JP2011526233A - How to set the speed loop of a variable speed drive - Google Patents

Abstract

The present invention relates to a method for setting a speed adjustment loop of a speed variator designed to control a motor connected to a lifting load. The method depends on the nominal linear velocity of the load, the nominal rotational frequency of the motor, the number of motor pole pairs, and the total mass of the load, and the proportional gain (K _p ) and integral gain (K _I ) of the speed regulation loop. The step of calculating is included.

Description

  The present invention relates to a method for setting a speed regulation loop of a variable speed drive that controls a lifting load, in particular a synchronous or asynchronous electric motor designed to drive an elevator car.

  In order to control an electric motor, a variable speed drive typically includes a control system having an adjustment loop for adjusting the motor speed and an adjustment loop for adjusting the current delivered to the various phases of the motor. In lifting applications, particularly in elevators, it is particularly important to properly set the current regulation loop and speed regulation loop parameters of the variable speed drive that controls the motor for lifting the car. Specifically, the correct setting of these adjustment loops directly affects, on the one hand, the overall performance of the elevator and, on the other hand, directly the comfort and safety sensations felt by the elevator user. Effect. However, this setting is sometimes time consuming and / or complex to apply when a variable speed drive is activated.

  Patent document 1 already describes a method that allows automatic operation of a variable speed drive in lifting applications. However, this method includes a pre-calibration phase prior to starting, during which it is clearly necessary to inject current into the motor while keeping the rotor stationary.

  Patent Document 2 discloses an apparatus that enables an elevator speed adjustment loop to be adjusted. Nevertheless, this device requires the use of a load sensor that allows the actual weight of the elevator car to be determined in order to automatically adjust the proportional gain of the speed regulation loop.

US Pat. No. 5,929,400 Japanese Patent Laid-Open No. 08-012206

  Accordingly, it is an object of the present invention to more easily and more easily operate a variable speed drive that controls a lifting motor by proposing an estimate of the proportional and integral gains of the speed regulation loop. These gains are calculated based on only a few user parameters to be input, without requiring a current injection step, so that the speed regulation loop can be easily preset. This setting is done off-line, ie the gain is calculated only once based on the parameters entered, and no further adjustment of the gain according to the actual weight of the load is required during the operation of the elevator. Be beneficial. Therefore, this method is simple and economical because it does not require a load sensor.

  Also, the parameters to be entered are beneficial, corresponding to the known physical size of the application. Since these parameters are easy to identify, these physical dimensions can therefore be entered very easily by the user. Therefore, according to the present invention, it is possible to reduce the time and cost of using a variable speed drive in, for example, an elevator type lifting application.

  For this reason, the present invention describes a method for setting the speed regulation loop of a variable speed drive designed to control a motor connected to a lifting load. The method includes calculating proportional and integral gains of the speed regulation loop as a function of the nominal linear speed of the car, the nominal frequency of rotation of the motor, the number of motor pole pairs, and the total weight of the load. . Total weight is a predetermined parameter that is not measured by the sensor.

  According to one feature, the load includes an elevator car and the total weight of the load is proportional to the nominal capacity of the elevator car, the weight of the elevator car, or the weight of the elevator car counterweight. The method is therefore beneficial, taking into account not only the weight of the elevator car but also the total weight of the entire system.

  According to another feature, the method calculates the motor inertia as a function of the nominal torque of the motor and the number of motor pole pairs, and refines the calculation of the proportional and integral gains of the speed regulation loop. Including.

  According to another feature, the method calculates a time constant that filters the speed measurement according to an information item representing the resolution of the encoder for measuring the nominal torque of the motor and the motor speed, and It also includes a step of refining the calculation of the proportional gain and integral gain.

  The present invention also provides a variable speed drive comprising a control system forming a speed regulation loop and designed to control a motor connected to a lifting load, the variable speed drive control system having such a setting. The invention relates to a variable speed drive with a calculation block using the method.

