WO2010003740A2

WO2010003740A2 - Method for setting the speed loop of a speed variator

Info

Publication number: WO2010003740A2
Application number: PCT/EP2009/056835
Authority: WO
Inventors: Stéfan Capitaneanu; Duro Basic; François Malrait
Original assignee: Schneider Toshiba Inverter Europe Sas
Priority date: 2008-06-30
Filing date: 2009-06-03
Publication date: 2010-01-14
Also published as: WO2010003740A3; ES2550948T3; JP2011526233A; EP2303744B1; EP2303744A2; CN102076589A; FR2933249B1; FR2933249A1

Abstract

The invention relates to a method for setting a speed regulating loop of a speed variator intended to control a motor connected to a lifting load. The method involves a step of calculating a proportional gain (KP) and an integral gain (Ki) of the speed regulating loop, as a function of the nominal linear speed of the load, of the nominal rotational frequency of the motor, of the number of pairs of motor poles and of the total mass of the load.

Description

Method of adjusting the speed loop of a variable speed drive

The present invention relates to a method of adjusting a speed control loop of a variable speed drive, the variable speed drive controlling a synchronous or asynchronous electric motor for driving a hoist load, in particular a booth. elevator.

To drive an electric motor, a variable speed drive usually comprises a control system having a motor speed control loop and a current regulation loop sent on the various phases of the motor. In a hoisting application, especially in an elevator, it is particularly important to adjust the parameters of the current control and speed control loops of the speed controller controlling the hoist motor of the cab. Indeed, the correct setting of these control loops directly affects firstly the overall performance of the elevator and secondly the feelings of comfort and safety that are perceived by the elevator users. However, this adjustment is sometimes long and / or complicated to implement at the time of commissioning of the drive controller.

The document US5929400 already describes a method allowing automatic commissioning of a variable speed drive in a lifting application. However, this method includes a pre-start pre-calibration phase during which it is in particular necessary to inject current into the motor by keeping the rotor locked.

JP 08 012206 shows a device for adjusting the speed control loop of an elevator. This device nevertheless requires the use of a load sensor to determine the actual mass of the elevator car, so as to automatically adjust the proportional gain of the speed control loop.

The invention therefore aims to facilitate and simplify the commissioning of a variable speed drive driving a hoist motor, by providing an estimate of the proportional gain and the integral gain of the speed control loop. These gains are calculated based only on a small number of user parameters to be filled in, without requiring current injection steps, which makes it possible to simply have a preset of the speed regulation loop. Advantageously, this setting is done off-line, ie the gains are calculated only once from the parameters entered, and no longer requires adjustment of the gains according to the actual mass of the load during the operation of the elevator. The method is therefore simple and economical because it does not require a load sensor.

In addition, said parameters to be filled in correspond advantageously to known physical quantities of the application. As they are easily identifiable, these physical quantities can thus be very simply introduced by a user. The invention thus makes it possible to reduce the time and the cost of implementing a variable speed drive in a hoisting application, for example of the elevator type.

For this purpose the invention describes a method of adjusting a speed control loop of a variable speed drive which is intended to drive a motor connected to a lifting load. The method comprises a step of calculating a proportional gain and an integral gain of the speed regulation loop, as a function of the linear nominal speed of the car, the nominal frequency of rotation of the motor, the number of pairs motor poles and the total mass of the load. The total mass is a predetermined parameter not measured by a sensor.

According to one characteristic, the load comprises an elevator car and the total mass of the load is proportional to the nominal capacity of the elevator car, to the mass of the elevator car or to the mass of a counterweight of the elevator car. Advantageously, the method therefore takes into account not only the mass of the elevator car but the total mass of the entire system.

According to another characteristic, the method also comprises a step of calculating an inertia of the motor as a function of the nominal torque of the motor and the number of pairs of poles of the motor, in order to refine the calculation of the proportional gain and the integral gain of the loop. speed control.

