JP4817745B2 - Vector control inverter device - Google Patents

Description

  The present invention relates to a vector control inverter device for driving a permanent magnet field motor.

  Various values of driving torque, rotational speed, and rotational direction are required for a motor that drives a rotating tub or a stirring body of a washing machine in accordance with a washing / drying process. For example, a reversible operation with a large driving torque is required in the washing process, and a high-speed rotation with a relatively small driving torque is required in the dehydration process. In such an operation, it is required to control the motor so that it does not burn out due to overload, stop due to a trip, or malfunction of the rotational speed control.

  As a conventional method and method for monitoring the abnormal operation of such a motor, for example, in the case of controlling the voltage of a DC brushless motor, when the motor current exceeds a predetermined threshold, it is temporarily determined that the current is abnormal, After that, there are things that try to restart several times and stop the error if the abnormality reoccurs. In some cases, when the motor current reaches a predetermined threshold, the output voltage is limited so that the motor current does not increase further. In either case, the motor current threshold (upper limit) is set to a constant value.

  Also, many recent washing machines obtain a driving force by driving a DC brushless motor with a vector control inverter. In this case, the motor current value is A / D converted and taken into the microcomputer, and an emergency stop is performed when the value exceeds a threshold value. In addition, control for limiting the current command value of vector control to a predetermined value or less is also performed inside the microcomputer, but the limit value in this case is also usually a fixed value.

  Patent Document 1 discloses an example of a washing machine in which the motor overcurrent detection threshold value is different between when washing and when dehydrating. In the case of this known example, the motor torque is transmitted through the speed reduction mechanism by the clutch switching mechanism during washing in which only the stirring blade is driven. For this reason, abnormal torque may be applied to the speed reduction mechanism when the washing load is large. To prevent this, the overcurrent detection threshold is lowered to the torque limit level of the speed reduction mechanism to protect the speed reduction mechanism. On the other hand, since the motor and the dewatering tank are directly connected by the clutch switching mechanism at the time of dewatering, the overcurrent detection threshold is raised to the demagnetization level of the motor.

  However, any of the above methods has the following drawbacks. That is, in any method, the motor current is controlled to be equal to or less than a certain limit value at the time of washing. At the time of washing, the stirring blade is rotated forward and backward at a constant cycle. The motor repeats the operations of start-up, forward rotation high-speed rotation, stop, start-up, reverse rotation high-speed rotation, stop. In order to protect the motor with one limit value during this operation, it is necessary to set the limit value to a low current value corresponding to high speed rotation.

However, if the limit value of the motor current is set to a constant low current value corresponding to such high speed rotation, the motor current is limited at startup and low speed, and sufficient torque is not generated. For this reason, it takes time to start up, causing a problem that the cleaning power decreases or does not start up properly.
JP 2003-326084 A Japanese Patent Application Laid-Open No. 61-262084

  The present invention has been made in order to solve the problems of the prior art, and the problem is that the vector control inverter device for driving the motor may malfunction due to an increase in the induced voltage accompanying an increase in the rotational speed, or the motor It is an object of the present invention to provide a vector control inverter device that can fully extract the capacity of a motor while preventing an overload of the motor.

In order to solve the above-mentioned problem, the invention according to claim 1 is directed to a d-axis current (Id) parallel to a magnetic flux generated by a permanent magnet. The current flowing through a three-phase permanent magnet motor having a permanent magnet for a field provided on a rotor. ) And q-axis current (Iq) orthogonal thereto, and the current component is controlled independently so as to match each command value and the angular velocity of the rotor is estimated. On the basis of a value obtained by subjecting the deviation between the angular velocity command value (ωr) thus determined and the estimated angular velocity value (ωe) of the rotor to a proportional-integral calculation, the current operation amounts (Idc, Iqc) of the d-axis current and the q-axis current ) And the q-axis current manipulated variable (Iqc) determined by the current manipulated variable determiner and the value thereof as the q-axis current command value (Iqr) The d-axis current manipulated variable (Idc) A command value current command value limiting means (60) for output as (Idr), provided with, said current command value limiting unit, the q-axis current manipulated variable limit value (Iqc), the estimated angular velocity of the rotor The value is reduced as the value (ωe) increases, and the value increases as the d-axis current manipulated variable (Idc) increases in the negative direction .

