JP2015162998A - Active filter, motor drive device, compressor, and freezer using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an active filter capable of downsizing a device and reducing device cost, by not using a voltage sensor or a phase sensor for AC power source, and capable of starting up and normal operation of the active filter, by estimating power source frequency, power source phase, or phase order.SOLUTION: An active filter having a plurality of semiconductor elements includes an AC/DC converter circuit, connected to AC power source in parallel to a load, means for detecting an input current of the load, and a control part for controlling the AC/DC converter circuit. The control part estimates at least either an AC power source phase, frequency, or phase order, from a detection signal of the input current of the load, without using a detection sensor or a detection circuit for detecting an AC power source voltage or phase, before performing ON/OFF operation of the semiconductor elements, and performs ON/OFF operation of the semiconductor elements of the AC/DC converter circuit according to the estimated AC power source phase, frequency or phase order.

Description

  The present invention relates to an active filter, a motor drive device, a compressor, and a refrigeration apparatus using them, which suppress current harmonics of an AC power supply.

It is known that power supply harmonics generated from a rectifier that receives power from an AC power supply, a motor drive device, and the like have various effects on power equipment and control devices such as a transformer for transformation and a power capacitor.
In order to suppress power supply harmonics generated from these devices, an active filter connected in parallel with the load and compensating for harmonic currents is used.

JP 2006-25587 A Japanese Patent No. 4909857

"One Method of Power Supply Voltage Sensorless Three-Phase PWM Converter" described in 1994, IEEJ Transaction D, Volume 114, No. 12

In general, an active filter is controlled so as to detect an input current of a load (compensation target) in parallel, separate a harmonic component, and output an antiphase harmonic current (compensation current).
In order to output a reverse-phase harmonic current, information such as the voltage phase of the AC power supply, the power supply frequency, the phase sequence, and the output current of the active filter is necessary for controlling the active filter.

  However, in order to detect the voltage phase of the AC power supply, components such as an AC transformer and voltage sensor are required, as well as detection circuit wiring, insulation means (such as a photocoupler) and control for electrical insulation from the power supply An A / D converter, an input port, etc. are required, and the control device becomes complicated. In addition, there is a concern that the reliability of the apparatus may be reduced due to the failure of these components.

  As a control method of the three-phase PWM converter without detecting the voltage phase of the AC power supply, “One Method of Power Supply Voltage Sensorless Three-Phase PWM Converter” described in the IEEJ Transaction D, Volume 114, No. A method has been proposed in which a switching operation of the PWM converter is performed at an appropriate phase, and a power supply voltage phase is estimated using voltage and current information obtained there.

  Patent Document 2 (Japanese Patent Application Laid-Open No. 2006-25587) detects a zero cross signal of a power supply voltage before starting a PWM converter, reproduces a control system phase using a PLL control unit, and after starting a PWM converter, A method of switching to power supply voltage phase sensorless control is disclosed. According to this method, a power supply phase sensor is not required for control after startup, but a zero-cross signal detection circuit for a power supply voltage and a PLL control unit are required to detect phase information at startup.

Furthermore, a method of estimating the power supply phase and frequency from the diode rectified current when there is a DC load before starting the PWM converter is also disclosed (Patent Document 2).
However, these methods are mainly applied to PWM converters. A voltage / phase sensorless control method applied to the active filter is not disclosed.

  Therefore, the present invention reduces the size and cost of the apparatus by not using the voltage sensor or phase sensor of the AC power supply, estimates the power supply frequency, power supply phase, or phase sequence, and enables the activation of the active filter and normal operation. It aims to be.

  In order to achieve the above object, the present invention provides: “AC / DC conversion circuit having a plurality of semiconductor elements and connected in parallel with a load to an AC power supply; means for detecting an input current of the load; and the AC In an active filter having a control unit for controlling a DC / DC conversion circuit, the control unit detects the voltage or phase of the AC power supply before the semiconductor element of the AC / DC conversion circuit is turned ON / OFF. Without using a detection sensor and a detection circuit, the phase, frequency, or phase sequence of the AC power supply is estimated from the detection signal of the input current of the load, and the estimated phase, frequency of the AC power supply is estimated Or on / off operation of the semiconductor element of the AC / DC conversion circuit based on the phase order ”.

