WO2016050047A1

WO2016050047A1 - Single-phase variable-frequency air conditioner control method and controller

Info

Publication number: WO2016050047A1
Application number: PCT/CN2015/076199
Authority: WO
Inventors: 王斌
Original assignee: 海信科龙电器股份有限公司; 广东科龙空调器有限公司
Priority date: 2014-09-30
Filing date: 2015-04-09
Publication date: 2016-04-07

Abstract

A single-phase variable-frequency air conditioner control method, which employs an FOC magnetic field-oriented vector control algorithm to serve as a three-phase inverter drive algorithm. The method comprises: acquiring a target compressor rotational speed and detecting a voltage value of a single-phase alternating current; extracting an alternating current voltage phase on the basis of the voltage value of the alternating current; determining a q-shaft current target value on the basis of the alternating current voltage phase and of the target compressor rotational speed, and participating in an FOC magnetic field-oriented vector control algorithm, where the determined q-shaft current target value is associated with the single-phase alternating current to adjust the output power of a compressor driver, thus allowing the output power to change in a same phase with the voltage of the single-phase alternating current. Also disclosed is a single-phase variable-frequency air conditioner controller. The single-phase variable-frequency air conditioner controller allows costs of a variable-frequency air conditioner to be reduced and circuit power factor to be increased.

Description

Single-phase inverter air conditioner control method and controller

Technical field

The invention relates to the field of inverter air conditioners, and more particularly to a single-phase inverter air conditioner control method and controller.

Background technique

The inverter air conditioner is a special compressor for frequency conversion based on the ordinary air conditioner, and the frequency conversion control system is added. The main unit of the inverter air conditioner is automatically steplessly variable, which can automatically provide the required amount of cold (heat) according to the indoor situation; when the indoor temperature reaches the desired value, the air conditioner main unit operates at a constant speed that can accurately maintain this temperature. Achieve "no downtime" to ensure stable ambient temperature.

In the prior art, the variable frequency control system is generally referred to as a variable frequency controller. The frequency converter is usually a frequency converter of "AC-DC-AC" circuit structure. Its working principle is that single-phase AC power is obtained through the rectifier circuit to obtain DC power, and then the electrolytic capacitor is filtered and stabilized. Finally, the output voltage and frequency of the inverter circuit are adjustable. The AC drive drives the inverter compressor. On the one hand, the electrolytic capacitors used on the one hand have larger capacity and higher cost. On the other hand, the rectifying circuit adopts a single-phase uncontrolled rectification circuit scheme, and the power factor is low and the harmonic currents of three or more times are relatively high, or The active power factor correction circuit scheme is adopted, and although the above problems are solved, the loss is large, the interference is large, and the cost is high.

Summary of the invention

The present invention provides a low-cost, high-power single-phase inverter air conditioner controller in order to overcome at least one of the above-mentioned drawbacks (deficiencies) of the prior art.

In order to solve the above technical problem, the technical solution of the present invention is as follows:

A single-phase inverter air conditioner control method, which adopts a FOC field oriented vector control algorithm as a three-phase inverter driving algorithm, and the method includes:

Obtaining the target speed of the compressor and detecting the voltage value of the single-phase alternating current;

Extracting the phase of the alternating current voltage according to the voltage value of the single-phase alternating current;

The q-axis current target value is determined according to the alternating current voltage phase and the compressor target rotational speed, and participates in the FOC magnetic field oriented vector control algorithm, wherein the determined q-axis current target value is associated with the single-phase alternating current to adjust the output power of the compressor driver. The output power is changed in phase with the single-phase AC voltage.

In the present invention, the q-axis current target value is determined by the phase of the single-phase voltage and the target speed of the compressor, and the q-axis current target value is associated with the single-phase power source, whereby the determined q-axis current target value participates in the FOC magnetic field. In the directional vector control algorithm, since the output power of the compressor is proportional to the q-axis current iq, the output power of the compressor driver is adjusted by determining the target value of the q-axis current so that the output power thereof changes in phase with the AC input voltage, which makes When the AC input voltage is maximum, the output power is maximized, thereby increasing the power factor, and the capacitance of the storage capacitor can be significantly reduced, and the active PFC circuit can be eliminated, thereby improving the conversion efficiency of the controller.

