JP3345563B2 - Motor control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply apparatus for rectifying an AC power supply to improve a power factor, and more particularly to a motor control apparatus for controlling a motor by changing a DC voltage.

[0002]

2. Description of the Related Art FIG.
No. 8 discloses a driving device for an electric motor disclosed in Japanese Patent Application Laid-Open No. H8-208. 10, 1 is an AC power supply, 2 is a full-wave rectifier circuit, 10 is a smoothing circuit, 12 is an inverter, 15 is a motor, 17 is a phase current detector for detecting an instantaneous current flowing through one phase of the motor 15, 19 Is a motor speed control circuit, which outputs an output signal of the phase current detector 17 and a speed command ω of the motor.
And a DC voltage command VDC * for setting the voltage between both ends of the smoothing circuit 10, and outputs a drive signal to the inverter 12. Reference numeral 3 denotes a power factor improving circuit, which includes a reactor 4, a diode 9, a transistor 5, a transistor current detector 16 for detecting a current flowing through the element, and a full-wave rectifier circuit 2.
A converter for inputting the output voltage of the smoothing circuit 10, the voltage across the smoothing circuit 10, the output signal of the transistor current detector 16, and the DC voltage command VDC * from the motor speed control circuit 19, and operating the transistor 5 to improve the input power factor Drive circuit 18
And is composed of

Next, the operation will be described. In FIG. 10, the output of an AC power supply 1 is rectified by a full-wave rectifier circuit 2 via a reactor 4, and the obtained pulsating voltage is smoothed by a smoothing circuit 10 to obtain a DC power supply. The operation of the power factor improvement circuit 3 is performed by the converter drive circuit 18 by the DC voltage value A of the smoothing circuit 10, the DC voltage command value B from the motor speed control circuit 19, and the instantaneous input voltage value obtained from the output of the full-wave rectifier circuit 2. When C is input, an instantaneous current value is calculated from these values.

Further, the transistor 5 is driven such that the value of the current flowing through the transistor 5 detected by the transistor current detector 16 coincides with the calculated instantaneous current value. The input current is controlled by the power factor correction circuit 3 into a sinusoidal waveform having the same phase as the power supply voltage. When the transistor 5 is on, a current flows from the AC power supply 1 through a path of the full-wave rectifier circuit 2, the reactor 4, and the transistor 5, and energy is stored in the reactor 4.

Next, when the transistor 5 is turned off, a current flows from the AC power supply 1 through the path of the full-wave rectifier circuit 2, the reactor 4, the diode 9, and the smoothing circuit 10. At this time, since the energy of the reactor 4 is released to generate a voltage, it is added to the power supply voltage of the AC power supply 1 and
Since this is applied to 0, the DC voltage can be boosted.

A motor speed control circuit 19 calculates an optimum frequency and voltage based on an arbitrary speed command ω * of the motor 15 and an output signal of the phase current detector 17, and sends an AC voltage command E to the inverter 12. . Inverter 12 operates based on AC voltage command E, and power is supplied from smoothing circuit 10 to drive electric motor 15. Further, the motor speed control circuit 19 obtains a DC voltage command value B based on the input DC voltage command VDC *, the output signal of the phase current detector 17, and the AC voltage command E, and outputs the same to the control circuit 18.

[0007]

SUMMARY OF THE INVENTION In the prior art,
Since the motor drive device is configured as described above,
When the output power of the motor is small, the DC voltage supplied to the inverter is high, and the power loss in the inverter and the motor increases, or the DC voltage rises abnormally.

Further, when the DC voltage supplied to the inverter is changed by the power factor improving circuit, the voltage applied to the motor changes, and the DC voltage repeatedly increases and decreases.

Further, since the ripple voltage of the AC power supply frequency is superimposed on the DC voltage, a similar ripple component is superimposed on the voltage applied to the motor, and this component causes the motor and the compressor to vibrate greatly. There were challenges.

[0010] The present invention aims to solve the above-mentioned problems by improving the efficiency of the inverter and the electric motor and enabling high-efficiency operation of the device.

