JP2020005437A - Motor drive device - Google Patents

Abstract

To provide a motor drive device that can suppress a harmonic component at low cost without using a sensor having high resolution, a microcomputer having high computing power, or the like.SOLUTION: A motor drive device 1 comprises an inverter 30, a controller 50, and Hall sensors 62, 64 and 66. A controller 50 generates an output pattern of the inverter 30 according to detection signals of the Hall sensors 62, 64 and 66. Then, the controller 50 corrects a rectangular-wave shaped voltage command of the inverter 30 generated based on the output pattern to a sine-wave shaped voltage command using a correction factor prepared previously, and controls the inverter 30 on the basis of the corrected sine-wave shaped voltage command.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a motor drive device, and more particularly, to a technique for controlling an inverter that drives a motor.

  As a motor control method, a composite magnetic flux generated by the U-phase coil, the V-phase coil, and the W-phase coil by switching two layers to be energized among the U-phase, V-phase, and W-phase every 60 degrees (electric angle). The so-called "120-degree energization control method" is known in which the direction is switched according to the rotational position of the rotor to rotate the rotor.

  For example, Japanese Patent Application Laid-Open No. 2012-147561 (Patent Document 1) discloses an inverter control system using such a 120-degree conduction control method. In this inverter control system, a 120-degree conduction pattern corresponding to the electric angle of the motor is generated, and the generated 120-degree conduction pattern and a PWM (Pulse Width Modulation) signal generated based on the magnitude of the inverter input current. Are logically synthesized to generate a gate signal of a switching element included in the inverter (see Patent Document 1).

JP 2012-147561 A

  The 120-degree conduction control method switches the conduction pattern every 60 degrees (electrical angle), and the voltage generated by the inverter and applied to the motor is a rectangular wave voltage according to the conduction pattern. Since such a rectangular wave voltage contains many harmonic components, it causes motor noise and vibration.

  As a control method for solving the above problem, a so-called “vector control method” in which a sine wave voltage is generated using a rotational position sensor having a high resolution such as an optical encoder or a resolver is known. However, such sensors with high resolution are expensive. Further, in the vector control, a microcomputer having a high calculation capability must be used because the calculation amount is large, and this also increases the hardware cost.

  The present invention has been made in order to solve such a problem, and an object of the present invention is to provide a motor drive capable of suppressing a harmonic component at a low cost without using a sensor having a high resolution or a microcomputer having a high computing ability. It is to provide a device.

  A motor drive device according to the present invention includes: a position detection unit for detecting a rotor position of a motor for each predetermined rotation angle; an inverter for driving the motor; and a control device for controlling the inverter according to a detection signal of the position detection unit. Prepare. The control device generates an output pattern of the inverter for each predetermined rotation angle according to the detection signal of the position detection means. Then, the control device corrects the output command of the rectangular-wave inverter generated based on the output pattern into a sine-wave or triangular-wave output command using a correction coefficient prepared in advance, and outputs the corrected output command. To control the inverter based on

  In this motor driving device, a rectangular output command generated based on an output pattern for each predetermined rotation angle is corrected to a sine or triangular output command using a correction coefficient prepared in advance. Then, since the inverter is controlled based on the sine-wave or triangular-wave output command, harmonics as in the case of rectangular wave drive are suppressed, and noise and vibration of the motor are suppressed. In addition, since a sine-wave or triangular-wave output command is generated by using a correction coefficient prepared in advance, a simple, high-resolution sensor or a microcomputer with a high computing capability, such as a vector control method, is not used. A sinusoidal or triangular output command can be generated by the method.

  Preferably, a correction coefficient is prepared for each of the output patterns. The control device acquires a switching time of the output of the position detecting means that switches at every predetermined rotation angle. Then, the control device outputs an output command in the second pattern based on the switching time acquired in the first pattern of the output patterns and a correction coefficient in the second pattern following the first pattern. to correct.

