JP2001238480A - Inverter device and electric washing machine using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To drive an electric motor by reliably detecting a back electromotive power waveform that is generated in an armature coil, even when the load of the electric motor is large. SOLUTION: A control means 8 for turning on or off switching means 3a-3f for constituting an inverter circuit 3, application voltage control means 9 for controlling the application voltage of armature coils 4a-4c, voltage detection means 5 for detecting the terminal voltage of the armature coils 4a-4c, comparison means 7 for comparing the output of the voltage detection means 5 with a reference voltage, and reference voltage-setting means 6 for setting a reference voltage are provided. Then, the electric motor 4 is controlled as a synchronous motor, at the same time, an application voltage control means 9 controls the application voltage of the armature coils 4a-4c for a fixed time when the electric motor 4 reaches a specific speed on activation, so that the control means 8 turns the switching means 3a-3f on or off, according to the output of the comparison means 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter for driving an electric motor having a rotor having a permanent magnet, and an electric washing machine having the inverter.

[0002]

2. Description of the Related Art FIG. 11 is a circuit diagram of a main part of a conventional inverter device. AC power supply 1 is connected to rectifier circuit 2,
The rectifier circuit 2 supplies DC power to the inverter circuit 3, and the output terminal of the inverter circuit 3 is connected to the electric motor 4.

The rectifier circuit 2 is configured as a voltage doubler rectifier circuit by a series circuit of a diode bridge 2a and two capacitors 2b and 2c for smoothing.

[0004] The inverter circuit 3 has a three-phase six-stone structure with switching means 3a, 3b and 3c on the high potential side and switching means 3d, 3e and 3f on the low potential side. The switching means 3a to 3f are constituted by a parallel circuit of an IGBT and a reverse connection diode capable of supporting high-frequency switching and large current capacity.

The electric motor 4 comprises a rotor having a permanent magnet 4d and a stator having a three-phase winding composed of three armature windings 4a to 4c.

The voltage detecting means 41 includes voltage dividing circuits 41a, 41b and 41c each comprising at least two resistors and a capacitor.
Are connected to the respective terminals of the armature windings 4a to 4c.

The reference voltage setting means 42 star-connects at least three resistors 42a, 42b and 42c having the same constant, and connects the other terminal of each resistor to the armature windings 4a to 4a.
4c, a virtual neutral fixed point circuit 42d connected to each terminal and a voltage dividing circuit 42e composed of at least two resistors and a capacitor for dividing the neutral point voltage of the virtual neutral point circuit 42d.

The comparing means 43 comprises three comparators 43a, 43b, 43c for comparing the output value of the voltage detecting means 41 with the output value of the reference voltage setting means 42, and outputs a high or low logic.

The control means 44 is composed of a microcomputer or a plurality of logic circuits.
3f is turned on / off in an electrical angle of 120 degrees.

The applied voltage control means 45 is provided in a microcomputer constituting the control means 44, and controls the energization ratio of the switching means 3a to 3f during the ON period to thereby control the armature windings 4a to 4c. The average value of the applied voltage is controlled. That is, the voltage applied to the electric motor 4 is controlled by pulse width modulation.

FIG. 12 shows a time chart of drive control of the electric motor 4. (A) shows the output frequency of the power output from the inverter circuit 3. (B) shows the armature windings 4a to 4a controlled by the applied voltage control means 45.
The average value of the applied voltage of c is shown.

The operation of the inverter device shown in FIG. 11 will be described with reference to FIG. When the operation of the electric motor 4 is started at t0, the switching means 3a and 3e are turned on by the applied voltage v0 during the period from t0 to t1, and power is supplied to the armature windings 4a and 4b. As a result, an N-pole or S-pole magnetic field is generated in the armature windings 4a and 4b, the S-pole and the N-pole of the permanent magnet 4d are attracted, and the relative position of the permanent magnet 4d with respect to the armature windings 4a to 4c. Is determined.

[0013] From time t1, the control means 44 controls the switching means 3a to drive the motor 4 as a synchronous motor.
To 3f are on / off controlled. At this time, the control means 44 controls the switching means 3a to 3f to turn on for a period of 120 electrical degrees. Thus, a rotating magnetic field proportional to the output frequency of the inverter circuit 3 is generated in the armature windings 4a to 4c, and the rotor is rotationally driven by an electromagnetic force generated between the armature windings 4a to 4c and the magnetic field of the permanent magnet 4d. During the period from t1 to t2, the control unit 44 switches the switching units 3a to 3a so that the output frequency of the inverter 3 increases.
control f. The applied voltage control means 45 includes the armature winding 4
The energization ratio of the switching means 3a to 3f is controlled so that the average value of the applied voltages of a to 4c increases.

At t2, the output frequency of the inverter 3 becomes the predetermined value f1. That is, when the motor 4 has not lost synchronization, the motor 4 is rotating at a speed proportional to the predetermined frequency f1. At this time, the armature windings 4a to 4c
The average value of the applied voltages is v6. From t2, the control unit 44 controls the switching units 3a to 3f to turn on and off according to the logic output from the comparison unit 43. The applied voltage control means 45 controls the energization ratio of the switching means 3a to 3f so that the average value of the applied voltage of the armature windings 4a to 4c increases. Therefore, the motor 4 is controlled as a brushless DC motor.

[0015]

As described above, in the conventional inverter device, when starting the motor,
Regardless of the output of the comparing means, the control means drives the motor as a synchronous motor, and then controls the switching means on / off according to the output of the comparing means,
The motor drives the motor as a brushless DC motor. In order to reliably operate the motor as a synchronous motor due to a large variation in the amount of the laundry to be washed, such as an electric washing machine, there is sufficient armature winding of the motor. Supplying a current, as a result, when the load is small, the current flowing through the armature winding with respect to the output of the voltage detection means has a large delay phase, and the voltage detection means is generated in the armature winding There is a problem that the back electromotive force cannot be detected, and the motor does not operate when the motor is controlled as a brushless DC motor. In addition, this subject had a tendency to become more remarkable as it became a copper machine.

