JP6433411B2 - Synchronous motor drive device - Google Patents

Description

  The present invention relates to a synchronous motor drive device, and more particularly to a synchronous motor drive device with improved control characteristics.

  When drive control of a synchronous motor is performed, the motor current is generally controlled according to pulse width modulation (PWM) based on vector control. When operating with a reduced torque characteristic at a speed higher than the base speed, the voltage is constant and the phase of the voltage with respect to the field axis is controlled instead of the variable voltage control by PWM (see, for example, Patent Document 1). ).

JP 2010-124544 A (Overall)

  In the case of a configuration in which the output current of the drive device is controlled by phase control as disclosed in Patent Document 1, it is necessary to detect the rotational position of the synchronous motor, and a resolver is usually used. However, since the output of this resolver changes depending on the ambient temperature, for example, when the ambient temperature of the synchronous motor changes from the time of adjustment, a detection error may occur, resulting in a change in torque characteristics, and normal operation may not be possible. there were. As a countermeasure, it is conceivable to correct the position detection angle by detecting the temperature, but for that purpose, a temperature detector is required. The present invention has been made in view of the above problems, and an object of the present invention is to provide a drive device for a synchronous motor that can correct a temperature drift of a resolver output without providing a temperature detector.

To achieve the above object, a drive device for a synchronous motor according to the present invention includes an inverter that drives a synchronous motor having a resolver attached to a rotating shaft, and a first detection current that is an output current of the inverter. 1 current detector , a second current detector that detects a second detected current that is a field current of the synchronous motor, and an inverter control unit that controls the inverter, the inverter control unit, The calculation means for obtaining the load angle of the synchronous motor from the position detection angle of the resolver and the first and second detection currents, and the load angle is added to the position detection angle of the resolver with the first detection current. The conversion means for obtaining the torque current feedback of the synchronous motor by converting the value as the reference phase and the voltage current complement so that the difference between the torque current feedback and the torque current reference is minimized. Current control means for outputting a value; voltage phase calculation means for obtaining the output voltage phase of the inverter by adding the voltage phase compensation value, the position detection angle of the resolver, and the load angle; and the position detection angle of the lerva The position correction means corrects the integration of the current control means when the torque current of the synchronous motor is equal to or lower than a predetermined threshold value and the rotational speed of the synchronous motor is equal to or higher than the predetermined threshold value. The output of the amplifier is integrated and added to the position detection angle of the resolver.

  According to the present invention, it is possible to provide a drive device for a synchronous motor that can correct a temperature drift of a resolver output without providing a temperature detector.

1 is a circuit configuration diagram of a synchronous motor drive device according to Embodiment 1 of the present invention; FIG. 1 is an internal configuration diagram of a torque current amplifier of a synchronous motor drive device according to Embodiment 1 of the present invention. FIG. The internal block diagram of the temperature correction circuit of the drive device for synchronous motors which concerns on Example 1 of this invention. The internal block diagram of the temperature correction circuit of the drive device for synchronous motors which concerns on Example 2 of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  A synchronous motor drive device according to a first embodiment of the present invention will be described below with reference to FIGS.

  FIG. 1 is a circuit configuration diagram of a synchronous motor drive device according to Embodiment 1 of the present invention. An alternating current is fed from the alternating current power source 1 to the rectifier 2, converted into a direct current having a desired voltage, and supplied to the inverter 4 through the smoothing capacitor 3. The inverter 4 converts the direct current into an alternating voltage and drives the synchronous motor 5. The power device constituting the inverter 4 is on / off controlled by a gate signal supplied from the inverter control unit 10. A resolver 6 is attached to the rotating shaft of the synchronous motor 5, and this position detection angle is given to the inverter control unit 10. Further, a current detector 7 is provided on the output side of the inverter 4, and this output is also given to the inverter control unit 10 as current feedback Iu, Iv, Iw. Further, the field winding of the synchronous motor 5 is DC-excited by the excitation power supply 8, and the field current is detected by the current detector 9 and given to the inverter control unit 10.