According to another characteristic, the method also comprises a step of calculating a filtering time constant of the speed measurement as a function of the nominal torque of the motor and information representative of the resolution of a speed measurement encoder. of the motor, to refine the calculation of the proportional gain and the integral gain of the speed control loop.

The invention also relates to a speed variator comprising a control system performing a speed control loop and intended to drive a motor connected to a lifting load, the control system of the variable speed drive comprising calculation blocks which implement such a method of adjustment. Other features and advantages will appear in the detailed description which follows with reference to an embodiment given by way of example and represented by the appended drawings in which: FIG. 1 represents a partial view of a control system of a variable speed drive controlling a motor, Figure 2 shows a simplified block diagram according to the invention of the calculation of the proportional gain K _P and the integral gain Ki of the speed control loop.

With reference to FIG. 1, a variable speed drive comprises a control system for the purpose of driving an electric motor M. The motor M is a synchronous or asynchronous motor which is intended to drive a lifting load, for example an application. elevator type. In this type of application, the load (not shown in the figures) then mainly comprises an elevator car, its counterweight and associated cables.

The drive control system includes a speed controller 5 which performs a speed control loop. In known manner, the speed controller 5 receives as input a setpoint from a deviation between a reference speed V M engine rotational _ref and a velocity measurement V _my engine rotation M. The speed controller 5 uses a proportional gain K _P and an integral gain K i to effect the speed control loop. The output of the speed controller 5 provides a reference of the motor torque current lq _ref . The speed measurement V _mes is provided for example by a measurement module 9.

The drive control system also performs a common regulation loop. For this purpose, it comprises a current regulator 6 of torque Iq and a current regulator 7 of flow Id. The torque current regulator 6 receives as input a reference coming from a difference between the reference of the torque current lq _ref and a measurement of the torque current lq _mes - The outputs of the current regulators 6 and 7 are then transformed into variable currents sent on each phase of the motor M by a transformation module 8.

FIG. 2 presents a block diagram showing different calculation blocks of the speed controller control system, making it possible to estimate a proportional gain K _P and an integral gain K i of the speed regulation loop, according to the invention. These gains K _P and Ki are used by the cruise control 5 to perform the speed control loop.

A first calculation block 10 has the function of determining the total mass M _to t of the displaced load. A second calculation block 20 has the function of determining the inertia of the load J | _0a d using the total mass M _to t calculated in the first block 10. A third calculation block 30 has the function of determining K _P and Ki using the inertia of the load J | _0a d calculated in the second block 20.

Optionally, the third calculation block 30 can use a value of the motor inertia J _word calculated in a fourth calculation block 40. Similarly, the third calculation block 30 can use a value of bandwidth coefficient calculated in a fifth Calculation block 50 (see details below).

In the case of an elevator, the inertia of the load J | _0a d takes into account the inertia of the elevator car when it is loaded with a nominal capacity of the elevator as well as the inertia of the counterweight of the cabin, outside the inertia of the engine. The inertia of the lift cables is considered negligible. The inertia of the load J | _0a d is calculated from the following parameters: M _to t = total mass of the displaced load, F _nom = nominal motor rotation frequency, P _N = number of motor pole pairs, V _nom = nominal linear speed of the motor cabin, thanks to the following formula:

Jι _oad = MM ^* (V _name ^* P _N / (2π ^* F _name )) ²

The nominal motor rotation frequency F _nom represents the nominal rotor rotation frequency of the motor. In the case of a synchronous motor, the nominal rotation frequency of the motor F _name corresponds to the stator power supply frequency. In the case of an asynchronous motor, the rated rotational frequency of the motor F _nom corresponds to the power supply frequency of the stator multiplied by a slip coefficient which is less than 1. This sliding coefficient can be considered as fixed for the nominal operating point.

