CN102843053B - Three-dimensional spatial vector based switch power amplifier of magnetic bearing system - Google Patents
Three-dimensional spatial vector based switch power amplifier of magnetic bearing system Download PDFInfo
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- CN102843053B CN102843053B CN201210284947.0A CN201210284947A CN102843053B CN 102843053 B CN102843053 B CN 102843053B CN 201210284947 A CN201210284947 A CN 201210284947A CN 102843053 B CN102843053 B CN 102843053B
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Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C32/00—Bearings not otherwise provided for
- F16C32/04—Bearings not otherwise provided for using magnetic or electric supporting means
- F16C32/0406—Magnetic bearings
- F16C32/044—Active magnetic bearings
- F16C32/0444—Details of devices to control the actuation of the electromagnets
- F16C32/0457—Details of the power supply to the electromagnets
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
- H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
- H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
- H02M7/53875—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current with analogue control of three-phase output
- H02M7/53876—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current with analogue control of three-phase output based on synthesising a desired voltage vector via the selection of appropriate fundamental voltage vectors, and corresponding dwelling times
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
- H02M7/539—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters with automatic control of output wave form or frequency
- H02M7/5395—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters with automatic control of output wave form or frequency by pulse-width modulation
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C32/00—Bearings not otherwise provided for
- F16C32/04—Bearings not otherwise provided for using magnetic or electric supporting means
- F16C32/0406—Magnetic bearings
- F16C32/044—Active magnetic bearings
- F16C32/0444—Details of devices to control the actuation of the electromagnets
- F16C32/0451—Details of controllers, i.e. the units determining the power to be supplied, e.g. comparing elements, feedback arrangements with P.I.D. control
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- General Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Mechanical Engineering (AREA)
- Magnetic Bearings And Hydrostatic Bearings (AREA)
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
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, for carrying out ACTIVE CONTROL to the output current of magnetic bearing coil.
Background technology
High-speed magnetic levitation motor replaces traditional mechanical bearing owing to adopting magnetic suspension bearing, has that rotating speed is high, without friction, without the need to lubrication, energy density is high, size is little etc., and advantage has broad application prospects.Power amplifier is as the actuator of high-speed magnetic levitation motor magnetic bearing control system, and its energy ezpenditure is maximum, and reducing the energy loss of power amplifier, improving integrated level, increase reliability is one of main object of Designing power amplifier.
In order to improve the efficiency of power amplifier, high-speed magnetic levitation motor magnetic bearing control system generally adopts switch power amplifier.The implementation producing circuit according to pulse width modulating signal is different, and magnetic bearing switch power amplifier is divided into analogue device to realize and Digital Implementation two kinds.Full bridge structure shown in existing magnetic bearing control system power amplifier many employings Fig. 1, adopts two traditional level PWM pulse duration modulation method output current ripples very large, produces larger iron loss and copper loss in electromagnetic bearing.
In Chinese patent " ZL200510012131.2 " disclosed " a kind of low-ripple switch power amplifier for permanent magnet biased electromagnetic-bearing ", adopt analogue device to achieve the function of three-level pwm pulse-width modulation, reduce ripple loss; But the power amplifier loss adopting analogue device to build is comparatively large, volume is comparatively large, must hardware adjustment be carried out to change PWM mode simultaneously, using inconvenience.
In Chinese patent " 200610114390.0 " disclosed " a kind of switch power amplifier for magnetic suspension flywheel magnetic bearing system ", employing FPGA+DSP is controller, and adopt tri-state PWM mode, data-handling capacity is strong, and current ripples is little; But it needs at lower bridge two power switch pipe source electrodes with reference to being connected in series noninductive power resistor respectively between ground, control to sample to current signal when loop afterflow by FPGA, control mode is complicated, programming realization 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 to increase all to some extent.
In Chinese patent " 200710120705.7 " disclosed " a kind of for the switch power amplifier of magnetic bearing system based on space vector ", adopt three bridge arm structures shown in Fig. 2 as main circuit, adopt FPGA+DSP as controller, utilize two-dimensional space vector modulation method, greatly reduce current ripples loss, and middle brachium pontis is public by two magnetic bearing coil institutes, decreases the quantity of power switch pipe, reduces the volume of power amplifier; But its switching tube quantity is still more, power amplifier volume is still larger, if the quantity of switching tube and the volume of power amplifier will be reduced further, the method will be restricted, and the method can only realize the vector adjustment in two-dimensional space, and it utilizes sampling resistor to carry out current sample, and when supply power voltage is higher, isolation effect is weak simultaneously, fail safe is not high, and anti-interference is also not strong.
Above-mentioned several patent does not all consider the impact that PWM dead band is caused magnetic bearing voltage simultaneously, and when Dead Time is comparatively large, when modulating frequency is higher, the voltage difference accumulation that dead band is caused 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, adopt the modulation system based on three-dimensional space vectors, decrease the quantity of power tube and the volume of power amplifier, reduce the amplitude of ripple, reduce the loss of magnetic bearing system, there is fast response time simultaneously, the feature of flexible in programming; The method of PWM dead band real-Time Compensation is adopted to improve control precision; Adopt high-precision current transformer as current feedback testing circuit, control electricity (light current) and power electricity (forceful electric power) isolation effect good, fail safe is high, and accuracy of detection is high, and strong interference immunity, responsive bandwidth are high, be easy to realization.
