JP6962274B2 - Inverter - Google Patents

Description

The present invention relates to position sensorless control of a PM motor, and more particularly to a vibration suppression method of a current drawing method.

In a motor drive system using an inverter, position sensorless control that operates without using a magnetic pole position detector of a permanent magnet type synchronous motor (PM motor) has been put into practical use.

Many types of position sensorless control methods have been developed as methods for controlling speed and torque by this position sensorless control. As one of the methods, a method is used in which a current of a certain magnitude and a constant amplitude is passed, and the frequency is gradually changed to maintain the synchronous pull-in state while forcibly following the current to start the rotor. Has been done. Here, this is called a current drawing method. FIG. 5 shows a control block using the current drawing method. As a prior art document of the current drawing method, for example, Non-Patent Document 1 is disclosed.

[Current draw-in method]
As shown in FIG. 5, in the integrator 1, the velocity command is integrated and converted into a phase. In the three-phase / two-phase converter 2, the current detection value of the inverter is converted into the d-axis and q-axis current detection values on the rotational coordinates based on this phase. The current control unit ACR inputs a lead-in current command as a d-axis current command and zero as a q-axis current command. The current control unit ACR outputs the d-axis and q-axis voltage commands so that there is no deviation between the d-axis and q-axis current commands and the d-axis and q-axis current detection values.

The two-phase / three-phase converter 3 performs two-phase / three-phase conversion based on the phase output by the integrator 1 for the d-axis and q-axis voltage commands, and generates U-phase, V-phase, and W-phase voltage commands. The PWM controller PWM generates a gate signal (on / off command signal) of each switching element in the inverter by comparing the triangular wave carrier signal with the U-phase, V-phase, and W-phase voltage commands. Then, the voltage is output from the inverter and applied to the motor (not shown).

As a result, the current according to the lead-in current command flows to the motor, and the magnetic poles of the rotor are attracted to the phase in which the draw-in current is flowing. Since the lead-in current phase flows to the phase in which the speed command is integrated, the current phase rotates according to the speed command, and the motor is rotated while the magnetic poles are attracted to this current phase.

However, the current drawing method has the following problems (1) and (2).

(1) Even if the current amplitude is kept constant, the torque fluctuates as a sine function of the phase difference between the magnetic pole shaft and the current shaft, so that the behavior resembles that of an elastic shaft in which the torque changes due to shaft twisting. Therefore, when a transient phenomenon such as load torque fluctuation occurs, velocity vibration (shaft torsional vibration) that resonates with the moment of inertia occurs.

If this shaft torsional vibration occurs, there is a problem that the PM motor without a damper winding has no braking effect and the vibration continues. This shaft torsional vibration lowers the quality of torque output to the load and may adversely affect the mechanical system such as coupling.

(2) When the above-mentioned shaft torsional vibration occurs, the torque pulsation for the shaft torsion is further added to the load torque. Therefore, if the current amplitude is not set large, the maximum torque may be exceeded and step-out may occur. There is. In order to prevent this, it is necessary to pass a current 1.5 to 2 times larger than the current required by normal vector control. As a result, a large capacity inverter is required.

As a method for solving the above problems, Patent Document 1 that suppresses the shaft torsional vibration when the shaft torsional vibration as shown in FIG. 6 occurs is disclosed.

[Patent Document 1]
FIG. 6 shows a control block diagram of Patent Document 1. The same parts as those in FIG. 5 are designated by the same reference numerals, and the description thereof will be omitted. Patent Document 1 (FIG. 6) is obtained by adding the vibration suppression unit 14 to FIG.

The d-axis voltage command output by the current control unit ACR is applied to a bandpass filter BPF (Band-pass filter), and only the vibration component of the d-axis voltage command caused by the shaft vibration is extracted. The multiplier 4 multiplies the vibration component extracted by the bandpass filter BPF by the gain G. The function unit 10 calculates the sign (polarity) of the speed command.