  According to the present invention, it is possible to reduce the size and cost of the apparatus by not using an AC power supply voltage sensor or phase sensor, to estimate the power supply frequency, power supply phase, or phase sequence, and to activate the active filter and perform normal operation. It becomes possible. The above-described solution of the present invention and the effects thereof will be described in detail in the following examples.

The block diagram of the active filter which shows the 1st Example of this invention. The control block diagram of the active filter of 1st Example of this invention. The internal block diagram of a harmonic separation part. An example of the detailed structure of electric current control. Explanatory drawing of the real phase coordinate axis and control coordinate axis of a power supply. The control frequency and phase adjustment block diagram by a load current signal. The current and phase fluctuation waveform of an example which show the estimation effect of the control phase of the present invention. The block diagram of the motor drive device which shows the 2nd Example of this invention. The block diagram of the motor drive unit and compressor which show the 3rd Example of this invention. The block diagram of the freezing apparatus which shows the 4th Example of this invention.

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

(Overall configuration)
FIG. 1 shows a load 10 that generates a harmonic current according to the first embodiment of the present invention, and a compensation current that is connected to an AC power supply in parallel with the load and cancels out a harmonic component contained in the input current of the load 10. It is a figure which shows the structure of the active filter to perform.

  As shown in FIG. 1, the active filter includes an AC / DC conversion circuit 4 connected to an AC power source 1 in parallel with a load 10 via a noise filter 2 and a reactor 3. The AC / DC conversion circuit 4 has an AC side connected to an AC power source via a noise filter and a reactor, and a smoothing capacitor 5 is connected between DC terminals on the DC side. The control unit 6 that controls the AC / DC conversion circuit 4, the current detection circuit (resistor) 7 that detects the DC bus current of the AC / DC conversion circuit 4, and the voltage detection circuit that detects the voltage of the smoothing capacitor 5 (divided voltage) Resistor) 8 and load input current detection means (current detection circuits 9a and 9b) for detecting the input current of the load 10.

  The AC / DC conversion circuit 4 is composed of six semiconductor elements (IGBT, MOSFET, etc.) as shown in FIG. The control unit 6 uses a semiconductor arithmetic element such as a microcomputer (MCU) or a digital signal processor (DSP).

(Control system configuration)
FIG. 2 is a functional block diagram showing functions of the control unit 6 of the active filter.

(Harmonic separation)
The harmonic separation unit 11 receives load current signals (i _Lu and i _Lv ) from the current detection circuits 9a and 9b that detect the input current of the load 10, and supplies power from the load current signals (i _Lu and i _Lv ). The frequency (fundamental wave) component is removed, and the harmonic components (i _Lhu , i _Lhv , i _Lhw ) are output.

(DC voltage control)
The voltage control unit 12 calculates the deviation between the DC voltage signal (E _d ) from the voltage detection circuit 8 and the DC voltage command value (E _d ^* ) to control the voltage across the smoothing capacitor 5, and the effective current Create a command value (i _qc ^* ).

(Current detection)
The current reproduction unit 13 calculates the AC current (i _u , i _v , i _w ) of the active filter using the detection signal (i _sh ) of the current detection circuit (resistor) 7 that detects the DC bus current. Since the processing in the current reproduction 13 is a well-known technique disclosed in applications such as inverter control, a detailed description thereof is omitted here. In this embodiment, in order to reduce the cost, a method of reproducing the alternating current from the direct current bus current is adopted. However, the alternating current may be detected using a means such as a current sensor.

(Command voltage calculation processing)
The current control unit 14 uses the harmonic components (i _Lhu , i _Lhv , i _Lhw ) separated from the load current as the current command value and the reproduced alternating current (i _u , i _v , i _w ). The three-phase voltage command (V _u ^* , V _v ^* , V _w ^* ) is calculated. Then, a PWM (Pulse Width Modulation) control unit 22 outputs an on / off control signal for each semiconductor element using the calculated three-phase voltage command.

(Details of harmonic separation)
FIG. 3 shows an example of a functional block configuration further inside the harmonic separator 11. First, the load current signal (i _Lu , i _Lv ) is converted into a control axis (dc-qc axis) by the uvw / dq conversion unit 11a based on the calculated control phase (θ _c ), and i _Ld and i _Lq are converted into i _Ld and i _Lq . calculate. Next, a low-pass filter (LPF) 11b removes the calculated harmonic components of i _Ld and i _Lq and extracts a DC component. Note that a DC component may be extracted by using a periodic average process or a moving average process instead of the low-pass filter (LPF).