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 bridge legs power main circuit, current feedback testing circuit, signal conditioning circuit, signal filter circuit, wherein:
Controller: sampled by the current feedback signal of inner AD conversion interface to the displacement signal of displacement transducer and magnetic bearing three coils, the displacement signal that utilization collects and magnetic bearing rotor reference displacement signal do difference, magnetic bearing position error signal is calculated according to control algolithm, generate electric current expected signal value, electric current expected signal value and current feedback signal value are carried out doing difference, obtain error size, utilize dead-time compensation algorithm to calculate PWM Dead Time simultaneously and accumulate the magnetic bearing coil voltage rising value or drop-out value that cause, and convert this rising value or drop-out value to electric current correction value, by this electric current correction value, the error signal obtained is revised, PWM Algorithm is utilized to carry out PWM to the error signal after revising, export eight-path PWM signal (PWM1 ~ PWM8), deliver to isolated drive circuit,
Isolated drive circuit: input the pwm signal exported with controller and be connected, exports and connects with four bridge legs power main circuit, for generating the gate drive signal of power switch pipe in four bridge legs power main circuit;
Four bridge legs power main circuit: the gate drive signal exported by isolated drive circuit controls conducting and the shutoff of upper and lower brachium pontis eight power switch pipes, thus the electric current generating the expectation Current Control amount that calculates with controller proportional in three coils of magnetic bearing exports;
Three current feedback testing circuits: input connects with four bridge legs power main circuit, export and connect with modulate circuit, are respectively used to three coil current feedback signals of the magnetic bearing detecting four bridge legs power main circuit;
Signal conditioning circuit: export and connect with signal filter circuit, carries out level deviation for the current feedback signal exported three current feedback testing circuits, zooms in or out;
Signal filter circuit: input to nurse one's health with signal conditioning circuit after signal be connected, for the noise signal in filtering input signal, export and connect with the AD conversion interface of controller, under the control of master controller DSP, three current feedback signals that signal filter circuit exports are sampled.
Described controller is made up of DSP and FPGA, wherein DSP is as master controller, primary responsibility completes magnetic bearing rotor-position signal control algolithm, dead-time compensation algorithm and three-dimensional space vectors algorithm, FPGA is as the interface chip of DSP periphery, as pilot controller, be mainly used to the order receiving DSP, produce the pwm signal needed.DSP applying three-dimensional means of space vector representation calculates the ON time that on four bridge legs main circuit, brachium pontis four power switch pipes are expected, and utilize this ON time calculate conducting trigger instants and turn off trigger instants, and using shutoff trigger instants as corresponding comparison value deliver to FPGA be used for generate pwm signal, the FPGA cycle that produces is that the triangular carrier of T counts, accept four comparison values that DSP sends here simultaneously and compare the pwm signal PWM1 ~ PWM4 obtaining upper brachium pontis four power switch pipes respectively with triangular carrier count value, obtain after the die-out logic that the signal PWM5 ~ PWM8 of lower brachium pontis four power switch pipes is produced through FPGA by PWM1 ~ PWM4 and inverted logic.
Described dead-time compensation algorithm step is:
1. rated current positive direction from left to right, calculates according to the sense of current of A, B, C, D 4 the voltage difference △ U that each point compensates front and back
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 along with the increase of rotating speed, T
dead_timerepresent Dead Time, U represents the amplitude of supplying DC voltage, and T represents carrier cycle.
2. the electric current flowing through A, B, C, D 4 is respectively I
1, I
2-I
1, I
3-I
2,-I
3, when the sense of current flowing through A, B, C, D 4 is timing, voltage compensation value is just, when the sense of current is for time negative, voltage compensation value is negative.So the voltage compensation value of A, B, C, D 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 represents sign function.
3. the voltage compensation value calculating 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 dead-time compensation algorithm to carry out dead band and revises the correcting current error amount obtaining magnetic bearing three coils;
2. utilize three correcting current error amounts carry out PID arithmetic obtain three-dimensional space vectors expect voltage-regulation amount;
3. DSP is according to the size and Orientation of the voltage-regulation amount of the three-dimensional space vectors expectation obtained, and determines the interval residing for output voltage vector;
4. obtain according to residing interval computation the ON time that on four bridge legs main circuit, brachium pontis four power tubes are expected, and then calculate the conducting trigger instants of power switch pipe and turn off trigger instants;
5. turn off trigger instants by four that obtain and send into pilot controller FPGA, compare with the triangular carrier count value of FPGA and obtain upper brachium pontis four road pwm signal, inverted logic and die-out logic are added to upper brachium pontis four road pwm signal simultaneously, obtain lower brachium pontis four road pwm signal;
Control principle of the present invention: for power amplifier of magnetic bearing switch, by controlling the turn-on and turn-off of eight power switch pipe VT1 ~ VT8 on four brachium pontis, conducting and the shutoff of the coil 1 of magnetic bearing, coil 2 and coil 3 can be controlled simultaneously, simultaneously in order to avoid the power switch pipe up and down of same brachium pontis leads directly to, necessarily require signal inversion corresponding to the upper and lower power switch pipe of four bridge legs and add dead band time delay, the signal that namely VT1 ~ VT8 is corresponding: S1 and S5, S2 and S6, S3 and S7, S4 and S8 are anti-phase and with dead band time delay.As shown in Figure 3 and Figure 5, wherein the dashed region of Fig. 5 arrow indication represents dead band, and Dead Time was determined according to the service time of device and turn-off time; H and L represents pwm signal when two switching tubes up and down of any one brachium pontis in four bridge legs power main circuit do not add dead band respectively, H1 and L1 represents pwm signal when two switching tubes up and down of any one brachium pontis in four bridge legs power main circuit add dead band respectively.Different logical values (0 or 1) is got by controlling upper brachium pontis four power switch pipe gate drive signals (S1S2S3S4), 16 kinds of states can be combined into, comprising 14 non-zero basic vectors and two zero basic vectors, space voltage vector corresponding to