JPH08237985A - Electric motor drive - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a motor drive device that switches the motor characteristics of a single-phase induction motor according to the load state and always drives the motor with minimum input power. The electric motor characteristic is simulated in the control device 3 by using the detected speed detected by the electric motor speed detecting means, and a characteristic switching means 32 for adjusting the electric motor characteristic by switching a capacitor according to a load state is provided. The motor characteristics are switched so that the input power of is minimized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor drive device,
In particular, the present invention relates to a capacitor-driving-type motor drive device in which a load varies depending on an operating state and a large starting torque is obtained when starting a single-phase induction motor.

[0002]

2. Description of the Related Art A conventional electric motor drive device is disclosed in Japanese Patent Laid-Open No. 62-19 / 1987.
As described in Japanese Patent No. 199, when the motor load varies depending on the operating conditions, operate a capacitor with a relatively large capacity to obtain a large starting torque and a capacitor with a relatively small capacity to operate at a steady rotation speed. Switch to the inside and drive. The winding of the single-phase induction motor is designed according to the starting torque, and a large starting torque is obtained in combination with a capacitor having a large capacity. On the other hand, when operating at a steady rotation speed, a relatively small capacitor is used for optimization. The two capacitors having different capacities are switched according to the operation time depending on the relationship between the load state and the time, and the operation is reduced in noise.

[0003]

The above-mentioned prior art is to switch capacitors having different capacities during operation according to time to suppress current distortion and reduce noise. But,
It does not optimally reduce the input power during operation.

[0004]

In order to solve the above problems, the present invention relates to a motor drive device for switching and operating a plurality of capacitors for adjusting the torque of a single-phase induction motor based on a signal from a control device. The control device includes characteristic switching means for simulating the speed-torque characteristic of the electric motor, detecting the torque of the electric motor, switching a plurality of capacitors according to the torque, obtaining an appropriate torque, and minimizing the input power. I did it.

Further, the control device is provided with a characteristic switching means for calculating the motor output from the rotation speed and the torque, switching a plurality of capacitors according to the motor output, and minimizing the input power.

Also, the electric motor drive device is used in the rotary drive component of a washing machine that performs washing / dewatering operation with a single electric motor.

[0007]

The electric motor drive device of the present invention configured as described above simulates the electric motor characteristics to detect the torque, and switches a plurality of capacitors to obtain an appropriate torque characteristic, thereby responding to the load condition. It is possible to reduce the input power during operation.

Further, by detecting the electric motor output from the detected torque and rotational speed and switching a plurality of capacitors to obtain an appropriate electric motor output, it is possible to reduce the output fluctuation at the time of switching.

Further, by operating the washing machine by using the electric motor drive device capable of changing the electric motor characteristics in accordance with the load condition, a washing machine which always operates with minimum power consumption in a series of washing and dehydrating steps is realized. it can.

[0010]

Embodiments of the present invention will be described below with reference to FIGS. 1, 2 and 3.

FIG. 1 is a block diagram of an electric motor drive device according to an embodiment of the present invention. The motor drive device according to the present invention supplies power from the AC power supply 1 to the single-phase induction motor 2 via the triac T3 or T4. The electric motor speed N is detected by the speed detecting means TG, the electric motor output is obtained by the control device 3, and the combined capacity of the capacitors C1, C2 and C3 is adjusted to obtain an appropriate torque of the electric motor and to minimize the input power. To control.

The single-phase induction motor 2 has a two-phase winding, and one of the capacitors C1, C2 and C4 is connected to the AC power source 1 by conduction of one of the triac T3 or T4 inserted in series.
One of the three windings is inserted in series with one winding of the two-phase winding, and the rotation direction changes. The control device 3 outputs the gate signal G3 or G4 in response to the rotation direction command AL to bring the triac T3 or T4 into conduction to control the rotation direction of the single-phase induction motor 2. Further, the controller 3 controls the gate signal G1,
The triacs T1 and T2 are made conductive by G2, and the combined capacitance of the capacitors C1, C2 and C3 is adjusted. The capacitor C3 is a capacitor that is always inserted in the circuit,
Determine the minimum value of the capacitance of the capacitor inserted in the circuit.
The capacitor advances the phase of the winding current by inserting it in series with one of the two-phase windings of the single-phase induction motor 2, and increases or decreases the motor torque according to the capacity of the capacitor. If the capacity of the capacitor connected to the single-phase induction motor 2 is large, the starting torque and the stalling torque increase, but the input power also increases.