  If such a limit is added to the q-axis current command value (Iqr) and the limit value is determined according to the circuit constants of the motor, the motor current will be prevented from exceeding the rated value and being overloaded. it can. Further, the angular velocity of the rotor is increased and the induced voltage is also increased, so that a situation in which the motor terminal voltage exceeds the DC voltage (Vdc) supplied to the inverter circuit and the vector control becomes impossible can be prevented.

  When the flux control is performed with the d-axis current manipulated variable (Idc) set to a negative value, the generated induced voltage becomes small. Therefore, the limit value of the q-axis current command value (Iqr) for the same angular velocity may be increased. Thus, if the limit value of the q-axis current command value (Iqr) is increased, a high torque can be generated at the same angular velocity.

According to a second aspect of the present invention, in the vector controlled inverter device according to the first aspect, the limit value of the q-axis current manipulated variable (Iqc) in the current command value limiting means is set as an inverter in the inverter device. The higher the DC voltage (Vdc) applied to the circuit (44), the higher the value.

  If the DC voltage (Vdc) applied to the inverter circuit (44) increases, generation of a higher induced voltage is allowed. Therefore, the limit value of the q-axis current command value (Iqr) for the same angular velocity may be increased. Thus, if the limit value of the q-axis current command value (Iqr) is increased, a high torque can be generated at the same angular velocity.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of a vector control inverter device and a washing machine using the vector control inverter device according to the invention will be described with reference to the drawings. FIG. 1 schematically shows an overall configuration of a vertical washing machine of the present embodiment in a longitudinal sectional view. In the figure, the outer box 2 of the washing machine main body 1 has a rectangular box shape, and a top cover 3 is mounted on the top.

  Inside the outer box 2, a water receiving tank 5 that is an outer tank for receiving dehydrated water is disposed in a state of being elastically supported by an elastic suspension mechanism 6. Inside the water receiving tank 5, a rotating tank 7 serving as a washing tank and a dehydrating tank is rotatably arranged. A large number of dewatering holes 8 are formed in the peripheral wall portion of the rotating tank 7, and water dehydrated from the clothing is discharged into the water receiving tank 5 through the dewatering holes 8 during dehydration. In addition, a balance ring 9 is provided at the upper end of the rotating tub 7 for balancing the rotation of the rotating tub 7 during dehydration. A stirring body 11 is rotatably disposed on the inner bottom of the rotating tub 7.

  A driving mechanism 12 is disposed on the outer bottom of the water receiving tank 5. The drive mechanism 12 includes a motor 13 and a clutch mechanism (not shown). The motor 13 is an outer rotor type three-phase permanent magnet motor, and has a configuration in which a rotor 15 having a permanent magnet for field rotation rotates around a stator 14 having an armature winding disposed in the center. It has become. The stator 14 is fixed to the water receiving tank 5 through the drive mechanism unit base 16, and the rotor 15 is directly connected to the stirring body 11.

  During the “washing” and “rinsing” processes, only the stirrer 11 is driven to rotate forward and backward by the motor 13 by the motor 13. During the “dehydration” process, the rotating tub 7 is connected to the rotor 15 by a clutch mechanism, and is driven to rotate at a high speed in one direction together with the stirring body 11.

A drain port 18 is formed at the bottom of the water receiving tank 5. A drain valve 19 is attached to the drain port 18, and a drain hose 20 is connected to the outlet.
In addition, the top cover 3 is provided with an outer lid 22 that can be folded in half to open and close the laundry inlet on the upper surface, and an operation panel 23 on the upper surface of the front part. A control device 24 is attached to the back side of the operation panel 23. Furthermore, an electrical component 25 such as a water supply mechanism or a warm air unit for drying operation is accommodated and installed on the inner surface of the rear portion of the top cover 3.

  Next, the drive circuit of the motor 13 of the washing machine will be described. The motor 13 is an outer rotor type three-phase permanent magnet motor, and is driven by a sensorless vector control inverter device. FIG. 2 shows a circuit configuration of the vector control inverter device 30. The vector control inverter device 30 includes a current control circuit 31, a rotational position estimation circuit 32, a current command value determination circuit 33, and a DC power supply circuit 34.