each on off state is by same interval three coil voltage Vector modulation.Its spatial distribution as shown in Figure 6.Owing to adopting four bridge legs structure, so the region of whole voltage vector is divided into the factorial of 24(4) individual interval, 24 interval division principles are according to ensureing that the principle that switching tube minimum in adjacent twice handoff procedure participates in turn-on and turn-off is determined successively according to 16 basic vectors, namely only have a half-bridge to participate in turn-on and turn-off in four brachium pontis, namely produce minimum switching loss; Simultaneously in order to make the space vector harmonic wave of generation minimum, each road voltage vector adopts symmetrical expression distributed architecture in each switch periods, each switch periods is divided into five parts, wherein three parts are the ON time of three non-zero basic voltage vectors, if this three part-times sum is less than switch periods, then this difference is averagely allocated to two zero basic vectors.Adopt nine symmetrical section space vector algorithms, in the action time that the beginning of each switch periods and ending phase are two zero basic vectors, other three non-zero basic voltage vectors will be divided into the left and right sides that two parts are distributed in zero basic vector symmetrically, namely according to nine segmentation sequential action shown in zero basic vector 1 → non-zero basic vectors 1 → non-zero basic vectors 2 → non-zero basic vectors 3 → zero basic vector 2 → non-zero basic vectors 3 → non-zero basic vectors 2 → non-zero basic vectors 1 → zero basic vector 1.The Rule of judgment in each interval corresponding basic voltage vectors, basic voltage vectors sequence of operation and each interval is as shown in table 1.In table 1, Ux, Uy, Uz represent the reference voltage regulated quantity that in three-dimensional space vectors, three coils are expected respectively, Vi (i=0,1,2 ... 15) 16 basic vectors are represented respectively.24 interval division principles are according to ensureing that the principle that switching tube minimum in adjacent twice handoff procedure participates in turn-on and turn-off is determined successively according to 16 basic vectors.Ti (i=0, 1, 2 ... 15) action time of 16 basic vectors is represented respectively, T represents carrier cycle, U is the amplitude of supplying DC voltage, affiliated interval Rule of judgment is more than or equal to zero according to the ON time of each basis vector in interval, drop on the 5th interval for reference voltage vector Vref to be described: the basic voltage vectors in this interval is V14, V6 and V4, its basic role time is respectively T14, T6 and T4, namely (S1 S2 S3 S4) gets the time of (1110) is T14, namely three coil voltages are the time of (00U) is T14, the time that (S1 S2 S3 S4) gets (0110) is T6, namely three coil voltages are the time of (-U0U) is T6, the time that (S1 S2 S3 S4) gets (0100) is T4, namely three coil voltages are the time of (-UU0) is T4, according to vector equivalent equation Vref × T=T14 × V14+T10 × V6+T8 × V4, following equation group can be converted into:
Solving equations obtains:
According to T14 >=0, T6 >=0 and T4 >=0 obtain reference voltage vector Vref drop on the 5th interval time interval judgement condition:
Rule of judgment interval belonging to other 23 can similarly obtain successively.
The interval voltage sequence of operation of table 1 and interval judgement condition
According to interval division condition belonging to shown in table 1, judge to expect voltage-regulation amount Vref(Ux Uy Uz) belonging to interval, then calculate the action time of each basic voltage vectors according to interval basic voltage vectors sequence of operation.Such as: if expect voltage-regulation amount Vref(Ux Uy Uz), satisfy condition Ux+Uy >=0, Uy≤0, Uy+Uz >=0, then drop on the 3rd interval according to the known reference voltage vector Vref of upper table, minimum and the harmonic wave minimum principle according to switching loss, the basic voltage vectors in this interval should be taken as (V14 as shown in Table 1, V10, V8), then the action effect of Vref can pass through basic vector (V14, V10, V8) effect synthesis, that is: Vref × T=T14 × V14+T10 × V10+T8 × V8, wherein the action time of V14 is T14, the action time of V10 is T10, the action time of V8 is T8.Wherein Vi (i=0,1,2 ... 15) 16 basic vectors are represented respectively, Ti (i=0,1,2 ... 15) represent the action time of 16 basic vectors respectively, T represents carrier cycle.Because the present invention adopts nine symmetrical section space vector algorithms, in beginning and the ending phase of each switch periods, be the action time of zero vector V15 half: 1/2 × T15=t
0/ 4, and the interlude section of switch periods is this vector V of zero-base 0 action time: T0=t
0/ 2.Wherein t
0be sum action time of zero basic vector (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, namely three coil voltages are the time of (00U) is T14, the time that (S1 S2 S3 S4) gets (1010) is T10, namely three coil voltages are the time of (U-UU) is T10, the time that (S1 S2 S3 S4) gets (1000) is T8, namely three coil voltages are the time of (U00) is T8, the time that (S1 S2 S3 S4) gets (0000) is T0, namely three coil voltages are the time of (000) is T0, the time that (S1 S2 S3 S4) gets (1111) is T15, namely three coil voltages are the time of (000) is T15.Wherein U is the amplitude of supplying DC voltage.Vector equivalent equation Vref × T=T14 × V14+T10 × V10+T8 × V8, can be converted into following equation group:
Can be obtained by solving equation group:
Thus T15=T0=(T-T14-T10-T8 action time of two zero vectors can be obtained)/2, so the high level width of S1 signal is: T15+T14+T10+T8=t
0/ 2+t
1+ t
2+ t
3; The high level width of S2 signal is: T15+T14=t
0/ 2+t
1; The high level width of S3 signal is: T15+T14+T10=t
0/ 2+t
1+ t
2; The high level width of S4 signal is: T15=t
0/ 2; Wherein t
0sum action time of zero basic vector (V0 and V15), t
1, t
2and t
3be respectively three non-zero basic vectors corresponding to Vref according to turn-on sequence action time successively, namely for this routine t
1=T14, t
2=T10, t
3=T8, t
0=T-T14-T10-T8, t
1, t
2and t
3size determined by the size and Orientation of Vref, the ON time of each power switch pipe can be obtained according to the high level width of the corresponding triggering signals of upper brachium pontis four power switch pipes; Utilize the ON time of each power switch pipe can calculate conducting trigger instants in conjunction with symmetry and turn off trigger instants, owing to adopting symmetrical structure in the present invention, so only need obtain the shutoff trigger instants of brachium pontis four switching tubes, namely 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, wherein t
trig_off_1, t
trig_off_2, t
trig_off_3, t
trig_off_4the shutoff trigger instants of corresponding upper brachium pontis four power switch pipes respectively, the space vector that in like manner can obtain other intervals under other states realizes, and then realizes the control to magnetic bearing coil current.ON time and the shutoff trigger instants in other intervals are as shown in table 2, and X, Y, Z in table 2 represent Ux, Uy, Uz respectively, and T represents carrier cycle, and U is the amplitude of supplying DC voltage.
