JP6590602B2 - Motor drive device, air conditioner and program - Google Patents

Description

  The present invention relates to a motor drive device, an air conditioner, and a program.

As a background art of this technical field, the abstract of the following Patent Document 1 states that “when the output voltage value of the power converter is saturated, the deviation of the q-axis voltage command value and the current detection causes the control reference axis and the motor to By calculating the phase error command value, which is the deviation from the reference axis, and correcting the output voltage command value of the power converter using this phase error command value, highly accurate and highly responsive torque control is achieved. Realize ".
Further, the abstract of Patent Document 2 states that “the difference (axis error) between the position of the magnetic flux axis of the AC synchronous motor and the position of the magnetic flux axis assumed in the controller is calculated, and this is made zero. Sensorless driving is realized by correcting the rotational speed, and further, means for extracting a pulsating component of torque generated by the electric motor or load device based on the calculated value of the shaft error, and means for compensating for it are provided. Can be achieved. "
Non-Patent Document 1 describes a technique for enlarging a high-speed rotation region using field-weakening control.

JP 2007-252052 JP JP 2005-198402 JP

Hatsuse, Notohara, Oi, Tamura, Uyoko, Funayama, “Examination of application of voltage phase control type field weakening control to room air conditioner”, 2009 IEEJ Industrial Application Conference Proceedings, The Institute of Electrical Engineers of Japan

By the way, it is conceivable to switch the field-weakening control disclosed in Patent Literature 1 and Non-Patent Literature 1 and the control for compensating the torque pulsation component disclosed in Patent Literature 2 in accordance with the rotational speed and load torque of the motor. . However, simply switching between the two controls has a problem that abnormal noise, vibration, and the like are generated by a shock in which the motor current and the rotational speed suddenly change.
The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a motor drive device, an air conditioner, and a program that can suppress abnormal noise, vibration, and the like.

  In order to solve the above problems, a motor driving device of the present invention includes a power conversion circuit that converts a DC voltage into an AC voltage and applies it to a motor that drives a load device that generates a load torque that varies periodically. A torque fluctuation compensation amount output section that outputs a torque fluctuation compensation amount that fluctuates in response to a periodic fluctuation of the load torque, and a motor output torque that is output by the motor is varied based on the torque fluctuation compensation amount. A speed fluctuation suppressing unit that suppresses the rotational speed fluctuation of the motor, a function of designating one of the first operation mode and the second operation mode, and the torque fluctuation before switching the operation mode. In the operation mode designating unit having a function of suppressing the fluctuation amplitude of the compensation amount, and in the first operation mode, the modulation factor in the power conversion circuit is set to A modulation rate setting unit having a function of suppressing the modulation rate below a value and a function of suppressing the modulation rate below a second predetermined value different from the first predetermined value in the second operation mode. It is characterized by that.

  According to the motor drive device, the air conditioner, and the program of the present invention, it is possible to suppress abnormal noise and vibration.

1 is a block diagram of a motor drive system according to a first embodiment of the present invention. It is a block diagram of a controller. It is a block diagram of a speed fluctuation suppression control unit. (A) Waveform diagram, such as motor output torque, (b) Other waveform diagrams, such as motor output torque. (A) Waveform diagram of modulation rate, (b) Another waveform diagram of modulation rate. It is a waveform diagram of the modulation factor and voltage phase. It is a vector diagram which shows a voltage vector. It is a block diagram of a correction phase calculation unit. It is a wave form diagram of a rotational speed detection value, a modulation factor, and a voltage phase in 1st Embodiment. It is a diagram showing another voltage vector. It is a flowchart (1/2) of the control program of a 1st embodiment. It is a flowchart (2/2) of the control program of 1st Embodiment. It is a wave form diagram of a rotational speed detection value, a modulation factor, and a voltage phase in 2nd Embodiment. It is a wave form diagram of a rotational speed detection value, a modulation factor, and a voltage phase in the third embodiment. It is a front view of the air conditioner by 4th Embodiment.

[First Embodiment]
<Outline of Embodiment>
Permanent magnet type synchronous motors (hereinafter referred to as “motors”) have higher efficiency than induction motors, and thus have a wide range of applications from home appliances to industrial equipment or electric vehicles. In addition, these devices are required to increase the efficiency of the low-speed rotation range (light load) with the movement of global warming prevention and energy saving, and at high speed rotation to improve the usability (comfort) of the device. Expansion of the drive range in the region (high load) is also required.

  For example, in the case of home air conditioners, improvement of APF (Annual Performance Factor), which is an energy saving index, and low temperature heating capacity (heating capacity at an outside temperature of 2 ° C), which is an index of high output ) Improvement is required. In particular, as a means for improving the efficiency in the low-speed rotation range, it is conceivable to design the motor so as to be optimized in the low-speed rotation range by increasing the magnet amount and the winding. However, if the motor design is optimized in the low-speed rotation region, the induced voltage generated in the high-speed rotation region increases, so that the drivable region becomes narrow and the efficiency in the high-speed rotation region may be reduced.

  Therefore, in the present embodiment, field weakening control is applied in order to expand the high-speed rotation range of the motor optimized in the low-speed rotation range. Further, since the pulsation of the load torque becomes large in the low speed rotation region, the control for compensating the pulsation of the load torque is performed. And this embodiment suppresses that a motor current and a rotational speed fluctuate rapidly when switching control of a high-speed rotation area and a low-speed rotation area, and tries to suppress abnormal noise or vibration at the time of switching. It is.

<Overall Configuration of Embodiment>
Next, the overall configuration of the motor drive system 100 according to the present embodiment will be described with reference to the block diagram shown in FIG. The motor drive system 100 includes a motor drive device 110 and a machine unit 120. The machine unit 120 includes a motor 36 that is a permanent magnet type three-phase synchronous motor, and a load device 38 (for example, a compression mechanism that compresses refrigerant) driven by the motor 36.