FIG. 2 is a block diagram of a control device according to an embodiment of the present invention. The characteristic simulation device 30 stores the electric motor characteristic corresponding to the capacitor capacity, and obtains the torques TO1, TO2, TO3 of the respective characteristics from the rotation speed N. The torque setter 34 estimates the load torque level TR from the load mode MOD. The comparison calculator 31 determines the load torque level T
R and the torques TO1, TO2, TO3 of the respective characteristics are compared, and the smallest characteristic among the operable characteristics is selected. The characteristic switching unit 32 creates a signal so as to have a capacitor capacity that realizes the characteristic selected by the comparison arithmetic unit 31, and outputs it as the gate signals G1 and G2 via the drive circuit. On the other hand, the rotation direction of the electric motor is given by the rotation direction command AL, the rotation direction signal generator 33 generates a signal for determining the rotation direction, and the gate signal G3 is generated via the drive circuit 35.
Output as G4.

FIG. 3 shows an explanatory diagram of the operation of the control device in one embodiment of the present invention. The figure shows the speed-torque characteristic of the electric motor depending on the capacitor capacity. The characteristics T1, T2, T3 are in the order of increasing capacitor capacity inserted in the circuit. The control device 3 obtains the load torque level TR from the load mode MOD, and selects the characteristic with which the comparison calculator 31 can obtain the required starting torque. The comparison calculator 31 constantly compares each characteristic (torque) according to the rotation speed N, determines that the characteristic is the smallest, and determines the capacitor capacity to be inserted in the circuit. That is, when the load torque level TR is large and the starting torque is required, the engine starts with the characteristic T1, the rotation speed N increases, and the vehicle can be operated with the characteristic T2 (the torque of the characteristic T2 is larger than the load torque level TR), the characteristic T2. Switch to. When the rotation speed N further increases and the operation can be performed with the characteristic 3, the characteristic is switched to the characteristic 3 and the torque pattern DR of the electric motor becomes a thick line. Here, it suffices that the load torque level TR agrees with the actual load torque. However, if there is a load fluctuation or an error in the load torque level TR, the rotation speed N will decrease after switching to a smaller characteristic, and the load torque will decrease. The value of level TR is corrected to a large value, and a large characteristic is switched. As a result, the input power can be minimized by selecting the characteristic according to the load state. In this embodiment, the triac is used for switching the circuit, but it may be configured by a mechanical switch such as a relay or a semiconductor switching element so that alternating current can be supplied.

Next, another embodiment of the present invention will be described with reference to FIGS.

FIG. 4 is a block diagram of a control device according to another embodiment of the present invention. The control device in the present invention is shown in FIG.
Is different from the characteristic simulation device 30 at the input of the comparison calculator 36.
This is because the motor output O1, O2, O3 obtained by multiplying the output torques TO1, TO2, TO3 of No. 1 by the rotation speed N is used. When the maximum output characteristic is selected and the rotation speed N increases, the characteristic is switched to operate when the motor output becomes smaller than a predetermined set value.

FIG. 5 is an explanatory diagram of the operation of the control device in another embodiment of the present invention, showing the relationship between the input / output and the rotation speed. When the rotation speed N is 60% or less of the synchronous speed, the operation is performed with the characteristic of the capacitor capacity of 100 μF to obtain the maximum output, the rotation speed N becomes large, and the motor output becomes the output set value P.
When o1 is reached, the characteristic is switched to a capacitor capacity of 70 μF. At this time, the input power at the rotation speed N1 is 10
It can be reduced by about 0W. When the rotation speed N further approaches the synchronous speed (in the vicinity of the rotation speed N2), the output reaches the set value Po2, and the input power can be further reduced by about 70 W by switching to a smaller capacitor capacity of 30 μF. Motor output P
If out has substantially the same value, the smaller the input power Pin, the better, and the operation is switched to the capacitor capacity that requires only a small input power. By switching the capacitor capacity using the electric motor output calculated in this way, vibration and noise at the time of switching can be suppressed, the change in rotation speed can also be minimized, and operation can be performed with the minimum input power that is in the operating state.

Next, a system to which the motor drive device of the present invention is applied will be described with reference to FIG.