  Next, the internal configuration of the inverter control unit 10 will be described.

  The difference between the speed reference ωr * and the speed feedback ωr given from the outside becomes an input to the speed controller 11. The speed feedback ωr is an output of the differentiator 21 that receives the corrected position detection angle θr as will be described later. The speed controller 62 performs adjustment control so that the deviation between the two is minimized, and outputs a torque reference T *. The torque reference T * is divided by the magnetic flux command φ * in the divider 12 to obtain the torque current reference IT *. This torque current reference IT * is compared with the torque current feedback IT, and the deviation between the two becomes an input to the current controller 13. The torque current feedback IT is an output of the three-phase-MT converter 19, and details thereof will be described later. The current controller 13 outputs the voltage phase compensation value Δθ * so as to minimize the deviation between the torque current reference IT * and the torque current feedback IT, and supplies the voltage phase calculator 14 with the voltage phase compensation value Δθ *. In the voltage phase calculator 14, the position detection angle θr that is the output of the mechanical angle / electrical angle converter 20, the load angle δ that is the output of the magnetic flux calculator 18, and the voltage phase compensation value Δθ * are added together. Obtain the voltage phase reference θ *. The voltage phase reference θ * is a command value for the output voltage phase of the inverter 4, and the relationship between these angles will be described later.

  When the voltage phase reference θ * and the voltage amplitude reference value V1 of the voltage to be output from the inverter 4 supplied from the outside are supplied to the polar coordinate three-phase converter 15, the polar coordinate three-phase converter 15 uses the input polar coordinate reference value. Conversion to three-phase voltage reference values Vu *, Vv *, Vw *. Then, the three-phase voltage reference values Vu *, Vv *, and Vw * are converted by the PWM converter 16 into the gate signal of the power device that constitutes the inverter 4 to drive the inverter 4.

  The three-phase current feedback of Iu, Iv, and Iw detected by the current detector 7 is given to the three-phase dq converter 17, where it is converted into two-axis current feedback Id and Iq. The conversion reference phase at this time is the corrected position detection angle θr. Here, the corrected position detection angle θr is obtained by correcting the detection position of the resolver 6 into the electrical angle by the mechanical angle / electrical angle converter 20 and correcting it by the position correction circuit 21 described later. The mechanical angle / electrical angle converter 20 obtains the detected mechanical angle by multiplying P / 2, where P is the number of poles of the synchronous motor 5. Since the corrected position detection angle θr indicates the position of the field winding that is the magnetic pole of the synchronous motor 5, the d-axis current feedback Id is the current of the field winding axis, and the q-axis current feedback Iq is orthogonal thereto. It becomes the current of the axis that performs.

  Here, the q-axis current feedback Iq is different from the torque current feedback IT. The torque current feedback IT is obtained by converting the three-phase current feedback Iu, Iv, Iw by the three-phase-MT converter 19. The conversion reference phase of the three-phase-MT converter 19 is a value obtained by adding the load angle δ to the magnetic pole position detection value θr. This load angle δ indicates the angle at which the main magnetic flux of the motor deviates from the field winding axis due to the armature reaction of the load currents Iu, Iv, Iw when the load currents Iu, Iv, Iw flow through the synchronous motor 5. Accordingly, the torque current feedback IT corresponding to the torque axis of the three-phase-MT converter 19 is orthogonal to the shifted main magnetic flux, and thus becomes the torque axis current when the actual synchronous motor 5 is controlled in two axes. The load angle δ is an angle proportional to the torque current feedback IT in a region where the torque current feedback IT is small, and is also referred to as an internal phase difference angle. This load angle δ can be obtained by applying the d-axis current feedback Id and the q-axis current feedback Iq and the field current If detected by the current detector 9 to the magnetic flux calculator 18. The magnetic flux calculator 18 calculates the gap magnetic flux from these currents and the constants of the synchronous motor 5, and further calculates the load angle δ from the dq axis gap magnetic flux. The field current If is the output of the excitation power supply 8, and the excitation power supply 8 is controlled by the output of the field current calculator 22 that receives the magnetic flux command φ *.

