JP2018137913A - Motor drive device, and washing machine or washer dryer using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform, at any given value, limiting control of an input current to an inverter circuit in a motor drive device used in a washing machine or the like.SOLUTION: Control means 6 performs speed control to determine applied voltage to a motor 4 according to a motor rotation number and a command rotation number by rotor position detecting means 4a of the motor 4, makes a slow change of the command rotation number, according to a current motor rotation number, when input current to an inverter circuit 3 exceeds a limiting value in a predetermined table, and can prevent the input current to the inverter circuit 3 from becoming excessive without limiting the input current more than necessary.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a motor driving device that drives a motor by an inverter circuit, and a washing machine or a washing dryer using the same.

  In a motor drive device for driving a washing machine or the like, it is necessary to limit the AC input current so that it does not become excessive when an abnormality occurs. Conventionally, a microcomputer that performs drive control of an inverter circuit is insulated from an AC input current line and often has a different GND potential (for example, see Patent Document 1).

  In Patent Document 1, as an inexpensive method for detecting an overcurrent state in a circuit insulated from a microcomputer, a current detection resistor is inserted in series in a line where current is to be detected, and a voltage generated at both ends of the inserted resistor. Discloses a motor driving device and a washing machine including an overcurrent detection device for driving a photocoupler.

JP 2008-122226 A

  However, the above-described conventional overcurrent detection device of the motor drive device requires circuit components such as a current detection resistor and a DC voltage source, and also requires expensive components such as a photocoupler because the GND potential is different. There is a problem that heat generation in the resistance part and loss in the detection resistance part also increase, and there is a problem that a cheaper motor driving device cannot be configured.

  In order to solve the above problems, a motor driving device according to one aspect of the present invention includes a rectifier circuit connected to a power supply, an inverter circuit that converts DC power of the rectifier circuit into AC power, and driven by the inverter circuit. A brushless motor for driving a load such as a washing and dewatering tub, a rotor position detecting means for detecting a rotor position of the brushless motor, a current detecting means for detecting an input current of the inverter circuit, and controlling the inverter circuit Control means, and the control means performs speed control for determining an applied voltage to the brushless motor from the motor rotational speed of the brushless motor and a command rotational speed by the rotor position detecting means, and is detected by the current detecting means. Primary current determination means for referring to a reference value of the input current of the inverter circuit, the primary current determination means According to the motor rotation speed, when the reference value of the input current of the inverter circuit detected by the current detection means exceeds a preset table limit value, the change in the command rotation speed is made gradual. And

  In the primary current determination means, the limit value of the table may be defined by a monotonically decreasing function having a term proportional to the square of the motor rotation speed. .

  With this configuration, it is possible to provide a low-cost motor driving device that can suppress an excessive input current without limiting the input current of the inverter circuit more than necessary without using an expensive primary current detection unit. be able to.

  A current phase detecting means for comparing the motor current estimated from the input current of the inverter circuit detected by the current detecting means with the rotor position detected by the rotor position detecting means, and detecting the phase of the motor current and the induced voltage; The primary current determination means multiplies the current value of the input current of the inverter circuit detected by the current detection means by the cosine of the phase of the motor current and the induced voltage detected by the current phase detection means. The value may be a reference value for the input current of the inverter circuit.

  This configuration limits the input current of the inverter circuit more than necessary even when the phase of the current changes with respect to the induced voltage of the brushless motor, such as field-weakening control used when operating the brushless motor at high speed. Without a brushless motor.

  In addition, a voltage detection means for detecting a DC voltage of the rectifier circuit and a plurality of the tables are provided, the control means compares the voltage detected by the voltage detection means with a predetermined standard value, The limit value of the table may be switched by selectively applying the plurality of tables according to the magnitude relationship.

  With this configuration, even when the power supply voltage fluctuates, it is possible to suppress an excessive input current without limiting the input current of the inverter circuit more than necessary without using an expensive primary current detector. An inexpensive motor drive device can be provided.

  More specifically, the voltage detected by the voltage detection means is compared with a predetermined standard value, and when it is determined that the potential is higher than that, the limit value of the table is the motor rotation speed. A coefficient having a term proportional to the square and having a monotonically decreasing function may be increased.

  With this configuration, even when the power supply voltage fluctuates high, it is possible to suppress an excessive input current without limiting the input current of the inverter circuit more than necessary without using an expensive primary current detector. A low-cost motor drive device can be provided.

  Further, when the voltage detected by the voltage detecting means is compared with a predetermined standard value and determined to be a lower potential, the limit value of the table is proportional to the square of the motor rotation speed. The coefficient of the monotonously decreasing function may be reduced.

  With this configuration, even when the power supply voltage fluctuates low, it is possible to suppress the input current from becoming excessive without limiting the input current of the inverter circuit more than necessary without using an expensive primary current detector. A low-cost motor drive device can be provided.