The each interval ON time of table 2 and shutoff trigger instants table
The present invention realize with existing analogue device or Digital Implementation magnetic bearing switch power amplifier compared with, advantage is:
(1) control permanent magnet biased magnetic bearing and usually need control five degrees of freedom, need control two radial direction magnetic bearings and an axial magnetic bearing totally five road magnetic bearing coils, the present invention is by adopting the topological structure of three-dimensional space vectors control technology and four bridge legs power main circuit, eight power tubes are utilized independently to control three independently coil currents, the power tube that the magnetic bearing system of control 5 coils is needed is reduced to 14 by 20, and (a four bridge legs power main circuit controls a radial direction magnetic bearing x respectively, y direction and axial magnetic bearing direction be totally three coils, need 8 power tubes, three brachium pontis power main circuits control the two-way coil in another radial direction magnetic bearing x, y direction, need 6 power tubes, totally 14 power tubes), decrease power tube quantity and power amplifier volume, improve integrated level, reduce 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 three-dimensional space vector modulation, using DSP as master controller, give full play to the advantage that its computing capability is strong and peripheral interface is abundant, there is system responses fast, FPGA is as pilot controller, the double peripheral expansion being DSP, gives full play to the advantage of its flexible in 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 A, B, C, D 4
a, △ U
b, △ U
c, △ U
dthe electric current wherein flowing through A point equals the electric current flowing through coil 1, the electric current that the electric current flowing through B point equals coil 2 deducts the electric current of coil 1, and the electric current that the electric current flowing through C point equals to flow through coil 3 deducts the electric current flowing through coil 2, and the electric current flowing through D point equals the opposite number of the electric current flowing through coil 3.Obtain according to the electric current of each point the voltage compensation value that corresponding voltage compensation value calculates three coils to be 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 respectively to the electric current correction value △ I of three coils divided by coil resistance
1, △ I
2, △ I
3.When the supply power voltage of the coil of magnetic bearing is larger, Dead Time is larger, dead zone voltage impact is comparatively large, by real-time dead area compensation, can reach the object improving control precision.
Accompanying drawing explanation
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 hardware composition frame chart of the present invention;
Fig. 4 is controller of the present invention composition and flow chart;
Fig. 5 is that pwm signal produces and adds the schematic diagram in dead band;
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 three-dimensional space vectors algorithm of the present invention;
Fig. 8 is three-dimensional space vectors algorithm flow chart of the present invention;
Fig. 9 is 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 bridge legs power main circuit, current feedback testing circuit, signal conditioning circuit, signal filter circuit, wherein: controller is sampled by the current feedback signal of inner AD conversion interface to the displacement signal of displacement transducer and magnetic bearing three coils, the displacement signal that utilization collects and magnetic bearing rotor reference displacement signal do difference, magnetic bearing position error signal is calculated according to control algolithm, generate electric current expected signal value, electric current expected signal value and current feedback signal value are carried out doing difference, obtain error size, utilize dead-time compensation algorithm to calculate PWM Dead Time simultaneously and accumulate the magnetic bearing coil voltage rising value or drop-out value that cause, and convert this rising value or drop-out value to electric current correction value, by this electric current correction value, the error signal obtained is revised, PWM Algorithm is utilized to carry out PWM to the error signal after revising, export eight-path PWM signal (PWM1 ~ PWM8), deliver to isolated drive circuit, PWM1 ~ PWM8 signal that input and the controller of isolated drive circuit export is connected, and exports the gate drive signal S1 ~ S8 of power switch pipe VT1 ~ VT8 in four bridge legs power main circuit, is directly connected with the grid of four bridge legs power main circuit switch pipe, the conducting of brachium pontis and lower brachium pontis eight power switch pipe VT1 ~ VT8 and shutoff in gate drive signal S1 ~ S8 control that four bridge legs power main circuit is exported by isolated drive circuit, thus in three coils of magnetic bearing, generate the electric current proportional with Current Control amount export, the input of current feedback testing circuit is directly in series with four bridge legs power main circuit, and output connects signal conditioning circuit, for detecting three coil current feedback signals of the magnetic bearing of four bridge legs power main circuit, modulate circuit connects with signal filter circuit, carries out level deviation for the current feedback signal exported three current feedback testing circuits, zooms in or out, signal filter circuit nurse one's health with signal conditioning circuit after signal be connected, for the noise signal in filtering input signal, the AD conversion mouth that three current feedback signals of output are connected to controller gathers.
Controller comprises master controller DSP and pilot controller FPGA.Master controller DSP utilizes the current feedback signal of built-in AD conversion interface to the displacement signal of displacement transducer and magnetic bearing three coils to sample, the displacement signal that utilization collects and magnetic bearing rotor reference displacement signal do difference, magnetic bearing position error signal is calculated according to control algolithm, generate electric current expected signal value, and this current expected value and current feedback values are done difference obtain three current error signals, then DSP adopts dead-time compensation algorithm to calculate PWM Dead Time and accumulates the magnetic bearing coil voltage rising value or drop-out value that cause, and convert this rising value or drop-out value to electric current correction value, by this electric current correction value, three current error signals are revised, utilize three revise after error carry out PID arithmetic obtain three-dimensional space vectors expect voltage-regulation amount.The size and Orientation of the voltage-regulation amount that DSP expects according to the three-dimensional space vectors obtained, four road comparison values are generated according to three-dimensional space vectors algorithm, the count value of four road comparison values and triangular carrier is compared, obtain PWM1 ~ PWM4 signal of brachium pontis four power switch pipes, inverted logic and die-out logic are added to four road pwm signals simultaneously, obtain PWM5 ~ PWM8 signal of lower brachium pontis four pipes; The gate drive signal of the power switch pipe of four bridge legs power amplifier main circuit 3 is generated: S1 ~ S8 through isolated drive circuit 2, wherein S1 and S5, S2 and S6, S3 and S7, S4 and S8 are anti-phase respectively and add dead band, conducting and the shutoff of eight power switch pipes is controlled by S1 ~ S8, current feedback testing circuit 4, by the current value of magnetic bearing coil in isolation detection four bridge legs power main circuit 3, obtains the current feedback signal of coil.
