阅读说明：本技术 一种异步电机电容自动内补偿控制装置 (Automatic internal compensation control device for asynchronous motor capacitor ) 是由 刘涛 刘建平 温书林 于 2021-09-30 设计创作，主要内容包括：本发明提供一种异步电机电容自动内补偿控制装置,包括定子绕组、主电容器C01-C03、副电容器C04-C06、调节器,定子绕组包括三相主绕组Wa1、Wb1、Wc1和三相副绕组Wa2、Wb2、Wc2,Wa1首端与Wc2末端连接,连接点为A1,Wb1首端与Wa2末端连接,连接点为B1,Wc1首端与Wb2末端连接,连接点为C1,连接点A1、B1、C1通过交流开关K1分别与交流电源端A0、B0、C0连接,主绕组Wa1、Wb1、Wc1的末端分别为连接点A2、B2、C2,副绕组Wa2、Wb2、Wc2的首端分别为连接点A3、B3、C3,连接点A2与C3、B2与A3、B3与C2之间分别连接副电容器C04、C05、C06,主电容器C01-C03与主绕组Wa1、Wb1、Wc1末端连接,调节器与副绕组Wa2、Wb2、Wc2首端连接。本发明利用主电容器对主绕组预先进行电容内补偿,然后用调节器对副绕组进行动态调整,用较小的起动电流完成包括重载设备在内的各类设备起动,并达到功率因数为1.0的效果。(The invention provides an automatic internal compensation control device for asynchronous motor capacitance, which comprises a stator winding, a main capacitor C-C, an auxiliary capacitor C-C and a regulator, wherein the stator winding comprises three-phase main windings Wa, Wb and Wc and three-phase auxiliary windings Wa, Wb and Wc, the head end of Wa is connected with the tail end of Wc, a connection point is A, the head end of Wb is connected with the tail end of Wa, a connection point is B, the head end of Wc is connected with the tail end of Wb, a connection point is C, the connection points A, B and C are respectively connected with alternating current power supply ends A, B and C through an alternating current switch K, the tail ends of the main windings Wa, Wb and Wc are respectively connected with connection points A, B and C, the head ends of the auxiliary windings Wa, Wb and Wc are respectively connected with connection points A, B and C, the auxiliary capacitors C and C are respectively connected between the connection points A, B and C, the auxiliary capacitors C and the tail ends of the main capacitors Wa, Wb and Wc, the regulator is connected with the head ends of the secondary windings Wa2, Wb2 and Wc 2. The invention uses the main capacitor to carry out capacitance internal compensation on the main winding in advance, then uses the regulator to carry out dynamic adjustment on the auxiliary winding, uses smaller starting current to complete the starting of various devices including heavy-load devices, and achieves the effect that the power factor is 1.0.)

1. An automatic internal compensation control device for asynchronous motor capacitor is characterized by comprising a stator winding, an alternating current power supply, a main capacitor C01-C03, an auxiliary capacitor C04-C06, a regulator and an alternating current switch K1,

the stator winding comprises nine connection points of three-phase main windings Wa1, Wb1, Wc1 and three-phase auxiliary windings Wa2, Wb2 and Wc2, the head end of Wa1 is connected with the tail end of Wc2, the connection point is A1, the head end of Wb1 is connected with the tail end of Wa2, the connection point is B1, the head end of Wc1 is connected with the tail end of Wb2, the connection point is C1, three potential phasor V-shaped connections are formed, the tail ends of the main windings Wa1, Wb1 and Wc1 are respectively connection points A2, B2 and C2, the head ends of the auxiliary windings Wa2, Wb2 and Wc2 are respectively connection points A3, B3 and C3, A1, B1, C1, A2, B2, C2, A3, B3 and C3 are led out together to form a basic circuit,

connection points A1, B1 and C1 are respectively connected with alternating current power supply ends A0, B0 and C0 through an alternating current switch K1, auxiliary capacitors C04, C05 and C06 are respectively connected between the connection points A2 and C3, between the connection points B2 and A3 and between the connection points B3 and C2,

the main capacitors C01-C03 are connected with the tail ends of the main windings Wa1, Wb1 and Wc1, the regulators are connected with the head ends of the auxiliary windings Wa2, Wb2 and Wc2, and the voltage and the current of the connection points A3, B3 and C3 are regulated by PWM control.