  Preferably, the control device generates a rectangular wave voltage command for the inverter based on the output pattern and the rotation speed of the motor. Then, the control device generates a sine-wave or triangular-wave inverter voltage command by multiplying the rectangular wave voltage command by the correction coefficient for each output pattern.

  Preferably, the position detecting means includes a plurality of Hall sensors.

  According to the present invention, it is possible to provide a motor drive device capable of suppressing harmonic components at low cost without using a sensor having a high resolution or a microcomputer having a high calculation capability.

1 is an overall configuration diagram of a motor driving device according to an embodiment of the present invention. FIG. 2 is a functional block diagram illustrating a configuration of a portion related to speed control of a controller illustrated in FIG. 1. It is a waveform diagram of the output signal of a Hall sensor. FIG. 7 is a waveform diagram illustrating a rectangular wave voltage command generated by a voltage command generation unit and a sine wave voltage command corrected by a sine wave correction unit. FIG. 6 is a diagram illustrating an example of a map of a correction coefficient used in the sine wave correction unit. It is a waveform diagram of the voltage command in the conventional 120 degree energization control. 9 is a flowchart illustrating an example of a processing procedure executed by a controller. FIG. 11 is a diagram illustrating an example of a comparison result between a processing time when the control method according to the present embodiment is applied and a processing time when vector control is applied as a comparative example. It is a waveform diagram of the voltage command in a modification. FIG. 14 is a diagram illustrating an example of a correction coefficient map according to a modification.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding portions have the same reference characters allotted, and description thereof will not be repeated.

  FIG. 1 is an overall configuration diagram of a motor driving device according to an embodiment of the present invention. Referring to FIG. 1, motor drive device 1 includes a DC power supply 10, a capacitor 20, an inverter 30, a controller 50, and Hall sensors 62, 64, and 66.

  DC power supply 10 supplies DC power to inverter 30. The DC power supply 10 is, for example, a power storage element that stores power, and includes a power storage element such as a secondary battery or an electric double layer capacitor. The capacitor 20 is connected between the pair of power lines on the DC side of the inverter 30, and reduces noise on the DC side (input side) of the inverter 30.

  Inverter 30 includes switching elements Sw1 to Sw6. A diode is connected in anti-parallel to each of the switching elements Sw1 to Sw6. The switching elements Sw1 and Sw2 form a U-phase upper arm and a U-phase lower arm, respectively. The switching elements Sw3 and Sw4 form a V-phase upper arm and a V-phase lower arm, respectively. The switching elements Sw5 and Sw6 constitute a W-phase upper arm and a W-phase lower arm, respectively.

  The connection node between the switching elements Sw1 and Sw2 is connected to the U-phase coil of the motor 40. A connection node between the switching elements Sw3 and Sw4 is connected to the V-phase coil of the motor 40, and a connection node between the switching elements Sw5 and Sw6 is connected to the W-phase coil of the motor 40 (each phase coil is shown in the drawing). Zu).

  Inverter 30 receives DC power from DC power supply 10 and drives motor 40 based on gate signals G1 to G6 received from controller 50. More specifically, the switching elements Sw1 to Sw6 are turned on / off based on the gate signals G1 to G6, and the motor 40 is driven by applying a voltage from the inverter 30 to each phase coil of the motor 40.

  The motor 40 is a synchronous motor, specifically, a brushless DC motor. The rotor of the motor 40 is provided with a permanent magnet (not shown). Based on the rotor position detected by the Hall sensors 62, 64, 66, the energization of the U, V, W phase coils is switched by the inverter 30. Thereby, the direction of the synthetic magnetic flux generated by each phase coil is switched according to the rotor position, and the rotor rotates. The attachment of the permanent magnet to the rotor may be of an embedded type or a surface type.

  The Hall sensor 62 is arranged between the W-phase coil and the U-phase coil at a rotation angle, the Hall sensor 64 is arranged between the U-phase coil and the V-phase coil at a rotation angle, and the Hall sensor 66 is rotated at a rotation angle. It is arranged at a corner between the V-phase coil and the W-phase coil.