Wherein VT1 and VT5 forms the first brachium pontis; VT2 and VT6 forms the second brachium pontis; VT3 and VT7 forms the 3rd brachium pontis; VT4 and VT8 forms four bridge legs, and magnetic bearing coil 1 is connected between the first brachium pontis and the second brachium pontis, and coil two-end-point is respectively A and B, and coil both end voltage is U
aB; Magnetic bearing coil 2 is connected between the second brachium pontis and the 3rd brachium pontis, and coil two-end-point is respectively B and C, and coil both end voltage is U
bC; Magnetic bearing coil 3 is connected on the 3rd between brachium pontis and four bridge legs, and coil two-end-point is respectively C and D, and coil both end voltage is U
cDnamely the second brachium pontis and the 3rd brachium pontis are the public brachium pontis of two magnetic bearing coils, B and C 2 is two magnetic bearing coil common connection point, the drive singal (S1, S2, S3, S4) of upper brachium pontis power switch pipe anti-phase with the drive singal (S5, S6, S7, S8) of lower brachium pontis power switch pipe respectively and add die-out logic with prevent upper and lower bridge arm lead directly to.To contact respectively in magnetic bearing coil 1, magnetic bearing coil 2 and magnetic bearing coil 3 high precision electric current transducer, effectively will control electricity (light current) and power electricity (forceful electric power) is isolated, while magnetic test coil electric current.
As shown in Figure 4, controller of the present invention is made up of master controller DSP and pilot controller FPGA.DSP is as master controller, and primary responsibility completes magnetic bearing rotor-position signal control algolithm, dead-time compensation algorithm and three-dimensional space vectors algorithm, FPGA, as the interface chip of DSP periphery, as pilot controller, is mainly used to the order receiving DSP, produces the pwm signal needed, DSP utilizes built-in AD interface to carry out feedback current sampling and displacement sampling, DSP utilizes the displacement signal of displacement signal and the magnetic bearing rotor expectation collected to do difference, after control algolithm is carried out to magnetic bearing position error signal, generate current expected value, this is expected that current value and the sampled value of current feedback signal before obtain three current error values after carrying out doing difference by DSP, then DSP utilizes dead-time compensation algorithm to calculate PWM Dead Time and accumulates the magnetic bearing coil voltage rising value or drop-out value that cause, and convert this rising value or drop-out value to electric current correction value, by this electric current correction value, three current error signals are revised, utilize three revise after error carry out PID arithmetic obtain three-dimensional space vectors expect voltage-regulation amount.The voltage-regulation amount size and Orientation that DSP expects according to the three-dimensional space vectors obtained, applying three-dimensional means of space vector representation calculates the ON time that on four bridge main circuits, brachium pontis four power switch pipes are expected, and utilize this ON time calculate conducting trigger instants and turn off trigger instants, and using shutoff trigger instants as corresponding comparison value deliver to FPGA be used for generate pwm signal, the FPGA cycle that produces is that the triangular carrier of T counts, accept four comparison values that DSP sends here to compare with triangular carrier count value respectively simultaneously, if the triangle that the comparison value sent here is greater than generation carries count value, then export high level, otherwise then output low level, obtain the pwm signal PWM1 ~ PWM4 of brachium pontis four power switch pipes thus, obtain after the die-out logic that the signal PWM5 ~ PWM8 of lower brachium pontis four power switch pipes is produced through FPGA by PWM1 ~ PWM4 and inverted logic.
As shown in Figure 5, PWM formation logic when not adding dead band is: when the comparison value that DSP sends here is greater than triangular carrier count value, and upper brachium pontis pwm signal is high level, and lower brachium pontis pwm signal is low level; When the comparison value that DSP sends here is less than triangular carrier count value, upper brachium pontis pwm signal is low level, and lower brachium pontis pwm signal is high level; Short circuit is caused in order to prevent two power tubes up and down of same brachium pontis from opening simultaneously, die-out logic must be added, namely go up pwm signal time delay a period of time conducting on the basis of not adding dead band of brachium pontis power switch pipe, turn off on time, lower brachium pontis power switch pipe is shutoff, the conducting of time delay a period of time on time on the basis of not adding dead band.The change in voltage that interpolation dead band causes will utilize dead-time compensation algorithm correction, and dead-time compensation algorithm step is:
1. rated current positive direction from left to right, calculates according to the sense of current of A, B, C, D 4 the voltage difference △ U that each point compensates front and back
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 along with the increase of rotating speed, T
dead_timerepresent Dead Time, U represents the amplitude of supplying DC voltage, and T represents carrier cycle.
2. the electric current flowing through A, B, C, D 4 is respectively I
1, I
2-I
1, I
3-I
2,-I
3, when the sense of current flowing through A, B, C, D 4 is timing, voltage compensation value is just, when the sense of current is for time negative, voltage compensation value is negative.So the voltage compensation value of A, B, C, D 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 represents sign function.