Among them, the FOC field oriented vector control algorithm is a commonly used three-phase motor control algorithm, the basic principle is described as follows:

The phase currents iu and iv of the motor M are detected, and iw is obtained by the following formula:

Iw=-iu-iv

After a-b-c static three-coordinate transformation to d-q rotation coordinates, the transformation formula is as follows:

Clark transform: Iα=iu

Iβ=(3) ^-0.5 *(iu+iv)

Parker transform: id=Iα*cos(θe)+Iβ*sin(θe)

Iq=-Iα*sin(θe)+Iβ*cos(θe)

Where θe is the rotor position angle, which is obtained by the speed/position estimating unit using a well-known estimation algorithm, thereby obtaining the current value id of the d-axis and the current value iq of the q-axis of the motor drive current in the dq rotation coordinate, both currents are The DC component converts AC motor control to DC motor control.

The d-axis represents the excitation direction, and the change of the d-axis current can change the flux linkage of the permanent magnet magnetic field, thereby achieving the weak magnetic control, and the change of the q-axis current can affect the driving power of the motor, for the inverter The output power P is expressed as:

P=iq*Uq, where Uq is the voltage on the q-axis and can be obtained by:

Uq=Rs*id+Lq*piq+ω*Ld*id+ω*ψ

Among them: Rs is the motor winding resistance, Lq is the motor q-axis inductance, piq is the differential of the current iq, ω is the motor speed, Ld is the motor d-axis inductance, and ψ is the motor permanent magnet flux linkage.

For convenience of description and calculation, the above single-phase voltage adopts sinusoidal expression, which is not a common cosine expression. Based on the transformation relationship between sine and cosine, it does not affect the correctness of the result.

In order to achieve the purpose of controlling the motor, the target control current value idref of the d-axis current id and the target control current value iqref of the q-axis current iq are set, and the calculation is directly performed as the target value.

It can be seen from the above description that by adjusting the q-axis current iq, the output power P of the inverter can be adjusted, and if the change of the power P is realized, the phase voltage changes. A modulation coefficient Mv is found such that the change of Mv is related to the phase of the single-phase voltage; in the half-power cycle of the commercial power, the output power is maximum at a voltage phase of 90 degrees, and the output power is minimum at a phase of 0 degrees and 180 degrees.

Specifically, the specific steps of determining the q-axis current target value according to the alternating current voltage phase and the compressor target rotational speed are:

In the S1.FOC field oriented vector control algorithm, the q-axis current base target value iqref is determined according to the compressor target rotational speed, and the modulation coefficient value Mv of the q-axis current target value is generated according to the phase of the single-phase voltage;

S2. Multiplying the q-axis current base target value iqref determined in S1 by the modulation coefficient Mv to determine the q-axis current target value iqref.

Mv is set based on alternating current, that is, to construct a function Mv with the phase of the single-phase voltage as an independent variable. Specifically, the present invention detects the voltage value and phase of the input AC power source in real time, and thereby estimates the phase of the power supply voltage. And further, by setting a modulation coefficient associated with the phase of the power supply voltage, thereby canceling the target value of the q-axis current iq in the FOC field oriented vector control algorithm, since the output power of the compressor is proportional to the q-axis current iq, The output power of the compressor driver is adjusted to make the output power and the AC input voltage change in phase. When the power factor is increased, the capacitance of the storage capacitor can be significantly reduced, and the active PFC circuit can be eliminated, and the controller is improved. Conversion efficiency.

Further, the specific steps of generating the modulation coefficient value Mv of the q-axis current target value according to the phase of the single-phase voltage are:

Setting the modulation factor

function

For the built function,

For the AC power supply voltage phase;

Constructed function

The following conditions are met: the output power modulation of the inverter is realized, and the output power changes with the phase. In the half cycle of the commercial power, the output power is maximum at the voltage phase of 90 degrees, at 0 degrees and 180 degrees. The output power is minimal.

Further, the function

a+b=1, a≥0, b≥0, N is a natural number,

It is the phase of the AC power supply voltage.

Further, the weak magnetic control is also included, and the method is:

The i _dref is set according to the magnitude of the DC side voltage instantaneous value Vp, and the control target value i _dref value is adjusted when the actual compressor driving current i _d satisfies the following formula:

(L _q ×i _q ) ² +(L _d ×i _d +ψ) ² =(Vp-k) ² /(3×ω ² ), where k is a constant greater than zero and less than Vp, and Ld is the compressor The d-axis inductance, Lq is the q-axis inductance, ω is the compressor rotation speed, ψ is the compressor rotor flux linkage, i _d is the d-axis current of the compressor, and i _q is the q-axis current of the compressor;

And the adjustment of the i _dref value makes the values of iq, id, Vp, and ω satisfy the following conditions:

(L _q ×i _q ) ² +(L _d ×i _d +ψ) ² ≤(Vp-k) ² /(3×ω ² );

Thereby real-time weak magnetic control is performed and realized.