Then, the DC component of the extracted dc-qc axis is converted again into three-phase AC coordinates by the dq / uvw converter 11c, and the fundamental wave component of the load current is calculated. The voltage of the smoothing capacitor 5 can be controlled by an effective current component from the AC power source to the active filter. Therefore, the active current command value (i _qc ^* ) is added to the input of the dq / uvw conversion 11c. Finally, the fundamental wave component is subtracted from the load current to calculate the harmonic current (i _Lhu , i _Lhv , i _Lhw ) including the effective current command.

(Command voltage calculation)
FIG. 4 shows an example of a functional block configuration further inside the current control unit 14. The harmonic component (i _Lhu , i _Lhv , i _Lhw ) calculated by the harmonic separation unit 11 and the current error of the alternating current (i _u , i _v , i _w ) calculated by the current reproduction unit 13 are proportionally integrated ( PI) A voltage command (ΔV _u ^* , ΔV _v ^* , ΔV _w ^* ) for controlling the alternating current is generated by being input to the controllers 14a, 14b, and 14c. Further, a three-phase AC power supply voltage signal (E _u , E _v , E _w ) is calculated from the dq / uvw converter 14d using the control phase (θ _c ), and the voltage command (ΔV _u ^* , ΔV _v is calculated). ^* , ΔV _w ^* ) and the three-phase voltage command (V _u ^* , V _v ^* , V _w ^* ) are calculated.

(Control phase)
Here, in the present embodiment, the AC power supply frequency and phase estimation unit 23 performs the AC power supply before the semiconductor element of the AC / DC conversion circuit 4 is turned on / off without using the voltage sensor or phase sensor of the AC power supply. 7. Estimate at least one of the seven power supply frequencies, phases, or phase sequences. Then, the control unit 6 causes the semiconductor element of the AC / DC conversion circuit 4 to be turned on / off based on the estimated power supply frequency, phase, or phase order of the AC power supply 7. Thus, the cost can be reduced or the apparatus can be reduced in size without using a voltage sensor or a phase sensor of an AC power supply. The control phase (θ _c ) when the active filter is operating is calculated by integral calculation using the phase calculation unit 17 of FIG.

The power source frequency, control phase initial value (θ _c0 ) and phase order estimating means before the activation of the active filter, and the control phase adjustment method during operation will be described below. As shown in FIG. 5, in this embodiment, the actual phase of the AC power supply is expressed by dq coordinates, and the control phase of the control unit 6 is expressed by dc-qc coordinates. The phase difference between the two coordinate axes is denoted as Δθ _c .

(Startup condition)
First, the activation condition (precondition) of the active filter of the present embodiment will be described. As the starting condition, it is assumed that the load to be compensated is already present before the starting, and the smoothing capacitor 5 is charged by the diode rectifying operation of the main circuit of the active filter. In other words, the activation condition of the active filter is after the load is activated. In addition, when the load falls below a predetermined value, the active current filter is stopped because the harmonic current is small. For example, when applied to an air conditioner, the active filter is activated when the air conditioner is activated first and the power supply current to the air conditioner exceeds a predetermined value (effective value of about 3 to 5 A). . Conversely, when the power supply current to the air conditioner becomes a predetermined value (effective value about 2 to 3 A) or less, the active filter is stopped.

(Power frequency, control phase initial value, phase order estimation method)
In the following, the load current detection signal (i _Lu and i _Lv ) is used before the active filter is activated, that is, without using the voltage sensor or phase sensor of the AC power supply before the ON / OFF operation of the semiconductor element. A method of estimating the power supply frequency, the control phase initial value (θ _c0 ), the phase sequence, and the effective value of the load current of the AC power supply 7 will be described.

