JP2000184800A - Vector controller of induction motor for elevator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vector controller which can prevent degradation of ride comfort because of low followability of torque with a vector controller using maximal efficient control. SOLUTION: Switching is performed between the following cases: where a torque current command iq* and an exciting current command id* are obtained by a flux/current command computing part 13 from a torque command sent from a speed control computing part 12, and where maximal efficiency operation is obtained by changing a ratio of the exciting current command to the torque current command according to a load by a maximal efficiency control part 18. A control switching command generator 19, when a speed command from a position controller 11 is within a control switching speed setting value with a small load change, switches it to the exciting current command and the torque current command from the maximal efficiency control part, and in any other case than the above, switches it to the exciting current command and the torque current command from the flux/current command computing part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vector control apparatus for an induction motor for an elevator, and more particularly to a current control for improving efficiency.

[0002]

2. Description of the Related Art When an induction motor is used as a drive source of an elevator, a vector control system is generally employed for the induction motor in order to satisfy the requirements of landing accuracy and riding comfort of the elevator car.

FIG. 5 is a block diagram of a vector control device for an induction motor for an elevator. Inverter 2 to drive the induction motor 1 is controlled current source is a voltage-controlled by PWM exciting current command i _d * and the torque current command i _q * voltage control signal by a digital calculation result of the current control unit 3 for v _u , V _v , v _w .

[0004] The current control system for the current control section 3 and the central portion is obtained even if the signal current i _v currents i _u two-phase induction motor 1 is in the feedback signal, the subtraction unit 4 from the detection signal of the i _w These three-phase current signals are converted into d- and q-axis two-phase currents by a three-phase / two-phase converter 5, and further converted into coordinate converters 6.
Rotational phase θ in the combined current detection signal i _d of the induction motor 1, a fixed / rotating coordinate conversion to i _q performed by.

The operation result of the current control unit 3 becomes two-axis voltage commands v _d and v _q of _d and _q . These voltage commands are subjected to rotation / fixed coordinate conversion by the coordinate conversion unit 7 in accordance with the phase θ. Are further converted into three-phase voltage control signals v _u , v _v , v _w by a two-phase / three-phase converter 8.

[0006] The speed control system of the induction motor 1 has a speed detection unit including a pulse pickup 9 and a speed detection circuit 10 to perform feedback control. The position controller 11 responds to not only the acceleration command according to the elevator car floor or the landing floor, but also the speed command in a pattern consisting of a constant speed and a deceleration area, as well as the acceleration command at the start of elevating and the number of occupants (weight measurement). Generates a load command. Speed control unit 12 obtains a digital calculating the speed setting value from the speed command and the acceleration command and the load command from the position controller 11, proportional integral (PI) calculation for the deviation of the speed setting value and the speed detection signal omega _r The result is obtained as a torque command T *.

The magnetic flux / current command calculator 13 separates the torque command T * into a secondary magnetic flux command λ * and a torque current command _iq *, and the torque current command _iq * is directly sent to the current controller 3. and then, the correction by the speed detection signal ω _r in the secondary flux command λ *. The exciting current calculation unit 14 outputs the secondary magnetic flux command λ *
, An excitation current command _id * is obtained as a command to the current control unit 3.

[0008] Slip angular frequency arithmetic unit 15, flux lambda (or excitation current command i _d *) and the torque current command iq * and the slip angular frequency from the secondary time constant tau ₂ of the motor ω determined by the excitation current calculation unit 14 _Ask for _s . The adder 16 obtains the primary angular frequency omega by adding the slip angular frequency omega _s and the speed detection signal omega _r. The integrator 17 calculates the rotational phase θ by integrating the primary angular frequency ω.

[0009]

In the conventional vector control apparatus, in order to prevent torque fluctuation in a transient state, the magnetic flux / current command calculation unit 13 excludes a constant output operation region except for a constant output operation region.
The secondary magnetic flux command λ * (excitation current command _id *) is always kept constant regardless of the operation state. For this reason, even when the load is light (in an elevator, the vehicle is operating at a constant speed with the weight of the car and the weight of the counterweight balanced), the same exciting current flows as when the load is heavy, and the light load is reduced. At times, the ratio of iron loss increases, and the electric-mechanical conversion efficiency of the motor decreases.

