current that electric current that B orders equals coil 2 deducts coil 1, flow through the electric current that electric current that C orders equals to flow through coil 3 and deduct the electric current that flows through coil 2, flow through the opposite number that electric current that D orders equals to flow through the electric current of coil 3.Obtaining the voltage compensation value that the correspondent voltage compensation value calculation goes out three coils according to the electric current of each point is respectively: △ U ₁=△ U _A-△ U _B, △ U ₂=△ U _B-△ U _C, △ U ₃=△ U _C-△ U _D, △ U ₁, △ U ₂, △ U ₃Represent the voltage compensation value of three coils respectively, three voltage compensation values are converted to the electric current correction value △ I of three coils respectively divided by coil resistance ₁, △ I ₂, △ I ₃Bigger when the supply power voltage of the coil of magnetic bearing, when Dead Time is bigger, the dead band voltage influence is bigger, through real-time dead area compensation, can reach the purpose that improves control precision.

Description of drawings

Fig. 1 is existing unicoil full bridge power main circuit diagram

Fig. 2 is existing three brachium pontis power main circuit diagrams;

Fig. 3 is a hardware composition frame chart of the present invention;

Fig. 4 is that controller of the present invention is formed and flow chart;

The schematic diagram that Fig. 5 produces and adds the dead band for pwm signal;

Fig. 6 is the basic vector figure of three-dimensional space vectors algorithm of the present invention;

Fig. 7 is the equivalent exploded view of the 3rd interval vector in the three-dimensional space vectors algorithm of the present invention;

Fig. 8 is a three-dimensional space vectors algorithm flow chart of the present invention;

Fig. 9 is a current feedback testing circuit of the present invention;

Figure 10 is signal conditioning circuit of the present invention and signal filter circuit circuit.

Embodiment

As shown in Figure 3; The present invention mainly comprises: controller, isolated drive circuit, four brachium pontis power main circuits, current feedback testing circuit, signal conditioning circuit, signal filter circuit; Wherein: controller is sampled to the displacement signal of displacement transducer and the current feedback signal of three coils of magnetic bearing through inner AD translation interface; It is poor that displacement signal that utilization collects and magnetic bearing rotor reference bit shifting signal are done, and the magnetic bearing position error signal is calculated according to control algolithm, generates the electric current expected signal value; It is poor that electric current expected signal value and current feedback signal value are done; Obtain error size, utilize dead area compensation algorithm computation PWM Dead Time to accumulate magnetic bearing coil voltage rising value or the drop-out value that causes simultaneously, and convert this rising value or drop-out value to the electric current correction value; With this electric current correction value the error signal that obtains is revised; Utilize the space vector algorithm to carry out the PWM modulation to the error signal after revising, output eight-path PWM signal (PWM1～PWM8), deliver to isolated drive circuit; The input of isolated drive circuit links to each other with the PWM1～PWM8 signal of controller output, exports gate drive signal S1～S8 of power switch pipe VT1～VT8 in the four brachium pontis power main circuits, directly links to each other with the grid of four brachium pontis power main circuit switch pipes; Four brachium pontis power main circuits are exported thereby in three coils of magnetic bearing, generate with the proportional electric current of Current Control amount by conducting and the shutoff of brachium pontis in the gate drive signal S1～S8 control of isolated drive circuit output and eight power switch pipe VT1～VT8 of following brachium pontis; The input of current feedback testing circuit directly is in series with four brachium pontis power main circuits, and output connects signal conditioning circuit, is used to detect three coil current feedback signals of the magnetic bearing of four brachium pontis power main circuits; Modulate circuit and signal filter circuit join, and are used for the current feedback signal of three current feedback testing circuit outputs is carried out level deviation, zooms in or out; Signal filter circuit is connected with signal conditioning circuit conditioning signal afterwards, is used for the noise signal of filtering input signal, and three current feedback signals of output are connected to the AD conversion mouth of controller and gather.

