CN105262397A - Positioning current control method of variable frequency motor - Google Patents

Abstract

The present invention relates to an air conditioning control technology, and discloses a positioning current control method of a variable frequency motor. The positioning current control method solves the problem that in a traditional permanent magnet synchronous DC brushless motor positioning technology, power-on sequence of six IGBTs cannot change so that the IGBTs have different service lives. The positioning current control method comprises the steps of: controlling a d-axis current to change from 0 to a positioning target current Id0, controlling a q-axis current to be 0; controlling a positioning angle theta to be 0 degree when positioning is activated firstly; and controlling the positioning angle theta to change by a constant angle n relative to the previous positioning when every positioning is activated after that. Through adoption of the positioning current control method of the present invention, average conducting time of each IGBT is equal during positioning, thus the service life of the IGBT cannot be affected by the positioning, thereby prolonging the service life of the IGBT, solving the problem that the service lives of the IGBTs are inconsistent in a traditional positioning method, and improving service time of a product, therefore, the positioning current control method is suitable for positioning current control of a variable frequency motor of an air conditioning.

Description

A kind of variable-frequency motor location current control method

Technical field

The present invention relates to air conditioner controlling technology, particularly variable-frequency motor location current control method.

Background technology

Traditional permanent-magnet synchronous DC brushless motor localization method, employing location current controls, location current generally adopts d shaft current to be not equal to 0, and q shaft current is 0 to control, but the space vector direction that location current is formed is fixed, only change the size of location current, angle theta between space vector and fixed coordinates axle α axle is constant, force rotor turns to the direction of current phasor, adopt and locate in this way, each startup can be caused, upper and lower six IGBT power-up sequence can not change, some IGBT (insulated gate bipolar transistor) are long for conduction time, some conduction time is short, the IGBT even had is not energized, long-play, the situation that the IGBT life-span can be caused inconsistent occurs.

As shown in Figure 1, current phasor under decomposing fixed coordinate system u/v/w coordinate, assuming that size is I _{d_0}, then I _{u_0}=I _{d_0}cos θ, I _{v_0}=I _{d_0}cos (θ-120), I _{w_0}=I _{d_0}cos (θ+120), when θ is constant, I _{u_0}/ I _{v_0}/ I _{w_0}size only and I _{d_0}relevant, the sense of current can not change, particularly, when θ=0, visible, during each positioning starting, electric current is fixing flows into motor coil from U phase, and flow out from motor V phase and W coil, cause 6 IGBT, only have IGBTa, IGBTe and IGBTf conducting, other several IGBT not conductings, as shown in Figure 2, this localization method of Long-Time Service, will inevitably cause the IGBT problem generation that useful life, length differed.

Summary of the invention

Technical problem to be solved by this invention is: propose a kind of variable-frequency motor location current control method, solve in traditional permanent-magnet synchronous DC brushless motor location technology, upper and lower six IGBT power-up sequence can not change and cause the IGBT problem that useful life, length differed.

The present invention solves the problems of the technologies described above adopted technical scheme, a kind of variable-frequency motor location current control method, and it comprises: control d shaft current is from 0 to localizing objects electric current I _d0change, control q shaft current is 0, and during initiating switchup location, controlling orientation angle θ is 0 degree; After this, during each positioning starting, orientation angle θ relatively last location change fixed angle n ° is controlled.

Further, the mode of described control orientation angle θ relatively last location change n ° is: controlling the relatively last orientation angle of orientation angle θ increases.

Further, described orientation angle refers to the angle between the space vector direction that d shaft current is formed and fixed coordinates axle α axle.

Further, described n °=60 °.

The invention has the beneficial effects as follows: the average time of every IGBT conducting during location can be made equal, the impact that IGBT is not located useful life, extend the useful life of IGBT, solve conventional mapping methods IGBT life-span inconsistent problem, improve product service time.

Accompanying drawing illustrates:

Fig. 1 is current phasor in conventional art decompose fixed coordinate system u/v/w coordinate schematic diagram;

Fig. 2 is 6 IGBT connection diagrams in conventional art;

Fig. 3 is variable-frequency motor location current control method flow chart of the present invention.

Embodiment

The present invention is intended to propose a kind of variable-frequency motor location current control method, solves in traditional permanent-magnet synchronous DC brushless motor location technology, and upper and lower six IGBT power-up sequence can not change and cause the IGBT problem that useful life, length differed.

As shown in Figure 3, the solution of the present invention comprises: control d shaft current is from 0 to localizing objects electric current I _d0change, control q shaft current is 0, and during initiating switchup location, controlling orientation angle θ is 0 degree; After this, during each positioning starting, orientation angle θ relatively last location change fixed angle n is controlled.

In specific implementation, initiating switchup is located, orientation angle is 0 degree, each startup later, orientation angle adds 60 degree, orientation angle θ comprises 0 °, 60 °, 120 °, 180 °, 240 °, 300 °, like this, when θ=0 °, IGBTa, IGBTe and IGBTf conducting, when θ=60 °, IGBTa, IGBTb and IGBTf conducting, when θ=120 °, IGBTb, IGBTd and IGBTf conducting, when θ=180 °, IGBTb, IGBTc and IGBTd conducting, when θ=240 °, IGBTc, IGBTd and IGBTe conducting, when θ=300 °, IGBTa, IGBTc and IGBTe conducting.

The method of visible this control location current, the average time of every IGBT conducting can be made equal, the impact that IGBT is not located useful life, extend the useful life of IGBT, solve conventional mapping methods IGBT life-span inconsistent problem, improve product service time.

Claims (4)

1. a variable-frequency motor location current control method, is characterized in that, comprising: control d shaft current is from 0 to localizing objects electric current I _d0change, control q shaft current is 0, and during initiating switchup location, controlling orientation angle θ is 0 degree; After this, during each positioning starting, orientation angle θ relatively last location change fixed angle n ° is controlled.

2. a kind of variable-frequency motor location current control method as claimed in claim 1, is characterized in that, the mode of described control orientation angle θ relatively last location change n ° is: controlling the relatively last orientation angle of orientation angle θ increases.

3. a kind of variable-frequency motor location current control method as claimed in claim 1, is characterized in that, described orientation angle refers to the angle between the space vector direction that d shaft current is formed and fixed coordinates axle α axle.

4. a kind of variable-frequency motor location current control method as claimed in claim 1, is characterized in that, described n °=60 °.