WO2016029763A1

WO2016029763A1 - Speed adjustment method and speed adjustment device for capacitance operated single-phase induction motor

Info

Publication number: WO2016029763A1
Application number: PCT/CN2015/084978
Authority: WO
Inventors: 刘鑫; 车玉明
Original assignee: 广东美的环境电器制造有限公司; 美的集团股份有限公司
Priority date: 2014-08-26
Filing date: 2015-07-23
Publication date: 2016-03-03
Also published as: CN104868820B; CN104868820A

Abstract

A speed adjustment method and a speed adjustment device for a capacitance operated single-phase induction motor. The speed adjustment method comprises the following steps: calculating a modulation degree demarcation point of over-modulation according to a space voltage vector, and determining an over-modulation range via the modulation degree demarcation point (S1); calculating an amplitude of the space voltage vector and a switching angle corresponding to a modulation degree according to an over-modulation range where the modulation degree is located (S2); decomposing the amplitude of the space voltage vector into a two-phase static reference coordinate system according to the switching angle so as to obtain a two-phase voltage (S3); and controlling a three-phase inverter by outputting a modulation signal according to the two-phase voltage so as to adjust a rotation speed of a single-phase induction motor (S4). The speed adjustment method and the speed adjustment device can achieve frequency-change speed adjustment of a capacitance operated single-phase induction motor, and can arrive at a full range modulation output, with a rotation speed being closer to a given rotation speed.

Description

Speed regulating method and speed regulating device of capacitor running single-phase induction motor

Technical field

The invention belongs to the technical field of electrical appliances, and in particular relates to a speed regulating method and a speed regulating device for a capacitor-operated single-phase induction motor.

Background technique

The stator of the single-phase induction motor includes a main winding and a secondary winding, that is, a starting winding, and the rotor is a cage type. The operation of the single-phase induction motor mainly includes the capacitor start type and the capacitor operation type. The connection circuit of the capacitor-operated single-phase induction motor is shown in Fig. 1. The structure of the capacitor-operated single-phase induction motor M is simple, and the winding W1' and the winding W2 are composed. 'Composition, the phase shifting capacitor C' has a current I1 of the winding W2' that leads the current I1 of the winding W1' by 90 degrees (electrical angle), so that the winding W1' and the winding W2' form a rotating magnetic field F in space, as shown in FIG. It shows that the capacitor running single-phase induction motor M frequency conversion speed regulation is mainly to change the rotation speed ω' of the rotating magnetic field F. The speed regulation methods mainly include: 1. Single-phase H-bridge mode: the connection circuit diagram is shown in Figure 3, in this mode. Next, the single-phase induction motor M has a voltage peak of U _dc /2 and a low voltage utilization rate. 2, single-phase space vector debugging SVPWM (Space Vector Pulse Width Modulation) mode: its spatial voltage vector distribution is shown in Figure 4, in this mode, as shown in Figure 4, the inscribed circle is the maximum modulation The radius is 0.707, and the maximum modulation can only reach 0.707. Full-range modulation is not possible.

Summary of the invention

The present invention aims to solve at least one of the technical problems in the related art to some extent. Therefore, an object of the present invention is to provide a speed control method for a capacitor-operated single-phase induction motor, which can realize frequency conversion speed regulation of a capacitor-operated single-phase induction motor, and can achieve full-range modulation output. The speed is closer to the given speed.

Another embodiment of the present invention provides a speed governing device for a capacitively operated single phase induction motor.

In order to achieve the above object, an embodiment of the present invention provides a speed control method for a capacitor-operated single-phase induction motor, in which a first winding and a second winding of the single-phase induction motor are respectively connected to a three-phase inverter. The three-phase inverter includes three outputs, wherein the first winding is connected between any two of the three outputs, and the second winding is connected to the three outputs Between the output end remaining after connecting the two output ends of the first winding and the output end connected to the two output ends of the first winding, the speed control method comprises the following steps: The spatial voltage vector calculates a modulation degree demarcation point of the modulation, and determines an overmodulation interval by the modulation degree demarcation point; calculates a magnitude of the spatial voltage vector according to the overmodulation interval in which the modulation degree is located, and a switching angle corresponding to the modulation degree Decomposing the amplitude of the spatial voltage vector into a two-phase stationary reference coordinate system according to the switching angle to obtain a two-phase voltage; and outputting the modulated signal to the three-phase inverter according to the two-phase voltage Controls to adjust the single phase induction motor Speed.

According to the embodiment of the present invention, the speed control method of the capacitor-operated single-phase induction motor realizes the frequency conversion speed regulation of the capacitor-operated single-phase induction motor through overmodulation processing, and can output the full range of modulation degree, which can make the single-phase induction motor The speed is closer to the given speed.

In some embodiments of the present invention, the overmodulation interval includes a first overmodulation interval and a second over modulation interval, and a modulation degree of the first overmodulation interval is 0.707<M≤0.7989, the second The degree of modulation of the overmodulation interval is 0.7989 < M ≤ 1.128, where M is the degree of modulation.

Specifically, when the degree of modulation is in the first overmodulation interval, the amplitude of the space voltage vector and the switching angle corresponding to the modulation degree are calculated in the first sector according to the following formula:

Where f(M, α) is the magnitude of the spatial voltage vector, M is the degree of modulation, α is the switching angle, and θ is the spatial angle of the space voltage vector.