2. The automatic internal compensation control device for asynchronous motor capacitance according to claim 1, main capacitors C01, C02 and C03 are respectively connected between the stator main winding connection points A2 and C1, between B2 and A1 and between C2 and B1, the regulator comprises three single-phase regulators, a unidirectional regulator is respectively connected between a main winding connection point A1 and A3, between a main winding connection point B1 and B3, and between a C1 and C3, the single-phase regulator comprises a single-phase rectifier bridge consisting of four rectifier tubes D1-D4/D5-D8/D9-D12 and an insulated gate bipolar transistor T1/T2/T3, wherein a direct current positive output end and a direct current negative output end of the single-phase rectifier bridge are respectively connected with a C pole and an E pole of the insulated gate bipolar transistor T1/T2/T3, meanwhile, the direct current positive output end and the direct current negative output end of the single-phase rectifier bridge are respectively connected with the cathode and the anode of the rectifier tube D13/D14/D15.

3. The automatic internal compensation control device for the asynchronous motor capacitor of claim 1 is characterized in that main capacitors C01, C02 and C03 are respectively connected between the stator main winding connection point A2 and C1, B2 and A1, and between C2 and B1, and the turn ratio of the main winding to the auxiliary winding is V3: 1, the voltage phasor of secondary winding is than 30 degrees electrical angle settings in advance of homophase main winding, the regulator is three-phase regulator, three-phase regulator include six rectifier tubes D1-D6 constitute three-phase rectifier bridge and with insulated gate bipolar transistor T1, three AC input of three-phase rectifier bridge is connected with the tie point A3 of stator secondary winding respectively, B3, C3, the positive output of direct current and the negative output of direct current of three-phase rectifier bridge are connected with the C utmost point and the E utmost point of insulated gate bipolar transistor T1 respectively, three-phase rectifier bridge direct current positive output and direct current negative output are connected with the negative pole and the positive pole of rectifier tube D7 respectively simultaneously, at the regulator full conducting state, constitute looks triangle combined circuit.

4. The automatic internal compensation control device for the asynchronous motor capacitor as recited in claim 1, further comprising a rotor winding, AC switches K2 and K3,

the stator main winding connection points A2, B2 and C2 are respectively connected with main capacitors C01, C02 and C03, the main capacitors C01, C02 and C03 are connected end to form triangular connection,

the regulator is a three-phase regulator, the three-phase regulator comprises a three-phase rectifier bridge consisting of six rectifier tubes D1-D6 and an insulated gate bipolar transistor T1, three alternating current input ends of the three-phase rectifier bridge are respectively connected with connection points A3, B3 and C3 of a stator secondary winding, a direct current positive output end and a direct current negative output end of the three-phase rectifier bridge are respectively connected with a C pole and an E pole of the insulated gate bipolar transistor T1, and a direct current positive output end and a direct current negative output end of the three-phase rectifier bridge are respectively connected with a cathode and an anode of the rectifier tube D7,

the rotor winding comprises three-phase windings Wa3, Wb3 and Wc3, one ends of the three-phase windings Wa3, Wb3 and Wc3 are connected together, and the other ends of the three-phase windings Wa3, Wb3 and Wc3 are respectively connected with stator main winding connection points A3, B3 and C3 through an alternating current switch K2 and are short-circuited through an alternating current switch K3.

5. The automatic internal compensation control device for asynchronous motor capacitance according to any of claims 1-4 is characterized in that the capacity ratio of the main capacitor and the auxiliary capacitor is 5:1-5, and the ratio of the sum KVA of the capacities of the main capacitor and the auxiliary capacitor to the input power KW of the asynchronous motor is 2-4: 5.