The present invention solves the above-mentioned problems of the conventional inverter device. Even if the load changes every time the motor is started, the motor is started reliably, and thereafter the armature is reliably started. It is an object of the present invention to provide an inverter device that drives the electric motor based on a back electromotive force waveform generated in a winding, and an electric washing machine using the same.

[0017]

In order to achieve the above object, the present invention provides a motor having a permanent magnet in a rotor and an armature winding in a stator, an inverter circuit connected to the motor, and Control means for controlling on / off of switching means constituting an inverter circuit; applied voltage control means for controlling an applied voltage of the armature winding; voltage detection means for detecting a terminal voltage of the armature winding; Comparing means for comparing the output voltage of the voltage detecting means with a reference voltage, and reference voltage setting means for setting the reference voltage.At startup, the control means controls the motor as a synchronous motor and controls the speed of the motor. When the speed of the electric motor reaches a predetermined value, the applied voltage control means controls the applied voltage of the armature winding to a predetermined value for a certain period, and the control means Since the switching means is controlled in accordance with the output of the means, the current flowing in the armature winding when the control means controls the switching means by the output of the comparing means becomes small, The period during which the regenerative current flows through the winding is shortened, the period during which the back electromotive force waveform generated in the armature winding is output in the output waveform of the voltage detection unit is increased, and the comparison unit outputs the output of the voltage detection unit. It is possible to realize an inverter device with stable performance that can accurately compare the voltage with the output voltage of the reference voltage setting means.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention according to claim 1 of the present invention provides a motor having a permanent magnet in a rotor and an armature winding in a stator, an inverter circuit connected to the motor, and the inverter. Control means for controlling on / off of a switching means constituting a circuit; applied voltage control means for controlling an applied voltage of the armature winding; voltage detection means for detecting a terminal voltage of the armature winding; Comparing means for comparing the output voltage of the detecting means with a reference voltage, and reference voltage setting means for setting the reference voltage. At startup, the control means controls the motor as a synchronous motor and increases the speed of the motor. When the speed of the electric motor reaches a predetermined value, the applied voltage control means controls the applied voltage of the armature winding to a predetermined value for a certain period, and the control means outputs the output of the comparison means. Therefore, the current flowing through the armature winding when the control means controls the switching means based on the output of the comparison means becomes small, The period during which the regenerative current flows becomes shorter, the period during which the voltage detecting means can detect the back electromotive force waveform generated in the armature winding becomes longer, and the comparing means outputs the output voltage of the voltage detecting means and the reference voltage setting means. , Which can accurately compare the output voltages of the inverters.

According to a second aspect of the present invention, in the first aspect of the present invention, when the speed of the motor reaches a predetermined value, the control means changes the instantaneous value of the output frequency of the switching means. The switching means is controlled in accordance with the output of the comparing means, so that when the control means drives the motor as a synchronous motor, a current flowing in the armature winding causes a counter electromotive force to be generated in the armature winding. The state in which the phase is delayed with respect to the power waveform is corrected, and the comparing means can accurately compare the output value of the voltage detecting means with the output voltage of the reference voltage setting means.

According to a third aspect of the present invention, in the first aspect of the present invention, when the speed of the motor reaches a predetermined value, the control means turns off all the switching means.
Thereafter, since the switching means is controlled to be turned on and off in accordance with the output of the comparing means, when the control means controls the switching means in accordance with the output of the comparing means,
Once there is no current flowing through the armature winding, back electromotive force generated in the armature winding can be detected. Therefore, it is possible to realize an inverter device with stable performance capable of reliably driving the electric motor.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the applied voltage control means includes a first set value of an applied voltage of the armature winding and the first set value of the applied voltage. It has a second set value that is smaller than the first set value and a third set value that is smaller than the second set value, and when the electric motor is driven to rotate as a synchronous motor, the applied voltage control means takes time. When the applied voltage of the armature winding is increased in proportion to the first set value, and the speed of the motor becomes a predetermined value,
The applied voltage control means controls the applied voltage of the armature winding to the third set value for a certain period of time, and the control means controls the switching means according to the output of the comparison means. Since the value is increased from the second set value, when the control means controls the switching means according to the output of the comparison means, it is possible to prevent the speed of the motor from being rapidly accelerated or decelerated. .

According to a fifth aspect of the present invention, since the inverter device according to any one of the first to fourth aspects is provided, the amount of the laundry to be washed in the electric washing machine fluctuates and the load on the electric motor is changed. The control means can reliably control the switching means in accordance with the output of the comparing means even if the phase difference changes and the phase difference between the current flowing through the armature winding and the back electromotive force waveform generated in the armature winding fluctuates. A stable electric washing machine can be realized.

According to a sixth aspect of the present invention, in accordance with the fifth aspect of the present invention, there is provided a cloth amount detecting means for detecting an amount of the laundry, and the applied voltage control means is provided when the motor is started. Since the voltage applied to the armature winding is controlled in accordance with the output of the cloth amount detecting means, even when the amount of the laundry changes, the synchronization is lost when the motor is driven as a synchronous motor. Can be prevented.

[0024]

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

(Embodiment 1) FIG. 1 is a circuit block diagram of a main part of an inverter device according to Embodiment 1. Reference numeral 1 denotes an AC power supply to which a rectifier circuit 2 is connected.

The rectifier circuit 2 is configured as a voltage doubler rectifier circuit by a series circuit of a diode bridge 2a and two electrolytic capacitors 2b and 2c for smoothing, and supplies DC power to the inverter circuit 3.

The inverter circuit 3 has a three-phase six-stone configuration with three high-potential-side switching means 3a, 3b, and 3c and three low-potential-side switching means 3d, 3e, and 3f. Supply phase full-wave AC power. In this embodiment, the switching means 3a to 3f are IG
It is composed of a parallel circuit of BT and reverse connection diode. However, the switching means 3a to 3f are not limited to this, and may be, for example, a parallel circuit of a semiconductor switching element such as a transistor, a MOSFET, and a triac and a reverse connection diode.