In addition, when the modulation degree is in the second overmodulation interval, the amplitude of the spatial voltage vector and the switching angle corresponding to the modulation degree are calculated in the first sector according to the following formula:

Specifically, when the space voltage vector is in the first sector, the amplitude of the space voltage vector is decomposed into a two-phase stationary reference coordinate system according to the switching angle to obtain a two-phase voltage, which specifically includes:

When the degree of modulation is in the first overmodulation region, the magnitude of the spatial voltage vector is decomposed into a two-phase stationary reference coordinate system according to the following formula to obtain a two-phase voltage:

Where u _a is the voltage of the a-axis in the two-phase stationary reference coordinate system (a, b), u _b is the voltage of the b-axis, α is the switching angle corresponding to the modulation degree, and θ is the space voltage vector Space angle.

When the degree of modulation is in the second overmodulation region, the magnitude of the spatial voltage vector is decomposed into a two-phase stationary reference coordinate system according to the following formula to obtain a two-phase voltage:

Further, the controlling the three-phase inverter according to the two-phase static voltage output modulation signal to adjust the rotation speed of the single-phase induction motor includes: outputting a two-phase sine cosine according to the two-phase voltage A PWM (Pulse Width Modulation) signal controls the three-phase inverter to adjust the rotational speed of the single-phase induction motor.

In order to achieve the above object, another embodiment of the present invention provides a speed regulating device for a capacitive operating single-phase induction motor, the speed adjusting device comprising: a three-phase inverter, the three-phase inverter including three An output end, wherein a first winding of the single-phase induction motor is connected between any two of the three output ends, and a second winding of the single-phase induction motor is connected in the three outputs Removing the output terminal remaining after connecting the two output ends of the first winding with any of the two output terminals connected to the first winding; the controller, the controller according to the target space voltage vector Calculating a modulation degree demarcation point of the modulation, and determining an overmodulation interval by the modulation degree demarcation point, calculating a magnitude of the space voltage vector according to the overmodulation interval in which the modulation degree is located, and a switching angle corresponding to the modulation degree, and according to The switching angle decomposes the magnitude of the space voltage vector into a two-phase stationary reference coordinate system to obtain a two-phase voltage, and outputs a modulation signal to the three-phase inverter according to the two-phase static voltage Row control to adjust the speed of single-phase induction motor.

According to the embodiment of the present invention, the speed control device of the capacitor-operated single-phase induction motor is subjected to modulation processing to realize the frequency conversion speed regulation of the capacitor-operated single-phase induction motor, and the full-range modulation output can be performed, which can make the single-phase induction The motor speed is closer to a given speed.

Specifically, the three-phase inverter includes: a U-phase bridge arm, the U-phase bridge arm includes a first IGBT (Insulated Gate Bipolar Transistor) and a second IGBT, wherein the a first end of an IGBT is connected to the controller, a second end of the first IGBT is connected to a first end of a preset power source, and a first end of the second IGBT is connected to the controller, a second end of the second IGBT is connected to the second end of the preset power source, a third end of the second IGBT is connected to a third end of the first IGBT, and a third end of the second IGBT is a first output end between the third ends of the first IGBT; a V-phase bridge arm, the V-phase bridge arm includes a third IGBT and a fourth IGBT, wherein the first end of the third IGBT a controller connection, a second end of the third IGBT is connected to a first end of the preset power source, a first end of the fourth IGBT is connected to the controller, and a second end of the fourth IGBT End with the pre a second end of the fourth IGBT is connected to the third end of the third IGBT, and a third end of the fourth IGBT is connected between the third end of the fourth IGBT and the third end of the third IGBT Having a second output end, one end of the second winding is connected to the first output end, the other end of the second winding is connected to the second output end; a W-phase bridge arm, the W-phase bridge arm A fifth IGBT and a sixth IGBT are included, wherein a first end of the fifth IGBT is connected to the controller, and a second end of the fifth IGBT is connected to a first end of the preset power source, a first end of the sixth IGBT is connected to the controller, a second end of the sixth IGBT is connected to a second end of the preset power source, and a third end of the sixth IGBT is opposite to the fifth IGBT a third end connection, a third output end of the third end of the sixth IGBT and the third end of the fifth IGBT, one end of the first winding of the single-phase induction motor and the second end The output is connected, and the other end of the first winding is connected to the third output.

The overmodulation interval includes a first overmodulation interval and a second overmodulation interval, the modulation degree of the first overmodulation interval is 0.707<M≤0.7989, and the modulation degree of the second overmodulation interval is 0.7989< M ≤ 1.128, where M is the degree of modulation.

Further, the controller is further configured to control the three-phase inverter to adjust a rotation speed of the single-phase induction motor according to the two-phase voltage output two-phase sine and cosine PWM signal.

DRAWINGS

1 is a schematic diagram of circuit connection of a prior art capacitor-operated single-phase induction motor;

2 is a schematic diagram of a synthetic rotating magnetic field of a prior art capacitively operated single-phase induction motor;

3 is a circuit diagram of a prior art speed control method for a capacitor-operated single-phase induction motor;

4 is a schematic diagram of a maximum modulation degree of a speed control method of another capacitor-operated single-phase induction motor of the prior art;

5 is a flow chart of a method of speed control of a capacitor-operated single-phase induction motor according to an embodiment of the present invention;

6 is a schematic diagram showing a phenomenon in which a modulation degree of a capacitor-operated single-phase induction motor exceeds an existing modulation range according to an embodiment of the present invention;

7 is a schematic diagram of an overmodulation section in a speed control method of a capacitor-operated single-phase induction motor according to another embodiment of the present invention;

