KR20110016758A

KR20110016758A - Motor speed estimator with a velocity sensor for motor driving system

Info

Publication number: KR20110016758A
Application number: KR1020090074415A
Authority: KR
Inventors: 홍찬욱
Original assignee: 엘에스산전 주식회사
Priority date: 2009-08-12
Filing date: 2009-08-12
Publication date: 2011-02-18

Abstract

PURPOSE: A motor speed estimator with a velocity sensor for a motor driving system is provided to improve motor speed controlling performance in low speed region by reflecting the average value of estimated speed in an estimation error operating process. CONSTITUTION: An estimation error operator(601) includes a first storage(701), a first subtractor(702), a first absolute value operator(703), a first comparator(704), a second storage(705), a second subtracter(706), a second absolute value operator(707), a second comparator(708), a counter(709), a third storage(710), a division operator(711), and a third subtracter. The first storage is in connection with the output terminal of a detection torque operator. Detection torque is periodically inputted into the first storage. The first subtracter is in connection with the output terminal of the first storage. The first absolute value operation is in connection with the output terminal of the first substrator.

Description

Speed estimation device for motor drive system with speed sensor {MOTOR SPEED ESTIMATOR WITH A VELOCITY SENSOR FOR MOTOR DRIVING SYSTEM}

The present invention relates to a motor drive system having a speed sensor, and more particularly, to a speed estimating apparatus for the motor drive system.

When the variable speed drive of an AC motor by an inverter is widely used, when a precise speed control is required, a method of detecting and controlling the motor speed by attaching a speed detection sensor to the motor is widely used. Incremental encoders are commonly used as speed detection sensors, and resolvers are used in places where environmental performance is required, such as automobiles.

The encoder outputs two-phase pulses having a phase difference of 90 degrees from each other by a predetermined number per rotation, and the speed detection device of the inverter detects the speed of the electric motor by counting the pulses every predetermined time. In the case of a resolver, it is possible to obtain a two-phase pulse signal such as an encoder by connecting a resolver to digital (R / D) converter to the resolver output, so the principle of speed detection is the same.

In general, an optical encoder that is used frequently has more than 1,000 pulses per rotation, but a magnetic encoder having excellent environmental resistance but low resolution has several hundred to several tens of pulses per rotation.

In the case of using an encoder having a low resolution, that is, a low number of pulses per revolution, and in a low speed region, the interval between pulses becomes long, which increases the time delay of speed detection.

In order to prevent the deterioration of the speed detection performance in the low speed region caused by the long output pulse interval due to the sensor characteristic, an estimator (observer) can be added. A speed estimating apparatus with improved speed detection in the area is provided.

An object of the present invention is to provide a speed estimating apparatus having an improved estimation performance in a low speed region in which a motor speed is low when using a low resolution speed sensor in a speed estimating apparatus for a motor drive system having a speed sensor.

An object of the present invention is to provide a speed estimation apparatus for a motor drive system having a speed sensor,

The estimated speed of the motor is calculated based on the detected rotational speed of the motor obtained by calculating the number of pulses output by the speed sensor and the speed detection period, and the torque-minute current.

A motor having a speed sensor according to the present invention, characterized in that it comprises a; speed estimator having an estimation error calculating unit for calculating the estimation error based on the average value of the estimation speed so as to reduce the estimation error in the low-speed calculation It can be achieved by providing a speed estimating apparatus for the drive system.

In addition, an object of the present invention, in the speed estimation device for a motor drive system having a speed sensor,

A speed estimator having an estimation error calculating section for calculating the estimation error based on the average value of the estimation speeds so as to reduce the estimation error in the low speed calculation,

The estimated speed is,

here,

Is the estimated speed,

Is the integrator, J is the inertia of the motor,

Silver electric motor torque,

Is estimated load torque, k1 and k2 are gain,

Can be achieved by providing a speed estimating apparatus for an electric motor drive system having a speed sensor according to the present invention, characterized in that it is obtained by the above equation 1 which is the detected rotational speed.