  The motor driving device 110 is a DC power source 35 that outputs a DC voltage Ed, and an inverter that generates a three-phase AC voltage by PWM modulation (Pulse Width Modulation) and supplies the DC voltage Ed to the motor 36. A power conversion circuit 34, a current detection circuit 32 that detects a current flowing through the motor 36, and a controller 30 are included. The controller 30 receives the current detection value from the current detection circuit 32 and outputs a drive signal for driving the power conversion circuit 34 by the PWM calculation unit 6 provided therein.

<Configuration of controller 30>
Next, the detailed configuration of the controller 30 will be described with reference to the block diagram shown in FIG.
The controller 30 includes hardware as a general computer such as a CPU (Central Processing Unit), a DSP (Digital Signal Processor), a RAM (Random Access Memory), and a ROM (Read Only Memory). A control program executed by the CPU, a microprogram executed by the DSP, various data, and the like are stored. In FIG. 2, the inside of the controller 30 shows the functions realized by the control program and the microprogram as blocks.

  Before describing each part of the controller 30, the coordinate axes will be described. In the following description, the main magnetic flux direction of the permanent magnet provided on the rotor of the motor 36 is defined as the d axis, and the axis that is electrically advanced 90 degrees (electrical angle 90 degrees) in the rotational direction from the d axis is defined as the q axis. Both may be referred to as the dq axis. The dq axis is a rotating coordinate system.

式（１）において、Ｋｅは誘起電圧定数、Ｌｄはｄ軸インダクタンス、Ｌｑはｑ軸インダクタンス、Ｉｑｃはｑ軸電流検出値である。 (D-axis current command calculation unit 1)
In FIG. 2, the d-axis current command calculation unit 1 generates a d-axis current command Id * for the motor 36. If the motor 36 is a non-salient pole type motor, the d-axis current command Id * is zero in the normal region (region where field weakening control is not performed). When the motor 36 is a salient pole type motor, for example, the d-axis current command Id * may be output using a general formula that maximizes the torque / current ratio shown in the following formula (1).

In Equation (1), Ke is an induced voltage constant, Ld is a d-axis inductance, Lq is a q-axis inductance, and Iqc is a q-axis current detection value.

(Three-phase / dq converter 10)
The three-phase / dq conversion unit 10 converts the current detection values Iu, Iv, and Iw output from the current detection circuit 32 (see FIG. 2) into the d-axis and q-axis current detection values Idc and Iqc of the dq coordinate system that is the rotation coordinates. Convert.

(Current command calculation unit 2)
The current command calculation unit 2 performs proportional integral control based on the deviation between the d-axis current command Id * and the d-axis current detection value Idc and the deviation between the q-axis current command Iq * and the q-axis current detection value Iqc. The d-axis and q-axis corrected current commands Id ** and Iq ** are output so that the deviations “Id * −Idc” and “Iq * −Iqc” approach zero values.

式（２）において、Ｒは巻線抵抗値、ω*は回転速度指令である。 (Voltage calculation unit 3)
Based on the d-axis and q-axis corrected current commands Id ** and Iq ** described above and the motor voltage equation (differential term omitted) shown in the following equation (2), the voltage calculation unit 3 The shaft motor voltage commands Vd * and Vq * are calculated.

In Equation (2), R is a winding resistance value and ω * is a rotational speed command.

(Voltage correction calculation unit 4)
Based on the d-axis and q-axis motor voltage commands Vd * and Vq * and the correction phase value ΔθV _weak , the voltage correction calculation unit 4 performs the d-axis and q-axis corrected motor voltage commands Vd ** and Vq **. Is calculated. More specifically, the motor voltage amplitude value and the basic voltage phase θV _base are calculated from the d-axis and q-axis motor voltage commands Vd * and Vq *, and the sum of the basic voltage phase θV _base and the correction phase value ΔθV _weak is calculated. D-axis and q-axis corrected motor voltage commands Vd ** and Vq ** are calculated with a voltage phase θV. By this calculation, if the correction phase value ΔθV _weak is a positive value, the voltage phase θV advances from the basic voltage phase θV _base and the field weakening control state is entered.

(Dq / 3-phase converter 5)
The dq / 3-phase conversion unit 5 converts the d-axis and q-axis corrected motor voltage commands Vd ** and Vq ** in the dq coordinate system, which are rotational coordinates, into the three-phase AC voltage commands Vu *, Vv *, Convert to Vw *.

(Dq / 3-phase converter 6)
The PWM calculation unit 6 converts the three-phase AC voltage commands Vu *, Vv *, Vw * into drive signals that are PWM signals. Specifically, the three-phase AC voltage commands Vu *, Vv *, Vw * are compared with the triangular wave carrier signal, and a drive signal is generated based on the comparison result. The generated drive signal is supplied to the power conversion circuit 34 (see FIG. 1) as described above.

(Speed control unit 7)
The speed control unit 7 uses a proportional integral control based on the deviation between the rotational speed command ω * supplied from the host control system and the rotational speed detection value ω so that the deviation becomes small. Command Iq * _asr is calculated.

(Speed fluctuation suppression control unit 8)
The speed fluctuation suppression control unit 8 estimates the pulsating torque component ΔTm based on the detected rotational speed value ω and the shaft error calculation value Δθ, and uses integral control so that the pulsating torque component ΔTm approaches a zero value. Speed fluctuation suppression current command Iqsin * is calculated. Here, the axis error calculation value Δθ is the difference between the estimated value of the electrical angle of the rotor of the motor 36 and the actual electrical angle. The pulsating torque component ΔTm is the difference between the motor output torque and the load torque.

Here, the details of the speed fluctuation suppression control unit 8 will be described with reference to the block diagram shown in FIG.
In FIG. 3, the speed fluctuation suppression control unit 8 includes a pulsation torque estimation unit 80, a Fourier transformer 81, an integration controller 82, a Fourier inverse transformer 83, an amplitude limiter unit 84, and a cosine / sine calculation unit 85. And have. The pulsation torque estimation unit 80 generates a pulsation torque component ΔTm (= 2 · Δθ ·) based on the rotation speed detection value ω, the moment of inertia J of the motor 36, the number of poles P of the motor 36, and the axis error calculation value Δθ. J · ω ² / P) is output. The principle is disclosed in Patent Document 2 (paragraphs 0034 to 0039) described above.

