CN110646730A - Method for estimating electromechanical time constant of motor - Google Patents

Abstract

The invention belongs to the field of motor characteristic testing, and particularly relates to a method for estimating an electromechanical time constant of a motor. It includes: the method comprises the following steps: testing and recording, namely applying rated voltage to a motor armature, acquiring the rotation angle and time of the motor through an electromagnetic striking timer, and recording for four times; step two: establishing a relational expression; step three: solving and calculating, and solving t by taking variance as an optimal target_{Starting up}And step four: calculating the electrical time constant tau, according to the formula tau being 0.7t_{Starting up}And obtaining the electromechanical time constant. The invention has the beneficial effects that: the electromechanical time constant of the motor is estimated through the rotation angle and time of the motor, high-precision current testing equipment is not needed, the motion process of the motor is not needed to be recorded, the operation is simple, and the method has better guiding significance for simple estimation of the electromechanical time constant of the motor.

Description

Method for estimating electromechanical time constant of motor

Technical Field

The invention belongs to the field of motor characteristic testing, and particularly relates to a method for estimating an electromechanical time constant of a motor.

Background

The electromechanical time constant of the motor is an important parameter index of the motor. Before assembly and use, the electromechanical time constant of the motor is often required to be tested separately so as to ensure that the system index requirements are met.

Generally, the electromechanical time constant test method is a current method, namely, after rated voltage is applied to a motor armature, the test current is increased from 0 to the maximum value and then is decreased to a current value I_TThe time required. The method depends on high-precision current testing equipment, the measured current data is often high in noise, and particularly for a micro motor, the measurement error is large.

Disclosure of Invention

The invention aims to provide a method for estimating an electromechanical time constant of a motor aiming at the defects of the prior art.

The invention is realized by the following steps: a method of estimating an electromechanical time constant of an electric machine, comprising the steps of:

the method comprises the following steps: testing and recording

Applying rated voltage to motor armature, obtaining motor rotation angle and time by electromagnetic striking timer, recording for four times, respectively recording psi_{General 1}、ψ_{General 2}、ψ_{Total 3}、ψ_{Total 4}、t _{General 1}、t_{General 2}、t_{Total 3}、t_{Total 4}，

Step two: establishing a relational expression

v_m1＝(ψ_{General 1}-ψ_{Starting up}-ψ_{Braking device})/(t_{General 1}-t_{Starting up}-t_{Braking device})≈

v_m2＝(ψ_{General 2}-ψ_{Starting up}-ψ_{Braking device})/(t_{General 2}-t_{Starting up}-t_{Braking device})≈

v_m3＝(ψ_{Total 3}-ψ_{Starting up}-ψ_{Braking device})/(t_{Total 3}-t_{Starting up}-t_{Braking device})≈

v_m4＝(ψ_{Total 4}-ψ_{Starting up}-ψ_{Braking device})/(t_{Total 4}-t_{Starting up}-t_{Braking device})

Step three: solving and calculating

By varianceSolving for t for an optimal target_{Starting up}Wherein, in the step (A),

step four: computer electrical time constant τ

According to the formula tau 0.7t_{Starting up}And obtaining the electromechanical time constant.

The invention has the beneficial effects that: the electromechanical time constant of the motor is estimated through the rotation angle and time of the motor, high-precision current testing equipment is not needed, the motion process of the motor is not needed to be recorded, the operation is simple, and the method has better guiding significance for simple estimation of the electromechanical time constant of the motor.

Drawings

Fig. 1 is a motor motion process curve.

Detailed Description

A method of estimating an electromechanical time constant of an electric machine, comprising the steps of:

1) testing and recording, acquiring a corner and required time, and repeating for multiple times;

2) analyzing and simplifying, and establishing a relational expression simultaneously;

3) solving and calculating to solve the starting process time of the motor;

4) the electromechanical time constant τ is calculated from empirical formulas.