The speed estimating apparatus for a motor drive system having a speed sensor according to the present invention can minimize the estimation error in the low speed calculation of the speed estimating apparatus by reflecting the average value of the estimated speed at the time of calculating the estimation error (calculation). Speed control performance can be improved.

The purpose and structure and effect of the present invention to achieve the above will be more clearly understood by the following detailed description of the preferred embodiment of the present invention with reference to the accompanying drawings.

First, a system configuration diagram showing an overall system configuration of an electric motor drive system including a speed estimating apparatus according to the present invention will be described with reference to FIG. 1.

In Fig. 1, reference numeral 501 denotes an inverter for controlling the motor drive which occupies the main part of the motor drive system. The inverter 501 outputs a voltage to the motor 502 which causes the motor 502 to which the incremental encoder 503 is attached as the speed (position) sensor to rotate to the value of the set speed command Wm *. The setting of the speed command Wm * is a speed command value set by the user through the setting operation unit (not shown) in the inverter 501.

The electric motor 502 may be, for example, a permanent magnet synchronous AC motor as an AC motor.

The incremental encoder 503 is a speed (position) sensor mounted on the rotation shaft of the motor 502 and outputs a pulse (pulse signal) proportional to the rotation when the rotation shaft of the motor 502 rotates. .

The pulse amplifier 514 is connected to the output terminal of the incremental encoder 503, and receives a pulse train (a plurality of pulses input in one detection period) which is an output of the incremental encoder 503, and thus the mechanical magnetic flux angle of the motor rotor. Calculate (Θ _m ).

The detection rotation speed calculator 516 receives the mechanical magnetic flux angle Θ _m , which is the output of the pulse amplifier 514, calculates the detection rotation speed W _mMT of the motor 502, and the corresponding detection rotation speed W _mMT is It is provided as one input of speed estimator 518 that is a feature of the present invention.

The speed estimator 518 receives the torque current (i _q ) and the detection rotation speed (W _mMT ) from the detection rotation speed calculator (516) and calculates the torque current (i _q ) and the detection rotation speed (W _mMT ). Based on the estimated speed of the motor 502

) Is calculated.

The subtractor 504 is connected to the output terminal of the speed estimator 518, and the set speed command W _m * and the estimated speed (

Find the difference between and detect the speed error.

The speed control device 505 is connected to the output terminal of the subtractor 504, converts the speed error from the subtractor 504 into a torque-minute current command value i _q ^* , and outputs it. Here, the torque minute current command value i _q ^* is obtained by multiplying the speed error by (Kp_s + Ki_s / s), where Kp_s is proportional gain, Ki_s is integral gain, and s is the Laplace operator.

The subtractor 506 is connected to the output terminal of the speed control device 505, the determined difference between the torque current command (i _q ^*) and a torque current (i _q) from the speed control unit 505, torque current error Detect.

The torque current control device 508 is connected to the output terminal of the subtractor 506, and receives the torque minute current error provided from the subtractor 506 to calculate a corresponding torque minute voltage command value Vq ^* . Here, the torque-minute voltage command value Vq ^* is obtained by multiplying the torque-minute current error by (Kp_q + Ki_q / s), where Kp_q is proportional gain, Ki_q is integral gain and s is the Laplace operator.

The flux current command calculator 517 is connected to the output end of the speed estimator 518, the output end of the torque current control device 508, and the output end of the flux current control device 509, and the estimated speed (

) And the torque current control device torque minute voltage command value from the (508) (V _q ^*) and a magnetic flux received magnetic flux minute input to the voltage command (V _d *) from the current control device 509, the magnetic flux minute current command (i _d *) To calculate.

