JP2010288340A - Motor controller and motor control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor controller and a motor control method which enable low-cost and stable rotation control even when it rotates at low speed. <P>SOLUTION: This motor controller, which controls the rotational frequency of a motor, includes a rotational frequency detection part which detects the rotational frequency of the motor as a cyclic output voltage, a reference potential holding part which holds two or more reference potentials based on the value of the output voltage, a rotational frequency measuring part which measures the cycles of each reference potential where the output voltage takes the same potential as each of the two or more reference potentials in the successive cyclic period of the output voltage as the rotational frequency of the motor, a rotational frequency comparator which compares the rotational frequency of the motor detected by the rotational frequency measuring part with the target rotational frequency of the motor, an acceleration command generating part which generates acceleration based on the comparison result of the rotational frequency comparator, and a driver which controls the rotational frequency of the motor by driving the motor according to the acceleration generated by the acceleration command generating part. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a motor control device and a motor control method, and more particularly to a motor control device and a motor control method for controlling the rotational speed of a motor.

  There is known a motor control device that controls the motor rotation speed by detecting the rotation speed of the motor and feeding back the difference from the target rotation speed (see, for example, Patent Document 1). Hereinafter, a conventional motor control device disclosed in Patent Document 1 will be described.

FIG. 11 is a diagram illustrating an example of a configuration of a conventional motor control device. A motor control device 1000 shown in FIG. 11 includes a rotation number information generation unit 1001, a detected rotation number counter 1002, a target rotation number counter 1010, a rotation number comparator 1020, an acceleration command generation unit 1030, a driver 1040, a motor 1050, and a motor 1050. An FG (Frequency Generator) 1060 for detecting the number of rotations is provided. In this motor control apparatus 1000, the number of revolutions of the motor 1050 is detected by the FG 1060, the timing at which the revolution number information generation unit 1001 becomes the reference potential (for example, VFG2) is detected, and the detected number of revolutions counter 1002 counts the motor. A period indicating a rotation speed of 1050 is measured. Then, the measured cycle and the target rotational speed (N _EXC ) are compared by the rotational speed comparator 1020, and the error is fed back to the acceleration command generation unit 1030, and the rotational speed of the motor is controlled by the driver 1040.

  Here, a general method for detecting the rotational speed of the motor at the low cost in the motor control apparatus 1000 will be described. The motor 1050 will be described below as including a brushless motor in which a rotor called a rotor, for example, is magnetized, and a drive coil is composed of a stator and a rotor called a stator.

  FIG. 12 is a diagram showing an example of a rotor and a motor substrate magnetized in a 6-pole pair in a conventional motor control device. FIG. 12A shows an example in which the motor of the conventional motor control device is a brushless motor, and the rotor 1100 is magnetized to 6 pole pairs. FIG. 12B shows an example in which an FG (Frequency Generator) pattern 1102 is depicted on the motor substrate 1101 or a Hall element 1202 for position detection is mounted.

  In the conventional motor control device, the output signal of the position detecting Hall element 1202 mounted on the motor board 1101 can be used as a rotation speed signal. Alternatively, by using the FG pattern 1102 drawn by metal wiring on the motor substrate 1101, the magnetic flux change of the rotor 1100 can be changed to a voltage (VFG1-VFG2 in the figure) and extracted as a rotation speed signal.

  Thus, the motor control apparatus 1000 can detect the rotation speed of the motor by using the Hall element 1202 or the FG pattern 1102 that can be provided at low cost.

  Next, a difference in the case where the Hall element 1202 and the FG pattern 1102 are used for the FG 1060 when the rotation speed information generation unit 1001 detects the rotation speed of the motor 1050 will be described.

  FIG. 13 is a diagram for explaining the starting operation of the motor when the FG pattern is used. On the other hand, FIG. 14 is a diagram for explaining the starting operation of the motor in the case of using the Hall element. FIG. 15 is a diagram comparing the amplitude of the output voltage with the number of revolutions when using a Hall element and an FG pattern for FG.

When the FG pattern 1102 is used, the FG pattern 1102 generates an output voltage due to a change in the magnetic flux of the rotor 1100. Therefore, as shown in FIG. 13, the FG 1060 has an output voltage having an amplitude proportional to the rotational speed of the motor 1050 (hereinafter, FG output voltage). Therefore, when the rotation of the motor 1050 is rotating at a low speed, the amplitude of the FG output voltage output by the FG 1060 is small, and the rotation speed information generation unit 1001 may not be able to recognize. That is, as shown in FIG. 13B, the rotation speed information generation unit 1001 cannot read a low speed rotation speed of N _NUC or less corresponding to V _ID if the FG output voltage cannot be recognized with an amplitude of V _ID or less. (It cannot be detected), so the rotational speed of the motor 1050 cannot be controlled at a low rotational speed of N _NUC or less.

