CN102374924A - Measurement method of moment of inertia of separately excited DC (Direct Current) motor - Google Patents

Abstract

The invention belongs to the motor parameter measurement technology, and relates to an improvement of a measurement method of the moment of inertia of a separately excited DC (Direct Current) motor based on a Siemens 6RA70 series all-digital DC speed control device. The measurement method is characterized by comprising the following steps that: a measured motor is connected; an acceleration time Ta is measured; and the moment of inertia J is calculated. The measurement method provided by the invention is simple and convenient to operate, is suitable for being used in engineering application sites, has strong engineering practicality, and meets the need of debugging of a DC transmission system.

Description

A kind of measuring method of separately excited DC machine moment of inertia

Technical field

The invention belongs to parameter of electric machine measuring technique, relate to improvement the separately excited DC machine method for measuring rotary inertia.

Background technology

In the DC electrical driving control system, the moment of inertia of direct current motor and gear case is very big to the influence of system dynamics response time, in quick response system, requires moment of inertia more little good more.Direct current generator manufacturer is not owing to test the specialized equipment of moment of inertia, and the data of often can not giving actual rotation inertia can only provide the Design Theory data.Some producer even couple very much in love opinion data do not provide yet.In the direct current fax system debug process, whether the actual inertia that need know motor and gear case within the designing requirement scope, if excessive, need add the moment of inertia compensation in controlling unit.GB1311 " direct current generator test method " provides three kinds of assay methods of motor moment of inertia J: from retardation method, rock method and auxiliary pendulum method.

1) be the free parking method from retardation method, at first will measure open-circuit core loss and the mechanical loss of motor when rated speed, rated exciting current be higher than rated speed n _NUnder do no-load running, treat that the motor back of operating steadily cuts off rapidly the armature power supply, slow down naturally by its inertia, use the oscillograph recording deceleration curve, analytic curve substitution formula calculating J.

2) method of rocking is the method that compares by the moment of inertia of the moment of inertia of examination rotor and cylindrical standard rotor.Need rotor taken out and hang on the support, measure hunting period, but also will make the false rotor that a quality, diameter that diameter is close with true rotor are calculated inertia, test the false rotor swing cycle under the same conditions, again substitution calculating J.

3) auxiliary pendulum method is fixed in tested machine shaft end face center with a known auxiliary pendulum of quality with the as far as possible little armed lever of quality, asks mean value hunting period, and the substitution formula calculates J.

These three kinds of methods are all cumbersome, and only suitable motor performance detects unit or research unit uses, and are not suitable for the on-the-spot use of practical applications.

Summary of the invention

The objective of the invention is: propose the on-the-spot separately excited DC machine method for measuring rotary inertia that uses of a kind of practical applications easy and simple to handle, suitable, to satisfy the needs of direct current fax system debug.

Technical scheme of the present invention is: a kind of measuring method of separately excited DC machine moment of inertia based on Siemens 6RA70 series digital direct current speeder, is characterized in that the step of measurement is following:

1, connects by measured motor: will be fixed on the measuring table by measured motor, and when needs are measured the total moment of inertia under the motor bringing onto load state, also need and to be connected with load by measured motor; Be connected with armature, the excitation output terminal of Siemens 6RA70 series digital direct current speeder through armature, the excitation terminals of cable then motor;

2, measure acceleration time Ta: give the energising of Siemens 6RA70 series digital direct current speeder; The method of operation is set to " friction and moment of inertia compensation optimizing " method of operation, measures the acceleration time Ta that is accelerated to rated speed by measured motor with rated current and rated exciting current from zero-speed;

3, calculate moment of inertia J: according to computes by the moment of inertia J of measured motor:

$J=\frac{91358\mathrm{kPTa}}{N^2}---\left[1\right]$

In the formula, P is a direct current generator rated power, and unit is kW; Ta unit is s; N is the motor rated speed, and unit is r/min; K is a correction factor, and definite method of coefficient k is:

$k=\frac{\mathrm{Ib}}{\mathrm{Ia}}---\left[2\right]$

In the formula, Ib is the actual output-current rating of Siemens 6RA70 series digital direct current speeder, and Ia is the armature rated current of tested motor nameplate mark, and unit is A.

Advantage of the present invention is: easy and simple to handle, be fit to the on-the-spot use of practical applications, and engineering practicability is strong, has satisfied the needs of direct current fax system debug.

Description of drawings

Fig. 1 instrumentation plan of the present invention.