  The motor drive device of the present invention can limit the primary current to an arbitrary desired range without using an expensive primary current detector, and can suppress an excessive input current. In addition, by changing the limit value of the input current of the inverter circuit according to the command speed, the input current of the inverter circuit is not limited more than necessary at low speed, so the speed decreases due to insufficient torque even at low speed. do not do. In addition, since a primary current detector that requires more expensive parts than in the past is not used, a low-cost motor drive device can be provided.

FIG. 2 is a partial block circuit diagram of the motor drive device according to the first and second embodiments of the present invention. Operation time chart of the motor drive unit Flow chart of limit control of peak value of inverter circuit input current of the motor drive device Flowchart of motor drive subroutine of the motor drive device Flowchart of carrier signal interrupt subroutine of the motor drive device Flowchart of position signal interrupt subroutine of the motor drive device The characteristic figure which shows the function of the limit control table of the peak value of the inverter circuit input current of the motor drive device Flow chart for creating a speed command for the motor drive device Circuit diagram in which the motor driving apparatus according to the third embodiment of the present invention is partly blocked. Flow chart at the time of table switching control by detecting the rectified voltage value of the motor drive device The figure which shows the example of a low electric potential state at the time of the rectification voltage value detection of the motor drive device The figure which shows the example of a standard electric potential state at the time of the rectification voltage value detection of the motor drive device The figure which shows the example of a high potential state at the time of the rectification voltage value detection of the motor drive device The characteristic figure which shows the function of the limit control table of the peak value of the inverter circuit input current of the motor drive device

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

(Embodiment 1)
FIG. 1 is a partial block diagram of the motor drive apparatus according to the first embodiment of the present invention. As shown in FIG. 1, an AC power source 1 (power source) applies an AC voltage to a rectifier circuit 2, and the rectifier circuit 2 converts the DC voltage into a DC voltage by a rectifier 20 and a capacitor 21 and applies the DC voltage to the inverter circuit 3.

  The inverter circuit 3 is constituted by a three-phase full-bridge inverter circuit composed of six power switching semiconductors and an antiparallel diode, and normally includes an insulated gate bipolar transistor (IGBT), an antiparallel diode, its driving circuit, and a protection circuit. It consists of an intelligent power module (IPM). The power switching semiconductor may be composed of a metal oxide semiconductor field effect transistor (MOSFET) in addition to the IGBT. Since the configuration of the inverter circuit 3 is the same as a well-known one, detailed description thereof is omitted.

  The motor 4 is connected to the output terminal of the inverter circuit 3 to drive a load such as a washing blade or a stirring blade (not shown) or a washing / dehydrating tub (not shown) of a washing machine / dryer. The motor 4 is constituted by a brushless motor, and the relative position (rotor position) between the permanent magnet and the stator constituting the rotor (rotor) is detected by the rotor position detecting means 4a. The rotor position detection means 4a is normally composed of three Hall ICs, and detects the output reference signals H1 to H3 at positions at every electrical angle of 60 degrees.

  The current detection means 5 detects an input current of the inverter circuit 3 and uses a shunt resistor that is usually used. It can also be detected by a DC current transformer that can be measured from a low frequency including a DC current, or an AC current transformer.

  As for the motor currents Iu, Iv, and Iw flowing through the phase windings of the motor 4, in the case of a three-phase motor, two-phase currents (for example, Iu and Iv) are obtained, and the remaining from Kirchoff's law (Iu + Iv + Iw = 0) The method for obtaining the one-phase current (Iw) is general, and the same applies to the present embodiment.

  The rotor position detection means 4a detects the rotor position based on the output reference signals H1 to H3, but without using the Hall IC, the rotor position is calculated from the motor phase current and the three-phase motor applied voltage. A detection method may be used (not shown).

  The control means 6 comprises a microcomputer and an inverter control timer (PWM timer) built in the microcomputer, a high-speed A / D conversion circuit, a memory circuit (ROM, RAM), and the like, and from an output signal of the rotor position detection means 4a An electrical angle detection means 60 for detecting an electrical angle, a peak current detection means 61 for detecting a maximum current value from an output signal of the current detection means 5 and a signal of the electrical angle detection means 60, and a three-phase motor application voltage command are created. Storage means 62 for storing sine wave data (sin, cos data) necessary for the operation, and a three-phase motor application voltage for converting a motor application voltage command Vm to the motor 4 into three-phase motor application voltages Vu, Vv, Vw Command creation means 63 and PW for controlling the switching of the IGBT of the inverter circuit 3 according to the three-phase motor applied voltages Vu, Vv, Vw And a like control unit 64.

  Further, setting change means 65 for controlling the start, stop, rotation speed, braking, etc. of the motor 4 according to the stroke, rotation speed detection means 66 for detecting the rotation speed from the output signal of the rotor position detection means 4a, and rotation Motor applied voltage control for performing speed control with reference to the detected rotational speed N detected by the number detecting means 66 and the rotational speed command Ns set by the setting changing means 65 to determine the magnitude of the applied voltage to the motor 4 Means 67.