The motor 4 is composed of a rotor and a stator.
The stator has armature windings 4a, 4b and 4c, and the armature windings 4a to 4c are star-connected to form a three-phase winding. The stator has an iron core having a configuration of 12 slots, and the armature windings 4a to 4c are concentratedly wound. The rotor has an eight-pole permanent magnet 4d. Although not shown in the present embodiment, the electric motor 4 has an inner rotor configuration. However, the present invention is not particularly limited to this, and an outer rotor may be used. Also, the number of poles of the permanent magnet 4d and the number of slots of the stator are not particularly limited.

The voltage detecting means 5 detects the voltage of each terminal of the armature windings 4a to 4c. In this embodiment, the voltage dividing circuits 5a, 5b and 5c are provided for each terminal. Each of the voltage dividing circuits 5a to 5c includes at least two resistors and a capacitor.

The reference voltage setting means 6 comprises a virtual neutral point circuit 6d in which at least three resistors 6a, 6b and 6c are star-connected, and a voltage dividing circuit 6e for dividing the neutral point voltages of the resistors 6a to 6c. You. The other terminals of the resistors 6a to 6c are connected to the respective terminals of the armature windings 4a to 4c. The resistors 6a to 6c have the same constant. The configuration of the reference voltage setting means 6 is not limited to this.
For example, the output voltage of the rectifier circuit 2 may be reduced to 1/2, or the output terminals of the voltage divider circuits 5a to 5c may be connected to a star-connected circuit with at least three resistors, and the neutral point voltage of this circuit may be reduced. The reference voltage may be used, or the armature windings 4a to
A voltage obtained by dividing the neutral point voltage of 4c may be used as the reference voltage.

The comparing means 7 comprises three comparators 7a to 7
c, and compares the output voltage of each of the voltage dividing circuits 5a to 5c with the output voltage of the reference voltage setting means 6, and outputs high or low. However, the configuration of the comparing means 7 is as follows.
It is not limited to this. For example, the comparator 7
a to 7c may be operational amplifiers or voltage dividing circuits 5a to 5c.
After AD conversion of 5c and the output voltage of the reference voltage setting means 6, this value may be compared by a magnitude comparator.

As described above, the voltage detecting means 5, the reference voltage setting means 6, and the comparing means 7 change the magnetic flux linked to the armature windings 4a to 4c by rotating the permanent magnet 4d constituting the rotor. Thus, the relative position of the permanent magnet 4d with respect to the armature windings 4a to 4c may be detected using the back electromotive force generated in the armature windings 4a to 4c. It is not limited to the configuration.

The control means 8 comprises a microcomputer and a plurality of logic circuits. The filter means 8a removes unnecessary components of the output signals of the comparators 7a to 7c, and is realized by arithmetic processing inside the microcomputer. The control means 8 controls on / off of the switching means 3a to 3f according to the combination of the logic of the signals. In this embodiment, the on / off states of the switching means 3a to 3f corresponding to the combination of the logic of the signal obtained by filtering the output of the comparing means 7 are stored in advance in a memory in the microcomputer as a table. In a device such as the electric washing machine according to the present invention, in which the rotation direction of the electric motor 4 is normal or reverse, the order of the logic output by the comparison means 7 changes for each rotation direction. Good. However, this table is an example, and the present invention is not limited to this.

The applied voltage control means 9 is provided in a microcomputer constituting the control means 8, and controls the energization ratio of the switching means 3a to 3f during the ON period to thereby control the armature windings 4a to 4c. The average value of the applied voltage is controlled. That is, the voltage applied to the electric motor 4 is controlled by pulse width modulation. In addition, the control method of the applied voltage of the armature windings 4a to 4c is not limited to this.
For example, the DC voltage output from the rectifier circuit 2 may be controlled by configuring the rectifier circuit 2 as a booster circuit, a step-down circuit, or a step-up / step-down circuit.

The drive circuit 10 has a push-pull circuit configuration using, for example, an NPN transistor and a PNP transistor. When the drive circuit 10 is on, one is connected to the gate terminal of the IGBT.
A power of 5 V is supplied, and when the power is off, the voltage of the gate terminal is set to 0 V.

FIG. 2 shows a flowchart when the electric motor 4 of the inverter device of FIG. 1 is driven to rotate.

The operation of the inverter device according to this embodiment will be described with reference to FIGS.

When the operation of the inverter starts, the start control is performed in block 11. In this startup control, the control means 8 turns on the switching means 3a, 3e, and the applied voltage control means 9 sets the switching means 3a, 3e so that the applied voltage of the armature windings 4a to 4c becomes a predetermined value.
To supply power to the armature windings 4a and 4b. As a result, the armature windings 4a, 4b have N poles or S poles.
A pole magnetic field is generated, and the S and N poles of the permanent magnet 4d are attracted, so that the relative position of the permanent magnet 4d with respect to the stator is determined.

In the synchronous motor control of the block 12, the control means 8 controls the switching means 3a to 3f to turn on and off in order to drive the motor 4 as a synchronous motor. At this time, the control means 8 controls the switching means 3a to 3f to be turned on only during a period of 120 electrical degrees. As a result, a rotating magnetic field proportional to the output frequency of the inverter circuit 3 is generated in the armature windings 4a to 4c, and drives the rotor to rotate. Thereafter, the control means 8 controls the switching means 3a to 3f so that the output frequency of the inverter circuit 3 increases. The applied voltage control means 9 controls the energization ratio of the switching means 3a to 3f so that the average value of the applied voltages to the armature windings 4a to 4c increases.

In the switching control of the block 13, the applied voltage control means 9 controls the energization ratio of the switching means 3a to 3f so that the average value of the applied voltage to the armature windings 4a to 4c becomes small. At this time, the control means 8 controls on / off of the switching means 3a to 3f so that the output frequency of the inverter circuit 3 becomes the same as that in the synchronous motor control 12.

In the brushless DC motor control of the block 14, the control means 8 controls the switching means 3a to 3f on and off according to the output of the comparison means 7.

As described above, by providing the switching control 13 between the synchronous motor control 12 and the brushless DC motor control 14, the brushless D
It is possible to prevent the operation of the electric motor 4 from being stopped when changing to driving as the C motor.

As another example, in FIGS. 4, 6, 8 and 9, which will be described later, the start control 11 is performed at t0 to t1.
, The synchronous motor control 12 corresponds to the period from t1 to t2, the switching control 13 corresponds to the period from t2 to t3, and the brushless DC motor control 14 corresponds to the period.

