CN202550961U

CN202550961U - Frequency conversion energy-saving device of low-voltage three-phase asynchronous motor control system

Info

Publication number: CN202550961U
Application number: CN201120445183XU
Authority: CN
Inventors: 裴古炎; 潘书祥; 柯有玺; 刘彩
Original assignee: ANHUI HETIAN ELECTRIC Co Ltd
Current assignee: ANHUI HETIAN ELECTRIC Co Ltd
Priority date: 2011-11-11
Filing date: 2011-11-11
Publication date: 2012-11-21
Anticipated expiration: 2021-11-11

Abstract

The utility model discloses a frequency conversion energy-saving device of a low-voltage three-phase asynchronous motor control system. The frequency conversion energy-saving device comprises an asynchronous motor, an AC contactor, a breaker and a frequency converter. The asynchronous motor, the frequency converter, the AC contactor and the breaker are in series connection successively in a flexible manner. According to the device of the utility model, the original frequency converter is accessed into a low-voltage three-phase asynchronous motor control system, thereby adjusting and controlling power factors and load power of a load. Therefore, the low-voltage three-phase asynchronous motor control system exhibits a better energy-saving effect compared with a conventional control system.

Description

Low-voltage three phase asynchronous motor control system frequency converting and energy saving device

Technical field

The utility model relates to the AC low-tension threephase asynchronous, relates in particular to the frequency converting and energy saving device of low-voltage three phase asynchronous motor control system.

Background technology

Control mode and working method that present threephase asynchronous adopts can be divided into following several kinds:

A, direct start-up control mode, power frequency operation;

B, star triangle start control mode, power frequency operation;

C, compensator starting control mode, power frequency operation;

D, frequency sensitive trheostat start-up control mode (rotor wire wound type asynchronous motor), rotor-side variable frequency starts (difference on the frequency is bigger), power frequency operation;

E, soft start control mode, power frequency operation.

In the above-mentioned several kinds of control modes, a, b class Starting mode are applicable to small power motor or the lighter application places of load, and c, d, e class Starting mode are applicable to the big or heavier application places of load of power of motor.

More than five kinds of control modes all have certain shortcoming:

Inevitably there are very big mechanical shock in a, b, c class start-up control mode on the control load mechanical property, for the machining class, cause impact damage or damage, the belt creep wearing and tearing of gear easily; For the blower fan load of the pumps, cause impeller of blower moment to quicken and be out of shape easily, and water pump moment draw water pipeline is produced water hammer effect and causes pipeline breaking or the damage of accumulative total property.And the power factor of load and bearing power can't regulate, and do not possess energy-efficient performance;

D, e class control mode are relatively milder on the load machinery characteristic, and the electric current of control motor also is controlled in the scope of design, but the power factor of load and bearing power can't regulate, and do not possess energy-efficient performance.

In sum, the control mode that existing threephase asynchronous adopts all can't be regulated the power factor and the bearing power of load, and energy-efficient performance is not good.

The utility model content

To above defective, the utility model provides a kind of frequency converting and energy saving device of low-voltage three phase asynchronous motor control system, solves the problem that existing threephase asynchronous control mode can't be regulated the power factor and the bearing power of load.

For realizing above-mentioned purpose, the utility model is realized through following technical scheme:

Low-voltage three phase asynchronous motor control system frequency converting and energy saving device comprises asynchronous motor, A.C. contactor and circuit breaker, also comprises frequency converter, and asynchronous motor, frequency converter, A.C. contactor and circuit breaker elasticity are connected in series successively.

The utility model is through Inverter Application, can produce energy-saving effect aspect following three:

1, energy-saving and frequency-variable

Can know by fluid mechanics, P (power)=Q (flow) * H (pressure), flow Q is directly proportional with the first power of rotational speed N, square being directly proportional of pressure H and rotational speed N, cube being directly proportional of power P and rotational speed N.If the efficient of water pump is certain, when requiring to regulate flow decline, rotational speed N can proportionally descend, and this moment, shaft power P became cubic relationship to descend, and promptly the power consumption of pump motor is approximated to cube relation of ratio with rotating speed.For example: a pump motor power is 55KW, when rotating speed drop to former rotating speed 4/5 the time, its power consumption is 28.16KW, power saving 48.8%, when rotating speed drop to former rotating speed 1/2 the time, its power consumption is 6.875KW, power saving 87.5%.Therefore, in the utility model, can realize adjusting, thereby reach the purpose of quick reduction power consumption rotating speed.