FIG. 6 shows a functional block configuration inside the power source frequency and phase estimation unit 23 of the AC power source 7. In the present embodiment, the power supply frequency, phase, and phase sequence of the AC power supply 7 are estimated by repeating the loop of the power supply frequency and phase estimation unit 23. First, the detection signal (i _Lu and i _Lv ) of the load current is converted to the rotation coordinate (dc-qc axis coordinate) by using the control phase initial value (θ _c0 ) of the AC / DC conversion circuit 4 by the uvw / dq conversion unit 23a. The current is converted into a current, and the dc-qc axis current component (i _Ld , i _Lq ) is obtained. Since the initial initial control phase value (θ _c0 ) before the operation of this loop is unknown, it may be set appropriately.

Here, since the load current includes many harmonic current components, such as the input current (waveform 30 in FIG. 7) of the diode rectifier circuit shown in FIG. 7 as an example, the dc axis current (i _Ld ). Ripple component is large (see waveform 31 in FIG. 7). Therefore, the DC component of the dc-axis current (i _Ld ) of the current of the rotation coordinate (dc-qc axis coordinate) is extracted using the low-pass filter (LPF) 23b. Of course, instead of the above-described low-pass filter (LPF), periodic average processing or moving average processing may be used.

In this embodiment, the AC power supply 7 is calculated by calculating the frequency adjustment (Δω _s ) using the compensator ₂₃ c so that the current error between the DC component of the dc-axis current and the reference value i _Ld0 ^* is eliminated. And at least one of phase, frequency, and phase order. Specifically, this will be described below.

In general, the load current includes a fundamental reactive current in addition to the harmonic current component. For example, a DPF (Displacement Power Factor) value of a three-phase diode rectifier is about 0.92 to 0.96. For this reason, the DC component of the dc-axis current from the uvw / dq conversion unit 23a is not 0, but changes depending on the load characteristics, the inductance value of the AC power supply, and the magnitude of the load current. In general, the DC component reference value i _Ld0 ^* can be calculated by the following equation. i _Ld0 ^* = (1-DPF) × load current effective value
Here, the DPF value is about 0.92 to 0.96, which is obtained in advance from test data and circuit parameters.

Next, the control frequency (ω _s = ω _s0 + Δω _s ) of the AC / DC conversion circuit 4 is calculated by adding the frequency adjustment (Δω _s ) to the initial setting value (ω _s0 ) of the power supply frequency. Since the initial set value (ω _s0 ) of the first power supply frequency before starting is unknown, an appropriate value may be set in the range of 55 [Hz] or 50 [Hz] to 60 [Hz].

The control frequency initial value (θ _c0 ) is output by passing the control frequency (ω _s ) of the AC / DC conversion circuit 4 calculated last through the integrator 23d. The output control phase initial value (θ _c0 ) is returned to the uvw / dq converter 23a for use.

By repeating the control by the power supply frequency and phase estimation unit 23 in FIG. 6, the DC component of the dc-axis current can be converged to a predetermined value, and at the same time, the control frequency (ω _s ) can be converged to the predetermined value. Therefore, the power supply frequency can be estimated. Note that the commercial power system has power supplies with frequencies of 50 Hz and 60 Hz, which can be distinguished. Here, the convergence determination of the DC component of the dc-axis current can be determined by the difference between the maximum value and the minimum value during one cycle of the power supply being smaller than a predetermined value (about 10% or less of the effective load current value). it can.

  Here, if the compensator 23c employs an integral compensator or a proportional integral compensator (PI compensator), the steady-state deviation of the frequency error can be further reduced. Since the frequency estimation accuracy is high, the influence of the oscillator clock error of the control microcomputer and the fluctuation of the power supply frequency can be suppressed.

In FIG. 7, the simulation result of the power supply frequency and phase estimation part 23 mentioned above is shown. As initial conditions, an initial error between the actual phase of the power supply and the control phase was set to -90 °, and an initial setting value (ω _s0 ) of the power supply frequency was set to 55 Hz (power supply frequency was 50 Hz).

As can be seen from the simulation results shown in FIG. 7, the DC component of the dc-axis current (waveform 33) converges to a predetermined value (= 3A) after about 0.5 seconds by adjusting the closed loop shown in FIG. The control phase (waveform 34) was adjusted to match the power supply phase (waveform 35), and the phase error (waveform 36) was reduced to almost zero. Further, the control frequency (ω _s ) (waveform 37) was adjusted to coincide with the power supply frequency (= 50 Hz) despite the fact that the initial setting value (ω _s ^* ) was set to 55 Hz.