  The Hall sensors 62, 64, and 66 output signals Hu, Hv, and Hw, respectively. Each of the signals Hu, Hv, and Hw switches between an H (logic high) level and an L (logic low) level due to a change in the magnetic pole of the rotor accompanying rotation of the rotor. By combining the signals Hu, Hv, Hw from the Hall sensors 62, 64, 66, the rotor position of the motor 40 can be detected.

  The controller 50 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and an input / output port for inputting / outputting various signals. Not shown). The CPU expands a program stored in the ROM into a RAM or the like and executes the program. The program stored in the ROM is a program in which a processing method of the controller 50 is described.

<Configuration of controller 50>
In the 120-degree energization control using the Hall sensor, the energization pattern of the U-phase coil, V-phase coil, and W-phase coil of the motor is switched every 60 degrees (electrical angle) based on the output signal of the Hall sensor. A rectangular wave voltage according to the energization pattern is applied to each phase coil of the motor. However, the rectangular wave contains many harmonic components and causes noise and vibration of the motor.

  Vector control is known as an inverter control method that replaces rectangular wave driving such as 120-degree conduction control. In the vector control, a sine-wave voltage is generated using a rotational position sensor having a high resolution, such as an optical encoder or a resolver. As a result, smooth motor driving with low noise and low vibration is realized. However, sensors with high resolution are generally expensive. In addition, vector control requires coordinate transformation and complicated arithmetic processing, and requires a large amount of arithmetic. Therefore, it is necessary to use a microcomputer having a high arithmetic ability, which also increases costs.

  Therefore, in motor driving device 1 according to the present embodiment, an inverter control method capable of suppressing harmonic components at low cost without using a rotational position sensor having a high resolution or a microcomputer having a high computing capability is employed. Specifically, in the motor drive device 1, the controller 50 detects the electrical angle of the motor 40 every 60 degrees using the Hall sensors 62, 64, and 66, similarly to the conventional 120-degree conduction control. Further, the controller 50 generates an output pattern of the inverter 30 for each electrical angle of 60 degrees, and generates a rectangular wave voltage command based on the output pattern.

  In motor driving device 1 according to the present embodiment, controller 50 multiplies the generated rectangular wave voltage command by a correction coefficient prepared in advance to convert the rectangular wave voltage command into a sine wave voltage command. to correct. Then, the controller 50 generates gate signals G <b> 1 to G <b> 6 of the inverter 30 based on the voltage command corrected in the sine wave shape and outputs the gate signals G <b> 1 to G <b> 6 to the inverter 30.

  In this manner, in the motor driving device 1, a sine-wave voltage command is generated based on the rectangular wave control using the Hall sensors 62, 64, and 66 without using the vector control, and the motor 40 is driven. (Sine wave drive). Hereinafter, the configuration of the controller 50 that realizes these functions will be described in detail.

  FIG. 2 is a functional block diagram showing a configuration of a portion related to speed control of the controller 50 shown in FIG. Referring to FIG. 2, controller 50 includes a signal switching detection unit 110, an output pattern generation unit 112, a speed detection unit 114, a subtraction unit 116, and a speed control unit 118. The controller 50 further includes a voltage command generation unit 120, a sine wave correction unit 122, and a gate signal generation unit 124.

  The signal switching detection unit 110 receives output signals Hu, Hv, and Hw of the Hall sensors 62, 64, and 66, and detects switching of the H / L level of each signal. By detecting each switching of the signals Hu, Hv, Hw, the rotor position of the motor 40 can be detected.

  FIG. 3 is a waveform diagram of the output signals Hu, Hv, Hw of the Hall sensors 62, 64, 66. Referring to FIG. 3, signal Hu switches from the H level to the L level at time t1 and switches from the L level to the H level at time t4 according to the rotation of the rotor of motor 40. Thereafter, signal Hu switches from H level to L level again at time t7.

