JP2010200439A - Motor drive unit for washing machine, and washing machine using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor drive unit that improves reliability in switching connection of a stator coil. <P>SOLUTION: When switching a contact of a relay 4 which switches the connection of the stator coil, application of a voltage to an inverter circuit 1 is stopped, and the contact is switched at a rotation speed at which an induction voltage of a motor becomes lower than a DC power supply voltage of the inverter circuit 1. The switching operation can be performed without supplying a current to a relay connecting point without using a current detection means, and the high reliability can be ensured at low cost. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a motor driving device for a washing machine that drives a DC brushless motor directly connected to a rotating drum that is rotatably arranged in a water tank so that the rotation axis direction is substantially vertical, horizontal, or inclined, and uses the same. It relates to the washing machine that was.

  Conventionally, this type of motor requires a low speed and a large torque when washing, and a high speed and low torque when dehydrating. If the characteristics of the DC brushless motor satisfying both of these conditions are satisfied, the size becomes large. Therefore, the NdFeB magnet is used so that the motor can be rotated at a high speed by the flux weakening control. For this reason, the current required by the motor at high speed increases, and the power consumption increases, resulting in a reduction in motor efficiency.

  As another method for avoiding this, a driving system for a washing machine motor that switches the connection mode of the stator coils has already been proposed (see, for example, Patent Document 1).

  As shown in FIG. 4, the winding of the stator 25 of the motor 26 including the rotor 24 and the stator 25 is a three-phase star connection, and the windings of each phase are, for example, a coil 27 and a coil 28. Two coils are connected in series. One terminal of the two coils connected in series is connected to the neutral point 29 of the star connection. The other terminal 30 is connected to a relay terminal. A lead wire is drawn from the point where these two coils are connected, and is connected to the terminal 31 of the relay. This relay is connected to a motor wire 33 of each phase from an inverter circuit 32 that drives another motor, and the motor wire 33 from the inverter circuit 32 is connected to a terminal 30 of a coil of each phase or a coil of each phase. A relay is arranged so as to select and connect one of the terminals 31 connected to the lead wire 31 drawn from the middle.

  As described above, the relay circuit 34 having a relay for switching the motor wire 33 from the inverter circuit 32 to which of the terminals from the motor is connected to the control circuit 35 that controls the system that drives the motor. Operates with the command from. The control unit 35 also issues a control command for the inverter circuit 32.

In such a configuration, the coils of each phase are relay-connected so that current flows through the two coils at low speed, and the number of turns of the stator coil is large. At high speed, the coils of each phase are relay-connected to lead wires from between the two coils so that current flows through one coil, and the number of turns of the stator coil is reduced. When switching the relay, first, voltage application from the inverter circuit 32 to the motor is stopped, and it is detected whether or not current is flowing through the motor wire 33, or an abnormal voltage due to a transient phenomenon is not generated. The switching is performed after a sufficient delay time is provided.
JP 2008-22665 A

  However, in the conventional configuration, when the connection is switched while the rotor is rotating, if the induced voltage of the motor is equal to or higher than the voltage of the DC power supply unit of the inverter circuit even when the voltage application is stopped, the regenerative energy Flows from the motor into the inverter circuit. Although the connection switching is practically a contact point such as a mechanical relay, since regenerative energy flows into the DC power supply unit, there is a problem that a spark or the like is generated at the contact point at the time of switching and the contact point is likely to deteriorate.

  In addition, it is possible to reduce the cost by miniaturizing the motor by switching the connection, but there is a problem that the cost reduction rate is low due to the cost of the current detection device, switching circuit, wiring, etc., and further cost reduction is desired. It was.

  The present invention solves the above-described conventional problems, and provides a motor driving device for a washing machine that improves the reliability of the switching contact when switching the connection form, and further reduces the cost, and a washing machine using the same The purpose is to do.

  In order to solve the conventional problem, the motor driving device for a washing machine according to the present invention has an induced voltage lower than the DC power supply voltage of the inverter circuit when the motor is rotated, and the first connection form and the second connection. By switching the relay after providing sufficient delay time that both the motor characteristics of the configuration satisfy the load characteristics at the time of relay switching and abnormal voltage due to transient phenomenon does not occur, the current of the current detection device Even without confirmation, the relay contacts can be prevented from being deteriorated and switched, and the cost can be reduced.