FIG. 3 is a block diagram of a main part of an electric washing machine using the inverter device of FIG. 1, and shows an embodiment of the electric washing machine according to claim 5 of the present invention. As shown in FIG. 3, the water receiving tub 21 is provided with a washing and dewatering tub 23 in which an agitating blade 22 is rotatably provided on an inner bottom portion, and is suspended from a washing machine main body 25 by a suspension 24.
The speed reduction mechanism 26 is provided at the bottom of the water receiving tank 21,
The motor 4 is provided below the speed reduction mechanism 26 for transmitting power to the washing and dewatering tub 23. The water supply valve 27 is for supplying water to the washing and dewatering tub 23, and the drainage valve 28 is for draining washing water and the like in the washing and dewatering tub 23. The control board 29 of the electric motor 4 includes, in addition to the circuit shown in FIG. 1, a drive circuit for the water supply valve 27 and the drain valve 28, an operation display unit for a user to operate, and the like.

The speed reduction mechanism 26 has a planetary gear. When the stirring blade 22 is driven to rotate, the sun gear is driven by the output shaft of the electric motor 4 and the rotation of the planetary gear is transmitted to the stirring blade 22. , And reduces the output torque of the electric motor 4 to 6 times. In the case of rotating the washing and dewatering tub 23 such as dehydrating, although not particularly shown, the speed reduction mechanism 26 is separated from the output shaft of the electric motor 4 by a clutch mechanism, and the washing and dewatering tub 23 is directly driven by the electric motor 4.
However, the present invention is not particularly limited to such a configuration of the electric motor. For example, a configuration in which the power of the electric motor 4 is transmitted to the reduction mechanism 26 by a belt or the electric motor 4 without the reduction mechanism 26 is provided.
May be directly transmitted to the stirring blade 22.

As described above, in the electric washing machine of this embodiment,
Since it is not necessary to provide the motor 4 with a position detecting means constituted by a Hall IC or the like, there is no need to connect the position detecting means and the control board 29 by wiring, and wiring costs and the like are eliminated, thereby reducing costs. it can. In addition, since it is not necessary to provide a location for installing the position detecting means, the motor 4
Can be reduced in size, and as a result, the height of the electric washing machine can be reduced.

FIG. 4 shows an example of a time chart of the drive control of the electric motor 4 when the washing and dewatering tub is rotated in FIG. (A) shows the output frequency of the inverter circuit 3 that outputs to the electric motor 4. (B) shows the average value of the applied voltage of the armature windings 4 a to 4 c controlled by the applied voltage control means 9.

When the operation of the motor 4 is started at t0, the switching means 3a and 3e are turned on by the applied voltage v0 during the period from t0 to t1, and power is supplied to the armature windings 4a and 4b. As a result, an N-pole or S-pole magnetic field is generated in the armature windings 4a, 4b, the S-pole and the N-pole of the permanent magnet 4d are attracted, and the relative position of the permanent magnet 4d with respect to the stator is determined.

After t1, the control means 8 switches the switching means 3a to 3a to drive the motor 4 as a synchronous motor.
3f is turned on / off. At this time, the control means 8 controls the switching means 3a to 3f to be turned on only during a period of 120 electrical degrees. As a result, a rotating magnetic field proportional to the output frequency of the inverter circuit 3 is generated in the armature windings 4a to 4c, and drives the rotor to rotate.
During the period from t1 to t2, the control means 8 controls the switching means 3a to 3f so that the output frequency of the inverter circuit 3 increases. The applied voltage control means 9 controls the energization ratio of the switching means 3a to 3f so that the average value of the applied voltages to the armature windings 4a to 4c increases.

At t2, the output frequency of the inverter circuit 3 becomes the predetermined value f1. That is, when the motor 4 has not lost synchronization, the motor 4 is rotating at a speed proportional to the predetermined frequency f1. The applied voltage control means 9 controls the energization ratio of the switching means 3a to 3f so that the average value of the applied voltages of the armature windings 4a to 4c becomes v1.
At this time, the control means 8 controls the switching means 3a to 3f so that the output frequency of the inverter circuit 3 becomes the predetermined value f1.
On / off control. In the present embodiment, the period from t2 to t3 is a period of 360 electrical degrees. When the washing and dewatering tub 23 is driven as in this embodiment, the mass of the washing and dewatering tub 23 is large and its diameter is large. The rotation is maintained for a while. Therefore, as shown in FIG. 3, the applied voltage control means 9 controls the average value of the applied voltages of the armature windings 4a to 4c to be small, and
Even if the current flowing through the a-c becomes small, the motor 4 continues to rotate at substantially the same speed as the speed at the time t2 due to the inertial force of the washing and dewatering tub 23. The output of the back electromotive force waveform near zero voltage is reliably detected, and the comparison means 7 can output accurate logic to the control means 8.

After t3, the control means 8 switches the switching means 3a in accordance with the logic output from the comparing means 7 at t2.
To 3f are on / off controlled. The applied voltage control means 9 controls the energization ratio of the switching means 3a to 3f so that the average value of the applied voltages to the armature windings 4a to 4c increases.
Therefore, the electric motor 4 is driven as a brushless DC motor.

FIG. 5 shows the armature windings 4a to 4c around t2.
3 shows voltage waveforms at each terminal. (A) is a terminal voltage waveform of the armature winding 4a, (b) is a terminal voltage waveform of the armature winding 4b, (c) is a terminal voltage waveform of the armature winding 4c,
(D) shows the current waveform of the armature winding 4a, (e) shows the current waveform of the armature winding 4b, and (f) shows the current waveform of the armature winding 4c. Although not shown in FIG. 5, each of the switching means 3a to 3f is turned on only during the period of 120 electrical degrees.