  Also, the cosine / sine calculation unit 85 multiplies the rotational speed detection value ω by “2 / P” (P is the number of poles) to obtain the mechanical speed ωr, and integrates the mechanical speed ωr to obtain the mechanical angular position θr. The mechanical angle sine component sin θr and the mechanical angle cosine component cos θr are output. The Fourier transformer 81 calculates the multiplication results obtained by multiplying the pulsating torque component ΔTm by −sin θr and −cos θr, respectively, and attenuates the component of the calculation result equal to or higher than the mechanical speed ωr by the low-pass filter. That is, the pulsation torque component ΔTm is coordinate-transformed into a coordinate system that rotates at the machine speed ωr, and the sine component and cosine component of the pulsation torque component ΔTm are output from the Fourier transformer 81.

  The integration controller 82 subtracts the sine component and cosine component of the pulsating torque component ΔTm from each target value (zero value), and integrates each obtained subtraction result by an integral gain Ki. These integration results become a sine component and a cosine component of the speed variation suppression current value for suppressing the speed variation due to the pulsating torque component ΔTm. The inverse Fourier transformer 83 multiplies the sine component of the speed fluctuation suppression current value by −sin θr, multiplies the cosine component by −cos θr, adds the multiplication results, and multiplies the signal by “2”. Output as a speed fluctuation suppression current value.

  The amplitude limiter 84 limits the amplitude of the speed fluctuation suppression current value output from the Fourier inverse transformer 83 as necessary, and outputs the result as a speed fluctuation suppression current command Iqsin *. The amplitude limit value is referred to as an amplitude limit value WI. When the amplitude limitation is not performed, the amplitude limitation value WI is set to the maximum value WImax. The maximum value WImax is set to such a value that the amplitude of the speed fluctuation suppression current value does not reach practically. In this case, the speed fluctuation suppression current value output from the Fourier inverse transformer 83 is output as it is as the speed fluctuation suppression current command Iqsin *. On the other hand, when the amplitude limit value WI becomes less than the maximum value WImax, the result of amplitude limiting the speed fluctuation suppression current value by the amplitude limit value WI is output as the speed fluctuation suppression current command Iqsin *.

(Outline of control)
Here, an outline of the control of the controller 30 will be described before describing another configuration of the controller 30.
First, the reason why the speed fluctuation is suppressed by the speed fluctuation suppression current command Iqsin * will be described.
FIG. 4A shows waveforms at one rotation of the mechanical angle of the load torque τL (broken line) and the motor output torque τm (solid line) when the speed fluctuation is not “suppressed”. Here, the load torque τL assumes a case where a single rotary compression mechanism or a reciprocating compression mechanism is applied as the load device 38 (see FIG. 1). In this type of compression mechanism, as shown in the drawing, the load torque τL varies according to the rotational angle position during one rotation of the mechanical angle.

  As shown in FIG. 4A, when the motor output torque τm is constant, the machine speed ωr varies depending on the difference between the motor output torque τm and the load torque τL. When the machine speed ωr varies, vibration and noise of the motor 36 and the load device 38 increase. Furthermore, when the fluctuation of the machine speed ωr is excessive, a situation may occur in which the motor 36 stops.

  On the other hand, FIG. 4B is a waveform diagram when the motor output torque τm is controlled to match the load torque τL. When the load torque τL and the motor output torque τm coincide, the machine speed ωr becomes a constant value as shown in the figure, and vibration and noise can be suppressed. However, in order to make the motor output torque τm coincide with the load torque τL, the q-axis current command Iq * pulsates according to the load torque τL as shown in the figure, and the q-axis voltage Vq also pulsates.

式（３）において、Ｅｄは直流電源３５（図１参照）が出力する直流電圧値である。また、Ｖ１は、モータ印加電圧Ｖｕ，Ｖｖ，Ｖｗの基本波の波高値である。 However, when the control for suppressing the speed fluctuation is performed, another problem may occur.
Therefore, the problem in the case where the control for suppressing the speed fluctuation is performed will be described with reference to the waveform diagrams shown in FIGS. FIG. 5A shows the waveform of the q-axis voltage Vq shown in FIG. 4B as the modulation factor kh. Here, the modulation factor kh is expressed by the following equation (3).

In Expression (3), Ed is a DC voltage value output from the DC power supply 35 (see FIG. 1). V1 is the peak value of the fundamental wave of the motor applied voltages Vu, Vv, Vw.

  The modulation rate kh has a modulation rate limit value khmax, which is the maximum value that can be realized. This is because the instantaneous value of the motor applied voltage exceeds the DC voltage Ed because the motor applied voltages Vu, Vv, and Vw are generated by PWM modulation of the DC voltage Ed by the power conversion circuit 34 (see FIG. 1). It is because it is not possible. If the motor applied voltage is a sine wave, the modulation factor limit value khmax is “1.0”. However, the modulation factor limit value khmax can be set to “1.15” by injecting the third harmonic. If the modulation rate kh is “1.15” or less, the motor applied voltage can be changed linearly with respect to the modulation rate kh. Therefore, a region of modulation factor kh that is “1.15” or less is referred to as a “linear region”.

  Furthermore, the modulation factor limit value khmax can be increased to “1.25” by injecting fifth or higher harmonics into the motor applied voltage and making the voltage waveform trapezoidal. However, when the modulation rate kh exceeds “1.15”, the relationship between the modulation rate kh and the motor applied voltage becomes nonlinear, for example, the motor applied voltage changes suddenly due to a slight change in the modulation rate kh. Therefore, a region having a modulation factor kh exceeding “1.15” is referred to as an “overmodulation region”.