  Also, a washing machine using this washing machine motor drive device can be made cheaper and more reliable.

  The motor driving device for a washing machine and the washing machine using the same according to the present invention can be made cheaper and more reliable.

  A first aspect of the present invention is a rotary drum that stores clothes and has a vertical, horizontal, or inclined rotation center shaft, a water tank that rotatably stores the rotary drum, and a brushless DC motor that is directly connected to the rotary drum. In this system, the stator coil is configured so that the connection form of the stator coil and an inverter circuit for driving the motor can be changed, and when the stator coil is rotated in the low speed region, the stator coil supports low speed rotation. When the motor is rotated in the high speed region, the second connection form corresponding to the high speed rotation is provided, and when the switching is performed by the connection control means, the load is connected to the first connection form. By satisfying both the motor characteristics of the configuration and the motor characteristics of the second connection configuration, The motor of ability can be enough to impart a, such as mechanical vibration and noise at the time of switching is less likely to occur. Further, when the connection is switched, since the induced voltage of the motor is less than the DC power supply voltage of the inverter circuit, no current flows during the operation of the switching relay, so that contact deterioration is less likely to occur and reliability is improved. It can be planned.

  In the second invention, in particular, in the first invention, by the connection form means, the first connection form is a star connection and the second connection form is a delta connection. The entire coil can be used effectively and wiring is easy.

  According to a third aspect of the present invention, in the first aspect of the present invention, in the first aspect of the present invention, the connection form is that a one-phase coil is composed of two coils connected in series, and a lead wire is provided between the two coils. Each of the first connection form and the second connection form is formed by switching the terminal of the end and the terminal of the lead line by the connection form means, thereby forming the first connection form and the second connection form. Since combinations of motor characteristics can be freely provided, an optimum form can be obtained in accordance with use conditions.

In the fourth aspect of the invention, in particular, in any one of the first to third aspects, the magnet of the motor is a ferrite magnet, so that the cost can be reduced.

  In the fifth aspect of the invention, in particular, in any one of the first to fourth aspects of the invention, the stator coil is made of aluminum as a conductor, so that the cost can be reduced.

  In a sixth aspect of the invention, in particular, in any one of the first to fifth aspects of the invention, the connection form control means performs control to switch between the first connection form and the second connection form after the motor stops. As a result, the reliability of the relay contact can be improved.

  In a seventh aspect of the invention, in particular, in any one of the first to sixth aspects of the invention, when the connection form control means switches between the first connection form and the second connection form, the motor characteristics satisfy a load condition. Thus, by performing the lead angle control or the magnetic flux weakening control, it is not necessary to increase the size of the motor only by responding to the load at the time of switching, so that the motor can be reduced in size and thereby reduced. Cost can be reduced.

  In the eighth aspect of the invention, in particular, the washing machine having the motor driving device for a washing machine according to any one of the first to seventh aspects of the invention can achieve a lower cost and higher reliability.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 shows the configuration of the motor drive apparatus according to Embodiment 1 of the present invention.

  As shown in FIG. 1, in the motor drive device in the present embodiment, an inverter circuit 1 that performs motor drive is controlled by a command from a control unit 2. A motor wire 3 connected from the inverter circuit 1 to the stator coil of the motor is connected to a terminal of the relay 4. One of the other selected terminals 5 and 6 of the relay 4 is connected to the end of a one-phase stator coil. The one-phase stator coil is composed of two coils connected in series, and is connected to a terminal 6 by providing a lead wire 7 from a location between the two coils. The other end of the one-phase stator coil is connected to a neutral point 8 and is a star connection in which three-phase stator coils are connected at the neutral point.

  In the motor driving device configured as described above, during a washing operation that requires a large torque at a low speed, a state in which the number of turns of the stator coil is large as in the case of the washing operation state (a) in FIG. It has become. On the other hand, at the time of high speed rotation and low torque dewatering operation, the number of turns of the stator coil is small as in the case of connection (b) in the dewatering operation of FIG. These two connection states are switched by the relay 4.

