CN106208880A - Direct Torque Control for the monolateral matrix converter of DC brushless motor - Google Patents

Abstract

The invention discloses the Direct Torque Control of a kind of monolateral matrix converter for DC brushless motor.In the case of the outfan of monolateral matrix converter is connected with DC brushless motor, detect the three-phase voltage of monolateral matrix converter input, obtain maximum positive and negative voltage, the rotor electrical angle of detection DC brushless motor, judge to obtain the sector at place, obtain each opposite potential and combine the actual electromagnetic torque of each phase current calculating acquisition current time, the selection carrying out being switched on or off controls, and apply voltage according to the relation between actual electromagnetic torque and the stagnant ring of its torque reference of conducting phase, form directly controlling torque.Torque can be directly controlled by the inventive method, it is achieved that the real-time control of torque, it is only necessary to a torque ring, and each phase is separately controlled, and is highly susceptible to realization and amount of calculation is the least.

Description

Direct Torque Control for the monolateral matrix converter of DC brushless motor

Technical field

The present invention relates to the method for controlling torque of a kind of changer, especially related to a kind of for DC brushless motor Direct Torque Control (Direct Torque Control, the DTC) method of monolateral matrix converter.

Background technology

Monolateral matrix converter (Single Sided Matrix Converter, SSMC) is that the matrix of a kind of simplification becomes Parallel operation, it is achieved three-phase is to many phase transformations.Every array using 6 single-way switch compositions mutually so that outfan can be with any one Input connects.Matrix converter is compared with conventional bridge converter, it is not necessary to DC energy storage electric capacity, and Applicable temperature scope is more Extensively, reliability is higher；But often need to switch more mutually, relatively costly.

Monolateral matrix converter is adapted in use to the motor that unidirectional current drives, such as brshless DC motor and switched reluctance machines Deng.It controls generally to use current hysteresis-band control mode.But it is not in systems in practice, preferable linear system due to system System, torque is not likely linear relationship with electric current, and the direct torque effect causing current hysteresis-band control is not ideal enough.And Current hysteresis-band control is not directly to control torque, and torque responsing speed may be the most not ideal enough.

Summary of the invention

In order to solve problem present in background technology, it is an object of the invention to provide a kind of for DC brushless motor The Direct Torque Control of monolateral matrix converter, can be in the higher applications of the reliability requirements such as aviation, it is achieved turn Directly the controlling and improve torque responsing speed of square.

The technical scheme is that in the case of the outfan of monolateral matrix converter is connected with DC brushless motor, As in figure 2 it is shown, carry out Direct Torque Control in the following ways:

1) three-phase voltage of monolateral matrix converter input is detected, it is thus achieved that maximum positive voltage V+ and maximum negative voltage V-；

2) the rotor electrical angle of DC brushless motor is detected, it is judged that obtain the sector at rotor electrical angle place；

3) obtain respectively by rotor electrical angle according to the relation between rotor electrical angle and the back-emf obtained by emulation Opposite potential, detection simultaneously obtains each phase current of monolateral matrix converter output, in conjunction with each opposite potential and each phase current meter Calculate the actual electromagnetic torque obtaining current time；

4) according to the sector at the rotor electrical angle place of current time, by space voltage vector selection mode to direct current without The selection respectively carrying out mutually in brush motor being switched on or off controls, and each moment motor has two to be conducted, and according to conducting phase Relation between actual electromagnetic torque and the stagnant ring of its torque reference applies voltage, forms directly controlling torque.

Torque is directly controlled by the present invention so that actual electromagnetic torque is close to nominal torque, and torque ripple is less And have quick torque response；And having only to arrange a torque ring, each phase is separately controlled, and amount of calculation is the least, easily In realization.

Described step 4) according to conducting phase actual electromagnetic torque and the stagnant ring of its torque reference between relation apply electricity Press specifically:

Under current time, for turning on biphase each phase, if its actual electromagnetic torque is less than under the stagnant ring of its torque reference Limit, then apply maximum positive voltage V+ mutually to this conducting, its actual electromagnetic torque be not below its torque reference stagnant ring lower limit and lead Logical phase and all non-conduction applying V-mutually；

For a conducting arbitrary phase in biphase, if its actual electromagnetic torque is more than its torque reference stagnant ring upper limit, then All phases are applied V-.

If being all unsatisfactory for above-mentioned two situation, then each applying voltage that holding is identical with a upper cycle mutually.

Thus, in the Direct Torque Control of DC brushless motor of the present invention, it is not required to control magnetic linkage amplitude, is i.e. not required to Want magnetic linkage ring, it is only necessary to a torque ring.Actual torque, less than increasing torque during torque ring lower limit, i.e. applies V-；Actual Torque, more than reducing torque during the torque ring upper limit, i.e. applies V-.