  Next, the configuration and operation of the position correction circuit 21 will be described below with reference to FIGS. FIG. 2 is an internal configuration diagram of the current controller 13. The current controller 13 is configured so that the sum of the difference between the torque current reference IT * and the torque current feedback IT amplified by the proportional amplifier 131 and the amplifier amplified by the integral amplifier 132 becomes the voltage phase compensation value Δθ *. A configured PI controller. Then, the output of the integrating amplifier 132 is used as the input of the position correction circuit 21.

  FIG. 3 is an internal configuration diagram of the position correction circuit 21. The output of the integrating amplifier 132 is given to the integrating circuit 217 via the switch circuit 216, and the output of the integrating circuit 217 becomes the position correction amount ΔθT. The closing condition of the switch circuit 216 is created with the following configuration. The torque current feedback IT is given to the a terminal of the comparison circuit 212 via the absolute value circuit 211. The minimum current setting value Imin is given to the b terminal of the comparison circuit 212. The comparison circuit 212 outputs a signal 1 to the AND circuit 213 when the absolute value of the current feedback IT is less than or equal to the minimum current set value Imin. Similarly, the speed feedback ωr is given to the a terminal of the comparison circuit 212 via the absolute value circuit 214. The maximum speed set value ωmax is given to the b terminal of the comparison circuit 212. The comparison circuit 215 outputs the signal 1 to the AND circuit 213 when the absolute value of the speed feedback ωr is greater than or equal to the maximum speed setting value ωmax. The AND circuit 213 closes the switch circuit 216 when both conditions are satisfied.

  As described above, the position correction circuit 21 outputs the position correction amount ΔθT when the rotational speed of the synchronous motor 5 is equal to or higher than a predetermined threshold and the load factor is equal to or lower than a predetermined value. If the synchronous motor 5 is in a no-load operation and the position detection angle θr, which is the output of the mechanical angle / electrical angle converter 20, is accurate, the position correction amount ΔθT should be zero. In this state, if the entire closed loop system is balanced with the position detection amount θr added to the position detection angle θr, it can be considered that the position detection angle θr has an error of the position correction amount ΔθT due to temperature drift or the like. It is a translation. Since this position correction amount ΔθT is integrated and held by the integration circuit 217, even if the output of the AND circuit 213 becomes 0 and the switch circuit 216 is opened, the value is held.

  In FIG. 1, a position detector mounting error correction amount ΔθP given from the outside is added to the output position correction amount ΔθT of the position correction circuit 21. This literally corrects an error when the resolver 6 is mounted. Yes, it always corrects the mounting error obtained by some method. According to the first embodiment, even if the position detector mounting error correction amount ΔθP includes an error, the position correction amount ΔθT is obtained by including the error and the above-described temperature drift error, so that the error is also corrected. It becomes possible. Further, the correction including the mounting error can be performed without giving the position detector mounting error correction amount ΔθP.

  Next, the sign of the position correction amount ΔθT will be considered. When a positional deviation due to temperature drift or the like occurs in the direction of decreasing the load angle δ, the positional correction amount ΔθT for correcting the positional deviation is a positive sign, and in the opposite case, a negative sign. The fact that the positional deviation occurs in the direction of decreasing the load angle δ means that the synchronous motor 5 is displaced in the reverse direction during forward rotation, and conversely, the positional deviation occurs in the direction of increasing the load angle δ. This means that the synchronous motor 5 is deviated in the normal rotation direction during the normal rotation.

  FIG. 4 is an internal configuration diagram of a temperature correction circuit 21A of the synchronous motor drive device according to the second embodiment of the present invention. In the second embodiment, the same parts as those in the internal configuration diagram of the position correction circuit 21 of the synchronous motor drive device according to the first embodiment of the present invention shown in FIG. The second embodiment is different from the first embodiment in that a reduction characteristic circuit 218 having a torque current feedback IT as an input is provided, and the output and the output of the integration circuit 217 are multiplied by a multiplier 219 to thereby obtain a position correction amount ΔθT. It is a point that I tried to get.