Further, the method also detects that the main loop current value corrects Mv.

Further, the specific steps of detecting the main loop current value to correct Mv are:

The correction coefficient value M is generated: the rated value of the actual working current I of the main circuit is I ₀ , the preset current values I ₁ , I ₂ , where I ₀ >I ₁ >I ₂ >0;

Correct the Mv value, where the modulation coefficient value before the correction of the q-axis current target value is Mv1:

When I>I ₀ : Mv=(1+m/100)×Mv1, m is a natural number greater than 1,

When I ₁ ≥ I> I ₂ : Mv=1,

When I ₂ ≥ I: Mv = 1 - (1 - n / 100) × Mv1, n is a natural number greater than 1.

A single-phase inverter air conditioner controller, comprising a main control MCU, a rectifier bridge stack, a three-phase inverter circuit, an LC passive filter circuit, an AC real-time voltage detection unit connected to the main control MCU, and a phase current detection signal of the external compressor The main control MCU is input, and the main control MCU is connected with a main loop current detecting circuit, and the main control MCU drives the three-phase inverter circuit through the inverter driving circuit, and the main control MCU adopts the above-mentioned control method for control, single-phase AC power supply and Rectifier bridge stack connection, LC passive filter circuit is connected in rectifier bridge stack and single-phase inverter circuit, or AC power supply is connected with LC passive filter circuit, LC passive filter circuit is connected with three-phase inverter circuit, and rectifier bridge The stack is connected in the LC passive filter circuit;

The sum of the capacitances in the LC passive filter circuit is less than the product of 0.5μF/W and the maximum allowable output power, and the inductance is less than 15mH.

The main loop current detecting circuit and the compressor phase current iU/iV detecting signal of the invention are respectively connected with the main control MCU, and the main control MC drives the inverter circuit through the inverter driving circuit, and the working mode is corresponding to the FOC magnetic field qualitative vector control algorithm. The circuit connection method, but the difference is: the invention is based on the needs of current type control, the capacitance and the inductance are both smaller values, and the sum of the capacitances of the LC passive filter link is less than the product of the maximum allowable output power of 0.5 μF/W, There is no active PFC power factor correction link at the same time. For the current-type control scheme, since the electrolytic capacitor is an energy storage component, it is not conducive to current-type control, so the smaller the value of the capacitance is, the better, but the capacitance is too small, and the load terminal of the inverter inverter has more interference with the grid. The capacitance value needs to be compromised. In the present invention, the sum of the capacitances in the LC passive filter circuit is set to be less than 0.5 μ. The product of F/W and the maximum allowable output power is beneficial to the current type control, and can minimize the interference of the load end of the inverter inverter to the grid, and the reduction of the capacity can also reduce the cost of the circuit. Secondly, the larger the inductance, the better the current-type control effect, but the cost will increase and the power-frequency voltage drop on the inductor will be larger, which will affect the effective output voltage. The inductance value also needs to be compromised. The invention will be LC passive. The inductance in the filter circuit is set to less than 15mH, which meets the compromise requirement.

Further, a damping resistor is connected in series in the LC passive filter circuit. In order to improve the stability of the entire filtering part and the inverting part, a damping resistor is connected in series in the LC passive filtering section for reducing the voltage oscillation amplitude between the circuit composed of the inductor and the capacitor, that is, reducing the single-phase inverter circuit The voltage fluctuation of the power supply can significantly improve the oscillation characteristics of the filter circuit by damping, and significantly reduce the oscillation amplitude. At the same time, combined with the combination of the post-stage inverter drive control algorithm, the voltage oscillation amplitude can be further reduced or even eliminated.

Further, the resistance of the damping resistor is greater than 0.08 ohms.

Further, the LC passive filter circuit uses a π-type LC filter circuit. The filtering effect is better by using the π-type LC filter circuit.

Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

(1) The method of the present invention detects a voltage of a single-phase AC power source in real time, and acquires a phase of a single-phase voltage based on the detected voltage data in real time, and determines a q-axis current target with a phase of the single-phase voltage and a target speed of the compressor. Value, participate in the FOC field oriented vector control algorithm, adjust the output power of the compressor by adjusting the q-axis current target value, so that the output power changes with the voltage phase. In this process, the q-axis current command value in the FOC field oriented vector control algorithm is correlated with the phase of the power supply voltage, thereby adjusting the output power of the compressor driver, so that the output power and the AC input voltage change in phase, thereby improving the power of the control device. Factors, at the same time, the entire control device can be free of PFC circuit, which can effectively improve the power factor and reduce the harmonic current content.