  In FIG. 5A, the fluctuation range of the load torque τL is small, and the modulation factor kh exceeds the modulation factor limit value khmax (here, the maximum value “1.15” in the linear region) that can be linearly output. It is a wave form diagram when there is not. On the other hand, FIG. 5B shows a case where the fluctuation range of the compressor load torque increases and the modulation rate command kh * (ideal modulation rate) indicated by the broken line exceeds the modulation rate limit value khmax in the period T1. Is shown. In the period T1, the actual modulation rate kh is limited to the modulation rate limit value khmax as indicated by the solid line, and therefore a desired voltage cannot be applied to the motor 36. Thereby, the effect of the speed fluctuation suppression control is reduced, and there is a possibility that vibration and noise increase. For this reason, when a state such as that shown in FIG.

Therefore, referring to FIG. 6, one method for eliminating the state shown in FIG. 5B will be described.
FIG. 6 is a diagram showing an example of the modulation rate kh and the waveform of the voltage phase θV of the d-axis and q-axis corrected motor voltage commands Vd ** and Vq **, and the modulation rate limit value khmax is indicated by a broken line. The section TA in FIG. 6 is in the same state as in FIG. 5B, and since the vicinity of the peak of the modulation rate command kh * exceeds the modulation rate limit value khmax, the actual modulation rate kh is near the peak. It becomes a waveform that is cut off. As a result, the peak values of the motor applied voltages Vu, Vv, Vw are suppressed, and linear control cannot be performed.

Therefore, as shown in the section TB, field weakening control may be performed to advance the voltage phase θV by the correction phase value ΔθV _weak so that the peak value of the modulation rate command kh * does not exceed the modulation rate limit value khmax.
FIG. 7 shows a vector diagram in the dq coordinate system corresponding to FIG.
In FIG. 7, the voltage vector VA corresponds to the section TA, and the voltage vector VB corresponds to the section TB.

As described above, if the modulation factor kh is “1.15” or less, the field-weakening control and the speed fluctuation suppression control can be performed together. However, in this method, the correction phase value ΔθV _weak becomes large in the high-speed rotation region of the motor 36, and the d-axis current increases. For this reason, in the high-speed rotation region, it is desirable to switch the control state so that the motor 36 is driven in the overmodulation region (that is, overmodulation field weakening control is performed).

  In switching the control state, it is also possible to execute overmodulation field weakening control after temporarily stopping the speed fluctuation suppression control. However, once the speed fluctuation suppression control is stopped, torque fluctuation and rotational speed fluctuation occur at that time, causing a problem that vibration and noise increase. Therefore, in the present embodiment, in the speed fluctuation suppression control, the amplitude of the modulation factor kh is gradually reduced, and after the amplitude of the modulation factor kh becomes zero, switching to overmodulation field weakening control is performed.

(Control switching command section 9)
Returning to FIG. 2, the control switching command unit 9 outputs control signals such as the mode designation signal MD and the amplitude limit value WI based on the modulation rate command kh * and the rotation speed detection value ω. As described above, the amplitude limit value WI is the limit value of the amplitude of the speed fluctuation suppression current command Iqsin *, and is supplied to the amplitude limiter unit 84 (see FIG. 3). The mode designation signal MD is a signal that designates one of the following operation modes.
Speed fluctuation suppression mode (first operation mode): This operation mode is a mode for realizing the speed fluctuation suppression control described above.
Overmodulation field weakening mode (second operation mode): This operation mode is a mode for realizing the above-described overmodulation field weakening control.

(Modulation rate setting unit 14)
The modulation rate setting unit 14 outputs the modulation rate limit value khmax based on the mode designation signal MD supplied from the control switching command unit 9. That is, the modulation rate setting unit 14 sets the modulation rate limit value khmax to the predetermined value kh1 = 1.15 in the speed fluctuation suppression mode, and sets the modulation rate limit value khmax to the predetermined value in the overmodulation field weakening mode. Set kh2 = 1.25. When the mode designation signal MD is changed, the modulation factor limit value khmax is set to gradually change from the predetermined value kh1 to the predetermined value kh2 or from the predetermined value kh2 to the predetermined value kh1.

(Correction phase calculator 13)
The correction phase calculator 13 outputs the correction phase value ΔθV _weak based on the modulation rate limit value khmax output from the modulation rate setting unit 14 and the modulation rate command kh *.
Here, the configuration of the correction phase calculator 13 will be described with reference to the block diagram shown in FIG.
In FIG. 8, when a positive peak value appears in the modulation factor command kh *, the peak hold unit 131 latches and outputs the peak value. The subtractor 132 subtracts the modulation factor limit value khmax from this peak value. Here, assuming that the output signal of the subtractor 132 is a positive value, the actual modulation rate kh has a waveform in which the vicinity of the peak is cut as shown in FIG.

The integrator 133 multiplies the output signal of the subtracter 132 by an integration constant Kv and integrates it. The phase output unit 134 outputs a corrected phase value ΔθV _weak corresponding to the integration result of the integrator 133. That is, if the integration result is a negative value, the correction phase value ΔθV _weak becomes a zero value, and if the integration result is a positive value, the correction phase value ΔθV _weak becomes a value that monotonously increases with respect to the integration result.

As described above, when the correction phase value ΔθV _weak is supplied to the voltage correction calculation unit 4, the voltage correction calculation unit 4 corrects the voltage phase θV of the d-axis and q-axis motor voltage commands Vd * and Vq *. The d-axis and q-axis corrected motor voltage commands Vd ** and Vq ** advanced by the value ΔθV _weak are output. As a result, the peak value of the modulation factor kh approaches the modulation factor limit value khmax and eventually coincides.

(DC voltage detector 16)
Returning to FIG. 2, the DC voltage detection unit 16 detects the DC voltage Ed output from the DC power supply 35 (see FIG. 1), and outputs the result as a DC voltage detection value Edc.
(Modulation rate calculator 12)
The modulation factor calculator 12 calculates a modulation factor command kh * based on the detected DC voltage value Edc and the d-axis and q-axis motor voltage commands Vd * and Vq * output from the voltage calculator 3.