[0011]

According to a first aspect of the present invention, there is provided an electric motor control device, comprising: a rectifier circuit and a smoothing circuit for converting AC power from an AC power supply to DC; and a switching element operable to improve a power factor. A power factor improvement circuit having an inverter and a reactor, an inverter connected to the smoothing circuit and outputting an arbitrary voltage and frequency, an electric motor connected to the inverter, and the electric motor based on a detected current value of a load current detector. And an inverter control means for calculating the output of the motor and controlling the speed of the motor, and operating the switching element of the power factor improvement circuit so as to change the DC voltage value of the smoothing circuit stepwise according to the motor output. Things.

A motor control apparatus according to a second aspect of the present invention includes a rectifier circuit and a smoothing circuit for converting AC power from an AC power supply to DC, a switching element and a reactor operating to improve a power factor. A power factor correction circuit that calculates the input power based on the detected current value of the power supply current detector;
An inverter connected to the smoothing circuit and outputting an arbitrary voltage and frequency, a motor connected to the inverter, and an inverter control unit for controlling the speed of the motor, according to input power of the power factor improvement circuit, The switching element of the power factor correction circuit is operated so that the DC voltage value of the smoothing circuit is changed stepwise.

According to a third aspect of the present invention, there is provided a motor control device comprising: a rectifier circuit and a smoothing circuit for converting AC power from an AC power supply to DC; a power supply having a switching element and a reactor operating to improve a power factor. Rate improvement circuit,
An inverter connected to the smoothing circuit and outputting an arbitrary voltage and frequency; a motor connected to the inverter; and a speed control of the motor by calculating input power of the inverter based on a detected current value of a load current detector. And controlling the switching element of the power factor correction circuit so as to change the DC voltage value of the smoothing circuit stepwise according to the input power of the inverter.

According to a fourth aspect of the present invention, there is provided a motor control device comprising: a rectifying circuit and a smoothing circuit for converting AC power from an AC power supply to DC; a switching element and a reactor operating to improve a power factor. Rate improvement circuit,
An inverter connected to the smoothing circuit and outputting an arbitrary voltage and frequency; a motor connected to the inverter; and speed control of the motor by calculating output power of the inverter based on a detected current value of a load current detector. And controlling the switching element of the power factor correction circuit so as to change the DC voltage value of the smoothing circuit stepwise according to the output power of the inverter.

According to a fifth aspect of the present invention, in the motor control device, the speed of the motor is continuously controlled by the inverter.

In a motor control device according to a sixth aspect of the present invention, the voltage applied to the motor is controlled by the inverter according to the pulsating voltage of the smoothing circuit.

According to a seventh aspect of the present invention, in the motor control device, when any one of the input power of the inverter, the output of the motor, or the inverter duty of the inverter is equal to or less than a predetermined value, the power factor improving circuit is provided. Are stopped.

According to an eighth aspect of the present invention, there is provided a motor control device comprising: a rectifier circuit and a smoothing circuit for converting AC power from an AC power supply into DC; a power supply having a switching element and a reactor operating to improve a power factor. Rate improvement circuit,
An inverter connected to the smoothing circuit and outputting an arbitrary voltage and frequency, a motor connected to the inverter, and inverter control means for controlling the speed of the motor; and controlling the inverter output voltage and the DC voltage of the smoothing circuit. The inverter and the switching elements of the power factor correction circuit are controlled so as to be changed simultaneously by an arbitrary change rate.

In a ninth aspect of the present invention, the switching device of the power factor correction circuit is controlled so that the DC voltage of the smoothing circuit is varied stepwise.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram of an electric motor control device according to an embodiment of the present invention. Parts similar to those of the conventional device are denoted by the same reference numerals. In FIG. 1, 1 is an AC power supply, 2
Is a full-wave rectifier circuit, 3 is a power factor correction circuit, 4 is a reactor,
5 is a transistor, 6 is a power supply current detector, 7 is a converter drive circuit for driving the transistor 5, 8 is converter control means for outputting a drive signal to the converter drive circuit 7,
9 is a diode. The power factor improvement circuit 3 includes a reactor 4, a transistor 5, a current detector 6, a converter drive circuit 7, a converter control means 8, and a diode 9, and is connected to the output side of the full-wave rectifier circuit 2. 10 is a smoothing circuit, 11 is a load current detector, 15 is a motor, 12
Is an inverter that outputs an arbitrary frequency and voltage to supply electric power to the motor 15, 13 is an inverter driving circuit that inputs an inverter driving signal and drives the inverter 12,
Reference numeral 4 denotes a DC voltage command VDC * set based on the speed command ω *, a voltage across the smoothing circuit 10 and an input signal from the load current detector 11, a converter operation command to the converter control means 8, and an inverter drive signal. A driving device for an electric motor, comprising inverter control means for outputting to the circuit 13.