  The three-phase motor application voltage command creating unit 63 outputs the three-phase motor application voltages Vu, Vv, and Vw to the PWM control unit 64 according to the motor application voltage command Vm input from the motor application voltage control unit 67.

  FIG. 2 shows the waveform relationship of each part during operation of the motor driving device. The edge signals of the output reference signals H1, H2, and H3 of the rotor position detecting means 4a change every 60 degrees, and 360 degrees from each part state signal. The angle divided into 6 can be discriminated. As shown in FIG. 2, a high edge where the induced voltage Ec of the U-phase winding of the motor 4 is 0 V (zero volts) is shown as a reference electrical angle of 0 degrees. The high edge at which the output reference signal H1 changes from low to high has an electrical angle of -30 degrees (or 330 degrees), and has a waveform advanced by 30 degrees from the induced voltage Ec of the U phase winding of the motor. Maximum efficiency can be obtained by making the phase of the U-phase motor current Iu and the induced voltage Ec of the U-phase winding of the motor the same.

  In FIG. 2, the U-phase motor current Iu is slightly advanced from the U-phase winding induced voltage Ec, and the motor applied voltage Vu shows a waveform advanced 30 degrees from the U-phase winding induced voltage Ec. Vc is a sawtooth (or triangular wave) waveform carrier signal generated in the PWM control means 64, and Vu is a sinusoidal U-phase control voltage, which is a PWM signal U that compares the carrier signal Vc and the U-phase control voltage Vu. It is generated in the control means 64 and added as a control signal for the U-phase upper arm transistor of the inverter circuit 3. ck is a synchronizing signal of the carrier signal Vc, and is an interrupt signal when the carrier counter counts up and overflows.

  Coordinate conversion from the stationary coordinate system to the rotating coordinate system, that is, dq conversion, is performed with the electrical angle at which the rotor magnet axis of the motor 4 and the magnetic flux axis of the stator coincided as the d axis, and a reference electrical angle of 0 degrees. 60 detects electrical angles such as 30 degrees, 90 degrees, and 150 degrees from the output reference signals H1, H2, and H3 of the rotor position detecting means 4a, and obtains the electrical angle θ by estimation except every 60 degrees.

  The peak current detector 61 detects the peak value (maximum value) of the inverter input current.

The rotation speed detection means 66 detects the motor rotation speed from the output reference signal H3 of the rotor position detection means 4a, and applies the rotation speed signal to the setting change means 65 and the motor applied voltage control means 67.

  The setting change means 65 (primary current determination means) sets the rotation speed of the motor 4, sets the advance value θs of the applied voltage to the motor according to the rotation speed, and sets the rotation speed command to the motor applied voltage control means 67. Set Ns. Note that H1 and H2 may be used for the output reference signal, respectively, or an average value of rotation speeds obtained from the signals H1 to H3 may be used (not shown).

  The motor applied voltage control means 67 includes a rotational speed comparison means 67a for comparing the detected rotational speed N with the rotational speed command Ns, an error signal ΔN between the detected rotational speed N and the rotational speed command Ns, and a change rate (acceleration) of the rotational speed. ) In accordance with the motor application voltage setting means 67b for controlling the motor application voltage command Vm.

  The motor application voltage setting unit 67b performs so-called rotation speed control and speed minor loop control, in which the motor application voltage command Vm is PI-controlled according to the error signal ΔN. The setting change such as the gain in the PI control is received from the setting change means 65, and will be described according to the flowchart described later.

  The advance value θs of the applied voltage to the motor described above is a signal applied from the setting changing means 65 to the three-phase motor applied voltage command creating means 63. In the case of an embedded magnet motor, the advance value θs of the motor depends on the rotational speed. It is set so that the phase of the motor winding current (Iu, etc.) is advanced from the induced voltage (Ec, etc.).

  In the case of a surface magnet motor, the motor induced voltage (Ec, etc.) and the motor winding current (Iu, etc.) are usually set so that the phase of the motor winding current (Iu, etc.) matches as much as possible. In order to perform field-weakening control (current advance angle) during such high-speed rotation, the angle is set to be greatly advanced.

  In the first embodiment, the current flowing from the AC power supply 1 to the rectifier circuit 2 is limited. In the surface magnet motor, the induced voltage of the motor and the winding current of the motor are set so as to match as much as possible. Therefore, the following description will not be described in particular. A case where the winding current of the motor is positively advanced will be described in a second embodiment described later.

  The three-phase motor applied voltage command creating means 63 calculates the three-phase motor applied voltages Vu, Vv, and Vw from the motor applied voltage command Vm and the advance value θs of the applied voltage to the motor by the following formula 1. In synchronization with the carrier signal, a sinusoidal signal corresponding to the electrical angle θ detected by the electrical angle detection means 60 is applied to the PWM control means 64.