(Axis error calculator 11)
Based on the d-axis and q-axis corrected motor voltage commands Vd ** and Vq **, the d-axis and q-axis current detection values Idc and Iqc, and the rotational speed command ω *, the axis error calculation unit 11 4), the estimated value of the electrical angle of the rotor of the motor 36 (estimated angular position θd to be described later) and the axis error calculation value Δθ, which is the difference between the actual electrical angle, are output.

(PLL phase calculation unit 15, integrator 17)
In addition, the PLL phase calculation unit 15 outputs the rotation speed detection value ω using proportional integral control so that the axis error calculation value Δθ approaches a zero value. Further, the integrator 17 outputs the estimated angular position θd by integrating the rotational speed detection value ω.
As described above, the estimated angular position θd can be obtained by the axis error calculation unit 11, the PLL phase calculation unit 15, and the integrator 17 in order to realize the position sensorless control of the motor 36.

<Operation of Embodiment>
(Overview of operation)
Next, the outline of the operation of this embodiment will be described with reference to the waveform diagrams shown in FIGS.
FIGS. 9A to 9C are waveform diagrams of the rotational speed detection value ω, the modulation factor kh, and the voltage phase θV, respectively. In either case, the horizontal axis indicates time, but the time advances from left to right during acceleration and from right to left during deceleration.

  First, the outline of the operation at the time of acceleration of the rotational speed detection value ω will be described. 9A to 9C, in the section TD from time t0 to t1, the rotational speed detection value ω is constant, the modulation factor kh varies according to the pulsation torque component ΔTm, and the motor output torque τm Is controlled to be substantially equal to the load torque τL.

  In the section TD, the speed fluctuation suppression mode is selected as the operation mode, and the modulation factor limit value khmax is set to a predetermined value kh1 (= 1.15). In the section TD, the voltage phase θV is a positive value slightly higher than the zero value, and field weakening control is applied. That is, in the section TD, the speed fluctuation suppression control and the field weakening control are combined.

  In addition, in the section TE from time t1 to time t3, the rotational speed detection value ω increases with time. As a result, the average modulation rate khave, which is the average value of the modulation rate kh, also increases with time. Here, as shown in FIG. 9B, in this embodiment, the fluctuation amplitude of the modulation rate kh is reduced with the passage of time.

  At time t2, the fluctuation amplitude of the modulation factor kh becomes zero, and at that time, the speed fluctuation suppression current command Iqsin * is set to zero. That is, the speed fluctuation suppression control is stopped. As a result, as shown in FIG. 9C, the voltage phase θV slightly decreases at time t2. Further, the rotational speed detection value ω increases after time t2, and the average modulation factor khave reaches a predetermined value kh1 (= 1.15) at time t3. As a result, the operation mode is switched to the overmodulation field weakening mode, and the modulation factor limit value khmax is increased to a predetermined value kh2 (= 1.25). Also in the section TF after time t3, the rotational speed detection value ω continues to rise, and the voltage phase θV also increases with it.

  In the vector diagram shown in FIG. 10, voltage vectors in the dq coordinate system corresponding to the above-described sections TD, TE, and TF are shown as VD, VE, and VF. In FIG. 10, the voltage vector VE has the same amplitude as the voltage vector VD, and its voltage phase θVE is ahead of the voltage phase θVD of the voltage vector VD. Further, the voltage vector VF has a larger amplitude than the voltage vector VE, and the voltage phase θVF is further advanced.

  As described above, by gradually reducing (acceleration) or gradually increasing (deceleration) the fluctuation amplitude of the modulation factor kh in the speed fluctuation suppression mode, the speed fluctuation suppression mode, the overmodulation field weakening mode, Can be stably realized.

(Details of operation)
A flowchart of a control program executed in the controller 30 is shown in FIGS.
In FIG. 11, when the process proceeds to step S2, it is determined whether the current operation mode is the speed fluctuation suppression mode or the overmodulation field weakening mode. If the operation mode is the speed fluctuation suppression mode, the process proceeds to step S4, and the control switching command unit 9 (see FIG. 3) acquires the rotational speed detection value ω and the average modulation rate command khave * at that time. . The average modulation rate command khave * is a moving average value of the modulation rate command kh *. Unless the modulation rate command kh * exceeds the modulation rate limit value khmax, the average modulation rate shown in FIG. Same as khave.

  Next, when the process proceeds to step S6, the control switching command unit 9 determines the acceleration / deceleration state based on the detected rotational speed value ω acquired multiple times in the past. Here, if it is determined that the speed is “constant speed” that is neither accelerated nor decelerated, the process returns to step S2. On the other hand, if it is determined that the vehicle is accelerating, the process proceeds to step S8.

  In step S8, the control switching command unit 9 determines whether or not the rotational speed detection value ω is equal to or higher than a predetermined limit start speed ωth. This is because the field-weakening control is not applied when the rotation speed detection value ω is in the low-speed rotation range. If the rotation speed detection value ω is a low speed rotation region less than the limit start speed ωth, it is determined as “No”, and the process proceeds to step S12.

  In step S12, the control switching command unit 9 determines whether or not the amplitude limit value WI is a zero value. If the rotation speed detection value ω is in the low speed rotation range, the amplitude limit value WI is the maximum value WImax, so it is determined “No”, and the process proceeds to step S16. In step S16, the control switching command unit 9 determines whether or not the average modulation rate command khave * has reached a predetermined value kh1 (= 1.15). If the rotation speed detection value ω is in the low speed rotation range, the average modulation rate command khave * is lower than the predetermined value kh1, so it is determined “No”, and the process returns to step S2.

  As described above, if the vehicle is accelerating in the low speed rotation region, the loop of steps S2, S4, S6, S8, S12, and S16 is repeated. Thereafter, when the detected rotational speed value ω becomes equal to or higher than the limit start speed ωth, “Yes” is determined in step S8, and the process proceeds to step S10. In step S10, the control switching command unit 9 decreases the amplitude limit value WI by a predetermined value. Since the process of step S10 is repeatedly executed as long as acceleration is being performed, the amplitude limit value WI gradually decreases with the passage of time.