According to a first simple embodiment, the inertia of the hoisting motor J _mo t is chosen to be a fixed value which is predetermined in the variable speed drive without the intervention of a user. The total inertia of the application J _to t is then determined as follows:

Jtot ⁼ Jmot ⁺ Jloεid ⁼ Jmot ⁺ M _to t * (V _name * P _N / (2π * F _name )) The third block 30 then calculates the proportional gain K _P and the integral gain K i of the speed control loop. For this, the third block 30 uses the following formulas:

where oc coefficient corresponds to a bandwidth of the speed control loop (sometimes referred to or _BP) and ξ corresponds to an attenuation coefficient (also called coefficient of stability) of the speed control loop. In the first embodiment, the values of these coefficients oc and ξ are fixed and predetermined in the variable speed drive, at values of Oc ₀ and ξ _{0, respectively} .

The method of adjusting the speed regulation loop therefore comprises a step of calculating the gains K _P and K |. Advantageously, the K _P and K i are only calculated according to the following user parameters: linear nominal speed V load _name , nominal rotation frequency F motor _name , number of P _N pole pairs of the motor and total mass M _to t the displaced load. The parameters F _name! PN and V _name correspond to physical quantities that are readily known by a user for a given application, while the total mass M _to t can be difficult to know for a user. The invention thus also proposes a simple estimate of the total mass M _to t.

The total mass M _to t of the displaced load is equal to the sum of the mass of the empty _cab M _cab , the mass of the counterweight M _ctp of the cab and the mass M | _0a d corresponding to the rated capacity in the elevator cabin, neglecting the mass of the cables.

Mtot = M _c + M _cab tp + Mioad

Preferably, the total mass M _to t is proportional to the Mioad nominal capacity of the elevator car corresponding to a physical quantity which is readily known by a user for a given lift. Thus, by entering only this nominal capacity of the cabin, the first block 10 is able to make a total mass estimate of the load M _to t. Regardless, this rated capacity M | _0a d of the cabin can be entered by the user from a maximum number of people (for example 8 people) or directly from the equivalent weight (for example 600 Kg, taking an average of 75 Kg per person) .

Likewise, the total mass M _to t is proportional to the mass of the empty elevator cabin M _c or to the mass of the counterweight M _ctp of the elevator car. These two parameters also correspond to physical quantities easily known by a user for a given application. The calculation rules used are as follows:

it is considered that the elevator is balanced, so the mass of the counterweight M _ctp is approximately equal to the mass of the empty cabin M _cab increased by half the nominal capacity M | _0ad from the cabin,

the mass of the empty _cab M _cab is approximately equal to the nominal capacity M | _0ad from the cabin,

- The mass of elevator cables is negligible.

We then obtain:

Mt _o t ≈ 3.5 ^* M | _0ad or Mt _o t ≈ 3.5 ^* M _cab or M _tot ≈ 2.33 ^* M _ctp

The total mass M is proportional _to t for each of the three physical quantities, allowing to quickly make an estimate. The user has the choice to enter only one of these physical quantities, so that the first calculation block calculates an estimate of the total mass M _to t of the displaced load.

Other similar rules could obviously be used to estimate the total mass M _to t. Moreover, if the user is able to know each of the three physical variables: mass of the empty _cab M _cab , mass of the counterweight M _ctp and nominal capacity M | _0ad of the cabin, then these three sizes can obviously be individually filled to calculate more precisely the total mass Mtot in the first block 10. In all cases, we see that the total mass M _to t is a fixed and predetermined parameter, which does not need to be measured in real time by a sensor giving the actual mass of the cabin during operation of the elevator, to take into account for example the number of people in the cabin.

According to a second embodiment, the inertia of the lifting motor J _mo t is not fixed and predetermined, but can be calculated in the fourth block 40 of calculation, as a function of the number of pairs of poles of the motor P _N and the nominal torque of the motor T _N. To calculate an inertia of the hoisting motor J _mo t, the user must therefore enter an additional parameter, namely the nominal torque of the motor T _N which is an easy parameter to enter because it also corresponds to a known physical quantity of the engine. This second embodiment makes it possible to improve the value of the total inertia of the application J _to t and thus to refine the calculation of the gains K _P and K | In the fourth block 40, the inertia of the motor J _word is calculated as being equal to:

Jmot ⁼ Jθ * (T _N / TQ) '* P _N / 2 wherein T ₀ represents a constant base pair equal to 1 N. m and in which Jo represents a fixed coefficient of inertia which is chosen to be substantially equal to 10 ^-5 kg.m ² .