(Phase order judgment)
Next, a method for determining the phase order of the AC power supply will be described.
Depending on the power connection sequence on the AC power supply side, there are cases of normal order and reverse order. If the connection phase sequence of the input terminals of the active filter does not match the phase sequence of the control system, there is a risk that normal control cannot be performed. Therefore, as a simple method for determining the phase order, a method for determining the phase order of the AC power supply using the control configuration shown in FIG. 6 will be described.

  In the control configuration shown in FIG. 6, the control phase is matched with the power supply phase by adjusting the frequency so that the DC component of the dc-axis current becomes a predetermined value. However, this operation is performed when the phase sequence preset in the control system and the phase sequence of the power supply match. When they do not match, the DC component and frequency of the dc-axis current are predetermined. Does not converge (stable) to the value.

  Therefore, the phase sequence of the AC power supply is determined using the above phenomenon (not converged). In other words, when the DC component or frequency of the dc-axis current converges (stable), it matches the phase order of the control system. Therefore, when the phase order is determined to match and does not converge (stable), the control system Therefore, it is determined that the phase order does not match. When it is determined that the phase order does not match, the phase order of the control system is quickly reversed and the phase and frequency are re-estimated.

  Here, as a specific stability determination method, the control shown in FIG. 6 is performed based on whether or not the DC frequency of the estimated control frequency or dc-axis current amount is stabilized after a predetermined time has elapsed. By such processing, the active filter can operate normally without knowing the phase sequence of the power supply in advance.

(Estimation of input active current)
Next, estimation of the effective current component of the load current will be described.
The effective current component of the input current can be estimated from the DC component of the qc-axis current after the DC component of the dc-axis current and the control frequency converge in the control configuration of FIG. In other words, since the control phase is adjusted so that the dc-axis current (reactive current component) becomes a predetermined value corresponding to the reactive current, the DC component of the qc-axis current at that time becomes the effective current component of the load current.

  Further, the effective current component of the estimated load current is compared with a predetermined value, and the active filter is activated when it exceeds the predetermined value. By doing so, when the load current is small (the harmonic current is below the regulation value), the active filter can be stopped and the operation loss of the active filter can be reduced, so that the efficiency of the entire apparatus is improved. Of course, in addition to the effective current component of the load current, the effective value, average value, amplitude value, and the like of the load current may be compared with predetermined values to determine the activation of the active filter.

(Power supply voltage estimation method)
Next, a method for estimating the power supply voltage will be described.
Normally, the voltage of the commercial power supply may fluctuate within a rated value ± 10%. Therefore, in this embodiment in which the power supply voltage is not directly detected, if the rated value of the power supply voltage is set to the initial value of the control system, an error occurs in the output voltage command of the active filter when the power supply voltage fluctuates.

Therefore, a method for estimating the power supply voltage will be described. The AC / DC conversion circuit 4 operates as a three-phase diode rectifier and charges the DC-side smoothing capacitor 5 while the active filter is stopped (the semiconductor element is not turned on / off). The relationship between the DC voltage (E _dc ) in this state and the phase voltage effective value (Vs) of the power supply voltage is expressed by the following equation.

Edc = Vs × √3 × √2 (1)

Therefore, the power supply voltage can be calculated backward from the detected DC voltage (E _dc ) according to the equation (2).

Vs = Edc / (√3 × √2) (2)

In addition, using the estimated power supply voltage, it is possible to determine the overvoltage or the undervoltage of the AC power supply by comparing the overvoltage set value and the undervoltage set value of the power supply. The foregoing has described the method for estimating the power supply frequency, phase and phase sequence before the active filter is operated. If the control system is initialized using the estimated information, the active filter can be activated.

(Phase error calculation)
Next, a method for adjusting the control phase while the active filter is operating will be described.
If the phase shift between the actual phase (dq coordinate) of the AC power supply and the control phase (dc-qc coordinate) of the control unit 6 is defined as a phase error Δθ _c (see FIG. 5), the active filter in the dc-qc coordinate The voltage equation is expressed by equation (3).


Where V _dc : active filter output voltage dc-axis component, V _qc : active filter output voltage qc-axis component, i _dc : active filter AC current dc-axis component, i _qc : active filter AC current qc-axis component , R: resistance value of the reactor, L _s : inductance value of the reactor, ω _s : power supply frequency, E _s : power supply voltage.