  On the other hand, when the Hall element 1202 is used, the Hall element 1202 outputs in accordance with the magnitude of the magnetic field of the magnetized rotor 1100. Therefore, as shown in FIG. 14, the FG 1060 does not depend on the motor rotation speed. Outputs a constant amplitude output voltage (hereinafter referred to as Hall output voltage). Therefore, since the amplitude of the Hall output voltage output by the FG 1060 is constant even if the rotation of the motor 1050 is a low-speed rotation, the rotation speed information generation unit 1001 can recognize, that is, detect the rotation speed of the motor 1050. The number of rotations of the motor 1050 can be controlled.

  Therefore, as shown in FIG. 15, the FG output voltage output by FG 1060 using FG pattern 1102 (described as FG output in the figure) is the Hall output voltage output by FG 1060 using Hall element 1202 in the low-speed rotation region. Unlike (shown as hall output in the figure), the amplitude is small, so it is difficult to control the rotation speed of the motor 1050. Therefore, in order to control the rotation speed of the motor 1050 even in the low-speed rotation region, the motor control apparatus 1000 preferably detects the rotation speed of the motor 1050 using the Hall element 1202.

JP 2005-278279 A

  However, there are the following problems in detecting the rotational speed of the motor using the Hall element 1202.

  Since the frequency of the signal (output voltage) output from the FG 1060 (hereinafter referred to as the output frequency) is a resolution for correcting the rotational speed when the rotational speed of the motor 1050 is controlled, a higher frequency of the signal is preferred. It is. When the FG pattern 1102 is used, a signal having an output frequency proportional to the number of pattern steps (for example, 44 pulses per rotation) can be extracted. However, when the Hall element 1202 is used, for example, when the rotor 1100 is a 6-pole pair, only 6 pulse signals can be extracted per rotation, and in reality, the rotor magnetization number is set to be larger than the number of FG pattern steps. It is difficult. Here, FIG. 16 and FIG. 17 show the relationship between the output voltage, the frequency, and the amplitude when the rotation speed of the motor 1050 is the same. FIG. 16 is a diagram showing a comparative example of the output frequency when the rotation speed is detected using the Hall element and the FG pattern, and FIG. 17 is a rotation speed detection using the Hall element and the FG pattern. It is the figure which compared the amplitude example of the output voltage at the time of a case on a time axis.

  As described above, the higher the output frequency, the higher the resolution. Therefore, it is preferable to use the FG pattern. However, since the rotor 1100 and the motor substrate 1101 are small in size, there is a limit to the number of FG pattern increments, and since the FG pattern has a low amplitude during low-speed rotation as described above, the rotation speed of the motor 1050 in the low-speed rotation region. Although it is repeated, it is realistic to use the Hall element.

  Hereinafter, the problem in the case where the motor control apparatus 1000 detects the rotation speed of the motor 1050 using the Hall element 1202 will be described in detail.

  FIG. 18 is a diagram showing the operation timing of the detected rotation speed counter in the conventional motor control device. FIG. 19 is a diagram illustrating a state in which an acceleration / deceleration command is output in a conventional motor control device.

  The rotation speed information generation unit 1001 detects the timing when the output signal (FIG. 18A) indicating the output voltage output from the FG 1060 becomes a predetermined reference potential (for example, VFG2), and at the detected timing. A pulse indicating the rotation speed information is output (FIG. 18B). The rotation speed information generation unit 1001 outputs a pulse at the timing when the output signal becomes the reference potential again as shown in FIG. The detected rotation number counter 1002 counts the period between pulses output from the rotation number information generation unit 1001. Similarly, the period between pulses is sequentially counted. Here, one cycle means the time for one pole pair of the six pole pairs of the rotor 1100 to pass through the Hall element 1202.

Next, the rotation speed comparator 1020 compares a count value (rotation speed signal), which is a cycle between pulses counted at arbitrary times t−1, t, and t + 1, with the target rotation speed N _EXC . As shown in FIGS. 19A and 19B, the rotation speed comparator 1020 _satisfies N _EXC > N _FB (t−1) at an arbitrary time t−1. Therefore, if the rotation of the motor 1050 is too fast, It recognizes and outputs a deceleration command (DE) for the error time (FIG. 19C). Similarly, the rotational speed comparator 1020 conversely recognizes that the rotation of the motor 1050 is too slow because N _EXC <N _FB (t) and NEXC <NFB (t + 1) at arbitrary times t and t + 1, and the acceleration command ( AC) is output for the error time (FIG. 19C).

  Thus, when the motor control device 1000 detects the number of rotations of the motor 1050 using the Hall element 1202, it can only output an error signal once per cycle. Only about 6 pulses can be extracted per rotation. That is, since the number of rotation speed corrections is small (resolution is low), stable control is difficult in a low-speed rotation region where one cycle is relatively long. In this respect, for example, a high resolution sensor such as a rotary encoder can be used to solve the problem technically. However, since the cost increases, the range of use is limited.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a motor control device and a motor control method that enable stable rotation speed control at low cost even when rotating at a low speed. .

