JP2004015946A - Motor drive circuit arrangement for laundry instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor drive circuit arrangement for a laundry instrument which can reduce the area required for a circuit board and suppress the increase of manhour in work in the case of performing vector control, based on a phase current detected by a shunt resistor. <P>SOLUTION: IGBTs 29a-29f constitute an inverter circuit for applying AC power to each phase of winding 11u-11w of the motor 11 of a washing machine, and shunt resistors 23u-23w which detect the phase current of the motor so as to vector-control the motor 11 by sensorless system. The IGBTs are stored in one package so as to constitute an IMP21. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a motor drive circuit device for driving a motor of a laundry machine that performs an operation related to washing.
[0002]
[Problems to be solved by the invention]
For example, an inverter circuit for driving a motor used in a laundry machine such as a washing machine is provided with, for example, an IGBT ( A module formed by integrating a plurality of switching elements, such as an Insulated Gate Bipolar Transistor, is generally used as an IPM (Integrated Power Module).
[0003]
In the current motor drive control, there is a problem that the control accuracy cannot be improved because the current (torque) of the motor cannot be directly controlled. Further, the drive control requires a Hall sensor to detect the rotational position of the rotor constituting the motor, thereby increasing the cost, and mounting the sensor limits the degree of structural freedom. Furthermore, even if a plurality of Hall sensors are mounted, it is difficult to obtain detailed positional information, so that a high-speed control response cannot be obtained.
[0004]
As a technique for solving such a problem, introduction of vector control to drive control of an inverter circuit has been proposed in, for example, Japanese Patent Application No. 2002-27691. FIG. 9 schematically shows a configuration equivalent to that described in Japanese Patent Application No. 2002-27691. The inverter circuit 1 is configured as an IPM 13 by connecting six IGBTs (switching elements) 2a to 2f in a three-phase bridge as described above, and a flywheel diode 3a is provided between the collector and the emitter of each of the IGBTs 2a to 2f. To 3f are connected.
[0005]
The emitters of the lower arm IGBTs 2d to 2f are connected to ground via shunt resistors 4u, 4v, 4w. The common connection point between the two is connected to the control circuit 6 via the amplifier circuit 5.
[0006]
The amplifier circuit 5 includes an operational amplifier and the like, amplifies the terminal voltages of the shunt resistors 4u to 4w, and applies a bias so that the output range of the amplified signal falls on the positive side (for example, 0 to + 5V). The comparison circuit 7 detects an overcurrent in order to prevent the circuit from being destroyed when the upper and lower arms of the inverter circuit 1 are short-circuited.
[0007]
In the inverter circuit 1, a DC voltage of about 280 V obtained by applying a double-wave full-wave rectification to a 100 V AC power supply 8 by a full-wave rectification circuit 9 composed of a diode bridge and two capacitors 10 a and 10 b connected in series. Is applied. The output terminal of the inverter circuit 1 is connected to each phase winding 11u, 11v, 11w of the motor 11.
[0008]
The control circuit 6 detects currents Iu to Iw flowing through the windings 11u to 11w of the motor 11 obtained via the amplifier circuit 5, and based on the current values, the phase θ of the secondary-side rotating magnetic field and the rotational angular velocity ω , And the three-phase current is subjected to orthogonal coordinate conversion and dq (direct-quadrature) coordinate conversion to obtain an excitation current component Id and a torque current component Iq.
[0009]
Then, when a speed command is given from the outside, the control circuit 6 generates current commands Idref, Iqref based on the estimated phase θ, rotational angular speed ω, and current components Id, Iq, and converts them into voltage commands Vd, Vq. Then, orthogonal coordinate conversion and three-phase coordinate conversion are performed. Finally, a drive signal is generated as a PWM signal and output to the windings 11u to 11w of the motor 11 via the gate driver 12.