As shown in FIG. 5, when the motor 4 is driven as a synchronous motor before t2, the currents in the armature windings 4a to 4c are changed with respect to the back electromotive force waveform in order to prevent loss of synchronization. The switching means 3a to 3d
Since 3f is on / off controlled, the current is larger than when driven as a brushless DC motor, the period during which the regenerative current flows is longer, and the period during which the back electromotive force waveform generated in the armature windings 4a to 4c can be detected is shorter. Become. However, after t2, the applied voltage control means 9 sets the armature winding 4a
4c so that the average value of the applied voltages becomes a predetermined value v0.
Since the duty ratio of the switching means 3a to 3f is reduced, the current flowing through the armature windings 4a to 4c becomes small, and the period during which the regenerative current flows becomes short. Therefore, the armature winding 4
Since the period during which the back electromotive force waveforms a to 4c can be detected becomes longer, the voltage detecting means 5 can surely detect the phase of the back electromotive force of the armature windings 4a to 4c near zero voltage. The means 7 can output accurate logic to the control means 8.

As described above, when the control means 8 controls the switching means 3a to 3f according to the output of the comparison means 7, the applied voltage control means 9 sets the average value of the applied voltages of the armature windings 4a to 4c. , It is possible to reliably switch the control of the motor 4 from a control as a synchronous motor to a control as a brushless DC motor. Therefore, it is possible to realize a highly reliable inverter device that can reliably drive the electric motor 4 to the target speed and an electric washing machine using the inverter device.

(Embodiment 2) FIG. 6 shows a washing and dewatering tub 23 of an electric washing machine using an inverter device according to Embodiment 2 of the present invention.
4 shows a time chart of drive control of the electric motor 4 when the motor is driven to rotate. Therefore, this electric washing machine corresponds to an embodiment of claim 5. Other configurations are shown in FIGS.
Is the same as

(A) shows the output frequency of the inverter circuit 3 that outputs to the motor 4. (B) shows the average value of the voltage applied to the armature windings 4a to 4c controlled by the applied voltage control means 9.

This will be described with reference to FIG. At t0, the electric motor 4
Is started, the switching means 3a and 3e are turned on with a predetermined applied voltage v0 during the period from t0 to t1, and the armature windings 4a and 4b are energized. As a result, an N-pole or S-pole magnetic field is generated in the armature windings 4a, 4b, the S-pole and the N-pole of the permanent magnet 4d are attracted, and the relative position of the permanent magnet 4d with respect to the stator is determined.

After t1, the control means 8 switches the switching means 3a to 3d in order to drive the motor 4 as a synchronous motor.
3f is turned on / off. At this time, the control means 8 controls the switching means 3a to 3f to be turned on only during a period of 120 electrical degrees. As a result, a rotating magnetic field proportional to the output frequency of the inverter circuit 3 is generated in the armature windings 4a to 4c, and drives the rotor to rotate.
During the period from t1 to t2, the control unit 8 controls the switching units 3a to 3f to turn on and off so that the output frequency of the inverter circuit 3 increases. Applied voltage control means 9
Controls the energization ratio of the switching means 3a to 3f during the ON period so that the average value of the applied voltages to the armature windings 4a to 4c increases.

At t2, the output frequency of the inverter circuit 3 becomes the predetermined value f1. That is, when the motor 4 has not lost synchronization, the motor 4 is rotating at a speed proportional to the predetermined frequency f1. The applied voltage control means 9 controls the energization ratio of the switching means 3a to 3f so that the average value of the applied voltages of the armature windings 4a to 4c becomes a predetermined value v2. The control unit 8 shortens only the ON period of one of the switching units 3a to 3f. That is, at t2, the output frequency of the inverter circuit 3 is set to the frequency f2 higher than the predetermined frequency f1. In this embodiment, the switching means 3a to 3f are turned on / off at the predetermined frequency f1 during the subsequent electrical angle of 360 degrees so as to reach t3.

When the washing and dewatering tub 23 is driven as in this embodiment, the mass of the washing and dewatering tub 23 is large and the diameter thereof is large. It keeps rotating for a while by force. Therefore, as shown in FIG. 5, the applied voltage control means 9 reduces the energization ratio of the switching means 3a to 3c so as to reduce the average value of the applied voltage to the armature windings 4a to 4c. Even if the current flowing through to 4c is reduced, the motor 4 continues to rotate at substantially the same speed as the speed at the time t2 due to the inertia of the washing and dewatering tub 23. In the present embodiment, since the control means 8 makes the on / off switching of the switching means 3a to 3f quicker, the current flowing through the armature windings 4a to 4c and the armature winding when the motor 4 is being driven as a synchronous motor. The phase difference generated between the back electromotive forces generated in the lines 4a to 4c can be reduced. As a result, the comparing means 7 outputs the armature windings 4 a to 4 a output from the voltage detecting means 5.
The counter electromotive force waveform of c and the output of the reference voltage setting means 6 can be reliably detected, and accurate logic can be output to the control means 8.

After t3, the control means 8 switches the switching means 3a in accordance with the logic output from the comparison means 7 at t2.
To 3f are on / off controlled. The applied voltage control means 9 controls the energization ratio of the switching means 3a to 3f so that the average value of the applied voltages to the armature windings 4a to 4c increases.
That is, the motor 4 is controlled as a brushless DC motor.

FIG. 7 shows the armature windings 4a to 4c around t2.
3 shows voltage waveforms at each terminal. (A) is a terminal voltage waveform of the armature winding 4a, (b) is a terminal voltage waveform of the armature winding 4b, (c) is a terminal voltage waveform of the armature winding 4c,
(D) shows the current waveform of the armature winding 4a, (e) shows the current waveform of the armature winding 4b, and (f) shows the current waveform of the armature winding 4c.

