TWI409486B - Measurement of motor parameters - Google Patents

Abstract

An electrical motor parameter measurement method comprises the following steps: (A) providing a power supply device electrically connected to an induction motor; (B) the power supply device supplying a driving power that is conducted to the induction motor to have the induction motor activated from resting to accelerating in a load-free manner to a steady state rotational speed and at the same time, detecting and recording an activation transient current and an activation transient voltage for the induction motor starting from resting to accelerating to the steady state rotational speed; (C) the power supply device cutting off the driving power to make the induction motor to decelerate from the steady state rotational speed to resting and at the same time detecting and recording a shutdown transient current and a shutdown transient voltage for the induction motor to naturally decelerate from the steady state rotational speed to resting; and (D) supplying the activation transient current, the activation transient voltage, the shutdown transient current, and the shutdown transient voltage to a computation system to carry out computation for obtaining parameters of the induction motor.

Description

Motor parameter measurement method

A method of measuring electrical parameters, in particular a method of measuring the parameters of an induction motor.

Induction motors have evolved over the years, and many types of induction motors have different output characteristics in order to make induction motors suitable for various machines. In order to ensure that the manufactured induction motor has the correct characteristics, it is necessary to understand the equivalent model of the induction motor on the circuit. For many years, there have been many academic studies on the equivalent circuit of the induction motor, which assists the manufacturer in measuring the induction motor. The data at the time of operation further derives the equivalent circuit type. Knowing more about the equivalent circuit type of the induction motor after power-on, you can further understand the characteristics and defects of the motor, and make an induction motor with more accurate output and more stability.

The known measurement method is the "Motor Electric Parameter Identification Method" of the Republic of China Patent Publication No. 298620, wherein the method comprises: (a) providing a motor; (b) providing an encoder for detecting the motor rotor (c) provides a motor basic vector control architecture for use as a vector control law to control the speed of the motor; (d) one of the inverters with a sinusoidal pulse width modulation (SPWM) function a power supply of the driven motor, wherein the microprocessor in the frequency converter is a digital control unit, and the digital control unit comprises a standard conversion block A, a standard conversion block B and a random random number generator; (e) The coordinate conversion block A is used to convert one of the stator current measurement values of the motor into a two-axis current component of a rotor magnetic field coordinate system (dq) axis; (f) the coordinate conversion block B is used to apply the rotor magnetic field The value of the d-axis stator voltage standard and the value of a q-axis stator voltage standard are converted into values of one of the three-phase input voltage targets of a sinusoidal pulse width modulation (SPWM) inverter; (g) the rotor magnetic field The q-axis voltage on the coordinates A value of zero, at which point the fan motor is stationary, and wherein a target value based rotor flux angle is any value; (H) The random number generator randomly Used Generating a value of the d-axis stator voltage on the axis of the rotor magnetic field coordinate system (dq); (i) causing the digital control unit in the frequency converter that drives the motor to sample and record the rotor magnetic field coordinates at a sampling time The d-axis voltage target value and the d-axis output current; and (j) automatically derive the estimated value of each motor electrical parameter by the dynamic mathematical equation of the motor.

It can be known from the technical content of the prior case No. 298620 that the method needs to use a certain amount of sub-current and the value of the d-axis stator voltage target and a value of a q-axis stator voltage target to be converted into an input sine wave pulse width modulation (SPWM) inverse. One of the three phase input voltage values of the phaser. The motor is again in a stationary state, and the value of the rotor flux angle is measured. A value of the d-axis stator voltage on the axis of the rotor magnetic field coordinate system (d-q) is generated using a random random number generator. Finally, the digital control unit in the inverter driving the motor samples at a sampling time and records the value of the d-axis voltage target and the d-axis output current on the rotor magnetic field coordinate. The electrical parameters of the motor are obtained through numerous complicated measurements and calculations.

The Republic of China Patent Publication No. 485248 discloses a motor electrical automatic parameter identification method, the method steps of which generally include: a) providing a motor; b) providing an inverter to drive the motor, the frequency converter including space vector modulation Current controller, vector controller; c) control inverter output motor one phase terminal is DC power supply positive terminal, the other two phases are DC power supply negative pole to complete DC test; d) control inverter input motor phase The terminal is the positive pole of the single-phase AC power supply, the other two phases are the negative pole of the single-phase AC power supply, and the rotor test is completed; e) the motor is unloaded and the inverter is input to the three-phase rated frequency of the motor or various AC power sources. The motor can be rotated at a synchronous number close to the input frequency to complete the no-load test; f) The estimated value of each motor electrical parameter is derived from the dynamic mathematical equation of the motor through three tests. The previous case must pass three different tests, and the measurement process is equally cumbersome, and the electrical parameters of the motor cannot be obtained quickly and easily.