Described space voltage vector selection mode uses table 1 below to represent:

Table 1 space voltage vector table

Wherein, V₁～V₅Representing each voltage vector that sector is corresponding, I～VI represents each sector at rotor electrical angle place, respectively Sector position and title sequence number thereof are all fixing for those skilled in the art.When rotor is in I sector, increase electromagnetism Torque space voltage vector to be applied V₅, i.e. turn on and biphase produce space voltage vector V exactly₅Biphase, remaining sector all according to Determine shown in table 1 and increase the space voltage vector that electromagnetic torque is to be applied.

Space voltage vector in upper table 1 is all that the conduction mode represented by table 2 below turns on adjacent biphase reality Existing:

Table 2 space vector of voltage correspondence conducting phase

Wherein, A～F phase represents six phases of DC brushless motor respectively, and O represents that conducting, X represent disconnection.If generated Space voltage vector V₁, then needing to simultaneously turn on A phase and B phase, remaining phase disconnects.In conjunction with table 2, when rotor is in the IIIth fan District, now increases electromagnetic torque space voltage vector to be applied V₁, namely simultaneously turn on A phase and B phase, then when rotor is in During III sector, turning on biphase is exactly A phase and B phase, comes really according to the relation of aforementioned actual electromagnetic torque with the stagnant ring of torque reference Determining A phase, the on off state in B phase each moment, be i.e. switched on or off, C phase, D phase, E phase and F phase then remain disconnection.

The half that torque reference is nominal torque in the stagnant ring of described torque reference.

Described actual electromagnetic torque T_emxIt is calculated by below equation:

$\begin{array}{cc}{T}_{emx}=\frac{P_{emx}}{{\mathrm{\ω}}_m}=\frac{e_x{i}_x}{{\mathrm{\ω}}_m}& x=a,b,c......\end{array}$

Wherein, e_x、i_xIt is respectively phase current and opposite potential, ω_mFor mechanical angle speed, P_emxFor phase electromagnetic power, T_emxFor The electromagnetic torque of one phase.

As it is shown in figure 1, monolateral matrix converter includes 6 switch elements mutually, at any one time, open by controlling each The gate signal closed, can apply arbitrary line voltage: U to motor winding_AB,U_AC,U_BC,U_CB,U_CA,U_BA.Wherein maximum positive voltage is V +, maximum negative voltage is V-.

The mode that the present invention uses is for using conduction mode two-by-two, and control magnetic linkage track is that hexagon is not (owing to turning on phase Back-emf, magnetic linkage can automatically tend to circle), need increase torque time, apply corresponding active voltage space vector, need reduce During torque, apply zero voltage space vector.Active voltage vector can be by corresponding biphase applying V+, and remaining phase applies V-and obtains Arriving, zero voltage space vector is then all phases to be applied V-obtain.

When using monolateral matrix converter to drive, each phase is all separate, therefore can simplify further, I.e. individually each phase is controlled.Owing to using conduction mode two-by-two, the torque of the most each phase output is total specified turn The half of square, so the torque reference of each phase is just set as the half of total nominal torque, simultaneously turn on is biphase, is Determined by space voltage vector selection mode.

The invention has the beneficial effects as follows:

Torque can be directly controlled by the inventive method, it is achieved that the real-time control of torque, torque ripple is little and rings Should be fast, and phase current also can follow the positive flat-topped wave of back-emf automatically；Have only to a torque ring, and each phase is separately Control, compare the DC brushless motor of the Y-connection that voltage source inverter drives, be highly susceptible to realization and amount of calculation is the least.

Accompanying drawing explanation

Fig. 1 is monolateral matrix converter one phase motor-driven structure.

Fig. 2 is direct Torque Control structure chart.

Fig. 3 is Hexaphase brushless dc motor phasor diagram and sector division.

Fig. 4 is three phase mains and interval division thereof.

Fig. 5 is the torque simulation waveform of current hysteresis-band control.

Fig. 6 is the torque simulation waveform of Direct Torque Control.

Detailed description of the invention

The invention will be further described with embodiment below in conjunction with the accompanying drawings.

The embodiment of the present invention and operation principle process thereof are as follows:

Owing to monolateral matrix converter can only provide unidirectional current, so negative back-emf cannot be utilized to produce torque. Realizing turning on two-by-two, being necessary for meeting synchronization has biphase back-emf for just.Choose six phase brushless DC motors And control system illustrates.Control system is by speed control, torque ring controller, electric pressure selector, switch letter Number maker and power amplifier board composition.

Fig. 3 is three phase mains, can be classified as 6 intervals according to three-phase voltage amplitude, in each interval, maximum Positive voltage V+ and minimum negative voltage V-all keeps constant.The voltage swing of each phase is recorded by voltage sensor.Such as exist now 1st is interval, then V+ is V_CB, V-is V_BC, V+ and V-in concrete each interval is shown in Table 3.

V+ and V-in each interval of table 3

Interval

1

2

3

4

5

6

V+

VCB

VAB

VAC

VBC

VBA

VCA

V-

VBC

VBA

VCA

VCB

VAB

VAC

As shown in Figure 4, whole space is divided into six sectors to the phasor diagram of six-phase motor, and defines six effective skies Between vector.It is hexagon for controlling magnetic linkage track, applies space vector of voltage by table 1 mode.