(2) In the conventional technology, the power factor is also low when the inductance and the capacitance are low, and in the control method of the present invention, since the q-axis current command value can be adjusted, the power factor can be improved, and the power factor can be appropriately reduced. The capacitance and inductance in the LC passive filter circuit achieve a relatively balanced value between the power factor and the capacitance and inductance, thereby reducing the cost of the product while ensuring high power factor.

(3) In the controller of the present invention, the main loop current detecting circuit and the compressor phase current iU/iV detecting signal are respectively connected to the main control MCU, and the main control MC drives the inverter circuit through the inverter driving circuit. The method is the circuit connection method corresponding to the FOC magnetic field qualitative vector control algorithm, but the difference is: the invention is based on the need of current type control, the capacitance and the inductance are both smaller values, and the sum of the capacitance of the LC passive filter link is less than 0.5 μF. /W is the product of the highest allowable output power, and there is no active PFC power factor correction. For the current-type control scheme, since the electrolytic capacitor is an energy storage component, it is not conducive to current-type control, so the smaller the value of the capacitance is, the better, but the capacitance is too small, and the load terminal of the inverter inverter has more interference with the grid. The capacitance value needs to be compromised. In the present invention, the sum of the capacitances in the LC passive filter circuit is set to be less than 0.5 μF/W and the product of the maximum allowable output power, which is advantageous for current type control and can be minimized. The load side of the inverter inverter interferes with the grid, and the reduction in capacitance can also reduce the cost of the circuit. Secondly, the larger the inductance, the better the current-type control effect, but the cost will increase and the power-frequency voltage drop on the inductor will be larger, which will affect the effective output voltage. The inductance value also needs to be compromised. The invention will be LC passive. The inductance in the filter circuit is set to less than 15mH, which meets the compromise requirement.

(4) The controller of the present invention has a damping resistor connected in series in the LC passive filter circuit to reduce the voltage oscillation amplitude between the circuit composed of the inductor and the capacitor.

(3) In the controller of the present invention, the LC passive filter circuit can adopt a π-type LC filter circuit, and the π-type LC filter circuit has a better filtering effect, which can improve the control quality of the entire circuit.

DRAWINGS

Figure 1 is a schematic diagram of the principle of a single-phase inverter air conditioner controller.

Figure 2 is a schematic diagram of a principle of a single-phase inverter air conditioner controller with damping.

FIG. 3 is a schematic diagram of a modified principle of a damped single-phase inverter air conditioner controller.

Figure 4 is a schematic diagram of signal direction in a single-phase inverter air conditioner controller.

detailed description

The drawings are for illustrative purposes only and are not to be construed as limiting the invention;

In order to better illustrate the embodiment, some components of the drawings may be omitted, enlarged or reduced, and do not represent the actual product size;

It will be apparent to those skilled in the art that certain known structures and their description may be omitted.

The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

Example 1

As shown in Figure 1, it is an architectural diagram of a single-phase inverter air conditioner controller and compressor connection. Referring to FIG. 1 , a single-phase inverter air conditioner controller includes a main control MCU 6 , a rectifier bridge stack 2 , and a three-phase inverter circuit 6 . LC passive filter circuit, AC voltage detection unit 1 connected to main control MCU6, compressor phase current detection signal iu/iv input to main control MCU6, main control MCU6 connected with current detection circuit 3, main control MCU6 through inverter drive circuit 5 drive three-phase inverter circuit 6 work, the main control MCU6 uses FOC magnetic field oriented vector control algorithm as the three-phase inverter drive algorithm, LC passive filter circuit usually plays the role of filtering, and part of the energy storage function, appropriate buffer power supply mutation Impact on the inverter part of the rear stage.

Taking the above controller as an example, a single-phase inverter air conditioner control method of the present invention adjusts the output power of the variable frequency controller by a compensation method, and the output power thereof is synchronously adjusted following the phase of the input power source to achieve a power factor improvement. purpose. The method is as follows:

S101. Acquire a target speed of the compressor, and detect a voltage value of the single-phase alternating current;

S102. Extracting an alternating current voltage phase according to a voltage value of the single-phase alternating current;

S103. Determine a q-axis current target value according to the alternating current voltage phase and the compressor target rotational speed, and participate in the FOC magnetic field oriented vector control algorithm, wherein the determined q-axis current target value is associated with the single-phase alternating current to adjust the output of the compressor driver Power, so that the output power changes in phase with the single-phase AC voltage.