The subtractor 507 is the magnetic flux minute is connected to the output terminal of the current command calculator 517, the magnetic flux minutes, the current command calculator 517, the magnetic flux by subtracting the magnetic flux minute current (i _d) from the magnetic flux minute current command (i _d *) from The magnetic flux current error is detected by calculating the difference value between the minute current command i _d * and the magnetic flux current i _d .

The magnetic flux current control device 509 is connected to the output terminal of the subtractor 507 and receives the magnetic flux current difference provided from the subtractor 507 to calculate a corresponding magnetic flux minute voltage command value V _d ^* . Here, the magnetic flux split voltage command value V _d ^* is obtained by multiplying the magnetic flux split current error by (Kp_d + Ki_d / s), where Kp_d is proportional gain, Ki_d is integral gain, and s is the Laplace operator.

The current control device 510 is connected to the output terminals of the torque current control device 508 and the magnetic flux current control device 509, and the torque voltage command V _q * and the magnetic flux current which are outputs of the torque current control device 508. The three-phase voltage commands V _a *, V _b *, according to the electric magnetic flux angle Θ _e of the rotor in the motor 502, to which the magnetic flux voltage command V _d *, which is the output of the control device 509, is input. It is a two-phase to three-phase converter to convert to V _c *.

The voltage control device 511 is a power semiconductor element (for example, a thyristor, an IGBT (Insulated Gate Bipolar Transistor), etc.) that forms an arm of a switching element provided in pairs for each of three phases, and three phases. Control the on or off switching duty of the power semiconductor device through the pulse width modulaiton by receiving the voltage command (V _a *, V _b *, V _c *) And a pulse width modulator configured to apply a three-phase output voltage according to three-phase voltage commands Va _a , V _b and V _c * to an input terminal of the motor 502.

The phase current sensors 112a, 112b, 112c are connected to the three-phase output lines of the voltage control device 511, respectively, to detect three-phase currents i _a , i _b , i _c flowing through the electric motor 502. Preferably, the phase current sensors 112a, 112b, and 112c may be configured as current transformers.

The three-phase to two-phase converter 513 is connected to the output terminals of the phase current sensors 112a, 112b, and 112c, and the three-phase currents i _a , i _b , and i _c from the phase current sensors 112a, 112b, and 112c. ) Is converted into torque component current i _q and magnetic flux current i _d according to the electrical magnetic flux angle Θ _e of the rotor in the motor 502 and output.

The multiplier 515 is connected to the output of the pulse amplifier 514 and multiplies the mechanical flux angle Θ _m from the pulse amplifier 514 by a constant of K = 2 / number of poles to provide electrical Calculate the magnetic flux angle Θ _e .

Meanwhile, referring to FIG. 2, which is a functional block diagram showing only a detailed configuration of only the speed estimating apparatus according to the present invention, and with reference to FIG. 1, the detailed configuration and operation of the speed estimating apparatus that is a feature of the present invention will be described below. Is the same as

The speed estimating apparatus according to the present invention, which can refer to FIG. 2, is a speed estimating apparatus for a motor drive system having a speed sensor. In FIG. The detected rotational speed (W _mMT ) of the motor calculated by the pulse amplifier 514 and the detected rotational speed calculator 516 of FIG. 1 and the torque provided by the three-phase to two-phase converter 513 of FIG. The estimated speed of the motor 502 based on the (torque) minute current i _q

A speed estimator 518 that computes < RTI ID = 0.0 >

The speed estimator 518 may estimate the speed (e.g., reduce the estimated error in the low speed operation).

And an estimation error calculating unit that calculates the estimation error based on the average value of?

The detailed configuration and operation of the speed estimator 518 will be described with reference to FIG. 2.

The speed estimator 518 includes an estimation error calculator 601, a first multiplier 602, a first integrator 603, a second multiplier 604, a third multiplier 605, and a fourth multiplier. 606, and a calculator 607 and a second integrator 608.