Therefore, in order to obtain the phase error Δθ, the equations (3) to (4) are obtained.


In the equation (4), the differential value of the dc-qc axis current has a value only during a transient change, and becomes zero when the power supply frequency and the compensation current are in a constant steady state. Moreover, since the resistance value (R) of the reactor is actually very small, the influence of the related term of the resistance value (R) can be approximated to zero. Therefore, when the approximation of equation (4) is performed, a practical phase error estimation equation (5) is obtained.


Actually, since the dc-axis component (V _dc , V _qc ) of the active filter output voltage in equation (5) cannot be directly detected, the voltage command value is used instead of the voltage detection value.

Specifically, as shown in FIG. 2, a three-phase voltage command (V _u ^* , V _v ^* , V _w ^* ) to the PWM control unit 22 is converted into a rotating coordinate system (dc−) in the uvw / dq conversion 19. qc-axis coordinate system), and the dc-qc-axis component is obtained. However, since the obtained dc-qc axis component of the voltage command includes a harmonic component, the DC component (V ^* _{d_LPF,} V) of the dc-qc axis component of the voltage command is processed by the low pass filter (LPF) 20. ^* _{q_LPF} ). Similarly, the alternating current (i _u , i _v , i _w ) calculated in the current reproduction 13 is also converted into a rotating coordinate system (dc-qc axis coordinate system) by the uvw / dq conversion 15, and a low-pass filter (LPF) 16 To calculate the DC component (I _{d_LPF,} I _{q_LPF} ) of the dc-qc axis component of the AC current.

Accordingly, in the phase error estimation 21, the phase error (Δθ _c ) can be calculated by the equation (6).

[Delta] [theta] _c = tan ^{-1 _{([V * d_LPF + ω s × L}} s × I q_LPF ] / ^{_{[V * q_LPF -ω s × L s}} × I d_LPF ]) (6)

Where V ^* _{d_LPF} : DC component of dc-axis voltage, V ^* _{q_LPF} : DC component of qc-axis voltage, I _{d_LPF} : DC component of dc-axis current, I _{q_LPF} : DC component of qc-axis current, ω _s : AC power supply Frequency _, L _s : Reactor inductance value.

(Control phase adjustment)
Further, as shown in FIG. 2, the control phase is adjusted by the equations (7) and (8) by using the phase lock loop (PLL) control unit 18 so that the phase error obtained by the equation (6) is eliminated. To do.



In the above, the control phase adjustment method has been described using the phase error obtained from the voltage command of the control system and the detected alternating current while the active filter is operating.

(Description of startup sequence)
Finally, the activation filter activation sequence of the present embodiment will be described.
The startup sequence is “load current magnitude determination” → “frequency and phase adjustment, phase order determination” → “startup determination” → “control initialization” → “normal operation”.

Hereinafter, the processing content of each operation state will be briefly described.
(I) Judgment of load current magnitude When the load current magnitude is calculated from the load current detection signal and exceeds a predetermined value (frequency and phase adjustment is possible), go to “Frequency and phase adjustment, phase order judgment” move on.
(II) Frequency and phase adjustment, phase sequence determination If the magnitude of the load current is sufficient, the control frequency and control phase are adjusted using the load current detection signal. If the predetermined time has elapsed, it is checked whether the adjusted control frequency and control phase are stable, and the phase order is determined.
(III) Activation Determination The effective current component of the load current is calculated, and it is determined whether the activation of the active filter is necessary.
(IV) Initialization of control When it is determined that the active filter needs to be activated, the control system is initialized using the estimated frequency and phase, and the normal operation is started.
(VI) Normal operation The semiconductor element of the AC / DC conversion circuit 4 is turned on / off to output a compensation current.
Also, the effective current component of the load current is calculated and compared with the set value for stopping operation. When the load is smaller than the set value for stopping operation, the operation of the active filter is stopped.

(Effect of the invention)
By using the present invention, it is possible to estimate information such as the power supply frequency, the power supply phase, and the phase sequence required for the activation and normal operation of the active filter without using the voltage sensor or phase sensor of the AC power supply. Since the AC voltage and phase sensor can be omitted, the control board can be reduced in size and cost.