  Other features and advantages will be apparent in the following detailed description relating to embodiments given by way of example and represented by the accompanying drawings in which:

1 represents a partial view of a system for controlling a variable speed drive that controls a motor. It shows a simplified block diagram of the present invention the calculation of the proportional gain K _p and the integral gain K _I of the speed regulation loop.

  Referring to FIG. 1, the variable speed drive includes a control system for controlling the electric motor M. The motor M is a synchronous or asynchronous motor designed to drive lifting type loads, such as elevator type applications. In this type of application, the load (not shown) mainly comprises an elevator car, its counterweight, and associated cables.

The system for controlling the variable speed drive comprises a speed regulator 5 forming a speed regulation loop. In a known manner, the speed regulator 5 receives as input a setpoint resulting from the difference between the speed reference V _ref for the rotation of the motor M and the speed measurement V _mes for the rotation of the motor M. Speed regulator 5, using a proportional gain K _p and the integral gain K _I to form a speed adjustment loop. The output of the speed regulator 5 provides a reference Iq _ref for the motor torque current. The speed measurement value V _mes is supplied, for example, by the measurement module 9.

The control system for the variable speed drive also forms a current regulation loop. For this reason, the control system includes an adjuster 6 for adjusting the current of the torque I _q and a current adjuster 7 of the magnetic flux I _d . The torque current regulator 6 receives as input a set point resulting from the difference between the torque current reference Iq _ref and the measured torque current value Iq _mes . Thereafter, the outputs from the current regulators 6 and 7 are converted by the conversion module 8 into variable currents that are sent to each phase of the motor M.

FIG. 2 shows a block diagram illustrating various computational blocks of a system for controlling a variable speed drive that allows the proportional gain K _p and integral gain K _I of the speed regulation loop to be estimated in accordance with the present invention. . These gains K _p and K _I are used by the speed regulator 5 to form a speed regulation loop.

The function of the first calculation block 10 is to determine the total weight M _{tot of the} load to be moved. The function of the second calculation block 20 is to determine the _load inertia J _load by using the total weight M _tot calculated in the first block 10. The function of the third calculation block 30 is to determine K _p and K _I by using the _load inertia J _load calculated in the second block 20.

Optionally, the third calculation block 30 may use the value of the motor inertia J _mot calculated by the fourth calculation block 40. Similarly, the third calculation block 30 may use the bandwidth coefficient value calculated by the fifth calculation block 50 (see detailed description below).

In the case of an elevator, the load inertia J _load takes into account the inertia of the elevator car when the nominal capacity of the elevator is applied to the elevator car and the inertia of the counterweight of the car, excluding the inertia of the motor. The inertia of the elevator cable can be ignored. Load inertia J _load is the following parameters: M _tot = total weight of load being moved, F _nom = nominal frequency of motor rotation, P _N = number of motor pole pairs, V _nom = cage of the car Based on the nominal linear velocity, it is calculated by the following formula:
J _load = M _tot × (V _nom × P _N / (2π × F _nom )) ²

The nominal frequency of rotation of the motor F _nom represents the nominal frequency of rotation of the rotor of the motor. In the case of a synchronous motor, the nominal frequency F _nom of motor rotation corresponds to the frequency of the stator power supply. In the case of an asynchronous motor, the nominal frequency F _nom of rotation of the motor corresponds to the product of the frequency of the stator power supply and a slip factor of less than one. This slip factor can be considered fixed at the nominal point of motion.