In addition to the two previous cases mentioned above, other induction motor measurement methods such as the Republic of China Patent Publication Nos. 544524, No. 565992, and No. I227331, the previously created test methods are equally complicated, and the biggest drawback is inconvenient. In line with actual needs, Online measurement is performed directly in the workplace where the induction motor operates. Moreover, the biggest missing of the above-mentioned stall test is that the temperature effect needs to be considered, which makes the test process more complicated and cumbersome. The general user (operator in the factory) cannot measure it by himself, so it is often measured by the manufacturer when the induction motor is manufactured. . However, after many industrial procedures, the electrical conductivity of the rotor will be affected, and its correctness cannot be trusted.

In addition, an AC power line impedance test method is described in "IEEE TRANSACTIONS ON INDUSTRY APPLICATION VOL.44 NO.4.JULY/AUGUST 2008" on pages 1034~1037 (please refer to Annex 1). Section III of this publication (III. NOVEL MEASUREMENT SCHEME) discloses a test method that includes the measurement circuit used and the steps of the test, while the test steps take three different time points: the line at no load. The voltage peak value Vo, the line voltage peak value Vr at the time of the load, and the wavelength of the first half period on the LC resonance loop. In order to obtain the above parameters, the document uses a switching element SW to obtain parameters of different time points by turning on or off, and obtaining the equivalent impedance of the circuit through derivation of the formula.

It can be seen from the foregoing prior art that, in order to obtain the complete parameters of the induction motor, it is necessary to rely on the external detection device or the control circuit, which requires measurement of multiple steps, which is too complicated.

Furthermore, industrial induction motors have a large volume and weight, and it is not easy to move the induction motor, and professional measuring equipment and computer equipment are also inconvenient to move. Therefore, in practice, the aforementioned prior patents are difficult to apply to on-site measurements. In the case that the parameters of the induction motor cannot be easily measured, the operator in the factory can only know some parameters of the induction motor according to the nameplate of the induction motor, and cannot measure the actual performance of the induction motor after starting. Since it is impossible to directly measure the parameters of the induction motor on the factory line, it is impossible to know the wear state of the induction motor after use.

Industrial induction motors are not easy to move due to their size and weight, and are not easy to move to Measurements are taken in the laboratory. Furthermore, conventional measurement techniques require the use of tachometers, frequency converters, vector controllers, etc., which are also inconvenient to carry or move, and must be reconnected to the power line of the induction motor when making measurements, resulting in The inconvenience of measurement. Therefore, the object of the present invention is to provide a measurement method which is advantageous in that the measurement method and the required equipment are simplified, and the measurement is directly performed on the operation line of the induction motor.

The present invention relates to a method for measuring motor parameters, comprising the steps of: A) providing a power supply device electrically connected to an induction motor; B) providing a driving power to the induction motor to cause the induction motor to be unloaded. The stationary start accelerates to a steady state speed, and detects and records a start transient current and a start transient voltage when the induction motor accelerates from the stationary start to the steady state speed; C) the power supply device stops providing the drive power Having the induction motor decelerate from the steady state speed to a standstill, and simultaneously detecting and recording a shutdown transient current and a shutdown transient voltage when the induction motor is naturally decelerated from the steady state speed to a stationary start; D) providing the start The transient current, the starting transient voltage, the shutdown transient current, and the shutdown transient voltage are applied to an arithmetic system to obtain the parameters of the induction motor.

The main difference between this case and the known case is that the case detects the current and voltage values of the induction motor during the period from the start to the steady speed, and the current and voltage during the period when the rotation speed is stable and the power is naturally decelerated to stop. Value. Through the above-mentioned detected current and voltage values, the single-phase equivalent reactance, rotor equivalent resistance, stator equivalent reactance, rotor equivalent reactance, slip ratio, air gap power, and output torque of the induction motor can be further obtained. Any one or more of the friction coefficient, the rotor speed, the equivalent magnetization inductance, and the induction inertia. This makes it quick and easy to understand the characteristics of each induction motor. Once you know the exact parameters of the induction motor itself, you can assist the user to compare the measured parameters with the factory calibration parameters to confirm the life loss of the induction motor itself or whether there are structural defects. Further, the operator can set the control circuit according to the actual parameters of the induction motor, so that the output of the induction motor is more in line with the actual needs of the operator, and even the output curve of the induction motor can be changed to be applied to different working requirements.