Controller comprises master controller DSP and pilot controller FPGA.Master controller DSP utilizes built-in AD translation interface that the displacement signal of displacement transducer and the current feedback signal of three coils of magnetic bearing are sampled; It is poor that displacement signal that utilization collects and magnetic bearing rotor reference bit shifting signal are done; The magnetic bearing position error signal is calculated according to control algolithm; Generate the electric current expected signal value; And this electric current desired value and current feedback value are done difference obtain three current error signals, DSP adopts magnetic bearing coil voltage rising value or the drop-out value that the accumulation of dead area compensation algorithm computation PWM Dead Time causes then, and converts this rising value or drop-out value to the electric current correction value; With this electric current correction value three current error signals are revised, utilized three corrections error afterwards to carry out the voltage-regulation amount that the PID computing obtains the three-dimensional space vectors expectation.DSP is according to the size and Orientation of the voltage-regulation amount of the three-dimensional space vectors expectation that obtains; Generate four road comparison values according to the three-dimensional space vectors algorithm; The count value of four road comparison values and triangular carrier is compared; Obtain the PWM1～PWM4 signal of four power switch pipes of brachium pontis, simultaneously four road pwm signals are added inverted logic and dead band logic, obtain down the PWM5～PWM8 signal of four pipes of brachium pontis; Generate the gate drive signal of the power switch pipe of four brachium pontis power amplifier main circuits 3: S1～S8 through isolated drive circuit 2; Wherein S1 and S5, S2 and S6, S3 and S7, S4 and S8 anti-phase and add the dead band respectively; Conducting and shutoff by S1～eight power switch pipes of S8 control; Current feedback testing circuit 4 obtains the current feedback signal of coil through the current value of magnetic bearing coil in the isolation detection four brachium pontis power main circuits 3.

Wherein VT1 and VT5 constitute first brachium pontis; VT2 and VT6 constitute second brachium pontis; VT3 and VT7 constitute the 3rd brachium pontis; VT4 and VT8 constitute the 4th brachium pontis, and magnetic bearing coil 1 is connected between first brachium pontis and second brachium pontis, and the coil two-end-point is respectively A and B, and the coil voltage is U _ABMagnetic bearing coil 2 is connected between second brachium pontis and the 3rd brachium pontis, and the coil two-end-point is respectively B and C, and the coil voltage is U _BCMagnetic bearing coil 3 is connected between the 3rd brachium pontis and the 4th brachium pontis, and the coil two-end-point is respectively C and D, and the coil voltage is U _CDPromptly second brachium pontis and the 3rd brachium pontis are the public brachium pontis of two magnetic bearing coils; 2 of B and C are two public tie points of magnetic bearing coil, and the drive signal of last brachium pontis power switch pipe (S1, S2, S3, S4) is respectively with drive signal (S5, S6, S7, the S8) anti-phase of following brachium pontis power switch pipe and to add the dead band logic straight-through to prevent upper and lower bridge arm.The high precision electric current transducer of contacting respectively in magnetic bearing coil 1, magnetic bearing coil 2 and the magnetic bearing coil 3 will be controlled electricity (light current) effectively and isolate with power electricity (forceful electric power), the electric current of while magnetic test coil.

