WO2016050044A1

WO2016050044A1 - Variable-load, variable-frequency control method and controller

Info

Publication number: WO2016050044A1
Application number: PCT/CN2015/076172
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
Also published as: CN104359184B; CN104359184A

Abstract

A variable-load, variable-frequency control method and a controller. The method is applicable in a variable-frequency air conditioner controller. The controller comprises a master control unit (MCU) (3), a direct current bus circuit, and a three-phase inverter circuit (2) connected thereto. The three-phase inverter circuit (2) drives a compressor into work. The MCU (3) generates a PWM wave to drive the three-phase inverter circuit (2) into work. The method comprises: a compressor phase current is detected; when the compressor is operating, a compressor rotor speed is calculated by the MCU (3) on the basis of the compressor phase current, and a carrier frequency of the PWM wave is set on the basis of the compressor rotor speed, where a lower PWM wave carrier frequency is set when the compressor rotor speed is low, and a higher PWM wave carrier frequency is set when the compressor rotor speed is high. The present invention implements dynamic adjustments of PWM wave carrier frequencies during operation, thus implementing optimal carrier control adapted to the driving frequency of the compressor.

Description

Variable carrier frequency frequency conversion control method and controller

Technical field

The present invention relates to the field of home appliance control, and more particularly to a variable carrier frequency conversion 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 variable speed, which can automatically provide the required amount of cold (heat) according to the indoor conditions; when the indoor temperature reaches the desired value, the air conditioner main unit operates at a constant speed that can accurately maintain this temperature, achieving “ It does not stop running, thus ensuring the stability of the 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 the three-phase AC power is obtained by the rectifier circuit, and then the electrolytic capacitor is used to filter and stabilize. Finally, the output voltage and frequency of the inverter circuit are adjustable. The AC drive drives the inverter compressor.

The PWM wave carrier frequency of the variable frequency controller used in the general inverter air conditioner is fixed. Therefore, when the compressor is operated at a lower frequency, the number of carriers in a single electrical cycle is large, and the dynamic loss and electromagnetic (EMC) interference are compared. Large; when the compressor is running at a higher frequency, the number of carriers in a single electrical cycle is small, resulting in poor modulation effect when PWM wave is used for pulse width modulation, resulting in more severe high frequency vibration caused by poor driving. .

When the air conditioner is cooled, the compressor operates at a lower frequency, and the compressor operates at a higher frequency during heating. At present, a carrier control method is used: a lower PWM wave carrier frequency is used for the cooling operation, and a heating carrier is used for the heating operation. The high PWM wave carrier frequency, but the PWM wave carrier frequency is fixed before the compressor starts running. The PWM wave carrier frequency adjustment cannot be performed during the operation, and the application effect is poor.

Summary of the invention

The present invention aims to solve the above technical problems at least to some extent.

The primary object of the present invention is a variable carrier frequency conversion control method for realizing PWM wave carrier frequency dynamic adjustment, and achieving optimal carrier control compatible with the compressor driving frequency.

It is a further object of the present invention to provide a controller that implements a variable carrier frequency conversion control method.

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

A variable carrier frequency frequency conversion control method is applied to an inverter air conditioner controller, wherein the controller comprises a main control MCU, a DC bus circuit and a three-phase inverter circuit connected thereto, and the three-phase inverter circuit drives the compressor Working, the master MCU generates a PWM wave to drive the three-phase inverter circuit, and the method includes:

Detecting the compressor phase current;

During the operation of the compressor, the master MCU calculates the compressor rotor speed based on the compressor phase current, and sets the carrier frequency of the PWM wave according to the compressor rotor speed. When the compressor rotor speed is low, the setting is lower. The PWM wave carrier frequency sets a higher PWM wave carrier frequency when the compressor rotor speed is higher.

The variable carrier frequency conversion control method of the invention sets the PWM wave carrier frequency according to the speed of the compressor rotor during operation, and sets a lower PWM wave carrier frequency when the compressor rotor speed is lower, when the compressor rotor speed is higher. When high, the higher PWM wave carrier frequency is set, and the dynamic adjustment of the PWM wave carrier frequency during operation is realized, thereby achieving the optimal carrier control compatible with the compressor drive frequency; the lower load is adopted in the low frequency band. Frequency, reduce dynamic loss and EMC interference, adopt high carrier frequency in high frequency band, realize more carrier cycle in single motor drive electronic cycle, achieve better driving PWM wave modulation effect, reduce high frequency operation Mechanical vibration generated by the drive.