  The operation and action of the motor driving apparatus having the above configuration will be described with reference to FIGS. FIG. 3 is a flowchart showing switching of motor control in the present embodiment. At step 100, motor control for controlling the speed of the motor 4 of the washing machine or the washing / drying machine is started.

  In step 101, a speed command is determined, and in step 102, the current rotational speed is detected. A method for determining the speed command will be described later. Thereafter, in step 103, the peak value of the inverter input current is detected. At the same time, in step 104, the limit value of the inverter input current is acquired by a method described later.

  In step 105, the peak value of the inverter input current obtained from the output signal of the current detection means 5 is set as a reference value of the inverter input current (described as Iinv reference value in the figure), and the limit value of the inverter input current (indicated by Iinv limit value in the figure). If the current reference value is higher than the limit value, the process proceeds to step 107, and if it is lower, the process proceeds to step 106.

  In step 106, the Iinv limit flag is stored as 0 to indicate that the reference value of the inverter input current does not exceed the limit value of the inverter input current. In step 107, the Iinv limit flag is stored as 1 to indicate that the reference value of the inverter input current exceeds the limit value of the inverter input current.

  In step 108, a subroutine process for motor control is performed in accordance with the speed command. Thereafter, in step 109, if the motor control is continuing, the process returns to step 101 and the speed control is continued. When the motor control is finished, the speed control is finished.

  The control of the motor drive subroutine (motor control subroutine) performed in step 108 will be described with reference to FIG. When the motor drive subroutine starts from step 600, the routine proceeds to step 601 where it is determined whether or not there is a carrier signal interrupt. The carrier signal interrupt is executed by an interrupt signal ck that is generated when the carrier counter of the PWM control means 64 overflows. If there is a carrier signal interrupt, the routine proceeds to step 602 and the carrier signal interrupt subroutine is executed. Run.

  FIG. 5 shows a detailed flowchart of the carrier signal interrupt subroutine. The carrier signal interrupt subroutine is started from step 700, and the interrupt signal ck is counted in step 701.

  Next, the routine proceeds to step 702, where the electrical angle detection means 60 calculates the electrical angle θ of the rotor position. The electrical angle θ at the rotor position is obtained by multiplying the separately obtained electrical angle Δθ per carrier signal period by the count value k of the carrier counter k · Δθ every 60 degrees that can be detected by the rotor position detecting means 4a. Estimate by adding φ.

  If the motor 4 has 8 poles, the carrier frequency is 15.6 kHz, and the rotational speed is 900 r / min, the motor drive frequency is 60 Hz, and the count value k of the carrier counter within an electrical angle of 60 degrees is about 43. Therefore, Δθ is about 1.4 degrees. As the motor rotational speed is lower, the count value k within an electrical angle of 60 degrees is higher, and the electrical angle detection resolution in calculation is improved. Therefore, it can be understood that there is no problem even when the rotational speed is low and accuracy is required.

Next, the process proceeds to step 703, and the motor application voltage command Vm and the advance value θs of the application voltage to the motor are called. The process proceeds to step 704, where a three-phase motor application voltage command is created according to the above-mentioned equation 1. The applied voltages Vu, Vv, and Vw are obtained. The three-phase motor application voltage command is generated by performing product-sum operation at high speed using sin θ and cos θ data corresponding to the electrical angle θ of the storage means 62. Next, the process proceeds to step 705, where the PWM control means 64 performs PWM control corresponding to the three-phase motor applied voltages Vu, Vv, Vw, and the process proceeds to step 706 to complete the subroutine and return.

  As explained in FIG. 2, the PWM control compares the sawtooth wave (or triangular wave) carrier signal with the three-phase motor applied voltages Vu, Vv, and Vw corresponding to the U phase, V phase, and W phase. Then, the IGBT on / off control signal of the inverter circuit 3 is generated and the motor 4 is driven in a sine wave. The signals of the upper arm transistor and the lower arm transistor are reversed waveforms, and the conduction ratio of the upper arm transistor is increased. The output voltage increases with a positive voltage. When the conduction ratio of the lower arm transistor is increased, the output voltage increases with a negative voltage.

  When the conduction ratio is 50%, the output voltage becomes zero. When the control voltage is changed in a sine wave shape corresponding to the electrical angle θ, a sine wave current flows. In the case of sine wave drive, when the transistor conduction ratio is set to the maximum value of 100%, the output voltage is maximum and the modulation degree Am is 100%. When the maximum value of the conduction ratio is 50%, the output voltage is minimum and the modulation is performed. The degree Am is called 0%.