2, power factor compensation is energy-conservation

Reactive power not only increases the heating of line loss and equipment, and the reduction of power factor that main is causes the reduction of electric network active power, and a large amount of reactive energy consumption are in the middle of circuit, and the equipment service efficiency is low; Waste is serious, by formula P=S * COS Ф, and Q=S * SIN Ф, wherein S-apparent power; P-active power, Q-reactive power, COS Ф-power factor can know that COS Ф is big more; Active power P is big more, and the power factor of light water pump motor is between 0.6-0.7, behind the use RHVC, because the effect of the inner filter capacitor of frequency converter; COS Ф ≈ 1, thus reactive loss reduced, increased the active power of electrical network.

3, frequency conversion soft start is energy-conservation

Directly start or during the star triangle start, starting current approximates 4-7 times of rated current, can cause serious impact to electromechanical equipment and power supply grid like this, but also can require too high to net capacity at motor.The vibrations that the big electric current that produces during startup causes are very big to the infringement of baffle plate and valve, and are totally unfavorable to the useful life of equipment, pipeline.And behind the use frequency converting and energy saving device; Utilize the soft start function of frequency converter that starting current will be started from scratch, maximum also is no more than rated current, has alleviated to the impact of electrical network with to the requirement of power supply capacity; Prolong the useful life of equipment and valve, saved the maintenance cost of equipment.

Description of drawings

According to embodiment and accompanying drawing the utility model is done further explain below.

Figure 1A and Figure 1B are the control and the operation electric diagram of directly startup and star triangle start;

Fig. 2 A and Fig. 2 B are control and the operation electric diagram that auto coupling decompression start and frequency sensitive trheostat start;

Fig. 3 is the control and the operation electric diagram of the said frequency converting and energy saving device of the utility model.

Among the figure:

1, asynchronous motor; 2, thermal relay; 3, A.C. contactor; 4, circuit breaker; 5, autotransformer; 6, frequency sensitive trheostat; 7, frequency converter.

Embodiment

Shown in Fig. 1-3; Provided the structural representation of a specific embodiment of the said low-voltage three phase asynchronous motor control system of the utility model frequency converting and energy saving device; Low-voltage three phase asynchronous motor control system frequency converting and energy saving device; Comprise asynchronous motor 1, A.C. contactor 3, circuit breaker 4 and frequency converter 7, asynchronous motor 1, frequency converter 7, A.C. contactor 3 and circuit breaker 4 elasticity are connected in series successively.

Shown in Figure 1A, when directly starting, directly start asynchronous motor 1 operation through A.C. contactor 3, thermal relay 2 is as asynchronous motor 1 thermal overload protection.Shown in Figure 1B, during the star triangle start, asynchronous motor 1 is in star decompression starting mode, and asynchronous motor 1 was in the triangle operational mode after delayed startup finished.

Shown in Fig. 2 A, during auto coupling decompression start, asynchronous motor 1 is in the reduced-voltage starting mode of 65% tap of self coupling transformation, asynchronous motor 1 total head operation after delayed startup or electric current drop to set point, and this moment, autotransformer 5 was out of service.Shown in Fig. 2 B, when frequency sensitive trheostat 6 started, the winding of asynchronous motor 1 coil wound rotor was connected in series in the winding of frequency sensitive trheostat 6 through the collector ring of asynchronous motor 1; This moment, the rotor speed difference was big, and power frequency is bigger, and asynchronous motor 1 startup presents hardware features; Detent torque is bigger; After startup finished, frequency sensitive trheostat 6 was out of service, and the winding of the coil wound rotor of asynchronous motor 1 is through the collector ring of asynchronous motor 1; By A.C. contactor 3 short circuits, this moment, asynchronous motor 1 was in the total head running status.

As shown in Figure 3, be an embodiment of the utility model, the startup of asynchronous motor 1 and operation all are in the VFC state, and operating frequency is determined by the setup parameter of frequency converter 7.

The utility model has realized that through former frequency converter is inserted the low-voltage three phase asynchronous motor control system original relatively control system has better energy-saving effect to the adjusting control of the power factor and the bearing power of load.

Claims

1. low-voltage three phase asynchronous motor control system frequency converting and energy saving device comprises asynchronous motor, A.C. contactor and circuit breaker, it is characterized in that: also comprise frequency converter, asynchronous motor, frequency converter, A.C. contactor and circuit breaker elasticity are connected in series successively.