In a preferred embodiment, the compressor rotor speed is divided into n intervals, n is a positive integer, and the master MCU sets the PWM wave carrier frequency according to the interval in which the compressor rotor speed is located.

In a preferred embodiment, the specific method of calculating the rotor speed of the compressor is:

Detecting the two-phase currents i _u and i _{v of the} compressor, calculating the third-phase current i _w by using the relationship between the vector sum of the three-phase currents and zero; estimating the rotor position of the compressor based on the three-phase currents i _u , i _v , i _w θ _e , the compressor rotor position θ _e is obtained to obtain the compressor rotor speed ω _e .

In a preferred solution, the method further includes calculating a duty ratio of the PWM wave, and the specific method includes the following steps:

S1: The three-phase currents i _u, i _v, i _w binding rotor position [theta] e, the d axis current d_q rotating coordinate system obtained through coordinate transformation value I _d, the q-axis current value I _q;

S2: the difference between the compressor rotor speed ω _e and its preset reference command value ω _ref passes through a hysteresis PI control link to obtain a reference command value i _{qref of the} q-axis current; i _d and its preset reference command value i _dref The difference is obtained through a hysteresis PI control link, and the d-axis current control command value i _{d1 is obtained} ; the difference between i _q and its preset reference command value i _qref is passed through a hysteresis PI control link to obtain the q-axis current control command value. i _q1 ;

S3: detecting the DC bus voltage value V _p , obtaining a transformation from the d_q rotation coordinate axis to the stator α_β coordinate axis according to i _d1 , i _q1 , θ _e and V _p , obtaining i _α and i _β vectors, and further obtaining the calculation by calculation The required PWM wave duty cycle.

In a preferred solution, the method further includes:

According to the compressor rotor speed ω _e and the preset ω _e , i _d , i _q hysteresis PI controlled coefficient library, the coefficients of hysteresis PI control of ω _e , i _d , i _q are set.

In a preferred solution, the predetermined ω _e , i _d , i _q hysteresis PI controlled coefficient library will be located in different sections of the compressor rotor speed corresponding to different groups of ω _e , i _d , i _q hysteresis The coefficient of PI control.

A variable carrier frequency frequency conversion controller comprises a main control MCU, a DC bus circuit and a three-phase inverter circuit connected thereto, the three-phase inverter circuit drives the compressor, and the main control MCU comprises: a compressor rotor speed calculation unit and a PWM wave a carrier frequency setting unit, a PWM generator, an inverter driving unit, a compressor rotor speed calculating unit detecting a compressor three-phase current and calculating a compressor rotor speed according to the compressor three-phase current and outputting to the PWM wave carrier frequency setting unit, The PWM wave carrier frequency setting unit sets the PWM wave carrier frequency according to the compressor rotor speed and outputs it to the PWM generator. The PWM generator generates a PWM wave according to the PWM wave carrier frequency and transmits it to the inverter driving unit, and the inverter driving unit drives the third. Phase inverter circuit.

The variable carrier frequency conversion controller of the invention realizes the above-mentioned variable carrier frequency frequency conversion control device, and the variable carrier frequency frequency conversion controller of the invention is combined with the above method to realize optimal carrier control adapted to the compressor driving frequency.

In a preferred solution, the master MCU further includes a PWM duty cycle calculation unit, and the PWM duty cycle calculation unit is connected to the DC bus voltage detection unit, the compressor phase current detection unit, the compressor rotor speed calculation unit, and the PWM generation. The PWM duty ratio calculation unit calculates the PWM duty ratio according to the phase current, the compressor rotor speed, the compressor rotor speed reference command value, the d-axis current reference command value, the q-axis current reference command value, and the DC bus voltage, and outputs the PWM duty ratio to The PWM generator, the PWM generator generates a PWM wave according to the PWM duty cycle and the PWM wave carrier frequency.

In a preferred embodiment, the compressor rotor speed is divided into n intervals, n is a positive integer, and the PWM wave carrier frequency setting unit sets the carrier frequency of the PWM wave according to the interval in which the compressor rotor speed is located.