As shown in Figure 4, controller of the present invention is made up of master controller DSP and pilot controller FPGA.DSP mainly is responsible for accomplishing magnetic bearing rotor-position signal control algolithm, dead area compensation algorithm and three-dimensional space vectors algorithm as master controller; FPGA as pilot controller, mainly is used for receiving the order of DSP as the peripheral interface chip of DSP, the pwm signal that generation needs; DSP utilizes built-in AD interface to carry out feedback current sampling and displacement sampling; It is poor that the displacement signal of displacement signal that the DSP utilization collects and the expectation of magnetic bearing rotor is done; After the magnetic bearing position error signal carried out control algolithm; Generate the electric current desired value; DSP obtains three current error values after this expectation current value is done difference with the sampled value of current feedback signal before, and DSP utilizes magnetic bearing coil voltage rising value or the drop-out value that the accumulation of dead area compensation algorithm computation PWM Dead Time causes then, and converts this rising value or drop-out value to the electric current correction value; With this electric current correction value three current error signals are revised, utilized three corrections error afterwards to carry out the voltage-regulation amount that the PID computing obtains the three-dimensional space vectors expectation.DSP is according to the voltage-regulation amount size and Orientation of the three-dimensional space vectors expectation that obtains; The applying three-dimensional means of space vector representation calculates the ON time of four power switch pipe expectations of brachium pontis on the four bridge main circuits; And utilize this ON time to calculate conducting and trigger constantly and turn-off and trigger constantly; And will turn-off to trigger constantly and deliver to FPGA with generating pwm signal as corresponding comparison value; The FPGA generation cycle is the triangular carrier counting of T, accepts four comparison values that DSP sends here simultaneously and compares with the triangular carrier count value respectively, if the comparison value of sending here carries count value greater than the triangle that generates; Then export high level; Otherwise output low level then obtains the pwm signal PWM1～PWM4 of four power switch pipes of brachium pontis thus, and the signal PWM5～PWM8 of four power switch pipes of following brachium pontis is obtained after dead band logic that FPGA produces and inverted logic by PWM1～PWM4.

As shown in Figure 5, the PWM formation logic when not adding the dead band is: the comparison value of sending here as DSP is during greater than the triangular carrier count value, and last brachium pontis pwm signal is a high level, and following brachium pontis pwm signal is a low level; The comparison value of sending here as DSP is during less than the triangular carrier count value, and last brachium pontis pwm signal is a low level, and following brachium pontis pwm signal is a high level; Open simultaneously for two power tubes up and down that prevent same brachium pontis and to cause short circuit; Must add the dead band logic; The pwm signal of promptly going up the brachium pontis power switch pipe is not adding time-delay a period of time conducting on the basis in dead band, is turn-offing on time, and following brachium pontis power switch pipe is not adding a period of time conducting of turn-offing on time, delay time on the basis in dead band.The change in voltage that the interpolation dead band causes will utilize the dead area compensation algorithm to revise, and the dead area compensation algorithm steps is:

1. the rated current positive direction is calculated the voltage difference △ U before and after the each point compensation according to the sense of current of 4 of A, B, C, D from left to right _A, △ U _B, △ U _C, △ U _D, the amplitude of each point voltage offset is △ U=N * T _{Dead_time}* T/U, wherein N represent one modulation period intercarrier number, reduce T along with the increase of rotating speed _{Dead_time}Represent Dead Time, the amplitude of U representative power supply direct voltage, T represents carrier cycle.

2. the electric current that flows through 4 of A, B, C, D is respectively I ₁, I ₂-I ₁, I ₃-I ₂,-I ₃, when the sense of current that flows through 4 of A, B, C, D is correct time, voltage compensation value is being for just, when the sense of current when negative, voltage compensation value is for negative.So the voltage compensation value that A, B, C, D are 4 is respectively sign (I ₁) * △ U, sign (I ₂-I ₁) * △ U, sign (I ₃-I ₂) * △ U, sign (I ₃) * △ U, wherein I ₁, I ₂, I ₃The electric current of coil 1, coil 2, coil 3 is flow through in representative respectively, and sign representes sign function.

3. the voltage compensation value that calculates three coils according to the voltage compensation value of each point is respectively: △ U ₁=△ U _A-△ U _B, △ U ₂=△ U _B-△ U _C, △ U ₃=△ U _C-△ U _D, △ U ₁, △ U ₂, △ U ₃Represent the voltage compensation value of three coils respectively, and convert three voltage compensation values the electric current correction value △ I of three coils to respectively divided by coil resistance ₁, △ I ₂, △ I ₃