FIG. 6 is an explanatory view of a washing machine according to another embodiment of the present invention. In this embodiment, the operation command device 11 operates the washing machine according to the output signal of the weight sensor 12 that detects the amount of laundry. That is, the washing mode is determined according to the amount of laundry, and the load mode MOD is used as the electric motor drive device 10.
The starting torque is adjusted to drive the single-phase induction motor 2.
Further, the operation command device 11 controls the rotation direction of the electric motor according to the operation status. The driving force generated by the electric motor is transmitted to the gear / clutch 17 via the pulley / belt 18 to rotate the pulsator 16 during washing and rotate the basket 15 during dehydration. These are attached to an outer tub 14 for storing water, which is hung on a washing machine body 20 with a hanging rod 13. Since the load state differs between washing and dehydration, the operation command device 11
Output changes and the capacitor capacity in the motor drive device 10 is set appropriately. That is, the starting torque during washing is relatively small, but the load rapidly increases as the rotation speed increases, so it is necessary to select a relatively large capacitor capacity.

On the other hand, the starting torque at the time of dehydration requires a large starting torque because the laundry absorbs water and is heavy, and the largest capacitor capacity is selected in order to quickly pass the unbalance vibration point at the initial stage of starting. When the operating time elapses to some extent, the rotation speed increases and the laundry is drained of water to reduce the load. Therefore, the condenser capacity is switched to an appropriate value. According to the present embodiment, the capacity of the condenser is switched to obtain the optimum torque for washing and dehydration, and the operation is performed, so that the input power can be reduced. In particular, since a series of operating time of the washing machine is as long as 30 minutes or more, power consumption in the entire washing process can be suppressed.

[0021]

According to the present invention, the input electric power at the time of operation is reduced by matching the electric motor characteristics with the load condition so as to have a large characteristic when a starting torque is required and switching it to a smaller characteristic according to the operating condition. effective.

Further, according to the present invention, the operation of the washing machine is performed by using the electric motor drive device which changes the electric motor characteristic to a large characteristic when the starting torque is required in accordance with the load state and switches to a smaller characteristic according to the operating state. By doing so, there is an effect that operation with a minimum power consumption is always realized in a series of washing and dehydration processes.

[Brief description of drawings]

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

FIG. 2 is a block diagram of a control device according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram of the operation of the control device in the embodiment of the present invention.

FIG. 4 is a block diagram of a control device according to another embodiment of the present invention.

FIG. 5 is an explanatory diagram of the operation of the control device according to another embodiment of the present invention.

FIG. 6 is an explanatory view of a washing machine according to another embodiment of the present invention.

[Explanation of symbols]

3 ... Control device, 30 ... Characteristic simulation device, 32 ... Characteristic switching device, 36 ... Comparison arithmetic unit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kunio Miyashita Kunio Miyashita 1-1-1, Higashitaga-cho, Hitachi-shi, Ibaraki Hitachi Ltd. Electric Appliances Division, Taga Headquarters (72) Inventor Hisamitsu Gomida Higashi-shi, Ibaraki 1-1-1 Taga-cho, Electric Appliances Division, Hitachi Ltd., Electric Works Division, Taga Headquarters (72) Inventor Takeo Konno 1-1-1, Higashi-Tagacho, Hitachi City, Ibaraki Prefecture Taga Headquarters, Electrical Equipment Division, Hitachi, Ltd. (72) Inventor Kazuyoshi Moriyama 1-1-1, Higashitaga-cho, Hitachi-shi, Ibaraki Nitate Taga Engineering Co., Ltd.

Claims (3)

[Claims] 1. A motor drive device comprising a single-phase induction motor, a plurality of capacitors for adjusting the torque of the single-phase induction motor, and a controller for switching and operating the capacitors, wherein the controller is the single-phase induction motor. A characteristic switching means for simulating an electric motor characteristic from the rotation speed of the motor to detect a torque, switching the plurality of capacitors according to the torque of the single-phase induction motor, obtaining an appropriate torque, and minimizing the input power. An electric motor drive device characterized by the above. 2. The control device according to claim 1, wherein an output of the single-phase induction motor is calculated from a rotation speed and a torque,
An electric motor drive device comprising a characteristic switching unit that switches the plurality of capacitors according to the output of the single-phase induction motor and minimizes input power. 3. A washing machine in which any one of the motor drive device according to claim 1 and claim 2 is used as a rotary drive component for washing / spinning operation with a single single-phase induction motor.