In order to solve this problem, in a vector control device for an induction motor for an electric vehicle, there has been proposed a method of maximizing the efficiency by changing an exciting current according to a load. This method focuses on the current ratio between the exciting component current and the torque component current from the motor equivalent circuit at the time of vector control taking into account iron loss, and derives a simple conditional expression that maximizes the efficiency for any load. The maximum efficiency control is obtained based on this conditional expression. The maximum efficiency control method will be described below in principle.

FIG. 6 shows an equivalent circuit when the induction motor is controlled by the vector. Each part constant here is
It becomes constant in a normal T-type equivalent circuit, L ₁ the primary self-inductance, L ₂ a secondary self-inductance, equivalent iron loss resistance R _m, mutual inductance, primary resistance R ₁ to M,
Assuming that R ₂ is a secondary resistance, the following equation is obtained.

[0012]

Lσ = (L ₁ L ₂ −M ² ) / L ₂ RC = α {(ωM) ² / R _m } (1) R ₂ ′ = α ² R ₂ M ′ = αM α = M / L ₂ omega: in power supply angular frequency above the equivalent circuit, the exciting component current i _d, as torque current i _q, Doing vector control in consideration of iron loss,
The primary current I ₁ and the slip angle frequency ω _S are given by the following equations.

[0013]

(Equation 2)

Here, _ic is the iron loss current, and is given by the following equation.

[0015]

Equation 3] _{i c = ωM'i d / R c} = R m i d / (ωM) ... (4) In addition, the torque T, when the pole pairs p, becomes the following equation.

[0016]

Equation 4] _{T = 3pM'i d i q ... (} 5) exciting current i _d takes into account the constant output range, a constant value i _dmax in the base speed omega ₀ or less, the terminal of the motor at higher speed Field weakening control is performed by the following equation so that the voltage becomes substantially constant.

[0017]

Equation 5] _{i d = i dmax × ω 0} / ω r ... (6) ω r: rotor speed also for total loss W _total of the induction motor, equivalent circuits above and (2) of FIG. 6 expression and From the expression (4), it is expressed by the following expression (7). However, it is assumed that R _m ² ≪ (ωM) ² .

[0018]

[6] ^{_{W total = 3R 1 I 1 2}} + 3R 2 'i q 2 + 3R C i c 2 + W m = 3 _{[(R 1 + R 2')} i q 2 + (R 1 + R m ') i d 2 +2 _{{R m / (ωM)}} R 1 i d i q ] _{+ W m ... (7) W} m: mechanical loss R _m '= [alpha] R _m Incidentally, the equivalent iron loss resistance R _m will vary by power frequency,
Assuming that the power loss frequency is proportional to the 1.6th power and the iron loss resistance R _m0 at the rated frequency f ₀ , the following relationship is obtained.

[0019]

R _m = R _m0 × (f / f ₀ ) ^{1 · 6} (8) Further, it is assumed that the mechanical loss is proportional to the square of the rotor angular velocity as in the following equation.

[0020]

W _m = K _m × ω _r ² (9) From these relationships and the equivalent circuit of FIG. 6, the loss of the motor can be obtained for an arbitrary speed and load torque.

On the other hand, the shaft output P _out of the motor is given by the following equation.

[0022]

P _out = ω _r × T−W _m (10) Accordingly, the efficiency η (%) of the motor is given by the following equation.

[0023]

Η = 100 × P _out / (P _out + W _total ) (11) Here, assuming that the ratio between the torque component current and the excitation component current is A,

[0024]

A = ( _iq / _id ) (12) From the torque of the above equation (5), the following equation is obtained.

[0025]

Equation 12] _{i d i q = T / 3pM} '... (13) i q 2 = (T / 3pM') A ... (14) i d 2 = T / (3pM'A) ... (15) wherein these Substituting into equation (7), the motor loss W
_total can be expressed as a function of the ratio A.

[0026]

W _total = (R ₁ + R ₂ ') (T / 3 pM') A + (R ₁ + R _m ') T / (3 pM'A) +2 ｛R _m / (ωM)｝ R ₁ T / ( pM ′) + W _m (16) Here, in order to maximize the efficiency of the electric motor in an arbitrary load state, it is sufficient to minimize the loss in the operating state. Therefore, assuming that ∂W _total / ∂A = 0, A
By solving for (= _iq / _id ), a condition that maximizes the efficiency can be obtained, and is expressed by the following equation.

[0027]

[Equation 14]

However, in the derivation of the above equation (17), strictly speaking, ω and R _m also become functions of A and are affected by the differentiation. However, when the rotation speed is fixed, these values are almost constant. Value.

