JP2009082534A - Drum-type washing machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a rotation speed sensor to be eliminated, to reduce costs and to increase reliability while maintaining the rotation speed controlling performance in a drum-type washing machine. <P>SOLUTION: A separate excitation direct current motor 4 is used for the motor, and at the same time, this drum-type washing machine is equipped with an armature resistance calculating section 71, a rotation speed calculating section 72, and an applying voltage setting section 73 as a controlling mechanism 7 for controlling the separate excitation direct current motor 4. In this case, the armature resistance calculating section 71 calculates an armature resistance from an armature current being measured for a specified period and an inter-terminal voltage being applied at that time in the middle of a deceleration until the motor 4 stops after a field current is zeroized in the step of repeating the start/stoppage of the motor 4 by turning on/off of the field current. The rotation speed calculating section 72 calculates the rotation speed of the motor 4 with the armature resistance, the armature current and inter-terminal voltage as parameters. The applying voltage setting section 73 calculates the inter-terminal voltage which should be applied at least based on a deviation between an estimated rotation speed being the rotation speed which has been calculated by the rotation speed calculating section 72, and a target rotation speed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a drum-type washing machine capable of suitably controlling speed without using a rotational speed sensor.

The separately excited DC motor is a DC motor having a field circuit and an armature circuit independently as is well known, and is a so-called servo by combining it with a high-performance rotation speed sensor and a feedback control mechanism. A drive motor can be configured. This servo drive motor is used in applications that require high responsiveness, high positioning accuracy, high speed controllability, etc., and in such applications, performance and characteristics are greatly degraded due to sensorlessness. Sensors are considered essential.
In applications where it is only necessary to rotate at an appropriate speed that balances the load without feedback control, such as when using a separately excited DC electric motor for a power tool, vacuum cleaner, mixer, etc., the rotational speed is not controlled in the first place. The sensor is not attached.

By the way, also in the drum type washing machine, conventionally, control of the drum rotation speed using a rotation speed sensor has been performed (see Patent Document 1). The drum-type washing machine has a low rotational speed in the washing process and a high rotational speed in the dewatering process, and the speed control range is so wide that the nonlinearity cannot be ignored. Since a certain degree of speed control accuracy is required, open loop control is difficult, and it is considered that feedback control using a rotational speed sensor is still necessary.
JP 2006-288706 A

  However, the rotation speed sensor causes a failure or malfunction, lowers the reliability of the product, and causes a high cost. Conventionally, in order to solve this problem, TG (Tacho Generator) and Hall IC with low resolution are used as the rotation speed sensor because of the specification characteristics of the washing machine that high responsiveness is unnecessary. No drastic solution has been reached.

  Therefore, the present invention has an intermittent operation unique to a washing machine, that is, an operation of frequently repeating start and stop of the motor, and a configuration unique to a separately excited DC motor that can independently control the field circuit and the armature circuit. It was made for the first time by paying attention to the above, and by combining them, each of which was considered to be essential for a rotational speed sensor alone, not only cost reduction and reliability improvement due to sensorlessness became possible, but also accuracy The main objective of the present invention is to provide a drum type washing machine capable of high speed control.

That is, the drum type washing machine according to the present invention adjusts the voltage applied to the armature of the motor, the drum to which the laundry is put, the separately excited DC motor that rotationally drives the drum, and the rotation of the motor. And a control mechanism that performs control to bring the speed close to a predetermined target rotational speed.
The control mechanism repeats starting and stopping of the motor by turning on / off the field current. For example, in the washing process, during the deceleration until the motor stops after the field current is set to 0, the control mechanism is measured for a certain period. An armature resistance calculation unit for calculating an armature resistance from the armature current and the voltage between terminals applied at that time, and the rotation speed of the motor using the armature resistance, the armature current and the voltage between terminals as parameters A rotation speed calculation unit that calculates the voltage, and an application voltage setting unit that calculates a voltage between terminals to be applied based at least on the estimated rotation speed calculated by the rotation speed calculation unit and a deviation of the target rotation speed; It is characterized by comprising.

  When using a separately excited DC motor to achieve sensorlessness, it is necessary to measure the armature resistance as one method for estimating and calculating the rotational speed. However, the armature resistance varies finely depending on the contact area between the commutator and the brush, contact pressure, etc., and an accurate value cannot be measured in a stationary state, so the rotational speed calculated from the inaccurate resistance value. Will also be inaccurate.