8 is a schematic diagram of a space voltage vector of a first overmodulation section in a speed control method of a capacitor-operated single-phase induction motor according to still another embodiment of the present invention;

9 is a schematic diagram of a spatial voltage vector of a second overmodulation section in a speed control method of a capacitor-operated single-phase induction motor according to still another embodiment of the present invention;

10 is a schematic diagram showing division of a modulated sector of a two-phase sine and cosine PWM signal according to still another embodiment of the present invention;

11 is a comparison table of duty ratios and sectors of two-phase sine and cosine PWM signal modulation according to still another embodiment of the present invention;

12 is a flow chart showing a method of speeding a capacitor-operated single-phase induction motor according to another embodiment of the present invention;

Figure 13 is a comparison table of rotational speeds of a capacitor-operated single-phase induction motor before and after overmodulation in accordance with an embodiment of the present invention;

Figure 14 is a schematic illustration of a comparison of over-modulation and non-overmodulation current waveforms in accordance with another embodiment of the present invention;

Figure 15 is a block diagram of a speed governing device of a capacitively operated single phase induction motor in accordance with one embodiment of the present invention;

16 is a schematic diagram showing the connection of a three-phase inverter and a winding of a speed regulating device of a capacitor-operated single-phase induction motor according to another embodiment of the present invention.

Reference mark:

The speed governing device 1000, the three-phase inverter 100 and the controller 200, the first IGBT 101 and the second IGBT 102, the third IGBT 103 and the fourth IGBT 104, the fifth IGBT 105 and the sixth IGBT 106.

detailed description

The embodiments of the present invention are described in detail below, and the examples of the embodiments are illustrated in the drawings, wherein the same or similar reference numerals are used to refer to the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the drawings are intended to be illustrative of the invention and are not to be construed as limiting.

A speed control method and a speed control device for a capacitor-operated single-phase induction motor according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

First, the speed control method of the capacitor-operated single-phase induction motor according to the embodiment of the present invention will be described. Wherein, as shown in FIG. 15, the first winding W1 and the second winding W2 of the single-phase induction motor are respectively connected with the three-phase inverter, and the first winding and the second winding are separated by 90 electrical degrees, the three-phase inverter Including three outputs, wherein the first winding W1 is connected between any two of the three output ends, and the second winding W2 is connected in the three outputs to remove the two outputs connected to the first winding W1. The remaining remaining output is connected to any of the two outputs connected to the first winding W1. The rotational speed of the rotating magnetic field is adjusted by controlling the on-off and duty ratio of the IGBT in the three-phase inverter to adjust the output voltages of the first winding W1 and the second winding W2 of the single-phase induction motor.

5 is a flow chart of a method of speeding a capacitively operated single phase induction motor in accordance with one embodiment of the present invention. As shown in FIG. 5, the speed adjustment method includes the following steps:

S1, calculating a modulation degree demarcation point of the overmodulation according to the space voltage vector, and determining an overmodulation interval by the modulation degree demarcation point.

Specifically, the space voltage vector of the single-phase induction motor may exceed the modulation range in a certain sector. As shown in FIG. 6, FIG. 6(1) shows the first winding W1 and the second winding of the single-phase induction motor. Schematic diagram of the voltage waveform of W2, wherein one period corresponds to four sectors, U _a and U _b are voltage waveforms of the first winding W1 and the second winding W2, respectively, and θ is a spatial angle of the voltage vector. Figure 6 (2) is a schematic diagram of the corresponding degree of modulation, wherein the circle inside the dotted line is the modulation degree that can be achieved by the existing speed regulation method, and the maximum adjustable voltage U _max corresponds to the maximum modulation degree of 0.707, and The line portion is the portion outside the modulation range, for example, located in the first sector and the second sector, corresponding to the shaded portion in Fig. 6(1). When the degree of modulation is out of the modulation range, the space voltage vector, such as U _s , actually outputted by the three-phase inverter may be distorted. For this case, the speed regulation method of the embodiment of the invention is processed by overmodulation, for example, from FIG. 6 . It can be seen that within U _max , the degree of modulation can satisfy the requirement, U _max is an inscribed circle, and the amplitude is 0.707. _{Overmodulation is} required to exceed U _max . Due to the integral relationship between the magnetic field and the voltage, the over-modulation can be realized by using the average voltage in one sector. The modulation degree demarcation point of the overmodulation can calculate the fundamental component by the average voltage or Fourier transform. In the embodiment of the present invention, the overmodulation interval includes a first overmodulation interval I and a second overmodulation interval II, wherein, in a symmetric consideration, the first overmodulation interval I selects an inscribed circle of an equivalent circle with a modulation degree M=1 Square, the modulation degree demarcation point is the amplitude of the flux vector, as shown in Fig. 7 (1), according to the equivalent area calculation method, the inscribed square area is equal to 2, and its equivalent circular area = πR ² , and then R can be calculated. =0.7989, that is, the modulation degree of the first overmodulation interval I can reach 0.7989, that is, the modulation degree demarcation point of the first overmodulation interval I. Specifically, the modulation degree of the first overmodulation interval I is 0.707 < M ≤ 0.7989. In addition, the second overmodulation region II selects a circumscribed square with a modulation degree of M=1, as shown in FIG. 7(2). Similarly, according to the equivalent area calculation method, the area of the circumscribed square is 4, and the equivalent circular area= πR ² =4, and then R=1.128 can be calculated, that is, the modulation degree of the second overmodulation region II can reach 1.128, that is, the modulation degree boundary point of the second overmodulation interval II, specifically, the modulation of the second overmodulation interval II The system is 0.7989 < M ≤ 1.128, where M is the degree of modulation.