  In order to solve the above problems, a motor control device according to the present invention is a motor control device that controls the rotation speed of a motor, and a rotation speed detection unit that detects an output voltage having a period according to the rotation speed of the motor. A reference potential holding unit that holds two or more reference potentials based on the value of the output voltage, and each of the output voltages having the same potential as each of the two or more reference potentials during a continuous period of the output voltage. A rotation speed measurement unit that measures a reference potential cycle as information related to the rotation speed of the motor; information related to the rotation speed of the motor detected by the rotation speed measurement section; and information related to a rotation speed that is a target of the motor; A rotation speed comparator, an acceleration command generation section that generates an acceleration instruction based on a comparison result of the rotation speed comparator, and the acceleration finger generated by the acceleration command generation section And a driver for controlling the rotation speed of the motor by driving the motor in accordance with.

  With this configuration, for example, the rotational speed correction can be performed two or more times even during one cycle of the output voltage by the Hall element. As a result, it is possible to realize a motor control device that enables stable rotation speed control at low cost even when the motor rotates at a low speed.

  The reference potential holding unit is obtained from a sample-and-hold unit that samples and holds the peak and valley voltage values in the output voltage detected by the rotation number detection unit, and the sample-held voltage value. A divided reference potential generation unit that divides a peak-to-peak value by a predetermined number of two or more and generates and holds the two or more reference potentials using the divided peak-to-peak value may be provided.

  With this configuration, if the rotation speed of the motor can be detected with a periodic output voltage, for example, if there is variation in the magnetic flux of the motor and the waveform of the output voltage is not like a sine wave, there is periodicity. Even during one cycle of the output voltage, the number of rotations can be corrected two or more times.

  In order to solve the above problems, a motor control method according to the present invention is a motor control method for controlling the rotational speed of a motor, and detects the output voltage having a period corresponding to the rotational speed of the motor. A detection step; a reference potential holding step for holding two or more reference potentials based on the value of the output voltage; and the output voltage becomes the same as each of the two or more reference potentials during a continuous period of the output voltage. Revolution measurement step for measuring each reference potential cycle as information on the rotation speed of the motor, information on the rotation speed of the motor detected in the rotation speed measurement step, and a rotation speed that is a target of the motor Rotation speed comparison step for comparing information and acceleration command generation for generating an acceleration instruction based on the comparison result in the rotation speed comparison step And step, by driving the motor in accordance with the acceleration instruction generated in the acceleration command generation step and a control step of controlling the rotational speed of the motor.

  According to the present invention, it is possible to realize a motor control device and a motor control method that enable stable rotation speed control at low cost even when rotating at a low speed.

It is a block diagram which shows the structure of the motor control apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows a mode that an output voltage amplitude is sample-held. It is the figure which showed a mode that output voltage was divided into n by each reference potential. It is a figure which shows a mode that a rotation speed information generation part outputs a timing signal (pulse) to a detection rotation speed counter. It is a figure for demonstrating the relationship between operation | movement of a detection rotation speed counter, and operation | movement of a rotation speed comparator. It is a figure for demonstrating the case where the waveform of an output voltage is distorted. It is a figure for demonstrating the case where the waveform of the output voltage which concerns on the modification of Embodiment 1 of this invention has dispersion | variation. It is a figure which shows the general view of the washing machine provided with the motor control apparatus which concerns on this invention. It is a figure which shows the general view of the printer provided with the motor control apparatus which concerns on this invention. It is a figure which shows the general view of the electric vehicle provided with the motor control apparatus which concerns on this invention. It is a figure which shows one example of a structure of the conventional motor control apparatus. It is a figure which shows the example of the rotor magnetized by the 6 pole pair in the conventional motor control apparatus, and the example of a motor board | substrate. It is a figure for demonstrating the starting operation | movement of a motor in the case of using an FG pattern. It is a figure for demonstrating the starting operation | movement of a motor in the case of using a Hall element. It is the figure which compared the amplitude of the output voltage in the case of using a Hall element and FG pattern for FG with the rotation speed. It is a figure which shows the comparative example of the output frequency at the time of performing rotation speed detection using a Hall element and FG pattern. It is the figure which compared the amplitude example of the output voltage at the time axis | shaft at the time of performing rotation speed detection using a Hall element and FG pattern. It is a figure which shows the operation timing of the detection rotation speed counter in the conventional motor control apparatus. It is the figure which showed a mode that the acceleration / deceleration command was output in the conventional motor control apparatus.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of a motor control device according to Embodiment 1 of the present invention.

  As shown in FIG. 1, the motor control device 200 includes a target rotation speed holding unit 10, a rotation speed comparator 20, an acceleration command generation unit 30, a motor driving driver 40, and a rotation speed detection unit (denoted as FG in the figure). 60), a sample and hold unit 70, a 1 / n division reference potential generation unit 80, a rotation number information generation unit 90, and m detection rotation number counters 100. The motor control device 200 controls the motor 50 so as to reach the target rotational speed.

The target rotational speed holding unit 10 receives a target rotational speed signal indicating the target rotational speed from the outside. Here, the target rotational speed signal indicating the target rotational speed is a signal having a waveform having periodicity, and the cycle varies according to the target rotational speed. The target rotational speed holding unit 10 always counts a period (hereinafter referred to as a target period) obtained from the input target rotational speed signal, and the counted target rotational speed count value N _EXC is counted as the rotational speed comparator 20. Output to.