Embodiment

Explain further details in the face of the present invention down.Referring to Fig. 1, a kind of measuring method of separately excited DC machine moment of inertia, is characterized in that the concrete steps of measurement are following based on Siemens 6RA70 series digital direct current speeder (hereinafter to be referred as arrangements for speed regulation):

1, connects by measured motor: will be fixed on the measuring table by measured motor, and when needs are measured the total moment of inertia under the motor bringing onto load state, also need and to be connected with load by measured motor; Be connected with armature, the excitation output terminal of arrangements for speed regulation through armature, the excitation terminals of cable then motor;

2, measure acceleration time Ta: switch on to arrangements for speed regulation; The method of operation is set to " friction and moment of inertia compensation optimizing " method of operation; Measure the acceleration time Ta that is accelerated to rated speed by measured motor with rated current and rated exciting current from zero-speed; The Ta respective value is an arrangements for speed regulation inner parameter P540 video data, and unit is s;

3, calculate moment of inertia J: according to computes by the moment of inertia J of measured motor:

$J=\frac{91358\mathrm{kPTa}}{N^2}---\left[1\right]$

In the formula, P is a direct current generator rated power, and unit is kW; Ta unit is s; N is the motor rated speed, and unit is r/min; K is a correction factor, and definite method of coefficient k is:

$k=\frac{\mathrm{Ib}}{\mathrm{Ia}}---\left[2\right]$

In the formula, Ib is the actual output-current rating of arrangements for speed regulation, and Ia is the armature rated current of tested motor nameplate mark, and unit is A.

Principle of work of the present invention is: the calculating formula process is following:

Acceleration time Ta:

$\mathrm{Ta}=\frac{4\mathrm{gJ\ΔN}}{375\mathrm{\ΔM}}---\left[3\right]$

In the formula, g is a constant 9.8; J is a moment of inertia, and unit is kgm ²Δ N is an acceleration range, and unit is r/min; Δ M is the motor acceleration torque, and unit is Nm.

Motor nominal torque M:

$M=\frac{9550P}{N}---\left[4\right]$

In the formula, P is a motor rated power, and unit is kW; N is the motor rated speed, and unit is r/min.

Introduce correction factor k, derive the calculating formula of moment of inertia J by [3] formula, [4] formula:

$J=k\frac{375\mathrm{MTa}}{4\mathrm{gN}}=\frac{91358\mathrm{kPTa}}{N^2}---\left[1\right]$

In the formula, P is tested motor rated power, and unit is kW; Ta is the acceleration time, and unit is s; N is the motor rated speed, and unit is r/min; K is a correction factor, and value is the actual output-current rating of tested motor speed control device and the ratio of tested armature rated current.

Embodiments of the invention: in certain aeroengine control system semi-physical simulation device; The supporting arrangements for speed regulation of separately excited DC machine are Siemens 6RA70 series direct current speeder in the electric drive system; Through the measurement to direct current generator acceleration time (Ta=P540) of many different capacities, rotating speed, result of calculation is seen table 1.

Separately excited DC machine in the table 1 is varied; The miniwatt high speed DC slotless motor that customization is arranged; Have Nan Yang, Shanghai motor in high-power Z4 direct current generator; According to the national standard that motor is made, the moment of inertia design load that producer provides has ± 10% error, and the moment of inertia value of measuring according to the inventive method and the gap of motor producer design load are all in ± 10% scope; Check motor actual rotation inertia to satisfy user demand, embodied easy, effective, the practical advantage of this method.

The rotation inerttia result of 4 embodiment of table 1 the present invention

Error in the table 1 is meant the measured value of employing the inventive method and the gap of electrical machinery plant's design load.

Claims (1)

1. the measuring method of a separately excited DC machine moment of inertia based on Siemens 6RA70 series digital direct current speeder, is characterized in that the step of measurement is following:

1.1, connect by measured motor: will be fixed on the measuring table by measured motor, when needs are measured the following total moment of inertia of motor bringing onto load state, also needs will be connected with load by measured motor; Be connected with armature, the excitation output terminal of Siemens 6RA70 series digital direct current speeder through armature, the excitation terminals of cable then motor;

1.2, measure acceleration time Ta: give the energising of Siemens 6RA70 series digital direct current speeder; The method of operation is set to " friction and moment of inertia compensation optimizing " method of operation, measures the acceleration time Ta that is accelerated to rated speed by measured motor with rated current and rated exciting current from zero-speed;

1.3, calculate moment of inertia J: according to computes by the moment of inertia J of measured motor:

$J=\frac{91358\mathrm{kPTa}}{N^2}---\left[1\right]$

In the formula, P is a direct current generator rated power, and unit is kW; Ta unit is s; N is the motor rated speed, and unit is r/min; K is a correction factor, and definite method of coefficient k is:

$k=\frac{\mathrm{Ib}}{\mathrm{Ia}}---\left[2\right]$

In the formula, Ib is the actual output-current rating of Siemens 6RA70 series digital direct current speeder, and Ia is the armature rated current of tested motor nameplate mark, and unit is A.

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