Wherein, the target speed of the compressor may be set to a constant value or a change value in practical applications. When it is a constant value, the target value of the q-axis current may be determined directly, and the target speed of the compressor may be directly applied, and each time the determination is made. There is no need to regain the compressor target speed.

The AC power detecting unit 1 can be introduced into the controller. As shown in FIG. 1 , the input end of the AC power detecting unit 1 is connected to the AC power source, and the output end thereof is connected to the main control MCU 6 , and the AC voltage detecting unit 1 can detect the AC. The power supply voltage, and then the AC power supply voltage phase can be extracted according to the AC power supply voltage.

Among them, the FOC field oriented vector control algorithm is a commonly used three-phase motor control algorithm, as shown in Figure 4, the basic principle is described as follows:

Iw=-iu-iv

Clark transform: Iα=iu

Iβ=(3) ^-0.5 *(iu+iv)

Parker transform: id=Iα*cos(θe)+Iβ*sin(θe)

Iq=-Iα*sin(θe)+Iβ*cos(θe)

Where θe is the rotor position angle, based on the detected compressor phase currents iu, iv, iw, and the compressor The known parameters of the parameter d-axis inductance Ld, q-axis inductance Lq, back-potential constant, and d-axis voltage, q-axis voltage, etc. are obtained by the speed/position estimating unit using a well-known estimation algorithm.

Thus, the current value d of the d-axis and the current value q of the q-axis of the motor drive current in the d-q rotation coordinate are obtained, and both currents are DC components, and the AC motor control is converted into DC motor control.

The d-axis represents the excitation direction, and the change of the d-axis current can change the flux linkage of the permanent magnet magnetic field, thereby implementing the weak magnetic control, and the change of the q-axis current can affect the driving power of the motor, and the inverter circuit 4 The output power P is expressed as:

P=iq*Uq, where Uq is the voltage on the q-axis and can be obtained by:

Uq=Rs*id+Lq*piq+ω*Ld*id+ω*ψ

Where: Rs is the motor winding resistance, Lq is the motor q-axis inductance,

Piq is the differential of the current iq, ω is the motor speed, is the differential value of the rotor position angle θe, Ld is the motor d-axis inductance, and ψ is the motor permanent magnet flux linkage.

In the specific implementation process, the determination of the q-axis current target value in S103 can be specifically adopted as follows: in the S1031.FOC field oriented vector control algorithm, the q-axis current base target value iqref is determined according to the compressor target rotational speed, and according to the single The phase of the phase voltage generates a modulation coefficient value Mv of the q-axis current target value;

S1032. Multiplying the q-axis current base target value iqref determined in S1031 by the modulation coefficient Mv to determine the q-axis current target value iqref.

The FOC field oriented vector control algorithm is a general term for a magnetic field oriented space vector algorithm. Based on the algorithm, there are dozens of transform algorithm applications. A specific application algorithm is: setting the target control current value idref of the d-axis current id and the target control current value iqref of the q-axis current iq, and directly participating in the calculation as the target value, the steps are as follows:

1) Let idref=0, iqref is determined by the PI link according to the difference between the estimated speed value ωe value and the compressor speed target value ωref value.

2) Subtracting iqref from the q-axis current value iq of the compressor obtained by Clark transform and Parker transformation, and obtaining a new iqref value after a PI link; the idref and the compressor obtained by Clark transform and Parker transformation The d-axis current value id is subtracted, and after a PI link, a new idref value is obtained;

3) Bring the new iqref and idref into the voltage equation: Calculate the d-axis and q-axis voltage control target values Ud, Uq:

Ud=Rs*id+Ld*pid-ωe*Lq*iq

Uq=Rs*id+Lq*piq+ωe*Ld*id+ωe*ψ

Among them: Rs is the motor winding resistance, Ld, Lq is the motor d-axis, q-axis inductance, pid, piq is the differential of current id, iq, ωe is the motor speed, is the differential value of the rotor position angle θe, ψ is the motor permanent magnet Magnetic flux.

4) Bring the control voltage target value Ud value, Uq value, and rotor position angle θe of the d-axis and the q-axis to the next

Equation, calculate the compressor drive three-phase voltage

Target value

among them

Represents the voltage vector of the three phases of the compressor U, V, W

According to the space vector technique according to the above voltage vector value

Get the PWM duty cycle of the single phase voltage.