6. A method for controlling a regulator of an automatic internal capacitance compensation control device for an asynchronous motor according to claim 1, comprising the steps of:

firstly, respectively sampling phase voltage and current of an asynchronous motor by using a one-way transformer and a current transformer,

secondly, signal conversion is carried out to convert the voltage quantity and the current quantity into voltage phasor of 5-10V respectively,

thirdly, phase comparison is performed, a phase difference value between the voltage amount and the current amount is converted into a signal, in the latter phase transition delayed from the former by 90 degrees to 0 degrees, the comparison signal is gradually decreased,

fourthly, performing logic operation, performing operation according to the initial setting signal to give a signal of a direct current value,

and fifthly, pulse width modulation adopts a triangular carrier comparison method with the carrier frequency of 5-15KHZ, when the phase difference between the two is larger, the conduction width of an insulated gate bipolar transistor in the regulator is larger, otherwise, the conduction width is smaller, so that the voltage value of the secondary winding and the capacitance of the secondary capacitor are dynamically adjusted, and the automatic internal compensation effect is achieved.

Technical Field

The invention belongs to the technical field of asynchronous motors and electric transmission, and particularly relates to an automatic internal compensation control device for an asynchronous motor capacitor.

Background

When the asynchronous motor is started, the rotor starts to rotate from a static state, the rotating speed is very low, the relative cutting speed of a rotating magnetic field and the rotor is very high, the induced electromotive force of a rotor winding is very large, the induced current is also very large, and meanwhile, the current of a stator winding is also very large, so that the starting current is very large. The starting current of the asynchronous motor is large, the voltage of a power grid fluctuates, normal operation of other equipment connected to the power grid is influenced, heating of a motor winding is easily caused, insulation aging is easily caused, and the service life of the motor is shortened. For heavy load starting of a ball mill and the like, in order to reduce starting current, the prior art adopts a frequency sensitive rheostat or other current limiting equipment, and has the problem of larger starting current. The double-winding capacitor internal compensation motor of the chinese patent 012286052 is designed such that the main and auxiliary stator windings are respectively designed as delta or star connections, and the capacitor is also connected to the compensation end of the auxiliary winding with a certain fixed capacity, and there still exists a problem of large current when the direct start mode is adopted for the motor, especially the compensation current of the motor cannot be dynamically adjusted, so that the problem of insufficient compensation current or over compensation current is often generated in the practical application. The zigzag connection internal compensation asynchronous motor of the Chinese patent 201203179480 adopts inequilateral hexagon zigzag connection to equivalently connect in parallel the principle of exciting inductive reactance two ends of the motor, has certain energy-saving effect on reducing leakage reactance voltage drop, hysteresis loss and reactive loss of the stator, but can generate non-sinusoidal compensation current, and the starting current is still large.

Disclosure of Invention

The invention aims to provide an automatic internal compensation control device for asynchronous motor capacitors, which carries out internal compensation on current through three V-shaped winding wiring and two groups of capacitors, and simultaneously utilizes a regulator to carry out reactive dynamic regulation, thereby reducing the starting current of an asynchronous motor.

The invention provides an asynchronous motor capacitance automatic internal compensation control device, which comprises a stator winding, an alternating current power supply, main capacitors C01-C03, auxiliary capacitors C04-C06, a regulator and an alternating current switch K1, wherein the stator winding comprises three-phase main windings Wa1, Wb1, Wc1, three-phase auxiliary windings Wa1, Wb1 and Wc1, the head end of the Wa1 is connected with the tail end of the Wc1, the connection point is A1, the head end of the Wb1 is connected with the tail end of the Wa1, the connection point is C1, three connecting wires with V-shaped potential phasor are formed, the tail ends of the main windings Wa1, Wb1 and Wc1 are respectively connected with the A1, B1 and C1, the head ends of the auxiliary windings Wa1, Wb1 and Wc1 are respectively connected with the head ends of the connection points 1, B1 and C1, the connection points are respectively connected with the AC switches 1A 1, B1 and C1, B1 and C1, a1 and a1 are respectively connected with a nine basic circuits 1, 1 and a1, a1 and a1, a1 and C1 are respectively, a1 and a1 are respectively connected with a1, a circuit, a1, a circuit is led out, B0 and C0, sub capacitors C04, C05 and C06 are respectively connected between a connection point A2 and C3, between B2 and A3 and between B3 and C2, the main capacitors C01-C03 are connected with the tail ends of main windings Wa1, Wb1 and Wc1, the regulators are connected with the head ends of the sub windings Wa2, Wb2 and Wc2, and voltage and current regulation is carried out on the connection points A3, B3 and C3 by PWM control.