This case is a measurement method of the motor parameters. The technical content of the present case will be described below with reference to the drawings.

Please refer to FIG. 1 , which is a schematic flow chart of an embodiment of the present invention. As shown in the figure, the measurement method disclosed in the present invention includes the following steps: A. providing a power supply device to electrically connect an induction motor. B. The power supply device outputs a driving power to the induction motor to accelerate the self-stopping of the induction motor to a steady state speed (as shown in step S1 of FIG. 1), and simultaneously detects and records the induction motor. The stationary start accelerates to a start transient current and a start transient voltage at the steady state speed (as shown in step S2 of FIG. 1). C. The power supply device stops outputting the driving power, causing the induction motor to decelerate from the steady state speed to a standstill, and simultaneously detecting and recording a shutdown transient current of the induction motor from the steady state rotation to the stationary start state Turn off the transient voltage (as shown in step S3 of Figure 1). D. Providing the startup transient current, the startup transient voltage, the shutdown transient current, and the shutdown transient voltage to an arithmetic system to calculate the parameters of the induction motor (as shown in step S4 of FIG. 1).

In addition, referring to FIG. 2, it is a schematic diagram of a circuit architecture for implementing the foregoing steps. The circuit architecture includes a power supply device, and the power supply device provides a power distribution board electrically connected to a power source 20. 3, the switchboard 3 has a three-phase power supply line 31 electrically connected to a three-phase bus bar 2, the three-phase bus bar 2 is electrically connected to a power source 20 to provide a three-phase power as a driving power to drive an induction motor 1. The three-phase power supply line 31 is provided with a circuit breaker 33, and the rear end of the circuit breaker 33 is connected to an induction motor 1. A shunt line 32 is connected between the power source 20 and the circuit breaker 33. The shunt line 32 is used to implement the starting transient current and the shutdown transient current in the steps B and C. The voltage dividing circuit 35 is electrically connected between the circuit breaker 33 and the induction motor 1, and the voltage dividing circuit 35 obtains the starting transient voltage and the shutdown transient voltage by performing the foregoing steps B and C. The shunt line 32 further includes a coupling to the three phases for A current divider 320 on the electrical line 31; the voltage dividing circuit 35 includes a voltage divider 350 coupled to the three-phase power supply line 31. The shunt line 32 and the voltage dividing line 35 obtain current and voltage values from the three-phase power supply line 31, and are respectively connected to a detecting and recording unit 4 to transmit current and voltage values to the detecting and recording unit 4. The voltage comparator 350 is selectively coupled to a surge absorber 34 to absorb power surges on the three-phase supply line 31. The three-phase power supply line 31 further selects a three-phase comparator 36 on the three-phase power supply line 31 in parallel, and the three-phase comparator 36 is electrically connected to each phase line, and is composed of a single comparator 361. The single comparator 361 can only provide a voltage value for the no-load start, and the comparator 350 can fully record the start and stop voltage values. The aforementioned detection and recording unit 4 is further connected to an arithmetic system 5.

At the beginning of the measurement, the switchboard 3 provides a driving power through the three-phase power supply line 31 to accelerate the self-stationary start of the induction motor 1 to a steady state speed (as shown in block S1 of FIG. 1), which is a start-up period. . During the period of time, the detecting and recording unit 4 detects and records a starting transient current of the induction motor 1 from the stationary start to the steady state speed through the shunt line 32 and the voltage dividing line 35. Start the transient voltage (as shown in block S2 of Figure 1). At this time, the detecting and recording unit 4 can record the current and voltage changes when the induction motor 1 is started to the steady state speed. Next, the supply of the driving power to the induction motor 1 at the steady-state rotational speed is stopped, and the induction motor 1 is naturally decelerated from the steady-state rotational speed to be stationary (as shown in a block S3 of Fig. 1). During the shutdown of the induction motor 1, the detecting and recording unit 4 detects and records a shutdown transient current and a shutdown transient voltage of the induction motor 1 from the steady state rotation to the stationary start. 1 block S4). Finally, the detecting and recording unit 4 provides the recorded transient current, the starting transient voltage, the shutdown transient current and the shutdown transient voltage to the computing system 5 to obtain the parameters of the induction motor 1 (as shown in the figure). 1 block S5).