[0010]
According to the sensorless vector control configured as described above, the motor torque can be directly controlled by the q-axis current component, so that high-precision control can be performed at high speed, and the vibration and noise of the washing machine can be reduced. Can be reduced.
[0011]
However, since a large current flows through the shunt resistors 4u to 4w externally attached to the inverter circuit 1 configured as the IPM 13, the size has to be increased to some extent. In addition, cement may be coated on the outside of the resistor in order to efficiently radiate heat, which occupies a large space on the circuit board, resulting in an increase in cost.
In recent washing machines, there is a strict demand to make the housing as compact as possible and to increase the washing capacity. Therefore, it is desirable to reduce the size of the control circuit board as much as possible.
[0012]
Further, although a single-sided board is generally used for a circuit board, a large current flows through the shunt resistor 4 as described above. Therefore, there is a problem that the number of work steps increases.
[0013]
The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce the area required for a circuit board when performing vector control based on a phase current detected by a shunt resistor, and to reduce the work required. An object of the present invention is to provide a motor drive circuit device of a laundry machine which can suppress an increase in man-hours.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, a motor drive circuit device for a laundry machine according to claim 1 drives a motor of a laundry machine that performs an operation related to washing.
An inverter circuit for applying AC power to each phase winding of the motor;
A shunt resistor for detecting a phase current of the motor is provided between the switching element on the lower arm side and the ground constituting the inverter circuit, and for the purpose of vector control of the motor,
The switching element and the shunt resistor that constitute the inverter circuit are configured as an IC (Integrated Circuit) housed in one package.
[0015]
That is, in an IC in which a plurality of switching elements are housed in a package, a substrate on which circuit elements are arranged, a molding material, and the like have a large heat capacity. In such an IC, a heat dissipation mechanism such as a heat sink is usually added to the outside of the package in order to improve the heat dissipation efficiency of the switching element. Therefore, the total heat capacity is considerably large.
[0016]
Therefore, if a shunt resistor is also added to this configuration, the heat dissipation mechanism can be used for heat dissipation of the shunt resistor, and the size of the shunt resistor can be reduced. Further, it is possible to further reduce the size by increasing the density relating to the mounting of the shunt resistor. In addition, since the mounting operation is not required, the assembly can be easily performed.
[0017]
In this case, it is preferable that the IC includes an amplifier circuit for amplifying a voltage generated in the shunt resistor in the package. With this configuration, the mounting density can be further improved.
[0018]
In this case, it is preferable that the amplifier circuit is configured using an operational amplifier having a slew rate of 0.5 V / μsec or more. That is, since laundry equipment is often installed indoors of a general household, the frequency is often set to, for example, 15 kHz or more for the purpose of avoiding the switching frequency of the inverter circuit from causing harsh noise. . This is a considerably higher frequency compared to a switching frequency of 3 to 5 kHz for an air conditioner, for example.
Accordingly, the speed of the current pulse detected by the shunt resistor is correspondingly increased. Therefore, if the amplifier circuit is configured using an operational amplifier having a slew rate of 0.5 V / μsec or more, it is sufficient for the current detection. can do.
[0019]
In the above case, it is preferable that the IC includes a driver for driving the switching element in a package. With this configuration, the mounting density can be further improved.
[0020]
In addition, it is preferable that the resistance value of the shunt resistor be set between 20 mΩ and 120 mΩ. That is, since the rotation control range of the motor used in the laundry machine is generally quite wide, the dynamic range of the phase current flowing through the motor is also widened. Then, it becomes a problem whether or not the S / N ratio when the motor rotates at a low speed and the current value becomes small is sufficiently ensured. Therefore, it was confirmed that the current detection can be performed without any trouble by setting the resistance value of the shunt resistor between 20 mΩ and 120 mΩ.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, one embodiment in which the present invention is applied to a washing machine as a laundry machine will be described with reference to FIGS. The same parts as those in FIG. 9 are denoted by the same reference numerals, and description thereof will be omitted. Only different parts will be described below. FIG. 1 shows the electrical configuration of the motor drive circuit device of the present embodiment, which is basically the same as that shown in FIG. However, the IPM (IC) 21 used in the motor drive circuit device has an inverter circuit 22, shunt resistors 23u, 23v, 23w, an amplifier circuit 24, a comparison circuit 25, and a gate driver 26 mounted on one substrate. Thus, a hybrid IC is configured.