Further, main capacitors C01, C02 and C03 are respectively connected between the stator main winding connection point A2 and C1, between B2 and A1 and between C2 and B1, the regulators comprise three single-phase regulators, a single-phase rectifier bridge consisting of four rectifier tubes D1-D4/D5-D8/D9-D12 and an insulated gate bipolar transistor T1/T2/T3 are respectively connected between the main winding connection point A1 and A3, between B1 and B3 and between C1 and C3, a direct current positive output end and a direct current negative output end of the single-phase rectifier bridge are respectively connected with a C pole and an E pole of the insulated gate bipolar transistor T1/T2/T3, and a direct current positive output end and a direct current negative output end of the single-phase rectifier bridge are respectively connected with a cathode and an anode of the insulated gate bipolar transistor D13/D14/D15.

Further, main capacitors C01, C02 and C03 are respectively connected between the stator main winding connection points A2 and C1, B2 and A1, and between C2 and B1, and the turn ratio of the main winding to the auxiliary winding is V3: 1, the voltage phasor of secondary winding is than 30 degrees electrical angle settings in advance of homophase main winding, the regulator is three-phase regulator, three-phase regulator include six rectifier tubes D1-D6 constitute three-phase rectifier bridge and with insulated gate bipolar transistor T1, three AC input of three-phase rectifier bridge is connected with the tie point A3 of stator secondary winding respectively, B3, C3, the positive output of direct current and the negative output of direct current of three-phase rectifier bridge are connected with the C utmost point and the E utmost point of insulated gate bipolar transistor T1 respectively, three-phase rectifier bridge direct current positive output and direct current negative output are connected with the negative pole and the positive pole of rectifier tube D7 respectively simultaneously, at the regulator full conducting state, constitute looks triangle combined circuit.

The three-phase rectifier comprises a stator main winding connection point A2, a stator main winding connection point B2 and a stator main winding connection point C2 which are respectively connected with a main capacitor C01, a main capacitor C02 and a main capacitor C03, wherein the main capacitor C01, a stator main winding connection point C02 and the stator main winding connection point C03 are connected end to form triangular connection, the three-phase regulator is a three-phase regulator and comprises six rectifier tubes D1-D6, a three-phase rectifier bridge and an insulated gate bipolar transistor T1, three alternating current input ends of the three-phase rectifier bridge are respectively connected with a connection point A3, a connection point B3 and a connection point C3 of a stator secondary winding, direct current positive output ends and direct current negative output ends of the three-phase rectifier bridge are respectively connected with a C pole and an E pole of the insulated gate bipolar transistor T1, direct current positive output ends and direct current negative output ends of the three-phase rectifier bridge are respectively connected with a cathode and an anode of the rectifier tube D7, and the rotor winding connection point A639, the three-phase winding connection point Wb 6862, the three-phase winding Wc winding connection point Wb 8269556, the stator winding connection point Wa 53, the three-phase winding connection point Wb 84 3 and the three-phase winding connection point Wb 848653, the three-phase winding connection point Wb 84 3, the three-phase rectifier bridge are respectively, One ends of Wc3 are connected together, and the other ends of three-phase windings Wa3, Wb3 and Wc3 are respectively connected with stator main winding connection points A3, B3 and C3 through an alternating current switch K2 and are short-circuited through the alternating current switch K3.

Furthermore, the capacity ratio of the main capacitor to the auxiliary capacitor is 5:1-5, and the ratio of the sum KVA of the capacities of the main capacitor and the auxiliary capacitor to the input power KW of the asynchronous motor is 2-4: 5.

