CN104009692A - Motor control device and air conditioner using the motor control device - Google Patents

Abstract

Provided is a high-efficiency motor control device that reduces noise caused by resonance between a fan and a rotor. Equipped with: an inverter connected to a DC power supply, converting the DC power of the DC power supply into AC power with variable voltage and variable frequency, driving and controlling a 3-phase motor; The voltage applied by the motor; the higher-order component generation unit calculates the higher-order component of the fundamental wave of the voltage applied by the vector control unit; the voltage addition unit adds the applied voltage calculated by the vector control unit to the higher-order component generation unit. high-order component; and a PWM pulse generating part, which performs pulse width control on the inverter based on the signal of the voltage adding part, and for the resonance sound generated by the resonance of the 3-phase motor and its load, the high-order component generating part calculates to resonate The high-order component of the order represented by the ratio of the resonant frequency of the sound to the motor frequency, the voltage adding unit adds the high-order component to the applied voltage, thereby reducing the resonant sound.

Description

Motor control device and air conditioner using the motor control device

technical field

The present invention relates to a control method of a motor control device and an air conditioner using the control method of the motor control device. In particular, it relates to a technique for reducing the sound caused by a motor for a fan.

Background technique

Conventionally, in small fan motors used in air conditioners, noise generated at a specific rotational speed due to resonance between the rotor and the fan has been a problem. In order to solve the problem of noise caused by this resonance, anti-vibration rubber is provided on the rotor portion, or anti-vibration rubber is provided on the bearing portion of the fan to reduce the sound.

One of the causes is the distortion of the current waveform caused by the difference between the distortion of the induced voltage of the motor and the applied voltage, and various methods for eliminating the distortion of the current waveform have been proposed.

For example, Patent Document 1 discloses a technique in which a voltage for canceling torque ripple caused by distortion of an induced voltage is created in advance as an induced voltage ripple table and added to a command voltage.

In addition, Patent Document 2 discloses a control method that switches the modulation method according to a map of torque and rotation speed or two-dimensional coordinates of id current (d axis) and iq current (q axis) in order to realize high-efficiency operation.

Patent Document 1: Japanese Patent Laid-Open No. 2008-219966

Patent Document 2: Japanese Patent Laid-Open No. 2005-229676

Contents of the invention

However, the method of providing anti-vibration rubber in order to reduce the resonance sound between the fan and the rotor has the following problems: the structure of the motor and the fan becomes complicated and the cost becomes high.

In addition, the present inventors have confirmed through experiments that the resonance sound between the fan and the rotor cannot be eliminated by the technique of sinusoidalizing the current disclosed in Patent Document 1.

In addition, the present inventors have confirmed through experiments that in the method of switching the modulation method disclosed in Patent Document 2, there are cases where the resonance sound between the fan and the rotor can be eliminated and cases where the resonance sound between the fan and the rotor cannot be eliminated.

Therefore, an object of the present invention is to provide a highly efficient motor control device that reduces noise caused by resonance between a fan and a rotor.

The motor control device of the present invention includes: an inverter connected to a DC power supply for converting the DC power of the DC power supply into AC power of variable voltage and variable frequency to drive and control the three-phase motor; The voltage applied to the 3-phase motor that rotates the load; the higher-order component generation unit calculates the higher-order component of the fundamental wave of the applied voltage of the vector control unit; the voltage addition unit adds the higher-order component to the applied voltage calculated by the vector control unit The high-order component calculated by the sub-component generating unit; and the PWM pulse generating unit, which controls the pulse width of the inverter based on the signal of the voltage adding unit, wherein, for the resonance sound generated by the resonance of the 3-phase motor and its load, The higher-order component generation unit calculates a higher-order component of an order represented by the ratio of the resonance frequency of the resonance sound to the motor frequency, and the voltage addition unit adds the higher-order component to the applied voltage, thereby reducing the resonance sound.

According to the present invention, it is possible to provide a high-efficiency motor control device in which noise caused by resonance between a fan and a rotor is reduced.

Description of drawings

1 is a diagram showing the internal configuration of a motor control device according to a first embodiment of the present invention, and the relationship among the DC motor control device, a power supply, a three-phase AC synchronous motor, and a load.

2 is a diagram illustrating a method of adding a higher-order component of a higher-order component generation unit to a fundamental wave of a vector control unit using a rotating coordinate system in a voltage adding unit in the first embodiment of the present invention.

3 is a diagram showing a method of adding a higher-order component of a higher-order component generation unit to a fundamental wave of a vector control unit using a fixed coordinate system in a voltage adding unit in the first embodiment of the present invention.

FIG. 4 is a graph showing the characteristics of fan noise versus rotational speed and sound frequency.

FIG. 5 is a graph showing noise changes when 36-order higher-order components are applied for 130 min ⁻¹ .

FIG. 6 is a diagram showing an example of control in which high-order components of a plurality of orders are applied to the rotational speed.

7 is a diagram showing the internal configuration of a motor control device according to a second embodiment of the present invention, and the relationship among the DC motor control device, a power supply, a three-phase AC synchronous motor, and a load.

8 is a diagram showing a method of adding a higher-order component of a higher-order component generation unit to a fundamental wave of a vector control unit using a rotating coordinate system in a current addition unit in the second embodiment of the present invention.

9 is a diagram illustrating a method of adding a higher-order component of a higher-order component generation unit to a fundamental wave of a vector control unit using a fixed coordinate system in a current addition unit in the second embodiment of the present invention.

FIG. 10 is a diagram showing voltage waveforms of U-phase, V-phase, and W-phase in general three-phase modulation.

11 is a diagram showing voltage waveforms of U-phase, V-phase, and W-phase in a fixed-phase 60-degree switching method which is a two-phase modulation method.

12 is a diagram showing voltage waveforms of U-phase, V-phase, and W-phase in an upper stationary phase 120-degree switching method as a two-phase modulation method.

FIG. 13 is a diagram showing voltage waveforms of U-phase, V-phase, and W-phase in a lower stationary phase 120-degree switching method which is a two-phase modulation method.

14 is a diagram showing the internal configuration of a motor control device according to a third embodiment of the present invention, and the relationship among the DC motor control device, a power supply, a three-phase AC synchronous motor, and a load.

Fig. 15 is a diagram showing the configuration of an air conditioner according to a fourth embodiment of the present invention.

Explanation of reference signs

11, 108: Motor control device; 12: DC power supply; 13: Motor, 3-phase motor, 3-phase AC synchronous motor; 14: Load, fan; 15: Inverter, power conversion circuit; 16: DC bus current detection circuit ; 17, 18, 20: control device; 21: vector control unit; 22: high-order component generation unit; 23: voltage addition unit; 24: PWM pulse generation unit; 25: command current generation unit; 26: current addition unit 27: Voltage command operation section; 28: High-order component correction section; 29: Modulation mode selection section; 51: Power conversion main circuit; 52: Grid driver; 100: Air conditioner; 101: Outdoor unit; 102: Indoor 103: piping; 104: compressor; 105: heat exchanger (outdoor heat exchanger); 106: outdoor fan; 107: outdoor fan motor; 109: heat exchanger (indoor heat exchanger); 110: Blower.