Therefore, the torque current _iq and the exciting current _id
The ratio A can be determined by the above equation (17) of, for a given torque command T, becomes maximum efficiency current command value i _q, i _d
Is obtained by the following equation.

[0030]

(Equation 15)

FIG. 7 is a block diagram of an elevator vector control device for performing maximum efficiency control. In FIG. 7, a portion different from FIG. 5 is a maximum efficiency control portion 18 instead of the magnetic flux / current command calculation portion 13. The maximum efficiency control unit 18 provides the torque command T * with the above (18), (1)
9) For the performs computation (exciting current i _d seek flux λ Alternatively) that is, always perform vector control in the maximum efficiency.

In FIG. 7, the exciting current calculator 1 shown in FIG.
4 is provided with a high-speed magnetic flux control section 14A. The control section 14A improves the response delay of the torque with respect to the change in the exciting current.

That is, the response of the secondary magnetic flux to the change of the exciting current is delayed, and as a result, the response of the torque is delayed.
In order to improve the response delay of the secondary magnetic flux, the high-speed magnetic flux controller 14A pseudo-differentiates the magnetic flux command λ * to obtain an excitation current command _id *.

For example, the high-speed magnetic flux control unit 14A is configured as an operation block shown in FIG. In the figure, the relationship between the magnetic flux command λ * and the magnetic flux estimation value λe is as follows.

[0035]

(Equation 16)

By appropriately selecting the value of the proportional gain G in this equation, the time constant of the secondary magnetic flux response can be set to 1 / (1 + G) of the secondary time constant τ ₂ , thereby improving the torque response. Is done.

As described above, the conventional device attempts to improve the torque tracking delay by providing the high-speed magnetic flux controller 14A in the maximum efficiency controller 18, but cannot reduce the torque tracking delay to zero. The occurrence of the delay in following the torque may deteriorate ride comfort when the maximum efficiency control is employed in the vector control device for the elevator.

[0038] It is an object of the present invention to provide a vector control device that employs maximum efficiency control and prevents a deterioration in ride quality due to a delay in following a torque.

[0039]

The present invention focuses on the fact that the delay in following the torque in the vector control is a problem when the load of the motor is rapidly and largely changed, and is not a problem in other cases. In a state where load fluctuation is relatively small, such as a constant speed operation state of an elevator, the normal vector control is switched to the maximum efficiency control.
A state in which the load fluctuation is small can be determined as a case where the speed command or the detected speed value is at a high speed in the constant speed operation region past the acceleration or deceleration region, or as a case where the acceleration command is close to zero.

Also, according to the present invention, the ride comfort of the elevator becomes a problem when there is an occupant in the elevator car. Therefore, when no person is on the elevator car, the acceleration, constant speed, The maximum efficiency control is performed in the entire deceleration operation range, and further combined with the above-described control switching based on the load state. The state where there is no occupant in the elevator car can be determined from a load command or the like from the position controller.

As described above, the present invention has the following features.

(First Invention) An induction motor is used as a drive source of an elevator, and a torque current command and an excitation current command are obtained by a magnetic flux / current command calculating means from a torque command obtained in a speed control system, and the induction motor is vector-controlled. A vector control device for an induction motor for an elevator, wherein a maximum efficiency control means capable of obtaining a maximum efficiency operation by changing a ratio of the excitation current command and the torque current command obtained from the torque command according to a load; and When the speed command of the control system is in a range where the load variation is small, the excitation current command and the torque current command are switched from the maximum efficiency control means. And a control switching command generating means for switching to a torque current command.

(Second invention) The control switching command generating means switches between an exciting current command and a torque current command from the maximum efficiency control means when the speed detection signal of the induction motor is in a range where the load variation is small. When the value is out of the range, the magnetic flux / current command calculation means switches between the excitation current command and the torque current command.

(Third invention) The control switching command generating means switches between an exciting current command and a torque current command from the maximum efficiency control means when an acceleration command of a speed control system is in a range close to zero. At other times, the switching between the excitation current command and the torque current command from the magnetic flux / current command calculation means is performed.

(Fourth Invention) The control switching command generation means switches between the excitation current command and the torque current command from the maximum efficiency control means when there is no occupant in the elevator car, and the occupant is in the elevator car. It is characterized in that at the time, switching is made between an excitation current command and a torque current command from the magnetic flux / current command calculation means.