  Returning to FIG. 4, after executing the carrier signal interrupt subroutine (step 602), the process proceeds to step 603 to determine whether or not there is a position signal interrupt. When any one of the output reference signals H1, H2, and H3 of the rotor position detecting means 4a changes, an interrupt signal is generated, and the process proceeds to step 604 to execute the position signal interrupt subroutine shown in FIG. As shown in FIG. 2, an interrupt signal is generated every 60 electrical angles.

  Here, the position signal interruption subroutine will be described with reference to FIG. The position signal interruption subroutine is started from step 800, the process proceeds to step 801, and the output reference signals H1, H2, H3 are input to the electrical angle detection means 60 to perform position detection, and then the process proceeds to step 802. Thus, the rotor electrical angle θc is detected. Next, the process proceeds to step 803 where the count value k counted in the carrier signal interrupt subroutine is stored in kc, the process proceeds to step 804, the count value k is cleared, the process proceeds to step 805, and an electrical angle between 60 degrees is obtained. The electrical angle Δθ of one carrier is calculated from the count value kc of the carrier counter.

  Next, the routine proceeds to step 806, where the rotational speed detection means 66 determines whether or not it is an interrupt signal based on the output reference signal H1, and if it is a reference position signal interrupt, the routine proceeds to step 807 and the count value of the rotation period measurement timer is reached. T is stored as a cycle To, the process proceeds to step 808, the count value T of the rotation period measurement timer is cleared, the process proceeds to step 809, and the motor rotation speed N is calculated. Next, the routine proceeds to step 810 to start counting of the rotation period measurement timer, and the routine proceeds to step 811 to end the subroutine and return.

  If the detection resolution of the rotation period measurement timer is set to 8-bit accuracy, the clock becomes 64 μs and the carrier signal can be used as the clock. However, in order to improve the rotation control performance, it is necessary to improve the rotation period detection resolution, and the clock period Needs to be set to 1 to 10 μs. In this case, the microcomputer system clock is divided and used as the clock.

  Although the rotation speed detection method described above has shown the method of calculating | requiring from the period of the output reference signal H1, you may use all the output reference signals H1, H2, and H3. Also, if the carrier signal is a triangular wave, the carrier counter timer cycle is twice that of the sawtooth wave. Therefore, if the triangular wave overflow signal is used as a clock, the resolution is improved. Good.

  Subsequently, the limit control table (Iinv limit table) of the peak value of the inverter input current for obtaining the limit value (Iinv limit value) of the inverter input current in step 104 in FIG. 3 and the speed command generation method in step 101 will be described below. .

  FIG. 7 shows an example of an Iinv limit table for acquiring the limit value (Iinv limit value) of the inverter input current of the motor drive device according to the first embodiment of the present invention. FIG. 7 is a characteristic diagram showing the relationship between the motor rotation speed and the peak value of the inverter input current when the effective value of the current flowing to the rectifier circuit 2 is 7 A when the voltage of the AC power supply 1 is 100 V AC. 7 shows that the effective value of the current flowing to the rectifier circuit 2 can always be controlled to 7 A or less by holding the peak value of the inverter input current on the x-axis side indicating the motor rotation speed from the characteristic curve of FIG. The following formula 2 represents the curve of FIG.

  Equation 2 is expressed by a quadratic curve, but is not limited to this as long as the peak value of the inverter input current monotonously decreases with a power of the motor rotation speed, and is expressed by Equation 2. By limiting the peak value of the inverter input current in the x-axis and y-axis directions from the curve, it is possible to limit the peak value to an arbitrary value without detecting the effective value of the primary current.

  For example, when the motor speed is controlled to 700 rpm, the effective value of the current flowing to the rectifier circuit 2 is controlled to 7 A or less by controlling the peak value of the inverter input current so as not to exceed 2.41 A. Is possible.

  Similarly, when the speed of the motor rotation is controlled to 400 rpm, the effective value of the current flowing to the rectifier circuit 2 is controlled to 7 A or less by controlling the peak of the inverter input current so as not to exceed 3.00 A. Is possible.

  As described above, the inverter input current limit value (Iinv limit value) is acquired in correspondence with the motor rotation speed, and used as a reference when generating the Iinv limit flag.

  Next, creation of a speed command performed in association with the value of the Iinv limit flag will be described.

  The speed command is created by a method of controlling the acceleration so that the peak value of the inverter input current does not exceed the limit value (Iinv limit value) of the inverter input current acquired according to the motor rotation speed by the Iinv limit table described above. . That is, when the peak value of the inverter input current exceeds a preset table limit value (inverter input current limit value), the change in the command rotation speed (rotation speed command Ns) is made moderate.

  FIG. 8 is a flowchart showing a method for creating a speed command. The flowchart at the time of acceleration of a brushless motor is shown for explanation.