  Similarly to the signal Hu, the signal levels of the signals Hv and Hw are switched according to the rotation of the rotor of the motor 40. Since the three Hall sensors 62, 64, and 66 are arranged every 120 degrees in electrical angle, the switching timing of any one of the signals Hu, Hv, and Hw is every 60 degrees in electrical angle. Thus, by combining the signals Hu, Hv, Hw of the Hall sensors 62, 64, 66, the electrical angle of the motor 40 is detected every 60 degrees.

  Referring to FIG. 2 again, output pattern generation section 112 receives switching timing of signals Hu, Hv, Hw of Hall sensors 62, 64, 66 from signal switching detection section 110, and outputs an inverter corresponding to the switching timing. Generate 30 output patterns. Specifically, the output pattern generation unit 112 repeatedly generates six patterns PT1 to PT6 that are switched according to the switching timing of the signals Hu, Hv, and Hw (FIG. 3). Specifically, for example, the times t1 to t2, t2 to t3, t3 to t4, t4 to t5, t5 to t6, and t6 to t7 in FIG. At times t7 to t8 and t8 to t9, the patterns become the patterns PT1 and PT2, respectively. As will be described later, the voltage command generation section 120 generates a rectangular wave voltage command according to this output pattern.

  The speed detection unit 114 receives the switching timing of the signals Hu, Hv, and Hw of the Hall sensors 62, 64, and 66 from the signal switching detection unit 110, and detects the rotation speed of the motor 40 using the switching timing. That is, since the interval between the adjacent switching timings of the signals Hu, Hv, Hw is a time every 60 degrees in electrical angle, by measuring the interval between the switching timings of the signals Hu, Hv, Hw, the motor 40 can be measured. Can be detected. As an example, when the motor 40 is a two-pole motor, the speed detection unit 114 measures the interval between six consecutive switching timings (for one rotation of the rotor), and divides 2π by the measured time (seconds). The rotation speed (rad / sec) is calculated.

  The subtraction unit 116 calculates a speed deviation by subtracting the speed detection value received from the speed detection unit 114 from the speed command value of the motor 40 received from a higher-level control unit (not shown), and calculates the speed deviation by using the speed control unit. Output to 118.

  Speed controller 118 performs, for example, a proportional-integral operation with the speed deviation received from subtractor 116 as an input, and outputs the operation result to voltage command generator 120. That is, the speed control unit 118 executes the speed feedback (FB) control based on the deviation between the speed command value and the detected speed value.

  The voltage command generator 120 generates a rectangular wave voltage command (hereinafter, referred to as a “rectangular wave voltage command”) based on the output pattern generated by the output pattern generator 112 and the output of the speed controller 118. I do. Specifically, the voltage command generation unit 120 generates a rectangular wave voltage command in which the energization of each phase coil is switched every 180 electrical degrees and the energization patterns between the phases are shifted from each other by 120 degrees. This rectangular wave voltage command is equivalent to the rectangular wave voltage command generated in the conventional 180-degree energization control. The magnitude of the rectangular wave voltage command is adjusted according to the output of the speed control unit 118.

  As an actual calculation, the voltage command generation unit 120 sequentially receives the patterns PT1 to PT6 from the output pattern generation unit 112 according to the rotation of the motor 40. Further, voltage command generation section 120 receives the calculation result from speed control section 118. Then, the voltage command generation unit 120 generates the above-described rectangular wave voltage command in which the energization pattern is switched for each of the patterns PT1 to PT6. The generated waveform of the rectangular wave voltage command will be described later with reference to FIG.

  The sine wave correction unit 122 corrects the rectangular wave voltage command generated by the voltage command generation unit 120 into a sine wave voltage command using a correction coefficient for correcting a rectangular wave to a sine wave. Specifically, a correction coefficient for correcting the rectangular wave of each phase of U, V, and W into a sine wave is prepared in advance as a map for each of the patterns PT1 to PT6 and stored in the ROM. Then, the sine wave correction unit 122 obtains a correction coefficient from the correction coefficient map according to the patterns PT1 to PT6, and multiplies the rectangular wave voltage command generated by the voltage command generation unit 120 by the correction coefficient to obtain U, The rectangular wave voltage command of each phase of V and W is corrected to a sinusoidal voltage command.