The multiplier 11 multiplies the output of the multiplier 4 by the sign polarity of the speed command, and outputs it as a vibration suppression signal for correcting the speed command. The subtractor 13 subtracts the vibration suppression signal from the speed command. This makes it possible to suppress shaft vibration in a very simple manner without adding complicated processing.

JP-A-2017-85720

Toshikatsu Igarashi, Girder Liu Jiang "A study of the pull-in current value in the magnetic pole alignment of PM motors by the current pull-in method", 2017 IEEJ National Convention, 4-153

However, Patent Document 1 may not have the effect of suppressing vibration when shaft vibration occurs at zero speed or extremely low speed. In Patent Document 1, the vibration suppression unit 14 is controlled by using the polarity of the speed command. On the other hand, at zero speed or extremely low speed, the polarity of the speed command and the polarity of the actual rotation speed of the motor (that is, the direction of rotation) often do not match. If the polarities of the two do not match in this way, the vibration suppression unit 14 cannot be properly controlled, so that vibration suppression cannot be performed.

Furthermore, in this case, when the magnetic pole is pulled in for the first time when the current is pulled in, a DC current with a frequency of zero flows, so if vibration occurs when the magnetic pole is pulled in, the starting torque and the torque for the vibration are required at the start of acceleration of the motor. Therefore, there is a risk of step-out.

From the above, it is an issue for the inverter to suppress the vibration of the rotational speed of the motor at zero speed or extremely low speed and to suppress the step-out of the motor.

The present invention has been devised in view of the above-mentioned conventional problems, and one aspect thereof is based on the phase obtained by integrating the value obtained by subtracting the vibration suppression signal from the speed command in the inverter for driving the permanent magnet type synchronous electric motor. A three-phase / two-phase converter that converts the current detection value into three-phase / two-phase and outputs the d-axis and q-axis current detection values, a d-axis current command and a q-axis current command that are lead-in current commands, and the above. Based on the deviation from the d-axis and q-axis current detection values, the current that generates the d-axis and q-axis voltage commands so that the d-axis and q-axis current detection values follow the d-axis and q-axis current commands. A control unit, a two-phase / three-phase converter that converts the d-axis and q-axis voltage commands into three-phase voltage commands based on the phase, and each switching in the inverter based on the three-phase voltage commands. The PWM control unit that generates the gate signal of the element, the first multiplier that multiplies the gain Gd by the vibration component caused by the shaft vibration of the d-axis voltage command, and the vibration component caused by the shaft vibration of the q-axis voltage command. A second multiplier that multiplies the value that caused the first-order delay by the gain Gq, and when the absolute value of the speed command is equal to or greater than the threshold value, the d-axis gain is set to 1 and the q-axis gain is set to 0, and the absolute value of the speed command is set to 0. A gain adjusting unit that sets the d-axis gain to 0 and the q-axis gain to 1 when the value is smaller than the threshold value, and a value obtained by multiplying the output of the first multiplier by the d-axis gain and the sign polarity of the speed command. The second multiplier is provided with a value obtained by multiplying the output of the second multiplier by the q-axis gain, and an adder that adds and outputs the vibration suppression signal.

Further, as another embodiment, in the inverter for driving the permanent magnet type synchronous electric motor, the current detection value is converted into three-phase / two-phase based on the phase obtained by subtracting the vibration suppression signal from the speed command, and the d-axis, Based on the deviation between the three-phase / two-phase converter that outputs the q-axis current detection value, the d-axis current command and the q-axis current command that are the lead-in current commands, and the d-axis and q-axis current detection values. The current control unit that generates the d-axis and q-axis voltage commands and the d-axis and q-axis voltage commands are set to the phase so that the d-axis and q-axis current detection values follow the d-axis and q-axis current commands. A two-phase / three-phase converter that converts to a three-phase voltage command based on this, a PWM control unit that generates a gate signal for each switching element in the inverter based on the three-phase voltage command, and the q-axis voltage. It is characterized by including a vibration suppression unit that calculates the vibration suppression signal by multiplying a value that causes a primary delay in the vibration component caused by the command shaft vibration by a gain Gq.