As shown in FIG. 7, when the motor 4 is driven as a synchronous motor before t2, the current flowing through the armature windings 4a to 4c changes with respect to the back electromotive force waveform to prevent loss of synchronization. Since the phase is delayed, the current becomes larger than when the motor 4 is driven as a brushless DC motor, and the period during which the regenerative current flows becomes longer,
The period in which the back electromotive force waveform generated in the armature windings 4a to 4c can be detected is shortened. However, at t2, the on / off switching of the switching means 3a to 3f is advanced only once, so that the lag phase with respect to the back electromotive force waveform of the current flowing through the armature windings 4a to 4c can be instantaneously corrected. At the same time, the applied voltage control means 9 makes the armature windings 4a to 4c
So that the average value of the voltage applied to
Since the duty ratio of the switching means 3a to 3f is reduced, the current flowing through the armature windings 4a to 4c is reduced, and the period during which the regenerative current flows through the reverse-connected diode is shortened. Therefore, the phase difference between the back electromotive force waveforms generated in the armature windings 4a to 4c and the on / off waveforms of the switching means 3a to 3f becomes small, and the vicinity of zero voltage of the back electromotive force waveform generated in the armature windings 4a to 4c is reduced. Since the voltage detecting means 5 can surely detect the phase, the comparing means 7 can reliably compare the output voltage of the reference voltage setting means 6 with the output voltage of the voltage detecting means 5.

(Embodiment 3) FIG. 8 is a time chart of drive control of the electric motor 4 when the washing and dewatering tub 23 of the electric washing machine using the inverter apparatus according to the third embodiment of the present invention is rotationally driven. I have. Therefore, this embodiment also corresponds to an embodiment of the electric washing machine described in claim 5. Other configurations are the same as those in FIGS.

(A) shows the output frequency of the inverter circuit 3 that outputs to the electric motor 4. (B) shows the average value of the applied voltage of the armature windings 4 a to 4 c controlled by the applied voltage control means 9.

This will be described with reference to FIG. At t0, the electric motor 4
Is started, the switching means 3a and 3e are turned on at a predetermined applied voltage v0 during the period from t0 to t1, and power is supplied to the armature windings 4a and 4b. As a result, an N-pole or S-pole magnetic field is generated in the armature windings 4a, 4b, the S-pole and the N-pole of the permanent magnet 4d are attracted, and the relative position of the permanent magnet 4d with respect to the stator is determined.

From time t1, the control means 8 controls the switching means 3a to 3f to turn on and off to control the armature windings 4a to 4c.
, A rotating magnetic field is generated, and the motor 4 is rotationally driven as a synchronous motor. At this time, the control means 8 controls the output frequency of the inverter circuit 3 to increase. At the same time, the applied voltage control means 9 controls the energization ratio of the switching means 3a to 3f so that the average value of the applied voltage to the armature windings 4a to 4c increases.

At t2, the output frequency of the inverter circuit 3 becomes the predetermined value f1. That is, when the motor 4 is not out of synchronization, the motor 4 is rotating at a speed proportional to the predetermined frequency f1. The control means 8 turns off all the switching means 3a to 3f. Therefore, the output frequency of the inverter circuit 3 becomes zero. In the case of a load that continues to rotate by inertia for a while after being rotated to some extent, such as the washing and dewatering tub 23 of the electric washing machine shown in the present embodiment, even if all the switching means 3a to 3f are turned off, The motor 4 rotates at substantially the same speed as the speed of the motor 4. Therefore, the output waveform of the voltage detecting means 5 is
In this case, only the back electromotive force waveforms a to 4c are obtained, and the comparison means 7 can reliably compare the output value of the voltage detection means 5 and the output value of the reference voltage setting means 6 with a phase near zero voltage of the back electromotive force. it can.

After t3, the control means 8 controls the switching means 3a to 3f to turn on and off in accordance with the output of the comparison means 7, and drives the motor 4 to rotate to the final target rotation speed.

As described above, when the control means 8 controls on / off of the switching means 3a to 3f in accordance with the output of the comparison means 7, the control means 8 controls the switching means 3a to 3f.
Are all turned off, the current flowing through the armature windings 4a to 4c is eliminated, and the back electromotive force waveform generated in the armature windings 4a to 4c can be detected by the voltage detection means 5, so that the output logic of the comparison means 7 can be accurately determined. Thus, the reliability of the electric motor 4 can be improved.

(Embodiment 4) FIG. 9 is a time chart from the start of the washing and dewatering tub 23 of the electric washing machine using the inverter device according to the fourth embodiment to the target speed.
(A) shows the output frequency of the inverter circuit 3 controlled by the control means 8. (B) shows the average value of the applied voltage of the armature windings 4 a to 4 c controlled by the applied voltage control means 9. Other configurations are the same as those in FIGS.

This will be described with reference to FIG. At t0, the electric motor 4
Is started, the switching means 3a and 3e are turned on with a predetermined applied voltage v0 during the period from t0 to t1, and the armature windings 4a and 4b are energized. As a result, an N-pole or S-pole magnetic field is generated in the armature windings 4a, 4b, the S-pole and the N-pole of the permanent magnet 4d are attracted, and the relative position of the permanent magnet 4d with respect to the stator is determined.

From t1, the control means 8 switches the switching means 3a to 3d in order to drive the motor 4 as a synchronous motor.
3f is turned on / off. At this time, the control means 8 controls the switching means 3a to 3f to be turned on only during a period of 120 electrical degrees. As a result, a rotating magnetic field proportional to the output frequency of the inverter circuit 3 is generated in the armature windings 4a to 4c, and drives the rotor to rotate.
During the period from t1 to t2, the control unit 8 controls the switching units 3a to 3f to turn on and off such that the output frequency of the inverter circuit 3 increases in proportion to time. The applied voltage control means 9 determines that the average value of the applied voltages of the armature windings 4a to 4c is equal to the first set value v3 in proportion to the elapsed time from t1.
The energization ratio during the on-periods of the switching means 3a to 3f is controlled so as to increase the power supply ratio. In the present embodiment, the rate of increase of the average value of the applied voltages to the armature windings 4a to 4c is (v3-v
0) / (t2-t1). However, this is only an example, and it is not necessary to increase the average value of the applied voltage in proportion to time, and may be increased in a stepwise manner or may be fixed at a constant value.

At t2, the output frequency of the inverter circuit 3 becomes the predetermined value f1. That is, when the motor 4 has not lost synchronization, the motor 4 is rotating at a speed proportional to the predetermined frequency f1. The applied voltage control means 9 determines that the average value of the applied voltages of the armature windings 4a to 4c is the third set value v
The energization ratio of the switching means 3a to 3f is controlled so as to be 5. In this embodiment, the control means 8 has an electrical angle of 360
Switching means 3a-3 at a predetermined frequency f1
On / off control of f is performed so as to reach t3.