On the other hand, with the configuration described above, the armature resistance is measured not over a stationary state but over a certain period during rotation of the electric motor. The difference is canceled (averaged), closer to the true value, and becomes a highly accurate value. Since the rotation speed is calculated using the armature resistance value calculated with high accuracy and feedback control is performed based on the calculated value, more accurate rotation speed control can be performed.
In addition, since the field current is measured in a state of 0, it is not necessary to consider the influence of the field current on the armature, and a simple calculation that divides the terminal voltage of the armature by the armature current. The child resistance can be calculated.

  In order to calculate the armature resistance almost in real time and to compensate for the dynamic change of the resistance value caused by the temperature rise of the winding due to the operation of the motor, the armature resistance calculation unit It is desirable to calculate the armature resistance at each stop.

  In order to enable disturbance response compensation caused by the fall of the laundry in the washing process using the disturbance estimation effect of the armature current, the rotation speed calculation unit is configured to use the measured armature current and the electric machine Based on the child resistance, the difference voltage obtained by subtracting the back electromotive force from the terminal voltage is estimated and calculated, and the rotation speed of the motor is calculated based on the value obtained by subtracting the difference voltage from the applied terminal voltage. It is preferable.

  On the other hand, in order to perform suitable speed control without a rotation speed sensor, for example, in the dehydration process, the control mechanism is connected between the weight calculation unit that calculates the weight of the laundry and the terminal that is applied between the terminals of the armature. Based on at least a deviation between the target rotational speed and a rotational speed calculation unit that calculates the rotational speed of the electric motor using the voltage and the laundry weight as parameters, and the estimated rotational speed that is the rotational speed calculated by the rotational speed calculation unit And an applied voltage setting unit for calculating a voltage between terminals to be applied. In the dehydration process, speed control over a wide range is required.In such a case, if the rotational speed is estimated and calculated only from the voltage, current, and resistance between the terminals of the armature, errors due to nonlinear effects will occur. It is because it becomes remarkable.

A specific rotational speed calculation formula found by the present inventors as a result of intensive studies is as follows.
Here, ω _r is an estimated rotational speed, Va is _a voltage between terminals, and α, V _o , and q are coefficients determined by linear functions of the laundry weight.

  As described above, according to the present invention, an advanced signal processing technique is not required, and the amount of laundry that can be performed by a conventional washing machine and the resistance value measurement at each stop can be measured without using a rotation speed sensor. Thus, it is possible to calculate the rotational speed with high accuracy and realize high speed controllability. And it becomes possible to achieve cost reduction and reliability improvement by sensorless.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a longitudinal sectional view showing a schematic internal structure of a drum type washing machine 100 according to the present embodiment. In the figure, reference numeral 1 denotes a hollow body. On the use end side (hereinafter also referred to as the front side) of the body 1, there are an input port 11 for inputting laundry, and an input port 11 for closing the input port 11. A lid 12 that can be opened and closed is provided. Further, a water tank 2 is disposed inside the body 1, and a drum 3 is provided further inside the water tank 2.

  The water tank 2 has a substantially cylindrical shape in which a rear end face is closed by a bottom plate 21 and an opening 22 is provided in a front end face, and the center axis C is inclined from horizontal or horizontal, and the front side is more than the rear side. It is supported by the damper D and the elastic body S so as to be able to swing in a slightly higher posture. The opening 22 is connected to the insertion port 11 of the body 1 via a flexible cylindrical body 23.

  The drum 3 has a cylindrical shape that is slightly smaller than the water tank 2. Like the water tank 2, the rear end surface is closed by the bottom plate 31, and an opening 32 is provided on the front end surface. The drum 3 is provided with a large number of holes 33 penetrating in the thickness direction, so that water can enter the drum 3 from the water tank 2 through the holes 33. Also, lifters 34 having a ridge shape for hooking and lifting the laundry are provided at a plurality of locations (three locations) on the inner peripheral surface of the drum.

On the outside of the bottom plate 21 in the water tank 2, for example, an electric motor 4 for rotationally driving the drum 3 is attached. A rotating shaft 41 of the electric motor 4 passes through the bottom plate 21 through a bearing 42, and the drum 3 The bottom plate 32 is fixed.
This motor 4 is called a separately excited DC motor, and as shown in FIG. 2, has a field circuit 4f and an armature circuit 4a, and a voltage V _f applied to each of the circuits 4f and 4a, V _a can be controlled independently.