Detailed ways

The motor control device of this embodiment includes: an inverter connected to a DC power supply, which converts the DC power of the DC power supply into AC power with variable voltage and variable frequency to drive and control the motor; A voltage applied to the motor that rotationally drives the load; a higher-order component generation unit that calculates a higher-order component of the fundamental wave of the voltage applied by the vector control unit; and a voltage adding unit that calculates the higher-order component of the voltage applied by the vector control unit adding a high-order component calculated by the high-order component generating unit to an applied voltage; and a PWM pulse generating unit that performs pulse width control on the inverter according to a signal from the voltage adding unit, wherein For the resonant sound generated by resonance with the load, the high-order component generating unit calculates the number of times expressed by the ratio of the resonant frequency of the resonant sound to the motor frequency (resonant frequency cycle of the resonant sound/motor frequency). a higher-order component, the voltage addition unit adds the higher-order component to the applied voltage.

In addition, the motor control device of this embodiment includes: an inverter connected to a DC power supply for converting the DC power of the DC power supply into AC power with variable voltage and variable frequency to drive and control the motor; Computing the current flowing through the motor; the high-order component generation unit computing the high-order component of the fundamental wave of the command current output as the output of the command current calculation unit; the current adding unit adding the command current to the command current the higher-order component calculated by the higher-order component generating unit; the vector control unit calculating the voltage applied to the motor based on the output of the current adding unit; and the PWM pulse generating unit based on the output of the vector control unit The signal performs pulse width control on the inverter, wherein, for the resonance sound generated by the resonance between the motor and the load, the high-order component generation unit calculates the ratio between the resonance frequency of the resonance sound and the motor frequency The current addition unit adds the higher-order component to the command current.

In addition, the motor control device of this embodiment includes: an inverter, connected to a DC power supply, converting the DC power of the DC power supply into AC power with variable voltage and variable frequency, and driving and controlling the motor; a vector control unit, Calculate the voltage applied to the motor that rotates and drives the load; the high-order component generation unit calculates the higher-order component of the fundamental wave of the voltage applied by the vector control unit; the PWM pulse generation unit includes a fixed two-phase modulation method. a plurality of modulation methods for controlling the pulse width of the inverter according to the signal of the voltage adding part; The secondary component correcting unit adds the higher-order component calculated by the higher-order component correcting unit to the applied voltage calculated by the vector control unit, wherein for the resonance sound generated by the resonance between the motor and the load, The higher-order component generation unit calculates a higher-order component of an order represented by the ratio of the resonance frequency of the resonance sound to the motor frequency (resonance frequency cycle of the resonance sound/motor frequency), and the voltage addition unit converts The higher-order component corrected by the higher-order component is added to the applied voltage.

In addition, the motor control device of this embodiment includes: an inverter connected to a DC power supply for converting the DC power of the DC power supply into AC power with variable voltage and variable frequency to drive and control the motor; Computing the current flowing through the motor; the high-order component generating unit calculating the high-order component of the fundamental wave of the command current output as the output of the command current computing unit; the current adding unit having a plurality of modulation modes corresponding to And the higher-order component correcting unit that corrects the higher-order component adds the higher-order component corrected by the higher-order component correcting unit to the command current; the vector control unit, based on the output of the current adding unit computing voltages applied to the 3-phase motor; and a PWM pulse generating section having a plurality of modulation schemes including a fixed 2-phase modulation scheme, and performing pulse width control on the inverter based on a signal from the vector control section, wherein For the resonant sound generated by the resonance between the motor and the load, the high-order component generator calculates the ratio of the resonant frequency of the resonant sound to the motor frequency (resonant frequency cycle of the resonant sound/motor frequency ), the higher-order component corrected by the higher-order component correction unit is added to the command current by the current addition unit according to a modulation method.

Embodiments for implementing the invention of the present application (hereinafter referred to as “embodiments”) will be described below with reference to the drawings. A motor control device according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 3 . FIG. 1 shows the internal structure of a motor control device 11 according to the first embodiment of the present invention, the motor control device 11 , a DC power supply 12 , and a three-phase AC synchronous motor (abbreviated as "motor" or "three-phase motor" as appropriate) 13 and the graph of the correlation between the load (fan) 14.

In FIG. 1 , a motor control device 11 is configured to include an inverter 15 as a DC-AC power converter and a control device 17 that controls the inverter 15 .

In addition, the control device 17 includes a PWM (Pulse Width Modulation: Pulse Width Modulation) pulse generation unit 24 , a vector control unit 21 , a higher-order component generation unit 22 , and a voltage addition unit 23 .

The motor control device 11 of the first embodiment is characterized in that the control device 17 includes a high-order component generation unit 22, and when the control device 17 performs PWM control on the inverter 15, the voltage from the high-order component generation unit 22 to the voltage addition unit 23 The high-order component of the added voltage. By this method, the noise caused by the resonance of the motor 13 and the fan 14 as a load is eliminated.

Before describing in detail the motor control device 11 of the first embodiment characterized by a method for eliminating noise caused by resonance, the noise caused by the resonance between the motor and the fan will be described first, and then the details of the first embodiment shown in FIG. 1 will be described in detail. Motor control device 11.

The noise generated by the fan 3 when the fan 14 ( FIG. 1 ) is driven by the motor 13 ( FIG. 1 ) will be described.

FIG. 4 is a graph showing an example of the noise versus rotational speed characteristics of the fan 14 . In addition, FIG. 2 and FIG. 3 will be described later.

In FIG. 4 , the horizontal axis is the rotational speed [min ⁻¹ ], the vertical axis is the sound frequency, and the density of the color represents the noise [dB]. In addition, rotation speed [min ⁻¹ ] is rotation speed/minute. In addition, it is equivalent to rpm (rotation per minute: revolutions per minute). In addition, in the following, for example, 520 revolutions per minute is simplified as 520 min ⁻¹ . The data is obtained by distributing the rotational speed every 10min ^-1 . The place where the color is thick appears near the sound frequency of 280Hz and 310Hz, but it can be seen that there are loud and small rotation speeds. The rotational speeds with the loudest sound here are around 780min ^-1 , 520min ^-1 , 390min ^-1 , 270min ^-1 , and 130min ^-1 . This is because the total amount of sound generated by the fan at low rotation is smaller than that at high rotation, so even if the absolute value of the noise at a frequency of 310 Hz is small, there is a feature that the sense of hearing deteriorates.

If the rotation speed is 780min ^-1 as a reference, the motor is a 3-phase AC synchronous motor, so if the number of poles of the motor is 8 poles, the electrical frequency of the motor is 52Hz [780/{60×(2/8)}]. It can be seen that the sound is generated by the excitation torque around 312 Hz of the sixth-order component with the fundamental frequency of 52 Hz. If we expand this idea, 520, 390, 310, 260, 190, 160, 130, 110 min ^-1 becomes 9 times, 12 times, 15 times, 18 times, 24 times, 30 times, 36 times, 42 times in turn. In the curve, the relationship between the frequency of each order and the fan speed is represented by a dotted straight line, and the point where the straight line intersects with the resonance frequency of the sound (solid line in the curve) represents the speed at which the resonant sound is generated and the frequency at this time.

Therefore, in order to eliminate the resonance sound of the fan 14 and the motor (rotor of the motor) 13 , countermeasures against these higher-order components are taken.