  In the period in which the amplitude limit value WI gradually decreases, as shown in the section TE in FIG. 9B, the fluctuation amplitude of the modulation factor kh also gradually decreases. When the amplitude limit value WI eventually becomes zero, “Yes” is determined in step S12, and the process proceeds to step S14. In step S14, the speed change suppression control is stopped by the control switching command unit 9. That is, the speed fluctuation suppression current command Iqsin * is set to zero.

  As the rotational speed detection value ω further increases, the average modulation rate command khave * eventually reaches a predetermined value kh1. In this case, “Yes” is determined in step S16, and the process proceeds to step S18. Here, in the control switching command unit 9, the amplitude limit value WI is set to a zero value, and the operation mode is switched to the overmodulation field weakening mode.

  However, the timing at which the operation mode is actually switched to the overmodulation field weakening mode is the timing at which the modulation rate command kh * first reaches the average modulation rate command khave * after step S18 is executed (or the modulation rate kh is The timing at which the average modulation rate khave is reached). This is to minimize the shock caused by switching the operation mode. When the operation mode is switched to the overmodulation field weakening mode, the modulation factor setting unit 14 gradually increases the modulation factor limit value khmax so as to become the predetermined value kh2 (= 1.25). The processing in the overmodulation field weakening mode will be described later.

Next, processing when the vehicle is decelerating in the speed fluctuation suppression mode will be described.
If it is determined in step S6 that the acceleration / deceleration state is “decelerating”, the process proceeds to step S20 in FIG. Here, the control switching command unit 9 determines whether the amplitude limit value WI is less than the maximum value WImax. If "Yes" is determined here, the process proceeds to step S22, and the amplitude limit value WI is increased by a predetermined value by the control switching command unit 9. If the amplitude limit value WI is equal to the maximum value WImax, step S22 is skipped.

  Next, when the process proceeds to step S24, the control switching command unit 9 determines whether or not the average modulation rate command khave * is equal to or less than a predetermined modulation rate khx. The predetermined modulation rate khx is set to a sufficiently low value that the amplitude limit value WI can be immediately set to the maximum value WImax. If "Yes" is determined here, the process proceeds to step S26, and the amplitude limit value WI is set to the maximum value WImax by the control switching command unit 9. If the average modulation rate khave exceeds the predetermined modulation rate khx, “No” is determined in step S24, and step S26 is skipped. Thus, when the processing of steps S20 to S26 is completed, the processing returns to step S2.

  Since the determination in step S20 is repeatedly executed as long as the acceleration / deceleration state is decelerating, step S22 is also repeatedly executed as long as the amplitude limit value WI is less than the maximum value WImax. As a result, the amplitude limit value WI eventually reaches the maximum value WImax. When the average modulation rate command khave * becomes equal to or less than the predetermined modulation rate khx, the amplitude limit value WI is immediately set to the maximum value WImax in step S26. Thus, during deceleration, the amplitude limit value WI reaches the maximum value WImax relatively quickly, and the vibration of the motor 36 is suppressed by the speed fluctuation suppression current command Iqsin *.

Next, processing in the overmodulation field weakening mode will be described.
If it is determined in step S2 that the operation mode is the overmodulation field weakening mode, the process proceeds to step S30 in FIG. 12, and an average modulation rate command khave * is acquired. Next, when the process proceeds to step S32, it is determined whether or not the average modulation rate command khave * is equal to or less than a predetermined value kh1 (= 1.15). If "Yes" is determined here, the process proceeds to step S34, and the operation mode is switched to the speed fluctuation suppression mode by the control switching command unit 9.

  However, the timing for switching the operation mode is the timing when the modulation rate command kh * first reaches the average modulation rate command khave * after step S34 is executed (or the timing when the modulation rate kh reaches the average modulation rate khave). It is. When the operation mode is switched to the speed fluctuation suppression mode, the modulation rate setting unit 14 gradually decreases the modulation rate limit value khmax so as to become the predetermined value kh1 (= 1.15).

  As described above, the motor drive system according to the present embodiment applies a direct current voltage (Ed) to the motor (36) that drives the load device (38) that generates a periodically varying load torque (τL). A power conversion circuit (34) that converts and applies voltages (Vu, Vv, Vw) and a torque fluctuation compensation amount (Iqsin *) that changes in accordance with the periodic fluctuation of the load torque (τL) are output. Based on the torque fluctuation compensation amount output unit (8) and the torque fluctuation compensation amount (Iqsin *), the motor output torque (τM) output from the motor is varied to suppress the rotational speed fluctuation of the motor (36). A speed fluctuation suppressing unit (2) for performing the function, designating one of the first operation mode (speed fluctuation suppression mode) or the second operation mode (overmodulation field weakening mode), and the operation Mo In the power conversion circuit (34) in the first operation mode and the operation mode designating section (9) having a function of suppressing the fluctuation amplitude of the torque fluctuation compensation amount (Iqsin *) before switching the mode. A function of suppressing the modulation factor (kh) to be equal to or lower than a first predetermined value (kh1), and a second that is different from the first predetermined value (kh1) in the second operation mode. And a modulation rate setting unit (14) having a function of suppressing the value to a predetermined value (kh2) or less.

  The operation mode designating unit switches the operation mode at a timing at which the modulation rate (kh) is an average modulation rate (khave) that is a moving average value of the modulation rate (kh).

The operation mode designating section (9) gradually decreases the fluctuation amplitude of the torque fluctuation compensation amount (Iqsin *) before switching the operation mode from the first operation mode to the second operation mode. And a function of gradually increasing the fluctuation amplitude of the torque fluctuation compensation amount (Iqsin *) during deceleration of the motor (36).
The second predetermined value (kh2) is higher than the first predetermined value (kh1).