The estimation error calculator 601 is connected to the output terminal of the detection rotation speed calculator 516 and the output terminal of the speed estimator 518 of FIG. 1, and receives the detection rotation speed W _mMT from the detection rotation speed calculator 516. From the output of the estimator 518, the estimated speed (

) Is inputted. The estimation error calculating unit 601 detects the detected rotation speed W _mMT and the estimated speed (

), The detection rotation speed (W _mMT ) and the estimated speed (

Estimation error with minimal difference

) And print it. A more detailed configuration and operation of the estimation error calculator 601 will be described later with reference to FIG. 3.

The first multiplier 602 is connected to the output terminal of the three-phase two-phase converter 513 of FIG. 1, and the motor torque constant K _t is applied to the torque component current i _q from the three-phase two-phase converter 513. Multiply by) to calculate the motor torque τ _m .

The first integrator 603 is connected to the output terminal of the estimation error calculating unit 601 to estimate the estimation error from the estimation error calculating unit 601 (

) Is multiplied by the first gain (k ₂ ) (also known as the observer gain) and then integrated to determine the load torque estimate (

) Is calculated.

The second multiplier 604 is connected to the output terminal of the first multiplier 602, and the inertia J of the motor (see 502 in Fig. 1) is connected to the motor torque τ _m output by the first multiplier 602. reciprocal(

Multiply by) to print.

The third multiplier 605 is connected to the output terminal of the first integrator 603, so that the load torque estimate (1) output by the first integrator 603 is output.

) Is the inverse of the inertia (J) of the motor (see 502 in FIG. 1)

Multiply by) to print.

The fourth multiplier 606 is connected to the output terminal of the estimation error calculating unit 601 to estimate the estimation error from the estimation error calculating unit 601 (

) Is multiplied by the second gain k ₁ and outputted.

The calculator 607 is a kind of adder connected to the output terminal of the second multiplier 604, the output terminal of the third multiplier 605, and the output terminal of the fourth multiplier 606, and outputs the motor torque (the output of the second multiplier 604). τ _m ) is the inverse of the inertia (J) of the motor (see 502 in FIG. 1)

) And the estimated error (4) output by the fourth multiplier 606

) Is added by multiplying the second gain (k ₁ ) by the load gain estimate (3) by the third multiplier (605).

) Is the inverse of the inertia (J) of the motor (see 502 in FIG. 1)

Subtract the value multiplied by) and print it out.

The second integrator 608 is connected to the output terminal of the calculator 607 and integrates the value output from the calculator 607 to estimate the speed (

) Is calculated.

Meanwhile, the detailed configuration and operation of the estimation error calculator will be described with reference to FIG. 3, which is a functional block diagram showing the detailed configuration of the estimation error calculator in FIG. 2.

The estimation error calculating unit 601 includes a first storage unit 701, a first subtractor 702, a first absolute value calculator 703, a first comparator 704, and a second storage unit 705. And a second subtractor 706, a second absolute value calculator 707, a second comparator 708, a counter 709, a third storage unit 710, a division calculator 711, And a third subtractor 712.

The first storage unit 701 is connected to the output terminal of the detection rotation speed calculator 516 as shown in FIG. 1, and _thus detects the rotation speed W _mMT of the electric motor 502 of FIG. 1 from the detection rotation speed calculator 516. ) Is periodically input and stored and output until a new detected rotation speed is entered.

The first subtractor 702 is connected to an output terminal of the detection rotation speed calculator 516 and an output terminal of the first storage unit 701 as shown in FIG. 1, so as to detect a current from the output terminal of the detection rotation speed calculator 516. The _{difference is} calculated by the first storage unit 701 subtracting the detection rotation speed W _mMT (of the previous detection period) before one detection period from the detection rotation speed W _{mMT in the} period.

The first absolute value calculator 703 is connected to the output terminal of the first subtractor 702 and outputs the absolute value of the value (calculated value of the difference) output by the first subtractor 702.