  FIG. 4 is a waveform diagram illustrating a rectangular wave voltage command generated by the voltage command generation unit 120 and a sine wave voltage command corrected by the sine wave correction unit 122. In FIG. 4, U + indicates a voltage applied to the U-phase coil in the positive direction when the U-phase upper arm is turned on, and U− indicates a voltage applied to the U-phase coil in the negative direction when the U-phase lower arm is turned on. Indicates the applied voltage. V +, W +, V- and W- are the same as U + and U-. A dotted line indicates a rectangular wave voltage command generated by the voltage command generation unit 120, and a solid line indicates a sine wave voltage command corrected by the sine wave correction unit 122.

  Referring to FIG. 4, voltage command generating section 120 outputs a positive-direction rectangular wave voltage to U-phase coil in patterns PT1 to PT3, and outputs a negative-direction rectangular wave voltage to U-phase coil in patterns PT4 to PT6. To generate a U-phase rectangular wave voltage command. Further, voltage command generating section 120 outputs a positive-direction rectangular wave voltage to the V-phase coil in patterns PT3 to PT5, and outputs a negative-direction rectangular wave voltage to the V-phase coil in patterns PT1, PT2, and PT6. Then, a V-phase rectangular wave voltage command is generated. Further, voltage command generating section 120 outputs a rectangular wave voltage in the positive direction to the W-phase coil in patterns PT1, PT5, and PT6, and outputs a rectangular wave voltage in the negative direction to the W-phase coil in patterns PT2 to PT4. Then, a W-phase rectangular wave voltage command is generated. Note that the magnitude of each phase rectangular wave voltage command is adjusted according to the output of the speed control unit 118 (FIG. 2).

  The sine wave correction unit 122 multiplies the rectangular wave voltage command generated by the voltage command generation unit 120 by a correction coefficient for correcting the square wave to a sine wave, as shown in FIG. Is corrected to a sinusoidal voltage command.

  FIG. 5 is a diagram illustrating an example of a map of correction coefficients used in the sine wave correction unit 122. With reference to FIG. 5 and FIG. 4, in the pattern PT <b> 1, in response to the U-phase rectangular wave voltage command, a correction coefficient that continuously changes from sin0 to sin (π / 3) in this section is set to the U-phase rectangular wave voltage command. (See U + in FIG. 4). The V-phase rectangular wave voltage command is multiplied by a correction coefficient that continuously changes from sin (4π / 3) to sin (5π / 3) in this section (FIG. 4). V-), the W-phase rectangular wave voltage command is multiplied by a correction coefficient that continuously changes from sin (2π / 3) to sinπ in this section (FIG. 4). W +).

  Here, as the time required for the change, the time of the previous pattern is used. Specifically, referring to FIG. 4, for example, in pattern PT1 at times t11 to t12, the correction coefficient in pattern PT1 is obtained using time Δt0 from time t10 to time t11 in the preceding section. Although the time of the pattern PT1 is actually the time Δt1, when calculating the correction coefficient in the pattern PT1, the correction coefficient is obtained using the time Δt0 of the previous section. Assuming that the speed change from the preceding section is small, Δt1 ≒ Δt0, the correction coefficient in the pattern PT1 can be obtained at the start of the pattern PT1 (time t11). For this reason, in this embodiment, the switching time of the signals Hu, Hv, Hw of the Hall sensors 62, 64, 66 is calculated, and is used for calculating the correction coefficient in the pattern immediately after that.

  Similarly, for example, in pattern PT2 from time t12 to t13, a correction coefficient in pattern PT2 is obtained using time Δt1 (time t11 to t12) of pattern PT1 in the previous section, and the rectangular wave voltage command is corrected. You. As described above, the rectangular wave voltage command generated by the voltage command generator 120 is sine based on the map shown in FIG. 5 and the switching time of the signals Hu, Hv, Hw of the Hall sensors 62, 64, 66. It can be corrected to a wavy voltage command (FIG. 4).