  In addition, the motor drive system may be arranged such that the phase of the AC voltage (Vu, Vv, Vw) is such that the modulation factor (kh) does not exceed the first predetermined value (kh1) or the second predetermined value (kh2). And a correction phase calculation unit (13) for controlling.

  Due to these features, the motor drive system of the present embodiment can change the motor current and the current when switching between the speed fluctuation suppression control and the field weakening control (particularly the field weakening control in the overmodulation region) for reducing the vibration of the periodically varying load torque τL. This makes it possible to prevent fluctuations in the rotational speed, achieves both high efficiency in the low-speed rotation range and expansion of the drive range in the high-speed rotation range, and further increases the output, thereby reducing the motor 36 and the load device 38. Vibration can be realized.

[Second Embodiment]
Next, a motor drive system according to a second embodiment of the present invention will be described.
The hardware configuration of this embodiment is the same as that of the first embodiment, but the software configuration is slightly different. That is, in the present embodiment, even if the rotation speed detection value ω is constant, when the “event for which future acceleration is scheduled” occurs, the control switching command unit 9 is the first embodiment. The same processing as in the case of “accelerating” (steps S8 to S18 in FIG. 11) is executed. The case where “future acceleration is scheduled” is, for example, a case where the set temperature is lowered by the user during the cooling operation of the air conditioner, or a case where the set temperature is raised during the heating operation.

Next, a specific example of the operation of the present embodiment will be described with reference to the waveform diagrams shown in FIGS.
Prior to time t22 in FIG. 13A, the detected rotational speed value ω is constant. However, it is assumed that an “event scheduled for future acceleration” occurs at time t21. As a result, the fluctuation amplitude of the modulation factor kh is gradually reduced from time t21, and the fluctuation amplitude is made zero at time t22.

  When the motor driving device 110 (see FIG. 1) recognizes that the fluctuation amplitude of the modulation factor kh becomes zero at time t22, the motor driving device 110 increases the rotational speed command ω * from that point. When the rotational speed command ω * increases, the rotational speed detection value ω increases following this, as shown in FIG. At a subsequent time t23, when the average modulation rate command khave * (similar to the illustrated average modulation rate khave) reaches the predetermined value kh1, the operation mode is switched to the overmodulation field weakening mode by the control switching command unit 9. In response to this, the modulation rate setting unit 14 changes the modulation rate limit value khmax to the predetermined value kh2.

  As described above, according to the motor drive system of the present embodiment, even if the rotation speed detection value ω is constant, when the “event scheduled for future acceleration” occurs, the fluctuation amplitude of the modulation factor kh Can be reduced. Thereby, in addition to the effect similar to 1st Embodiment, there exists the further effect that an operation mode can be rapidly switched to an overmodulation field weakening mode.

[Third Embodiment]
Next, a motor drive system according to a third embodiment of the present invention will be described.
The hardware configuration of this embodiment is the same as that of the first embodiment, but the software configuration is slightly different. That is, in the processes of steps S12 and S14 (see FIG. 11) of the first embodiment described above, overmodulation field weakening control is stopped on condition that the amplitude limit value WI becomes zero. In contrast, the control switching command unit 9 of the present embodiment is different in that overmodulation field weakening control is stopped on condition that the amplitude limit value WI is equal to or less than a predetermined control stop amplitude value. Here, the “control stop amplitude value” is a value larger than zero.

Next, a specific example of the operation of this embodiment will be described with reference to the waveform diagrams shown in FIGS.
14A to 14C, the rotational speed detection value ω is accelerated from time t31, and accordingly, the fluctuation amplitude of the modulation factor kh gradually decreases. At time t32, the fluctuation amplitude of the modulation factor kh becomes equal to or less than the control stop amplitude value, and the speed fluctuation suppression control is stopped at that time. The subsequent operation is the same as that of the first embodiment. The control stop amplitude value is preferably set to a value within a range in which a shock caused by the stop of the speed fluctuation suppression control can be accepted by the device.

  As described above, according to the motor drive system of this embodiment, when the fluctuation amplitude of the modulation factor kh reaches the control stop amplitude value, the speed fluctuation suppression control can be stopped. Thereby, in addition to the effect similar to 1st Embodiment, there exists the further effect that the timing which stops speed fluctuation suppression control can be made earlier than the thing of 1st Embodiment.

[Fourth Embodiment]
Next, with reference to the front view shown in FIG. 15, the whole structure of the air conditioner A by this embodiment is demonstrated.
In FIG. 15, the air conditioner A includes an indoor unit 400, an outdoor unit 200, and a remote controller 410. The indoor unit 400 and the outdoor unit 200 are connected by a refrigerant pipe 300 and transmit / receive information to / from each other via a communication cable (not shown). The remote controller 410 is operated by the user and transmits an infrared signal to the remote control receiver 420 of the indoor unit 400. The contents of the signal are commands such as an operation request, a change in set temperature, a timer, an operation mode change, and a stop request. The air conditioner A performs air conditioning operations such as a cooling mode, a heating mode, and a dehumidifying mode based on these signals.

  The outdoor unit 200 includes a motor drive device 210 and a compressor 220. This motor drive device 210 is the same as any one of the motor drive devices of the first to third embodiments, and the compressor 220 is the same as the mechanical unit 120 in FIG. However, the compressor 220 is a twin rotary compressor, and the torque fluctuation occurs twice for one rotation of the mechanical angle.

  As described above, according to the present embodiment, by applying the motor driving device according to any one of the first to third embodiments to the air conditioner A, vibrations are generated over a wide range from the low speed rotation range to the high speed rotation range. Noise reduction is possible, overmodulation field weakening control is possible, the maximum rotation speed can be improved, and an air conditioner that can suppress shocks when switching the operation mode can be realized.

[Modification]
The present invention is not limited to the above-described embodiments, and various modifications can be made. The above-described embodiments are illustrated for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment. Further, it is possible to delete a part of the configuration of each embodiment, or to add or replace another configuration. Examples of possible modifications to the above embodiment are as follows.