FIG. 2 is a block diagram of the inverter control means 14, wherein 50 is a DC voltage detecting section for detecting the voltage of the smoothing circuit 10, 51 is a load current detecting section for detecting a current flowing through the load current detector 11, and 52 is a load current detecting section. The motor output calculation unit calculates the output of the motor 15 from the input values from the DC voltage detection unit 50 and the load current detection unit 51. 53 is a speed control unit which receives a speed command ω *, signals from the motor output calculation unit 52 and the DC voltage detection unit 50, and outputs an inverter duty signal, a converter operation command signal, and a DC voltage command VDC *;
An inverter drive circuit 1 receives the inverter duty signal from the speed controller 53 to generate a PWM signal, and
Reference numeral 3 denotes a PWM signal generation unit that outputs an inverter drive signal.

Next, the operation of this embodiment will be described. In FIG. 1, when a speed command ω * is input to the inverter control means 14, a target DC voltage command VDC * is determined based on the command, and a converter operation command and a DC voltage command VDC * are given to the converter control means 8. Is entered. Converter controller 8 receives a smoothed DC voltage of smoothing circuit 10 and converts the smoothed DC voltage to DC voltage command V
A drive signal is output to the converter drive circuit 7 so that the current matches the DC * and the current flowing through the power supply current detector 6 becomes a sinusoidal current synchronized with the power supply voltage, and the transistor 5 is driven by the converter drive circuit 7 Is done.

The power factor improving circuit 3 boosts the voltage due to the switching operation of the transistor 5 and the energy storage effect of the reactor 4, and reduces the boosted pulsating voltage to the smoothing circuit 10.
To output a stable DC voltage.

The inverter control means 14 generates an inverter drive signal based on the input speed command ω * and outputs it to the inverter drive circuit 13 so that the inverter drive circuit 13
2 to drive the motor 15 to match the speed command ω *, thereby controlling the speed of the motor 15. The load current detector 11 detects a current input to the inverter,
It is input to the inverter control means 14 as a load current detection signal.

In FIG. 2, the motor output calculation unit 52 includes:
The output of the electric motor 15 is calculated from the DC voltage detection value of the smoothing circuit detected by the DC voltage detection unit 50 and the current value of the load current detector 11 detected by the load current detection unit 51. The speed control unit 53 generates a target DC voltage command VDC of the smoothing circuit 10 based on the inverter duty signal, the speed command ω *, and the motor output calculated by the motor output calculation unit 52.
Is output to the converter control means 8 together with the converter operation command signal. When the operation of the apparatus is started, a preset initial value is output as the DC voltage command VDC *. PWM
The signal generator 54 generates a PWM signal based on the inverter duty signal and outputs the PWM signal to the inverter drive circuit 13.

FIG. 3 is a diagram showing a change characteristic, in which the DC voltage VDC of the smoothing circuit 10, the inverter duty D of the inverter 12, and the output voltage VINV with respect to the motor output are shown.
Shows the relationship. In response to the increase in the motor output, the inverter duty D of the inverter 12 is increased. When the inverter duty D is almost maximized, the DC voltage VDC is increased to an arbitrary value so that the output voltage of the inverter 12 becomes substantially constant. Is reduced.

Further, with respect to the increase of the motor output, the DC voltage VDC is varied stepwise and high while repeating the above operation. When the motor output decreases, the above-described reverse operation is repeated. V0 of the DC voltage VDC is
The switching of the transistor 5 of the power factor correction circuit 3 is stopped, and V1 to V3 are the times when the power factor correction circuit 3 is operating.

Here, the value of the DC voltage VDC may be any number of levels. Further, instead of the motor output shown in FIG. 3, this may be replaced with the input or output power of the inverter 12 and the input power of the power factor correction circuit 3 for control.