[0046]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 is a block diagram of a vector control device showing an embodiment of the present invention. 7 is different from FIG. 7 in that the magnetic flux / current command calculation unit 13 in FIG. 5 is provided in parallel with the maximum efficiency control unit 18 and the excitation current calculation unit 14 is provided in parallel with the high-speed magnetic flux calculation unit 14A. These outputs are switched by the control switching command generator 19.

The control switching command generator 19 is provided with the position controller 1
The magnitude of the speed command from No. 1 and the control switching speed set value are compared, and when the speed command is equal to or less than the set value, normal vector control by magnetic flux / current command calculation means combining the calculation unit 13 and the excitation current calculation unit 14 ( When the speed command exceeds the set value, the control is switched to the maximum efficiency control (the configuration of FIG. 7) by the maximum efficiency control means combining the control unit 18 and the high-speed magnetic flux control unit 14A. Note that the magnetic flux λ (or the excitation current command i) to be input to the slip angle frequency calculation unit 15
_d *) is also switched.

Here, the set value of the control switching command generator 19 is a value close to the speed in the constant speed operation state of the elevator, that is, the speed immediately before shifting from the acceleration operation to the constant speed operation, or the deceleration from the constant speed operation. Set a value that corresponds to the speed immediately before shifting to operation.

According to this embodiment, the maximum efficiency control is performed only when the load fluctuation is small such as when the elevator is operating at a constant speed, and the normal vector control is performed when the load fluctuation is large such as during other acceleration / deceleration operations. In addition, it is possible to prevent the ride comfort from deteriorating while increasing the driving efficiency.

(Second Embodiment) In the first embodiment, since the constant speed operation state of the elevator is determined by the speed command from the position controller 11, the actual speed follows the speed command for some reason. Is delayed, the vehicle is operated under the maximum efficiency control even when the load fluctuates greatly.

[0051] Therefore, in this embodiment, as showing a main configuration diagram in FIG. 2, compared with the control switching speed set value and control switching command generator 19 in the speed detection signal omega _r, the speed detection signal omega _r Is less than or equal to the set value, normal vector control is performed by a combination of the calculation unit 13 and the excitation current calculation unit 14,
When the speed detection signal exceeds the set value, the control is switched to the maximum efficiency control by the combination of the control unit 18 and the high-speed magnetic flux control unit 14A.

According to the present embodiment, in addition to the operation and effect of the first embodiment, it is possible to reliably prevent switching to the maximum efficiency control in a state where the load fluctuates greatly.

(Third Embodiment) In the elevator vector control device, the position controller 1 is used to improve the riding comfort.
1 generates an acceleration command in addition to a speed command. When the acceleration command is zero, the load torque does not fluctuate because the elevator is not accelerated or decelerated.

In this embodiment, as shown in FIG. 3, the control switching command generator 19 determines whether or not the acceleration command is close to zero. Is the maximum efficiency control by the combination of the control unit 18 and the high-speed magnetic flux control unit 14A.
The control is switched to the normal vector control by the combination of No. 3 and the exciting current calculation unit 14.

Also in the present embodiment, it is possible to improve the efficiency while preventing the ride comfort from deteriorating.

The present embodiment is different from the first or second embodiment described above.
It is also possible to switch between maximum efficiency control and normal vector control in combination with the embodiment.

(Fourth Embodiment) In the elevator vector control device, when no person is in the car, the ride comfort is maintained even when the vehicle is operated under the maximum efficiency control in all the acceleration, constant speed, and deceleration operation regions. Become irrelevant.

Therefore, in this embodiment, when the information that no person is on the elevator car is obtained, the operation is performed with the maximum efficiency control in the entire operation range.

The position controller 11 generates a load command so as to change the torque command depending on whether or not a person is on the elevator car. In the present embodiment, as shown in the main part configuration diagram of FIG.
The load command from No. 1 is fetched, and when the load command does not include the occupant, the maximum efficiency control is performed. When the load command includes the occupant, the control is switched to the normal vector control.

The determination as to whether or not a person is riding in the elevator car is not limited to being obtained from the load command. For example, a sensor provided at the entrance of the elevator car may be used to detect the getting on and off of the person, It may be detected from the magnitude of the motor current at the time.

This embodiment can be combined with the above embodiments. For example, even when the load command is for an occupant, the control is switched to the maximum efficiency control when the speed command exceeds the control switching speed set value. With such a combination, it is possible to drive with maximum efficiency without deteriorating the riding comfort.