Further, as another embodiment, in the inverter for driving the permanent magnet type synchronous electric motor, the current detection value is converted into three-phase / two-phase based on the phase obtained by subtracting the vibration suppression signal from the speed command, and the d-axis, Based on the deviation between the three-phase / two-phase converter that outputs the q-axis current detection value, the d-axis current command and the q-axis current command that are the lead-in current commands, and the d-axis and q-axis current detection values. The current control unit that generates the d-axis and q-axis current commands and the d-axis and q-axis voltage commands are set to the phase so that the d-axis and q-axis current detection values follow the d-axis and q-axis current commands. A two-phase / three-phase converter that converts to a three-phase voltage command based on this, a PWM control unit that generates a gate signal for each switching element in the inverter based on the three-phase voltage command, and the d-axis voltage. The first multiplier that multiplies the vibration component caused by the shaft vibration of the command by the gain Gd, and the second multiplier that multiplies the value that causes the first-order delay in the vibration component caused by the shaft vibration of the q-axis voltage command by the gain Gq. When the absolute value of the speed command is equal to or less than the first threshold value, the q-axis gain is set to 1, the d-axis gain is set to 0, and the absolute value of the speed command is larger than the first threshold value and larger than the second threshold value. When is also small, the q-axis gain is gradually decreased from 1 to 0 and the d-axis gain is gradually increased from 0 to 1 in accordance with the increase in the absolute value of the speed command. When the value is equal to or greater than the second threshold value, the d-axis gain is set to 1 and the q-axis gain is set to 0. The output of the first multiplier is multiplied by the d-axis gain and the sign polarity of the speed command. It is characterized by including an adder that adds the value obtained by multiplying the output of the second multiplier by the q-axis gain and outputs the vibration suppression signal.

According to the present invention, in the inverter, it is possible to suppress the vibration of the rotational speed of the motor at the time of zero speed or the extremely low speed, and to suppress the step-out of the motor.

The block diagram which shows the control composition of the inverter in an embodiment. The figure which shows the d-axis gain and the q-axis gain in an embodiment. A time chart showing a simulation result of Patent Document 1. A time chart showing the simulation results of the embodiment. The block diagram which shows the control composition of the inverter which used the conventional current drawing method. The block diagram which shows the control structure of the inverter of Patent Document 1. FIG.

Hereinafter, embodiments 1 and 2 of the inverter according to the present invention will be described in detail with reference to FIGS. 1 to 4.

[Embodiment 1]
FIG. 1 shows a control block diagram of the inverter according to the first embodiment. The integrator 1 integrates the value obtained by subtracting the vibration suppression signal described later from the speed command and converts it into a phase. The three-phase / two-phase converter 2 outputs d-axis and q-axis current detection values obtained by converting the current detection value of the inverter into rotational coordinates based on this phase.

The current control unit ACR inputs a lead-in current command as a d-axis current command and zero as a q-axis current command. The current control unit ACR so that the d-axis and q-axis current detection values follow the d-axis and q-axis current commands based on the deviation between the d-axis and q-axis current commands and the d-axis and q-axis current detection values. Outputs d-axis and q-axis voltage commands.

The two-phase / three-phase converter 3 performs two-phase / three-phase conversion based on the phase output by the integrator 1 for the d-axis and q-axis voltage commands, and generates U-phase, V-phase, and W-phase voltage commands. .. The PWM control unit PWM generates a gate signal (on / off command signal) for each switching element in the inverter by comparing the U-phase, V-phase, and W-phase voltage commands with the triangular wave carrier signal, thereby causing a voltage from the inverter. Is output and applied to the electric motor (not shown).

The d-axis voltage command output by the current control unit ACR is applied to the first bandpass filter BPF1 (Band-pass filter), and only the vibration component of the d-axis voltage command caused by the shaft vibration is extracted. The first multiplier 4 multiplies the vibration component extracted by the first bandpass filter BPF1 by the gain Gd.