The first comparator 704 is connected to the output terminal of the first absolute value calculator 703, and outputs 1 if the value output by the first absolute value calculator 703 is greater than or equal to a predetermined value, and the first absolute value. If the value output from the calculator 703 is smaller than the predetermined value, 0 is output to detect a change in the detection rotation speed W _mMT . That is, if the first comparator 704 outputs 1, _there is a change (relative to the previous value) in the detection rotation speed W _mMT , and if the first comparator 704 outputs 0, the detection rotation speed W _mMT There is no change (relative to the previous value).

The second storage unit 705 is connected to the output terminal of the speed estimator 518, and the estimated speed (from the speed estimator 518).

) Is periodically input and stored and output until the next estimated speed is entered.

The second subtractor 706 is connected to the output terminal of the speed estimator 518 and the output terminal of the second storage unit 705, so that the estimated speed in the current detection period output by the speed estimator 518 (

) And the estimated speed before the detection period as long as the second storage unit 705 outputs (i.e., 1)

Computes the difference between In other words, the second subtractor 706 estimates the estimated speed in the current detection period output by the speed estimator 518.

As long as the second storage unit 705 outputs (i.e., 1) the estimated speed before the detection period (

) And subtract the output.

The second absolute value calculator 707 is connected to the output terminal of the second subtractor 706 and outputs the absolute value of the value (calculated value of the difference) output by the second subtractor 706.

The second comparator 708 is connected to the output terminal of the second absolute value calculator 707, and outputs 1 when the value output by the second absolute value calculator 707 is greater than or equal to a predetermined value, and the absolute value calculator If the value to be output is smaller than the predetermined value, 0 is output and the estimated speed (

) Detects a change. That is, when the second comparator 708 outputs 1, the estimated speed (

) Is compared to the previous value, and the second comparator 708 outputs 0, the estimated speed (

) Has no change (relative to previous value).

The counter 709 is connected to the output terminal of the second comparator 708 and the output terminal of the first comparator 704, and inputs an output value from the second comparator 708 so that the output value of the second comparator 708 is one. Increasing the counter value by 1, inputting the output value from the first comparator 704, and when the output value of the first comparator 704 is 1, outputs the counter value that has been increased to the present as a counter output and simultaneously internally. Reset the counter value to 1.

The third storage unit 710 is a mass storage device and is connected to an output terminal of the second comparator 708, an output terminal of the first comparator 704, and an output terminal of the speed estimator 518, and is output from the speed estimator 518. Estimated speed (

), And when the output from the first comparator 704 becomes 1, all estimated speeds

In addition to summing the values of ()) and at the same time clear the previously stored values, and stores the value of the estimated speed entered at the present time in the first storage location. In other words, the third storage unit 710 has a total of m estimated speeds (

), The third storage unit 710 has a unit memory device from address 1 to m. Estimated speed (

When the output of the second comparator 708 that detects the change of the signal becomes "1", the estimated speed (stored at n)

) Value moves to (n + 1). That is, the estimated speed (

Each time " 1 " is input as an output of the second comparator 708 that senses a change in the < RTI ID = 0.0 > 1, < / RTI >

) Value (data) is stored in the storage location of the address number increased by one. Then, when the output from the first comparator 704 that detects the change in the detection rotation speed W _mMT becomes 1, the third storage unit 710 stores all estimated speeds stored up to now.

By adding the values of

Outputs the estimated speed inputted from the speed estimator 518 at the present time (current).

) Is stored in the storage location of the first address.

The division operator 711 is connected to the output terminal of the counter 709 and the output terminal of the third storage unit 710 so that the sum of values of all estimated speeds stored up to the present time output from the third storage unit 710 (

) Divided by the number of inputs (n)

) Is calculated.