In the step 1), rated voltage is applied to a motor armature for a period of time, the rotation angle and time of the motor are obtained through an electromagnetic striking timer, the test is repeated for multiple times, and psi is recorded_{General 1}、ψ_{General 2}、ψ_{Total 3}、ψ_{Total 4}、t_{General 1}、t_{General 2}、t_{Total 3}、t_{Total 4}。

In the step 2), the motor motion process can be divided into a starting process, a steady-state process and a braking process, and the angle psi of each motor starting process is assumed_{Starting up}And time t_{Starting up}Angle psi of braking process_{Braking device}And time t_{Braking device}According to the constant applied voltage, the steady speed v of the motor_mSubstantially equal, one can list:

v_m1＝(ψ_{general 1}-ψ_{Starting up}-ψ_{Braking device})/(t_{General 1}-t_{Starting up}-t_{Braking device})≈

v_m2＝(ψ_{General 2}-ψ_{Starting up}-ψ_{Braking device})/(t_{General 2}-t_{Starting up}-t_{Braking device})≈

v_m3＝(ψ_{Total 3}-ψ_{Starting up}-ψ_{Braking device})/(t_{Total 3}-t_{Starting up}-t_{Braking device})≈

v_m4＝(ψ_{Total 4}-ψ_{Starting up}-ψ_{Braking device})/(t_{Total 4}-t_{Starting up}-t_{Braking device})

In the step 3), because of errors of control, measurement and the like, the motor steady-state speed v obtained by each actual test_mThere is a certain deviation, therefore, the variance

Solving for t for an optimal target_{Starting up}Wherein, in the step (A),

in the step 4), the empirical formula τ is 0.7t_{Starting up}And obtaining the electromechanical time constant.

The invention is further described with reference to the following figures and specific embodiments.

As shown in fig. 1, taking an ultrasonic motor as an example, each motor movement process can be divided into a starting process, a steady-state process and a braking process, and taking a certain test as an example, the data is recorded as shown in table 1.

TABLE 1 Experimental records

Then it can be obtained: v. of_m＝(0.918-ψ_{Starting up}-ψ_{Braking device})/(3.267-t_{Starting up}-t_{Braking device})

≈(1.782-ψ_{Starting up}-ψ_{Braking device})/(6.500t_{Starting up}-t_{Braking device})

≈(3.618-ψ_{Starting up}-ψ_{Braking device})/(13.433-t_{Starting up}-t_{Braking device})

≈(7.231-ψ_{Starting up}-ψ_{Braking device})/(28.524-t_{Starting up}-t_{Braking device})

By variance

For the optimal target, t is solved_{Starting up}＝1.2ms。

According to an empirical formula, the electromechanical time constant τ is obtained to be 0.87 ms.

In addition, the electromechanical time constant obtained by the system identification curve fitting is 0.95ms, and the comparison shows that the electromechanical time constant estimation method provided by the invention is reliable and simple to operate.

Claims (1)

1. A method of estimating an electromechanical time constant of an electric machine, comprising the steps of:

the method comprises the following steps: testing and recording

Applying rated voltage to motor armature, obtaining motor rotation angle and time by electromagnetic striking timer, recording for four times, respectively recording psi_{General 1}、ψ_{General 2}、ψ_{Total 3}、ψ_{Total 4}、t _{General 1}、t_{General 2}、t_{Total 3}、t_{Total 4}，

Step two: establishing a relational expression

v_m1＝(ψ_{General 1}-ψ_{Starting up}-ψ_{Braking device})/(t_{General 1}-t_{Starting up}-t_{Braking device})≈

v_m2＝(ψ_{General 2}-ψ_{Starting up}-ψ_{Braking device})/(t_{General 2}-t_{Starting up}-t_{Braking device})≈

v_m3＝(ψ_{Total 3}-ψ_{Starting up}-ψ_{Braking device})/(t_{Total 3}-t_{Starting up}-t_{Braking device})≈

v_m4＝(ψ_{Total 4}-ψ_{Starting up}-ψ_{Braking device})/(t_{Total 4}-t_{Starting up}-t_{Braking device})

Step three: solving and calculating

By variance

Solving for t for an optimal target_{Starting up}Wherein, in the step (A),

step four: computer electrical time constant τ

According to the formula tau 0.7t_{Starting up}And obtaining the electromechanical time constant.