S2: Calculate the amplitude of the spatial voltage vector and the switching angle corresponding to the modulation degree according to the overmodulation interval in which the modulation degree is located.

Specifically, the modulation degree is obtained according to the V/F (voltage/frequency) curve of the speed control, and when the modulation degree is greater than 0.707 and less than 0.7989, that is, the modulation degree is in the first overmodulation interval I, the switching is calculated in the first overmodulation interval I. Point, as shown in FIG. 8, is a voltage vector diagram of the first overmodulation interval, and the amplitude is obtained by performing Fourier decomposition on the trajectory waveform of the first overmodulation interval I in FIG. 8, for example, in the first sector. When calculating, the amplitude of the space voltage vector and the switching angle corresponding to the degree of modulation are calculated according to the following formula:

Where f(M, α) is the magnitude of the space voltage vector, M is the degree of modulation, α is the switching angle, and θ is the spatial angle of the space voltage vector. In the overmodulation mode, the switching angle α is different, and the formula for calculating the space voltage vector is different. The modulation degree and the spatial angle can be calculated by the formulas (1) and (2) to obtain the switching angle corresponding to the amplitude of the spatial voltage vector and the degree of modulation.

Specifically, when the degree of modulation is greater than 0.7989 and less than 1.128, ie, in the second overmodulation interval II, the switching point is calculated in the second overmodulation interval II, as shown in FIG. 9, as a second embodiment in accordance with an embodiment of the present invention. Schematic diagram of the voltage vector of the overmodulation interval. In the second overmodulation interval II, when the spatial angle of the spatial voltage vector is smaller than the switching angle, the spatial voltage vector is maintained at the breakpoint of the basic vector, the spatial angle is greater than the switching angle, and the spatial voltage vector is returned. The fixed point of the quadrilateral. The amplitude can be obtained by performing Fourier decomposition on the trajectory waveform of the second overmodulation interval II in FIG. 9. For example, in the first sector, the amplitude of the spatial voltage vector and the switching angle corresponding to the modulation degree are calculated according to the following formula. :

Where f(M, α) is the magnitude of the space voltage vector, M is the degree of modulation, α is the switching angle, and θ is the spatial angle of the space voltage vector. It is known that the modulation degree and the spatial angle can be calculated by the equations (3) and (4) to obtain the switching angle corresponding to the amplitude of the spatial voltage vector and the degree of modulation.

S3. Decompose the amplitude of the space voltage vector into a two-phase stationary reference coordinate system according to the switching angle to obtain a two-phase voltage.

Specifically, after the overmodulation switching angle is determined, the spatial voltage vector is decomposed according to the switching angle to a two-phase stationary coordinate system, such as a two-phase stationary reference coordinate system (a, b), that is, the spatial voltage vector is respectively projected to the a-axis and The b-axis is used to obtain a two-phase voltage.

Taking the space voltage vector in the first sector as an example, specifically, when the modulation degree is in the first overmodulation interval I, the amplitude of the space voltage vector is decomposed into two-phase a and b coordinate systems according to the following formula to obtain two Phase voltage:

Where u _a is the voltage of the a-axis in the two-phase stationary reference coordinate system (a, b), u _b is the voltage of the b-axis, α is the switching angle corresponding to the degree of modulation, and θ is the spatial angle of the space voltage vector.

When the degree of modulation is in the second overmodulation region II, the magnitude of the spatial voltage vector is decomposed into a two-phase stationary reference coordinate system according to the following formula to obtain a two-phase voltage:

Where u _a is the voltage of the a-axis in the two-phase stationary reference coordinate system (a, b), u _b is the voltage of the b-axis, α is the switching angle corresponding to the modulation degree, and θ is the spatial angle of the space voltage vector.

S4, controlling the three-phase inverter according to the two-phase voltage output modulation signal to adjust the rotation speed of the single-phase induction motor.

Specifically, for example, the duty ratio of the output modulation signal is calculated according to the obtained two-phase voltage, that is, the duty ratio can be represented by the associated voltage amplitude, and then the on-off of the IGBT of the three-phase inverter is controlled according to the duty ratio, thereby modulating The voltage of the single-phase induction motor and its rotating magnetic field enable the adjustment of the rotational speed of the single-phase induction motor.

Further, the modulation of the space vector of the six basic vectors causes distortion of the phase voltage waveform, and the two-phase sinusoidal PWM signal can be output according to the two-phase voltage to control the three-phase inverter to adjust the rotational speed of the single-phase induction motor. Specifically, as shown in FIG. 10, a schematic diagram of a sector modulated by a two-phase sine-cosine PWM signal, and FIG. 11 is a comparison table of duty ratios and sectors of a two-phase sine and cosine PWM signal obtained from a two-phase voltage. As shown in FIG. 16, the three-phase inverter includes U, V, and W three-phase bridge arms, and each phase bridge arm includes an upper bridge arm IGBT and a lower bridge arm IGBT. For example, the two-phase sinusoidal PWM signal is output according to the two-phase voltage to modulate the on and off of the IGBTs of the phase bridge arms of the three-phase inverter, for example, in the first sector, the duty of the upper arm IGBT of the U-phase bridge arm The ratio is |u _a |+|U _b |, the duty ratio of the lower arm IGBT of the U-phase arm is 1-|u _a |-|U _b |, and the duty ratio of the IGBT of the V-phase upper arm is |U _b |, the duty ratio of the IGBT of the V-phase lower arm is 1-|U _b |, the upper arm IGBT of the W-phase arm is in a normally closed state, and the W-phase lower arm IGBT is in a normally open state. According to the two-phase voltage output two-phase sine and cosine PWM signal obtained as described above, the IGBT of the three-phase inverter is controlled, so that the phase voltage waveform can be made smoother.