(Structure of the motor control unit: Part 2)

The configuration of the motor control device 11 according to the first embodiment of the present invention shown in FIG. 1 will be described again in detail.

As described above, FIG. 1 is a diagram showing the configuration of the motor control device 11 according to the first embodiment of the present invention, and the relationship among the DC power supply 12 , the motor 13 , and the fan (load) 14 .

In FIG. 1 , a motor control device 11 receives DC power from a DC power supply 12 and converts it into three-phase AC power. In addition, the motor (3-phase AC synchronous motor) 13 is supplied with 3-phase AC power from the motor control device 11 , is driven and controlled to rotate, and thereby drives the fan 14 to rotate.

Next, the motor control device 11 will be described in detail.

In FIG. 1 , as described above, the motor control device 11 is configured to include an inverter 15 (power converter) that converts DC power into three-phase AC power with variable voltage and variable frequency, and a controller that controls the inverter 15. device 17. In addition, the DC bus current detection circuit 16 is provided in the DC power supply of the inverter 15 .

In addition, the inverter 15 is configured to include a power conversion main circuit 51 composed of a diode element connected in antiparallel to a semiconductor switching element such as an IGBT (Insulated Gate Bipolar Transistor: Insulated Gate Bipolar Transistor), and a The PWM pulse signal 17A of the PWM pulse generator 24 generates a gate driver 52 that generates gate signals to the IGBTs (Sup, Sun, Svp, Svn, Swp, Swn) of the power conversion main circuit 51 .

IGBTs are connected in series to form one phase. IGBTs (Sup, Sun) are connected between DC power supplies 12 , and the connection point between the upper arm (Sup) and the lower arm (Sup) of each becomes an AC output terminal of the U-phase.

Similarly, the IGBTs (Svp, Svn) that are connected in series to form one phase are connected between the DC power supplies 12 , and the connection points of the respective upper arms (Svp) and lower arms (Svn) serve as V-phase AC output terminals.

In addition, the IGBTs (Swp, Swn) connected in series to form one phase are connected between the DC power sources 12 , and the connection points of the respective upper arms (Swp) and lower arms (Swn) serve as W-phase AC output terminals.

The control device 17 appropriately controls the above IGBTs (Sup, Sun, Svp, Svn, Swp, Swn) via the gate driver 52, so that the DC power of the DC power supply 12 is changed from the U phase, V phase, and W phase The AC output terminal outputs 3-phase AC power with variable voltage and variable frequency.

In addition, the control device 17 is configured to include a PWM pulse generation unit 24 , a vector control unit 21 , a higher-order component generation unit 22 , and a voltage addition unit 23 .

The vector control unit 21 calculates the fundamental wave applied voltage command 21B to the permanent magnet synchronous motor 13 and the permanent magnet synchronous motor 13 based on the DC bus current information (appropriately expressed as “phase current information”) 16A detected by the DC bus current detection circuit 16 . Motor rotational speed/phase information 21A of the synchronous motor 13 .

In addition, the higher-order component generating unit 22 outputs the higher-order component 22A of the voltage of the permanent magnet synchronous motor 13 to the voltage adding unit 23 based on the motor rotational speed/phase information 21A.

Further, voltage adding unit 23 adds higher-order component 22A of voltage to fundamental wave applied voltage command 21B, and outputs applied voltage command 23A.

In addition, PWM pulse generator 24 converts PWM pulse signal 17A based on applied voltage command 23A and a carrier signal contained inside.

In addition, the vector control of the vector control unit 21 can be performed by using, for example, "Discussion on New Vector Control Method of Permanent Magnet Synchronous Motor for High Speed (Discussion on New Vector Control Method of Permanent Magnet Synchronous Motor for High Speed)" Theory of Electricity D, Vol. 129 (2009) No.1pp.36-45", "Simple vector control of permanent magnet synchronous motor to the position sensor of home appliances (simple vector control of permanent magnet synchronous motors without position sensor for home appliances)" Theory of Electricity D, Vol.124 (2004) No.11pp.1133-1140 "shown in the way to achieve.

The DC bus current detection circuit 16 is connected to the DC bus on the negative side of the DC power supply 12 to obtain phase current information of mixed pulsating currents of U phase, V phase, and W phase. The acquired phase current information is output to the vector control unit 21 as DC bus current information (phase current information) 16A.

In addition, the method of acquiring phase current information can be realized by, for example, the method disclosed in Japanese Patent Application Laid-Open No. 2004-48886.

In the first embodiment, in order to reduce noise, a higher-order component is applied by a voltage higher-order component generating unit 22 and a voltage adding unit 23 shown below.

Next, operations of higher-order component generating unit 22 generating voltage higher-order component 22A and voltage adding unit 23 adding higher-order component 22A to fundamental wave applied voltage command 21B will be described with reference to FIGS. 2 and 3 .

In the higher-order component generation unit 22 , the higher-order components are generated based on the motor rotational speed/phase information 21A using preset values of G and φ in (Equation 2) and (Equation 4) described later, and the higher-order components are The secondary component 22A is output to the voltage addition unit 23 .

In the voltage adding unit 23 , the fundamental applied voltage command 21B output from the vector control unit 21 and the higher-order component 22A of the voltage output from the higher-order component generating unit 22 are added and output to the PWM pulse generating unit 24 .

As specific configurations, there are addition in a rotating coordinate system and addition in a fixed coordinate system. Next, these methods will be described in order.

The method of addition in the rotating coordinate system will be described with reference to FIG. 2 .

2 is a diagram showing the fundamental wave of the high-order component (higher-order component 22A of voltage) of the high-order component generation unit 22 transferred to the vector control unit 21 by the voltage adding unit 23 using the rotating coordinate system in the first embodiment of the present invention. (Fundamental wave applied voltage command 21B) A diagram of a method of addition.

In FIG. 2 , the vector control unit 21 uses the phase current information 16A based on the magnet flux direction (d-axis) of the motor rotor, and uses dq coordinates as a rotating coordinate system based on the d-axis and the right-angled direction (q-axis). The fundamental wave applied voltage command 21B (Vd ^* , Vq ^* ) and the motor rotational speed/phase information 21A are output on the shaft. In addition, Vd ^* is the fundamental wave applied voltage command 21B ( FIG. 1 ) with respect to the d axis and Vq ^* with respect to the q axis.

The higher-order component generation unit 22 generates higher-order components 22A-d (d-axis) and 22A-q (q-axis) on the dq coordinate axes based on the motor rotational speed/phase information 21A from the vector control unit 21 . In addition, the higher-order components 22A-d and 22A-q correspond to the higher-order component 22A in FIG. 1 .

The voltage addition unit 23 adds the fundamental applied voltage command (Vd ^* ) and the higher-order components 22A-d on the d-axis, and outputs d-axis applied voltage commands 23A-d.

In addition, the voltage adding unit 23 adds the fundamental wave applied voltage command (Vq ^* ) and the high-order component 22A-q on the q-axis, and outputs the applied voltage command 23A-q on the q-axis.

Also, applied voltage commands 23A-d, 23A-q are converted into U-phase, V-phase, and W-phase components by a conversion unit not shown, and input to PWM pulse generation unit 24 ( FIG. 1 ).

In addition, the method of addition in the fixed coordinate system will be described with reference to FIG. 3 .