FIG. 4 is a diagram showing a change characteristic, wherein the output voltage VINV of the inverter 12 with respect to the inverter duty D of the inverter 12, the inverter 12 and the motor 15 are shown.
In relation to the total efficiency η. The relationship between the inverter duty D and the output voltage VDC is the same as in FIG. 3, and is as described above. As the value of the inverter duty D increases irrespective of the DC voltage VDC, the switching loss in the inverter 12 decreases and the efficiency η increases due to the decrease in the ripple current of the current flowing through the motor 15 by the PWM control. Is shown. An object is to vary the DC voltage VDC and the inverter duty D in accordance with the output of the motor 15, and to drive the motor 15 continuously with high efficiency.

In order to increase the output of the motor 15, the inverter control means 14 outputs a DC voltage command VDC * to the converter control means 8. DC voltage V in power factor correction circuit 3
The DC is stepped up from V0 to a target value. On the other hand, an inverter duty D is set by the inverter control means 14, and the electric motor 15 is driven by the inverter 12 by the inverter duty D.

For example, when the DC voltage VDC is V1, to further increase the output of the motor 15, the inverter 12
Increase the inverter duty D of. When the inverter duty D rises and reaches the maximum, the DC voltage VDC is raised to V2 by the power factor improving circuit 3. At this time, the inverter duty D of the inverter 12 is reduced and set so that a voltage substantially equal to that before the DC voltage VDC is increased is applied to the motor 15. Further, in order to increase the output of the electric motor 15, the same operation as described above is repeated. At the time of the maximum output of the motor 15, the DC voltage VDC is boosted to V3 by the power factor improvement circuit 3 by the same operation, and the motor 15 is driven at the maximum inverter duty D.

In order to reduce the output of the motor 15,
Conversely, when the inverter duty D of the inverter 12 is reduced and reaches an arbitrary value, the DC voltage VDC is reduced to a predetermined voltage. At this time, the inverter duty D of the inverter 12 is set so that a voltage substantially equal to that before the DC voltage VDC is reduced is applied to the motor 15. Further, in order to reduce the output of the motor 15, the same operation is repeated. At the time of the minimum output of the motor 15, the DC voltage VDC is reduced to V1 by the power factor improvement circuit 3 and then stopped to reach V0. The output of the motor 15 is varied by varying the inverter duty D.

FIG. 5 is a diagram showing the change characteristics. The output voltage VINV, the DC voltage VDC, and the inverter duty D of the inverter 12 at the variable timing of the DC voltage VDC are shown.
Is shown over time. The purpose is to keep the output of the motor constant by controlling the voltage applied to the motor 15 to be substantially constant. When the DC voltage VDC increases, the voltage rises from V1 to V2 at an arbitrary rate from time a to time b.
Meanwhile, the inverter duty D is reduced so that the output voltage VINV of the inverter 12 becomes substantially constant.

Therefore, the voltage applied to the motor 15 is substantially constant, and the motor output does not change. Further, the DC voltage V
The same operation is performed when DC increases and when DC voltage VDC decreases. The change of the DC voltage VDC and the inverter duty D at the variable timing of the DC voltage VDC may be simultaneously changed at an arbitrary rate to control the output voltage VINV of the inverter 12 to be substantially constant.

FIG. 6 is a diagram showing a change characteristic, showing a hysteresis characteristic of the DC voltage VDC and the inverter duty D with respect to the motor output at a variable timing of the DC voltage VDC. For example, when the DC voltage VDC is V1, to increase the motor output from point a to point b, the inverter duty D is increased to a maximum.

Further, in order to increase the motor output, the DC voltage VDC is increased to V2, and the output voltage V
INV reduces the inverter duty D at the same time to be substantially constant. Thereafter, the motor output is increased to the target point b by increasing only the inverter duty D.

Conversely, when the DC voltage VDC is V2, to reduce the motor output to point a, the inverter duty D is reduced to an arbitrary value. Further, to reduce the motor output, the DC voltage VDC is reduced to V1 and the inverter 1
2, the inverter duty D is simultaneously increased so that the output voltage VINV becomes substantially constant. Thereafter, only the inverter duty D is reduced to the target point a.
Here, DC voltages VDC are shown for V1 and V2, but other voltage values are similarly controlled.