(Motor drive device)
A motor driving apparatus according to a second embodiment of the present invention will be described with reference to FIG. In this embodiment, the active filter of the first embodiment and a motor drive circuit are combined to form a device.
As shown in FIG. 8, the motor drive device 100 of this embodiment is mainly composed of a motor drive circuit 101 and an active filter of the first example. The motor drive circuit 101 includes a rectifier circuit 102 and an inverter 103, and drives the motor 104.

The circuit configuration and control method of the active filter are the same as those in FIGS. 1 and 2 of the first embodiment. The active filter detects an input current of the motor drive circuit 101, outputs a negative-phase harmonic current, and suppresses a harmonic component of the power supply current to a power supply harmonic regulation value or less.
According to the present invention, the active filter does not use a power supply voltage sensor or a phase sensor, and the control board can be downsized and the apparatus cost can be reduced.

(Compressor)
FIG. 9 is a block diagram of a motor driving apparatus for driving the compressor and the compressor motor according to the third embodiment of the present invention.
FIG. 9 does not show the detailed structure of the compressor 205, but a rotary compressor, a scroll compressor, or the like is adopted, and a compression mechanism section is provided therein. This compression mechanism section is driven by a compressor motor 208. Is done. If the compression mechanism unit is a scroll compressor, it is composed of a fixed scroll and a turning scroll, and the turning scroll makes a turning motion with respect to the fixed scroll, thereby forming a compression chamber between the scrolls.

The compressor 205 has a compressor motor 208 having a permanent magnet synchronous motor therein, and the compressor is driven by driving the compressor motor 208 by the motor driving device 100 of the second embodiment. . As shown in FIG. 9, the motor drive device 100 includes a motor drive circuit 101 and an active filter 105.
According to this embodiment, the harmonic component of the power supply current of the compressor can be suppressed below the power supply harmonic regulation value by using the motor drive device of the second embodiment.

(Refrigeration equipment)
FIG. 10 shows a configuration diagram of a refrigeration apparatus such as an air conditioner or a refrigerator according to the fourth embodiment of the present invention.

  The refrigeration equipment 200 is a device that harmonizes the air temperature, and is configured by connecting an outdoor unit and an indoor unit through a refrigerant pipe 206. Here, the indoor unit includes an indoor heat exchanger 201 that performs heat exchange between the refrigerant and air, and an outdoor fan 203 that blows air to the indoor heat exchanger 201. The outdoor unit includes an outdoor heat exchanger 202 that performs heat exchange between the refrigerant and air, an outdoor fan 204 that blows air to the outdoor heat exchanger 202, and a compressor 205 that compresses and circulates the refrigerant.

  The compressor 205 uses the compressor of the third embodiment, adopts a rotary compressor, a scroll compressor, and the like, and includes a compression mechanism section and a compressor motor 208 inside. The motor 208 is driven by a motor drive board 207. The motor drive board 207 suppresses the harmonic component of the power supply current below the power supply harmonic regulation value by using the motor drive device of the second embodiment.

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Noise filter 3 Reactor 4 AC / DC conversion circuit 5 Smoothing capacitor 6 Control part 7 Current detection circuit 8 Voltage detection circuit 9a, 7b Current detection circuit 10 Load 11 Harmonic separation part 11a uvw / dq conversion 11b Low-pass filter 11c dq / uvw conversion 12 Voltage control unit 13 Current reproduction 14 Current control 14a, 14b, 14c Proportional integral (PI) control 14d dq / uvw conversion 15 uvw / dq conversion 16 Low pass filter 17 Phase calculation unit 18 PLL control 19 uvw / dq conversion 20 Low-pass filter 21 Phase error estimator 22 PWM control 23 Phase estimation 23 a uvw / dq conversion 23 b Low-pass filter 23 c Compensator 23 d Integrator 30 Input current waveform 31 dc-axis current waveform 32 DC component waveform of qc-axis current 33 dc-axis current DC component waveform 34 control Phase waveform 35 Power supply phase waveform 36 Phase error waveform 37 Control frequency waveform 100 Motor drive device 101 Motor drive circuit 102 Rectifier circuit 103 Inverter 104 Motor 105 Active filter 200 Refrigeration device 201, 202 Heat exchanger 203, 204 Fan 205 Compressor 206 Piping 207 Motor drive board 208 Compressor motor