3 is a diagram showing the fundamental wave of the high-order component (higher-order component 22A of voltage) of the high-order component generation unit 22 transferred to the vector control unit 21 by the voltage adding unit 23 using a fixed coordinate system in the first embodiment of the present invention. (Fundamental wave applied voltage command 21B) A diagram of a method of addition.

In FIG. 3 , vector control unit 21 outputs three-phase AC fundamental wave applied voltage commands 21B (Vu ^* , Vv ^* , Vw ^* ) in a fixed coordinate system and motor rotational speed/phase information 21A based on phase current information 16A.

Higher-order component generation unit 22 generates higher-order components 22A-U, 22A-V, and 22A-W of each phase based on motor rotational speed/phase information 21A from vector control unit 21 .

The voltage adding unit 23 adds the three-phase AC fundamental wave application voltage command 21B (Vu ^* , Vv ^* , Vw ^* ) and the higher-order component 22A- U, 22A-V, 22A-W output applied voltage commands 23A-U, 23A-V, 23A-W, respectively.

Next, a method for reducing the resonance sound between the fan 14 and the rotor (rotor of the motor 13 ) generated at n times the motor speed will be described.

The resonance between the fan 14 and the rotor ( 13 ) is caused by vibration in the rotational direction, and the voltage or current of each phase of the motor is different from the coordinate axis. The resonance between the fan and the rotor is related to the component of the coordinate axis of the rotating magnetic field generated by the synthesis of the three phases of the motor whose phases are different every 120 degrees (2π/3). Therefore, instead of the voltage of each phase of the three-phase motor (motor), it is appropriate to take measures to reduce the resonance sound by converting the dq coordinate system into the rotating coordinate system.

Generally, in vector control, voltage commands in dq coordinates are given as in (Expression 1).

[Formula 1]

$\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}^{<span\; class="notranslate">\; *</span>}\\ {\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}^{<span\; class="notranslate">\; *</span>}\end{array}\right]<span\; class="notranslate">\; =</span>\left[\begin{array}{c}\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}^{<span\; class="notranslate">\; *</span>}\\ \mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; E.</span>}}\end{array}\right]$

Here, r is the phase resistance of the motor, ω ₁ ^* is the command angular velocity, L _d , L _q are the inductances of the d-axis and q-axis, I _d ^* , I _q ^* are the command currents of the d-axis and q-axis, K _E is the induction voltage constant.

On the other hand, high-order components are calculated as in (Equation 2), and added as in (Equation 3) to obtain new voltage commands V _d ^** , V _q ^** .

[Formula 2]

$\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; dn</span>}}^{<span\; class="notranslate">\; *</span>}\\ {\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; qn</span>}}^{<span\; class="notranslate">\; *</span>}\end{array}\right]<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; E.</span>}}\left[\begin{array}{c}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; )</span>\\ <span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; )</span>\end{array}\right]$

[Formula 3]

$\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}^{<span\; class="notranslate">\; *</span><span\; class="notranslate">\; *</span>}\\ {\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}^{<span\; class="notranslate">\; *</span><span\; class="notranslate">\; *</span>}\end{array}\right]<span\; class="notranslate">\; =</span>\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}^{<span\; class="notranslate">\; *</span>}\\ {\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}^{<span\; class="notranslate">\; *</span>}\end{array}\right]<span\; class="notranslate">\; +</span>\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; dn</span>}}^{<span\; class="notranslate">\; *</span>}\\ {\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; qn</span>}}^{<span\; class="notranslate">\; *</span>}\end{array}\right]$

Here, V _dn ^* and V _qn ^* are the high-order components of voltage on the d-axis and q-axis, G _n is the amplitude coefficient of the n-order high-order component, n is the high-order order, θ _d is the phase of the d-axis, and φ _n is the n-order Initial phase of higher order components.

The inventors of the present invention confirmed through experiments that the sound that is n times the motor frequency is reduced by optimally selecting G _n and φ _n in (Expression 2). By applying the component voltage n times, it is possible to suppress the torque variation which becomes the source of the sound and reduce the sound.

As shown in FIG. 3 , the calculation formula of the higher-order component in the case of applying a voltage in the fixed coordinate system is (Expression 4).

[Formula 4]

$\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; Un</span>}}^{<span\; class="notranslate">\; *</span>}\\ {\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; vn</span>}}^{<span\; class="notranslate">\; *</span>}\\ {\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; W</span>}}^{<span\; class="notranslate">\; *</span>}\end{array}\right]<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; E.</span>}}\left[\begin{array}{c}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; n\&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; )</span>\\ <span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; n\&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; )</span>\\ <span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; n\&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; )</span>\end{array}\right]$

Here, V _Un ^* , V _Vn ^* , and V _Wn ^* are n-order voltage high-order components of U, V, and W phases.

In addition, (Expression 2) is expressed by the ratio _Gn to the amplitude of the voltage and the phase difference _φn to the voltage component, but higher-order components can be freely added by changing _Gn and _φn .

Next, an example of noise reduction at 130 min ⁻¹ is shown. Noise of 35dB was generated at 312Hz without applying high-order voltage. In Fig. 5, it is shown as follows: the horizontal axis is the initial phase φ ₃₆ of the 36th order, the vertical axis is the noise change value, and the amplitude coefficient G ₃₆ =0.5% of the high-order component of the 36th order makes φ ₃₆ from -180[ deg] to 180 [deg] and the noise change when G ₃₆ is changed when φ ₃₆ = -134 [deg]. In this way, by setting φ ₃₆ =−134deg and G ₃₆ =0.4%, the noise can be reduced by 19dB.

The method of applying the first (start) and last (end) when applying the high-order component will be described.

In the higher-order component generation unit 22 , the amplitude value of the higher-order component is gradually increased from 0 to a predetermined amplitude when the rotational speed at which the higher-order component is applied is reached (soft start). For example, applying the sixth-order component (Expression 2) corresponds to gradually increasing the coefficient of G ₆ (ratio to voltage fundamental wave amplitude).

In addition, when the high-order component is changed from the state where the high-order component is applied to the rotational speed at which the high-order component is not applied, the amplitude value of the high-order component is gradually reduced from a predetermined amplitude to 0 (soft end).

By adopting the soft start and soft end when applying the high-order component, there is no shock at the start and end of application of the high-order component, and stable control is achieved.

A case where a plurality of higher-order components are combined will be described using FIG. 6 . In FIG. 6 , the vertical axis represents the magnitude of the coefficient of the amplitude of each order, and the horizontal axis represents the fan speed. If the coefficient of the amplitude of each order is implemented according to the fan rotation speed as shown in FIG. 6 , the sound can be reduced at all rotation speeds for a certain resonance sound. In addition, in the example of FIG. 6, when a certain number of times appears near a certain rotation speed, it does not appear at other rotation speeds, but when there are multiple resonance points, even at the same number of times, it can be more set the speed.

The inventors of the present invention have confirmed that the appropriate value of the amplitude of the high-order component is 5% or less when the amplitude of the primary component (the square root of the sum of the squares of Vd and Vq) is used as a reference, and when it is greater than that causing the sound to become louder.

According to the first embodiment shown in FIG. 1 , the resonance sound of the fan and the rotor at a frequency n times higher than the motor frequency can be reduced by applying an n-order high-order component with a predetermined phase and amplitude.