FIG. 7 is a diagram showing a change characteristic, wherein the ripple voltage of the DC voltage VDC and the output voltage VIN of the inverter 12 are shown.
This shows the relationship of V. The DC voltage VDC smoothed by the smoothing circuit 10 is generally superimposed with the ripple voltage of the frequency component of the AC power supply 1 and becomes a pulsating voltage like Vrip. Here, if the inverter duty D of the inverter 12 is controlled to be constant, a voltage including the ripple component is output to the output voltage VINV of the inverter 12, and the motor output pulsates in synchronization with the ripple voltage. .

In order to remove the ripple component, the ripple voltage at both ends of the smoothing circuit 10 was measured and input to the inverter control means 14 to remove the ripple voltage.
The motor 15 is driven by generating a PWM signal and outputting an output voltage VINV which is not affected by a ripple component from the inverter 12.

In FIG. 7, when the DC voltage VDC is a and the inverter output voltage is VINV and the motor output is stable and almost constant, the inverter duty of the inverter 12 is increased in order to increase the efficiency of the inverter 12 and the motor 15. D is maximized and at the same time the DC voltage VDC is reduced to b for operation.

In order to increase the efficiency of the inverter 12 and the motor 15 even when the inverter duty D is smaller than the maximum value for a certain period of time,
The inverter 12 is operated with the DC voltage VDC reduced so that the inverter duty D of the inverter 12 is maximized.

FIG. 8 is a control flowchart for determining the set value of the DC voltage VDC, which is processed by the inverter control means 14. 7 and 8, the inverter 1
The output voltage maximum value VINVp-p is calculated from the output voltage VINV of (2) (a). The ripple voltage minimum value Vrip min at both ends of the smoothing circuit 10 is read (b). Here, the ripple voltage minimum value Vrip min may be a value stored in advance in a memory such as a microcomputer or an actually measured value obtained by measuring a DC voltage VDC actually smoothed by the smoothing circuit 10.

The maximum output voltage value VINVp-p is compared with the minimum ripple voltage value Vripmin. If they match, the process proceeds to Y, and if they do not match, the process proceeds to N (c). In the case of N, if VINVp-p> Vrip min, VDC is raised, and if VINVp-p <Vrip min, VDC is lowered (d). Until VINVp-p = Vripmin (c),
The process of (d) is repeated.

When proceeding to Y, the inverter 12 controls with the maximum inverter duty D which can remove the ripple component, and controls the DC voltage V so that the minimum DC voltage Vrip is obtained.
The motor control is performed with rip being the value of b, so that the motor 15 has a stable motor output without pulsation and the motor 1
5 is operated with high efficiency because a current having a small ripple component flows.

FIG. 9 shows the transistor 5 of the power factor correction circuit 3.
5 is a flowchart for determining whether to stop the switching operation of the present embodiment. The purpose of stopping the switching operation of the transistor 5 is to prevent the DC voltage VDC from being unnecessarily boosted when the motor output is low, and to reduce the efficiency of the inverter 12 when the DC voltage VDC is unnecessarily high. This is to prevent the deterioration of the data.

The flowchart of FIG. 9 will be described. It is determined whether the DC voltage VDC is a stepped minimum boosted voltage value. VDC>
If V1, proceed to Y, otherwise proceed to N (A). N, that is, at the time of the minimum boost voltage value, the motor output POUT and the predetermined power value P
When POUT <P1, 1 advances to Y, that is, step-up unnecessary,
Otherwise, proceed to N (b). When Y, transistor 5
Stops the switching operation of (c).

Here, the predetermined power value P1 is a preset value such as stored in a memory such as a microcomputer. P
OUT indicates the DC power input to the inverter 12 obtained by actually measuring the load current detector 11,
The same effect can be obtained with the inverter duty D of 2.

In this process, when the motor output is equal to or less than the predetermined value, the inverter control means 14 cancels the converter operation command to the converter control means 8 and stops the switching operation of the transistor 5 of the power factor improvement circuit 3. . At this time, the DC voltage VDC becomes V0, and the AC power supply 1
Is a value obtained by full-wave rectification by the full-wave rectification circuit 2.

In FIG. 9B, although the inverter control means 14 determines the motor output or the like, the input current value or input power of the power factor improvement circuit 3 is determined and controlled by the converter control means 8. Has the same effect.

By applying such a control device to a compressor driving device, a high efficiency compressor can be realized.
An operation with low vibration becomes possible, and a highly reliable air conditioner can be obtained.

