CN103904637B - A kind of DC bus-bar voltage ripple compensation method - Google Patents

Abstract

The invention provides a kind of method compensated DC bus-bar voltage ripple, make under the condition that DC bus-bar voltage ripple amplitude is large, compressor still can normally run, and without the need to using large bulk capacitance.The α shaft voltage component U α that the method exports anti-PARK conversion and β shaft voltage component U β compensate respectively calculate and obtain corresponding α axle compensate after component of voltage U α ' and β axle compensate after component of voltage U β ', after then α axle being compensated component of voltage U α ' and β axle compensate after component of voltage U β ' input to SVPWM loop; One is used for revising the fixing constant index of DC bus place closed-loop system, the target output voltage Uref of DC bus place closed-loop system and being the actual output voltage Udc of DC bus place closed-loop system in compensation calculation process.Method of the present invention makes the material cost of control circuit and power consumption greatly reduce, and designer also no longer needs the stressed problem additionally considering control circuit board.

Description

A kind of DC bus-bar voltage ripple compensation method

Technical field

The present invention relates to the ripple compensation method of DC bus-bar voltage in a kind of convertible frequency air-conditioner.

Background technology

As shown in Figure 1, be existing variable frequency air-conditioner controller FOC algorithm principle.In Fig. 1, after anti-PARK conversion, directly enter SVPWM module.In practice, amplitude due to DC bus-bar voltage is fluctuation, and when load becomes heavy, the ripple of busbar voltage will become large, if when DC bus-bar voltage undulating value is greater than certain value, switching tube can be caused to be less than expection in trough ON time, thus to cause that compressor current is given is less than expection.Because controller adopts closed loop feedback to control, in this case, the dynamic tracking accuracy of controller will be deteriorated, and have an opportunity to cause compressor shutdown.

In order to avoid above situation, existing way adds withstand voltage, capacitance and all larger alminium electrolytic condenser of ripple current, the large electrochemical capacitor parallel connection of general selection 1 ~ 3 uses, to guarantee that actual DC bus-bar voltage ripple is in OK range, make press can stable operation under different loads.But this kind of way bring is being increased sharply of cost, therefore traditional frequency conversion air-conditioner controller cost remains high always.In addition; this way due to electric capacity own vol huge and heavy; designer can not ignore the active force situation of this bulky capacitor to circuit board; therefore actual product must be taked corresponding safeguard measure protecting control plate or directly bulky capacitor is placed on circuit board and mounts in air-conditioning, but such way must cause the increase of material cost and assembly cost.

Summary of the invention

The invention provides a kind of method compensated DC bus-bar voltage ripple, make under the condition that DC bus-bar voltage ripple amplitude is large, compressor still can normally run, and the stabilization time of system shortens, and without the need to using large bulk capacitance.

For achieving the above object, the present invention takes following technical scheme:

A kind of DC bus-bar voltage ripple compensation method, after the α shaft voltage component U α export anti-PARK conversion and β shaft voltage component U β compensates calculating respectively and obtains the α axle compensation of correspondence, component of voltage U α ' and β axle compensate rear component of voltage U β ', then rear for the compensation of α axle component of voltage U α ' and β axle are compensated rear component of voltage U β ' and input to SVPWM loop;

After described α axle compensates, component of voltage U α ' and the rear component of voltage U β ' of β axle compensation is calculated by following:

Uα′=kα×Uα<1>

Uβ′=kβ×Uβ<2>

K α, k β are then determined by following formula:

$\mathrm{k\&alpha;}=\left\{\begin{array}{cc}\mathrm{index}\&times;\mathrm{Uref}/\mathrm{Udc}& |\mathrm{k\&alpha;}\&times;\mathrm{U\&alpha;}|<0.5\\ 1& |\mathrm{k\&alpha;}\&times;\mathrm{U\&alpha;}|>0.5\end{array}\right.---<3>$

$\mathrm{k\&beta;}=\left\{\begin{array}{cc}\mathrm{index}\&times;\mathrm{Uref}/\mathrm{Udc}& |\mathrm{k\&beta;}\&times;\mathrm{U\&beta;}|<0.5\\ 1& |\mathrm{k\&beta;}\&times;\mathrm{U\&beta;}|>0.5\end{array}\right.---<4>$

In formula index be one for revising the fixing constant of DC bus place closed-loop system; Uref is the target output voltage of DC bus place closed-loop system, and Udc is the actual output voltage of DC bus place closed-loop system.

The computational process of the inventive method can by completing the programming of single-chip microcomputer.

Method of the present invention by improvement and optimization traditional F OC algorithm, reduces DC bus-bar voltage ripple and to fluctuate the impact caused compressor control, make DC bus-bar voltage ripple when larger, also can guarantee compressor smooth operation.Achieve the way carrying out alternative traditional single or two to three large capacitance alminium electrolytic condenser parallel connections with multiple discrete low-capacitance Capacitance parallel connection, and about now total capacitance of low-capacitance alminium electrolytic condenser only needs the half of large capacitance alminium electrolytic condenser, material cost and the power consumption of control circuit reduce greatly, life, designer also no longer needs the stressed problem additionally considering control circuit board, simplifies exploitation and installment work.