When the washing and dewatering tub 23 is driven as in this embodiment, the mass of the washing and dewatering tub 23 is large and its diameter is large. It keeps rotating for a while by force. Therefore, as shown in FIG. 9, the applied voltage control means 9 reduces the energization ratio of the switching means 3a to 3c so as to reduce the average value of the applied voltage to the armature windings 4a to 4c. Since the electric motor 4 continues to rotate at substantially the same speed as the speed at time t2 due to the inertial force of the washing and dewatering tub 23, the voltage detecting means 5 The back electromotive force waveform is reliably detected, and the comparing means 7 can accurately compare the output value of the voltage detecting means 5 with the output of the reference voltage setting means 6.

After t3, the control means 8 controls the switching means 3a to 3f to turn on and off according to the logic output from the comparing means 7. The applied voltage control means 9 includes armature windings 4a to
The energization ratio of the switching means 3a to 3f is controlled so that the average value of the applied voltage of 4c becomes the second set value v4, from which the average value of the applied voltage of the armature windings 4a to 4c increases. Then, the energization ratio of the switching means 3a to 3f is controlled. Therefore, after t3, the motor 4 is in the brushless DC
It is controlled as a motor.

When the motor 4 is controlled as a brushless DC motor, the lag phase of the armature winding current that occurred when the motor 4 was controlled as a synchronous motor is reduced. Armature winding 4
When the average value of the applied voltages a to 4c is controlled to be the first set value v3, the speed of the electric motor 4 rapidly rises, and when the electric motor 4 is used in the electric washing machine of this embodiment, the noise is reduced. Is instantaneously large. However, at t3, since the applied voltage controlled by the applied voltage control means 9 is set to the small second set value v4, sudden acceleration of the electric motor 4 can be prevented.

Further, the second set value v4 is changed to the third set value v
If it is smaller than 5, sufficient electric power is not supplied to the electric motor 4,
Since the speed of the motor 4 is reduced and the back electromotive force generated in the armature windings 4a to 4c is reduced, the voltage detection means 5 cannot accurately detect the back electromotive force waveform, and the motor 4 can be controlled as a brushless DC motor. However, in the present embodiment, the second set value v4 is set to be larger than the third set value v5, so that deceleration and operation stop of the electric motor 4 can be prevented.

(Embodiment 5) FIG. 10 shows a sixth embodiment of the present invention.
15 shows an electric washing machine according to a fifth embodiment of the present invention. The amount-of-cloth detecting means 31 detects the amount of the laundry to be put in the washing / dewatering tub 23, and outputs the result to the applied voltage control means 35. In the present embodiment, it is constituted by a current detecting means 32 for detecting the current of the armature windings 4a to 4c and a storage means 33 constituted by a memory in the microcomputer. The current detecting means 32 includes a current detecting resistor 32a and a current detecting resistor 3 connected to the negative potential side between the rectifier circuit 2 and the inverter circuit 3.
It comprises an amplifier circuit 32b for amplifying the output of 2a. The storage unit 33 stores in advance a table of the amount of laundry to be output with respect to the output of the current detection unit 32. Note that the cloth amount detecting means 31 is not limited to this. For example, a determination may be made by providing a weight sensor on the suspension 24 constituting the electric washing machine in FIG. 3 and detecting the force applied thereto. The control means 34 includes switching means 3a to 3f
The motor 4 is controlled as a synchronous motor at the time of start-up.
The electric motor 4 is controlled as a brushless DC motor by controlling on / off of the switching means 3a to 3f according to the output of the motor. The applied voltage control unit 35 controls the energization ratio during the ON period of the switching units 3a to 3f,
The average value of the applied voltages to the armature windings 4a to 4c is controlled. The applied voltage control means 35 sets an average value of applied voltages to the armature windings 4a to 4c when the electric motor 4 is started according to the output of the cloth amount detecting means 31. This value is the cloth amount detecting means 31
Are set so that the larger the amount of the laundry to be detected, the larger the amount.

The other structures are the same as those shown in FIGS.

As described above, the cloth amount detecting means 31 is provided,
An armature winding 4a during which the electric motor 4 is controlled as a synchronous motor in accordance with the amount of the laundry to be detected by the cloth amount detecting means 31.
Since the applied voltage control means 35 controls the average value of the applied voltages of ~ 4c, the electric motor 4 can be rotationally driven with the applied voltage optimum for the load. Therefore, when the electric motor 4 is driven as a synchronous motor, Noise can be further reduced. In addition, since synchronization can be prevented from being lost, an electric washing machine with stable performance can be realized.

[0082]

As described above, according to the first aspect of the present invention, a motor having a permanent magnet in a rotor and an armature winding in a stator, and an inverter connected to the motor. Control means for controlling on / off of a switching means constituting a circuit and the inverter circuit; applied voltage control means for controlling an applied voltage of the armature winding; and voltage detection means for detecting a terminal voltage of the armature winding. And a comparing means for comparing the output voltage of the voltage detecting means with a reference voltage, and a reference voltage setting means for setting the reference voltage. At the time of starting, the control means controls the motor as a synchronous motor and the motor When the speed of the electric motor reaches a predetermined value, the applied voltage control means controls the applied voltage of the armature winding to a predetermined value for a certain period, and the control means Since the switching means is controlled in accordance with the output of the comparing means, when the control means controls the switching means by the output of the comparing means, the current flowing through the armature winding becomes small, The period during which the regenerative current flows through the winding is shortened, the period during which the voltage detecting means can detect the back electromotive force waveform generated in the armature winding becomes longer, and the comparing means compares the output voltage of the voltage detecting means with the reference voltage. An inverter device with stable performance that can accurately compare the output voltages of the voltage setting means can be realized.

According to the second aspect of the present invention,
In the invention described in claim 1, the control means includes:
When the speed of the electric motor reaches a predetermined value, the instantaneous value of the output frequency of the switching means is changed, and then the switching means is controlled in accordance with the output of the comparing means, so that the control means synchronizes the electric motor. Even if the current flowing through the armature winding when driving as an electric motor has a large lag phase with respect to the back electromotive force waveform generated in the armature winding, this state is corrected, and the voltage detection means The vicinity of zero voltage of the back electromotive force waveform can be detected,
The comparing means can accurately detect the position of the permanent magnet by comparing the output value of the voltage detecting means with the output voltage of the reference voltage setting means. Therefore, an inverter device that can reliably drive the electric motor can be realized.