As described above, according to the embodiment of the present invention, the input power of the power factor correction circuit, the DC power input to the inverter, the inverter output power output to the motor, or the inverter of the inverter. Since the DC voltage value of the smoothing circuit is changed stepwise according to either the duty or the motor output, the motor can be operated in a wide and efficient state from a high output to a low output. In addition, since the switching operation of the power factor correction circuit is stopped according to the operation state of the device, abnormal rise of the DC voltage can be prevented and high-efficiency operation can be performed.

Further, the output of the motor can be controlled to be constant without being affected by the DC voltage variable by the power factor correction circuit or by the ripple voltage of the power supply frequency superimposed on the DC voltage.

Further, by applying this electric motor driving device to a compressor of an air conditioner, high efficiency and low vibration operation as a compressor can be achieved, and a highly reliable air conditioner can be obtained.

[0054]

According to the first aspect of the present invention, the switching element of the power factor correction circuit is operated so as to change the DC voltage value of the smoothing circuit stepwise according to the output of the motor. Efficiency is improved, and high-efficiency operation of the device becomes possible.

According to the second aspect of the present invention, the switching element of the power factor correction circuit is operated so as to change the DC voltage value of the smoothing circuit stepwise according to the input power of the power factor correction circuit. In addition, the efficiency of the inverter and the motor is improved, and the device can be operated with high efficiency.

According to the third aspect of the present invention, the switching element of the power factor correction circuit is operated so as to change the DC voltage value of the smoothing circuit stepwise according to the DC power input to the inverter. In addition, the efficiency of the inverter and the motor is improved, and the device can be operated with high efficiency.

According to the fourth aspect , the switching element of the power factor correction circuit is operated so as to change the DC voltage value of the smoothing circuit stepwise according to the inverter output power output to the motor. As a result, the efficiency of the inverter and the motor is improved, and the device can be operated with high efficiency.

According to the fifth aspect of the invention, the efficiency of the inverter and the motor is increased while the speed of the motor is continuously controlled, and the device can be operated with high efficiency.

According to the sixth aspect of the invention, the ripple voltage of the smoothing circuit is corrected by the inverter to control the output of the motor so as not to pulsate, so that the vibration and noise of the motor can be reduced.
The reliability of the device is improved.

According to the seventh aspect , the abnormal voltage rise of the smoothing circuit due to the light load output of the power factor improving circuit can be prevented by the inverter circuit, so that the reliability of the device is improved and the DC voltage of the smoothing circuit is required. Since it is possible to prevent an increase in the loss of the inverter due to the above-mentioned high cost, the device can be operated efficiently.

According to the eighth aspect , even if the DC voltage of the smoothing circuit is changed by the power factor correction circuit, the output of the motor can be continuously varied at a constant or arbitrary value, and abnormal fluctuation of the output is suppressed. Operation is possible.

According to the ninth aspect, even when the DC voltage of the smoothing circuit is changed stepwise by the power factor improving circuit, the output of the motor can be continuously varied at a constant or arbitrary value and the output is abnormal. Operation that suppresses fluctuations becomes possible.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a motor control device according to an embodiment of the present invention.

FIG. 2 is a block diagram of an inverter control unit.

Fig. 3 DC voltage to motor output, inverter
FIG. 4 is a characteristic diagram showing duty and inverter output voltage.

FIG. 4 is a characteristic diagram showing the inverter output voltage with respect to the inverter duty, and the total efficiency of the inverter and the motor.

FIG. 5 is a characteristic diagram showing a temporal change of a DC voltage, an inverter output voltage, and an inverter duty.

FIG. 6 is a characteristic diagram showing a hysteresis of a DC voltage and an inverter duty when a motor output changes.

FIG. 7 is a waveform diagram showing a DC voltage on which a ripple voltage is superimposed, a DC voltage after control, and an inverter output voltage.

FIG. 8 is a view showing a flowchart for determining a DC voltage set value.

FIG. 9 is a diagram showing a flowchart for determining whether to stop switching operation of a transistor in the power factor correction circuit.

FIG. 10 is a circuit diagram showing a motor control device according to a conventional technique.

