CN85100389B - Dynamic testing method and its app. for the torque-speed characteristics of asynchronous motor - Google Patents

Abstract

A dynamic test method and device for torque-speed characteristic of an asynchronous motor. The test method is: adding a flywheel with flywheel torques of GD12, GD22... respectively on the motor shaft of the test, and establishing a speed n with time during start and stop The moving equations of t change law, select the microcomputer system, use the incremental pulse timing method to sample, process and draw the curve. The device for realizing the test method is composed of a plurality of flywheels, a flywheel adapter sleeve, a speed sensor, a voltage and current transmitter, and a microcomputer system. The invention has the advantages of low investment, high precision, convenient operation and adaptability to testing of different power asynchronous motors.

Description

Dynamic testing method and its app. for the torque-speed characteristics of asynchronous motor

The present invention relates to method of testing and the device of motor torque, rotating speed.

At present for induction motors torque---the method for testing of rotation speed characteristic has multiple.

In American National Standard ANSI/IEEE std 112-1978, there are actual measurement input method, actual measurement output method, the direct method of measurement; Actual measurement input method is the every loss that deducts tested motor the power input from recording, thereby determines torque; Actual measurement output method is to do load with corrected Dyn., is obtained the torque of tested motor by this Dyn. output power and every loss sum; The direct method of measurement is done load mainly with dynamometer machine, directly measures the torque under different rotating speeds.Actual measurement input method precision is lower, and actual measurement output method and dynamometer machine method are comparatively accurate, but can only record the output power on tested motor reel, and can not record electromagnetic power; Adopt above-mentioned method of testing, and all need on tested motor reel, apply and its torque, the corresponding adjustable load of rotation speed change scope, so expensive, take up an area greatly big energy-consuming.

The dynamic testing method of introducing in GB1032-68 appendix four (the 249th page, medium and small motor standard compilation) is: in general motor

be a constant, the torque producing when motor no-load starting can be used

represent, when the torque M for overcoming friction ₀than omitting in the quite little situation of whole torque M of motor generation itself, be

be the torque that the acceleration of motor is proportional to motor, if by the rotating speed of motor to time diffusion, just can be proportional to the numerical value of torque.According to this principle, adopt detecting element (tech-generator) to record every flashy rotating speed in tested motor starting procedure, the voltage signal of the speed that is proportional to of then detecting element being sent and the signal after differential element (capacitance network) differential thereof are sent into respectively the oscillographic X of scanning, Y-axis, and show, can survey M-n curve.Formed by tech-generator, capacitance network, scanning oscillograph or X-y registering instrument for the existing device of realizing described method.Use described method of testing and device first to measure motor rotor by other approach when not ignoring M ₀time, must first measure M ₀, can calculate M, process trouble, complicated operation, and precision is low.

The object of this invention is to provide a kind of measuring accuracy high, easy and simple to handle, and obtain in measuring M

and M ₀, be suitable for the test characteristic dynamic testing method of different capacity asynchronous motor and device.

The method of solution task is: the flywheel that adds respectively different known its flywheel moment numerical value on tested motor reel, make electric motor starting and stop, set up the mobile equation group in starting and stopped process, adopt increasing pulse timing, processed by microsystem, show that family curve and design complete the device of above-mentioned test process.

When direct motor drive torque is M, unloaded resistive torque is M ₀, rotor flywheel moment is

time, according to spin dynamics formula $M-M_0=\frac{{\mathrm{GD}}_0^2}{375}\·\frac{d_n}{d_t}$ Can obtain torque equation group:

$\left\{\begin{array}{c}M-M_0=\frac{{\mathrm{GD}}_0^2}{375}\left(\frac{d_n}{d_t}\right)I\\ -M_0=\frac{{\mathrm{GD}}_0^2}{375}\left(\frac{d_n}{d_t}\right)\mathrm{II}\end{array}\right.$

On this basis, on tested motor reel, additional known flywheel moment is the inventive method respectively

flywheel, in the time of an every additional flywheel, make motor starting and stop once, obtain two corresponding differential equations, these two differential equations have been described respectively starting and the stopped process medium speed n Changing Pattern of t in time, when additional flywheel moment is respectively

flywheel time, can obtain following four equations:

$M-{\mathrm{aM}}_0=\frac{{\mathrm{GD}}_0^2+{\mathrm{<figure-callout\; id="1"\; label="GD"\; filenames="H85100389E0000051.png"\; state="\{\{state\}\}">GD</figure-callout>}}_1^2}{375}{\left(\frac{d_n}{d_t}\right)}_1---\left(1\right)$