As shown in Figure 6, according to the state of S1, S2, S3 and S4 (S1 and S5, S2 and S6, S3 and S7, S4 and S8 add respectively dead band after anti-phase), four brachium pontis can be combined into 16 kinds of on off states, comprising two zero vectors and 14 non-zero vectors.The voltage U on the magnetic bearing coil that is connected between brachium pontis mid point A, B _ABThe voltage of being used as the X axle on an end magnetic bearing XY plane is the voltage U on the magnetic bearing coil that is connected between brachium pontis mid point B, the C _BCThe voltage of being used as the Y axle on an end magnetic bearing XY plane is the voltage U on the magnetic bearing coil that is connected between brachium pontis mid point C, the D _CDBe used as axial voltage, i.e. the voltage of Z axle.16 kinds of on off states (0000), (0001) ..., (1111) respectively corresponding 16 basic voltage vectors V0 of output, V1 ..., V15.Wherein V0 and V15 are two these voltage vectors of zero-base, respectively corresponding 14 the non-zero basic voltage vectors of V1～V14, and these 16 basic voltage vectors are divided into 24 intervals to three dimensions XYZ.16 kinds of conducting states of three coils of 16 kinds of corresponding magnetic bearings of fundamental space vector.The space voltage vector that each on off state is corresponding is synthetic by each three interval non-zero basic voltage vectors.

Adopt three-dimensional space vectors algorithm controls four brachium pontis power amplifier main circuits; Charging, discharge and three kinds of different state of free afterflow can appear in three coils of magnetic bearing in the course of the work, and these characteristics make four brachium pontis power amplifier main circuits of three-dimensional space vectors algorithm controls have the advantage that ripple is little, loss is little that three level control methods are had.But the present invention is when possessing above-mentioned advantage, and the 3rd brachium pontis that second brachium pontis and VT3 and the VT7 formed that VT2 and VT6 formed is shared by two magnetic bearing coil institutes, and switching loss also reduces greatly when having reduced power switch pipe quantity.

The present invention adopts nine section space vector pulse width modulation modes of symmetry; Each basic vector is divided into nine sections in each switch periods; Beginning and ending phase in each switch periods; Be zero vector V15 action time, and the interlude section of switch periods is 0 action time of this vector V of zero-base, zero vector V15 and V0 divide the ON time of zero vector equally; Other three non-zero basic voltage vectors will be divided into the left and right sides that two parts are distributed in this vector V of zero-base 0 symmetrically; Whole like this periodic symmetry is divided into nine sections, and sequence of operation and the time of each basic vector in each switch periods is symmetrically distributed, and each the road pulse-width signal that is produced also is symmetrical.t ₀Be sum action time of this vector of zero-base (V0 and V15), t ₁, t ₂And t ₃Be respectively interval three non-zero basic vectors of living in according to conducting order action time successively.In the beginning and the ending phase of each switch periods, be the action time of zero vector V15: t ₀/ 4, and the interlude section of switch periods is zero vector V0 action time: t ₀/ 2; Other three non-zero basic voltage vectors will be divided into the left and right sides that two parts are distributed in zero vector V0 symmetrically; The selection principle of the sequence of operation of basic voltage vectors guarantees that the conversion of each on off state all has only one to change, promptly when eight power switch pipes when a kind of on off state is transformed into another kind of on off state, have only a brachium pontis to participate in the change of current; So not only the switch number of times can be reduced, and switching loss can be reduced.

As shown in Figure 8, the software realization flow of three-dimensional space vectors algorithm of the present invention.Described three-dimensional space vectors algorithm steps is:

1. master controller DSP calculates in real time and utilizes the dead area compensation algorithm to carry out the dead band and revise the correcting current error amount that obtains three coils of magnetic bearing;

2. utilize three correcting current error amounts to carry out the voltage-regulation amount that the PID computing obtains the three-dimensional space vectors expectation;

3. DSP confirms the residing interval of output voltage vector according to the size and Orientation of the voltage-regulation amount of the three-dimensional space vectors expectation that obtains;

4. calculate the ON time that four power tubes of brachium pontis are expected on the four brachium pontis main circuits according to residing interval, and then calculate the conducting triggering moment and the shutoff triggering moment of power switch pipe;

5. four that will obtain are turn-offed triggering and send into pilot controller FPGA constantly; Compare with the triangular carrier count value of FPGA and to obtain brachium pontis four road pwm signals; Simultaneously last brachium pontis four road pwm signals are added inverted logic and dead band logic, obtain down brachium pontis four road pwm signals.