  Referring to FIG. 2 again, gate signal generating section 124 drives switching elements Sw1 to Sw6 of inverter 30 based on the U, V, and W phase voltage commands corrected in the sine wave form by sine wave correcting section 122. To generate gate signals G1 to G6. Although not described in detail, the gate signal generation unit 124 uses, for example, a well-known PWM method to generate the gate signals G1 to G6 for driving the switching elements Sw1 to Sw6 from the U, V, and W phase voltage commands. Can be generated.

  For reference, FIG. 6 is a waveform diagram of a voltage command in the conventional 120-degree conduction control. Referring to FIG. 6, in the 120-degree conduction control, a rectangular wave voltage in the positive direction is output to the U-phase coil in patterns PT1 to PT2, and a rectangular wave voltage in the negative direction is output to the U-phase coil in patterns PT4 to PT5. Thus, the U-phase rectangular wave voltage command is generated. Also, the V-phase rectangular wave voltage command is output such that a positive-direction rectangular wave voltage is output to the V-phase coil in the patterns PT3 to PT4, and a negative-direction rectangular wave voltage is output to the V-phase coil in the patterns PT1 and PT6. Generated. Further, the W-phase rectangular wave voltage command is output such that a positive-direction rectangular wave voltage is output to the W-phase coil in the patterns PT5 and PT6, and a negative-direction rectangular wave voltage is output to the W-phase coil in the patterns PT2 and PT3. Generated. Then, switching elements Sw1 to Sw6 of inverter 30 are turned on / off in accordance with the energization pattern shown in FIG.

  FIG. 7 is a flowchart illustrating an example of a processing procedure executed by the controller 50. Referring to FIG. 7, controller 50 obtains signals Hu, Hv, Hw of Hall sensors 62, 64, 66 (step S10). Then, the controller 50 detects switching of the H / L level for each of the acquired signals Hu, Hv, and Hw (Step S15). By detecting each switching of the signals Hu, Hv, Hw, the electric angle of the motor 40 is detected every 60 degrees.

  Then, the controller 50 generates an output pattern (patterns PT1 to PT6) according to the switching of the signals Hu, Hv, Hw (Step S20). Further, the controller 50 calculates the switching time of the signals Hu, Hv, Hw (Step S30). This switching time is used when detecting the rotation speed of the motor 40 in the next step S40, and in step S70 described later, the rectangular wave voltage command is converted into a sine wave using the correction coefficient map shown in FIG. It is also used when correcting to the voltage command of.

  Next, the controller 50 detects the rotation speed of the rotor of the motor 40 (Step S40). Since the electrical angle is known from the switching of the signals Hu, Hv, Hw, the rotation speed of the rotor can be calculated from the switching time of the signals Hu, Hv, Hw.

  Then, the controller 50 executes speed control for adjusting the rotation speed of the motor 40 to the speed command value (Step S50). Specifically, the controller 50 executes speed feedback control based on a deviation between the speed command value and the speed detection value, and generates an operation amount for adjusting the magnitude of the rectangular wave voltage command.

  Next, the controller 50 generates a rectangular wave voltage command (dotted line in FIG. 4) based on the output pattern generated in Step S20 (Step S60). In addition, the controller 50 adjusts the magnitude of the rectangular wave voltage command in a direction in which the speed deviation decreases in accordance with the operation amount of the speed control executed in step S50.

  Further, the controller 50 corrects the generated rectangular wave voltage command into a sinusoidal voltage command using the correction coefficient map shown in FIG. 5 (Step S70). Here, as the time required for changing the correction coefficient in a certain pattern (for example, pattern PT2), the time of the pattern (pattern PT1) before that pattern is used. Thereby, at the timing when the pattern shifts according to the switching of the signals Hu, Hv, Hw of the Hall sensors 62, 64, 66, the change of the correction coefficient in the pattern after the shift can be obtained.