  Vector control is a method of controlling the magnetic flux and the generated torque by separating the current flowing through the armature into the magnetic flux direction of the permanent magnet, which is the field, and the component orthogonal thereto, and independently adjusting the components. For the current control, a current value represented by a rotating coordinate system rotating with the rotor, that is, a so-called dq coordinate system is used. Here, the d-axis is a magnetic flux direction created by a permanent magnet attached to the rotor, and the q-axis is a direction orthogonal to the d-axis (a direction advanced by π / 2 in the rotation direction by an electrical angle). Of the current flowing through the armature, the q-axis current Iq is a component that generates rotational torque and is also referred to as torque component current. The other d-axis current Id is a component that generates magnetic flux and is also called a magnetization component current.

  The current control circuit 31 performs control so that the values of the d-axis current Id and the q-axis current Iq of the current that actually flows through the motor 13 coincide with the designated d-axis current command value Idr and q-axis current command value Iqr, respectively. Circuit. The current control circuit 31 includes subtraction circuits 36 and 37, proportional-integral calculation circuits 38 and 39, a dq / αβ coordinate conversion circuit 41, an αβ / UVW coordinate conversion circuit 42, a PWM formation circuit 43, an inverter circuit 44, and a current detection circuit 46. Prepare. The current detection circuit 46 is a circuit that detects the d-axis current Id and the q-axis current Iq of the current actually flowing through the motor 13.

  The current detection circuit 46 includes a UVW current detection circuit 47, a UVW / αβ coordinate conversion circuit 48, and an αβ / dq coordinate conversion circuit 49. The UVW current detection circuit 47 is a circuit that detects currents Iu, Iv, and Iw flowing through the phases (U phase, V phase, and W phase) of the motor 13. The UVW current detection circuit 47 is based on the voltages across the three shunt resistors 54 connected between the ground-side switching element 52 of the three types of half-bridge circuit 51 provided in the inverter circuit 44 and the ground potential GND. Currents Iu, Iv, and Iw are detected. As a circuit configuration of the UVW current detection circuit 47, for example, a circuit described in detail in Patent Document 1 is used.

  The detected currents Iu, Iv, and Iw are converted into equivalent two-phase currents Iα and Iβ by the UVW / αβ coordinate conversion circuit 48. The converted two-phase currents Iα and Iβ are further converted by an αβ / dq coordinate conversion circuit 49 to calculate a d-axis current Id and a q-axis current Iq. α and β are coordinate axes of a biaxial coordinate system fixed to the stator of the motor 13. In the calculation of the coordinate conversion in the αβ / dq coordinate conversion circuit 49, a rotor rotational position estimated value (estimated value of phase difference between α axis and d axis) θe described later is used.

The d-axis current Id and the q-axis current Iq thus obtained are compared with the d-axis current command value Idr and the q-axis current command value Iqr output from a current command value limiting circuit 60 described later in the subtraction circuits 36 and 37, respectively. Thus, deviations ΔId and ΔIq are obtained. Deviations ΔId and ΔIq are subjected to proportional-integral calculation by proportional-integral calculation circuits 38 and 39, and output voltage command values Vd and Vq expressed in the dq coordinate system are calculated. The output voltage command values Vd and Vq are converted into values expressed in the α-β coordinate system by the dq / αβ coordinate conversion circuit 41, and further, the αβ / UVW coordinate conversion circuit 42 converts the phase voltage command values Vu, Converted to Vv and Vw. Note that the rotor rotational position estimation value θe, which will be described later, is also used for calculation of coordinate conversion in the dq / αβ coordinate conversion circuit 41.

  The phase voltage command values Vu, Vv, and Vw are input to the PWM forming circuit 43 to form a pulse drive modulated gate drive signal for supplying a voltage that matches the command value. The inverter circuit 44 is a known inverter circuit composed of three types of half-bridge circuits 51, and is supplied with a DC voltage Vdc from the DC power supply circuit 34. The gate drive signal formed by the PWM forming circuit 43 is given to the gates of the switching elements 52, 53, etc. constituting each half bridge circuit 51, and thereby PWM modulated in accordance with the phase voltage command values Vu, Vv, Vw. A three-phase AC voltage is generated and applied to the armature coil.

  Under such a configuration, the subtractor circuits 36 and 37 and the proportional-integral arithmetic circuits 38 and 39 perform feedback control by proportional-integral calculation, and the d-axis current Id and the q-axis current Iq are d-axis current command values Idr and q, respectively. Adjustment is made to match the shaft current command value Iqr.