In the course of work of magnetic bearing; In the three-dimensional space vectors algorithm in each interval the switching signal of the sequence of operation of basic voltage vectors and power switch pipe become corresponding corresponding relation, so at first will calculate the current error signal of three coils of magnetic bearing in the middle of the working control; Dead Time according to the pwm signal design carries out the dead band correction to three current error signals then, utilizes the error after revising to carry out the voltage-regulation amount that the PID computing obtains the three-dimensional space vectors expectation, is positioned at which interval according to table 1 judgement voltage vector; Obtain t action time of three basic voltage vectors according to interval look-up table 2 of living in ₁, t ₂, t ₃, utilize formula t then ₀=T-t ₁-t ₂-t ₃Calculate t ₀, and then trigger t constantly according to the shutoff that table 2 obtains four power switch pipes _{Trig_off_1}, t _{Trig_off_2}, t _{Trig_off_3}, t _{Trig_off_4}The shutoff that obtains is triggered the moment deliver to FPGA as comparison value; Compare with the triangular carrier count value of FPGA; If the comparison value sent here carries count value greater than the triangle that generates, then export high level, on the contrary output low level then; Obtain the pwm signal PWM1～PWM4 of four power switch pipes of brachium pontis thus, the signal PWM5～PWM8 of four power switch pipes of following brachium pontis is obtained after dead band logic that FPGA produces and inverted logic by PWM1～PWM4.

The PWM carrier cycle that adopts among the present invention is 20kHz; The crystal oscillator of FPGA is 40MHz in this enforcement; Because the symmetrical PWM ripple is adopted in this enforcement, so the triangular carrier that adopts is the symmetric triangular ripple, so maximum triangular carrier count value is 40M/20K/2=1000; Direct voltage U correspondence 1000, the cycle T of symmetric triangular carrier wave corresponding 2000.Calculate three error signal question blanks 1 after DSP revises according to the dead band and judge interval of living in, obtain t action time of three non-zero basic vectors according to interval query table 2 of living in ₁, t ₂And t ₃, and then utilize formula t then ₀=T-t ₁-t ₂-t ₃Calculate t ₀, according to t ₀, t ₁, t ₂And t ₃The turn-off time of four switching tubes of brachium pontis in the calculating is for example to being positioned at the reference vector Vref in the 3rd interval, the t that calculates among Fig. 7 _{Trig_off_1}=t ₀/ 4+t ₃/ 2+t ₂/ 2+t ₁/ 2, t _{Trig_off_2}=t ₀/ 4+t ₁/ 2, t _{Trig_off_3}=t ₀/ 4+t ₁/ 2+t ₂/ 2, t _{Trig_off_4}=t ₀/ 4, t wherein _{Trig_off_1}, t _{Trig_off_2}, t _{Trig_off_3}, t _{Trig_off_4}Correspondence goes up the shutoff moment of four power switch pipes of brachium pontis respectively, above-mentioned four values is composed respectively to four comparison value CMP1, CMP2, CMP3 and CMP4 sent into the pwm signal that FPGA is used to produce needs.Below be the example explanation three-dimensional space vectors method course of work with an example in the actual implementation process: suppose that three current error values that after the correction of overcurrent dead band, obtain are respectively: Ux=300, Uy=-100 after the current signal collection of DSP with three coils of magnetic bearing; Uz=200; Since Ux+Uy>=0, Uy≤0, Uy+Uz>=0; Question blank 1 can know that this vector is positioned at the 3rd interval; Because T=2000, U=1000 can get according to interval query table 2 of living in: the time that (S1 S2 S3 S4) gets (1110) is t ₁=200, the time of getting (1010) is t ₂=200, the time of getting (1000) is t ₃=400, remaining time t ₀=2000-200-200-400=1200 mean allocation is given V15 and V0.According to t ₀, t ₁, t ₂And t ₃Can obtain t _{Trig_off_1}=t ₀/ 4+t ₁/ 2+t ₂/ 2+t ₃/ 2=700, t _{Trig_off_2}=t ₀/ 4+t ₁/ 2=400, t _{Trig_off_3}=t ₀/ 4+t ₁/ 2+t ₂/ 2=500, t _{Trig_off_4}=t ₀/ 4=300 triggers the moment as comparison value with the shutoff that obtains, i.e. CMP1=t _{Trig_off_1}=700, CMP2=t _{Trig_off_2}=400, CMP3=t _{Trig_off_3}=500, CMP4=t _{Trig_off_4}=300; And four comparison values are sent among the FPGA signal PWM1～PWM4 that relatively can obtain four power switch pipes of brachium pontis with triangular carrier, the signal PWM5～PWM8 of four power switch pipes of following brachium pontis obtains after adding dead band logic and inverted logic by PWM1～PWM4.

