KR100845109B1 - Method for Starting of Sensorless Motor - Google Patents

Abstract

The present invention relates to an initial starting method of a sensorless motor that compensates the stator's resistance during initial startup so as to produce a rated torque during initial startup of the sensorless motor.

An initial start method of a sensorless motor according to the present invention includes: a power supply step of applying power to a sensing motor in order to excite a stator of the sensorless motor; A woman completion determination step of periodically determining whether the woman of the stator is completed; A d-axis voltage measuring step of measuring a voltage of the d-axis using the d-axis current and the feedback current of the sensorless motor when the excitation is not completed in the excitation completion determination step; A stator resistance compensation value calculating step of calculating a stator resistance compensation value by comparing the d-axis voltage measured in the d-axis voltage measuring step with a d-axis reference voltage; Compensation voltage calculation step of calculating a compensation voltage value using the stator resistance compensation value calculated in the stator resistance compensation value calculation step, when the excitation is completed in the excitation completion determination step, and the compensation voltage calculated in the compensation voltage calculation step Compensation voltage generation step of generating a.

Sensorless Motor, Stator, Resistance, Compensation

Description

Method for Starting of Sensorless Motor

1 is a block diagram of a method for initially starting a sensorless motor according to the prior art.

2 is a block diagram of an initial starting method of a sensorless motor according to an embodiment of the present invention;

3 is a flow chart illustrating a method for initially starting a sensorless motor according to an embodiment of the present invention.

4 is a diagram illustrating a current waveform and a d-axis voltage reference waveform in a state of operating from a moment of applying power to 10 Hz by an initial start method of a sensorless motor according to an embodiment of the present invention.

FIG. 5 is a diagram showing current waveforms when forward and reverse driving are performed from the moment when the output frequency is applied to 60 Hz according to the initial starting method of the sensorless motor according to the embodiment of the present invention. .

Description of the main symbols in the drawings

1: Stator resistance 2: d-axis current at no load

3: estimated inductance 4: q-axis measurement current

5: d-axis compensation voltage 6: d-axis feedback current

7: PI 11: current waveform

12: d-axis reference voltage waveform 101: stator resistance

102: d-axis current at no load 103: estimated inductance

104: feedback current 105: d-axis reference voltage

The present invention relates to an initial start method of a sensorless motor, and more particularly, to prevent a phenomenon in which a flux of magnetic force is insufficient due to the resistance of a stator during initial start of a sensorless motor. The present invention relates to an initial starting method of a sensorless motor that compensates the resistance of the sensorless motor so as to generate a rated torque during the initial starting of the sensorless motor.

In general, various industrial equipment is provided with a motor to generate a driving force.

These motors adjust the torque generated from the motor by sensing the current supplied, the number of rotations of the rotating shaft, etc. and compensating or controlling it.

For example, an induction motor, a type of motor, receives magnetic flux from a permanent magnet attached to the rotor, so it is necessary to always know the exact position information of the rotor for vector control. Therefore, in order to obtain the position information of the motor rotor, a sensor such as a resolver, an absolute encoder, or the like must be attached to the shaft of the motor. However, sensors such as resolvers, absolute encoders and the like are generally expensive and have the disadvantage that separate complex hardware must be attached to the controller. In addition, the sensors are limited in the use environment because they are greatly affected by the surrounding environment such as vibration and humidity, and the sensor is attached to the rotating shaft of the motor, thereby causing additional problems such as increase in size and inertia of the motor.

In order to avoid such a problem, a sensorless motor that can control to generate a desired torque using each parameter value of the motor without using a sensor for identifying the position of the motor rotor has been widely used.

FIG. 1 is a block diagram of a method of making a d-axis voltage reference (Vd_refence), which shows a method of initializing a sensorless motor according to the prior art.

In FIG. 1 of the prior art, Rs_est 101 is a stator resistance value estimated using a motor constant parameter, Id_Rate 102 is a no-load current value of the motor as a reference value of the d-axis current, and ω Lδ 103 is a motor constant. It is an inductance value obtained by estimating a parameter, and Iq_Flt 104 is a q-axis current value input from the ammeter CT.

Here, under the above conditions, the value obtained by multiplying the value of Id_Rate 102 and Rs_est (101) is calculated by multiplying the fed back value of Id_flt 104 and ωLδ 105 and outputting the d-axis voltage reference 105. It is an initial starting method of a sensorless motor of the prior art.

The Rs_est 101 value and the ω Lδ 103 value are obtained at the beginning of driving of the sensorless motor by an estimation algorithm using the motor constant parameter. Since the time constant of the magnetic flux in the induction motor is considerably slower than the time constant of the torque component current (Iq), similar to other excitation DC motors, the torque component is controlled in real time while the torque component is controlled in real time with the constant magnetic flux that is difficult to control. Control the speed or torque of the lease motor.