  In the process of current control as described above, the value of the rotational position (phase difference between the α axis and the d axis) θ of the rotor during coordinate conversion in the αβ / dq coordinate conversion circuit 49 and the dq / αβ coordinate conversion circuit 41. Need. The value of the rotational position θ can be detected by attaching a rotational position detector such as an encoder to the motor 13, but there are significant problems in view of maintenance and cost. In this embodiment, a method for estimating the rotational position θ without using a sensor is used without using such a rotational position detector.

  The rotational position estimation circuit 32 is a circuit for obtaining an estimated value θe of the rotational position θ of the rotor. The rotational position estimation circuit 32 includes an induced voltage estimation circuit 61, a proportional integration calculation circuit 62, and an integration circuit 63. The induced voltage estimation circuit 61 receives the d-axis current Id, the q-axis current Iq, the d-axis output voltage command value Vd, and the estimated angular velocity value ωe of the rotor. Furthermore, the induced voltage estimation circuit 61 stores the d-axis inductance Ld, the q-axis inductance Lq, and the coil resistance R of the armature coil, which are circuit constants of the motor 13.

The induced voltage estimation circuit 61 uses these input values and circuit constants to calculate an induced voltage estimated value Ed in the d-axis direction generated in the armature coil by the magnetic flux generated by the permanent magnet by the following equation.
Ed = Vd-R.Id-Ld.p.Id + .omega.e.Lq.Iq (1) where p is a differential operator.

  The induced voltage estimated value Ed in the d-axis direction thus calculated is input to the proportional-plus-integral calculation circuit 62 and subjected to proportional-integral calculation, and the result is output as the estimated angular velocity value ωe of the rotor. The angular velocity estimated value ωe is integrated by the integrating circuit 63, and the value is output as the rotational position estimated value θe.

  The rotational position estimated value θe is used for coordinate conversion in the αβ / dq coordinate conversion circuit 49 and the dq / αβ coordinate conversion circuit 41 as described above. The estimated angular velocity value ωe is given to the induced voltage estimating circuit 61 and used for calculating the induced voltage estimated value Ed according to the equation (1). The estimated angular velocity value ωe is also given to a current operation amount determination circuit 65 described later.

  By the way, ωe used for the calculation of the right side of the equation (1) is an estimated value of the angular velocity of the rotor, not the actual angular velocity ω. Further, the d-axis current Id and q-axis current Iq on the right side of the equation (1) are values calculated using the rotational position estimated value θe, and the rotational position estimated value θe itself also integrates the angular velocity estimated value ωe. This is the value obtained by Further, the d-axis output voltage command value Vd on the right side of the equation (1) and the q-axis output voltage command value Vq that does not appear in the equation (1) are similarly applied to each phase voltage using the rotational position estimation value θe. Command values Vu, Vv, and Vw are calculated. Based on the value, a voltage is generated by the inverter circuit 44 and applied to the armature coil. That is, all variables other than the circuit constants in the equation (1) are affected by the estimated angular velocity value ωe.

  Ed on the left side of the equation (1) means a component of the induced voltage in the d-axis direction. The induced voltage is a voltage generated by interlinking the magnetic flux generated by the permanent magnet with the armature coil, and should be generated only on the q axis and not on the d axis. Therefore, if the estimated angular velocity value ωe exactly matches the actual angular velocity ω, the induced voltage estimated value Ed in the d-axis direction calculated on the right side of the equation (1) should be zero. That the value does not become zero means that the estimated angular velocity value ωe used in the calculation has an error with respect to the actual angular velocity ω.

  In other words, if the estimated angular velocity value ωe is adjusted so that the value of Ed calculated on the right side of the equation (1) becomes zero, the estimated angular velocity value ωe when it becomes zero becomes the actual angular velocity ω. It means that they match. The proportional-integral operation circuit 62 adjusts the estimated induced voltage Ed in the d-axis direction to zero. If the induced voltage estimated value Ed converges to zero by the adjustment operation of the proportional-integral arithmetic circuit 62, the angular velocity estimated value ωe, which is the output of the proportional-integral arithmetic circuit 62 at that time, becomes a value that matches the actual angular velocity ω. In the present embodiment, by using the induced voltage estimation circuit 61 that performs such an operation, the actual angular velocity ω of the rotor and the estimated angular velocity ωe that matches the value of the rotor position θ are obtained without using the rotational position detector. An estimated rotational position value θe is obtained.