As shown in Figure 9, provided current feedback testing circuit of the present invention.I among Fig. 9+and I-represent electric current to flow into end and electric current outflow end respectively; With I+and I-be concatenated into respectively in the magnetic bearing coil of Fig. 3; I+wiring loop current flows into end, I-wiring loop current outflow end, "+" and "-" of each current sensor in the corresponding diagram 3 respectively.Current sensor adopts multrirange current sensor LA28-NP, and the range of selection is 5A, is about to its 2 pin and links to each other respectively with 10 pin, 3 pin and 9 pin, 4 pin and 8 pin, 5 pin and 7 pin; 1 pin and 6 pin are unsettled; Turn ratio is selected 5:1000, during full scale, and the current signal of secondary side output 25mA; External one 360 ohm resistance R 1 is converted into voltage output signal I _ COIL with current signal, and at the resistance two ends and the capacitor C 1 that connects a 0.01uf it is carried out simple filtering.Current sensor carries out electrical isolation with electric current primary side and secondary side, strong interference immunity, and fail safe is good, and its bandwidth reaches 150kHz, and accuracy of detection reaches ± and 0.5%, and be easy to realize.

Shown in figure 10, provided signal conditioning circuit of the present invention and signal filter circuit circuit.The output of the current feedback testing circuit shown in its input I _ COIL map interlinking 9, output connects the AD mouth of DSP.Because the voltage of current sensor output is of ac; The scope that can gather for the AD mouth that is translated into DSP; Promptly 0～3.3V need nurse one's health it, at first current sensor is exported signal and adds that bias voltage dwindles afterwards; The operational amplifier that adopts is TL084, and its inside comprises four operational amplifiers.BIAS_ I among Figure 10 is represented bias voltage value, and U1A, U1B, U1C represent three operational amplifiers among the TL084 respectively.Resistance R 1 is as current-limiting resistance, and resistance is selected 10k, and resistance R 2, R3, R5 carry out the adjusting of minification, and R2 and R3 resistance are selected 10k, and R5 adopts the slide rheostat of 0～20k.Signal after will nursing one's health then carries out filtering; Eliminate the aliasing in spectra and the interference of high-frequency noise of digital system, employing be a second-order low-pass filter, capacitor C 1, C2 selection be 0.01uf; Resistance R 6 is selected 3.3k with the R7 resistance, and the cut-off frequency of low pass is elected 3.1kHz as.In order to guarantee that the signal after the filtering is strict controlled in 0～3.3V scope, so before advancing the AD mouth of DSP, added two back-to-back 3.3V voltage-stabiliser tube Z1 and Z2, the output signal I _ TO_AD after the filtering is sent to the AD mouth of DSP and gathers.