That is, the initial driving of the motor applies the q-axis reference voltage (Vq_reference) as '0' at a time when the magnetic flux does not reach a steady state, and controls the d-axis voltage to constantly control the magnetic flux.

Since the magnetic flux is not completely formed in the initial stage of driving of the motor, the time until the magnetic flux reaches the normal value by using the PI controller 7 is determined by the value of the d-axis rated current and the fed-back d-axis current 6. The d-axis reference voltage (Vd_reference) is obtained by applying the compensation voltage (Vdead) for the dead time, it can be expressed by the following equation.

Vd_reference = Rs_est * Id_rate + Vdead

After the motor is driven and the magnetic flux is completely formed, in order to keep the magnetic flux constant, the following equations must be satisfied.

Vq_reference = Rs_est * Iqs + ω * Lδ * Ids

Vd_reference = Rs_est * Ids-ω * Lδ * Iqs

By the way, in the above equation, the reference voltage Vq_reference for the q-axis is generated by feedback of the Iqs and Ids current values by a closed loop, whereas the reference voltage Vd_reference for the d-axis is applied in an open loop. Therefore, since the d-axis reference voltage Vd_reference is obtained by applying a voltage reference, precise control is not easy when an error occurs.

That is, the driving method of the sensorless motor of the prior art as described above has the advantage of easy implementation, but there was a problem that the compensation by the dead time until the normal state after the power is applied is not sure.

In addition, the voltage reference value calculated and applied at the time of formation of the magnetic flux is different from the voltage reference value calculated at initial startup, or a voltage reference calculated incorrectly due to a change in the motor constant value is applied to apply the rated torque designed at startup. It doesn't happen.

In addition, this is difficult to start smoothly, the current value is unstable (hunting) to find a stable current value (damping) damage to the motor, it will affect other equipment connected to it.

The present invention has been invented to solve the above problems, the sensor for compensating the resistance value of the stator to compensate for the voltage required for the start of the stator to compensate for the insufficient magnetic flux by the stator resistance during initial startup in the sensorless motor An object of the present invention is to provide a method for initial starting a lease motor.

In order to achieve the above object, the initial start-up method of the sensorless motor of the present invention, the power supply step of applying power to the sensing motor to excite the stator of the sensorless motor; A woman completion determination step of periodically determining whether the woman of the stator is completed; A d-axis voltage measuring step of measuring a voltage of the d-axis using the d-axis current and the feedback current of the sensorless motor when the excitation is not completed in the excitation completion determination step; A stator resistance compensation value calculating step of calculating a stator resistance compensation value by comparing the d-axis voltage measured in the d-axis voltage measuring step with a d-axis reference voltage; Compensation voltage calculation step of calculating a compensation voltage value using the stator resistance compensation value calculated in the stator resistance compensation value calculation step, when the excitation is completed in the excitation completion determination step, and the compensation voltage calculated in the compensation voltage calculation step Compensation voltage generation step of generating a.

In the compensation voltage calculation step, the generated compensation voltage value is characterized by satisfying the following equation.

Vq_reference = Rs_est * Iqs + ω * Lδ * Ids

Vd_reference = Rs_est * Ids-ω * Lδ * Iqs + ωSL_boost

However, 'ωSL_boost' corresponding to the compensation voltage value to be applied to the d-axis voltage is determined by the proportional relationship shown in the following equation. That is, it is obtained by multiplying the resistance compensation value of the stator by the frequency.
ωSL_boost = SL_boost * {(Base Frequency-Current Frequency) / Base Frequency}

Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment of the initial start method of the sensorless motor of the present invention.

Figure 2 is a block diagram showing an initial start method of the sensorless motor according to the present invention, Figure 3 is a flow chart according to the initial start method of the sensorless motor according to the present invention, Figures 4 and 5 according to the present invention The figure which shows the state at the time of operating a sensorless motor by the initial starting method of a sensorless motor.

As shown in FIG. 3, according to the initial starting method of the sensorless motor according to the present invention, power is first applied to operate the sensorless motor (S110). When the power is applied, the stator is excited in the sensorless motor and rotated by the interaction of the rotor made of permanent magnets. When the power is applied to the sensorless motor, the stator starts to be excited and the rotor starts to rotate. do.

When power is applied to the sensorless motor and starts to operate, the sensorless motor periodically determines whether the excitation of the stator is completed (S120). If it is determined that the excitation is completed periodically, if it is determined that the excitation is not completed, the d-axis voltage is measured (S130), and the compensation for compensating the resistance value of the stator by calculating the measured d-axis voltage and d-axis reference voltage In operation S140, when it is determined that the excitation is completed, a compensation voltage value is calculated using the stator resistance compensation value (S150), and a compensated voltage is generated (S160).

When power is applied and the sensorless motor starts to rotate, at the same time, the d-axis voltage value is measured through the d-axis current and the feedback current. Since the excitation of the stator is not completed immediately after the power is applied, the step of measuring the d-axis voltage value is preferentially performed.