  Next, the configuration and operation of the current command value determination circuit 33, which is a feature of the present invention, will be described. The current command value determining circuit 33 includes a current operation amount determining circuit 65 and a current command value limiting circuit 60. The current manipulated variable determining circuit 65 is a circuit that compares the angular velocity estimated value ωe with the angular velocity command value ωr output from the microcomputer 64 and forms the d-axis and q-axis current manipulated variables according to the comparison result. The current command value limit circuit 60 is a limiter circuit that limits the current operation amount formed by the current operation amount determination circuit 65. The current manipulated variable formed by the current manipulated variable determining circuit 65 is limited in magnitude by the current command value limiting circuit 60, so that the values of the d-axis current command value Idr and the q-axis current command value Iqr are finally changed. It is determined.

  The current operation amount determination circuit 65 includes a subtraction circuit 66, a proportional integration operation circuit 67, and an operation amount distribution circuit 68. The subtraction circuit 66 calculates a deviation Δω between the angular velocity command value ωr output from the microcomputer 64 and the estimated angular velocity value ωe. An operation panel 23 (see FIG. 2) is connected to the microcomputer 64, and operating conditions for the washing machine are input. The microcomputer 64 determines the rotational speed of the motor 13 at each time of each process according to the input operation condition, and outputs it as an angular speed command value ωr.

  The deviation Δω that is the output of the subtraction circuit 66 is input to the proportional-integral calculation circuit 67. The proportional integration calculation circuit 67 performs a predetermined proportional integration calculation on the input deviation Δω and outputs the result as a motor current manipulated variable Ic. This motor current manipulated variable Ic is a motor current manipulated variable for making the deviation Δω close to zero. The operation amount distribution circuit 68 forms an operation amount Idc for the d-axis current and an operation amount Iqc for the q-axis current based on the motor current operation amount Ic.

  The method of forming the d-axis current manipulated variable Idc and the q-axis current manipulated variable Iqc based on the value of the motor current manipulated variable Ic is determined according to a predetermined rule according to the desired motor operating conditions (rotational speed, generated torque, etc.). The In the “washing” process, for example, the d-axis current manipulated variable Idc is always zero, and the motor current manipulated variable Ic is directly used as the q-axis current manipulated variable Iqc. When not limited by the current command value limit circuit 60, the d-axis current manipulated variable Idc that is zero becomes the d-axis current command value Idr as it is, and the q-axis current manipulated variable Iqc equal to the motor current manipulated variable Ic remains as q-axis. The current command value Iqr is output to the current control circuit 31.

  In this case, the torque generated by the motor 13 is proportional to the motor current manipulated variable Ic which is the q-axis current command value Iqr. When the saliency of the motor 13 is weak, the d-axis current Id does not contribute to torque generation. Therefore, such a method of determining the current command value that does not flow the d-axis current Id is efficient with a minimum current for the same generated torque.

  On the other hand, in the “dehydration” step, the motor 13 is required to rotate at high speed. When the rotation speed of the motor 13 is increased, the induced voltage due to the armature linkage magnetic flux of the permanent magnet of the rotor is also increased in proportion thereto, and the terminal voltage of the motor 13 is increased. The terminal voltage must not exceed the power supply voltage (the output voltage Vdc of the DC power supply circuit 34). For this reason, in the “dehydration” step, flux-weakening control is performed.

  In order to perform the flux weakening control, the d-axis current Id is set to a negative value. Therefore, the operation amount distribution circuit 68 forms the current operation amount so that the d-axis current operation amount Idc is a negative constant value and the motor current operation amount Ic is directly used as the q-axis current operation amount Iqc. When not limited by the current command value limit circuit 60, the negative d-axis current manipulated variable Idc is directly used as the d-axis current command value Idr and is equal to the motor current manipulated variable Ic. Is directly output to the current control circuit 31 as the q-axis current command value Iqr.

  In this way, the negative d-axis current Id flows by the d-axis current command value Idr which is a negative constant value, and the magnetic flux in the d-axis direction is reduced. As a result, the induced voltage is reduced and the increase in the terminal voltage of the motor 13 is suppressed, so that the motor 13 can be rotated at a high speed, and as a result, dehydration can be performed efficiently.

  Information regarding what process the washing machine is currently in and what operation is required of the motor 13 is constantly informed from the microcomputer 64 to the operation amount distribution circuit 68. The manipulated variable distribution circuit 68 receives the information, and if it follows a predetermined rule, the d-axis current manipulated variable Idc is set to zero, and the q-axis current manipulated variable Iqc is the motor current manipulated variable Ic that is the output of the proportional integral calculating circuit 67. In some cases, the d-axis current manipulated variable Idc is set to a negative constant value so that the q-axis current manipulated variable Iqc is equal to the motor current manipulated variable Ic. Change the way Iqc is formed.