  The previous value of the speed command sample cycle (control cycle) is represented by the subscript n-1, and the current value is represented by the subscript n. The current speed command is Ns (n), the previous speed command is Ns (n-1), the current acceleration command is ΔNs (n), the previous acceleration command is ΔNs (n-1), and after the acceleration is finished The target value of speed is Nss, the target value of acceleration is ΔNss, and the increase / decrease value of acceleration is α.

  The speed command is created as follows. In step 300, creation of a speed command is started. In step 301, the Iinv limit flag set in FIG.

  If the Iinv limit flag is 0, that is, if the peak value of the inverter input current does not exceed the setting value (Iinv limit value) of the Iinv limit table described above, the routine proceeds to step 302. In steps 302 to 305, the acceleration increase / decrease amount α is increased within a range not exceeding the acceleration target value ΔNss with respect to the previous acceleration command ΔNs (n−1). Thereafter, in step 307, the speed command Ns (n) is determined.

  If the Iinv limit flag is 1 in step 301, that is, if the peak value of the inverter input current exceeds the set value of the Iinv limit table, the process proceeds to step 306. In step 306, a value obtained by subtracting the acceleration / deceleration increase / decrease value α from the previous acceleration command ΔNs (n−1) is set as the current acceleration command ΔNs (n). Thereafter, in step 307, a speed command Ns (n) is created.

  In Step 307, the current speed command Ns (n) is determined by adding the current acceleration command ΔNs (n) obtained according to the flow in Steps 301 to 306 to the previous speed command Ns (n−1).

  The current speed command Ns (n) and the current acceleration command ΔNs (n) are stored and used as the speed command Ns (n−1) and the acceleration command ΔNs (n−1) when the next speed command is created. The The speed command Ns (n) thus obtained is used as the rotation speed command Ns input from the setting change means 65 to the motor applied voltage control means 67 described above.

  Although illustration is omitted, although the current speed command Ns (n) is determined in step 307, it is necessary to increase the speed command within a range not exceeding the target value Nss of speed after the acceleration is completed.

  In this embodiment, as an example of a method for controlling the acceleration so that the peak value of the inverter input current does not exceed the setting value of the Iinv limit table described above, a method for performing the control using the increase / decrease value α of the acceleration will be described. However, it does not stick to the method of creating acceleration increase / decrease. Similarly, it is also effective to increase or decrease the speed command so that the peak value of the inverter input current does not exceed the setting value of the Iinv limit table described above after shifting to a constant speed.

  The limit control of the peak value of the inverter input current described above makes it possible to control the current to a desired value without detecting the current flowing to the rectifier circuit 2, and the inverter input current can be controlled more than necessary at low speed. Since the limit value can be appropriately changed according to the motor rotation speed without limiting the peak value, it is possible to prevent a problem due to insufficient torque at the time of low rotation.

(Embodiment 2)
In the first embodiment, the limit limiting characteristic of the peak value of the inverter input current is described. However, when the induced voltage of the brushless motor and the current phase of the winding are extremely different, such as field weakening control and current advance angle control. Is not considered. When the brushless motor is controlled at high speed, the induced voltage may approach or exceed the power supply voltage. In such a case, the field-weakening control is performed by greatly advancing the advance value θs of the voltage applied to the motor so that the winding current of the motor is advanced from the induced voltage of the motor in accordance with the rotational speed. When the field weakening control is performed, the winding current of the motor becomes larger than the primary side current. On the other hand, when the brushless motor is driven at a low speed, the advance value θs of the applied voltage is set so that the phase of the winding current of the motor and the induced voltage are substantially the same as described above, and the surface magnet type In the case of this motor, the current is minimum with respect to the torque generated by the motor.

  In the present embodiment, the configuration is such that the primary side current can be limited to a desired value without reducing the peak value of the inverter input current more than necessary even when the induced voltage of the brushless motor and the current phase of the winding are extremely different. Will be described. Hereinafter, a different part from Embodiment 1 is demonstrated, and since it is the same as Embodiment 1 about another structure, description is abbreviate | omitted.

  The electric angle detection means 60 in the circuit diagram in which the motor driving device shown in FIG. 1 is partially blocked is 30 degrees, 90 degrees, 150 degrees, etc. from the output reference signals H1, H2, H3 of the rotor position detection means 4a. The electrical angle is detected, and the electrical angle θ is obtained by estimation except for every 60 degrees. The peak current detection means 61 also has a current phase detection means.

  The current phase β is the phase between the induced voltage of the motor and the motor winding current. The current phase detection means combined with the peak current detection means 61 described above determines the electrical angle θ at the timing of the zero crossing of the motor winding current. It is obtained by detecting.

  The U-phase current is positive when the U-phase upper power switching semiconductor of the inverter circuit 3 and the lower V-phase and W-phase power switching semiconductors are on (the U-phase winding of the motor). Current in the negative direction when the power switching semiconductor on the lower side of the U phase of the inverter circuit 3 and the power switching semiconductor on the upper side of the V phase and the W phase are on. Each can be detected. The same applies to the V phase and the W phase. The electrical angle θ at the time of zero-crossing of the U-phase current becomes the current phase β, which is a value shifted by 120 degrees when using the detection values for the V-phase and W-phase currents.