A third embodiment makes it possible to further refine the calculation of the gains K _P and K |. For this, the control method calculates a value of the bandwidth OCAI α band coefficient, instead of taking the predetermined fixed value Oc _0. For this, the fifth calculation block 50 calculates a time constant T _f , ι _t for the filtering of the speed measurement made by the measurement module 9. This time constant T ™ lies between a minimum value T _f | _tmιn and a maximum value T _fl ιt _ma χ.

The minimum value T _fl | _tmιn is determined from the nominal torque of the motor T _N and the resolution N _s of an encoder used to measure the speed of rotation V _mes of the motor, in the case where this speed of rotation is measured. This value T _fl | _tmιn is for example chosen to have a maximum noise of 2% compared to the nominal torque T _N. Moreover, the maximum value T _fl ιt _ma χ is imposed by the stability limits of the control system of the variator.

To have an optimal setting, one must make sure that T _fl | _t is equal to T _fl | _tmιn and that Tfπtmax remains greater than or equal to T _fl | _tmιn . These conditions cause a OCAI calculated value of the pass-band coefficient α which is equal to: αcai = ((N _s _N ^* T) / (1000 ^* π ^* Jtot)) ^{l / 2}

In addition, it is possible to frame the value Ocai between two predetermined minimum and maximum extreme values.

Thus, in order to calculate an ocai value of the bandwidth coefficient α, the user must therefore provide an additional parameter, namely the encoder resolution N _s, which is an easy parameter to be informed because it also corresponds to a physical quantity known to the user. application.

The invention thus determines the proportional gain K _P and the integral gain K i of the speed control loop by using predetermined and known functional parameters, without the need for a measurement sensor. The method is therefore very simple because the calculation of the gains K _P and Ki can be performed once "off-line", that is to say before the actual operation of the elevator, since the gains do not need to be recalculated or readjusted in real time.

Claims

1. A method for adjusting a speed control loop of a variable speed drive which is intended to drive a motor (M) connected to a lifting load, characterized in that the method comprises a step of calculating a speed proportional gain (K _P ) and integral gain (Ki) of the speed control loop, as a function of the nominal linear speed (V _n0m ) of the load, the nominal rotation frequency (F _name ) of the motor , the number of pairs of poles (P _N ) of the motor and the total mass (M _to t) of the load, the total mass (M _to t) being a predetermined parameter not measured by a sensor.

2. Adjustment method according to claim 1, characterized in that the load comprises an elevator car and the total mass (M _to t) of the load is proportional to the nominal capacity of the elevator car.

3. Adjustment method according to claim 1, characterized in that the load comprises an elevator car and the total mass (M _to t) of the load is proportional to the mass of the elevator car.

4. Adjustment method according to claim 1, characterized in that the load comprises an elevator car and the total mass (M _to t) of the load is proportional to the mass of a counterweight of the elevator car.

5. Adjustment method according to one of the preceding claims, characterized in that the method also comprises a step of calculating a motor inertia (J _word ) as a function of the nominal torque (T _N ) of the engine and the number of pairs of poles (P _N ) of the motor, to refine the calculation of the proportional gain (K _P ) and the integral gain (Ki) of the speed control loop.

6. Adjustment method according to one of the preceding claims, characterized in that the method also comprises a step of calculating a bandwidth coefficient of the speed control loop as a function of the nominal torque (T _N ) of the engine and the resolution (N _s ) of an encoder for measuring the speed of the motor, in order to refine the calculation of the proportional gain (K _P ) and the integral gain (Ki) of the speed control loop.

Speed variator comprising a control system performing a speed control loop and intended to drive a motor connected to a lifting load, characterized in that the control system of the variable speed drive comprises calculation blocks (10, 20, 30, 40, 50) which implement the control method of the speed control loop according to one of the preceding claims.