  Reference numeral 5 denotes a water supply mechanism 5 for supplying washing water. The water supply mechanism 5 includes a water supply pipe 51 connected to an external water pipe and an electromagnetic opening / closing valve 52 provided in the middle of the water supply pipe 51. The tip injection port 51a of the water supply pipe 51 is disposed so as to face the opening 32 of the drum 3, and is configured so that water can be directly poured onto the laundry inside the drum 3 from the injection port 51a. ing.

  Reference numeral 6 denotes a drainage mechanism for discharging the washing water in the water tank 2 and the drum 3 to the outside. The drainage mechanism 6 includes a drain pipe 61 connected to the lowermost part of the water tank 2, that is, a rear end lower part of the water tank 2, and an electromagnetic opening / closing valve 62 provided in the middle of the drain pipe 61.

In addition to these configurations, the washing machine 100 controls the electromagnetic open / close valves 52 and 62, the electric motor 4, and the like to automatically perform a washing process and a dehydrating process (not shown in FIG. 1). Is not provided in the body 1.
As shown in FIG. 3, the control mechanism 7 includes a CPU, a memory, various driver circuits, etc., as shown in FIG. 3, and the CPU and peripheral devices cooperate in accordance with a program stored in the memory. Various functions are demonstrated by moving.

In the washing step, as shown in the functional block diagram of FIG. 4, the control mechanism 7 exhibits at least functions as an armature resistance calculation unit 71, a rotation speed calculation unit 72, and an applied voltage setting unit 73. Thus, the program is configured so that the control block shown in FIG. 5 is formed.
Therefore, first, the operation of the drum-type washing machine 100 in the washing process will be described together with the function explanation of the control mechanism 7.

<< Washing process >>
First, when the operator puts the laundry into the drum 3, closes the lid 12, and presses a start button on a control panel (not shown), the washing process is started. At this time, as shown in FIG. 6, intermittent operation by ON / OFF control of the field current, that is, start / stop is repeated.

  Then, after the field current is turned off, the armature resistance calculation unit 71 in the control mechanism 7 measures the armature current and decelerates until the motor 4 stops rotating. The armature resistance is calculated from the applied inter-terminal voltage.

  More specifically, the armature resistance calculation unit 71 reduces the armature current when, for example, the motor 4 is still rotating in the OFF period of the field current (or field voltage). The armature resistance is calculated by measuring using the current measuring circuit 75 composed of resistance and the like, and dividing the voltage between the terminals applied at that time by the measured current value (see Expression (5)).

The theoretical reason is as follows.
That is, the relationship between the armature terminal voltage V _a and the armature current I _a is expressed by the following equation (Equation 3).
Here, R _a is the armature resistance, L _a is an inductance, the V _e is a counter electromotive force of the armature.
Further, the counter electromotive force V _e is represented by in proportion to the actual rotational speed of the electric motor 4 omega and the field current I _f the following equation (4).
Here, k is a counter electromotive force coefficient.

Now, the field current I _f is 0, the normal value of the L _a is negligibly small, the number 4 is given by the following equation (5).
Therefore, as described above, the armature resistance can be calculated by simply dividing the inter-terminal voltage by the measured current value.

In this embodiment, the armature resistance calculation unit 71 linearly changes the voltage between the terminals as shown in FIG. 7, and calculates the average of the values of the armature resistance calculated at a plurality of points in time during the subsequent calculation. The value of the armature resistance used in
In addition, the armature resistance calculation unit 71 calculates armature resistance in the same manner every time the motor 4 is stopped, and sets the armature resistance data as armature resistance data in a predetermined area of the memory in time series. In addition to storing, the latest data is used in the calculation related to the calculation of the rotational speed thereafter.

  Thus, the armature resistance obtained in this way is measured over a certain period during rotation of the electric motor 4 and is not obtained in a stationary state. Therefore, the contact between the brush and the commutator Differences in the state related to the area and contact pressure are canceled (averaged), and become a numerical value closer to the actual value. In addition, it can be said that the armature resistance is calculated in real time every time the motor 4 is stopped, so that it is possible to compensate for a dynamic change in the resistance value caused by the temperature rise of the winding due to the operation of the motor 4. Furthermore, in this embodiment, since the armature resistance is calculated in a linearly changed state, measurement errors caused by the resolution of the device such as an A / D converter can be reduced.

Next, rotation speed control will be described.
The output torque T of the electric motor 4 is expressed by the following equation (Equation 6) in proportion to the field current I _f and the armature current I _a .

Considering the ON state where the field current _If is constant, k · _If can be regarded as a constant K, so the equation (Equation 7) holds.