Measuring the voltage value of the sensorless motor through the d-axis current and the feedback current (S130) is measured using the d-axis reference current (Id_rate, 2) and the feedback current (Id_feedback, 6) of the d-axis current do.

The d-axis reference current (Id_rate) is usually the no-load current amount of the sensorless motor, and inputs the feedback (Id_feedback) of the d-axis reference current (Id_rate) and the d-axis current to the PI controller 7, and by the motor constant estimation algorithm Alternatively, the d-axis voltage is measured by calculating with the stator resistance value Rs_est, 1 provided when the motor is manufactured.

As described above, after the d-axis current is measured (S130), a compensation value for compensating the stator resistance is calculated (S140).

At this time, the compensation value SL_Boost for compensating the stator resistance is a difference between the d-axis voltage value of the sensorless motor obtained above and the formula for generating magnetic flux to excite the stator (Vd_reference = Rs_est * Ids), where The obtained compensation value (SL_Boost) is actually made only in the initial female section here.

That is, as shown in FIG. 2, the value calculated by the PI controller 7 to calculate the feedback (Id_feedback) of the d-axis reference current Id_Rate 2 and the d-axis current, and a formula for generating magnetic flux (Vd_reference = Rs_est * Ids) is calculated and the difference is a compensation value for compensating the stator's resistance.

On the other hand, after the excitation of the stator is completed, the compensation voltage value of the sensorless motor is calculated by the equation (S140).

'ωSL_boost' corresponding to the compensation voltage value to be applied to the d-axis voltage is determined by a proportional relationship shown by the following equation. That is, it is obtained by multiplying the resistance compensation value of the stator by the frequency.

ωSL_boost = SL_boost * {(Base Frequency-Current Frequency) / Base Frequency}

On the other hand, since the magnetic flux is not completely formed immediately after the sensorless motor is operated, the amount of voltage to be compensated for is large.However, when the Sensellis motor is operated, the magnetic flux remains normal after a certain period of time. Since they become equal, as time passes, the amount of voltage to be compensated for is gradually reduced, and when the sensorless motor is operated and stable, the amount of voltage to be compensated for does not occur.

At this time, the voltage generated by the operation is added to the compensation voltage value of the above terms to generate the d-axis, q-axis voltage by the following equation.

Vq_reference = Rs_est * Iqs + ω * Lδ * Ids

Vd_reference = Rs_est * Ids-ω * Lδ * Iqs + ωSL_boost

In this case, as described above, the SL_boost value is a value generated in the initial excitation period, and a voltage value compensated by linking this value with an output frequency is determined.

As described above, after the compensation voltage is calculated, by generating the d-axis voltage and the q-axis voltage (S160), by applying a voltage reflecting the compensation value to the sensorless motor, the rated torque stably during initial start-up of the sensorless motor To make it work.

By the method of the initial start of the sensorless motor according to the present invention as described above, looking at the waveform when the sensorless motor is operated, as shown in Figs.

FIG. 4 shows the current waveform 11 and the d-axis voltage reference waveform 12 in the state where the output frequency is operated from the time of applying power to 10 Hz, and hunting of current while the stator is initially excited. It can be seen that it operates with limited current without generating) and generates rated torque even in low speed operation.

In addition, Fig. 5 shows the current waveform 11 when the forward frequency and the reverse direction are operated from the moment when the output frequency is applied to the power to 60 Hz, and even at this time, no hunting of the current occurs at the initial startup.

According to the initial start method of the sensorless motor according to the present invention as described above, by compensating the voltage required for the start of the stator at the initial start of the sensorless motor, it is possible to generate a rated torque at the initial start of the sensorless motor , Can work stably.

In addition, since the same hardware is used in the conventional sensorless motor, it is possible to achieve an improvement in performance without additional cost.

Claims (2)

A power supply step of applying power to the sensing motor in order to excite the stator of the sensorless motor; A woman completion determination step of periodically determining whether the woman of the stator is completed; A d-axis voltage measuring step of measuring a voltage of the d-axis using the d-axis current and the feedback current of the sensorless motor when the excitation is not completed in the excitation completion determination step; A stator resistance compensation value calculating step of calculating a stator resistance compensation value by comparing the d-axis voltage measured in the d-axis voltage measuring step with a d-axis reference voltage; A compensation voltage calculating step of calculating a compensation voltage value using the stator resistance compensation value calculated in the stator resistance compensation value calculating step when the excitation is completed in the exciting completion determination step; And a compensation voltage generation step of generating a compensation voltage calculated in the compensation voltage calculation step. The method of claim 1, In the compensation voltage calculation step, The generated compensation voltage value satisfies the following equation. Vq_reference = Rs_est * Iqs + ω * Lδ * Ids Vd_reference = Rs_est * Ids-ω * Lδ * Iqs + ωSL_boost ΩSL_boost = SL_boost * {(Base Frequency-Current Frequency) / Base Frequency}

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