The second embodiment will be described using FIGS. 7 to 9 . So far, it has been described that sound can be reduced by applying a higher-order component of a voltage, but it can also be achieved by applying a higher-order component of a current.

7 shows the internal structure of a motor control device 11 according to the second embodiment of the present invention, the motor control device 11 , a DC power supply 12 , and a three-phase AC synchronous motor (abbreviated as "motor" or "three-phase motor" as appropriate) 13 and a graph of the correlation between loads (fans) 14 .

In FIG. 7 , the configuration of the control device 18 of the motor control device 11 has the characteristics of the second embodiment.

In addition, the DC power supply 12 , the motor 13 , the fan 14 , the inverter 15 , and the DC bus current detection circuit 16 are the same as those of the first embodiment shown in FIG. 1 , and thus redundant descriptions are omitted.

The control device 18 includes a vector control unit 21 , a higher-order component generation unit 22 , and a PWM pulse generation unit 24 , and the vector control unit 21 includes a current command generation unit 25 , a current addition unit 26 , and a voltage command calculation unit.

The current command generation unit 25 acquires the phase current information 16A from the DC bus current detection circuit 16 , calculates the motor rotational speed/phase information 25A, and outputs it to the higher-order component generation unit 22 . In addition, command current generation unit 25 also outputs fundamental wave current command 25B to current addition unit 26 .

The higher-order component generating unit 22 outputs the higher-order component 22A of the current of the permanent magnet synchronous motor 13 to the current adding unit 26 based on the motor rotational speed/phase information 25A.

Current adding unit 26 adds current higher-order component 22A to fundamental wave application current command 25B, and outputs current command 26A.

The voltage command calculating unit 27 calculates a voltage command 27A based on the current command 26A and outputs it to the PWM pulse generating unit 24 .

Except for this, description of the same configuration as that of the first embodiment is omitted.

In the second embodiment, in order to reduce noise, a configuration is adopted in which a higher-order component is applied by a current higher-order component generation unit 22 and a current addition unit 26 as shown below.

Next, operations of higher-order component generating unit 22 generating higher-order component 22A of current and current adding unit 26 adding higher-order component 22A to fundamental current command 25B will be described with reference to FIGS. 8 and 9 .

In the higher-order component generation unit 22, the higher-order components are generated based on the motor rotational speed/phase information 21A using preset values of G and φ in (Equation 5) and (Equation 6) described later, and Higher-order component 22A is output to voltage addition unit 23 .

In the voltage adding unit 23 , the fundamental applied voltage command 21B output from the vector control unit 21 and the higher-order component 22A of the voltage output from the higher-order component generating unit 22 are added together and output to the PWM pulse generating unit 24 .

As specific configurations, there are addition in a rotating coordinate system and addition in a fixed coordinate system. Next, these methods will be described in order.

The addition method in the rotating coordinate system will be described with reference to FIG. 8 .

8 is a diagram showing the basis for transferring the high-order component (higher-order component 22A of current) of the high-order component generation unit 22 to the current command generation unit 25 by the current addition unit 26 using the rotating coordinate system in the second embodiment of the present invention. A diagram of the method of adding waves (fundamental wave current command 25B).

In FIG. 8 , the current command generation unit 25 uses the phase current information 16A as a rotating coordinate system based on the d-axis and the right-angled direction (q-axis) based on the magnet flux direction (d-axis) of the motor rotor. On the dq coordinate axes, the fundamental current command 25B (Id ^* , Iq ^* ) and the motor speed/phase information 25A are output. In addition, Id ^* is the fundamental wave current command 25B related to the d-axis and Iq ^* is related to the q-axis ( FIG. 7 ).

The higher-order component generation unit 22 generates higher-order components 22A-d (d axis) and 22A-q (q-axis) on the dq coordinate axes based on the motor rotational speed/phase information 25A from the current command generation unit 25 . In addition, the higher-order components 22A-d and 22A-q correspond to the higher-order component 22A in FIG. 7 .

The current addition unit 26 adds the fundamental current command (Id ^* ) to the higher-order components 22A-d on the d-axis, and outputs d-axis current commands 23A-d.

In addition, the current adding unit 23 adds the fundamental wave current command (Iq ^* ) to the high-order component 22A-q on the q-axis, and outputs the applied current command 23A-q on the q-axis.

Furthermore, applied current commands 23A-d, 23A-q are converted into U-phase, V-phase, and W-phase components by a conversion unit not shown, and input to PWM pulse generation unit 24 ( FIG. 7 ).

In addition, the addition method in the fixed coordinate system will be described with reference to FIG. 9 .

9 is a diagram showing the basis for transferring the higher-order component (current high-order component 22A) of the higher-order component generation unit 22 to the current command generation unit 25 by the current addition unit 26 using a fixed coordinate system in the second embodiment of the present invention. A diagram of the method of adding waves (fundamental wave current command 25B).

In FIG. 9 , current command generator 25 outputs three-phase AC fundamental wave current commands 25B (Iu ^* , Iv ^* , Iw ^* ) in a fixed coordinate system and motor rotational speed/phase information 25A based on phase current information 16A.

Higher-order component generation unit 22 generates higher-order components 22A-U, 22A-V, and 22A-W of each phase based on motor rotational speed/phase information 25A from current command generation unit 25 .

The current adding unit 26 adds the three-phase AC fundamental wave applied voltage command 25B (Iu ^* , Iv ^* , Iw ^* ) and higher-order components 22A-U, 22A in a fixed coordinate system for each phase (U, V, W) -V, 22A-W, and output applied voltage commands 23A-U, 23A-V, 23A-W, respectively.

Next, a method for reducing the resonance sound between the fan 14 and the rotor (rotor of the motor 13 ) generated at n times the motor speed will be described.

The vibration in the rotation direction is caused by the resonance between the fan 14 and the rotor ( 13 ), and the voltage or current of each phase of the motor is different from the coordinate axis. The resonance between the fan and the rotor is related to the component of the coordinate axis of the rotating magnetic field generated by the combination of three phases of the motor whose phases are different every 120 degrees (2π/3). Therefore, it is appropriate to take measures to reduce the resonance sound by converting the voltage of each phase of the three-phase motor (motor) into the dq coordinate system converted into the rotating coordinate system.

Generally, in vector control, the voltage command of the dq coordinates is given as (Expression 1).

Reduction of resonance sound can be achieved by defining the higher-order components of the current in (Expression 5) and adding them to I _d ^* and I _q ^* of the dq axes in (Expression 1).

[Formula 5]

$\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; dn</span>}}^{<span\; class="notranslate">\; *</span>}\\ {\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; dn</span>}}^{<span\; class="notranslate">\; *</span>}\end{array}\right]<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; n\&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; )</span>\\ {\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; n\&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; )</span>\end{array}\right]$

Alternatively, addition may be performed by Iu ^* , Iv ^* , and Iw ^* . The higher-order current in this case is shown in (Expression 6).