Further, the q-axis voltage command output by the current control unit ACR is applied to the second bandpass filter BPF2, and only the vibration component of the q-axis voltage command caused by the shaft vibration is extracted. Further, the vibration component is applied to a low-pass filter LPF (Low-pass filter) to cause a first-order delay. The second multiplier 5 multiplies the vibration component extracted by the low-pass filter LPF by the gain Gq.

The gain adjusting unit 6 adjusts the d-axis gain according to the speed command. When the absolute value of the speed command is equal to or greater than the threshold value, the d-axis gain is set to 1, and when the absolute value of the speed command is smaller than the threshold value, the d-axis gain is set to 0. The multiplier 7 multiplies the output of the multiplier 4 by the d-axis gain. The subtractor 8 subtracts the d-axis gain from 1 to calculate the q-axis gain. That is, when the absolute value of the speed command is equal to or greater than the threshold value, the q-axis gain is set to 0, and when the absolute value of the speed command is smaller than the threshold value, the q-axis gain is set to 1. The multiplier 9 multiplies the output of the multiplier 5 by the q-axis gain.

The function unit 10 calculates the sign polarity of the speed command. The multiplier 11 multiplies the output of the multiplier 7 by the sign polarity of the speed command output from the function unit 10. The adder 12 adds the output of the multiplier 9 to the output of the multiplier 11 and outputs it as a vibration suppression signal. The subtractor 13 subtracts the vibration suppression signal from the speed command and outputs it to the integrator 1.

When the PM motor rotates, velocity electromotive force is generated by the magnetic flux generated by the magnet of the rotor. Since this velocity electromotive force is generated in the q-axis direction, the q-axis voltage fluctuates when the velocity fluctuates. That is, the voltage component generated by the shaft vibration is superimposed on the q-axis voltage.

Therefore, the q-axis voltage command output by the current control unit ACR is applied to the second bandpass filter BPF2 in the same manner as the d-axis voltage command, and only the vibration component of the q-axis voltage command caused by the shaft vibration is extracted.

Further, the vibration component is applied to the low-pass filter LPF to cause a first-order delay. Although the second bandpass filter BPF2 and the lowpass filter LPF are described separately, they may be grouped together. The reason why the low-pass filter LPF is added is that the vibration of the q-axis voltage and the vibration of the velocity occur in substantially the same phase, and therefore, the vibration suppression effect can be obtained by causing the phase delay (ideally π / 2).

Gain Gq is applied to the vibration component of the q-axis voltage command applied to the low-pass filter LPF to obtain the vibration suppression signal based on the q-axis voltage command. The vibration suppression signal based on the q-axis voltage command obtained here is applied only to the zero speed to the extremely low speed range. When the speed at which the vibration suppression signal based on the d-axis voltage command in Patent Document 1 becomes effective, the vibration suppression signal based on the d-axis voltage command is switched to.

For this switching, the d-axis gain and the q-axis gain described below are used. When the absolute value of the speed command is equal to or greater than the threshold value, the d-axis gain is set to 1, the q-axis gain is set to 0, and when the absolute value of the speed command is smaller than the threshold value, the d-axis gain is set to 0 and the q-axis gain is set to 1. The vibration suppression signal is obtained by adding the value obtained by multiplying the vibration suppression signal based on the d-axis voltage command by the sign polarity of the d-axis gain and the speed command and the value obtained by multiplying the vibration suppression signal based on the q-axis voltage command by the q-axis gain. It should be output as.

As shown above, according to the first embodiment, it is possible to suppress the vibration of the rotational speed of the motor at zero speed or extremely low speed. As a result, the speed fluctuation and step-out of the motor can be reduced, so that the reliability of the motor drive system can be improved.

[Embodiment 2]
In the second embodiment, the vibration suppression signals obtained by the d-axis and q-axis voltage commands are multiplied by the d-axis gain and the q-axis gain as shown in FIG. 2, respectively, and added to the q-axis voltage command gradually. The vibration suppression signal based on the vibration suppression signal is switched to the vibration suppression signal based on the d-axis voltage command (see the speed command 2 → 3% gain in FIG. 2). By doing so, the vibration suppression signal at the time of gain switching is prevented from suddenly changing.