  In this way, the d-axis current manipulated variable Idc and the q-axis current manipulated variable Iqc are formed, the d-axis current command value Idr and the q-axis current command value Iqr are determined through the current command value limiting circuit 60, and the current control circuit 31. Given to. The current control circuit 31 performs control to supply the motor 13 with a current that matches the commanded value as described above. As a result, the angular velocity ω of the rotor is estimated, and the estimated value ωe is fed back to the current manipulated variable determining circuit 65. The subtraction circuit 66 and the proportional-integral calculation circuit 67 in the current manipulated variable determination circuit 65 perform a control operation so that the fed back angular velocity estimated value ωe converges to the angular velocity command value ωr output from the microcomputer 64. By such a series of speed feedback control, the angular speed ω of the motor 13 is matched with the angular speed command value ωr from the microcomputer 64.

  Next, the current limit value of the current command value limit circuit 60 will be described. In the present embodiment, the current of the motor 13 is limited so as to satisfy the following two conditions. The first limiting condition is that the current of the motor 13 is limited to the maximum rated current Im or less, and the second limiting condition is that the terminal voltage (voltage expressed in the dq coordinate system) Va of the motor 13 is a DC power supply. It is limited to the DC voltage Vdc or less supplied from the circuit 34 to the inverter circuit 44.

  The first limiting condition is a natural condition for preventing the motor 13 from burning out. The second restriction condition is a condition for causing the sensorless vector control inverter device 30 to normally perform the control operation. If the terminal voltage Va of the motor 13 exceeds the DC voltage Vdc supplied to the inverter circuit 44, the current control circuit 31 cannot make the motor currents Id and Iq coincide with the current command values Idr and Iqr. That is, the vector control does not function.

  In the present embodiment, the angular velocity ω and the rotational position θ of the motor 13 are estimated without a sensor. In order for the estimated values to be accurate, it is a requirement that the detected values of the d-axis current Id and the q-axis current Iq match the d-axis current command value Idr and the q-axis current command value Iqr, respectively. Therefore, when the terminal voltage Va exceeds the DC voltage Vdc and the current control circuit 31 does not operate normally, the angular velocity estimated value ωe and the rotational position estimated value θe are also different from the actual values. The estimated rotational position value θe is used for coordinate conversion in the dq / αβ coordinate conversion circuit 41 and the αβ / dq coordinate conversion circuit 49 in the current control circuit 31. If the rotational position estimated value θe is different from the actual value, the calculation of the coordinate conversion becomes inaccurate. If the coordinate conversion becomes inaccurate, the operation of the current control circuit 31 also becomes abnormal. As a result, a vicious circle is chained and the current control circuit 31 becomes inoperable. Therefore, from this point, it is important to limit the terminal voltage Va to the supply DC voltage Vdc or less to the inverter circuit 44.

The first limiting condition is expressed by the following equation when the maximum rated current is Im.
(Id ² + Iq ² ) ^1/2 ≦ Im (1) The second limiting condition can be expressed as follows by replacing it with the condition of the induced voltage.
((Ld · Id + Ψa) ² + (Lq · Iq) ² ) ^1/2 ≦ (Vdc−Ra · Im) / ω (2) where Ld is the d-axis inductance, Lq is the q-axis inductance, and Ra is the coil Resistance, Ψa is an armature flux linkage by a permanent magnet, and ω is an angular velocity.

When the d-axis current Id is zero, the range of the value of the q-axis current Iq that satisfies the expressions (1 ) and (2) is the range below the straight line (1 ) and the curve (2) in the graph of FIG. Become. The horizontal axis is the angular velocity ω. In addition, the straight line (1) in a figure is a straight line when the equal sign of (1) Formula is materialized, and a curve (2) is a curve when the equal sign of (2) Formula is materialized.

  In the current command value limiting circuit 60 of the present embodiment, q in relation to the estimated angular velocity value ωe so that the expressions (1) and (2) are established with some allowance and the calculation of the current limit value is simplified. The limit value of the shaft current command value Iqr is set as shown by the broken line (3) in FIG. That is, the limiting current value is a constant value in a range of a predetermined first angular velocity ω1 or less, and the limiting current value is linearly increased as the angular velocity ω increases in a range of the angular velocity ω1 or more and the second angular velocity ω2 or less. It is set to a constant value at the second angular velocity ω2 or higher. Since the actual angular velocity ω cannot be grasped, the current limit value at that time is determined for the angular velocity estimated value ωe instead.