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

The variable carrier frequency conversion control method of the invention sets the PWM wave carrier frequency according to the speed of the compressor rotor during operation, and sets a lower PWM wave carrier frequency when the compressor rotor speed is lower, when the compressor rotor speed is higher. When high, the higher PWM wave carrier frequency is set, and the dynamic adjustment of the PWM wave carrier frequency during operation is realized, thereby achieving the optimal carrier control suitable for the compressor driving frequency;

The variable carrier frequency conversion control method of the invention adopts a lower carrier frequency in a low frequency band, reduces dynamic loss and EMC interference, and adopts a higher carrier frequency in a high frequency band, thereby realizing that there are more internal electronic driving cycles in a single motor. The carrier cycle achieves better driving PWM wave modulation effect and reduces mechanical vibration generated by driving during high frequency operation;

DRAWINGS

1 is a structural diagram of a variable carrier frequency conversion controller according to the present invention.

11, PWM generator; 12, inverter drive unit; 13, PWM wave carrier frequency setting unit; 14, K _p , K _i coefficient library 14; 15, speed / position estimation unit.

detailed description

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

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

Detecting the compressor phase current;

The variable carrier frequency conversion control method of the embodiment sets the PWM wave carrier frequency according to the speed of the compressor rotor during operation, and sets the lower PWM wave carrier frequency when the compressor rotor speed is lower, when the compressor rotor When the speed is high, the higher PWM wave carrier frequency is set, and the dynamic adjustment of the PWM wave carrier frequency during the operation is realized, thereby achieving the optimal carrier control suitable for the compressor driving frequency;

The variable carrier frequency frequency conversion control method of the embodiment adopts a lower carrier frequency in a low frequency band, reduces dynamic loss and EMC interference, and adopts a higher carrier frequency in a high frequency band, thereby realizing more internal driving electron cycles in a single motor. The carrier cycle achieves better driving PWM wave modulation effect and reduces the mechanical vibration generated by the drive during high frequency operation.

Example 2

In the present embodiment, the section of the compressor rotor speed is set based on the first embodiment, and the PWM wave carrier frequency is set based on this.

In a specific implementation process, the specific method for calculating the rotor speed of the compressor is:

Detecting the two-phase current i _u , i _{v of the} compressor, calculating the third phase current i _w by using the vector sum of the three-phase current and zero; estimating the rotor position of the compressor based on the three-phase currents i _u , i _v , i _w θ _e , the compressor rotor position θ _e is obtained to obtain the compressor rotor speed ω _e .

In a specific implementation, the method further includes calculating a duty ratio of the PWM wave, and the specific method includes the following steps:

In a specific implementation process, the method further includes:

According to the compressor rotor speed ω _e and the preset ω _e , i _d , i _q hysteresis PI control coefficient library, the coefficients of hysteresis PI control of ω _e , i _d , i _q are set in the coefficient library. Different hysteresis PI control coefficients are set for different compressor rotor speeds, which facilitates the quick and batch setting of the hysteresis PI control coefficients, improves the efficiency, and makes the PWM wave carrier frequency always optimal. .

In a specific implementation process, the preset ω _e , i _d , i _q hysteresis PI controlled coefficient library will correspond to different groups of compressor rotor speeds corresponding to different groups of ω _e , i _d , i _q hysteresis PI The coefficient of control.

In a specific implementation process, further, the compressor rotor is a two-pole motor, so the compressor rotor speed should be multiplied by two, and the compressor rotor speed is divided into six sections: [20 Hz, 80 Hz), [80 Hz , 100Hz), [100Hz, 120Hz), [120Hz, 160Hz), [160Hz, 200Hz), [200Hz, 240Hz], the compressor rotor speed of 6 sections corresponds to 6 PWM wave carrier frequencies: f1=4kHz, f2= 4.8 kHz, f3 = 5.6 kHz, f4 = 6.5 kHz, f5 = 7.5 kHz, f6 = 9 kHz, thereby adjusting the PWM carrier frequency ratio to keep it always optimal.

In the specific implementation process, further, the compressor rotor speed of the six sections corresponds to the K _p and K _i coefficients of the hysteresis PI control of the six groups of ω _e , i _d , i _{q , and the} hysteresis PI control coefficient of i _d is: The hysteresis PI control coefficients of K _p11 /K _i11 , K _p12 /K _i12 ,..., K _p16 /K _i16 ,i _q are: K _p21 /K _i21 , K _p22 /K _i22 ,...,K _p26 /K The hysteresis PI control coefficients of _i26 and ω _e are: K _p31 /K _i31 , K _p32 /K _i32 , ..., K _p36 /K _i36 , and different ω _e , i are set for the rotor speed of the compressor in different intervals. _d , i _q hysteresis PI controlled K _p , K _i coefficient, thus adjusting the PWM wave duty cycle to always be optimal.