According to a first simple embodiment, the lift motor inertia J _mot is selected to be a predetermined fixed value in the variable speed drive without user intervention. In that case, the total inertia J _{tot of the} application is determined as follows.
J _tot = J _mot + J _load = J _mot + M _tot × (V _nom × P _N / (2π × F _nom )) ²

Thereafter, the third block 30 calculates the proportional gain K _p and the integral gain K _I of the speed regulation loop. Therefore, the third block 30 uses the following formula.
K _p = α × ξ × J _tot / P _N
K _I = α ² × J _tot / P _N

In this case, α corresponds to the bandwidth coefficient of the speed adjustment loop (sometimes referred to as ω _BP ) and ξ corresponds to the attenuation coefficient (also referred to as stability coefficient) of the speed adjustment loop. In the first embodiment, the values of the coefficients α and ξ are determined in advance by being fixed to the values of α ₀ and ξ _{0 in} the variable speed drive.

Thus, the method for setting the speed regulation loop includes calculating gains K _p , K _I. K _p , K _I are the following user parameters: load nominal linear velocity V _nom , motor rotation nominal frequency F _nom , number of motor pole pairs P _N , and total weight of load being moved It is useful to calculate only according to M _tot . The parameters F _nom , P _N , and V _nom correspond to physical dimensions that are easily ascertained by the user in a given application, while the total weight M _tot may be more difficult for the user to ascertain. . The present invention therefore also proposes a simple estimation of the total weight M _tot .

The total weight M _{tot of the} load to be transferred is ignoring the weight of the cable, the weight of the empty car M _cab , the weight of the counterweight of the car M _ctp, and the weight M _load corresponding to the nominal capacity of the elevator car Is equal to the sum of
M _tot = M _cab + M _ctp + M _load

The total weight M _tot is preferably proportional to the nominal capacity M _load of the elevator car corresponding to the physical size that is easily ascertained by the user for a given elevator. Thus, by entering only this nominal capacity of the car, the first block 10 can estimate the total weight M _{tot of the} load. Without discrimination, this nominal capacity of the car M _load is entered by the user based on the maximum number of people (eg 8 people) or directly on the equivalent weight (eg 600 kg taking an average of 75 kg per person) Can be done.

Similarly, the total weight M _tot is proportional to the weight of the empty elevator car M _cab or the weight M _ctp of the elevator car counterweight. These two parameters also correspond to physical dimensions that are easily ascertained by the user in a given application. The calculation rules used are as follows:
The elevator is considered to be balanced, so the weight of the counterweight M _ctp is approximately equal to the sum of the empty car weight M _cab and 1/2 of the car's nominal capacity M _load .
The weight of the empty car M _cab is approximately equal to the nominal capacity M _{load of the} car.
-The weight of the elevator cable is negligible.

This gives:
M _{tot ≈3.5} × M _load , or M _{tot ≈3.5} × M _cab , or M _{tot ≈2.33} × M _ctp

Therefore, the total weight M _tot is proportional to each of the three physical sizes, so that it can be estimated quickly. The user has the option of entering only one of these physical magnitudes in the first calculation block 10 and calculating an estimate of the total weight M _tot of the moved load.

Of course, other similar rules can be used to estimate the total weight M _tot . Also, if the user can ascertain each of the three physical dimensions, namely the empty car weight M _cab , the counterweight weight M _ctp , and the car's nominal capacity M _load , of course, these The total weight M _tot can be calculated more accurately in the first block 10. In any case, the total weight M _tot is fixed and predetermined which need not be measured in real time by a sensor that gives the actual weight of the car during elevator operation, for example to take into account the number of people in the car. It turns out that it is a parameter.

According to the second embodiment, the inertia J _{mot of the} lift motor is fixed and not predetermined, so that it is a function of the number P _N of motor pole pairs and the nominal torque T _N of the motor. 4 calculation blocks 40 can be calculated. Thus, to calculate the lift motor's inertia J _mot , the user can add a further parameter, namely a motor parameter that is easy to input because it also corresponds to the known physical size of the motor. The nominal torque _TN must be entered. With this second embodiment, the value of the total inertia J _tot of the application can be improved and thus the calculation of the gains K _p and K _I can be refined. In the fourth block 40, the motor inertia J _mot is
J _mot = J ₀ × (T _N / T ₀ ) ^1.5 × P _N / 2
To be equal to
In this case, T ₀ represents a constant basic torque equal to 1 N · m, and J ₀ represents a fixed coefficient of inertia selected to be approximately equal to 10 ⁻⁵ kg · m ^2. ing.