The invention provides a regulator control method of an asynchronous motor capacitor automatic internal compensation control device, which comprises the following steps:

firstly, respectively sampling phase voltage and current of an asynchronous motor by using a one-way transformer and a current transformer,

secondly, signal conversion is carried out to convert the voltage quantity and the current quantity into voltage phasor of 5-10V respectively,

thirdly, phase comparison is performed, a phase difference value between the voltage amount and the current amount is converted into a signal, in the latter phase transition delayed from the former by 90 degrees to 0 degrees, the comparison signal is gradually decreased,

fourthly, performing logic operation, performing operation according to the initial setting signal to give a signal of a direct current value,

and fifthly, pulse width modulation adopts a triangular carrier comparison method with the carrier frequency of 5-15KHZ, when the phase difference between the two is larger, the conduction width of an insulated gate bipolar transistor in the regulator is larger, otherwise, the conduction width is smaller, so that the voltage value of the secondary winding and the capacitance of the secondary capacitor are dynamically adjusted, and the automatic internal compensation effect is achieved.

The invention has the following beneficial effects: the invention uses the main capacitor to carry out capacitance internal compensation on the main winding in advance and provides more than 50% of initial current, so that the rotating speed of the common asynchronous motor is close to more than 50%, then the regulator is used for carrying out dynamic adjustment, the starting of various equipment including heavy-load equipment is completed by using smaller starting current, and meanwhile, the output voltage is changed through the regulator to carry out dynamic adjustment on the fan and pump motors within the range of 50% -100% of rated rotating speed, and the effect that the power factor is 1.0 is achieved.

Drawings

Fig. 1 is a wiring diagram of an automatic internal compensation control device of an asynchronous motor capacitor according to embodiment 1 of the invention.

Fig. 2 is a wiring diagram of an automatic internal compensation control device of the asynchronous motor capacitor in embodiment 2 of the invention.

Fig. 3 is a wiring diagram of an automatic internal compensation control device of the asynchronous motor capacitor in embodiment 3 of the invention.

FIG. 4 is a flow chart of a method for modulating the pulse width of the regulator according to the present invention.

Detailed Description

In order to clearly illustrate the technical features of the present solution, the following explains the present solution by way of specific embodiments and with reference to the accompanying drawings.

Example 1

As shown in figure 1, the automatic internal compensation control device for the capacitance of the asynchronous motor comprises a stator winding, an alternating current power supply, main capacitors C01-C03, auxiliary capacitors C04-C06, a regulator and an alternating current switch K1.

The stator windings comprise three-phase main windings Wa1, Wb1, Wc1 and three-phase auxiliary windings Wa2, Wb2, Wc 2. The ratio of the induced voltage values of the main winding and the auxiliary winding is 1: 1. The head end of Wa1 is connected with the tail end of Wc2, the connection point is A1, the head end of Wb1 is connected with the tail end of Wa2, the connection point is B1, the head end of Wc1 is connected with the tail end of Wb2, the connection point is C1, and three connections with V-shaped potential vectors are formed. The connection points a1, B1, and C1 are connected to ac power supply terminals a0, B0, and C0, respectively, via an ac switch K1.

Designing a winding: considering that the compensation in the capacitor has the function of eliminating leakage reactance, the winding design can be carried out according to 380-400V for a low-voltage motor. Taking a stator wire casing with 36 slots, a pitch y =8 and a pole number of 4 as an example, the connection mode is described as follows: each coil group takes the slot number of the coil positioned at the upper layer as a mark, one end of the winding plus "·" is used as the head end, the other end is used as the tail end, two coil groups numbered 1, 2, 3, 19, 20 and 21 are connected in parallel to form a main winding Wa1, two coil groups numbered 10, 11, 12, 28, 29 and 30 are connected in parallel to form a secondary winding Wa2, Wb1 and Wc1 are sequentially pushed back to 6 wire slots to be discharged, and two secondary windings Wb2 and Wc2 are also sequentially pushed back to 6 wire slots to be discharged.

The tail ends of the main windings Wa1, Wb1 and Wc1 are respectively connecting points A2, B2 and C2, the head ends of the auxiliary windings Wa2, Wb2 and Wc2 are respectively connecting points A3, B3 and C3, auxiliary capacitors C04, C05 and C06 are respectively connected between the connecting points A2 and C3, B2 and A3 and between C2 and B3, and main capacitors C01, C02 and C03 are respectively connected between the connecting points A2 and C1, B2 and A1 and between C2 and B1.