For example, the rotational speed comparator 20 counts the detected rotational speed count values N _FB 1 (t) to N _FB m (t) counted by the detected rotational speed counter 100 at the time t and the target rotational speed holding unit 10. Is inputted with the target rotational speed count value N _EXC . The rotational speed comparator 20 compares the input target rotational speed count value N _EXC with the detected rotational speed count values N _FB 1 (t) to N _FB m (t), and these target rotational speed count values N _EXC. And the detected rotation speed count value N _FB 1 (t) to N _FB m (t) are detected as errors. The rotation speed comparator 20 determines the acceleration command AC if the target rotation speed count value N _EXC is smaller than an arbitrary detected rotation speed count value N _FB n (t): n = 1 to m, that is, if the motor 50 is slower than the target rotation speed. Is output to the acceleration command generator 30. The rotational speed comparator 20 determines that the target rotational speed count value N _EXC is an arbitrary detected rotational speed count value N _FB n (t): n = 1 to larger than 1 to m, that is, if the motor 50 is faster than the target rotational speed, the deceleration command DE is issued. Output to the acceleration command generator 30.

  The acceleration command generator 30 determines the acceleration of the motor 50 from the acceleration command AC and the deceleration command DE output from the rotation speed comparator 20, and outputs voltage waveform information applied to the motor 50 to the driver 40.

  The driver 40 converts the applied voltage waveform information input from the acceleration command generation unit 30 into a PWM (Pulse Width Modulation) signal, and applies a pulse voltage to the motor 50 according to the PWM signal.

  The FG 60 detects a signal indicating the rotation speed of the motor 50 as an output voltage having a period corresponding to the rotation speed of the motor 50, and outputs the detected output voltage to the sample and hold unit 70 and the rotation speed information generation unit 90. The FG 60 will be described below as detecting an output voltage having a period corresponding to the number of rotations of the motor 50 using a Hall element, but is not limited thereto. For example, the rotational speed of the motor 50 may be detected using a sensor such as a magnetic field detection. That is, the output element is not limited to the Hall element as long as it is a low-cost sensor that detects an output voltage that does not depend on the output amplitude detected by the rotational speed and has a period corresponding to the rotational speed. The FG 60 includes a plurality of Hall elements, but for the sake of simplicity, the following description will focus on the behavior of one Hall element.

The sample and hold unit 70 takes in the values of the peaks and valleys of the output voltage indicated by the signal output from the FG 60, and holds the values taken in for a fixed time while constantly updating. Here, FIG. 2 shows how the sample-and-hold unit 70 captures and holds the peak-to-peak value (hereinafter referred to as amplitude) of the output voltage. FIG. 2 is a diagram showing how the output voltage amplitude is sampled and held. In FIG. 2, for example, the waveform of the output voltage output by the FG 60 immediately after the start of the motor 50 is shown. As information indicating the amplitude of the output voltage, V _P1 and V that are peak values of peaks and troughs of the output voltage waveform are shown. Capture and hold _P2 . In this way, the sample and hold unit 70 holds the amplitude of the output voltage indicated by the signal output from the FG 60.

  The 1 / n divided reference potential generation unit 80 corresponds to a reference potential holding unit according to the present invention. The 1 / n-divided reference potential generation unit 80 divides the amplitude of the output voltage held in the sample-and-hold unit 70 by n, which is a preset integer of 1 or more, and outputs an output voltage corresponding to the n-divided amplitude A value is generated as a reference potential. The 1 / n-divided reference potential generation unit 80 outputs the generated reference potential to the rotation speed information generation unit 90. In addition, the resolution of rotation speed detection increases, so that n is large. Here, FIG. 3 shows how the 1 / n-divided reference potential generation unit 80 generates the reference potential.

FIG. 3 is a diagram illustrating how the output voltage is divided into n by each reference potential. As shown in FIG. 3, the 1 / n-divided reference potential generation unit 80 divides the amplitude held in the sample-and-hold unit 70 into n divisions, that is, (V _P1 −V _P2 ) / n, and the n-divided amplitude (V _P1 Output voltage values corresponding to -V _P2 ) / n are generated as reference potentials. FIG. 3 shows a waveform of one cycle of the output voltage, and shows an example in which seven reference potentials are generated assuming that n = 8. The potential difference between the reference potential and the next reference potential is described as (V _P1 −V _P2 ) / n, that is, an equally divided potential difference, but it may not be equally divided.

  The rotation speed information generation unit 90 receives a signal (output voltage) indicating the rotation speed of the motor 50 from the FG 60 and a reference potential from the 1 / n divided reference potential generation unit 80. The rotation speed information generation unit 90 generates a timing signal for determining the timing counted by the detected rotation speed counter 100 from the input signal (output voltage) indicating the rotation speed of the motor 50 and the reference potential. Specifically, the rotation speed information generation unit 90 has the same potential (coincidence) with each reference potential, the potential of the output voltage having a period corresponding to the rotation speed of the motor 50, which is a signal indicating the rotation speed of the motor 50. At this timing, a timing signal (pulse) is output as a signal indicating rotation speed information.