  In the electric motor 4, as shown in FIG. 5, the rotational speed is determined by the balance between the output torque T and the load and disturbance torque, the counter electromotive force is determined by the rotational speed, and the counter electromotive force is applied. A closed loop is formed in which the armature current is determined from the voltage between the terminals.

Thus, in this embodiment, the rotational speed calculating section 72 constituting a part of the control mechanism 7, from the measured armature current I _a and armature resistance R _a, determined by the rotational speed of the electric motor 4 at that time A differential voltage V _d obtained by subtracting the back electromotive force V _e is calculated. The calculation formula is the following formula (formula 8) obtained by modifying the formula (formula 3).

Then, subtracting the differential voltage V _d, the terminal voltage V _a that is currently applied.
Then, as is clear from this equation (Equation 9), the back electromotive force V _e is calculated.

Since the relationship between the counter electromotive force V _e and the actual rotational speed ω is proportional to the equation (Equation 4), the rotational speed calculating unit 72 uses the calculated counter electromotive force V _e as a proportional constant. By dividing by K (= k · I _f ), the rotational speed (estimated rotational speed) ω _r is estimated and calculated (see the following formula (Equation 10)).

Then, the applied voltage setting unit 73, based on a deviation between the estimated rotation speed omega _r and the target rotation speed omega _p, to set the voltage V _a across to be applied terminal.
The terminal voltage setting formula is, for example, the following formula (Formula 11).
Here _the K _D is a feedback coefficient.
The target rotation speed is stored in advance in a target rotation speed storage unit that is set in advance in a predetermined area of the memory, and the applied voltage setting unit 73 acquires a data value related to the target rotation speed from the target rotation speed storage unit. To do.

  In this way, in the present embodiment, a feedback loop as shown in the control block of FIG. 5 is configured to perform speed control.

As is apparent from FIG. 5, the armature current I _a is affected by the counter electromotive force V _e (see Equation 3), and the counter electromotive force V _e is determined by the actual rotational speed ω (several 4 and Equation 10), the actual rotational speed ω is affected by a load torque applied to the electric motor 4 and a disturbance torque caused by a fall of the laundry (see Expression (Equation 12)).
Here, _Td is disturbance torque, B is a resistance coefficient due to mechanical friction and viscosity, and J is inertia.

Therefore, it can be said that the armature current is affected by the load torque and the disturbance torque. According to this embodiment, the rotational speed at the time of the washing process is calculated based on the armature current and fed back. if, acts disturbance estimation effect by the armature current, by appropriately setting the K _D, it is possible to effectively suppress the disturbance.
In addition, such a configuration eliminates the need for a rotation speed sensor, thereby reducing costs and reducing parts.

  In addition, the concrete effect by experiment is shown in FIG. Here, the variation in rotational speed was measured when 30 sheets (total weight 3 kg) were washed with 14 liters of water. As apparent from the fact that the dot variation is small compared to FIG. 9 showing the controllability when the conventional rotational speed sensor is provided, the configuration according to the present embodiment can improve the speed control performance. Recognize. Therefore, it is possible to push forward the performance improvement and the price reduction as compared with the conventional case.

<< Dehydration process >>
Next, operation | movement in the spin-drying | dehydration process of the washing machine is demonstrated. In the dehydration process, as shown in the functional block diagram of FIG. 10, the control mechanism 7 is programmed so that it at least functions as the rotation speed calculation unit 72, the applied voltage setting unit 73, and the weight calculation unit 74. Is configured.

  Here, first, at an initial time until water supply in the washing process is started, the weight calculation unit 74 in the control mechanism 7 performs, for example, a laundry based on a time-dependent change in the armature current at the ON / OFF switching. And the data indicating the calculated value is stored in the weight storage unit D3 set in a predetermined area of the memory.

  In the dehydration process, the rotation speed calculation unit 72 calculates the rotation speed of the electric motor 4 using the voltage between the terminals applied between the terminals of the armature and the weight of the laundry calculated at the initial time as parameters.

Specifically, the rotation speed calculation unit 72 calculates the rotation speed based on the following calculation formula (Equation 13).
Here, α, V _o , and q are coefficients each represented by a linear function of the laundry weight M (see Equations 14 to 16). In these Equations 14 to 16, a, b, c, d , E, and f are constants appropriately determined by experiments and simulations.

Then, similarly to the washing step, the applied voltage setting unit 73, based on a deviation between the rotational speed omega _r and the target rotation speed omega _p, to set the voltage V _a across to be applied terminal.