The switching between the maximum efficiency control and the normal vector control in each of the above embodiments is preferably performed gradually in order to avoid the occurrence of torque shock due to a rapid change in the value. For example, in order to switch the torque current command _iq * from the output of the calculation unit 13 to the output of the maximum efficiency control unit 18, a constant slope or a time constant is provided from the output of the calculation unit 13 to the output of the control unit 18. And gradually change it.

[0063]

As described above, according to the present invention, the normal vector control is switched to the maximum efficiency control when the load fluctuation is relatively small, and the elevator is controlled when no person is on the elevator car. Since the maximum efficiency control is performed in the entire operation range of, the efficient vector control can be performed without deteriorating the riding comfort of the elevator.

[Brief description of the drawings]

FIG. 1 is a block diagram of a vector control device according to a first embodiment of the present invention.

FIG. 2 is a main part block diagram showing a second embodiment of the present invention.

FIG. 3 is a main part block diagram showing a third embodiment of the present invention.

FIG. 4 is a main part block diagram showing a fourth embodiment of the present invention.

FIG. 5 is a block diagram of a conventional general elevator vector control device.

FIG. 6 is an equivalent circuit of an induction motor at the time of vector control.

FIG. 7 is a block diagram of a conventional elevator vector control device using maximum efficiency control.

FIG. 8 is a block diagram of a high-speed magnetic flux controller in FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Induction motor 2 ... Inverter 3 ... Current control unit 11 ... Position controller 12 ... Speed control unit 13 ... Magnetic flux / current command calculation unit 14 ... Excitation current calculation unit 18 ... Maximum efficiency control unit 19 ... Control switching command generator

Claims (4)

[Claims] 1. A drive source for an elevator is an induction motor,
A vector control device for an induction motor for an elevator that vector-controls the induction motor by obtaining a torque current command and an excitation current command by a magnetic flux / current command calculation unit from a torque command obtained in a speed control system, wherein the excitation current obtained from the torque command A maximum efficiency control means capable of obtaining a maximum efficiency operation by changing a ratio between the command and the torque current command in accordance with the load; and the maximum efficiency when the speed command of the speed control system is within a small load variation range. Control switching command generation means for switching between the excitation current command and the torque current command from the control means and switching between the excitation current command and the torque current command from the magnetic flux / current command calculation means when the value is out of the range. A vector control device for induction motors for elevators. 2. An elevator driving source is an induction motor,
A vector control device for an induction motor for an elevator that vector-controls the induction motor by obtaining a torque current command and an excitation current command by a magnetic flux / current command calculation unit from a torque command obtained in a speed control system, wherein the excitation current obtained from the torque command A maximum efficiency control means capable of obtaining a maximum efficiency operation by changing a ratio of a command to a torque current command according to a load; and the maximum efficiency control when the speed detection signal of the induction motor is within a small load variation range. Control switching command generation means for switching between an excitation current command and a torque current command from the means, and switching to an excitation current command and a torque current command from the magnetic flux / current command calculation means when the value is out of the range. A vector control device for an elevator induction motor. 3. An induction motor is used as a drive source of the elevator,
A vector control device for an induction motor for an elevator that vector-controls the induction motor by obtaining a torque current command and an excitation current command by a magnetic flux / current command calculation unit from a torque command obtained in a speed control system, wherein the excitation current obtained from the torque command A maximum efficiency control means capable of obtaining a maximum efficiency operation by changing a ratio between the command and the torque current command in accordance with the load; and the maximum efficiency control means when the acceleration command of the speed control system is in a range close to zero. And a control switching command generating means for switching between the exciting current command and the torque current command from the magnetic flux / current command calculating means when the value is out of the range. Vector control device for elevator induction motors. 4. An induction motor is used as a drive source of the elevator,
A vector control device for an induction motor for an elevator, which obtains a torque current command and an excitation current command from a torque command obtained in a speed control system by a magnetic flux / current command calculation means and vector-controls the induction motor, wherein the excitation current obtained from the torque command A maximum efficiency control means capable of obtaining a maximum efficiency operation by changing the ratio of the command and the torque current command according to the load; and an excitation current command from the maximum efficiency control means when there is no occupant in the elevator car. Switch to torque current command,
A vector control device for an induction motor for an elevator, comprising: control switching command generation means for switching between an excitation current command and a torque current command from the magnetic flux / current command calculation means when an occupant is in an elevator car. .