The main capacitors C01, C02 and C03 respectively perform the previous internal capacitance compensation on the main windings Wa1, Wb1 and Wc1, and the connection of the main windings and the auxiliary windings is utilized to ensure that the auxiliary windings cannot generate excessive current due to sudden change of current when the regulator is switched on and off rapidly. For example, the C5 secondary capacitor connected in series with the Wa2 secondary winding maintains the voltage value at the A3 terminal constant instantaneously. Because the three secondary windings have winding leakage inductance, the three secondary capacitors generate follow current action on the three regulators; for example, when the terminal B3 is cut off instantaneously, the current flowing through Wb2 will be provided with an auxiliary path by the auxiliary capacitor C06, and finally the single-phase regulator connected with the terminal B1 and the terminal B3 is cut off and then voltage flicker is avoided by the freewheeling action of the auxiliary capacitor C06. The three secondary windings and the three secondary capacitors are connected in a 120 electrical degree lagging manner, so that the current phase in the secondary windings is advanced by 30 electrical degrees, the current phase of the main windings is lagged by 30 electrical degrees, for example, the wc2 winding current phase is advanced by 30 degrees, and the wa1 winding current is lagged by 30 degrees, and the voltage phasor and the current phasor of the motor are close to and in the same phase by adding the three secondary windings and the three secondary capacitors. If the two groups of capacitors are selected according to half of the rated current value of the motor, the current values and current phases of the main winding and the secondary winding are the same when the rated current value is close, so that the power factor of the motor is close to 1.0, and the three-phase load current value is reduced by 15%. The main and auxiliary two winding end points with an included angle of 60 degrees are connected with a capacitor, which is the technical point of internal compensation.

The regulator comprises three unidirectional regulators, a unidirectional regulator is respectively connected between a main winding connection point A1 and A3, between B1 and B3, between C1 and C3, the single-phase regulator comprises a single-phase rectifier bridge consisting of four rectifier tubes D1-D4/D5-D8/D9-D12 and an insulated gate bipolar transistor T1/T2/T3, a direct current positive output end and a direct current negative output end of the single-phase rectifier bridge are respectively connected with a C pole and an E pole of the insulated gate bipolar transistor T1/T2/T3, and a direct current positive output end and a direct current negative output end of the single-phase rectifier bridge are respectively connected with a cathode and an anode of the rectifier tube D13/D14/D15 to ensure the reliable disconnection of the unidirectional rectifier bridge. When the three regulators are close to full conduction, voltages of three ends A3, B3 and C3 are close to voltages of three ends A1, B1 and C1.

The control method of the regulator is shown in fig. 4 and comprises the following steps:

firstly, sampling phase voltage and current of an asynchronous motor by using a one-way transformer and a current transformer respectively,

secondly, signal conversion is carried out to convert the voltage quantity and the current quantity into voltage phasor of 5-10V respectively,

thirdly, phase comparison is performed, a phase difference value between the voltage amount and the current amount is converted into a signal, in the latter phase transition delayed from the former by 90 degrees to 0 degrees, the comparison signal is gradually decreased,

fourthly, performing logic operation, performing operation according to the initial setting signal to give a signal of a direct current value,

and fifthly, pulse width modulation adopts a triangular carrier comparison method with the carrier frequency of 5-15KHZ, when the phase difference between the two is larger, the conduction width of an insulated gate bipolar transistor in the regulator is larger, otherwise, the conduction width is smaller, so that the voltage value of the secondary winding and the capacitance of the secondary capacitor are dynamically adjusted, and the automatic internal compensation effect is achieved.

Example 2

As shown in figure 2, the automatic internal compensation control device for the asynchronous motor capacitor comprises a stator winding, an alternating current power supply, main capacitors C01-C03, auxiliary capacitors C04-C06, a regulator and an alternating current switch K1. The stator winding comprises three-phase main windings Wa1, Wb1 and Wc1 and three-phase auxiliary windings Wa2, Wb2 and Wc2, the ratio of the induced voltage values of the main windings to the induced voltage values of the auxiliary windings is √ 3:1, and the voltage phasor of the auxiliary windings is set 30 electrical degrees ahead of that of the main windings. The head end of Wa1 is connected with the tail end of Wc2, the connection point is A1, the head end of Wb1 is connected with the tail end of Wa2, the connection point is B1, the head end of Wc1 is connected with the tail end of Wb2, the connection point is C1, and three connections with potential phasors in a V shape are formed. The connection points a1, B1, and C1 are connected to ac power supply terminals a0, B0, and C0, respectively, via an ac switch K1.