[Formula 6]

$\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; Un</span>}}^{<span\; class="notranslate">\; *</span>}\\ {\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; vn</span>}}^{<span\; class="notranslate">\; *</span>}\\ {\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; W</span>}}^{<span\; class="notranslate">\; *</span>}\end{array}\right]<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; n\&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; )</span>\\ {\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; n\&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; )</span>\\ {\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; n\&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; )</span>\end{array}\right]$

According to the first embodiment shown in FIG. 7 , by applying an n-order high-order component with a predetermined phase and amplitude, it is possible to reduce the resonance sound of the fan and the rotor at a frequency n times the motor frequency.

A motor control device according to a third embodiment of the present invention will be described with reference to FIGS. 10 to 14 . The third embodiment includes both the high-order component generating unit 22 and the voltage adding unit 23 of the first embodiment, and the control for switching the modulation method of the PWM control of the three-phase AC motor described later.

It is known that the modulation method is generally switched for the purpose of increasing efficiency, reducing sound, and reducing electrical noise.

In addition, including the 60-degree fixed phase switching method and the 120-degree fixed phase switching method described later, a method in which the potential of one phase is fixed and the other two phases are modulated at a predetermined electrical angle is called fixed two-phase modulation.

First, the stationary phase 60-degree switching method and the stationary phase 120-degree switching method as control methods of the motor control device will be described. In addition, the influence of this control method on sound will be described later, and the control combined with the high-order voltage application control will be described.

Here, the modulation method of the PWM control in the motor control device will be described.

The PWM control of a general 3-phase AC motor is 3-phase modulation (3-phase modulation method), but there is a method as follows: In the case of a 3-phase AC motor with Y wiring, use 2-phase modulation ( 2-phase modulation method) is performed.

That is, this method is as follows: taking advantage of the fact that the motor current is not determined by the phase voltage but by the phase-to-phase voltage, the phase-to-phase voltage is secured, and each phase voltage is always turned on for each predetermined period. Phase 1 is fixed to a high power supply level or a low power supply level sequentially at an electrical angle of π/3 (60°, 60°) to reduce the switching loss of the inverter.

In addition, in this method, as described above, one phase is potential-fixed within a predetermined section, and only the other two phases are modulated (PWM control). And, this potential-fixed phase repeats in sequence. Therefore, only 2 phases are modulated at any time, so it is called 2-phase modulation.

Hereinafter, the two-phase modulation method described above will be referred to as a fixed-phase 60-degree switching method.

Next, FIG. 11 shows the voltage waveform (voltage command) in the fixed phase 60-degree switching method, and this method will be described.

11 is a diagram showing voltage waveforms (voltage commands) of U-phase, V-phase, and W-phase in a fixed-phase 60-degree switching method as a two-phase modulation method.

In addition, FIG. 10 is a diagram showing voltage waveforms (voltage commands) of U-phase, V-phase, and W-phase in a general three-phase modulation system for reference.

In FIGS. 11 and 10 , the horizontal axis represents the angle [°] of the electrical angle, and the vertical axis represents the ratio of the voltage to the maximum voltage for each electrical angle, that is, the duty ratio [%].

In FIG. 11 , the W-phase is fixed at the lower limit voltage of the duty ratio 0% when the electrical angle is 0 degrees (equivalent to [°]) to 60 degrees.

In the voltage range from 0°C to 60°C in which the duty ratio of the W-phase is 0%, the U-phase and the V-phase form a voltage waveform in which the voltage difference and the phase with the W-phase are kept the same as those of the three phases shown in Fig. 10 The same relationship applies to the case of the modulation scheme. That is, from 0°C to 60°C, the W-phase has a duty ratio of 0%, so the U-phase and V layers are slightly lower than the original voltage values.

In addition, the U-phase is fixed at the upper limit voltage of a duty ratio of 100% between 60°C and 120°C. In this interval, the voltage waveforms of the V phase and the W phase are such that the voltage difference and the phase of the U phase maintain the same relationship as in the case of the three-phase modulation shown in Fig. 10, and therefore become slightly higher than the original voltage value. value. In addition, at 60 degrees, where the duty ratio of the U-phase suddenly becomes 100%, the voltages of the V-phase and W-phase rise rapidly.

In addition, the V-phase is fixed at the lower limit voltage of the duty ratio of 0% between 120°C and 180°C. In this interval, the W-phase and U-phase form a voltage waveform in which the voltage difference and phase with the V-phase maintain the same relationship as in the case of the three-phase modulation system shown in Fig. 10, and therefore become slightly lower than the original voltage value value. In addition, at 120 degrees at which the duty ratio of the V phase suddenly becomes 0%, the voltages of the W phase and the U phase drop sharply.

The control is repeated so that the operation waveforms of U-phase, V-phase, and W-phase as described above are obtained.

As shown in Figure 11, the phase-to-phase voltages of the U-phase, V-phase, and W-phase have different waveforms from the sine wave, but the U-phase-V-phase line-to-line voltage, the V-phase-W-phase line-to-line voltage, the W-phase-U Since the line-to-line voltages of the phases have sinusoidal waveforms, the motor 13 ( FIG. 14 ) and the fan 14 ( FIG. 14 ) driven by the three-phase line-to-line voltages operate in a manner similar to the case of the three-phase modulation method shown in FIG. 10 . same.

However, since the W phase is fixed at 0° to 60°, the U phase is at 60° to 120°, and the W phase is at 120° to 180°, it is possible to reduce the number of operations of the PWM control of the inverter 15 . Therefore, it is effective in reducing the power consumption of the inverter 15 .

In addition, in 0° to 360° and all the overlapping intervals, one of the U-phase, V-phase, and W-phase is fixed, and the remaining two phases are modulated. Therefore, it is 2-phase modulation as described above.

In addition, "Semiconductor power conversion circuit (semiconductor power conversion circuit)" published in March 1987 by the Institute of Electrical Engineering, pages 110, 111, 125, etc. disclose the same or similar techniques as above.

Next, the stationary phase 120-degree switching method in which the fixed interval per phase is longer than the above-mentioned stationary phase 60-degree switching method will be described.

In addition, the 120-degree switching method of the stationary phase includes an upper stationary phase 120-degree switching method in which the stationary phase is fixed at a high potential of DC voltage, and a lower stationary phase 120-degree switching method in which the stationary phase is fixed at a low potential of DC voltage. two kinds. Next, the 120-degree switching method of the upper stationary phase and the 120-degree switching method of the lower stationary phase will be described in order.

12 is a diagram showing voltage waveforms (voltage commands) of U-phase, V-phase, and W-phase in an upper stationary phase 120-degree switching method as a two-phase modulation method. In addition, the horizontal axis represents the angle [°] of the electrical angle, and the vertical axis represents the duty ratio [%] of the voltage.

In FIG. 12 , the U-phase is fixed at the upper limit voltage of a duty ratio of 100% between 30 degrees (corresponding to [°]) and 150 degrees.

In addition, the W-phase is fixed at the upper limit voltage of a duty ratio of 100% between 150°C and 270°C.

In addition, the V-phase is fixed at the upper limit voltage of a duty ratio of 100% between 270 degrees and (390) degrees.

As described above, each of the U phase, the V phase, and the W phase is fixed to a high power supply level within an electrical angle of 2π/3 (120 degrees) for each phase.

In addition, each of the U-phase, V-phase, and W-phase is controlled in a fixed interval to form a voltage waveform such that the voltage difference between the other phase and the above-mentioned phase and the phase are maintained as in the case of the three-phase modulation method shown in FIG. 10 same relationship.