  Then, the controller 50 generates gate signals G1 to G6 for driving the switching elements Sw1 to Sw6 of the inverter 30 based on the sine-wave corrected voltage command, and generates the gate signals G1 to G6. Output to the inverter 30 (step S80). The gate signals G1 to G6 can be generated from a voltage command using a known PWM method.

  FIG. 8 is a diagram illustrating an example of a comparison result between the processing time when the control method according to the present embodiment is applied and the processing time when vector control is applied as a comparative example. Note that the former processing time is the time from when the output signals of the Hall sensors 62, 64, and 66 are obtained (Step S10 in FIG. 7) to when the voltage command is corrected (Step S70 in FIG. 7). Is the time from the acquisition of the electric angle of the motor to the coordinate conversion, current control, coordinate reverse conversion, and PWM processing. In each case, the processing time is measured using the same controller having the same processing speed, and there is no difference in processing time due to a difference in hardware performance.

  Referring to FIG. 8, the processing time when using the vector control was 47.20 μsec, whereas the processing time when using the control method according to the present embodiment was 16.84 μsec. . For this reason, the present method uses a sinusoidal waveform without the use of a microcomputer having a high computing capability as in the case of using vector control, and without using a high-resolution rotational position sensor such as an optical encoder or a resolver. By generating a voltage command, it is possible to realize motor control in which harmonics are suppressed.

  As described above, in this embodiment, the rectangular wave voltage command generated based on the output pattern for every 60 electrical degrees is corrected to a sinusoidal voltage command using a correction coefficient prepared in advance. . Since the inverter 30 is controlled based on the sinusoidal voltage command, harmonic components such as the conventional 120-degree rectangular wave control are suppressed, and noise and vibration of the motor 40 are suppressed. In addition, a sine-wave voltage command can be generated by a simple method using a correction coefficient without using a sensor having a high resolution, a microcomputer having a high calculation capability, or the like as in the vector control method. Therefore, according to this embodiment, it is possible to realize a motor drive device capable of suppressing harmonic components at low cost.

[Modification]
In the above embodiment, the rectangular wave voltage command is corrected to the sine wave voltage command using the correction coefficient. However, the voltage command may be corrected to the triangular wave voltage command instead of the sine wave. Even with such a voltage command, harmonics can be suppressed as compared with the case of the rectangular wave drive. Further, since the triangular wave has a simpler waveform than the sine wave, it is possible to further reduce the amount of arithmetic processing, memory occupancy, and the like when correcting the voltage command.

  In this modification, although not particularly shown, a triangular wave correction unit is provided instead of the sine wave correction unit 122 shown in FIG. The triangular wave correction unit corrects the rectangular wave voltage command generated by the voltage command generation unit 120 (FIG. 2) into a triangular wave voltage command using a correction coefficient for correcting a rectangular wave to a triangular wave. Specifically, a correction coefficient for correcting the rectangular wave of each phase of U, V, and W into a triangular wave is prepared in advance as a map for each of the patterns PT1 to PT6 and stored in the ROM. Then, the triangular wave correction unit obtains a correction coefficient from the correction coefficient map according to the patterns PT1 to PT6, and multiplies the rectangular wave voltage command generated by the voltage command generation unit 120 by the correction coefficient, thereby obtaining U, V, The rectangular wave voltage command of each phase of W is corrected to a triangular wave voltage command.

  FIG. 9 is a waveform diagram illustrating a rectangular wave voltage command generated by the voltage command generation unit 120 and a triangular wave voltage command corrected by the triangular wave correction unit in this modification. In FIG. 9, as in FIG. 4, the dotted line indicates a rectangular wave voltage command generated by the voltage command generator 120, and the solid line indicates a triangular wave voltage command corrected by the triangular wave corrector.

  Referring to FIG. 9, the triangular wave correction unit multiplies the rectangular wave voltage command generated by voltage command generation unit 120 by a correction coefficient for correcting a rectangular wave to a triangular wave, as shown in FIG. The wavy voltage command is corrected to a triangular wave voltage command.