As shown in FIG. 2A, the d-axis gain is zero when the absolute value of the speed command is 2% or less of the first threshold value, and is the speed command when the absolute value of the speed command is larger than the first threshold value of 2%. The d-axis gain is increased according to the increase in the absolute value of the speed command at a rate of change such that the absolute value becomes 1 at the second threshold value of 3%. When the absolute value of the speed command is 3% or more of the second threshold value, the d-axis gain becomes 1.

As shown in FIG. 2B, the q-axis gain is 1 when the absolute value of the speed command is 2% or less of the first threshold value, and 1 when the absolute value of the speed command is larger than the first threshold value of 2%. The q-axis gain is reduced as the absolute value of the speed command increases at a rate of change such that the absolute value becomes zero at the second threshold value of 3%. When the absolute value of the speed command is 3% or more of the second threshold value, the q-axis gain becomes 0.

3 and 4 show the results of simulations carried out under the same conditions in Patent Document 1 and the second embodiment. At the start of operation, the current phase (control phase) through which the d-axis current flows and the actual magnetic pole position of the PM motor are shifted by 4 / 5π. The time of the zero velocity command for pulling in the magnetic pole is 0.5 sec, and the velocity command is changed from there to 0.1 pu in 0.1 sec.

In the simulation result of Patent Document 1 shown in FIG. 3, the current phase through which the d-axis current flows and the position of the magnetic pole position deviate from each other at the start of operation. Therefore, the magnetic poles are attracted to the current phase, but at that time, shaft vibration occurs and the vibration continues during the zero speed command, and the motor speed swings positively or negatively (0 to 0.6 s period). When the speed command rises, the vibration is converged only after the effect of suppressing the vibration is obtained.

On the other hand, in the simulation result using the control method of the second embodiment shown in FIG. 4, the magnetic poles are attracted to the current phase at the start of operation and vibration starts to occur, but the vibration almost disappears 0.3 sec after the start of operation. ing.

Further, in 0.5 to 0.6 s, the vibration suppression signal using the q-axis voltage command is switched to the vibration suppression signal using the d-axis voltage command, but the speed and current do not suddenly change at the time of switching. It is switching.

As shown above, according to the second embodiment, the same effects as those of the first embodiment are obtained. Further, since the vibration suppression signal using the q-axis voltage command is gradually switched to the vibration suppression signal using the d-axis voltage command, it is possible to suppress a sudden change in speed or current at the time of switching.

Although the above description has been made in detail only with respect to the specific examples described in the present invention, it is clear to those skilled in the art that various modifications and modifications can be made within the scope of the technical idea of the present invention. It goes without saying that such modifications and modifications fall within the scope of the claims.

The gain adjusting unit 6 shown in FIG. 1 may have a configuration in which (a) the d-axis side is always 0 and (b) the q-axis side is always 1, so that switching to the d-axis voltage command is not performed. .. In this case, the output of the multiplier 5 becomes a vibration suppression signal.

1 ... Integrator 2 ... Three-phase / two-phase converter ACR ... Current control unit 3 ... Two-phase / three-phase converter PWM ... PWM control unit BPF1, BPF2 ... 1st and 2nd bandpass filters 4 ... 1st multiplier LPF ... Low-pass filter 5 ... Second multiplier 6 ... Gain adjustment unit 7 ... Multiplier 8 ... Subtractor 9 ... Multiplier 10 ... Function unit 11 ... Multiplier 12 ... Adder 13 ... Subtractor 14 ... Vibration suppression unit

Claims (3)