The three auxiliary windings Wa2, Wb2 and Wc2 are respectively advanced by 30 degrees in electrical angle and designed into a phase voltage value of 220V, the three main windings Wa1, Wb1 and Wc1 are designed into a line voltage value of 380V, and the sections of the wires of the three main windings Wa1, Wb1 and Wc1 are correspondingly enlarged. The winding design adopts a phase belt combination mode or a double-layer arrangement mode with a polar phase group of 30, wherein the double-layer arrangement mode refers to a connection mode that a main winding and an auxiliary winding are arranged in two layers and form an included angle of 30 degrees with the main winding. For example, the angle between the windings Wa1 and Wc2 is 30 electrical degrees.

The tail ends of the main windings Wa1, Wb1 and Wc1 are respectively connecting points A2, B2 and C2, the head ends of the auxiliary windings Wa2, Wb2 and Wc2 are respectively connecting points A3, B3 and C3, auxiliary capacitors C04, C05 and C06 are respectively connected between the connecting points A2 and C3, B2 and A3 and between C2 and B3, and main capacitors C01, C02 and C03 are respectively connected between the connecting points A2 and C1, B2 and A1 and between C2 and B1.

The three-phase regulator comprises a three-phase rectifier bridge consisting of six rectifier tubes D1-D6 and an insulated gate bipolar transistor T1, three alternating current input ends of the three-phase rectifier bridge are respectively connected with connection points A3, B3 and C3 of a stator secondary winding, a direct current positive output end and a direct current auxiliary output end of the three-phase rectifier bridge are respectively connected with a C pole and an E pole of the insulated gate bipolar transistor T1, and a direct current positive output end and a direct current auxiliary output end of the three-phase rectifier bridge are respectively connected with a cathode and an anode of the rectifier tube D7. When the regulator is fully conducted, a combined circuit with potential phasor of star-triangle is formed. The three ends A3, B3 and C3 of the secondary winding can be connected with a rotor circuit for heavy load starting.

The control method of the regulator is the same as in embodiment 1.

Example 3

As shown in figure 3, the automatic internal compensation control device for the asynchronous motor capacitor comprises a stator winding, a rotor winding, an alternating current power supply, main capacitors C01-C03, auxiliary capacitors C04-C06, a regulator, and alternating current switches K1, K2 and K3. The stator winding comprises three-phase main windings Wa1, Wb1 and Wc1 and three-phase auxiliary windings Wa2, Wb2 and Wc2, and the ratio of the induced voltage values of the main windings to the auxiliary windings is 1: 1. The head end of Wa1 is connected with the tail end of Wc2, the connection point is A1, the head end of Wb1 is connected with the tail end of Wa2, the connection point is B1, the head end of Wc1 is connected with the tail end of Wb2, the connection point is C1, and three connections with V-shaped potential vectors are formed. The connection points a1, B1, and C1 are connected to ac power supply terminals a0, B0, and C0, respectively, via an ac switch K1.

The tail ends of the main windings Wa1, Wb1 and Wc1 are respectively connecting points A2, B2 and C2, the head ends of the auxiliary windings Wa2, Wb2 and Wc2 are respectively connecting points A3, B3 and C3, auxiliary capacitors C04, C05 and C06 are respectively connected between the connecting points A2 and C3 and between B2 and A3 and between C2 and B3, the connecting points A2, B2 and C2 are respectively connected with the main capacitors C01, C02 and C03, and the main capacitors C01, C02 and C03 are connected end to form triangular connection. The main capacitors C01, C02 and C03 and the main windings Wa1, Wb1 and Wc1 are in a zigzag series connection relationship with the angle of lagging by 120 degrees, the auxiliary capacitors C04, C05 and C06 and the auxiliary windings Wa2, Wb2 and Wc2 are also in a zigzag series connection relationship, and the two groups of capacitors can generate the effect of being connected in parallel with two ends of a motor excitation inductive reactance, so that the number of turns of the main winding and the auxiliary winding can be increased by 5 percent and 10 percent compared with the conventional design, and the gap magnetic density of the motor is ensured to be between 0.65T and 0.7T.