  FIG. 4 illustrates the current limiting operation in the “washing” process of the washing machine by the vector control inverter device 30. In the “washing” step, since the motor 13 needs to rotate forward and reverse at regular intervals, the microcomputer 64 outputs an angular velocity command value ωr as shown in (1) of FIG. At this time, a rotational torque having a curve as shown in FIG. 4B is generated in the motor 13 by the speed feedback control described above. Considering the case where the saliency of the motor 13 is weak, since the motor torque and the q-axis current Iq are substantially proportional, the q-axis current Iq also draws the same curve as (2) in FIG. A large current flows between times t1 and t2, which is the acceleration period from the start of startup to the steady rotational speed, and the current decreases during the period between times t2 and t3 when the steady speed is reached. A large current flows in the reverse direction between times t3 and t4, which is a deceleration period. The absolute value of the q-axis current Iq between time t1 and time t4 from start to stop draws a curve as shown in (3) of FIG. Further, the detected angular velocity estimated value ωe draws a curve as shown in (4) of FIG.

  Since the estimated angular velocity value ωe changes as shown in FIG. 4 (4), the current command value limit circuit 60 changes the limit value of the q-axis current command value Iqr as shown in the limit value curve in FIG. 4 (5). Let That is, the limit value is set to a large value at times t1 to t2 during the acceleration period and when the value of the angular velocity ω is small. Accordingly, a large current is allowed to flow during this period, and a large starting torque can be generated. However, since the q-axis current manipulated variable Iqc is limited to a predetermined value, it is possible to prevent a current exceeding the rated value from flowing.

  At times t2 to t3, which are steady rotational speeds, the limit value is set low because the value of the angular speed ω is large. For this reason, the angular velocity ω increases for some reason, the induced voltage of the motor 13 also increases, and even if the terminal voltage exceeds the DC voltage Vdc supplied to the inverter circuit 44, the q-axis current command value Iqr is limited, so the terminal voltage Is prevented from exceeding the DC voltage Vdc. Therefore, the vector control inverter device 30 is prevented from malfunctioning.

  Thus, in the vector control inverter device 30 of the present embodiment, the broken line (3) in FIG. 3 indicates the q-axis current manipulated variable Iqc output from the current manipulated variable determining circuit 65 in the current command value limiting circuit 60. Imposes such a current limit (current limit). Therefore, even under various operating conditions, the current of the motor 13 is controlled within the rated value, and the terminal voltage of the motor 13 is controlled so as not to exceed the DC voltage Vdc supplied to the inverter circuit 44. As a result, the motor 13 is prevented from being overloaded and the vector controlled inverter device 30 is prevented from malfunctioning.

(Modified embodiment)
The above embodiment may be modified as follows.
(1) In the above-described embodiment, the limit value of the q-axis current command value Iqr is set to a constant value in the range of the first angular velocity ω1 or less, but the first angular velocity ω1 and the second The limit current value may decrease linearly as the angular velocity ω increases as in the range between the angular velocity ω2 (so that the limit current value increases linearly as the angular velocity ω decreases). . That is, as indicated by a broken line (3-1) in FIG. 5, a straight line between the angular velocities ω1 and ω2 in the broken line (3) in FIG.

  The range below the first angular velocity ω1 in the embodiment is a low angular velocity, and the angular velocity at the start of the start of the motor falls within this range. The limit value of the q-axis current command value Iqr in this range is determined by the motor rating. By the way, the burnout of the motor is determined by the magnitude of the flowing current and its duration, and if the duration is short, a current larger than the current rating during high-speed continuous rotation is allowed. Accordingly, since it is considered that the operation in the range of the first angular velocity ω1 or less is only at the start of activation and the duration is short, the current limit value in that range may be a high value.

  In this modified embodiment, the limit value can be set to a high value as a curve that rises linearly as the angular velocity decreases even in the low angular velocity range equal to or lower than the first angular velocity ω1 in the above-described embodiment. It is. Even in this case, since the operation duration time at the low angular velocity is short, the motor can be prevented from being burned out. If the current limit value in the low angular velocity range is increased in this way, the starting torque is increased and the starting time can be shortened.