The method for controlling the speed of the capacitor-operated single-phase induction motor of the present invention will be described below with reference to a specific embodiment. As shown in FIG. 12, the following steps are included:

S100, calculating a modulation boundary point.

That is, the demarcation point of the first overmodulation interval is calculated as 0.7989, and the demarcation point of the second overmodulation interval is 1.128.

S200: Determine whether the degree of modulation is greater than 0.707.

If the degree of modulation is greater than 0.707, step S400 is performed, otherwise step S300 is performed.

S300, which outputs a two-phase sine and cosine PWM signal for modulation.

S400: Determine whether the degree of modulation is less than or equal to 0.7989.

If it is less than 0.7989, that is, 0.707 < M ≤ 0.7989, step S500 is performed. Otherwise, that is, greater than 0.7989, that is, 0.7989 < M ≤ 1.128, step S600 is performed.

S500, calculating a switching angle corresponding to the amplitude of the space voltage vector and the modulation degree in the first overmodulation interval, and proceeding to step S700.

S600. Calculate a switching angle corresponding to the amplitude of the space voltage vector and the modulation degree in the second overmodulation interval, and proceed to step S700.

S700, calculating a two-phase voltage in the two-phase stationary coordinate system, and proceeding to step S300.

According to the above-described speed regulation method, the speed of the single-phase induction motor can be made closer to a given rotation speed after modulation. For example, a single-phase induction motor with rated voltage of 220V, rated power of 0.37KW and rated speed of 1390RPM is in no-load. In the state, according to the speed control method of the embodiment of the present invention, by comparing the above-mentioned variable frequency variable voltage control, the comparison of the rotational speeds of the single-phase induction motors before and after the overmodulation is as shown in FIG. 13, and it can be seen that the single phase after passing the overmodulation The speed of the induction motor is closer to a given speed. For example, when the given speed is 1380RPM, the modulation degree is 0.92. It is in the second overmodulation interval. Before the overmodulation, the actual speed of the single-phase induction motor is 1260RPM, and the overmodulation is passed. After that, the actual speed of the single-phase induction motor is 1362RPM, which is very close to the given speed. Therefore, the speed regulation method of the embodiment of the invention can realize the frequency conversion speed regulation of the capacitor-operated single-phase induction motor, which can not only make the single-phase induction motor full. The range modulation output, the speed of the single-phase induction motor is closer to the rated value.

In addition, the comparison between the two-phase current waveform during overmodulation using the speed regulation method of the embodiment of the present invention and the two-phase current waveform for overmodulation is as shown in FIG. 14, wherein FIG. 14(1) is not overmodulated. A schematic diagram of a two-phase current waveform, and FIG. 14 (2) is a schematic diagram of a two-phase current waveform using overmodulation. It can be seen that overmodulation can improve phase current and reduce distortion.

According to the embodiment of the present invention, the speed control method of the capacitor-operated single-phase induction motor realizes the frequency conversion speed regulation of the capacitor-operated single-phase induction motor through overmodulation processing, and can output the full range of modulation degree, and the rotation speed of the single-phase induction motor is more Approaching a given speed. In addition, the phase voltage waveform can be made smoother by using a two-phase sine and cosine PWM signal modulation.

A speed governing device for a capacitively operated single-phase induction motor according to another embodiment of the present invention will now be described with reference to the accompanying drawings. Figure 15 is a block diagram of a speed governing device of a capacitively operated single phase induction motor in accordance with one embodiment of the present invention.

As shown in FIG. 15, the speed regulating device 1000 of the capacitor-operated single-phase induction motor according to the embodiment of the present invention includes a three-phase inverter 100 and a controller 200. The three-phase inverter 100 includes three output terminals such as an output terminal a1. , a2 and a3, wherein the first winding W1 of the single-phase induction motor is connected between any two of the three output terminals, as shown in FIG. 15, the first winding W1 is connected to a3 and a2, single phase The second winding W2 of the induction motor is connected to the three output terminals, and the remaining output terminals, such as the output terminal a1 and the two outputs connected to the first winding W1, are output after the two output terminals of the first winding W1 are connected. The end is for example between the outputs a2.

Further, for example, as shown in FIG. 16, the three-phase inverter 100 includes a U-phase bridge arm, a V-phase bridge arm, and a W-phase bridge arm.

The U-phase bridge arm includes a first IGBT 101 and a second IGBT 102. The first IGBT 101 can serve as an upper arm of the U-phase bridge arm, and the second IGBT 102 can serve as a lower arm of the U-phase bridge arm. The first end of the first IGBT 101 1 is connected to the controller 200, the second end 2 of the first IGBT 101 is connected to a first end of the preset power source, for example, the P end, the first end 1 of the second IGBT 102 is connected to the controller 200, and the second end 2 of the second IGBT 102 is Connected to a second end of the preset power supply, such as the N terminal, the third end 3 of the second IGBT 102 is connected to the third end 3 of the first IGBT 101, and the third end 30 of the second IGBT 102 is connected to the third end 3 of the first IGBT 101. There is a first output, for example a1.