The detected rotational speed counter 100 includes m detected rotational speed counters, that is, a detected rotational speed counter 1 to a detected rotational speed counter m, and a plurality of timing signals (pulses) as signals indicating rotational speed information from the rotational speed information generation unit 90. Is entered. The detected rotational speed counter 100 counts the detected rotational speed count values N _FB 1 (t) to N _FB m (t) in accordance with a plurality of input timing signals (pulses). Then, the detected rotational speed counter 100 sequentially outputs the counted detected rotational speed count values N _FB 1 (t) to N _FB m (t) to the rotational speed comparator 20.

Specifically, the timing signal (pulse) from the rotation speed information generation unit 90 is input to each of the detection rotation speed counter 1 to the detection rotation speed counter m included in the detection rotation speed counter 100, and is detected. In accordance with the timing signal (pulse) to which the rotational speed counter m is input, the detected rotational speed count values N _FB 1 (t) to N _FB m (t) are counted and output to the rotational speed comparator 20 as respective periodic signals. To do. That is, the detected rotational speed counter n (1 to m) counts the period (time) of the timing signal (pulse) input from the rotational speed information generation unit 90, thereby detecting the detected rotational speed count value N _FB n (t ): N = 1 to m are counted and output to the rotation speed comparator 20.

  As described above, the rotation speed information generation unit 90 and the detected rotation speed counter 100 corresponding to the rotation speed measurement unit of the present invention have two or more reference values during a continuous cycle of the output voltage that is a signal indicating the rotation speed of the motor 50. The period of the same potential as each potential is measured as information corresponding to the rotation speed of the motor 50.

The motor control device 200 is configured as described above.
Next, operations of the rotation speed information generation unit 90, the detected rotation speed counter 100, and the rotation speed comparator 20 will be described with reference to the drawings.

  FIG. 4 is a diagram illustrating a state in which the rotation speed information generation unit outputs a timing signal (pulse) to the detected rotation speed counter. FIG. 4A shows a state in which seven reference potentials are generated assuming that n = 8 as in FIG. FIG. 4B shows a state in which the rotational speed information generation unit 90 outputs m timing signals (pulses) to the detected rotational speed counter 100 with an output voltage of one cycle that is a signal indicating the rotational speed of the motor 50. ing.

  As shown in FIG. 4B, the rotational speed information generation unit 90 detects the rotational speed of the detected rotational speed counter 100 that includes the timing signal (pulse) at the timing when the reference potential and the potential of the output voltage become the same potential. Output to any one of the counter 1 to the detected rotational speed counter m to start counting. Specifically, the rotational speed information generation unit 90 outputs, for example, a first timing signal (pulse) at an arbitrary time t to the detected rotational speed counter 1, and causes the detected rotational speed counter 1 to start counting. Similarly, the timing signal (pulse) of the n (2-m) th occurrence at time t is output to the detected rotation number counter n (2-m), and the detected rotation number counter n (2-m) starts counting.

  Since the rotation speed information generation unit 90 becomes a signal indicating the rotation speed information at time t + 1 from the m + 1th timing signal (pulse), the rotation speed information generation unit 90 outputs the m + 1th timing signal (pulse). (Pulse) as a first timing signal (pulse) at time t + 1 is output to the detected rotational speed counter 1. Since the same is true below, the description is omitted.

  Therefore, the rotation speed information generation unit 90 outputs a signal indicating the rotation speed information at time t + 1 to each of the detected rotation speed counter 1 to the detected rotation speed counter m, and causes each detected rotation speed counter to start counting. That is, when the time shifts from t → t + 1, the rotation speed information generation unit 90 performs the first to m-th timings at time t + 1 corresponding to the first to m-th timing signals (pulses) at time t. A signal (pulse) is output to each of the detected rotational speed counter 1 to the detected rotational speed counter m to cause each detected rotational speed counter to start counting.

Here, when the time shifts from t → t + 1, the detected rotation number counter 100 ends the rotation number information counting at the time t and starts counting the rotation number information at the time t + 1. That is, when the timing signal (pulse) of the n (1 to m) th time at time t + 1 is input from the rotation speed information generation unit 90, the detected rotation speed counter 100 receives n (1 to m) at the corresponding time t. At the same time, the counting of the rotation speed information in the cycle (time) of the timing signal (pulse) of the start is finished, and the detected rotation speed count value N _FB n (t): n = 1 to m is output to the rotation speed comparator 20 at the same time. Then, counting of the rotation speed information at time t + 1 is started.

As a result, the rotational speed comparator 20 always detects from the detected rotational speed counter 100 that N _FB 1 (t) to N _FB m (t) → N _FB 1 (t + 1) to N _FB m (t + 1) → N _FB 1 ( t + 2) to N _FB m (t + 2) and the count value of the detected rotation speed information are input.

  As described above, the rotation speed information generation unit outputs the timing signal (pulse) to the detected rotation speed counter, and causes the detected rotation speed counter 100 to count the rotation speed information indicating the rotation speed of the motor 50.

  FIG. 5 is a diagram for explaining the relationship between the operation of the detected rotation speed counter and the operation of the rotation speed comparator.