The control permanent magnet biased magnetic bearing need be controlled five degrees of freedom usually; Need two radial direction magnetic bearings of control and axial magnetic bearing totally five road magnetic bearing coils; During working control; With x, y direction and the axial magnetic bearing of a radial direction magnetic bearing totally three coils, receive successively on the coil 1, coil 2, coil 3 of four brachium pontis power main circuits shown in Figure 3, adopt three-dimensional space vectors algorithm shown in the present to control; The two-way magnetic bearing coil of the x of another radial direction magnetic bearing, y direction is received on coil 1 in the three brachium pontis power main circuits shown in Figure 2, the coil 2 successively, adopted the disclosed general spatial vector operation of Chinese patent " 200710120705.7 ".

The present invention is a kind of magnetic bearing system switch power amplifier based on three-dimensional space vectors, and the switch power amplifier that can be used as general magnetic bearing system is applied to the magnetic bearings control of systems such as magnetic levitaion motor, magnetically levitated flywheel, magnetic suspension control torque gyroscope.

Claims (4)

1. magnetic bearing system switch power amplifier based on three-dimensional space vectors; It is characterized in that comprising: controller (1), isolated drive circuit (2), four brachium pontis power main circuits (3), current feedback testing circuit (4), signal conditioning circuit (5), signal filter circuit (6), wherein:

Controller (1): the displacement signal of displacement transducer and the current feedback signal of three coils of magnetic bearing are sampled through the inner AD translation interface of controller; It is poor that displacement signal that utilization collects and magnetic bearing rotor reference bit shifting signal are done; The magnetic bearing position error signal is calculated according to control algolithm; Generate the electric current expected signal value, it is poor that electric current expected signal value and current feedback signal value are done, and obtains error size; Magnetic bearing coil voltage rising value or the drop-out value of utilizing the accumulation of dead area compensation algorithm computation PWM Dead Time to cause simultaneously; And convert this rising value or drop-out value to the electric current correction value, and with this electric current correction value the error signal that obtains is revised, utilize the space vector algorithm to carry out the PWM modulation to the error signal after revising; Output eight-path PWM signal (PWM1～PWM8), deliver to isolated drive circuit (2);

Isolated drive circuit (2): input links to each other with the PWM1～PWM8 signal of controller (1) output, exports gate drive signal S1～S8 of power switch pipe VT1～VT8 in the four brachium pontis power main circuits (3);

Four brachium pontis power main circuits (3): adopt eight power switch pipes independently to control the topological structure of three coils, wherein VT1 and VT5 constitute first brachium pontis; VT2 and VT6 constitute second brachium pontis; VT3 and VT7 constitute the 3rd brachium pontis; VT4 and VT8 constitute the 4th brachium pontis, and magnetic bearing coil 1 is connected between first brachium pontis and second brachium pontis, and the coil two-end-point is respectively A and B, and the coil voltage is U _ABMagnetic bearing coil 2 is connected between second brachium pontis and the 3rd brachium pontis, and the coil two-end-point is respectively B and C, and the coil voltage is U _BCMagnetic bearing coil 3 is connected between the 3rd brachium pontis and the 4th brachium pontis, and the coil two-end-point is respectively C and D, and the coil voltage is U _CD, the drive signal of last brachium pontis power switch pipe (S1, S2, S3, S4) is respectively with drive signal (S5, S6, S7, the S8) anti-phase of following brachium pontis power switch pipe and to add the dead band logic straight-through to prevent upper and lower bridge arm;

Current feedback testing circuit (4): input connects four brachium pontis power main circuits (3), and output connects signal conditioning circuit (5), is used to detect three coil current feedback signals of the magnetic bearing of four brachium pontis power main circuits (3);

Modulate circuit (5): join with signal filter circuit (6), be used for the current feedback signal of three current feedback testing circuits (4) output is carried out level deviation, zooms in or out;

Signal filter circuit (6): be connected with the signal after signal conditioning circuit (5) conditioning, be used for the noise signal of filtering input signal, three current feedback signals of output are connected to the AD conversion mouth of controller (1) and gather.