The V-phase bridge arm includes a third IGBT 103 and an fourth IGBT 104, wherein the third IGBT 103 can serve as an upper arm of the V-phase bridge arm, and the fourth IGBT 104 can serve as a lower arm of the V-phase bridge arm, and the first end of the third IGBT 103 1 and controller 200 Connected, the second end 2 of the third IGBT 103 is connected to the first end of the preset power source, the first end 1 of the fourth IGBT 104 is connected to the controller 200, and the second end 2 of the fourth IGBT 104 is connected to the second end of the preset power source. Connecting, the third end 3 of the fourth IGBT 104 is connected to the third end 3 of the third IGBT 103, and the third end 3 of the fourth IGBT 104 and the third end 3 of the third IGBT 103 have a second output end such as an output end a2, One end of the second winding W2 is connected to the first output end a1, and the other end of the second winding W2 is connected to the second output end a2.

The W-phase bridge arm includes a fifth IGBT 105 and a sixth IGBT 106, the fifth IGBT can serve as an upper arm of the W-phase bridge arm, and the sixth IGBT 106 can serve as a lower-arm arm of the W-phase bridge arm, and the first end 1 of the fifth IGBT 105 The controller 200 is connected, the second end 2 of the fifth IGBT 105 is connected to the first end of the preset power source, the first end 1 of the sixth IGBT 106 is connected to the controller 200, and the second end 2 of the sixth IGBT 106 is connected to the preset power source. The second end is connected, the third end 3 of the sixth IGBT 106 is connected to the third end 3 of the fifth IGBT 105, and the third end 3 of the sixth IGBT 106 is connected to the third end 3 of the fifth IGBT 105 with a third output, for example, an output. At terminal a3, one end of the first winding W1 of the single-phase induction motor is connected to the second output terminal a2, and the other end of the first winding W1 is connected to the third output terminal, for example, the output terminal a3.

The controller 200 calculates the modulation degree demarcation point of the overmodulation according to the target space voltage vector, and determines the overmodulation interval with the modulation degree demarcation point. Specifically, when the degree of modulation exceeds the modulation range, the space voltage vector actually output by the three-phase inverter 100 may be distorted. In this case, in the speed regulation device 1000 of the embodiment of the invention, the controller 200 performs the method of overmodulation. For example, as can be seen from FIG. 6, within U _max , the degree of modulation can satisfy the requirement, U _max is an inscribed circle, and the amplitude is 0.707. _{Overmodulation is} required to exceed U _max . Due to the integral relationship between the magnetic field and the voltage, the over-modulation can be realized by using the average voltage in one sector. The modulation degree demarcation point of the overmodulation can calculate the fundamental component by the average voltage or Fourier transform. In the embodiment of the present invention, the overmodulation interval includes a first overmodulation interval I and a second overmodulation interval II, wherein, in a symmetric consideration, the first overmodulation interval I selects an inscribed square with a modulation degree of M=1, as shown in the figure. 7(1), according to the method of equivalent area, the controller 200 calculates that the modulation degree of the first overmodulation interval I can reach 0.7989, that is, the modulation degree boundary point of the first overmodulation interval I, specifically, the first The modulation degree of the modulation section I is 0.707 < M ≤ 0.7989. In addition, the second overmodulation region II selects a circumscribed square with a modulation degree of M=1, as shown in FIG. 7(2), and the controller 200 calculates that the modulation degree of the second overmodulation region II can reach 1.128, that is, the second overmodulation interval. The modulation degree demarcation point of II, specifically, the degree of modulation of the second overmodulation interval II is 0.7989 < M ≤ 1.128, where M is the degree of modulation.

Further, the controller 200 calculates the magnitude of the spatial voltage vector and the switching angle corresponding to the modulation degree based on the overmodulation interval in which the degree of modulation is applied. Specifically, the controller 200 obtains the modulation degree according to the voltage frequency curve. When the modulation degree is greater than 0.707 and less than 0.7989, that is, the modulation degree is in the first overmodulation interval I, the controller 200 calculates the switching point in the first overmodulation interval I, as shown in FIG. 8 is a schematic diagram of the voltage vector of the first overmodulation interval, and the amplitude of the trajectory waveform of the first overmodulation interval I in FIG. 8 is obtained by the controller 200, for example, in the first sector. The controller 200 calculates the magnitude of the spatial voltage vector and the switching angle corresponding to the degree of modulation according to the formulas (1) and (2); or, at the degree of modulation When it is greater than 0.7989 and less than 1.128, that is, in the second overmodulation interval II, the controller 200 calculates a switching point in the second overmodulation interval II, as shown in FIG. 9, as a second overmodulation interval according to an embodiment of the present invention. The voltage vector diagram shows that in the second overmodulation interval, when the spatial angle of the space voltage vector is smaller than the switching angle, the space voltage vector is maintained at the breakpoint of the basic vector, the spatial angle is greater than the switching angle, and the spatial voltage vector returns to the fixed point of the quadrilateral. The amplitude of the trajectory waveform of the second overmodulation interval I in FIG. 9 is obtained by the controller 200, for example, in the first sector, the space voltage vector is calculated according to the formulas (3) and (4). The amplitude and the switching angle corresponding to the degree of modulation.

After the overmodulation switching angle is determined, the controller 200 decomposes the amplitude of the spatial voltage vector into a two-phase stationary reference coordinate system according to the switching angle, for example, under the two-phase stationary reference coordinate system (a, b), that is, respectively, the spatial voltage vector is projected. Go to the a and b axes to get the two phase voltage. Taking the spatial voltage vector in the first sector as an example, specifically, when the modulation degree is in the first overmodulation interval I, the controller 200 decomposes the amplitude of the spatial voltage vector to two phases according to formulas (5) and (6). a, b coordinate system to obtain two-phase voltage; or, when the degree of modulation is in the second overmodulation area II, the controller 200 decomposes the amplitude of the spatial voltage vector to two-phase stationary according to formulas (7) and (8) Reference coordinate system to obtain two-phase voltage.