[0022]
FIG. 2 is a plan view showing a circuit arrangement in the mold package of the IPM 21. In the substrate 27, an insulating layer 28 having a thickness of about 60 μm is disposed on an aluminum base material having a thickness of about 1 mm, and necessary wiring is formed on the insulating layer 28 with a copper foil having a thickness of about 40 μm. Each circuit element is arranged, and the element and the wiring are connected by a bonding wire (neither is shown).
[0023]
That is, the IGBTs (switching elements) 29a to 29f and the diodes 30a to 30f that constitute the inverter circuit 22 are each configured as a single IC chip, and each of the six IGBTs is arranged. For the shunt resistors 23u, 23v, and 23w, for example, a resistor arranged inside the chip resistor is directly arranged on the substrate 27, and is connected to the wiring. Incidentally, the resistance value of the shunt resistor 23 is set to, for example, 50 mΩ.
[0024]
The driver IC section 40 is configured such that the amplifier circuit 24, the comparison circuit 25, and the gate driver 26 are integrally formed as a one-chip IC. Further, in this configuration, the substrate 27 itself acts as a heat sink for the IGBT 29 and the shunt resistor 23, thereby promoting heat radiation of these components.
[0025]
FIG. 3 is a plan view showing the appearance of a DIP (Dual In-Line Package) package in which the IPM 21 is resin-molded. The reason why the arrangement pitch of the leads is partially increased is to ensure insulation between terminals to which a high voltage is applied. When the IPM 21 is mounted on a substrate, a metal heat sink is fixed on the mold package by screwing.
The configuration of the washing machine and the vector control performed by the control circuit 6 are the same as those described in Japanese Patent Application No. 2002-27691.
[0026]
Next, the operation of the present embodiment will be described with reference to FIGS. FIG. 4 shows an example of current data of the motor 11 detected by the control circuit 6 via the amplifier circuit 24, A / D converted and sampled. The amplification factor of the inverting operational amplifier constituting the amplifying circuit 24 is 5, the slew rate is 0.8 V / μsec, and the driving condition of the motor 11 is a case where the no-load dehydrating operation is performed at a rotation speed of 800 rpm. As the current data, a single value, a moving average value for four and a moving average value for eight are plotted, and each is detected as a substantially sinusoidal waveform.
[0027]
On the other hand, FIG. 5 shows a case where the resistance value of the shunt resistor is 10 mΩ and the amplification factor of the inverting operational amplifier is 24, and current data is similarly sampled. In this case, the data value may be out of the sine wave. That is, since the rotation control range of the motor 11 used in the washing machine is generally considerably wide, the dynamic range of the phase current flowing through the motor 11 is also widened. Therefore, if the resistance value of the shunt resistor becomes too small, the S / N ratio when the motor 11 rotates at a low speed and the current value becomes small tends to be insufficient.
[0028]
FIG. 6 shows the rate [%] at which an error occurs when the sampling data deviates from a value indicating an original sine wave when the resistance value of the shunt resistor is changed in the range of 10 mΩ to 200 mΩ, and the shunt resistance. Of heat generation [W]. Here, the “error rate” indicates an average of each data with the error rate being 10% if the true value of the data is 100 V and the sampling data value is 110 V, for example. . That is, as the resistance value increases, the error rate decreases, but the amount of generated heat increases linearly. Then, the error rate starts to increase when the resistance value falls below 50 mΩ, and then increases sharply as the resistance value decreases.