When the regulator is fully conducted, the voltages of the main winding and the auxiliary winding are respectively 220V phase voltages, and the potential phasors are three V-shaped; the main capacitor is used for carrying out capacitance internal compensation on the three-phase main winding, and the connection relation between the main capacitor and the auxiliary winding is utilized, so that the auxiliary winding cannot generate overlarge current due to sudden change of current when the regulator is quickly switched on and switched off. For example, the auxiliary capacitor C06 connected in series with the auxiliary winding Wb2 maintains the voltage value at the B3 terminal constant instantaneously, and similarly, the voltages at the A3 and C3 terminals constant instantaneously; three main windings can use three auxiliary capacitors to generate instantaneous follow current action on three regulators due to winding leakage inductance; for example, when the regulator is switched off rapidly, the end A3 is cut off instantaneously, the current flowing through Wa2 is provided with an auxiliary path by the auxiliary capacitor C05, and the winding Wb1 is correspondingly changed, so that voltage flicker is avoided after the regulator is cut off by the follow current action of the auxiliary capacitor C05.

The regulator is a three-phase regulator, the three-phase regulator comprises a three-phase rectifier bridge consisting of six rectifier tubes D1-D6 and an insulated gate bipolar transistor T1, three alternating current input ends of the three-phase rectifier bridge are respectively connected with connection points A3, B3 and C3 of a stator secondary winding, a direct current positive output end and a direct current auxiliary output end of the three-phase rectifier bridge are respectively connected with a C pole and an E pole of an insulated gate bipolar transistor T1, a G pole is connected with a PWM control link, and meanwhile, a direct current positive output end and a direct current auxiliary output end of the three-phase rectifier bridge are respectively connected with a cathode and an anode of a rectifier tube D7.

The rotor winding comprises three-phase windings Wa3, Wb3 and Wc3, one ends of the three-phase windings Wa3, Wb3 and Wc3 are connected together, and the other ends of the three-phase windings Wa3, Wb3 and Wc3 are respectively connected with main winding connection points A3, B3 and C3 of the stator through an alternating current switch K2 and are short-circuited through an alternating current switch K3.

When three terminals of the wound rotor are connected with three adjusting ends A3, B3 and C3 of a stator winding to form a combined loop through an alternating current switch K2, the rotor winding is induced with voltage close to the power frequency by a large difference rate at the initial starting stage of the motor, the self impedance forms a loop with the power through three-phase auxiliary windings wa2, wb2 and wc2, and a part of the motor forms a loop with the three auxiliary windings through three auxiliary capacitors, but the motor plays a leading role or forms an adjusting loop through an adjuster.

When the motor is started, the regulator is preset between half conduction and full conduction, and is transited to full conduction in the starting process, in the gradual conduction process of the regulator, the stator winding becomes the impedance of the rotor winding, the open-circuit rotor winding voltage is transited to zero value gradually through the PWM regulation mode that the three-phase input voltage is transited from 220V to zero value gradually, when the starting is nearly completed, the voltage value among the connection points A3, B3 and C3 is gradually approached to zero, finally, the AC switch K3 is closed, and the AC switch K2 connected with the stator winding is simultaneously disconnected, so that the low-current starting process is completed, and the motor runs at the rated rotating speed. The control method of the regulator is the same as in examples 1 and 2 except that an initial setting is added when the logical operation is performed.

In the three embodiments, the rated voltage of the main capacitor and the auxiliary capacitor is 230V-450V, the capacity ratio of the main capacitor to the auxiliary capacitor is 5:1-5, the sum KVA of the capacities of the main capacitor and the auxiliary capacitor and the input power KW of the motor are 2-4: 5.

the above-mentioned embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and alterations made to the technical solution of the present invention by those skilled in the art without departing from the spirit of the present invention shall fall within the protective scope defined by the claims of the present invention.