[Explanation of symbols]

1 AC power supply, 2 full-wave rectifier circuit, 3 power factor improvement circuit,
10 smoothing circuit, 12 inverter, 13 inverter drive circuit, 14 inverter control means, 15 electric motor.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hitoshi Kawaguchi 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Inside Mitsubishi Electric Corporation (72) Inventor Takahiro Motoki 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Inside Electric Co., Ltd. (72) Inventor Shoji Mochizuki 2-6-1, Otemachi, Chiyoda-ku, Tokyo Mitsubishi Electric Engineering Co., Ltd. (56) References JP-A-6-105563 (JP, A) JP-A-8- 33392 (JP, A) JP-A-9-149690 (JP, A) WO 97/13318 (WO, A1) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02P 5/408-5 / 412 H02P 7/628-7/632 H02P 21/00 H02M 7/42-7/98 F04B 49/00-51/00

Claims (9)

(57) [Claims] 1. A rectifier circuit and a smoothing circuit for converting AC power from an AC power supply to DC, a power factor improving circuit having a switching element and a reactor operating to improve a power factor, and a connection to the smoothing circuit. An inverter that outputs an arbitrary voltage and frequency, a motor connected to the inverter, and an inverter control unit that calculates an output of the motor based on a detected current value of a load current detector to control the speed of the motor. A control device for the motor, wherein the switching element of the power factor correction circuit is operated so as to change the DC voltage value of the smoothing circuit stepwise according to the motor output. 2. A rectifier circuit and a smoothing circuit for converting AC power from an AC power supply into a DC power, a switching element and a reactor operating to improve a power factor, and a detection current value of a power supply current detector. A power factor improving circuit for calculating input power, an inverter connected to the smoothing circuit and outputting an arbitrary voltage and frequency, a motor connected to the inverter, and inverter control means for controlling the speed of the motor. , According to the input power of the power factor correction circuit,
A control device for an electric motor, wherein a switching element of the power factor correction circuit is operated so as to change a DC voltage value of the smoothing circuit stepwise. 3. A rectifier circuit and a smoothing circuit for converting AC power from an AC power supply to DC, a power factor improving circuit having a switching element and a reactor operating to improve a power factor, and a connection to the smoothing circuit. An inverter that outputs an arbitrary voltage and frequency, a motor connected to the inverter, and an inverter control unit that calculates input power of the inverter based on a detected current value of a load current detector and speed-controls the motor. A control device for a motor, wherein the switching element of the power factor correction circuit is operated so as to change the DC voltage value of the smoothing circuit stepwise according to the input power of the inverter. 4. A rectifier circuit and a smoothing circuit for converting AC power from an AC power supply into a DC power, a power factor improving circuit having a switching element and a reactor operating to improve a power factor, and a connection to the smoothing circuit. An inverter that outputs an arbitrary voltage and frequency, a motor connected to the inverter, and an inverter control unit that calculates output power of the inverter based on a detected current value of a load current detector and speed-controls the motor. A control device for a motor, wherein the switching element of the power factor correction circuit is operated so as to change the DC voltage value of the smoothing circuit stepwise according to the output power of the inverter. 5. A method according to claim 1 or claims, characterized in that to continuously speed controlling said electric motor by the inverter
Item 5. The control device for an electric motor according to any one of Items 4 . 6. In accordance with a pulsating voltage of the smoothing circuit,
The motor control device according to any one of claims 1 to 5 , wherein a voltage applied to the motor is controlled by the inverter. 7. The switching element of the power factor correction circuit is stopped when any one of an input power of the inverter, an output of the motor, or an inverter duty of the inverter is equal to or less than a predetermined value. The control device for an electric motor according to claim 1 or 3 , wherein 8. A rectifier circuit and a smoothing circuit for converting AC power from an AC power supply to DC, a power factor improving circuit having a switching element and a reactor operating to improve a power factor, and a connection to the smoothing circuit. An inverter that outputs an arbitrary voltage and frequency, an electric motor connected to the inverter, and inverter control means for controlling the speed of the electric motor, wherein the inverter output voltage and the DC voltage of the smoothing circuit are changed by an arbitrary change rate. A control device for a motor, wherein a switching element of the inverter and the power factor correction circuit is controlled so as to be changed simultaneously. 9. The motor control device according to claim 8 , wherein a switching element of the power factor correction circuit is controlled so that a DC voltage of the smoothing circuit is varied stepwise.