Example 3

In order to solve the system problem caused by frequent switching of the compressor rotor speed at the boundary position of the interval, the present embodiment adopts a backlash control strategy for the boundary of the adjacent interval on the basis of the second embodiment: the compressor rotor speed is rising. When, according to normal operation, when the compressor rotor speed is in the falling phase, the running frequency increases by 6 Hz, that is, the rotor speed of the compressor participating in the judgment is subtracted by 6 Hz, and then the K _p and K _i coefficients of the corresponding group are enabled, which can be effective. Avoid frequent switching problems of K _p and K _i coefficients when the compressor rotor speed is repeatedly changed between different groups.

Example 4

In the embodiment, the basis of the third embodiment is that in the interval 1 and the interval 6 of the rotor speed of the compressor, two sets of K _p and K _i parameters are respectively used to further increase the K _p and K _i coefficients at i _d , i _{q .} , ω _e error in the calculation process, to achieve better PI regulation performance. The setting method is as follows: the interval [20 Hz, 80 Hz) is divided into two groups [20 Hz, 50 Hz) and [50 Hz, 80 Hz), [20 Hz, 50 Hz) corresponding i _d , i _q , ω _e hysteresis PI control link coefficients respectively For the k _p111 /K _i111 , K _p211 /K _i211 , K _p311 /K _i311 ;[50Hz,80Hz), the i _d , i _q , ω _e hysteresis PI control link coefficients are K _p121 /K _i121 , K _p221 /K _i221 , K _p321 /K _i321 .

The interval [200Hz, 240Hz) is also divided into two groups [200Hz, 220Hz) and [220Hz, 240Hz), [200Hz , 220Hz) corresponding to i _d, i _q, ω _e hysteresis loop PI control link coefficients of _K p116 / K _i116 , K _p216 /K _i216 , K _p316 /K _i316 ;[220Hz,240Hz) corresponding i _d , i _q , ω _e hysteresis PI control link coefficients are K _p126 /K _i126 , K _p226 /K _i226 , K _p326 /K _i326 .

Example 5

As shown in FIG. 1 , a variable carrier frequency conversion controller includes a main control MCU, a DC bus circuit, and a three-phase inverter circuit connected thereto, and a three-phase inverter circuit drives the compressor, and the main control MCU includes: a compressor rotor. The speed calculation unit, the PWM wave carrier frequency setting unit 13, the PWM generator 11, the inverter drive unit 12, the compressor rotor speed calculation unit detects the compressor three-phase current and calculates the compressor rotor speed based on the compressor three-phase current and outputs To the PWM wave carrier frequency setting unit 13, the PWM wave carrier frequency setting unit 13 sets the PWM wave carrier frequency according to the compressor rotor speed and outputs it to the PWM generator 11, which is based on the PWM wave carrier. The PWM wave is generated and transmitted to the inverter driving unit 12, and the inverter driving unit 12 drives the three-phase inverter circuit.

The variable carrier frequency conversion controller of the embodiment is the variable carrier frequency conversion control device according to the embodiment 1-4, and the variable carrier frequency conversion controller of the invention is combined with the above method to realize the most suitable for the compressor driving frequency. Good carrier control.

In a specific implementation process, the main control MCU further includes a PWM duty ratio calculation unit, and the PWM duty ratio calculation unit is connected to the DC bus voltage detection unit, the compressor phase current detection unit, the compressor rotor speed calculation unit, and the PWM generator. 11, PWM duty cycle calculation unit according to phase current, compressor rotor speed, preset compressor rotor speed reference command value, preset d-axis current reference command value, preset q-axis current reference command value, DC bus The voltage calculates the PWM duty ratio and outputs it to the PWM generator 11, which generates a PWM wave based on the PWM duty ratio and the PWM wave carrier frequency.

In a specific implementation process, the compressor rotor speed is divided into n intervals, n is a positive integer, and the PWM wave carrier frequency setting unit 13 sets the carrier frequency of the PWM wave according to the interval in which the compressor rotor speed is located.