For convenience of description and calculation, the above three-phase voltage adopts sinusoidal expression, which is not a common cosine expression. Based on the transformation relationship between sine and cosine, it does not affect the correctness of the result.

Based on the example of the foregoing specific application algorithm, referring to FIG. 4, the steps S1031 and S1032 are described in detail below:

(1) Let the d-axis current target value idref=0 in the FOC field oriented vector control algorithm, and the q-axis current target value iqref use the difference between the estimated speed value ωe value and the compressor speed target value ωref value through PI The link is determined;

(2) Multiplying iqref determined in (1) by Mv as the new q-axis current target value iqref, and the new q-axis current target value iqref and the q-axis current value of the compressor obtained by Clark transform and Parker transformation. Iq is subtracted, and a new iqref value is obtained after a PI link; the ddref is subtracted from the d-axis current value Id of the compressor obtained by the Clark transform and the Parker transform, and a new idref is obtained after a PI link. value;

(3) Substituting the new iqref and idref in (2) into the voltage equation, and calculating the d-axis and q-axis voltage control target values Ud, Uq:

Ud=Rs*id+Ld*pid-ωe*Lq*iq

Uq=Rs*id+Lq*piq+ωe*Ld*id+ωe*ψ

Among them: Rs is the motor winding resistance, Ld, Lq is the motor d-axis, q-axis inductance, pid, piq is the differential of current id, iq, ωe is the motor speed, ψ is the motor permanent magnet flux linkage;

(4) Substituting the control voltage target value Ud value, Uq value, and rotor position angle θe of the d-axis and the q-axis into the following equation, and calculating the three-phase voltage of the compressor drive

Target value

among them

Representing the voltage vector of the three phases of the compressor U, V, W;

Using space vector techniques based on the above voltage vector values

Get a single voltage PWM duty cycle.

In the specific implementation process, the generation of the modulation coefficient value Mv may specifically be as follows:

Setting the modulation factor

function

For the built function,

For the AC power supply voltage phase;

Constructed function

In practical applications, functions

The following formula is preferred:

function

a+b=1, a≥0, b≥0, N is a natural number,

It is the phase of the AC power supply voltage.

Based on the above scheme, in the present invention, the target value of the q-axis current iq is adjusted by using the modulation coefficient Mv of the q-axis current, and is associated with the phase of the power source so that the output power varies with the phase: within half of the power-frequency cycle of the commercial power, The output power is maximum when the voltage phase is 90 degrees, and the output power is minimum when the phase is 0 degrees and 180 degrees, thereby improving the power factor, appropriately reducing the capacitance and inductance in the LC passive filter circuit, and making the power factor and the capacitance and inductance. A relatively reasonable value is achieved between the quantities, thereby reducing the cost of the product while ensuring an increase in power factor.

Secondly, the present embodiment further includes a field weakening control, the method is:

(L _q ×i _q ) ² +(L _d ×i _d +ψ) ² =(Vp-k) ² /(3×ω ² ), where k is a constant greater than zero and less than Vp, and Ld is the compressor D-axis inductance, Lq is q-axis inductance, ω is the compressor speed, ψ is the compressor rotor flux, i _d is the d-axis current of the compressor, and i _q is the q-axis current of the compressor; the value of k is In order to avoid the detection error of the Vp value, the controller should enter the field weakening control without entering the field weakening control, and the k value is a reserved deviation voltage value;

(L _q ×i _q ) ² +(L _d ×i _d +ψ) ² ≤(Vp-k) ² /(3×ω ² );

Thereby real-time weak magnetic control is performed and realized.

The DC side voltage instantaneous value Vp can be obtained by the DC voltage detecting unit 4, as shown in FIG. 1, the input end of the DC voltage detecting unit 4 is connected to the LC passive filter circuit, and the output end thereof is connected to the main control MCU 6. The DC side voltage instantaneous value Vp can be detected by the DC voltage detecting unit 4.

In the specific implementation process, in order to improve the compensation effect of the controller in different output power segments, the method also detects that the main loop current value corrects Mv.

The specific corrections are as follows:

When I>I ₀ : Mv=(1+m/100)×Mv1, m is a natural number greater than 1,

When I ₁ ≥ I> I ₂ : Mv=1,

Example 2

Based on Embodiment 1, the present invention also provides a single-phase inverter air conditioner controller. Referring to FIG. 1, a single-phase inverter air conditioner controller includes a main control MCU6, a rectifier bridge stack 2, a three-phase inverter circuit 6, an LC passive filter circuit, and an AC voltage detecting unit connected to the main control MCU6. 1. The phase current detection signal iu/iv of the external compressor is input to the main control MCU6, the main control MCU6 is connected with the current detection circuit 3, and the main control MCU6 drives the three-phase inverter circuit 6 through the inverter drive circuit 5 to operate the single-phase AC power supply. Connected to the rectifier bridge stack 2, the LC passive filter circuit is connected in the rectifier bridge stack 2 and the three-phase inverter circuit 6, and the LC is passive The sum of the capacitances in the filter circuit is less than the product of 0.5μF/W and the maximum allowable output power, and the inductance is less than 15mH.