3. the voltage compensation value calculating 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 (S1 and S5, S2 and S6, S3 and S7, S4 and S8 are anti-phase after adding dead band respectively) of S1, S2, S3 and S4, four brachium pontis can be combined into 16 kinds of on off states, comprising two zero vectors and 14 non-zero.The voltage U on the magnetic bearing coil be connected between brachium pontis mid point A, B
aBbe used as the voltage of the X-axis of one end magnetic bearing XY plane, the voltage U on the magnetic bearing coil be connected between brachium pontis mid point B, C
bCbe used as the voltage of the Y-axis of one end magnetic bearing XY plane, the voltage U on the magnetic bearing coil be connected between brachium pontis mid point C, D
cDbe used as axial voltage, i.e. the voltage of Z axis.16 kinds of on off states (0000), (0001) ..., (1111) correspond to outputting ten six basic voltage vectors V0, V1 respectively ..., V15.Wherein V0 and V15 is two zero basic voltage vectors, and V1 ~ V14 is corresponding 14 non-zero basic voltage vectors respectively, and these 16 basic voltage vectors are divided into 24 intervals 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 synthesized by three non-zero basic voltage vectors in each interval.
Three-dimensional space vectors algorithm is adopted to control four bridge legs power amplifier main circuit, three coils of magnetic bearing there will be charging in the course of the work, the state different with free afterflow three kinds of discharging, and the four bridge legs power amplifier main circuit that this feature makes three-dimensional space vectors algorithm control has the advantage that ripple is little, loss is little that three-level control principle method has.But the present invention is while possessing above-mentioned advantage, and the 3rd brachium pontis that forms of the second brachium pontis of forming of VT2 and VT6 and VT3 and VT7 share by two magnetic bearing coils, the Simultaneous Switching loss decreasing power switch pipe quantity also reduces greatly.
The present invention adopts nine symmetrical section space vector pulse width modulation modes, each basic vector is divided into nine sections in each switch periods, in beginning and the ending phase of each switch periods, it is zero vector V15 action time, and the interlude section of switch periods is this vector V of zero-base 0 action time, the ON time of zero vector is divided equally by zero vector V15 and V0, 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, the sequence of operation of each basic vector in each switch periods and time are symmetrical, the each road pulse-width signal produced also is symmetrical.T
0sum action time of zero basic vector (V0 and V15), t
1, t
2and t
3be respectively residing interval three non-zero basic vectors according to turn-on sequence action time successively.In 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 ensures that the conversion of each on off state all only has one to change, namely when eight power switch pipes are transformed into another kind of on off state from a kind of on off state, a brachium pontis is only had to participate in the change of current, so not only can reduce on-off times, and can switching loss be reduced.
As shown in Figure 8, the software simulating flow process 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 dead-time compensation algorithm to carry out dead band and revises the correcting current error amount obtaining magnetic bearing three coils;
2. utilize three correcting current error amounts carry out PID arithmetic obtain three-dimensional space vectors expect voltage-regulation amount;
3. DSP is according to the size and Orientation of the voltage-regulation amount of the three-dimensional space vectors expectation obtained, and determines the interval residing for output voltage vector;
4. obtain according to residing interval computation the ON time that on four bridge legs main circuit, brachium pontis four power tubes are expected, and then calculate the conducting trigger instants of power switch pipe and turn off trigger instants;
5. turn off trigger instants by four that obtain and send into pilot controller FPGA, compare with the triangular carrier count value of FPGA and obtain upper brachium pontis four road pwm signal, inverted logic and die-out logic are added to upper brachium pontis four road pwm signal simultaneously, obtain lower brachium pontis four road pwm signal.
In the course of work of magnetic bearing, in three-dimensional space vectors algorithm, in each interval, the sequence of operation of basic voltage vectors becomes corresponding corresponding relation with the switching signal of power switch pipe, so first will calculate the current error signal of three coils of magnetic bearing in the middle of working control; Then carry out dead band correction according to the Dead Time of pwm signal design to three current error signals, the error after utilization correction carries out the voltage-regulation amount that PID arithmetic obtains three-dimensional space vectors expectation, judges which voltage vector is positioned at interval according to table 1; T action time of three basic voltage vectors is obtained according to residing range lookup table 2
1, t
2, t
3, then utilize formula t
0=T-t
1-t
2-t
3calculate t
0, and then the shutoff trigger instants t of four power switch pipes is obtained according to table 2
trig_off_1, t
trig_off_2, t
trig_off_3, t
trig_off_4; The shutoff trigger instants obtained is delivered to FPGA as comparison value, compare with the triangular carrier count value of FPGA, if the triangle that the comparison value sent here is greater than generation carries count value, then export high level, otherwise then output low level, obtain the pwm signal PWM1 ~ PWM4 of brachium pontis four power switch pipes thus, obtain after the die-out logic that the signal PWM5 ~ PWM8 of lower brachium pontis four power switch pipes is produced through FPGA by PWM1 ~ PWM4 and inverted logic.
The PWM carrier cycle adopted in the present invention is 20kHz, in this enforcement, the crystal oscillator of FPGA is 40MHz, because this enforcement adopts symmetrical PWM ripple, so the triangular carrier adopted is symmetric triangular ripple, so maximum triangular carrier count value is 40M/20K/2=1000, direct voltage U correspondence 1000, the cycle T correspondence 2000 of symmetric triangular carrier wave.DSP calculates three error signal question blanks 1 after revising according to dead band and judges residing interval, obtains t action time of three non-zero basic vectors according to residing interval query table 2
1, t
2and t
3, and then then utilize formula t
0=T-t
1-t
2-t
3calculate t
0, according to t
0, t
1, t
2and t
3the turn-off time of brachium pontis four switching tubes in calculating, such as, to the reference vector Vref being positioned at the 3rd interval in Fig. 7, the t calculated
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, wherein t
trig_off_1, t
trig_off_2, t
trig_off_3, t
trig_off_4in the shutoff moment of corresponding upper brachium pontis four power switch pipes respectively, above-mentioned four values are assigned to respectively four comparison values CMP1, CMP2, CMP3 and CMP4 and send into FPGA for generation of the pwm signal needed.For the example of in actual implementation process, the three-dimensional space vectors method course of work is described below: suppose that DSP is by after the current signal collection of three of magnetic bearing coils, three the current error values obtained after overcurrent dead band is revised are respectively: Ux=300, Uy=-100, Uz=200, due to Ux+Uy>=0, Uy≤0, Uy+Uz>=0, question blank 1 this vector known is positioned at the 3rd interval, due to T=2000, U=1000, can obtain according to residing interval query table 2: 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 is averagely allocated to V15 and V0.According to t
0, t
1, t
2and t
3t can be obtained
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, using the shutoff trigger instants that obtains as comparison value, 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 comparing the signal PWM1 ~ PWM4 that can obtain upper brachium pontis four power switch pipes with triangular carrier by four comparison values feeding FPGA, the signal PWM5 ~ PWM8 of lower brachium pontis four power switch pipes obtains by after PWM1 ~ PWM4 interpolation die-out logic and inverted logic.