Accompanying drawing explanation

Fig. 1 is the control method schematic diagram of existing permanent magnet DC motor;

Fig. 2 is the application site schematic diagram of embodiment method;

Fig. 3 is the schematic diagram calculation to U α ' in embodiment;

Fig. 4 is the schematic diagram calculation to U β ' in embodiment.

Embodiment

Below in conjunction with drawings and Examples, content of the present invention is described further.

This DC bus-bar voltage ripple compensation method employing software control logic as shown in Figure 2: after the α shaft voltage component U α export anti-PARK conversion and β shaft voltage component U β compensates calculating respectively and obtains the α axle compensation of correspondence, component of voltage U α ' and β axle compensate rear component of voltage U β ', then rear for the compensation of α axle component of voltage U α ' and β axle are compensated rear component of voltage U β ' and input to SVPWM loop;

After α axle compensates, component of voltage U α ' and the rear component of voltage U β ' of β axle compensation is drawn by following account form:

Uα′=kα×Uα<1>

Uβ′=kβ×Uβ<2>

K α, k β are then determined by following formula:

$\mathrm{k\&alpha;}=\left\{\begin{array}{cc}\mathrm{index}\&times;\mathrm{Uref}/\mathrm{Udc}& |\mathrm{k\&alpha;}\&times;\mathrm{U\&alpha;}|<0.5\\ 1& |\mathrm{k\&alpha;}\&times;\mathrm{U\&alpha;}|>0.5\end{array}\right.---<3>$

$\mathrm{k\&beta;}=\left\{\begin{array}{cc}\mathrm{index}\&times;\mathrm{Uref}/\mathrm{Udc}& |\mathrm{k\&beta;}\&times;\mathrm{U\&beta;}|<0.5\\ 1& |\mathrm{k\&beta;}\&times;\mathrm{U\&beta;}|>0.5\end{array}\right.---<4>$

In formula index be one for revising the fixing constant of DC bus place closed-loop system, specifically, if DC bus place closed-loop system is the system for compressor control, then this constant is the different and constant that specifically sets of individuality according to compressor, and this constant is once be set, and generally no longer revises.Uref is the target output voltage of DC bus place closed-loop system, and Udc is the actual output voltage of DC bus place closed-loop system.

The computational process of formula <1> of the present invention to formula <4>, can be realized by setup algorithm program in single-chip microcomputer, the computational process of program as shown in Figure 3 and Figure 4.

Add above for calculate and export α axle compensate after component of voltage U α ' and β axle compensate after after the single-chip microcomputer computing circuit of component of voltage U β ' or application-specific integrated circuit (ASIC), 2 to 3 large bulk capacitances then need not be adopted again to reduce the fluctuation of DC bus-bar voltage ripple, and only need adopt about about 10 small capacitances, and the total capacity value of these small capacitances is only previous half.The overall cost of these small capacitances far below the overall cost of bulky capacitor, and will need not consider the stress influence that these small capacitances produce circuit board.Greatly save material cost and installation cost.

What this specification was enumerated is only better embodiment of the present invention, and all equivalent technologies conversion done under operation principle of the present invention and thinking, are all considered as protection scope of the present invention.

Claims (1)

1. a DC bus-bar voltage ripple compensation method, it is characterized in that: the α shaft voltage component U α that anti-PARK conversion is exported and to the β shaft voltage component U β that anti-PARK conversion exports compensate respectively calculate and obtain corresponding α axle compensate after component of voltage U α ' and β axle compensate after component of voltage U β ', after then α axle being compensated component of voltage U α ' and β axle compensate after component of voltage U β ' input to SVPWM loop;

After described α axle compensates, component of voltage U α ' and the rear component of voltage U β ' of β axle compensation is calculated by following:

Uα′＝kα×Uα<1>

Uβ′＝kβ×Uβ<2>

K α, k β are then determined by following formula:

$k\mathrm{\&alpha;}=\left\{\begin{array}{cc}index\&times;Uref/Udc& |k\mathrm{\&alpha;}\&times;U\mathrm{\&alpha;}|<0.5\\ 1& |k\mathrm{\&alpha;}\&times;U\mathrm{\&alpha;}|>0.5\end{array}\right.---<3>$

$k\mathrm{\&beta;}=\{\begin{array}{cc}index\&times;Uref/Udc& |k\mathrm{\&beta;}\&times;U\mathrm{\&beta;}|<0.5\\ 1& |k\mathrm{\&beta;}\&times;U\mathrm{\&beta;}|>0.5\end{array}---<4>$

In formula index be one for revising the fixing constant of DC bus place closed-loop system; Uref is the target output voltage of DC bus place closed-loop system, and Udc is the actual output voltage of DC bus place closed-loop system.