The current detecting circuit 3 is connected to the main control MCU6, the compressor phase current iu/iv detecting signal is input into the main control MCU6, and the main control MCU6 drives the three-phase inverter circuit 6 through the inverter driving circuit 5, and the working mode is a kind A circuit connection method corresponding to a typical conventional FOC magnetic field qualitative vector control algorithm. However, the difference is that the present invention is based on the need of current type control, and both the capacitance and the inductance adopt a small value, and the sum of the capacitances of the LC passive filter link is less than the product of the maximum allowable output power of 0.5 μF/W, and there is no active PFC. Power factor correction link. For the current-type control scheme, since the electrolytic capacitor is an energy storage component, it is not conducive to current-type control, so the smaller the value of the capacitance is, the better, but the capacitance is too small, and the load terminal of the inverter inverter has more interference with the grid. The capacitance value needs to be compromised. In the present invention, the sum of the capacitances in the LC passive filter circuit is set to be less than 0.5 μF/W and the product of the maximum allowable output power, which is advantageous for current type control and can be minimized. The load side of the inverter inverter interferes with the grid, and the reduction in capacitance can also reduce the cost of the circuit. Secondly, the larger the inductance, the better the current-type control effect, but the cost will increase and the power-frequency voltage drop on the inductor will be larger, which will affect the effective output voltage. The inductance value also needs to be compromised. The invention will be LC passive. The inductance in the filter circuit is set to less than 15mH, which meets the compromise requirement.

In order to improve the stability of the entire filter part and the inverter part, a damping resistor is connected in series in the LC passive filter circuit. As shown in FIG. 2, a damping resistor R1 is connected in series in the LC passive filtering section for reducing the voltage oscillation amplitude between the circuit composed of the inductor and the capacitor, that is, reducing the voltage fluctuation of the power supply of the single-phase inverter circuit. Damping can significantly improve the oscillation characteristics of the filter circuit, significantly reduce the amplitude of the oscillation, and combined with the back-stage inverter drive control algorithm, can further reduce or even eliminate the voltage oscillation amplitude.

Further, the resistance of the damping resistor is greater than 0.08 ohms.

Example 3

Different from Embodiment 2, in this embodiment, the rectifier bridge stack is connected in series in the middle of the LC passive filter link, that is, the AC power source is connected to the LC passive filter circuit, and the LC passive filter circuit is connected to the three-phase inverter circuit, and The rectifier bridge stack is connected in the LC passive filter circuit. According to the working principle of the series circuit, each series unit in the series circuit can change the serial connection order without affecting the overall equivalent circuit function of the series branch, so the rectifier bridge stack 2 can be connected in series in the middle of the LC passive filtering link.

For example, the connection mode of the rectifier bridge stack is changed on the basis of Embodiment 2. As shown in FIG. 3, the rectifier bridge stack 2 is connected in series in the middle of the LC passive filter link, that is, after the capacitor C1 and the inductor L1, the capacitor C2 and the damping. Before the resistor R1.

The same or similar reference numerals correspond to the same or similar parts;

The positional relationship is described in the drawings for illustrative purposes only and is not to be construed as limiting the invention;

It is apparent that the above-described embodiments of the present invention are merely illustrative of the present invention and are not intended to limit the embodiments of the present invention. Other variations or modifications of the various forms may be made by those skilled in the art in light of the above description. There is no need and no way to exhaust all of the implementations. Any modifications, equivalent substitutions and improvements made within the spirit and scope of the invention are intended to be included within the scope of the appended claims.