  The detected rotation speed counter 100 counts the rotation speed information at a timing when the potential of the output voltage, which is a signal indicating the rotation speed of the motor 50, becomes the same potential (match) at each reference potential at an arbitrary time t-1. I do.

Specifically, first, as shown in FIG. 5A, the detected rotation speed counter 100 determines that the output voltage, which is a signal indicating the rotation speed of the motor 50, is, for example, VFG2 at time t−1 as the first reference potential. When the reference potential coincides with the reference potential, the reference potential shifts to the next level and causes the detected rotational speed counter 1 to start counting the detected rotational speed information (detected rotational speed count value N _FB 1 (t−1)).

When the output voltage, which is a signal indicating the rotation speed of the motor 50, coincides with the next reference potential at time t-1, the detected rotation speed counter 100 shifts to the next next level and detects rotation. The number counter 2 starts counting the detected rotation number information (detected rotation number count value N _FB 2 (t−1)). Thereafter, similarly, the detected rotational speed counters 3 to m start counting the detected rotational speed information (detected rotational speed count values N _FB 3 (t−1) to N _FB m (t−1)).

Next, when the detected rotational speed counter 100 reaches time t, when the output voltage, which is a signal indicating the rotational speed of the motor 50, matches VFG2 at time t, the detected rotational speed counter 1 detects the detected rotational speed at time t-1. The counting of the number information is terminated and output to the rotation speed comparator 20 as N _FB 1 (t−1). At the same time, the detected rotational speed counter 100 causes the detected rotational speed counter 1 to start counting the detected rotational speed information at time t. Thereafter, similarly, the detected rotation speed counter 100 causes the detected rotation speed counters 2 to m to finish counting the detected rotation speed information at the time t−1, so that N _FB 2 (t−1) to N _FB m (t -1) is output to the rotation speed comparator 20. At the same time, the detected rotational speed counter 100 causes the detected rotational speed counters 2 to m to start counting the detected rotational speed information at time t.

Next, as shown in FIG. 5 (b), the rotation speed comparator 20 has an arbitrary detected rotation speed count value N _FB 1 (t−1) to N counted by the detected rotation speed counter 100 at time t−1. _FB m (t−1) is compared with the target rotational speed count value N _EXC counted by the target rotational speed holding unit 10.

The rotational speed comparator 20 compares the detected rotational speed count value N _FB n (t): n = 1 to m with the target rotational speed count value N _EXC as shown in FIG. Alternatively, the deceleration command DE is output to the acceleration command generation unit 30. Specifically, the rotation speed comparator 20 sets the cycle of the motor 50 as the target when N _FB 1 (t−1),..., N _FB m (t−1) <N _EXC. Since the motor 50 is smaller than the cycle and faster than the target rotational speed, the error is output as a deceleration command DE. In the opposite case, an acceleration command AC is output.

As described above, the detected rotational speed counter 100 and the rotational speed comparator 20 operate.
As described above, according to the first embodiment, conventionally, the rotation speed correction by the acceleration command AC and the deceleration command DE can be performed only once in one cycle of the output voltage by the Hall element, whereas the output by the Hall element is performed. It is possible to perform the number of times (m times) corresponding to a preset division number n during one period of the voltage. In other words, according to the first embodiment, m number of rotation speed correction timings can be realized even in one cycle of the output voltage by the Hall element. Compared with the prior art, the rotation speed is reduced to 1 / m according to the division number n. Can be detected. Thereby, even if it is the output voltage using a Hall element, the resolution of the real-time rotational speed information used for rotational speed control of the motor 50 can be raised. Therefore, it is possible to realize the motor control device 200 that enables stable control even in a low-speed rotation region in which control resolution is too rough and control is unstable in the conventional method.

  As described above, according to the motor control device 200 in the first embodiment, it is possible to perform stable rotation speed control even with a low-speed rotation and with a low-resolution rotation detection sensor, and high-grade components such as a rotary encoder are not required. That is, cost reduction can be achieved.

  In the example shown in FIG. 4, the description is made with n = 8 divisions and m = 12, but it is needless to say that the present invention is not limited to this.

  In the first embodiment, the description is focused on the behavior of one Hall element, but the same applies to a plurality of Hall elements. Therefore, in the motor control device 200 according to the first embodiment, n number of rotation speed correction timings can be realized even in one cycle of the output voltage for each number of the plurality of hall elements provided. Furthermore, it can be secured.

  In the first embodiment, a three-phase brushless motor is assumed to be described as three inputs from the driver 40 to the motor 50. However, the present invention is not limited to this. The present invention claims to stably control the rotational speed, and does not limit the type of motor such as a brushless motor, a DC brush motor, or a stepping motor.

  If the amplitude of the output voltage indicated by the signal output from the FG 60 is clear in advance, the sample and hold unit 70 is not necessarily provided. In that case, instead of the sample-and-hold unit 70, a holding unit that holds a value between peaks and valleys of the output voltage may be provided. Alternatively, a plurality of reference potentials may be set in advance in the 1 / n-divided reference potential generation unit 80 and used.