Space vector of voltage V₁, V₂, V₃, V₄, V₅, V₆Respectively by simultaneously turning on AB phase, BC phase, CD phase, DE phase, EF phase, FA phase obtains.And then can be obtained by the voltage of each phase voltmeter in each interval, namely opening in system block diagram Close table, as shown in table 2.

Speed control Negotiation speed sensor obtains the speed feedback value of motor, with the difference of setting speed through PI link Obtaining total nominal torque, the half of the most total nominal torque is the torque reference value of conducting phase, in this reference value being The heart arranges a torque ring.Phase current is recorded by current sensor, obtains rotor electrical angle by encoder and judges fan District, then tables look-up and obtains opposite potential, (1) calculate the output torque of each phase, if in this sector, this phase should turn on, then This phase is modulated, the most all the time it is applied V-.Modulated process is for when output torque is less than torque ring lower limit, executing for this phase Add V+, when output torque is more than the torque ring upper limit, apply V-for this phase.

From Fig. 5, Fig. 6 be 2000rpm motor torque reference be simulation waveform during 10N m, it appeared that Hysteresis Current control The peak-to-peak value of the torque ripple of system is about 1N m, and the torque ripple peak-to-peak value of Direct Torque Control only has 0.3N about m, Embody the performance that Direct Torque Control is excellent.

Thus, motor torque is directly controlled by the present invention, and each phase is separately controlled, and utilizes the maximum positive and negative line of power supply Voltage is as machine phase voltages, it is thus achieved that good torque characteristics, and whole amount of calculation is the least, it is not necessary to complicated coordinate transform, to place Reason device is less demanding, easily realizes.

Claims (5)

1. the Direct Torque Control for the monolateral matrix converter of DC brushless motor, it is characterised in that: at list In the case of the outfan of limit matrix converter is connected with DC brushless motor, carry out Direct Torque Control in the following ways:

1) three-phase voltage of monolateral matrix converter input is detected, it is thus achieved that maximum positive voltage V+ and maximum negative voltage V-；

2) the rotor electrical angle of DC brushless motor is detected, it is judged that obtain the sector at rotor electrical angle place；

3) according to the relation between rotor electrical angle and the back-emf obtained by emulation by rotor electrical angle obtain each on the contrary Electromotive force, detection simultaneously obtains each phase current of monolateral matrix converter output, calculates in conjunction with each opposite potential and each phase current and obtains Obtain the actual electromagnetic torque of current time；

4) according to the sector at the rotor electrical angle place of current time, by space voltage vector selection mode to brush DC electricity The selection respectively carrying out mutually in machine being switched on or off controls, and according to turning on actual electromagnetic torque and the stagnant ring of its torque reference of phase Between relation apply voltage, formed to torque directly control.

The Direct Torque Control side of a kind of monolateral matrix converter for DC brushless motor the most according to claim 1 Method, it is characterised in that: described step 4) according to conducting phase actual electromagnetic torque and the stagnant ring of its torque reference between relation Apply voltage specifically:

Under current time, for turning on biphase each phase, if its actual electromagnetic torque is less than its torque reference stagnant ring lower limit, then This conducting is applied maximum positive voltage V+ mutually, its actual electromagnetic torque is not below its torque reference stagnant ring lower limit conducting phase and All non-conduction phases apply V-；

For a conducting arbitrary phase in biphase, if its actual electromagnetic torque is more than its torque reference stagnant ring upper limit, then to institute Have and apply V-mutually.

The Direct Torque Control side of a kind of monolateral matrix converter for DC brushless motor the most according to claim 1 Method, it is characterised in that:

Described space voltage vector selection mode is according to place sector position employing following table selection space voltage vector:

Wherein, V₁～V₅Represent each voltage vector that sector is corresponding；

The conduction mode represented by below table again according to the space voltage vector selected turns on adjacent biphase:

Wherein, A～F phase represents six phases of DC brushless motor respectively, and O represents that conducting, X represent disconnection.

The Direct Torque Control side of a kind of monolateral matrix converter for DC brushless motor the most according to claim 1 Method, it is characterised in that: the half that torque reference is nominal torque in the stagnant ring of described torque reference.

The Direct Torque Control side of a kind of monolateral matrix converter for DC brushless motor the most according to claim 1 Method, it is characterised in that: described actual electromagnetic torque T_emxIt is calculated by below equation:

$T_{emx}=\frac{P_{emx}}{{\mathrm{\ω}}_m}=\frac{e_x{i}_x}{{\mathrm{\ω}}_m},x=a,b,c......$

Wherein, e_x、i_xIt is respectively phase current and opposite potential, ω_mFor mechanical angle speed, P_emxFor phase electromagnetic power, T_emxIt it is a phase Electromagnetic torque.