(1) In each of the above embodiments, the position sensorless control is applied, and the rotation angle of the motor 36 is obtained by estimation as the estimated angular position θd. However, the rotation angle of the motor 36 may be detected using a rotation angle sensor.

(2) In each of the above-described embodiments, the speed fluctuation suppression current command Iqsin * is output by the speed fluctuation suppression control unit 8 shown in FIG. 3 so that the motor output torque follows the compressor load torque. However, there are various known control methods for causing the motor output torque to follow the compressor load torque, and “torque fluctuation compensation amount that fluctuates in response to periodically fluctuating load torque” is also various. Things are known. Therefore, various amounts other than the speed variation suppression current command Iqsin * may be applied as the “torque variation compensation amount”.

(3) In each of the above embodiments, an example in which a single rotary compressor, a twin rotary compressor, a reciprocating compressor, or the like is applied as the mechanical unit 120 has been described. it may be applied to a variety of loads that cause.

(4) In each of the above embodiments, the field correction control is realized by advancing the voltage phase θV in the voltage correction calculation unit 4. However, the d-axis current command calculation unit 1 sets a negative d-axis current command Id *. The field weakening control may be realized by outputting.

(5) Since the hardware of the controller 30 in the above embodiment can be realized by a general computer, the programs shown in FIGS. 11 and 12 may be stored in a storage medium or distributed via a transmission line. Good.
(6) Although the process shown in FIGS. 11 and 12 has been described as a software process using a program in the above embodiment, a part or all of the process is an ASIC (Application Specific Integrated Circuit). Alternatively, hardware processing using an FPGA (field-programmable gate array) or the like may be used.

2 Current command calculation section (speed fluctuation suppression section, speed fluctuation suppression means)
8 Speed fluctuation suppression control section (torque fluctuation compensation amount output section)
9 Control switching command section (operation mode designation section, operation mode designation means)
13 Correction Phase Calculation Unit 14 Modulation Rate Setting Unit (Modulation Rate Setting Unit)
30 Controller (computer)
34 Power conversion circuit 36 Motor 38 Load device (compression mechanism)
Ed DC voltage Iqsin * Speed fluctuation suppression current command (torque fluctuation compensation amount)
kh Modulation rate kh1 First predetermined value kh2 Second predetermined value khave Average modulation rate Vu, Vv, Vw Motor applied voltage (AC voltage)

Claims (8)

A power conversion circuit that converts a DC voltage into an AC voltage and applies it to a motor that drives a load device that generates a periodically varying load torque;
A torque fluctuation compensation amount output unit that outputs a torque fluctuation compensation amount that fluctuates in response to a periodic fluctuation of the load torque;
Based on the torque fluctuation compensation amount, a speed fluctuation suppressing unit that suppresses the rotational speed fluctuation of the motor by changing the motor output torque output by the motor;
Operation mode designation having a function of designating one of the first operation mode and the second operation mode, and a function of suppressing the fluctuation amplitude of the torque fluctuation compensation amount before switching the operation mode And
In the first operation mode, a function of suppressing the modulation factor in the power conversion circuit to be equal to or lower than a first predetermined value, and in the second operation mode, the modulation factor is different from the first predetermined value. A modulation rate setting unit having a function of suppressing to a predetermined value of 2 or less;
A motor drive device comprising: The motor drive device according to claim 1, wherein the operation mode designating unit switches the operation mode at a timing at which the modulation rate is an average modulation rate that is a moving average value of the modulation rate. The operation mode designating unit has a function of gradually reducing the fluctuation amplitude of the torque fluctuation compensation amount before switching the operation mode from the first operation mode to the second operation mode. The motor drive device according to claim 2. The motor drive device according to claim 3, wherein the operation mode designating unit has a function of gradually increasing a fluctuation amplitude of the torque fluctuation compensation amount during deceleration of the motor. The motor driving device according to claim 4, wherein the second predetermined value is higher than the first predetermined value. 6. The motor drive according to claim 5, further comprising: a correction phase calculation unit that controls a phase of the AC voltage so that the modulation factor does not exceed the first predetermined value or the second predetermined value. apparatus. A compression mechanism that compresses the refrigerant while generating a periodically varying load torque;
A motor for driving the compression mechanism;
A power conversion circuit that converts a DC voltage into an AC voltage and applies the same to the motor;
A torque fluctuation compensation amount output unit that outputs a torque fluctuation compensation amount that fluctuates in response to a periodic fluctuation of the load torque;
Based on the torque fluctuation compensation amount, a speed fluctuation suppressing unit that suppresses the rotational speed fluctuation of the motor by changing the motor output torque output by the motor;
Operation mode designation having a function of designating one of the first operation mode and the second operation mode, and a function of suppressing the fluctuation amplitude of the torque fluctuation compensation amount before switching the operation mode And
In the first operation mode, a function of suppressing the modulation factor in the power conversion circuit to be equal to or lower than a first predetermined value, and in the second operation mode, the modulation factor is different from the first predetermined value. A modulation rate setting unit having a function of suppressing to a predetermined value of 2 or less;
The air conditioner characterized by having. A power conversion circuit that converts a DC voltage into an AC voltage and applies it to a motor that drives a load device that generates a periodically varying load torque;
A computer,
A program applied to a motor drive device having
A torque fluctuation compensation amount output means for outputting a torque fluctuation compensation amount that fluctuates in response to a periodic fluctuation of the load torque;
Speed fluctuation suppression means for suppressing fluctuations in the rotational speed of the motor by changing the motor output torque output by the motor based on the torque fluctuation compensation amount;
Operation mode designation having a function of designating one of the first operation mode and the second operation mode, and a function of suppressing the fluctuation amplitude of the torque fluctuation compensation amount before switching the operation mode means,
In the first operation mode, a function of suppressing the modulation factor in the power conversion circuit to be equal to or lower than a first predetermined value, and in the second operation mode, the modulation factor is different from the first predetermined value. A modulation rate setting means having a function of suppressing the value to a predetermined value of 2 or less,
Program to function as.

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