The third embodiment makes it possible to further refine the calculation of the gains K _p , K _I. Therefore, the setting method calculates the value α _cal of the bandwidth coefficient α instead of taking a predetermined fixed value α ₀ . For this purpose, the fifth calculation block 50 calculates a time constant _T.sub.filt for the speed measurement filtering performed by the measurement module 9. FIG. The time constant _{T filt} is between the minimum value _{T filtmin} and maximum value _{T filtmax.}

The minimum value T _filtmin, when the rotational speed of the motor is measured, based nominal torque T _N of the motor and to the resolution N _S of encoder used for measuring the rotational speed V _mes of the motor determined Is done. This value _Tfiltmin is selected, for example, so that a maximum noise of 2% is added to the nominal torque _TN . The maximum value _Tfiltmax is also given by the stability limit of the system for controlling the variable speed drive.

In order to perform optimal _{settings, T filt} equals _{T filtmin,} it is necessary _{that T Filtmax} is to remain above _{T filtmin.} Based on these conditions, the calculated value α _cal of the bandwidth coefficient α is α _cal = ((N _S × T _N ) / (1000 × π × J _tot )) ^1/2
Is equal to

Further, the value α _cal can be grouped between two predetermined minimum extreme values and maximum extreme values.

Therefore, in order to calculate the value α _cal of the bandwidth coefficient α, the user is able to enter a further parameter, ie a parameter that is easy to input because it also corresponds to the known physical size of the application. You must enter a certain encoder resolution N _S.

Thus, the present invention is, by using a predetermined known functional parameters without the need for measuring sensor, determining a proportional gain K _p and the integral gain K _I of the speed regulation loop. Therefore, this method is very simple because it is only necessary to calculate the gains K _p , K _I once offline, ie before the actual operation of the elevator, and there is no need to recalculate or readjust the gains in real time. Easy to be.

Claims (7)

A setting method for setting a speed adjustment loop of a variable speed drive designed to control a motor (M) connected to a lifting load,
The nominal linear velocity of the load (V _nom ), the nominal frequency of rotation of the motor (F _nom ), the number of motor pole pairs (P _N ), and the total weight of the load (M _tot ), and calculating a proportional gain (K _p ) and an integral gain (K _I ) of the speed adjustment loop. 2. The setting method according to claim 1, wherein the load includes an elevator car, and the total weight of the load (M _tot ) is proportional to the nominal capacity of the elevator car. The setting method according to claim 1, wherein the load includes an elevator car, and the total weight (M _tot ) of the load is proportional to the weight of the elevator car. 2. The setting method according to claim 1, wherein the load includes an elevator car, and the total weight (M _tot ) of the load is proportional to the weight of the counterweight of the elevator car. The motor inertia (J _mot ) is calculated according to the motor nominal torque (T _N ) and the number of motor pole pairs (P _N ), and the proportional gain (K _p ) and integral gain (K _p ) of the speed adjustment loop are calculated. The setting method according to claim 1, further comprising a step of refining the calculation of _I ). The speed adjustment loop bandwidth coefficient is calculated according to the nominal torque of the motor (T _N ) and the resolution of the encoder for measuring the motor speed (N _S ), and the proportional gain (K _p ) of the speed adjustment loop and The setting method according to claim 1, further comprising a step of refining the calculation of the integral gain (K _I ). A variable speed drive with a control system forming a speed regulation loop and designed to control a motor connected to a lifting load,
The control system of the variable speed drive comprises a calculation block (10, 20, 30, 40, 50) using the method for setting the speed regulation loop according to any one of claims 1-6. Variable speed drive featuring

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