2. a kind of magnetic bearing system switch power amplifier according to claim 1 based on three-dimensional space vectors; It is characterized in that: described controller (1) is made up of DSP and FPGA, and wherein DSP mainly is responsible for accomplishing magnetic bearing rotor-position signal control algolithm, dead area compensation algorithm and three-dimensional space vectors algorithm as master controller; FPGA is as the peripheral interface chip of DSP; As pilot controller, mainly be used for receiving the order of DSP, the pwm signal that generation needs.DSP utilizes dead area compensation algorithm and three-dimensional space vectors method to calculate the ON time of four power switch pipe expectations of brachium pontis on the four brachium pontis main circuits; And utilize this ON time to calculate conducting and trigger constantly and turn-off and trigger constantly; And will turn-off to trigger constantly and deliver to FPGA with generating pwm signal as corresponding comparison value; The FPGA generation cycle is the triangular carrier counting of T; Accept four comparison values that DSP sends here simultaneously and compare the pwm signal PWM1～PWM4 that obtains four power switch pipes of brachium pontis with the triangular carrier count value respectively, the signal PWM5～PWM8 of four power switch pipes of following brachium pontis is obtained after dead band logic that FPGA produces and inverted logic by PWM1～PWM4.

3. a kind of magnetic bearing system switch power amplifier according to claim 1 and 2 based on three-dimensional space vectors, it is characterized in that: described dead area compensation algorithm steps is:

1. the rated current positive direction is calculated the voltage difference △ U before and after the each point compensation according to the sense of current of 4 of A, B, C, D from left to right _A, △ U _B, △ U _C, △ U _D, the amplitude of each point voltage offset is △ U=N * T _{Dead_time}* T/U, wherein N represent one modulation period intercarrier number, reduce T along with the increase of rotating speed _{Dead_time}Represent Dead Time, the amplitude of U representative power supply direct voltage, T represents carrier cycle;

2. the electric current that flows through 4 of A, B, C, D is respectively I ₁, I ₂-I ₁, I ₃-I ₂,-I ₃, when the sense of current that flows through 4 of A, B, C, D is correct time, voltage compensation value is being for just, when the sense of current when negative, voltage compensation value is for negative.So the voltage compensation value that A, B, C, D are 4 is respectively sign (I ₁) * △ U, sign (I ₂-I ₁) * △ U, sign (I ₃-I ₂) * △ U, sign (I ₃) * △ U, wherein I ₁, I ₂, I ₃The electric current of coil 1, coil 2, coil 3 is flow through in representative respectively, and sign representes sign function;

3. the voltage compensation value that calculates three coils according to the voltage compensation value of each point is respectively: △ U ₁=△ U _A-△ U _B, △ U ₂=△ U _B-△ U _C, △ U ₃=△ U _C-△ U _D, △ U ₁, △ U ₂, △ U ₃Represent the voltage compensation value of three coils respectively, and convert three voltage compensation values the electric current correction value △ I of three coils to respectively divided by coil resistance ₁, △ I ₂, △ I ₃

4. a kind of magnetic bearing system switch power amplifier according to claim 1 and 2 based on three-dimensional space vectors, it is characterized in that: described three-dimensional space vectors algorithm steps is:

1. master controller DSP calculates in real time and utilizes the dead area compensation algorithm to carry out the dead band and revise the correcting current error amount that obtains three coils of magnetic bearing;

2. utilize three correcting current error amounts to carry out the voltage-regulation amount that the PID computing obtains the three-dimensional space vectors expectation;

3. DSP confirms the residing interval of output voltage vector according to the size and Orientation of the voltage-regulation amount of the three-dimensional space vectors expectation that obtains;

4. calculate the ON time that four power tubes of brachium pontis are expected on the four brachium pontis main circuits according to residing interval, and then calculate the conducting triggering moment and the shutoff triggering moment of power switch pipe;

5. four that will obtain are turn-offed triggering and send into pilot controller FPGA constantly; Compare with the triangular carrier count value of FPGA and to obtain brachium pontis four road pwm signals; Simultaneously last brachium pontis four road pwm signals are added inverted logic and dead band logic, obtain down brachium pontis four road pwm signals.

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