Therefore, the U-phase, V-phase, and W-phase can be Y-connected, and the three-phase AC motor can be driven with respective line-to-line voltages.

FIG. 13 is a diagram showing voltage waveforms (voltage commands) of U-phase, V-phase, and W-phase in a 120-degree lower fixed-phase switching method as a two-phase modulation method. In addition, the horizontal axis represents the angle [°] of the electrical angle, and the vertical axis represents the duty ratio [%] of the voltage.

In FIG. 13 , the V-phase is fixed at the lower limit voltage of duty ratio 0% between 90 degrees (corresponding to [°]) and 210 degrees.

In addition, the U-phase is fixed at the lower limit voltage of the duty ratio 0% between 210°C and 330°C.

In addition, the W-phase is fixed at the lower limit voltage of duty ratio 0% between 330°C and (450°C) and between (−30)°C and 90°C.

As described above, each of the U-phase, V-phase, and W-phase is fixed to a low-potential power supply level within an electrical angle of 2π/3 (120 degrees) for each phase.

In addition, the section in which each of the U-phase, V-phase, and W-phase is fixed has a voltage waveform in which the voltage difference and phase between the other phases and the above-mentioned phase maintain the same relationship as in the case of the three-phase modulation method shown in FIG. 10 .

Therefore, the U-phase, V-phase, and W-phase can be Y-connected, and the three-phase motor can be driven with respective line-to-line voltages.

As above, the 120-degree switching method of the upper stationary phase and the 120-degree switching method of the lower stationary phase are sequentially fixed to a high power supply level or a low power supply level for each phase at an electrical angle of 2π/3 (120 degrees, 120 degrees). Therefore, the switching loss of the inverter can be reduced.

In addition, when the amplitude of the phase voltage becomes lower than the predetermined voltage value, when the control inappropriate situation shown in FIG. 12 and FIG. Method for applying 3-phase voltage.

In addition, Patent Document 2 discloses the same or similar technology as above.

The voltage fluctuation changes due to the change of the modulation method. For example, in the fixed-phase 60° switching method of the two-phase modulation method, the voltage discontinuity point appears six times in one rotation, so it affects multiples of six. For example, in the case where the lower stationary phase is switched at 120°, discontinuous points appear three times at 90, 210, and 330° in FIG. These explanations seem to be contradictory to the above explanation that the change of the modulation method does not affect the voltage between the lines, but the error of the modulation method is an error of a few percent or less relative to the primary amplitude of the applied voltage, so it is almost impossible to measure it, resulting in a negative effect on the sound. Influence.

Therefore, when the modulation method is changed, by adding the correction value to the phase φn and the amplitude Gn, the same sound reduction effect can be obtained even if the modulation method is changed.

Next, the configuration of the motor control device for reducing sound during modulation system switching control will be described.

14 is a diagram showing an internal configuration of a motor control device 11 according to a third embodiment of the present invention, and relationships among the motor control device 11 , a DC power supply 12 , a motor (three-phase motor) 13 , and a fan 14 .

In FIG. 14 , the configuration of the control device 20 of the motor control device 11 has the characteristics of the third embodiment.

In addition, the DC power supply 12 , the motor 13 , the fan 14 , the inverter 15 , and the DC bus current detection circuit 16 are the same as those of the first embodiment shown in FIG. 1 , and thus redundant descriptions are omitted.

The control device 20 is configured to include a vector control unit 21 , a PWM pulse generation unit 24 , a higher-order component generation unit 22 , a voltage addition unit 23 , a higher-order component correction unit 28 , and a modulation method selection unit 29 .

Vector control unit 21 acquires phase current information 16A from DC bus current detection circuit 16 , calculates motor speed/phase information 21A, and outputs it to higher-order component generation unit 22 and modulation method selection unit 29 . Also, the vector control unit 21 outputs a fundamental wave applied voltage command 21B to the voltage addition unit 23 .

The higher-order component generating unit 22 generates a higher-order component 22A based on the motor rotational speed/phase information 21A, and outputs the higher-order component 22A to the higher-order voltage correcting unit 28 .

The modulation method selection part 29 selects the fixed-phase 60-degree (or 120-degree) switching method of the 2-phase modulation method or the 3-phase modulation method according to the motor speed/phase information 21A, and outputs the modulation method selection signal 25A to the PWM pulse generation part 24 and a high-order component correction unit 28 .

The higher-order voltage correction unit 28 corrects the higher-order component based on the modulation method information 25A and the higher-order component 22A, and outputs the corrected higher-order component 26A to the voltage addition unit 23 .

Voltage addition unit 23 adds fundamental wave applied voltage command 21B to higher-order component 22A, and outputs applied voltage command 23A. PWM pulse generator 24 generates PWM pulse information 20A based on applied voltage command 23A and modulation method selection signal 25A.

With the above configuration, in the stationary phase 60-degree switching method and the stationary phase 120-degree switching method of the two-phase modulation method, the resonance sound of the fan and the rotor is reduced by applying a high-order component of the voltage.

Therefore, the third embodiment has the effects of high efficiency, sound reduction, and electrical noise reduction by changing the modulation method, and also has the effect of reducing the resonance sound between the fan and the rotor.

The third embodiment described above described the case of adding higher-order components of voltage, but the same effect as that of the method of adding higher-order components of voltage can be expected also in the method of adding higher-order components of current.

A motor control device according to a fourth embodiment of the present invention will be described. The fourth embodiment includes the higher-order component generation unit 22 and the current addition unit 26 of the second embodiment, and the higher-order component correction unit 28 and modulation method selection unit 29 of the third embodiment. The implementation method is to replace the high-order voltage of the third embodiment with a high-order current.

Next, a fifth embodiment will be described. In this embodiment, the motor control device 11 described in the first to third embodiments is applied to the motor control device 108 of the fan of the outdoor unit 101 of the air conditioner 100 .

Fig. 15 is a diagram showing a configuration example of an air conditioner 100 according to a fifth embodiment of the present invention. In FIG. 15, the air conditioner 100 is comprised including the outdoor unit 101 which exchanges heat with outdoor air, the indoor unit 102 which exchanges heat with indoors, and the piping 103 which connects both.

The outdoor unit 101 is configured to include a compressor 104 for compressing refrigerant, a heat exchanger 105 for exchanging heat with outdoor air, an outdoor fan 106 for blowing air to the heat exchanger 105, an outdoor fan motor 107 for rotating the outdoor fan 106, And a motor control device 108 that drives the outdoor fan motor 107 . In addition, the motor control device 11 of the first to fourth embodiments described above is applied to the motor control device 108 , the outdoor fan motor 107 corresponds to the three-phase motor 13 , and the outdoor fan 106 corresponds to the load 14 .

In addition, the indoor unit 102 is configured to include a heat exchanger 109 for exchanging heat with the room, and an air blower 110 for blowing air into the room.

In the fifth embodiment, the motor control device 11 of the first to fourth embodiments is applied to the air conditioner 100 as described above. That is, in the control device ( 17 , 18 , 20 ) that controls the inverter 15 , the resonance sound of the fan 14 and the rotor (motor 13 ) at the high-order frequency of the motor speed is reduced by applying a high-order component or selecting a modulation method.