$-{\mathrm{aM}}_0=\frac{{\mathrm{GD}}_0^2+{\mathrm{<figure-callout\; id="1"\; label="GD"\; filenames="H85100389E0000051.png"\; state="\{\{state\}\}">GD</figure-callout>}}_1^2}{375}{\left(\frac{d_n}{d_t}\right)}_2---\left(2\right)$

$M-{\mathrm{bM}}_0=\frac{{\mathrm{GD}}_0^2+{\mathrm{GD}}_2^2}{375}{\left(\frac{d_n}{d_t}\right)}_3---\left(3\right)$

$-{\mathrm{bM}}_0=\frac{{\mathrm{GD}}_0^2+{\mathrm{GD}}_2^2}{375}{\left(\frac{d_n}{d_t}\right)}_4---\left(4\right)$

In formula, a, b are because increasing

(i=1,2) and make M ₀the coefficient increasing.

According to Electrical Motor principle, the motor of having got well for manufacture,

be a constant, in the time that terminal voltage is identical with temperature rise, its M-n family curve is unique, M ₀-n curve is also unique, can be because of not additional (i=1,2 ...) and change characteristic shape.That is to say, in above-mentioned each starting, stopped process, under identical rotation speed n, its corresponding M is identical, M ₀also identical.In above-mentioned Four processes, in the time that rotation speed n is identical, unknown number M, M in each equation ₀, represent respectively same numerical value, equation can simultaneous and is solved.Every corresponding rotation speed n, can obtain one group

set up a system of equations.This in dynamic process, to be set up for front topic with identical rotation speed n a series of system of equations.The present invention is called mobile equation group.Therefore, when establishing

$A_i=\frac{{\mathrm{<figure-callout\; id="1"\; label="GD"\; filenames="H85100389E0000051.png"\; state="\{\{state\}\}">GD</figure-callout>}}_1^2}{375}$ (i＝0，1，2，…)

$T_i={\left(\frac{d_n}{d_t}\right)}_i$ (i＝1，2，…)

By equation (1)～(4), obtain a mobile equation group:

$\left\{\begin{array}{c}M-{\mathrm{aM}}_0=(A_0+A_1)T_1\\ -{\mathrm{aM}}_0=(A_0+A_1)T_2\\ M-{\mathrm{bM}}_0=(A_0+A_2)T_3\\ -{\mathrm{bM}}_0=(A_0+A_2)T_4\end{array}\right.$

And solve: $A_0=\frac{A_1(T_2-T_1)+A_2(T_3-T_4)}{T_1-T_2-{\mathrm{<figure-callout\; id="3"\; label="T"\; filenames="H85100389E0000051.png"\; state="\{\{state\}\}">T</figure-callout>}}_3+T_4}$

$M=\frac{(A_2-A_1)(T_1-T_2)(T_3-T_4)}{T_1-T_2-{\mathrm{<figure-callout\; id="3"\; label="T"\; filenames="H85100389E0000051.png"\; state="\{\{state\}\}">T</figure-callout>}}_3+T_4}$

Make freely to stop once after the not additional fly wheel start-up of motor:

$-M_0=\frac{{\mathrm{GD}}_0^2}{375}{\left(\frac{d_n}{d_t}\right)}_5$

That is: M ₀=-A ₀t ₅

According to test needs, to selected a series of n values between synchronous rotational speed, can obtain corresponding M value, M at n=0 ₀value, records M-n curve and M _0-ncurve.According to Electrical Motor principle, in many occasions all M ₀regard a constant as, now, only need measure one time M ₀.In like manner,

also only need measure once.

This method select microsystem and speed probe carry out n and measurement.Because n is from 0 very wide to synchronous rotational speed variation range, the Measuring Frequency Method conventionally adopting and survey Zhou Fajun and can not guarantee precision.For this reason, the present invention has designed a kind of increasing pulse timing, and the rotation speed n that different moments of measuring and calculating are and n are with the rate of change of t the acceleration of motor is used as to uniform acceleration and treats, the overall process of each starting was divided equally for several sampling intervals by the time, the revolution turning in each interval is n _i;

$n_i=\frac{1}{2}{n}_0\&CenterDot;T_q\&CenterDot;\frac{2i-1}{P^2}$

N ₀---synchronous rotational speed

T _q---the starting time

I---i interval (i=1,2 ...)

P---interval number

To n _iround, obtain one and increase progressively pulse ordered series of numbers, the umber of pulse that each number of this ordered series of numbers is corresponding sampling interval, sends this pulse ordered series of numbers into microsystem, and microsystem counts, clocks, numbers, stores by this pulse ordered series of numbers.After all starting and stopping process completes, microcomputer takes out corresponding data automatically from storer, sets up mobile equation group and solves, and obtains the M value under different n, and M ₀value,

value, printing simultaneously or curve plotting, output.Native system completes said process all to be undertaken by the instruction that is solidificated in advance the software package in microcomputer.