The computing system 5 obtains the single-phase equivalent reactance, the rotor equivalent resistance, the stator equivalent reactance, the rotor equivalent reactance, the slip ratio, and the air gap of the induction motor 1 through a known arithmetic expression. Any one or more of power, output torque, friction coefficient, rotor speed, equivalent magnetizing inductance, and induction inertia.

For example, the transient voltage v _s ( t ) and the current i _s ( t ) of the single-phase start and shutdown of the input of the induction motor 1 can be obtained by a known formula: voltage: v ( t ) = V _m sin ( ωt ) current: i ( t ) = I _m sin( ωt - θ ₁ )

In the absence of harmonic interference, the positive and cosine components of the voltage are v ₁ ( t ) and v ₂ ( t ): v ₁ ( t )= v ( t )= V _m sin( ωt ) v _{2( t )} = v ( t +90°)= V _m sin( ωt +90°)= V _m cos( ωt )

The positive and cosine components of the current are i ₁ ( t ) and i ₂ ( t ): i ₁ ( t ) = i ( t ) = I _m sin( ωt ) i ₂ ( t ) = i ( t +90°) = I _m sin( ωt - θ ₁ +90°) = I _m cos( ωt - θ ₁ )

Real power:

Virtual power:

Obtain a single-phase voltage V _m , a voltage frequency f , a current root mean square (RMS) value I _rms , and a real work by a conventional measuring instrument operation. Virtual work .

Voltage: v ( t )= V _m sin( ωt )= V _m sin(2 πft )

The positive and cosine components are: v ₁ ( t )= V _m sin(2 πft ) v ₂ ( t )= V _m cos(2 πft )

Where the amplitude V _m is:

Differentiating the aforementioned positive and cosine components can obtain:

The frequency of sorting the above expressions is:

Further, using single-phase real work , can get single-phase equivalent resistance:

Single-phase equivalent reactance can be obtained by using single-phase virtual work.

The rotor equivalent resistance can be obtained at the beginning of induction motor 1: R _r '= R _eq - R _s

Stator, rotor equivalent reactance:

The slip rate from the initial stage to the steady speed is: s ₁ = P, and ω _{r 1} ( t ) can be further obtained.

Using single-phase real work With the single-phase current I _{s at the} stator end, the air gap power P _G in the former equation can be obtained:

Using the air gap power P _G , the output torque of the induction motor 1 can be obtained:

Using the output torque τ _ind and the rotor angular velocity ω _{r 0} , the friction coefficient can be obtained:

Using the frequency f , the rotor speed after the switch is turned on:

After V _m × ω _s / ω _{r 2} ( t ) is attenuated to The time t _{2 is} the time constant τ and the equivalent magnetizing inductance is:

When ω _{r 2} ( t ) is attenuated to ω _{r 0} e ^-1 , time t _{2 is} the time constant τ , and the inertia of the motor-driven machine 1 is: J = τ _r F

Correction factor k :

Correct the slip to: s _{1 k} = k ² × s ₁

Further corrected rotor speed ω _{1 k} ( t )=(1- s _{1 k} ) ω _s

Therefore, as long as the above steps provided in this case are used to obtain the startup transient current, start the temporary After the state voltage, the shutdown transient current and the shutdown transient voltage, the important parameters of the operation of the induction motor 1 can be further calculated, which is convenient for the operator to control the induction motor 1, and further contributes to the development and improvement of the induction motor 1.

The method is mainly for the induction motor 1 to receive a driving power start under no-load condition, and the induction motor 1 detects and records a starting transient current and a starting temporary period from the stationary starting acceleration to a steady-state rotating speed. State voltage. Then, the driving power is stopped, the induction motor 1 is naturally decelerated to a standstill, and a shutdown transient current and a shutdown transient voltage are detected and recorded during the steady state speed deceleration to a standstill. The induction motor parameters are obtained by using the startup transient current, the starting transient voltage, the shutdown transient current, and the shutdown transient voltage calculation. In the conventional measurement method, no prior art has been used to calculate the parameter values using the current and voltage values during the start and stop periods. Furthermore, in the foregoing steps of the present invention, it is not necessary to use a frequency converter to control the operation of the induction motor 1, and it is not necessary to adjust the maximum rotation speed or torque of the induction motor 1 in order to achieve a certain state. The induction motor 1 starts to operate to perform the measurement step. Thereby, the characteristics of each induction motor 1 can be quickly and easily understood. Once the actual parameters of the induction motor 1 are known, the user can be assisted in comparing the measured parameters with the factory calibration parameters to confirm the life loss of the induction motor 1 itself or whether there is a structural defect. Further, the operator can set the control circuit according to the actual parameters of the induction motor 1, so that the output of the induction motor 1 more closely meets the actual needs of the operator, and even the output curve of the induction motor 1 can be changed to be applied to different Work needs.