As shown in Figure 9, current feedback testing circuit of the present invention is given.In Fig. 9 I+and I-represent electric current respectively to flow into end and outflow of bus current end, by I+and I-be concatenated in the magnetic bearing coil of Fig. 3 respectively, I+wiring loop current flows into end, I-wiring loop current outflow end, distinguishes "+" and "-" of each current sensor in corresponding diagram 3.Current sensor adopts multrirange current sensor LA28-NP, the range selected is 5A, be connected respectively with 7 pin with 8 pin, 5 pin with 9 pin, 4 pin with 10 pin, 3 pin by its 2 pin, 1 pin and 6 pin unsettled, turn ratio selects 5:1000, and during full scale, secondary side exports the current signal of 25mA, current signal is converted into voltage output signal I _ COIL by the resistance R1 of external 360 ohm, and at resistance two ends and the electric capacity C1 connecting a 0.01uf carries out simple filtering to it.Electric current primary side and secondary side are carried out electrical isolation, strong interference immunity by current sensor, and fail safe is good, and its bandwidth reaches 150kHz, and accuracy of detection reaches ± and 0.5%, and be easy to realize.
As shown in Figure 10, signal conditioning circuit of the present invention and signal filter circuit circuit is given.The output of the current feedback testing circuit shown in its input I _ COIL map interlinking 9, exports the AD mouth meeting DSP.Because the voltage that current sensor exports is of ac, in order to the scope that the AD mouth being translated into DSP can gather, i.e. 0 ~ 3.3V, need to nurse one's health, first reduce after current sensor output being added bias voltage, the operational amplifier adopted is TL084, and its inside comprises four operational amplifiers.BIAS_ I in Figure 10 represents bias voltage value, and U1A, U1B, U1C represent three operational amplifiers in TL084 respectively.Resistance R1 is used as current-limiting resistance, and resistance selects 10k, and resistance R2, R3, R5 carry out the adjustment of minification, R2 and R3 resistance selects 10k, R5 to adopt the slide rheostat of 0 ~ 20k.Then the signal after conditioning is carried out filtering, eliminate the aliasing in spectra of digital system and the interference of high-frequency noise, employing be a second-order low-pass filter, that electric capacity C1, C2 select is 0.01uf, resistance R6 and R7 resistance select 3.3k, and the cut-off frequency of low pass elects 3.1kHz as.In order to the signal after ensureing filtering is strict controlled within the scope of 0 ~ 3.3V, so before entering the AD mouth of DSP, added two back-to-back 3.3V voltage-stabiliser tube Z1 and Z2, the AD mouth that the output signal I _ TO_AD after filtering is sent to DSP gathers.
Control permanent magnet biased magnetic bearing and usually need control five degrees of freedom, need control two radial direction magnetic bearings and an axial magnetic bearing totally five road magnetic bearing coils, during working control, by x, y direction of a radial direction magnetic bearing and axial magnetic bearing totally three coils, receive successively on the coil 1 of the power of four bridge legs shown in Fig. 3 main circuit, coil 2, coil 3, adopt illustrated three-dimensional space vectors algorithm to control; The two-way magnetic bearing coil in x, y direction of another radial direction magnetic bearing is received successively on the coil 1 in three brachium pontis power main circuits shown in Fig. 2, coil 2, adopt the general spatial vector operation disclosed in 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 the systems such as magnetic levitaion motor, magnetically levitated flywheel, magnetic suspension control torque gyroscope.
Claims (4)
1. the 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 bridge legs power main circuit (3), current feedback testing circuit (4), signal conditioning circuit (5), signal filter circuit (6), wherein:
Controller (1): sampled by the current feedback signal of the inner AD conversion interface of controller to the displacement signal of displacement transducer and magnetic bearing three coils, the displacement signal that utilization collects and magnetic bearing rotor reference displacement signal do difference, magnetic bearing position error signal is calculated according to control algolithm, generate electric current expected signal value, electric current expected signal value and current feedback signal value are carried out doing difference, obtain error size, utilize dead-time compensation algorithm to calculate PWM Dead Time simultaneously and accumulate the magnetic bearing coil voltage rising value or drop-out value that cause, and convert this rising value or drop-out value to electric current correction value, by this electric current correction value, the error signal obtained is revised, three-dimensional space vectors algorithm is utilized to carry out PWM to the error signal after revising, export PWM1 ~ PWM8 and amount to eight-path PWM signal, deliver to isolated drive circuit (2),
Isolated drive circuit (2): input is connected with PWM1 ~ PWM8 signal that controller (1) exports, exports the gate drive signal S1 ~ S8 of power switch pipe VT1 ~ VT8 in four bridge legs power main circuit (3);
Four bridge legs power main circuit (3): adopt eight power switch pipes independently to control the topological structure of three coils, wherein VT1 and VT5 forms the first brachium pontis; VT2 and VT6 forms the second brachium pontis; VT3 and VT7 forms the 3rd brachium pontis; VT4 and VT8 forms four bridge legs, and magnetic bearing coil 1 is connected between the first brachium pontis and the second brachium pontis, and coil two-end-point is respectively A and B, and coil both end voltage is U
aB; Magnetic bearing coil 2 is connected between the second brachium pontis and the 3rd brachium pontis, and coil two-end-point is respectively B and C, and coil both end voltage is U
bC; Magnetic bearing coil 3 is connected on the 3rd between brachium pontis and four bridge legs, and coil two-end-point is respectively C and D, and coil both end voltage is U
cD, the drive singal (S1, S2, S3, S4) of upper brachium pontis power switch pipe anti-phase with the drive singal (S5, S6, S7, S8) of lower brachium pontis power switch pipe respectively and add die-out logic with prevent upper and lower bridge arm lead directly to;
Current feedback testing circuit (4): input connects four bridge legs power main circuit (3), output connects signal conditioning circuit (5), for detecting three coil current feedback signals of the magnetic bearing of four bridge legs power main circuit (3);
Modulate circuit (5): connect with signal filter circuit (6), carries out level deviation for the current feedback signal exported three current feedback testing circuits (4), zooms in or out;
Signal filter circuit (6): the signal after nursing one's health with signal conditioning circuit (5) is connected, for the noise signal in filtering input signal, the AD conversion mouth that three current feedback signals of output are connected to controller (1) gathers.