  The current phase β thus obtained is input from the peak current detecting means 61 (current phase detecting means) to the setting changing means 65, and the value obtained by multiplying the cosine cos β by the peak value of the inverter input current is obtained as the inverter input current. By comparing with the set value (Iinv limit value) of the Iinv limit table as a reference value, the motor 4 can be favorably operated without limiting the current more than necessary.

(Embodiment 3)
In the first embodiment, the limit limiting characteristic of the peak value of a single inverter input current when the power supply voltage is constant has been described. However, since the case where the power supply voltage fluctuates is not considered, the present embodiment In the embodiment, a configuration that can limit the primary current to a desired value without reducing the peak value of the inverter input current more than necessary even when the power supply voltage fluctuates will be described with reference to the drawings.

  FIG. 9 is a partial block diagram of the motor drive apparatus according to the third embodiment of the present invention. In addition to the configuration of the first embodiment, the motor drive device of the present embodiment includes voltage detection means 69 that detects the voltage of the rectifier circuit 2, and the other configurations are the same as those of the first embodiment. is there. Hereinafter, a different part from Embodiment 1 is demonstrated and description is abbreviate | omitted about another structure.

  FIG. 10 illustrates the switching process of the Iinv limit table of the peak value of the inverter input current by the rectified voltage value detection performed by the voltage detection means 69 for each step. In step 200, the voltage Vp of the capacitor 21 of the rectifier circuit 2 is detected, and in step 201, it is compared with a predetermined high-level specified value. In step 201, if the Vp voltage is higher than the high specified value, the process proceeds to step 203, and the Iinv limit table corresponding to the high potential is selected, and if it is low, the process proceeds to step 202.

  In step 202, the lower specified value is compared with the Vp voltage. If the Vp voltage is lower than the lower specified value, the process proceeds to step 204, and the low potential correspondence Iinv limit table is selected. Then, the limit limit table (standard Iinv limit table) of the peak value of the standard inverter input current is selected. The table selected in steps 203 to 205 is set as a limit table for the peak value of the inverter input current.

  The specified value to be compared with the Vp voltage value in steps 201 and 202 will be described with reference to FIGS.

  FIG. 11 shows the voltage waveform (calculated waveform) of the rectified voltage detected by the voltage detection means 69 under the condition that the power supply voltage is 85V. In FIG. 11A, the state of the motor 4 is energized (rotating), the voltage value pulsates from 210V to 225V, and the average value is about 215V. In FIG. 11B, the state of the motor 4 is stopped, the pulsation of the voltage value is small, and the average value is about 235V. When the power supply voltage is 85V, if the motor is rotating, the peak value of the appropriate inverter input current against power supply voltage fluctuation is set by setting a table with 235V or less as the average value and 255V or less when the motor is stopped as the lower specified value. The limit table can be selected.

  Similarly, FIG. 12 shows the voltage waveform (calculated waveform) of the rectified voltage detected by the voltage detecting means 69 under the condition that the power supply voltage is 100 V, which is a standard voltage. In FIG. 12A, the state of the motor 4 is energized (rotating), the voltage value pulsates from 235V to 265V, and the average value is about 255V. In FIG. 12B, the state of the motor 4 is stopped, the pulsation of the voltage value is small, and the average value is about 275V. When the power supply voltage is 100V, if the motor is rotating, set the standard table as an average value of 235V or more and less than 275V, and when stopped, it is 255V or more and less than 295V. The limit table can be selected.

  Similarly, FIG. 13 shows the voltage waveform (calculated waveform) of the rectified voltage detected by the voltage detection means 69 under the condition of the power supply voltage 115V. In FIG. 13A, the state of the motor 4 is energized (rotating), the voltage value pulsates from 285V to 305V, and the average value is about 295V. In FIG. 13B, the state of the motor 4 is stopped, the pulsation of the voltage value is small, and the average value is about 315V. When the power supply voltage is 115 V, the average value of 275 V or more is set when the motor is rotating, and when the motor is stopped, the table is set with a high specified value of 295 V or more. A peak value limit table can be selected.

  FIG. 14 shows the case where the effective value of the current flowing to the rectifier circuit 2 is 7 A when the voltage of the AC power source 1 is in a high voltage condition (AC 115 V), a standard voltage (AC 100 V), and a low voltage condition (AC 85 V), respectively. It is a characteristic view which shows the relationship between a motor rotation speed and the peak value of an inverter input current. By holding the peak value of the inverter input current on the x-axis side indicating the number of revolutions from the respective characteristic curves in FIG. It shows what you can do.