Although the present invention has been disclosed above in the preferred embodiment, it is not intended to limit the present invention. Anyone who is familiar with this skill and does not deviate from the spirit and scope of this case, and some of the changes and refinements should be covered in this case. Therefore, the scope of protection of this case is subject to the definition of the patent application scope attached.

In summary, this case enhances the above-mentioned effects compared with the customary creations, and should fully comply with the statutory innovation patent requirements of novelty and progressiveness, and apply in accordance with the law, please ask your office. Approved this invention patent application, in order to encourage creation, to the sense of virtue.

1‧‧‧Induction motor

2‧‧‧Three-phase busbar

20‧‧‧Power source

3‧‧‧Distribution panel

31‧‧‧Three-phase power supply line

32‧‧‧Split line

320‧‧‧ current comparator

33‧‧‧Circuit breaker

34‧‧‧ surge absorber

35‧‧‧voltage line

350‧‧‧ Comparator

36‧‧‧Three comparators

361‧‧‧Single pressure comparator

4‧‧‧Detection and Recording Unit

5‧‧‧ computing system

S1~S5‧‧‧Steps

FIG. 1 is a schematic flow chart showing the steps of an embodiment of a method for measuring motor parameters of the present invention.

2 is a schematic diagram of a circuit architecture for measuring the motor parameters of the present invention for implementing the foregoing steps.

S1~S5‧‧‧Steps

Claims (11)

A method for measuring motor parameters includes the steps of: A. providing an induction motor electrically connected to a power supply device; B. providing a drive power to the induction motor to accelerate the self-stationary start of the induction motor to no load a steady state speed, simultaneously detecting and recording a starting transient current and a starting transient voltage when the induction motor accelerates from a stationary start to the steady state speed; C. the power supply device stops providing the driving power to the induction motor Decelerating from the steady-state speed to a standstill, simultaneously detecting and recording a shutdown transient current and a shutdown transient voltage when the induction motor is naturally decelerated from the steady-state speed to a stationary start; and D. providing the startup transient current And starting the transient voltage, turning off the transient current and turning off the transient voltage to an arithmetic system to calculate the parameters of the induction motor. The method for measuring a motor parameter according to claim 1, wherein the power supply device provides a switchboard electrically connected to a power source, the switchboard provides a three-phase power to drive the induction motor, and the three-phase There is a circuit breaker on the power supply line of the power. The method for measuring a motor parameter as described in claim 2, wherein in step B and step C, the starting transient current and the shutdown transient are respectively obtained from a line between the power source and the circuit breaker. Current. The method for measuring a motor parameter according to claim 2, wherein in step B and step C, the starting transient voltage and the shutdown transient are respectively obtained from a line between the circuit breaker and the induction motor. Voltage. The method for measuring a motor parameter as described in claim 2, wherein the line between the power source and the circuit breaker is electrically connected to a shunt line, and the other end of the shunt line is electrically connected to the computing system. The method for measuring a motor parameter according to claim 5, wherein a detecting and recording unit is disposed between the computing system and the shunt line. A method of measuring a motor parameter as recited in claim 5, wherein the shunt line comprises a current transformer coupled to the switchboard line. The method for measuring a motor parameter according to the second aspect of the invention, wherein the circuit between the circuit breaker and the induction motor is electrically connected to a voltage dividing circuit, and the other end of the voltage dividing circuit is electrically connected to the operation. system. The method for measuring a motor parameter according to claim 8, wherein a detecting and recording unit is disposed between the computing system and the voltage dividing circuit. The method for measuring a motor parameter according to claim 8, wherein the voltage dividing circuit comprises a voltage comparator connected in parallel to the circuit of the power strip. The method for measuring a motor as described in claim 1, wherein the parameters of the induction motor include a single phase equivalent reactance, a rotor equivalent resistance, a stator equivalent reactance, a rotor equivalent reactance, a slip ratio, and a gas. Any one or more of the gap power, output torque, friction coefficient, rotor speed, equivalent magnetizing inductance, and induction inertia.