Claims

A single-phase inverter air conditioner control method, which adopts a FOC field oriented vector control algorithm as a three-phase inverter driving algorithm, characterized in that the method comprises:

Obtaining the target speed of the compressor and detecting the voltage value of the single-phase alternating current;

Extracting the phase of the alternating current voltage according to the voltage value of the single-phase alternating current;

The q-axis current target value is determined according to the alternating current voltage phase and the compressor target rotational speed, and participates in the FOC magnetic field oriented vector control algorithm, wherein the determined q-axis current target value is associated with the single-phase alternating current to adjust the output power of the compressor driver. The output power is changed in phase with the single-phase AC voltage.
The single-phase inverter air conditioner control method according to claim 1, wherein the specific steps of determining the q-axis current target value according to the alternating current voltage phase and the compressor target rotational speed are:

In the S1.FOC field oriented vector control algorithm, the q-axis current base target value iqref is determined according to the compressor target rotational speed, and the modulation coefficient value Mv of the q-axis current target value is generated according to the phase of the single-phase voltage;

S2. Multiplying the q-axis current base target value iqref determined in S1 by the modulation coefficient Mv to determine the q-axis current target value iqref.
The single-phase inverter air conditioner control method according to claim 2, wherein the specific steps of generating the modulation coefficient value Mv of the q-axis current target value based on the phase of the single-phase voltage are:

Setting the modulation factor
function
For the built function,
For the AC power supply voltage phase;

Constructed function
The following conditions are met: the output power modulation of the inverter is realized, and the output power changes with the phase. In the half cycle of the commercial power, the output power is maximum at the voltage phase of 90 degrees, at 0 degrees and 180 degrees. The output power is minimal.
The single-phase inverter air conditioner control method according to claim 3, wherein

function
a+b=1, a≥0, b≥0, N is a natural number,
It is the phase of the AC power supply voltage.
The single-phase inverter air conditioner control method according to claim 1, further comprising a field weakening control, wherein:

The i dref is set according to the magnitude of the DC side voltage instantaneous value Vp, and the control target value i dref value is adjusted when the actual compressor driving current i d satisfies the following formula:

(L q ×i q ) 2 +(L d ×i d +ψ) 2 =(Vp-k) 2 /(3×ω 2 );

Where k is a constant greater than zero and less than Vp, Ld is the d-axis inductance of the compressor, Lq is the q-axis inductance, ω is the compressor speed, ψ is the compressor rotor flux, i d is the d-axis current of the compressor , i q is the q-axis current of the compressor; and the adjustment of the i dref value makes the values of iq, id, Vp, and ω satisfy the following conditions:

(L q ×i q ) 2 +(L d ×i d +ψ) 2 ≤(Vp-k) 2 /(3×ω 2 );

Thereby real-time weak magnetic control is performed and realized.
The single-phase inverter air conditioner control method according to claim 2, wherein the method further detects that the main loop current value corrects Mv.
The single-phase inverter air conditioner control method according to claim 6, wherein the specific steps of detecting the main circuit current value to correct Mv are:

Generating a correction coefficient value M: setting a nominal value of the actual operating current I of the main circuit I 0 , a preset current value I 1 , I 2 , where I 0 >I 1 >I 2 >0;

Correct the Mv value, where the modulation coefficient value before the correction of the q-axis current target value is Mv1:

When I>I 0 : Mv=(1+m/100)×Mv1, m is a natural number greater than 1;

When I 1 ≥ I> I 2 : Mv=1;

When I 2 ≥ I: Mv = 1 - (1 - n / 100) × Mv1, n is a natural number greater than 1.
A single-phase inverter air conditioner controller, comprising a main control MCU, a rectifier bridge stack, a three-phase inverter circuit, an LC passive filter circuit, an AC real-time voltage detection unit connected to the main control MCU, and a phase current detection signal of the external compressor The main control MCU is connected to the main control MCU, and the main control MCU is connected to the main circuit current detection circuit, and the main control MCU drives the three-phase inverter circuit to work through the inverter drive circuit, wherein the main control MCU adopts any one of claims 1-7. The control method is controlled, the single-phase AC power supply is connected with the rectifier bridge stack, the LC passive filter circuit is connected in the rectifier bridge stack and the single-phase inverter circuit, or the AC power source is connected with the LC passive filter circuit, and the LC passive filter circuit is connected. Connected to a three-phase inverter circuit, and the rectifier bridge stack is connected in the LC passive filter circuit;

The sum of the capacitances in the LC passive filter circuit is less than the product of 0.5μF/W and the maximum allowable output power, and the inductance is less than 15mH.
The single-phase inverter air conditioner controller according to claim 8, wherein a damping resistor is connected in series in the LC passive filter circuit.
The single-phase inverter air conditioner controller according to claim 9, wherein the damping resistor has a resistance greater than 0.08 ohms.
The single-phase inverter air conditioner controller according to any one of claims 8 to 10, wherein the LC passive filter circuit uses a π-type LC filter circuit.