In the inverter that drives the permanent magnet type synchronous motor
A three-phase / two-phase converter that converts the current detection value into three-phase / two-phase and outputs the d-axis and q-axis current detection values based on the phase obtained by integrating the value obtained by subtracting the vibration suppression signal from the speed command.
Based on the deviation between the d-axis current command and the q-axis current command, which are the lead-in current commands, and the d-axis and q-axis current detection values, the d-axis and q-axis current detection values are the d-axis and q-axis current commands. A current control unit that generates d-axis and q-axis voltage commands so as to follow
A two-phase / three-phase converter that converts the d-axis and q-axis voltage commands into three-phase voltage commands based on the phase.
A PWM control unit that generates a gate signal for each switching element in the inverter based on the three-phase voltage command.
A first multiplier that multiplies the gain Gd by the vibration component caused by the shaft vibration of the d-axis voltage command.
A second multiplier that multiplies the gain Gq by the value that caused the first-order delay in the vibration component caused by the shaft vibration of the q-axis voltage command.
When the absolute value of the speed command is equal to or greater than the threshold value, the d-axis gain is set to 1, the q-axis gain is set to 0, and when the absolute value of the speed command is smaller than the threshold value, the d-axis gain is set to 0 and the q-axis gain is set to 1. Gain adjustment unit and
The vibration suppression signal is obtained by adding the value obtained by multiplying the output of the first multiplier by the d-axis gain and the sign polarity of the speed command and the value obtained by multiplying the output of the second multiplier by the q-axis gain. With an adder that outputs as
An inverter characterized by being equipped with. In the inverter that drives the permanent magnet type synchronous motor
A three-phase / two-phase converter that converts the current detection value into three-phase / two-phase and outputs the d-axis and q-axis current detection values based on the phase obtained by integrating the value obtained by subtracting the vibration suppression signal from the speed command.
Based on the deviation between the d-axis current command and the q-axis current command, which are the lead-in current commands, and the d-axis and q-axis current detection values, the d-axis and q-axis current detection values are the d-axis and q-axis current commands. A current control unit that generates d-axis and q-axis voltage commands so as to follow
A two-phase / three-phase converter that converts the d-axis and q-axis voltage commands into three-phase voltage commands based on the phase.
A PWM control unit that generates a gate signal for each switching element in the inverter based on the three-phase voltage command.
A vibration suppression unit that calculates as the vibration suppression signal the value obtained by multiplying the value that caused the primary delay in the vibration component caused by the shaft vibration of the q-axis voltage command by the gain Gq.
An inverter characterized by being equipped with. In the inverter that drives the permanent magnet type synchronous motor
A three-phase / two-phase converter that converts the current detection value into three-phase / two-phase and outputs the d-axis and q-axis current detection values based on the phase obtained by integrating the value obtained by subtracting the vibration suppression signal from the speed command.
Based on the deviation between the d-axis current command and the q-axis current command, which are the lead-in current commands, and the d-axis and q-axis current detection values, the d-axis and q-axis current detection values are the d-axis and q-axis current commands. A current control unit that generates d-axis and q-axis voltage commands so as to follow
A two-phase / three-phase converter that converts the d-axis and q-axis voltage commands into three-phase voltage commands based on the phase.
A PWM control unit that generates a gate signal for each switching element in the inverter based on the three-phase voltage command.
A first multiplier that multiplies the gain Gd by the vibration component caused by the shaft vibration of the d-axis voltage command.
A second multiplier that multiplies the gain Gq by the value that caused the first-order delay in the vibration component caused by the shaft vibration of the q-axis voltage command.
When the absolute value of the speed command is equal to or less than the first threshold value, the q-axis gain is set to 1, the d-axis gain is set to 0, and the absolute value of the speed command is larger than the first threshold value and smaller than the second threshold value. As the absolute value of the speed command increases, the q-axis gain is gradually decreased from 1 to 0, the d-axis gain is gradually increased from 0 to 1, and the absolute value of the speed command is the second. A gain adjusting unit that sets the d-axis gain to 1 and the q-axis gain to 0 when the value is equal to or higher than the threshold value.
The vibration suppression signal is obtained by adding the value obtained by multiplying the output of the first multiplier by the d-axis gain and the sign polarity of the speed command and the value obtained by multiplying the output of the second multiplier by the q-axis gain. With an adder that outputs as
An inverter characterized by being equipped with.

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