The third subtractor 712 is connected to the output terminal of the detection rotation speed calculator 516 and the output terminal of the division calculator 711 to divide the detection calculator 711 from the detection rotation speed W _mMT from the detection rotation speed calculator 516. Estimated speed average value

) By subtracting

) Is calculated.

On the other hand, the operation of the speed estimation device for a motor drive system having a speed sensor according to the present invention will be described with reference to FIGS.

The motor speed estimation by the speed estimator 518, which corresponds to the features according to the invention and is connected to the motor drive system shown in FIG. 1 and the detailed functional block configuration shown in FIG. 2, defines the motor speed. It can be derived from Equation (1) below.

In Equation (1), ω _m is the motor speed, τ _d is the load (disturbance) torque applied to the motor shaft, τ _m is the motor torque, and J is the inertia of the motor 502. In addition, the load torque in Equation (1) assumes that there is no change between the time the observer computes (from hundreds of microseconds to several milliseconds).

Is the derivative operator.

Using the equation (1) and the detection rotation speed W _mMT , which is the output of the detection rotation speed calculator 516, the rotation speed of the motor 502 is low so that the pulse output from the incremental encoder 503 of FIG. By constructing an observer (speed estimator) for estimating speed when there is none, the estimated speed and estimated load torque can be obtained from Equation (2) below. Equation (2) below shows the estimated speed (

) And an equation for estimating the speed and the load torque by using an error between the detection rotation speed W _mMT , which is the output of the detection rotation speed calculator 516.

In formula (2)

Is estimated speed

Is the estimated load torque, and k ₁ and k ₂ are the estimator (observer) gains, which can be obtained by the following equation (3).

In Equation (3), ω ₀ is the response of the estimator (observer).

The estimated load torque in (2)

Assuming that the initial value of) is 0 and Laplace transforms the estimated load torque in Eq. (2), it is as Equation (4), where s is the Laplace operator.

Assuming that the initial value of the estimated speed is 0 in Equation (2), Laplace transforming the portion of the estimated speed in Equation (2) and then substituting Equation (4) yields

here,

Is the estimated speed,

Is the integrator, J is the inertia of the motor,

Silver electric motor torque,

Is estimated load torque, k1 and k2 are gain,

Is the detected rotation speed.

The configuration of the speed estimator 518 of Fig. 2, which is a feature of the present invention, was obtained based on Equation (5) above.

In Fig. 2, the estimation error calculating unit 601 is an estimation error calculating unit having an improved feature of the present invention.

) And an estimated error that minimizes the difference between the detection rotation speed W _mMT output by the detection rotation speed calculator 516

) Is calculated.

The first multiplier 602 calculates the motor torque τ _m by multiplying the torque component current i _q , which is one of the two inputs of the speed estimator 518, by the motor torque constant K _t .

The first integrator 603 is an integrator having an estimator (observer) gain k ₂ of Equation (3), and an estimation error (

) Is multiplied by the estimator (observer) gain k ₂ and then integrated to perform the calculation of equation (4).

) Is calculated.

The second multiplier 604 and the third multiplier 605 each have a motor torque (

) And estimated load torque (

)on

Multiply the gain (gain obtained by the reciprocal of motor inertia) to prepare for calculation (5).

The fourth multiplier 606 also estimates the error (

) And multiply the gain k ₁ to prepare the equation (5).

The calculator 607 performs the operation in the curly braces of equation (5).

The second integrator 608 finally integrates the estimated speed

) Is calculated.

The calculation of the speed estimator (observer) is performed in synchronization with the speed detection period, and the estimation operation is performed by reflecting the amount of movement of the motor rotor during the speed detection period. At this point, when the new detection speed is input, the estimated speed tracks the actual speed by calculating the error between the actual speed and the estimated speed of the motor. In the prior art, the actual speed used for the estimation calculation is the instantaneous speed. The error of the estimation operation occurred while the average speed with the detection error was used, but the present invention does not compare the average speed and the instantaneous estimated speed, but the average speed and the estimated speed (

It is characterized by minimizing the error of estimation operation by comparing the average value of).