  In the curve of FIG. 14, the curve of the high voltage condition (high potential inverter input current peak value limit control table) is expressed by the mathematical formula 3, the low voltage condition (low potential inverter input current peak value). Expression 4 represents the curve of the limit control table). A curve representing the curve at the time of the standard voltage (the limit control table of the peak value of the inverter input current at the standard potential) is represented by the same formula 2 as in the first embodiment.

  Equations 3 and 4 are expressed by quadratic curves, but the present invention is not limited to this as long as the peak value of the inverter input current monotonously decreases with the power of the motor speed. By limiting the peak value of the inverter input current in the x-axis and y-axis directions from the curve expressed by Equation 4, it is possible to limit to an arbitrary value without detecting the effective value of the primary current. It becomes possible.

  In addition, although the limit control table of the peak value of the inverter input current described above has been described in three ways, the reference value corresponding to the power supply voltage fluctuation may be set in four or more ways. Furthermore, the coefficient of the function that monotonously decreases in proportion to the square of the motor rotation speed may be continuously changed with respect to the power supply voltage fluctuation range.

  The washing machine and the washing / drying machine using the above motor driving device limit the input current of the inverter circuit so that the input current of the inverter circuit does not become excessive when there is an abnormality, and the capacity and the bias of the laundry in the drum driven by the motor. As a result, the motor can be driven by the optimum torque control according to the load that varies depending on the power consumption, and the energy saving performance can be improved. In addition, since the number of rotations of the drum can be controlled finely and efficiently in accordance with various washing, rinsing and drying conditions, a multifunctional and easy-to-use washing machine and washing / drying machine can be provided. In addition, since the circuit configuration of the motor drive device can be simplified and expensive parts such as a photocoupler can be eliminated, an inexpensive washing machine and washing dryer can be provided.

Since the motor drive device according to the present invention can provide a low-cost motor drive device that can prevent the input current from becoming excessive without limiting the peak value of the inverter input current more than necessary, The present invention can be suitably used for a motor driving device of a washing machine and a washing / drying machine in which the secondary current needs to be limited to an arbitrary value.

1 AC power supply
2 Rectifier circuit 3 Inverter circuit 4 Motor (brushless motor)
4a Rotor position detection means 5 Current detection means 6 Control means 60 Electrical angle detection means 61 Peak current detection means 62 Storage means 63 Three-phase motor applied voltage command creation means 64 PWM control means 65 Setting change means (primary current determination means)
66 Rotational speed detection means 67 Motor applied voltage control means 69 Voltage detection means

Claims (7)

A rectifier circuit connected to a power source; an inverter circuit that converts DC power of the rectifier circuit into AC power; a brushless motor that is driven by the inverter circuit and drives a load such as a washing and dewatering tub; and a rotor of the brushless motor Rotor position detecting means for detecting position, current detecting means for detecting input current of the inverter circuit, and control means for controlling the inverter circuit, wherein the control means is the brushless motor by the rotor position detecting means. A primary current determination means for performing speed control for determining an applied voltage to the brushless motor from the motor rotation speed and the command rotation speed, and referring to a reference value of the input current of the inverter circuit detected by the current detection means, The primary current determination means is an inverter detected by the current detection means in accordance with the motor rotational speed. Motor driving apparatus characterized by gradually changing the command rotational speed to exceed the limit value in the table the reference value of the input current of over-capacitor circuit is preset. 2. The motor drive according to claim 1, wherein, in the primary current determination means, the limit value of the table is defined by a monotonically decreasing function having a term proportional to the square of the motor rotation speed. apparatus. Current phase detection means for comparing the motor current estimated from the input current of the inverter circuit detected by the current detection means and the rotor position detected by the rotor position detection means to detect the phase of the motor current and the induced voltage; The primary current determination means is obtained by multiplying the current value of the input current of the inverter circuit detected by the current detection means by the cosine of the phase of the motor current and the induced voltage detected by the current phase detection means, The motor driving apparatus according to claim 1, wherein a reference value of an input current of the inverter circuit is used. A voltage detection means for detecting a DC voltage of the rectifier circuit and a plurality of the tables are provided, and the control means compares the voltage detected by the voltage detection means with a predetermined standard value, and the magnitude relationship thereof. The motor driving device according to claim 1, wherein the limit value of the table is switched by selectively applying the plurality of tables. When the voltage detected by the voltage detection means is compared with a predetermined standard value and determined to be higher than that, the limit value of the table is a term proportional to the square of the motor rotation speed. The motor drive device according to claim 4, wherein the coefficient of the monotonically decreasing function is increased. The voltage detected by the voltage detection means is compared with a predetermined standard value, and when it is determined that the potential is lower than that, the limit value of the table is a term proportional to the square of the motor rotation speed. The motor driving apparatus according to claim 4, wherein a coefficient of a monotonically decreasing function is reduced. A washing machine or a washing dryer using the motor driving device according to any one of claims 1 to 6.

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