According to the fourth embodiment, the noise can be reduced without using the anti-vibration rubber of the rotor portion of the outdoor fan motor 107 and the anti-vibration rubber of the fan portion, so that the quiet air conditioner 100 can be manufactured at low cost.

The embodiments of the present invention have been described above with reference to the drawings. However, the present invention is not limited to these embodiments and modifications thereof, and design changes and the like can be made within the scope not departing from the spirit of the present invention. Examples thereof are given below.

The configurations, functions, processing units, processing means, and the like of the above-described embodiments may be realized by hardware, for example, by designing a part or all of them with an integrated circuit. In addition, it can also be realized by software that can change the program. In addition, hardware and software can also be mixed.

In addition, the control lines and information lines indicate what is considered necessary in the description, and not all of the control lines and information lines are necessarily shown on the product. It can also be considered that virtually all structures are interconnected.

A part of the structure of one embodiment can be replaced with the structure of another embodiment, and the structure of another embodiment can also be added to the structure of one embodiment. In addition, addition/deletion/replacement of other configurations can be performed on a part of the configurations of each embodiment.

In order to clarify the description, the case where a fan is driven as a load is mainly described, but the present invention is effective for reducing sound caused by a structural resonance frequency, and the load is not limited to a fan.

The acquisition of the phase current information by the DC bus current detection circuit 16 can use a general method such as the method disclosed in Japanese Patent Application Laid-Open No. 2004-48886, and the detection method is not limited.

The vector control unit 21 can use the above-mentioned "Research on New Vector Control Method of Permanent Magnet Synchronous Motor for High Speed (Discussion of New Vector Control Method for High-speed Permanent Magnet Synchronous Motor)" Theory of Electricity D, Vol.129 (2009) No. .1pp.36-45", ""Simple vector control of permanent magnet synchronous motor to the position sensales of home appliances (simple vector control of position sensorless permanent magnet synchronous motors for home appliances)" Theory of Electricity D, Vol.124 (2004 ) No.11pp.1133-1140" and other general vector control methods, not limited to the control method.

In addition, although an IGBT is used as a switching element of the power conversion main circuit 51, it is possible to use a switching element of another semiconductor element, for example, a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor: Metal-Oxide-Semiconductor Field-Effect Transistor: Metal-Oxide-Semiconductor Field-Effect Transistor: transistor). In addition, as the composition of the element, a semiconductor element using SiC (Silicon Carbide, silicon carbide) or GaN (Gallium Nitride, gallium nitride) may be used.

It was explained that G (ratio of high-order wave amplitude to voltage fundamental wave amplitude) and φ (phase difference between fundamental wave component and high-order component) in the application formula of high-order components use the initially set values, but There is also a method of performing optimal control by appropriately changing G and φ in the vector control unit 21 according to the situation based on the information of the DC bus current detection circuit 16 .

The main function of the gate driver 52 in FIG. 1 is to improve the driving capability of the signal of the PWM pulse generating part 24, so if the output part of the PWM pulse generating part 24 has sufficient driving capability, or the function of the gate driver 52 is built into the PWM If the pulse generator 24 is used, the inverter 15 does not need to include the gate driver 52 .

Claims (8)

1. A motor control device, characterized in that it has: The inverter is connected to the DC power supply, converts the DC power of the DC power supply into AC power with variable voltage and variable frequency, and drives and controls the motor; a vector control unit calculating a voltage applied to the motor that rotationally drives a load; a higher-order component generation unit that calculates a higher-order component of a fundamental wave of the voltage applied by the vector control unit; a voltage adding unit that adds the higher-order component calculated by the higher-order component generation unit to the applied voltage calculated by the vector control unit; and The PWM pulse generation part controls the pulse width of the inverter according to the signal of the voltage addition part, The high-order component generation unit calculates a high-order component of an order represented by a ratio of a resonance frequency of the resonance sound to a motor frequency for a resonance sound generated by resonance between the motor and its load, and the voltage addition unit The higher order components are added to the applied voltage. 2. A motor control device, characterized in that it has: The inverter is connected to the DC power supply, converts the DC power of the DC power supply into AC power with variable voltage and variable frequency, and drives and controls the motor; a command current computing unit that computes the current flowing through the motor; a higher-order component generation unit that calculates a higher-order component of a fundamental wave of the command current output from the command current calculation unit; a current adding unit that adds the higher-order component calculated by the higher-order component generation unit to the command current; a vector control section calculating a voltage applied to the motor based on an output of the current adding section; and a PWM pulse generation unit that performs pulse width control on the inverter according to a signal from the vector control unit, The higher-order component generation unit calculates a higher-order component of an order represented by a ratio of a resonance frequency of the resonance sound to a motor frequency for a resonance sound generated by resonance between the motor and its load, and the current addition unit The higher-order components are added to the command current. 3. A motor control device, characterized in that it has: The inverter is connected to the DC power supply, converts the DC power of the DC power supply into AC power with variable voltage and variable frequency, and drives and controls the motor; a vector control unit calculating a voltage applied to the motor that rotationally drives a load; a higher-order component generation unit that calculates a higher-order component of a fundamental wave of the voltage applied by the vector control unit; a PWM pulse generation unit having a plurality of modulation methods including a fixed 2-phase modulation method, and controlling the pulse width of the inverter according to the signal from the voltage addition unit; a higher-order component correcting unit that corrects the higher-order component corresponding to a plurality of modulation schemes; and a voltage adding unit that adds the higher-order component calculated by the higher-order component correcting unit to the applied voltage calculated by the vector control unit, The high-order component generation unit calculates a high-order component of an order represented by a ratio of a resonance frequency of the resonance sound to a motor frequency for a resonance sound generated by resonance between the motor and its load, and the voltage addition unit The higher-order component corrected for the higher-order component is added to an applied voltage. 4. A motor control device, characterized in that it has: The inverter is connected to the DC power supply, converts the DC power of the DC power supply into AC power with variable voltage and variable frequency, and drives and controls the motor; a command current computing unit that computes the current flowing through the motor; a higher-order component generation unit that calculates a higher-order component of a fundamental wave of the command current output from the command current calculation unit; a higher-order component correcting unit that corrects the higher-order component corresponding to a plurality of modulation schemes; a current adding unit that adds the higher-order component corrected by the higher-order component correcting unit to the command current; a vector control section calculating a voltage applied to the motor based on an output of the current adding section; and a PWM pulse generation unit having a plurality of modulation methods including a fixed 2-phase modulation method, and controlling the pulse width of the inverter based on a signal from the vector control unit, The higher-order component generation unit calculates a higher-order component of an order represented by a ratio of a resonance frequency of the resonance sound to a motor frequency for a resonance sound generated by resonance between the motor and its load, The current addition unit adds the higher-order component corrected by the higher-order component correction unit to the command current according to a modulation method. 5. The motor control device according to claim 1, wherein: The amplitude of the higher-order component is 5% or less of the amplitude of the fundamental wave. 6. The motor control device according to any one of claims 1 to 5, wherein: The high-order component is 3m times of the fundamental wave, where m=1, 2, 3, . . . 7. The motor control device according to claim 1, wherein: The load of the motor is the fan. 8. An air conditioner, characterized in that, The motor control device according to claim 1 is mounted.