Average speed and estimated speed that minimize the error of the estimated operation (

Estimated error comparing the mean value of

Will be described with reference to FIG. 3, which is a detailed functional block diagram.

As a storage device, the first storage unit 701 periodically _{receives the} detection rotation speed W _mMT from the detection rotation speed calculator 516 and stores it until the next value (new value) is input. When the detected rotation speed input and output by the first storage unit 701 is W _mMT (n), the detection rotation speed input during the previous detection period and output by the first storage unit 701 is W _mMT (n-1). ) A first subtractor 702 calculates a difference between the detected rotational speed _mMT W (n-1) in the previous detection cycle and the detected rotational speed _mMT W (n) for the current detection cycle.

The first absolute value calculator 703 performs an absolute value operation as shown in Equation (6) below.

The first comparator 704 is the speed difference,

If the value of is greater than or equal to the predetermined value, '1' is output. If the value is less than the predetermined value, '0' is output to detect the change in the input value, that is, the detection speed W _mMT .

The second storage unit 705, the second subtractor 706, the second absolute value calculator 707, and the second comparator 708 are the first storage unit 701, the first subtractor 702, and the first absolute value, respectively. By performing the same operation as the value calculator 703 and the first comparator 704,

) Detects a change.

Counter 709 is estimated speed (

In response to the output from the second comparator 708 detecting the change of) and the output from the second comparator 708 is '1', the counter value is increased by one, and the change in the detection rotation speed (W _mMT ) is increased. If the output from the first comparator 704 is detected as '1' and the counter value is increased to the present as a counter output, the counter value is set to '1'. Initialize

The third storage unit 710 is a mass storage device and has an estimated speed (

Has a function of continuously storing the input value or clearing the stored value in synchronization with the first comparator 704 and the second comparator 708 that receive a change in the detected rotational speed and the estimated speed from the outside. have.

In more detail, assuming that the third storage unit 710 can store a total of m estimated speeds, there is a unit memory device from address 1 to m internally.

When the output of the second comparator 708 detecting the change of) becomes '1', the value stored at address (n) moves to (n + 1). Then, when the output of the first comparator 704 that detects the change in the detected rotational speed W _mMT becomes '1', the third storage unit 710 adds all the values stored so far to all the estimated speed values. Sum of

) And save the entered value at the first address.

The division operator 711 _adds the sum of the estimated speeds inputted at the time when the new detected rotational speed W _mMT is inputted (

) Is divided by the input number n and the average value of the estimated speed (

) Is calculated.

The third subtractor 712 is the average value of the estimated speed from the detected rotation speed W _mMT (

).

Since the speed estimation apparatus of the present invention by the estimation error calculation unit of FIG. It is possible to minimize the speed estimation error.

Therefore, the speed estimator 518 can increase the degree of speed control through the speed estimation even in the area where the speed detection is not performed in the low speed region. By using Equation (12), it is possible to reduce the estimation error, thereby enabling precise speed control.

Therefore, the speed estimator 518 according to the present invention can improve the accuracy of the speed control through accurate speed estimation even when speed detection is not performed in the low speed region. In addition, it is possible to obtain an effect that it becomes possible to minimize the estimation error in the low-speed speed estimation.

The configuration of the speed estimating apparatus for an electric motor drive system according to the present invention as described above has been described as a hardware configuration. However, the described configuration can be implemented by a software program by a person skilled in the art. It will be understood that the software can be configured.

1 is a system configuration diagram showing an overall system configuration of a motor drive system including a speed estimating apparatus according to the present invention,

2 is a functional block diagram showing a detailed configuration of only the speed estimating apparatus according to the present invention,

FIG. 3 is a functional block diagram illustrating a detailed configuration of the estimation error calculator of FIG. 2.