On the other hand, FIG. 2 is a graph showing the relationship between rotational speed and torque. The motor characteristic during the washing operation, that is, the motor characteristic 11 during the first connection configuration satisfies the load point 12 during the washing operation and the load point during the relay switching, and the motor characteristic during the dehydration operation, that is, the motor during the second connection configuration. The characteristic 13 satisfies the load point 14 at the time of dehydration operation and the load point at the time of relay switching. When the conditions of the DC power supply applied to the motor are the same, the motor characteristics of the low speed / large torque and the motor characteristics of the high speed / low torque can be changed by changing the number of turns of the stator coil of the motor. Is possible. The induced voltage of the motor when switching the relay is set to a value lower than the DC power supply voltage of the inverter circuit 1. Since the induced voltage of the motor is almost proportional to the rotational speed, the upper limit of the rotational speed when switching between the inverter circuit 1 and the motor constant is determined. When this switching is performed while the motor is rotating, first, the voltage application of the inverter circuit 1 is stopped at a rotation speed lower than a predetermined switching upper limit, and a delay time is set so as not to cause a transient abnormal voltage. Next, a relay switching operation is performed, and after applying a delay time until the connection state becomes completely stable, the relay is applied to drive the motor again.

  When the relay 4 is switched, the voltage applied to the motor of the inverter circuit 1 is stopped, and the induced voltage of the motor is smaller than the DC power supply voltage of the inverter circuit 1, so that regenerative energy does not flow into the inverter circuit 1, and a transient phenomenon occurs. Since current due to the abnormal voltage does not flow, even if the contact is switched, a phenomenon such as a spark that significantly deteriorates the contact does not occur, so that high reliability can be achieved. Moreover, since efficiency reduction due to the magnetic flux weakening control can be prevented, particularly high efficiency can be achieved at high speed rotation. Furthermore, since the efficiency is improved, the motor size can be reduced, so that the amount of material used can be reduced and the cost can be reduced.

  In the present embodiment, since the number of turns in the first connection form and the number of turns in the second connection form can be set freely, it is possible to set an optimum stator coil constant according to the use conditions of the motor. It is.

  When the load point 12 during the washing operation and the load point 14 during the dehydration operation are satisfied only by the characteristics of the motor alone, and the load point 15 during the relay switching is not satisfied, when the relay is switched by the advance angle control or the weak magnetic flux control. The load point 15 may be driven.

  Further, since the present invention does not need to actively use the flux-weakening control, demagnetization is likely to occur due to a reverse magnetic field, and the cost can be reduced by using a ferrite magnet that is cheaper than the NdFeB magnet.

  Furthermore, the cost of the stator coil can be further reduced by using aluminum which is cheaper than copper.

  If the washing / rinsing water is drained before the high-speed dehydration operation, the load at the time of start-up is reduced, and the load point at the time of start-up is satisfied by the motor characteristics 13 in the second connection form, Needless to say, the relay may be switched while the motor is stopped.

(Embodiment 2)
Next, a second embodiment of the present invention will be described based on FIG.

  In the motor drive device according to the present embodiment, the inverter circuit 16 that drives the motor is controlled by a command from the control unit 17. A motor wire 18 connected from the inverter circuit 16 to the stator coil of the motor is connected to the end 20 of the stator coil 19. The other end 21 of the stator coil 19 is connected to a relay 22 and connected to a neutral point 23 via the relay 22, and the end 21 of the stator coil is connected to either the neutral point 23 or another motor wire 18. It is provided to connect. When all the relays are operated so that the end 21 of the stator coil becomes the other motor wire 18, a delta connection is obtained as shown in the state (b) during the dehydrating operation.

  In the motor drive device configured as described above, during the washing operation that requires a large torque at a low speed, the connection in the state (a) during the washing operation of FIG. 3 is established. On the other hand, at the time of high-speed rotation and low-torque dehydration operation, the connection is as shown in FIG. These two connection states are switched by the relay 22. In this way, it is possible to change between low-speed and large-torque motor characteristics and high-speed and low-torque motor characteristics.

The induced voltage of the motor when switching the relay is set to a value lower than the DC power supply voltage of the inverter circuit 16. Since the induced voltage of the motor is substantially proportional to the rotational speed, the upper limit of the rotational speed when switching between the inverter circuit 16 and the motor constant is determined. When this switching is performed while the motor is rotating, first, voltage application to the inverter circuit 16 is stopped below a predetermined upper limit rotation speed to provide a delay time that does not cause an abnormal voltage of a transient phenomenon. Next, after switching operation of the relay and providing a delay time until the connection state becomes completely stable, a voltage is applied from the inverter circuit 16 in order to drive the motor again.