[0029]
From FIG. 6, it was determined that the lower limit of the resistance value allowing the error rate was set to 20 mΩ and the upper limit of the calorific value was set to 120 mΩ, and the resistance value of the shunt resistor was preferably set in the range of 20 mΩ to 120 mΩ. In the present embodiment, the resistance value of the shunt resistor 23 is set to 50 mΩ, which is a value immediately after the falling curve of the error rate and the rising line of the calorific value intersect.
[0030]
FIG. 7 shows the current ISR (a) flowing through the shunt resistor 23, the terminal voltage VSR (b) of the shunt resistor 23, and the amplifier circuit 24 when the lower arm of the IGBT 29 constituting the inverter circuit 22 is turned on. The waveform of the output signal VADCIN (c) is observed with an oscilloscope. Note that the current ISR and the terminal voltage VSR are observed as negative values.
[0031]
FIG. 8 shows the same observation as in FIG. 7 except that the slew rate of the inverting operational amplifier used in the amplifier circuit is 0.3 V / μsec. In the case shown in FIG. 8, the speed of the operational amplifier cannot respond to the switching rate of the IGBT 29, and the waveform of the output signal VADCIN shown in (c) is such that the control circuit 6 cannot sample a correct value. Distorted.
[0032]
As described above, according to the present embodiment, the IGBTs 29a to 29f constituting the inverter circuits 22 for applying AC power to the phase windings 11u to 11w of the motor 11 and the lower arms thereof are connected, and the motor 11 is sensorless. The shunt resistors 23u to 23w for detecting the phase current of the motor 11 for vector control by the method are housed in one package to constitute the IPM 21.
[0033]
That is, the shunt resistor 23 is built in the IPM 21 having a large heat capacity by a heat sink or the like mounted outside the package to radiate the substrate 27, the resin mold material, and the IGBT 29. Larger mechanisms can be utilized. Therefore, the size of the shunt resistor 23 can be reduced. Further, the mounting density around the shunt resistor 23 can be increased to further reduce the size of the motor drive circuit device. In addition, since the mounting operation is not required, assembly can be performed easily.
[0034]
Further, since the shunt resistor 23 is housed inside the IPM 21, the wiring distance between the IGBT 29 and the shunt resistor 23 is significantly reduced as compared with the case where the shunt resistor 23 is mounted outside. As a result, the current detection is less susceptible to noise, so that the resistance value of the shunt resistor 23 can be set to a smaller value.
[0035]
Further, according to the present embodiment, the gate driver 26 for driving the IGBT 29 and the amplifier circuit 24 for amplifying the voltage generated in the shunt resistor 23 are incorporated in the IPM 21, so that the mounting density is further improved. And the size of the motor drive circuit device can be further reduced.
[0036]
Since the amplifier circuit 24 is configured using an operational amplifier having a slew rate of 0.8 V / μsec, the switching frequency of the inverter circuit 22 is set to 15 kHz or more for the purpose of avoiding annoying noise. However, it is possible to sufficiently cope with the detection of the current flowing through the windings 11u to 11w of the motor 11.
[0037]
In addition, since the resistance value of the shunt resistor 23 is set to 50 mΩ, the S / N ratio when the motor 11 rotates at a low speed and the current value becomes small can be sufficiently secured, and the heat generated by the shunt resistor 23 can be secured. The amount can be sufficiently suppressed.
[0038]
The present invention is not limited to the embodiment described above and illustrated in the drawings, and the following modifications or extensions are possible.
The resistance value of the shunt resistor 23 is not limited to 50 mΩ, and if it is set in the range of 20 mΩ to 120 mΩ, the balance between the allowable error rate and the amount of generated heat can be generally kept good.
The slew rate of the operational amplifier constituting the amplifying circuit is not limited to 0.8 V / μsec. If the slew rate is 0.5 V / μsec, there is no problem in current detection even when the switching frequency of the inverter circuit 22 exceeds 15 kHz to some extent. Make sure that.