  FIG. 10 is a diagram illustrating an example of a map of correction coefficients used in the triangular wave correction unit. Referring to FIG. 9 together with FIG. 10, in pattern PT1, a correction coefficient that continuously changes from 0 to 0.67 (2/3) in this section with respect to the U-phase rectangular wave voltage command The voltage command is multiplied (see U + in FIG. 9). In addition, for the V-phase rectangular wave voltage command, a correction coefficient that continuously changes from −0.67 (− ／) to −1 to −0.67 (− ／) in this section is V. The phase-coefficient rectangular wave voltage command is multiplied (see V- in FIG. 9), and for the W-phase rectangular wave voltage command, a correction coefficient that continuously changes from 0.67 (2/3) to 0 in this section. The W-phase rectangular wave voltage command is multiplied (see W + in FIG. 9).

  As for the time required for the change, the time of the previous pattern is used as in the above embodiment. As described above, the rectangular wave voltage command generated by the voltage command generation unit 120 is triangulated based on the map shown in FIG. 10 and the switching time of the signals Hu, Hv, Hw of the Hall sensors 62, 64, 66. It can be corrected to a wavy voltage command (FIG. 9).

  As described above, according to this modified example, the same effect as in the above embodiment can be obtained. Further, since the generation of the triangular wave is simpler than the generation of the sine wave, the memory occupancy of the controller 50 and the like can be further reduced as compared with the above embodiment in which the sine wave is corrected.

  In the above-described embodiment and modifications, the rotor position of the motor 40 is detected at every 60 degrees (electrical angle) using the Hall sensors 62, 64, and 66. The rotor position of the motor 40 may be estimated without using the sensor 66 (sensorless). For example, the rotor position may be estimated by detecting an induced voltage generated in each phase coil of the motor 40 as in known sensorless energization control.

  Further, in the above embodiment and the modified example, the speed control based on the deviation between the speed command value and the speed detection value is performed. However, the current on the DC side (input side) of the inverter 30 is detected and the current command is detected. Current control based on the deviation from the value may be performed. In this case, for example, a proportional-integral operation may be performed by using a deviation between the current instruction value and the current detection value as an input, and the operation result may be output to the voltage instruction generation unit 120.

  The embodiments disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description of the embodiments, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  Reference Signs List 1 motor drive device, 10 DC power supply, 20 capacitor, 30 inverter, 40 motor, 50 controller, 62, 64, 66 Hall sensor, 110 signal switching detection unit, 112 output pattern generation unit, 114 speed detection unit, 116 subtraction unit, 118 speed control unit, 120 voltage command generation unit, 122 sine wave correction unit, 124 gate signal generation unit.

Claims (4)

A motor driving device for driving a motor,
Position detection means for detecting the rotor position of the motor for each predetermined rotation angle,
An inverter that drives the motor;
A control device for controlling the inverter according to a detection signal of the position detection means,
The control device includes:
Generating an output pattern of the inverter for each of the predetermined rotation angles according to the detection signal;
The output command of the rectangular wave inverter generated based on the output pattern is corrected to a sine wave or triangular wave output command using a correction coefficient prepared in advance,
A motor drive device that controls the inverter based on the corrected output command. The correction coefficient is prepared for each of the output patterns,
The control device includes:
Acquiring the switching time of the output of the position detecting means that switches at every predetermined rotation angle,
Based on the switching time acquired in a first pattern of the output patterns and the correction coefficient in a second pattern following the first pattern, the output command in the second pattern is The motor drive device according to claim 1, wherein the correction is performed. The control device includes:
Generate a rectangular wave voltage command of the inverter based on the output pattern and the rotation speed of the motor,
The motor drive device according to claim 1, wherein a sine-wave or triangular-wave voltage command for the inverter is generated by multiplying the rectangular wave voltage command by the correction coefficient for each of the output patterns.   4. The motor drive device according to claim 1, wherein the position detection unit includes a plurality of Hall sensors. 5.

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