* Explanation of symbols on the main parts of the drawings

501: inverter 502: electric motor

503: incremental encoder 504: subtractor

505: speed control device 506: subtractor

507: subtractor 508: torque current controller

509: flux current controller 510: current controller

511: voltage controller 512a, 512b, 512c: phase current sensor

513: three-phase to two-phase converter 514: pulse amplifier

515: multiplier 516: detection speed calculator

517: flux component current command calculator 518: speed estimator

601: estimation error calculating unit 602: first multiplier

603: first integrator 604: second multiplier

605: third multiplier 606: fourth multiplier

607: operator 608: second integrator

701: first storage unit 702: first subtractor

703: first absolute value operator 704: first comparator

705: second storage unit 706: second subtractor

707: second absolute value operator 708: second comparator

709: Counter 710: third storage unit

711: division operator 712: third subtractor

Claims

A speed estimating apparatus for an electric motor drive system having a speed sensor,

A speed estimator having an estimation error calculating unit for calculating the estimation error based on the average value of the estimation speeds so as to reduce the estimation error in the low speed calculation. Estimation device.

The method of claim 1,

The speed estimator,

An estimation error calculator configured to calculate an estimation error based on the detected rotation speed and the estimation speed;

A first multiplier that multiplies the torque component current by a motor torque constant to calculate motor torque;

A first integrator that multiplies the estimation error by a first gain and then integrates to calculate a load torque estimate;

A second multiplier configured to multiply the motor torque output by the first multiplier by the inverse of the inertia of the motor;

A third multiplier for multiplying the inverse of the inertia of the motor by the load torque estimate output by the integrator;

A fourth multiplier that multiplies the estimation error by a second gain and outputs the multiplier;

The motor torque output by the second multiplier is multiplied by the inverse of the inertia of the motor and the estimated error output by the fourth multiplier is multiplied by a second gain, and the load torque estimate output by the third multiplier is calculated. An operator for subtracting and multiplying the product of the inverse of the inertia; And

And a second integrator configured to calculate an estimated speed by integrating a value output by the calculator.

The method of claim 2,

The estimation error calculation unit,

A first storage unit which periodically receives the detected rotational speed of the motor and stores and outputs a new detected rotational speed until a new detected rotational speed is input;

A first subtractor for calculating a difference between the detection rotation speed in a current detection period and the detection rotation speed in a previous detection period;

A first absolute value calculator outputting an absolute value of a value output by the subtractor;

Outputting 1 when the absolute value calculator outputs a value greater than or equal to a predetermined value, and outputs 0 when the absolute value calculator output value is smaller than a predetermined value to detect a change in the detected rotation speed. 1 comparator;

A second storage unit which periodically receives the estimated speed and stores and outputs the next estimated speed until a next estimated speed is input;

A second subtractor for calculating a difference between the estimated speed in a current detection period and the estimated speed before one detection period;

A second absolute value calculator outputting an absolute value of the value output by the subtractor;

A second comparator for detecting a change in the estimated speed by outputting 1 when the value output by the absolute value operator is greater than or equal to a predetermined value, and outputting 0 when the value output by the absolute value operator is smaller than a predetermined value. ;

Input the output value from the second comparator to increase the counter value by 1 when the output value of the second comparator is 1, and input the output value from the first comparator to the counter value when the output value of the first comparator is 1 A counter for outputting an increased counter value up to now and initializing the internal counter value to 1;

When the output from the first comparator reaches 1, the estimated speed inputted is stored, and all the estimated speeds stored up to now are summed and output, and the previously stored speeds are cleared. A third storage unit for storing the value of in a first storage location;

A division calculator for dividing the sum of all estimated speeds stored up to now output from the storage unit by the number of inputs to calculate an estimated speed average value;

And a third subtractor which calculates an estimation error by subtracting an estimated speed average value output from the division calculator from the detected rotation speed.

The method of claim 1,

The estimated speed is obtained by the following equation 5,