According to the third aspect of the present invention,
In the invention described in claim 1, the control means includes:
When the speed of the electric motor reaches a predetermined value, all of the switching means are turned off, and then the switching means is controlled to be turned on and off in accordance with the output of the comparing means. When controlling the switching means, once the current flowing in the armature winding disappears, the back electromotive force generated in the armature winding can be detected. Therefore, it is possible to realize an inverter device with stable performance capable of reliably driving the electric motor.

According to the invention described in claim 4 of the present invention,
The invention according to any one of claims 1 to 3, wherein the applied voltage control means includes a first set value of an applied voltage of the armature winding and a second set value smaller than the first set value. A value and a third set value that is smaller than the second set value,
When the motor is rotationally driven as a synchronous motor, the applied voltage control means increases the applied voltage of the armature winding up to the first set value in proportion to time, and when the speed of the motor reaches a predetermined value, The applied voltage control means
When the applied voltage of the armature winding is controlled to the third set value, and the control means controls the switching means according to the output of the comparing means, the applied voltage control means sets the second set value. Since the control unit controls the switching unit in accordance with the output of the comparison unit, it is possible to prevent the speed of the electric motor from being rapidly accelerated or decelerated.

According to the fifth aspect of the present invention,
Since the inverter device according to any one of claims 1 to 4 is provided, an amount of the laundry to be washed of the electric washing machine fluctuates, and a load of the electric motor changes. Even if the phase difference of the back electromotive force waveform generated in the armature winding fluctuates, the back electromotive force waveform can be reliably detected by the voltage detection means, and the control means controls the switching means in response to the output of the comparison means. And a stable electric washing machine with a controllable performance.

According to the sixth aspect of the present invention,
The invention according to claim 5, further comprising a cloth amount detecting unit for detecting an amount of the laundry, wherein the applied voltage control unit is configured to start the electric motor in response to an output of the cloth amount detecting unit. Since the voltage applied to the armature winding is controlled, it is possible to prevent loss of synchronization when the motor is driven as a synchronous motor even if the amount of the laundry changes.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a main part of an inverter device according to a first embodiment of the present invention.

FIG. 2 is a drive control flowchart of a motor of the inverter device according to the first embodiment of the present invention;

FIG. 3 is a block diagram of a main part of the electric washing machine provided with the inverter device.

FIG. 4 is a drive control time chart of a motor of the inverter device.

FIG. 5 is a diagram showing operation waveforms of main parts of the inverter device.

FIG. 6 is a drive control time chart of the electric motor of the inverter device according to the second embodiment of the present invention.

FIG. 7 is a diagram showing operation waveforms of main parts of the inverter device.

FIG. 8 is a drive control time chart of the motor of the inverter device according to the third embodiment of the present invention.

FIG. 9 is a drive control time chart of the motor of the inverter device according to the fourth embodiment of the present invention.

FIG. 10 is a circuit diagram of a main part of an electric washing machine according to a fifth embodiment of the present invention.

FIG. 11 is a circuit diagram of a main part of a conventional inverter device.

FIG. 12 is a drive control time chart of a motor of a conventional inverter device.

[Explanation of symbols]

 Reference Signs List 3 inverter circuit 3a-3f switching means 4 electric motor 4a-4c armature winding 4d permanent magnet 5 voltage detecting means 6 reference voltage setting means 7 comparing means 8 control means 9 applied voltage control means

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yasudo Kobayashi 1006 Kazuma Kadoma, Osaka Pref. Matsushita Electric Industrial Co., Ltd. F term (reference) 3B155 AA01 BB08 BB19 HB09 HC05 KA02 KB08 KB11 LC02 LC13 LC15 MA01 MA06 MA07 MA09 5H560 BB04 BB07 BB12 DA13 DA19 DC12 EB01 GG04 SS07 TT07 TT08 TT11 UA02 XA11

Claims (6)

[Claims] 1. An electric motor having a permanent magnet in a rotor and an armature winding in a stator, an inverter circuit connected to the electric motor, and control means for controlling on / off of switching means constituting the inverter circuit. An applied voltage control unit that controls an applied voltage of the armature winding, a voltage detection unit that detects a terminal voltage of the armature winding, and a comparison unit that compares an output voltage of the voltage detection unit with a reference voltage. Reference voltage setting means for setting the reference voltage, wherein the control means controls the motor as a synchronous motor and increases the speed of the motor, and when the speed of the motor reaches a predetermined value, the applied voltage The control means controls the voltage applied to the armature winding to a predetermined value for a certain period, and the control means controls the switching means according to the output of the comparison means. apparatus. 2. The control device according to claim 1, wherein when the speed of the motor reaches a predetermined value, the control device changes the instantaneous value of the output frequency of the switching device and controls the switching device in accordance with the output of the comparing device. Inverter device. 3. The inverter device according to claim 1, wherein the control unit turns off all the switching units when the speed of the motor reaches a predetermined value, and thereafter controls the switching units on and off according to the output of the comparison unit. 4. An applied voltage control means includes a first set value of an applied voltage of the armature winding, a second set value smaller than the first set value, and a second set value smaller than the second set value. Having a certain third set value and rotating the motor as a synchronous motor,
The applied voltage control means increases the applied voltage of the armature winding to the first set value in proportion to time, and when the speed of the motor reaches a predetermined value, the applied voltage control means When the applied voltage of the slave winding is controlled to the third set value, and the control means controls the switching means according to the output of the comparing means, the applied voltage control means increases the applied voltage from the second set value. The inverter device according to any one of claims 1 to 3. 5. An electric washing machine comprising the inverter device according to claim 1. 6. An applied voltage control means for detecting an amount of laundry to be applied, wherein the applied voltage control means applies a voltage applied to an armature winding according to an output of the applied amount detection means when the motor is started. The electric washing machine according to claim 5, which controls the following.