  Under the condition that the synchronous motor 5 is operated at a predetermined speed or more, the iron loss and mechanical loss of the synchronous motor 5 are inevitably generated, so that the torque current feedback IT does not become zero. If the torque current feedback IT is not 0, the output of the integrating amplifier 132 is always generated. Therefore, the position correction amount ΔθT of the output of the integrator 217 in FIG. 3 is considered to be overcorrected accordingly. . Therefore, this overcorrection is absorbed by the reduction characteristic circuit 218 of FIG. The reduction characteristic circuit 218 may perform a calculation that is inversely proportional to the torque current feedback IT, but may be obtained by referring to a table based on actual measurement data or the like.

  Although several embodiments have been described above, these embodiments are presented as examples, and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  For example, phase control by the voltage phase calculator 14 shown in FIG. 1 may be performed when the synchronous motor 5 is equal to or higher than a predetermined speed, and may be switched to normal two-axis vector control when the speed is lower than the predetermined speed. . In this case, the field weakening control is generally performed to weaken the magnetic flux command φ * in proportion to the speed at a predetermined speed or higher.

  Further, the speed controller 11 of FIG. 1 is not necessarily required, and the torque control may be performed by directly applying the torque current reference IT to the current controller 13.

  Alternatively, the output of the field current calculator 22 and the field current If may be matched to perform closed loop control, and further, field current control may be performed so that the reactive current of the synchronous motor 5 becomes a predetermined value. good.

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Rectifier 3 Smoothing capacitor 4 Inverter 5 Synchronous motor 6 Resolver 7 Excitation power supply 8, 9 Current detector 10 Inverter control part 11 Speed controller 12 Divider 13 Current controller 14 Voltage phase calculator 15 Polar coordinate three-phase conversion 16 PWM controller 17 3-phase dq converter 18 Magnetic flux calculator 19 3-phase-MT converter 20 Mechanical angle / electrical angle converter 21, 21A Position correction circuit 22 Field current calculator 131 Proportional amplifier 132 Integrating amplifier 211, 214 Absolute value circuit 212, 215 Comparison circuit 213 AND circuit 216 Switch circuit 217 Integration circuit 218 Reduction characteristic circuit 219 Multiplier

Claims (4)

An inverter that drives a synchronous motor having a resolver attached to a rotating shaft;
A first current detector that detects a first detection current that is an output current of the inverter;
A second current detector for detecting a second detection current which is a field current of the synchronous motor;
An inverter control unit for controlling the inverter;
The inverter control unit
Calculating means for obtaining a load angle of the synchronous motor from the position detection angle of the resolver and the first and second detection currents;
Conversion means for converting the first detection current as a reference phase using a value obtained by adding the load angle to the position detection angle of the resolver to obtain torque current feedback of the synchronous motor;
Current control means for comparing the torque current feedback and the torque current reference and outputting a voltage phase compensation value so that the difference is minimized;
Voltage phase calculation means for obtaining the output voltage phase of the inverter by adding the voltage phase compensation value, the position detection angle of the resolver, and the load angle;
Position correction means for correcting the position detection angle of the resolver,
The position correcting means includes
When the torque current of the synchronous motor is equal to or less than a predetermined threshold and the rotational speed of the synchronous motor is equal to or higher than the predetermined threshold, the output of the integrating amplifier of the current control means is integrated and added to the position detection angle of the resolver. A drive device for a synchronous motor, characterized in that
The torque current reference is
It is an output of speed control means for comparing the speed feedback of the synchronous motor obtained from the position detection angle of the resolver and a given speed command and controlling so that the difference is minimized. The synchronous motor drive device according to claim 1. The position correcting means includes
The synchronous motor drive device according to claim 1, further comprising a correction unit that reduces the output in response to an increase in the torque feedback current value.   4. The drive device for a synchronous motor according to claim 1, wherein normal two-axis vector control is performed when the rotational speed of the synchronous motor is equal to or lower than a base speed. 5.