2. a kind of magnetic bearing system switch power amplifier based on three-dimensional space vectors according to claim 1, it is characterized in that: described controller (1) is made up of DSP and FPGA, wherein DSP is as master controller, primary responsibility completes magnetic bearing rotor-position signal control algolithm, dead-time compensation algorithm and three-dimensional space vectors algorithm, FPGA is as the interface chip of DSP periphery, as pilot controller, be mainly used to the order receiving DSP, produce the pwm signal needed, DSP utilizes dead-time compensation algorithm and three-dimensional space vectors method to calculate the ON time that on four bridge legs main circuit, brachium pontis four power switch pipes are expected, and utilize this ON time calculate conducting trigger instants and turn off trigger instants, and using shutoff trigger instants as corresponding comparison value deliver to FPGA be used for generate pwm signal, the FPGA cycle that produces is that the triangular carrier of T counts, accept four comparison values that DSP sends here simultaneously and compare the pwm signal PWM1 ~ PWM4 obtaining upper brachium pontis four power switch pipes respectively with triangular carrier count value, obtain after the die-out logic that the signal PWM5 ~ PWM8 of lower brachium pontis four power switch pipes is produced through FPGA by PWM1 ~ PWM4 and inverted logic.
3. a kind of magnetic bearing system switch power amplifier based on three-dimensional space vectors according to claim 1 and 2, is characterized in that: described dead-time compensation algorithm step is:
1. rated current positive direction from left to right, calculates according to the sense of current of A, B, C, D 4 the voltage difference △ U that each point compensates front and back
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 along with the increase of rotating speed, T
dead_timerepresent Dead Time, U represents the amplitude of supplying DC voltage, and T represents carrier cycle;
2. the electric current flowing through A, B, C, D 4 is respectively I
1, I
2-I
1, I
3-I
2,-I
3, when the sense of current flowing through A, B, C, D 4 is timing, voltage compensation value is just, when the sense of current is for time negative, voltage compensation value is negative, so the voltage compensation value of A, B, C, D 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 represents sign function;
3. the voltage compensation value calculating 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 based on three-dimensional space vectors according to claim 1 and 2, is characterized in that: described three-dimensional space vectors algorithm steps is:
1. master controller DSP calculates in real time and utilizes dead-time compensation algorithm to carry out dead band and revises the correcting current error amount obtaining magnetic bearing three coils;
2. utilize three correcting current error amounts carry out PID arithmetic obtain three-dimensional space vectors expect voltage-regulation amount;
3. DSP is according to the size and Orientation of the voltage-regulation amount of the three-dimensional space vectors expectation obtained, and determines the interval residing for output voltage vector;
4. obtain according to residing interval computation the ON time that on four bridge legs main circuit, brachium pontis four power tubes are expected, and then calculate the conducting trigger instants of power switch pipe and turn off trigger instants;
5. turn off trigger instants by four that obtain and send into pilot controller FPGA, compare with the triangular carrier count value of FPGA and obtain upper brachium pontis four road pwm signal, inverted logic and die-out logic are added to upper brachium pontis four road pwm signal simultaneously, obtain lower brachium pontis four road pwm signal.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103078589B (en) * | 2013-01-10 | 2016-04-13 | 重庆长安汽车股份有限公司 | Dead-time compensation method and device |
| CN104638722B (en) * | 2015-02-02 | 2017-07-28 | 成都芯源系统有限公司 | Battery charging system based on digital control and control circuit thereof |
| CN106788050B (en) * | 2016-12-23 | 2023-06-20 | 广东高标电子科技有限公司 | Power device control and over-temperature protection system and method for motor controller |
| CN109959801B (en) * | 2017-12-22 | 2023-09-19 | 上海卓思智能科技股份有限公司 | NTC detection circuit for wind speed detection and wind speed measurement sensor |
| CN111988021B (en) * | 2019-05-24 | 2024-05-03 | 北京车和家信息技术有限公司 | PWM generation method and device, motor controller and vehicle |
| CN111510086B (en) * | 2020-04-30 | 2023-06-23 | 庆安集团有限公司 | Signal modulation device of H half-bridge switching power amplifier |
| CN111967453B (en) * | 2020-10-22 | 2021-01-05 | 天津飞旋科技有限公司 | Method and device for matching bearing power amplifier channel and sensor channel |
| JP7029096B1 (en) * | 2020-11-20 | 2022-03-03 | ダイキン工業株式会社 | Power supply circuit and bearing equipment equipped with it |
| CN113790212B (en) * | 2021-09-14 | 2023-07-18 | 北京泓慧国际能源技术发展有限公司 | Flywheel magnetic bearing control system and method |
| CN114448324B (en) * | 2022-01-25 | 2023-09-26 | 中国船舶集团有限公司第七二四研究所 | Method for suppressing pump up voltage of driver |
| CN114754069B (en) * | 2022-03-15 | 2023-12-12 | 格瑞拓动力股份有限公司 | Self-adaptive dead zone control method and system for radial magnetic suspension bearing |
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