(2) The value of the q-axis current Iq that satisfies the expression (2) is allowed to be higher than the zero value when the d-axis current Id is a negative value (curves (2), (2 in FIG. 6). -1)). Therefore, when the negative d-axis current Id is flowed to perform the flux-weakening control as in the “dehydration” step, the limit value of the q-axis current command value Iqr may be set higher. For example, when the limit value curve when the d-axis current Id is zero is as shown by the broken line (3-1) in FIG. 6, when the d-axis current Id is negative, the broken line (3-2) Move the polygonal line (3-1) to the higher side. Thus, if the limit value of the q-axis current command value (Iqr) is increased, a high torque can be generated at the same angular velocity.

(3) The DC voltage Vdc supplied from the DC power supply circuit 34 to the inverter circuit 44 varies depending on the voltage of the commercial power supply 70. According to the equation (2), the higher the DC voltage Vdc, the higher the q-axis current Iq is allowed (see curves (2) and (2-2) in FIG. 7). Therefore, the limit value of the q-axis current command value Iqr may be set higher depending on the value of the DC voltage Vdc. For example, the value of the DC voltage Vdc is a limit value curve for 100V if it was intended to show to the lines (3-1) of FIG. 7, when the value of the dc voltage Vdc becomes 110V is 7 The broken line (3-1) is moved higher as the broken line (3-3). Thus, if the limit value of the q-axis current command value (Iqr) is increased, a high torque can be generated at the same angular velocity.

It is an example of the longitudinal cross-sectional view of a washing machine. 3 is a circuit configuration diagram of a vector control inverter device 30. FIG. It is a figure explaining the current limiting curve of the current command value limiting circuit. It is explanatory drawing of the electric current limiting operation | movement in a "washing" process. It is a figure explaining the other current limiting curve of the current command value limiting circuit. It is a figure explaining the current limiting curve in the flux weakening control. It is a figure explaining the current limiting curve when direct-current voltage Vdc fluctuates.

Explanation of symbols

  In the drawings, 1 is a washing machine body, 13 is a motor, 14 is a stator, 15 is a rotor, 30 is a vector control inverter device, 31 is a current control circuit, 32 is a rotational position estimation circuit, and 33 is a current command value determination circuit. , 44 is an inverter circuit, 46 is a current detection circuit, 61 is an induced voltage estimation circuit, 60 is a current command value limiting circuit (current command value limiting means), 65 is a current manipulated variable determining circuit (current manipulated variable determining means), Id Is the d-axis current, Idc is the d-axis current manipulated value, Idr is the d-axis current command value, Iq is the q-axis current, Iqc is the q-axis current manipulated value, Iqr is the q-axis current command value, ω1 is the first angular velocity, ω2 is a second angular velocity, ωe is an estimated angular velocity value, ωr is an angular velocity command value, Vdc is a DC voltage, and Δω is an angular velocity deviation.

Claims (2)

A current flowing through a three-phase permanent magnet motor having a permanent magnet for a field provided on a rotor is separated into a d-axis current (Id) parallel to the magnetic flux generated by the permanent magnet and a q-axis current (Iq) orthogonal thereto. In the vector control inverter device that controls the current components independently so as to match the respective command values and estimates the angular velocity of the rotor,
Based on a value obtained by subjecting the deviation between the commanded angular velocity command value (ωr) and the estimated angular velocity value (ωe) of the rotor to a proportional-integral operation, the current manipulated variables (Idc, Current operating amount determining means (65) for determining Iqc);
The magnitude of the q-axis current manipulated variable (Iqc) determined by the current manipulated variable determining means is limited, the value is set as the q-axis current command value (Iqr), and the d-axis current manipulated variable (Idc) is set as d. Current command value limiting means (60) for outputting each as a shaft current command value (Idr),
Said current command value limiting means, the limiting value of the q-axis current manipulated variable (Iqc), the angular velocity estimate of the rotor (.omega.e) decreases as the increase, the d-axis current manipulated variable (Idc) is negative A vector control inverter device characterized in that the higher the value in the direction, the higher the value . 2. The vector control inverter device according to claim 1, wherein the limit value of the q-axis current manipulated variable (Iqc) in the current command value limiting means is a DC voltage (Vdc) applied to an inverter circuit (44) in the inverter device. ), The vector control inverter device is characterized in that the higher the value, the higher the value.

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