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

The terms used to describe the positional relationship in the drawings are for illustrative purposes only and are 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 variable carrier frequency frequency conversion control method is applied to an inverter air conditioner controller, wherein the controller comprises a main control MCU, a DC bus circuit and a three-phase inverter circuit connected thereto, and the three-phase inverter circuit drives the compressor Working, the master MCU generates a PWM wave to drive the three-phase inverter circuit, wherein the method comprises:

Detecting the compressor phase current;

During the operation of the compressor, the master MCU calculates the compressor rotor speed based on the compressor phase current, and sets the carrier frequency of the PWM wave according to the compressor rotor speed. When the compressor rotor speed is low, the setting is lower. The PWM wave carrier frequency sets a higher PWM wave carrier frequency when the compressor rotor speed is higher.
The variable carrier frequency conversion control method according to claim 1, wherein the compressor rotor speed is divided into n intervals, n is a positive integer, and the master MCU sets the PWM according to the interval in which the compressor rotor speed is located. Wave carrier frequency.
The variable carrier frequency conversion control method according to claim 1, wherein the specific method of calculating the rotor speed of the compressor is:

Detecting the two-phase current i u , i v of the compressor, calculating the third phase current i w by using the vector sum of the three-phase current and zero; estimating the rotor position of the compressor based on the three-phase currents i u , i v , i w θ e , the compressor rotor position θ e is obtained to obtain the compressor rotor speed ω e .
The variable carrier frequency conversion control method according to claim 3, wherein the method further comprises calculating a duty ratio of the PWM wave, and the specific method comprises the following steps:

S1: The three-phase currents i u, i v, i w binding rotor position [theta] e, the d axis current d_q rotating coordinate system obtained through coordinate transformation value I d, the q-axis current value I q;

S2: the difference between the compressor rotor speed ω e and its preset reference command value ω ref passes through a hysteresis PI control link to obtain a reference command value i qref of the q-axis current; i d and its preset reference command value i dref The difference is obtained through a hysteresis PI control link, and the d-axis current control command value i d1 is obtained ; the difference between i q and its preset reference command value i qref is passed through a hysteresis PI control link to obtain the q-axis current control command value. i q1 ;

S3: detecting the DC bus voltage value V p , obtaining a transformation from the d_q rotation coordinate axis to the stator α_β coordinate axis according to i d1 , i q1 , θ e and V p , obtaining i α and i β vectors, and further obtaining the calculation by calculation The required PWM wave duty cycle.
The variable carrier frequency conversion control method according to claim 4, wherein the method further include:

According to the compressor rotor speed ω e and the preset ω e , i d , i q hysteresis PI controlled coefficient library, the coefficients of hysteresis PI control of ω e , i d , i q are set.
The variable carrier frequency conversion control method according to claim 5, wherein the predetermined ω e , i d , i q hysteresis PI controlled coefficient library corresponds to different groups of compressor rotor speeds corresponding to different groups The coefficient of hysteresis PI control of ω e , i d , i q .
A variable carrier frequency frequency conversion controller comprises a main control MCU, a DC bus circuit and a three-phase inverter circuit connected thereto, and a three-phase inverter circuit drives the compressor, wherein the main control MCU comprises: a compressor rotor speed calculation Unit, PWM wave carrier frequency setting unit, PWM generator, inverter drive unit, compressor rotor speed calculation unit detects compressor three-phase current and calculates compressor rotor speed according to compressor three-phase current and outputs to PWM wave carrier frequency The setting unit, the PWM wave carrier frequency setting unit sets the PWM wave carrier frequency according to the compressor rotor speed and outputs it to the PWM generator, and the PWM generator generates a PWM wave according to the PWM wave carrier frequency and transmits it to the inverter driving unit, and inverts The drive unit drives a three-phase inverter circuit.
The variable carrier frequency conversion controller according to claim 7, wherein the master MCU further comprises a PWM duty cycle calculation unit, the PWM duty cycle calculation unit is connected to the DC bus voltage detection unit, and the compressor phase current detection Unit, compressor rotor speed calculation unit and PWM generator, PWM duty cycle calculation unit according to phase current, compressor rotor speed, compressor rotor speed reference command value, d-axis current reference command value, q-axis current reference command value, The DC bus voltage calculates the PWM duty cycle and outputs it to the PWM generator. The PWM generator generates a PWM wave based on the PWM duty cycle and the PWM wave carrier frequency.
The variable carrier frequency conversion controller according to claim 7, wherein said compressor rotor speed is divided into n intervals, n is a positive integer, and the PWM wave carrier frequency setting unit is located according to a compressor rotor speed The carrier frequency of the PWM wave is set in the interval.