  When the relay 22 is switched, the voltage applied from the inverter circuit 16 to the motor is stopped, and the induced voltage of the motor is smaller than the DC power supply voltage of the inverter circuit 16, so that regenerative energy does not flow into the inverter circuit 16, and a transient phenomenon occurs. Since current due to the abnormal voltage does not flow, even if the contact is switched, a phenomenon such as a spark that significantly deteriorates the contact does not occur, so that high reliability can be achieved. In addition, since efficiency reduction due to the magnetic flux weakening control can be prevented, particularly high efficiency can be achieved at high speed rotation. Furthermore, since the efficiency is improved, the motor size can be reduced, so that the amount of material used can be reduced and the cost can be reduced.

  Even in the case of high-speed rotation in this embodiment, since all the coils are used, the copper loss can be reduced, and high efficiency can be achieved. Further, since no additional wiring such as a new lead line is required, the connection configuration is easy.

  As described above, the motor driving system for a washing machine according to the present invention can achieve high efficiency, small size, and high reliability at a wide range of load points. It can be widely applied to applications such as equipment and industrial equipment. Furthermore, the motor drive system can be applied to a compressor and a liquid pump from the same viewpoint.

(A) Connection diagram during washing operation of stator coil of motor drive device according to Embodiment 1 of the present invention (b) Connection diagram during dehydration operation Graph showing the relationship between rotational speed and torque (A) Connection diagram during washing operation of stator coil of motor drive device according to embodiment 2 of the present invention (b) Connection diagram during dehydration operation Configuration diagram of a conventional motor drive device

DESCRIPTION OF SYMBOLS 1 Inverter circuit 2 Control part 3 Motor wire 4 Relay 5 Terminal 6 Terminal 7 Lead wire 8 Neutral point 20 Terminal 21 Terminal 22 Relay 23 Neutral point 24 Rotor 25 Stator 26 Motor 27 Coil 28 Coil 29 Neutral point 30 Terminal 31 terminal 32 Motor wire 33 Inverter circuit 34 Relay circuit 35 Control unit

Claims (8)

In the system for rotating clothes, a rotating drum having a vertical or horizontal or inclined rotation center shaft for storing clothes, a water tank for rotatably storing the rotating drum, and a brushless DC motor directly connected to the rotating drum, the stator The coil is configured so that the connection form of the stator coil and the inverter circuit for driving the motor can be changed. When the stator coil is rotated in the low speed region, the first connection form corresponding to low speed rotation is adopted. When the motor is rotated in the high speed region in the previous period, it is provided with connection form control means having a second connection form corresponding to high speed rotation, and when switching by the connection control means, the motor characteristics when the load is in the first connection form are provided. And the motor characteristics in the second connection configuration are satisfied, and the induced voltage of the motor Washer motor driving system, wherein the circuit is less than the DC supply voltage. 2. The motor driving apparatus for a washing machine according to claim 1, wherein the first connection form is a star connection and the second connection form is a delta connection by the connection form means. In the connection form, a one-phase coil is formed of a series connection of two coils, and a lead wire is provided between the two coils, and the terminal of the end of the two coils and the terminal of the lead wire are connected. 2. The motor driving device for a washing machine according to claim 1, wherein the first connection form and the second connection form are formed by switching with form means. The motor driving apparatus for a washing machine according to any one of claims 1 to 3, wherein the magnet of the motor is a ferrite magnet. The motor driving apparatus for a washing machine according to any one of claims 1 to 4, wherein the stator coil has a conductor made of aluminum. The washing machine according to any one of claims 1 to 5, wherein the connection form control means performs control to switch between the first connection form and the second connection form after the motor stops. Motor drive device. The lead angle control or the flux weakening control is performed so that the motor characteristic satisfies a load condition when the connection form control means switches between the first connection form and the second connection form. The motor drive device for washing machines of any one of -5. A washing machine comprising the washing machine motor drive device according to any one of claims 1 to 7.

Images