Then, the controller 200 controls the three-phase inverter 100 according to the two-phase static voltage output modulation signal to adjust the rotational speed of the single-phase induction motor. For example, the controller 200 calculates the duty ratio of the output modulation signal according to the obtained two-phase voltage to control the on and off of the IGBT of the three-phase inverter 100, thereby modulating the voltage of the single-phase induction motor and its rotating magnetic field, thereby realizing the single phase. Adjustment of the speed of the induction motor.

Further, the modulation using the space vectors of the six basic vectors causes the waveform distortion of the phase voltage, and the controller 200 is further configured to control the three-phase inverter 100 according to the two-phase voltage output two-phase sine and cosine PWM signals to adjust the single The speed of the phase induction motor. Specifically, as shown in FIG. 10, a schematic diagram of a sector modulated by a two-phase sine-cosine PWM signal, and FIG. 11 is a comparison table of duty ratios and sectors of a two-phase sine and cosine PWM signal obtained from a two-phase voltage. For example, the controller 200 modulates the on and off of the IGBTs of the phase bridge arms of the three-phase inverter 100 according to the two-phase voltage output two-phase sine and cosine PWM signals, for example, the upper arm of the U-phase bridge arm in the first sector. The duty ratio of the IGBT is |u _a |+|U _b |, the duty ratio of the lower arm IGBT of the U-phase arm is 1-|u _a |-|U _b |, and the IGBT of the V-phase upper arm The duty ratio is |U _b |, the duty ratio of the IGBT of the V-phase lower arm is 1-|U _b |, the upper arm IGBT of the W-phase arm is in the normally closed state, and the W-phase lower arm IGBT is in the normal state. Open state. The controller 200 controls the IGBT of the three-phase inverter 100 according to the two-phase voltage output two-phase sine and cosine PWM signals obtained as described above, so that the phase voltage waveform can be made smoother.

According to the embodiment of the present invention, the speed control device of the capacitor-operated single-phase induction motor is subjected to modulation processing to realize the frequency conversion speed regulation of the capacitor-operated single-phase induction motor, and the full-range modulation output can be performed, which can make the single-phase induction The motor speed is closer to a given speed. In addition, the controller outputs a two-phase sine and cosine PWM signal modulation, which makes the phase voltage waveform smoother.

Moreover, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. Or implicitly indicate the number of technical features indicated. Thus, features defining "first" or "second" may include at least one of the features, either explicitly or implicitly. In the description of the present invention, the meaning of "a plurality" is at least two, such as two, three, etc., unless specifically defined otherwise.

In the present invention, the terms "installation", "connected", "connected", "fixed" and the like shall be understood broadly, and may be either a fixed connection or a detachable connection, unless explicitly stated and defined otherwise. , or integrated; can be mechanical or electrical connection; can be directly connected, or indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction of two elements, unless otherwise specified Limited. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood on a case-by-case basis.

In the present invention, the first feature "on" or "under" the second feature may be a direct contact of the first and second features, or the first and second features may be indirectly through an intermediate medium, unless otherwise explicitly stated and defined. contact. Moreover, the first feature "above", "above" and "above" the second feature may be that the first feature is directly above or above the second feature, or merely that the first feature level is higher than the second feature. The first feature "below", "below" and "below" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely that the first feature level is less than the second feature.

In the description of the present specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like means a specific feature described in connection with the embodiment or example. A structure, material or feature is included in at least one embodiment or example of the invention. In the present specification, the schematic representation of the above terms is not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, various embodiments or examples described in the specification, as well as features of various embodiments or examples, may be combined and combined.

Although the embodiments of the present invention have been shown and described, it is understood that the above-described embodiments are illustrative and are not to be construed as limiting the scope of the invention. The embodiments are subject to variations, modifications, substitutions and variations.

Claims

A speed control method for a capacitor-operated single-phase induction motor, characterized in that a first winding and a second winding of the single-phase induction motor are respectively connected with a three-phase inverter, and the three-phase inverter includes three Outputs, wherein the first winding is connected between any two of the three outputs, the second winding is connected in the three outputs to remove the first winding The remaining output end after the two outputs is connected to any one of the two output terminals connected to the first winding, and the speed control method comprises the following steps:

Calculating a modulation degree demarcation point of the overmodulation according to the space voltage vector, and determining an overmodulation interval by using the modulation degree demarcation point;

Calculating a magnitude of the spatial voltage vector and a switching angle corresponding to the modulation degree according to an overmodulation interval in which the modulation degree is located;

Decomposing the magnitude of the spatial voltage vector into a two-phase stationary reference coordinate system according to the switching angle to obtain a two-phase voltage;

The three-phase inverter is controlled to adjust the rotational speed of the single-phase induction motor according to the two-phase voltage output modulation signal.
The method according to claim 1, wherein the overmodulation interval comprises a first overmodulation interval and a second overmodulation interval, and the first overmodulation interval is adjusted. The system is 0.707 < M ≤ 0.7989, and the modulation degree of the second overmodulation interval is 0.7989 < M ≤ 1.128, where M is the degree of modulation.
The method of controlling a variable speed single-phase induction motor according to claim 2, wherein when said modulation degree is in said first overmodulation interval, said space is calculated in said first sector according to the following formula The magnitude of the voltage vector and the switching angle corresponding to the degree of modulation:

Where f(M, α) is the magnitude of the spatial voltage vector, M is the degree of modulation, α is the switching angle, and θ is the spatial angle of the space voltage vector.
The method for controlling a variable speed single-phase induction motor according to claim 2, wherein in the first sector, when the degree of modulation is in the second overmodulation interval, the calculation is performed according to the following formula The magnitude of the spatial voltage vector and the switching angle corresponding to the degree of modulation:

Where f(M, α) is the magnitude of the spatial voltage vector, M is the degree of modulation, α is the switching angle, and θ is the spatial angle of the space voltage vector.
The method for controlling a variable speed single-phase induction motor according to claim 2, wherein when the space voltage vector is in the first sector, the amplitude of the space voltage vector is decomposed according to the switching angle To the two-phase stationary reference coordinate system to obtain two-phase voltage, specifically including:

When the degree of modulation is in the first overmodulation region, the magnitude of the spatial voltage vector is decomposed into a two-phase stationary reference coordinate system according to the following formula to obtain a two-phase voltage:

Where u a is the voltage of the a-axis in the two-phase stationary reference coordinate system (a, b), u b is the voltage of the b-axis, α is the switching angle corresponding to the modulation degree, and θ is the space voltage vector Space angle.
The method for controlling a variable speed single-phase induction motor according to claim 5, further comprising: when said modulation degree is in said second overmodulation zone, said spatial voltage vector according to the following formula The amplitude is decomposed into a two-phase stationary reference coordinate system to obtain a two-phase voltage:

Where u a is the voltage of the a-axis in the two-phase stationary reference coordinate system (a, b), u b is the voltage of the b-axis, α is the switching angle corresponding to the modulation degree, and θ is the space voltage vector Space angle.
The method for controlling a variable speed single-phase induction motor according to claim 1, wherein said controlling said three-phase inverter according to said two-phase static voltage output modulation signal to adjust said single The speed of the phase induction motor includes:

The three-phase inverter is controlled to adjust the rotational speed of the single-phase induction motor according to the two-phase voltage output two-phase sine and cosine PWM signal.
A speed regulating device for a capacitor-operated single-phase induction motor, characterized in that it comprises:

a three-phase inverter comprising three outputs, wherein a first winding of the single-phase induction motor is connected between any two of the three outputs, the single a second winding of the phase induction motor is connected to the three Between the output ends of the output terminals, the remaining output terminals connected to the two output ends of the first winding are connected to any one of the two output terminals connected to the first winding;

a controller, the controller calculates an overmodulation modulation degree demarcation point according to the target space voltage vector, and determines an overmodulation interval by the modulation degree demarcation point, and calculates a magnitude of the space voltage vector according to the overmodulation interval in which the modulation degree is located And a switching angle corresponding to the modulation degree, and decomposing the amplitude of the spatial voltage vector into a two-phase stationary reference coordinate system according to the switching angle to obtain a two-phase voltage, and outputting a modulation signal according to the two-phase static voltage The three-phase inverter is controlled to adjust the rotational speed of the single-phase induction motor.
The speed regulating device for a capacitor-operated single-phase induction motor according to claim 8, wherein the three-phase inverter comprises:

a U-phase bridge arm, the U-phase bridge arm including a first IGBT and a second IGBT, wherein a first end of the first IGBT is connected to the controller, and a second end of the first IGBT is preset a first end of the power source is connected, a first end of the second IGBT is connected to the controller, and a second end of the second IGBT is connected to a second end of the preset power source, the second IGBT The third end is connected to the third end of the first IGBT, and the third end of the second IGBT and the third end of the first IGBT have a first output end;

a V-phase bridge arm, the V-phase bridge arm including a third IGBT and a fourth IGBT, wherein a first end of the third IGBT is connected to the controller, and a second end of the third IGBT is a first end of the predetermined power source is connected, a first end of the fourth IGBT is connected to the controller, and a second end of the fourth IGBT is connected to a second end of the preset power source, the fourth a third end of the IGBT is connected to the third end of the third IGBT, and a third output end is formed between the third end of the fourth IGBT and the third end of the third IGBT, the second winding One end is connected to the first output end, and the other end of the second winding is connected to the second output end;

a W-phase bridge arm, the W-phase bridge arm including a fifth IGBT and a sixth IGBT, wherein a first end of the fifth IGBT is connected to the controller, and a second end of the fifth IGBT is a first end of the preset power source is connected, a first end of the sixth IGBT is connected to the controller, and a second end of the sixth IGBT is connected to a second end of the preset power source, the sixth a third end of the IGBT is connected to the third end of the fifth IGBT, and a third output end is connected between the third end of the sixth IGBT and the third end of the fifth IGBT, the single-phase induction motor One end of the first winding is connected to the second output, and the other end of the first winding is connected to the third output.
The speed regulating device for a capacitor-operated single-phase induction motor according to claim 8, wherein the overmodulation interval comprises a first overmodulation interval and a second overmodulation interval, and the first overmodulation interval is adjusted The system is 0.707 < M ≤ 0.7989, and the modulation degree of the second overmodulation interval is 0.7989 < M ≤ 1.128, where M is the degree of modulation.
The speed regulating device for a capacitor-operated single-phase induction motor according to claim 8, wherein the controller is further configured to output a two-phase sine and cosine PWM signal to the three-phase inverter according to the two-phase voltage Control to adjust The rotational speed of the single phase induction motor.