  Therefore, according to such a configuration, the accuracy of the rotation speed calculated by the rotation speed calculation unit 72 is greatly improved, and as shown in the experimental results in FIG. 11, it is less than 5% over several tens of rpm to several thousand rpm. It becomes possible to suppress the speed error. As a result, the speed can be controlled with high accuracy, and the washing performance can be improved.

On the other hand, in the rotational speed estimation equation (Equation 17) using the inter-terminal voltage and the armature current as parameters used in the conventional separately-excited DC motor, in the wide speed control range as described above, as shown in FIG. Errors of up to about 30% can occur.

The present invention is not limited to the above embodiment. For example, in the embodiment, the rotation speed calculation unit 72 calculates the rotation speed without considering the laundry weight in the washing process, and calculates the rotation speed without considering the armature current in the dehydration process. For example, in the washing step, the rotation speed may be calculated by further adding the laundry weight as a parameter, or in the dehydration step, the rotation speed may be calculated by further adding the armature current as a parameter.
Moreover, you may utilize the said rotation speed calculation part in another process.
In addition, it goes without saying that the present invention can be variously modified without departing from the spirit of the present invention.

The schematic longitudinal cross-sectional view which shows the internal structure of the washing machine which concerns on one Embodiment of this invention. The typical block diagram of the separately excited direct current motor in the embodiment. The hardware block diagram of the control mechanism in the embodiment. The functional block diagram of the control mechanism in the washing process in the embodiment. The control block diagram in the washing process in the embodiment. FIG. 3 is a field current waveform diagram when the electric motor is intermittently operated in the same embodiment, and a speed change diagram showing a change in the rotational speed of the electric motor accompanying therewith. FIG. 4 is a waveform diagram of an armature current and an armature voltage given during a deceleration period in the same embodiment. The experimental data which show the result of speed control in the same embodiment. Experimental data showing the results of conventional speed control. The functional block diagram of the control apparatus in the spin-drying | dehydration process in the embodiment. The experimental data which show the result of speed control in the same embodiment. Experimental data showing the results of conventional speed control.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Washing machine 4 ... Separately excited DC motor 7 ... Control mechanism 71 ... Armature resistance calculation part 72 ... Rotational speed calculation part 73 ... Applied voltage setting part 74 ... Weight Calculation unit

Claims (5)

A drum into which the laundry is thrown in, a separately excited DC motor that rotationally drives the drum, and a voltage that is applied to the armature of the motor are adjusted so that the rotational speed of the motor approaches a predetermined target rotational speed. A control mechanism,
The control mechanism is
In the process of repeatedly starting and stopping the motor by turning the field current ON / OFF, the armature current measured for a certain period and applied at that time during deceleration until the motor stops after the field current is set to 0 An armature resistance calculation unit that calculates an armature resistance from the terminal-to-terminal voltage,
A rotational speed calculation unit that calculates the rotational speed of the motor using the armature resistance, the armature current, and the voltage between the terminals as parameters;
An applied voltage setting unit that calculates an inter-terminal voltage to be applied based on at least a deviation between an estimated rotation speed that is a rotation speed calculated by the rotation speed calculation unit and the target rotation speed; Type washing machine.   The drum type washing machine according to claim 1, wherein the armature resistance calculation unit calculates an armature resistance each time the motor is stopped. Based on the measured armature current and armature resistance, the rotational speed calculation unit estimates and calculates a differential voltage obtained by subtracting the back electromotive force from the terminal voltage,
The drum type washing machine according to claim 1 or 2, wherein the rotational speed of the electric motor is calculated based on a value obtained by subtracting the differential voltage from an applied inter-terminal voltage. A drum into which the laundry is thrown in, a separately excited DC motor that rotationally drives the drum, and a voltage that is applied to the armature of the motor are adjusted so that the rotational speed of the motor approaches a predetermined target rotational speed. A control mechanism,
The control mechanism is
A weight calculator for calculating the weight of the laundry;
A rotation speed calculation unit that calculates the rotation speed of the electric motor using the voltage between the terminals applied between the terminals of the armature and the weight of the laundry as parameters, and
An applied voltage setting unit that calculates an inter-terminal voltage to be applied based on at least a deviation between an estimated rotation speed that is a rotation speed calculated by the rotation speed calculation unit and the target rotation speed; Type washing machine. The drum type washing machine according to claim 4, wherein the rotation speed calculation unit calculates a rotation speed of the electric motor using a rotation speed calculation formula (Equation 1) stored in advance in a memory.
Here, ω _r is an estimated rotational speed, Va is _a voltage between terminals, and α, V _o , and q are coefficients determined by linear functions of the laundry weight.