Further, the waveform of the output voltage indicated by the signal output from the FG 60 need not be a sine wave as described above. For example, even if the waveform is distorted as shown in FIG. 6, the same effect can be obtained if the waveform has a period corresponding to the rotation speed of the motor 50. That is, if V _P1 and V _P2 that have a period and peak values of peaks and valleys can be calculated, a plurality of reference potentials can be generated from the peak values of peaks and valleys V _P1 and V _P2 , so that rotation occurs. The resolution of numerical information can be increased.

  For example, if the magnetized state (individual SN) of the rotor 1100 varies, the waveform of the output voltage output from the FG 60 may vary in amplitude and the like although it has periodicity. Hereinafter, this case will be described as a modification.

(Modification)
FIG. 7 is a diagram for explaining a case where the waveform of the output voltage varies. FIG. 7 shows an example when the waveform of the signal (output voltage) output from the FG 60 has variations. That is, the output voltage shown in FIG. 7 shows a voltage waveform having a period corresponding to the rotation speed of the motor 50, but has a variation in amplitude (not shown, but may be a duty variation). Here, for example, FIG. 7 shows a case where a waveform 1 having a cycle F1, a waveform 2 having a cycle F2, and a waveform 3 having a cycle F3 are included as waveforms showing amplitude variations in one waveform having a cycle F of one rotation of the rotor. .

  Also in this case, the resolution of the rotational speed information can be increased by using the same method as in the first embodiment. That is, the amplitude of each of waveform 1, waveform 2, and waveform 3 is sampled and held by the sample and hold unit 70, and the reference potential is determined for each of waveform 1, waveform 2, and waveform 3. Then, for each period F of the continuous output voltage, the timing coincident with the reference potential in each of the waveform 1, the waveform 2 and the waveform 3 may be counted by the detected rotation number counter 100 as the rotation number information.

In that case, for example, F ₁₁ (t-1), F ₁₂ (t-1), F ₂₁ (t-1), F ₂₂ (t-1), F ₂₃ (t-1), F ₂₄ (t-1) ) And F ₃₁ (t−1), it is possible to have seven rotation speed correction timings even for one rotation of the output voltage having a variation in waveform.

  Note that the number of reference potentials in each of the waveform 1, the waveform 2, and the waveform 3 is not limited to the above example, and may be arbitrarily determined.

  Further, the reference potential may be determined only by the waveform 1. That is, the reference potential may be determined based on the waveform 1 having the minimum amplitude, and the determined reference potential may be used for the waveform 2 and the waveform 3 as well. In any case, a similar effect is obtained in that a rotation speed correction timing of 2 or more can be obtained even in one cycle of an output voltage having a waveform variation.

  As described above, according to the first embodiment, for example, even if the magnetized state of the motor varies and the waveform of the output voltage varies, the rotational speed of the motor 50 is set to the periodic output voltage. If it can be detected, the rotational speed correction can be performed two or more times during one cycle of the output voltage in one rotation of the rotor.

(Embodiment 2)
In the second embodiment, application products configured using the motor control device 200 according to the first embodiment will be described with some examples.

  FIG. 8 is a diagram showing an overview of a washing machine including the motor control device according to the present invention. The washing machine illustrated in FIG. 8 includes, for example, a motor 50, a motor control device 200, and a stirring body 201. Elements similar to those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The driving of the motor 50 unique to the washing machine may be, for example, that high torque and low-speed rotation are required in the washing mode, and low torque and high-speed rotation are required in the dewatering mode. Thus, in the washing machine, the necessary torque changes with the rotation speed of the motor 50 according to the operation mode. In the washing mode, since the laundry 202 is stirred by the stirring body 201, the load applied to the motor 50 changes due to the entanglement of the laundry 202 or the like.

  Therefore, by providing the washing machine shown in FIG. 8 with the motor control device 200, a washing machine capable of stably controlling the motor 50 at an arbitrary number of rotations can be realized.

  In addition, you may apply the motor drive device which concerns on this invention besides a washing machine. For example, the present invention can be applied to general home appliances including a motor such as an air conditioner, a refrigerator, and a vacuum cleaner.

  FIG. 9 is a view showing an overview of a printer provided with a motor drive device according to the present invention. The printer shown in FIG. 9 includes, for example, a motor 50, a motor control device 200, a photosensitive drum 211, and a paper feed mechanism 212. Elements similar to those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 9, in the printer, the power of the motor 50 is used to rotate the photosensitive drum 211 and the paper feed mechanism 212. There are various types of paper 213 that can be printed by the printer, such as high-quality paper, OHP foil, and envelopes. Although recent printers have several stages of rotational speed setting and low speed rotational stages, there is a growing need for motor driving at further low speeds. Therefore, by providing the motor control device 200 in the printer shown in FIG. 9, it is possible to realize a printer that can stably control the motor 50 at an arbitrary rotation speed.

  Note that the motor control device according to the present invention may be applied to devices other than printers. For example, the present invention can be applied to general office equipment including a motor such as a copying machine and a shredder apparatus.