Claims (11)

An AC / DC conversion circuit having a plurality of semiconductor elements and connected to an AC power supply in parallel with a load; and means for detecting an input current of the load;
In an active filter including a control unit for controlling the AC / DC conversion circuit,
The controller is
Before using the detection sensor and the detection circuit for detecting the voltage or phase of the AC power supply before the ON / OFF operation of the semiconductor element of the AC / DC conversion circuit, the detection signal of the input current of the load is used. Estimating at least one of the phase, frequency, or phase sequence of the AC power source,
An active filter for operating an ON / OFF operation of the semiconductor element of the AC / DC conversion circuit based on the estimated phase, frequency, or phase order of the AC power supply. In claim 1,
The controller is
Based on the control phase of the AC / DC conversion circuit, the input current of the load is converted into a current of rotational coordinates (dc-qc axis coordinates), and a DC component is extracted from the converted dc axis current. An active filter characterized by estimating at least one of a phase, a frequency, or a phase order of the AC power supply by controlling to be a predetermined value. In claim 2,
An integral compensator or a proportional integral compensator is used to calculate the adjustment amount of the control frequency or control phase of the AC / DC conversion circuit so that the DC component of the dc-axis current becomes a predetermined value. The active filter. In claim 3,
The control unit determines whether the phase sequence of the control unit and the phase sequence of the AC power supply coincide with each other according to whether the DC component of the control frequency or the dc-axis current is stable for a predetermined time or more. An active filter characterized by that. In claim 3,
After the DC component of the dc axis current reaches a predetermined value, the effective component of the input current of the load is estimated from the DC component of the qc axis current,
An active filter characterized by determining whether or not the active filter can be activated by comparing the estimated effective component of the input current with a predetermined value. In claim 1 or 2,
Before operating the AC / DC converter circuit, the voltage across the smoothing capacitor (Edc) is detected, and the effective value of the phase voltage (Vs) of the AC power supply is estimated by the following arithmetic expression. filter.
Vs = Edc / (√3 × √2) (Phase error calculation)
In claim 1 or 2,
The controller is
When the ON / OFF operation of the semiconductor element of the AC / DC conversion circuit is performed, the three-phase voltage command value and the detected value of the AC current are rotated by the control phase of the AC / DC conversion circuit to the PWM control unit. Each is converted into a coordinate system (dc-qc axis coordinate system), a DC component is extracted from the voltage and current of the dc-qc axis, and the control phase and AC power source of the AC / DC conversion circuit are expressed by the following approximate arithmetic expression An active filter characterized by estimating an error (Δθc) with respect to the phase.
Δθc = tan−1 ([V * d_LPF + ωs × Ls × Iq_LPF] / [V * q_LPF−ωs × Ls × Id_LPF])
Where V * d_LPF: DC component of dc-axis voltage, V * q_LPF: DC component of qc-axis voltage, Id_LPF: DC component of dc-axis current, Iq_LPF: DC component of qc-axis current, ωs: AC power supply frequency, Ls : Reactor inductance value. In claim 1 or 7,
The controller is
In order to eliminate an error (Δθc) between the control phase of the AC / DC conversion circuit and the phase of the AC power source when the semiconductor element of the AC / DC conversion circuit is turned on / off, the error An active filter characterized by adjusting a control frequency or a control phase by calculating a control frequency adjustment (Δωs) from (Δθc). A rectifier circuit that converts alternating voltage to direct current;
A motor drive circuit having an inverter for converting direct current to alternating current;
An active filter connected in parallel to the motor drive circuit and generating a compensation current that cancels out harmonics included in the input current of the motor drive circuit;
A motor driving device using the active filter according to claim 1 as the active filter. A compression mechanism for compressing the refrigerant;
A compressor motor that drives the compression mechanism;
In the compressor provided with the motor drive device which drives the motor for compressors,
A compressor using the motor drive device according to claim 9 as the motor drive device. A compressor for compressing the refrigerant;
An outdoor heat exchanger that exchanges heat between refrigerant and air;
An outdoor fan that blows air to the outdoor heat exchanger;
The compressor mechanism of the compressor is driven by a compressor motor,
A motor driving device according to claim 10 is used as a motor driving device for driving the compressor motor.