Further, the above-described resistance value and slew rate may be appropriately changed according to individual designs such as the rating of the motor and the setting of the switching frequency of the inverter circuit.
[0039]
The amplification circuit 24, the comparison circuit 25, and the gate driver 26 may be configured as different IC chips.
The gate driver 26 may be configured outside the IPM 21. Further, the amplification circuit 24 and the comparison circuit 25 may be configured outside the IPM 21.
The IC is not limited to being configured as a hybrid IC, but may be configured as a monolithic IC.
The switching element is not limited to the IGBT 29, but may be a power transistor or a power MOSFET.
The laundry equipment is not limited to a washing machine, and may be applied to a dryer, a washer / dryer, and the like.
[0040]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to the motor drive circuit device of the laundry machine of this invention, the switching element which comprises an inverter circuit, and the shunt resistor for detecting the phase current of the said motor for the purpose of vector control of the motor in one package. And configured as an IC. Therefore, the mechanism of the IC having a large heat capacity can be used for heat dissipation of the shunt resistor, so that the size of the shunt resistor can be reduced. In addition, the density for mounting the shunt resistor can be increased, and the size of the drive circuit device can be further reduced. In addition, since the mounting operation is not required, the assembling can be easily performed.
[Brief description of the drawings]
FIG. 1 is a view showing one embodiment in which the present invention is applied to a washing machine as a laundry machine, showing an electric configuration of a motor drive circuit device. FIG. 2 is a plan view showing a circuit arrangement in a mold package of the IPM. FIG. 3 is a plan view showing the appearance of a DIP package in which an IPM is resin-molded. FIG. 4 is a diagram showing an example of motor current data detected and sampled by a control circuit via an amplifier circuit. FIG. FIG. 4 corresponds to FIG. 4 when the resistance value is 10 mΩ and the amplification factor of the inverting operational amplifier is 24. FIG. 6: The data error rate and the shunt resistance when the resistance value of the shunt resistance is changed in the range of 10 mΩ to 200 mΩ. FIG. 7 is a graph showing the amount of heat generated by the shunt resistor observed by an oscilloscope when the lower arm of the IGBT constituting the inverter circuit is turned on. FIG. 8 shows waveforms of ISR (a), terminal voltage VSR (b), and output signal VADCIN (c) of the amplifier circuit. FIG. 8 shows a case where the slew rate of an operational amplifier used in the amplifier circuit is 0.3 V / μsec. FIG. 9 corresponding to FIG. 9 FIG. 9 corresponding to FIG.
11 is a motor, 11u, 11v, and 11w are windings, 21 is an IPM (IC), 22 is an inverter circuit, 23u, 23v, and 23w are shunt resistors, 24 is an amplifier circuit, 26 is a gate driver, and 29a to 29f are IGBTs ( Switching element).

Claims (5)

A motor drive circuit device for driving a motor of a laundry machine that performs an operation related to washing,
An inverter circuit for applying AC power to each phase winding of the motor;
A shunt resistor for detecting a phase current of the motor is provided between the switching element on the lower arm side and the ground constituting the inverter circuit, and for the purpose of vector control of the motor,
A motor drive circuit device for a laundry machine, wherein the switching element and the shunt resistor forming the inverter circuit are configured as an integrated circuit (IC) housed in one package. 2. The motor drive circuit device for a laundry machine according to claim 1, wherein the IC includes an amplifying circuit for amplifying a voltage generated in the shunt resistor in a package. 3. The motor drive circuit device for laundry equipment according to claim 2, wherein the amplifier circuit is configured using an operational amplifier having a slew rate of 0.5 V / μsec or more. 4. The motor drive circuit device for a laundry machine according to claim 1, wherein the IC includes a driver for driving the switching element in a package. The motor drive circuit device for a laundry machine according to any one of claims 1 to 4, wherein the resistance value of the shunt resistor is set between 20 mΩ and 120 mΩ.

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