For motor in starting process because terminal voltage changes the torque error causing, the present invention adopts voltage, current transducer and microcomputer automatically to compensate.

Apparatus of the present invention are: the standard flywheel (4) (accompanying drawing is only drawn two) of several different flywheel moments, be attached to respectively as required on tested motor (3) axle, and fix with bolt by flywheel sleeve (5) left end, flywheel sleeve (5) right-hand member is fixed with the axle of bolt and speed probe (6), and make on the same axis of axis and tested motor axis place, view sensor (6) pattern difference, also can not be connected with sleeve; Speed probe is inputted microsystem (8) by the motor speed signal recording by shielded cable (7); For revising voltage, the current transducer (2) and power switch (1) and tested motor in series of torque error, and connect with microsystem.

The inventive method and device can improve measuring accuracy, simplify test process, easy to operate, and in measuring torque M, obtain

and M ₀, be applicable to test the asynchronous motor of different capacity.

Embodiment:

Tested motor Y160,1500 revs/min.Flywheel is 310 two of φ 290 and φ, and speed probe is SZGB type photoelectric sensor, and microsystem is Z-80 type single card microcomputer and relevant peripherals.

Start-up time T _q=15 seconds, startup overall process is divided into 100 intervals, according to formula $N_i=\frac{1}{2}{n}_0\&CenterDot;T_q\&CenterDot;\frac{2i-1}{P^2}$ ${\mathrm{<figure-callout\; id="1"\; label="N"\; filenames="H85100389E0000051.png"\; state="\{\{state\}\}">N</figure-callout>}}_1=\frac{1.87}{100},$

$N_2=\frac{5.63}{100},$ ${\mathrm{<figure-callout\; id="3"\; label="n"\; filenames="H85100389E0000051.png"\; state="\{\{state\}\}">n</figure-callout>}}_3=\frac{9.38}{100},$ $N_{100}=\frac{373.0}{100}$

The umber of pulse that often transfers 100 pulses is: 1.87,5.63,9.38 ... 373.00.

After rounding, obtaining sampling interval umber of pulse is followed successively by: 2,6,9 ... 373, make microsystem sample by such pulse, record, processing, compensation, obtain M, M ₀, draw M-n curve.

Claims (2)

1. an induction motors torque---rotary speed property dynamic testing method, to make tested motor no-load starting, set up its no-load torque equation, and record tested motor speed with speed measuring device, by rotating speed to time diffusion, process, obtain torque---rotation speed characteristic also shows by display device, and the feature of the inventive method is: on tested motor reel, additional flywheel moment is respectively

flywheel, often an additional flywheel, makes motor do one push start and stop, and sets up two corresponding equations, under the condition of same rotational speed n, by equations simultaneousness, sets up mobile equation group:

$\left\{\begin{array}{c}M-{\mathrm{aM}}_0=\frac{{\mathrm{GD}}_0^2+{\mathrm{GD}}_1^2}{375}{\left(\frac{d_n}{d_t}\right)}_1\\ -{\mathrm{aM}}_0=\frac{{\mathrm{GD}}_0^2+{\mathrm{GD}}_1^2}{375}{\left(\frac{d_n}{d_t}\right)}_2\\ M-{\mathrm{bM}}_0=\frac{{\mathrm{GD}}_0^2+{\mathrm{GD}}_2^2}{375}{\left(\frac{d_n}{d_t}\right)}_3\\ -{\mathrm{bM}}_0=\frac{{\mathrm{GD}}_0^2+{\mathrm{GD}}_2^2}{375}{\left(\frac{d_n}{d_t}\right)}_4\\ \&CenterDot;\\ \&CenterDot;\\ \&CenterDot;\\ \&CenterDot;\end{array}\right.$

Starting overall process was divided equally for several sampling intervals by the time, calculate each interval revolution n _i, to n _iafter rounding one increase progressively pulse ordered series of numbers, the input of pulse ordered series of numbers is solidified with in advance to the microsystem of software package, adopt increasing pulse timing, by microsystem sample, counting, timing, storage, calculating

simultaneous solution system of equations, draws M-n curve, M ₀,

2. press the Special testing device of method of testing work claimed in claim 1 for one kind, it is characterized in that this device can be attached on motor reel, be had a flywheel (4) of different flywheel moments by several, flywheel sleeve (5), speed probe (6), microsystem (8) and voltage, current transducer (2) composition for correction torque.

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