  FIG. 10 is a diagram showing an overview of an electric vehicle equipped with the motor drive device according to the present invention. For example, in an electric vehicle equipped with a motor 50 including a hybrid car, naturally, stability at an arbitrary motor 50 speed is required. Therefore, as shown in FIG. 10, by providing a motor control device 200 in an electric vehicle, an electric vehicle capable of stably controlling the motor 50 at an arbitrary number of rotations can be realized.

  The motor drive device according to the present invention may be applied to other than electric vehicles. For example, the present invention can be applied to all mobile objects including a motor as a power source, such as an electric motorcycle, an electric assist bicycle, a train, and an airplane.

  As mentioned above, although the motor control apparatus and the motor control method of this invention were demonstrated based on embodiment, this invention is not limited to this embodiment. Unless it deviates from the meaning of this invention, the form which carried out the various deformation | transformation which those skilled in the art can think to this embodiment, and the structure constructed | assembled combining the component in different embodiment is also contained in the scope of the present invention. .

  INDUSTRIAL APPLICABILITY The present invention can be used for a motor control device and a motor control method, and in particular, home appliances such as an air conditioner, a washing machine, a refrigerator, and a vacuum cleaner, office equipment such as a copying machine and a printer, an electric hybrid bicycle, and a hybrid The motor control device and the motor control method can be used in a product field in which a wide rotational speed range including a low-speed rotational speed is required to be realized with a low-cost rotational speed detection sensor, such as a moving body such as an automobile.

10 target rotation speed holding unit 20, 1020 rotation speed comparator 30, 1030 acceleration command generation unit 40, 1040 driver 50, 1050 motor 60, 1060 FG
70 Sample / Hold Unit 80 1 / n Division Reference Potential Generation Unit 90, 1001 Rotation Number Information Generation Unit 100, 1002 Detection Rotation Number Counter 200, 1000 Motor Controller 201 Stirrer 211 Photosensitive Drum 212 Paper Feed Mechanism 213 Paper 1100 Rotor 1101 Motor board 1102 FG pattern 1202 Hall element

Claims (9)

A motor control device for controlling the rotational speed of a motor,
A rotational speed detection unit for detecting an output voltage having a cycle according to the rotational speed of the motor;
A reference potential holding unit that holds two or more reference potentials based on the value of the output voltage;
A rotation speed measurement unit that measures each reference potential cycle in which the output voltage is the same as each of the two or more reference potentials between successive cycles of the output voltage as information on the rotation speed of the motor;
A rotational speed comparator that compares information about the rotational speed of the motor detected by the rotational speed measurement unit with information about the rotational speed that is a target of the motor;
An acceleration command generator for generating an acceleration instruction based on the comparison result of the rotation speed comparator;
A motor control device comprising: a driver that controls the number of rotations of the motor by driving the motor according to the acceleration instruction generated by the acceleration command generation unit. The reference potential holding unit is
A sample-and-hold unit that samples and holds voltage values of peaks and valleys in the output voltage detected by the rotation number detection unit;
Dividing a peak-to-peak value obtained from the sampled and held voltage value by a predetermined number of two or more, and generating and holding the two or more reference potentials using the divided peak-to-peak value The motor control device according to claim 1, further comprising a reference potential generation unit. 3. The motor control device according to claim 2, wherein the division reference potential generation unit divides the peak-to-peak value equally into two or more preset numbers. The reference potential holding unit is
The motor control device according to claim 1, wherein two or more reference potentials based on the value of the output voltage are input in advance. The motor control device further includes:
The motor control device according to claim 1, further comprising a target rotation speed holding unit that holds a rotation speed that is a target of the motor as a target cycle corresponding to the rotation speed. The rotational speed measuring unit is
A signal output unit that outputs a signal each time the output voltage becomes equal to each of the two or more reference potentials;
The detection rotation number counter which measures each said reference electric potential period by counting the said signal output from the said signal output part independently within the period of the said output voltage is provided. The motor control device according to item. The rotational speed measuring unit is
The motor control device according to claim 1, wherein the number of the reference potential periods greater than the number of the two or more reference potentials is measured. The acceleration command generator
Based on the comparison result of the rotation speed comparator, if the reference potential cycle is longer than the cycle corresponding to the target rotation speed of the motor, an acceleration instruction for increasing the rotation speed of the motor is generated, and the reference The motor control according to any one of claims 1 to 7, wherein when the potential cycle is shorter than a cycle corresponding to a target rotational speed of the motor, a deceleration instruction to slow down the rotational speed of the motor is generated. apparatus. A motor control method for controlling the rotational speed of a motor,
A rotational speed detection step of detecting an output voltage having a cycle according to the rotational speed of the motor;
A reference potential holding step of holding two or more reference potentials based on the value of the output voltage;
A rotation speed measurement step of measuring each reference potential cycle in which the output voltage is equal to each of the two or more reference potentials as information relating to the rotation speed of the motor between successive cycles of the output voltage;
A rotation speed comparison step for comparing information on the rotation speed of the motor detected in the rotation speed measurement step with information on the rotation speed to be a target of the motor;
An acceleration command generation step for generating an acceleration instruction based on the comparison result in the rotation speed comparison step;
A control step of controlling the number of revolutions of the motor by driving the motor according to the acceleration instruction generated in the acceleration command generation step.

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