JP2018121501A - Motor control device and motor control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor control device that is able to determine whether a three-phase motor is in a step-out state or not.SOLUTION: A motor control device 1 comprises: a detecting section 40 that, in a non-electric-conduction period in which both the high-side switching element QH and low-side switching element QL of one of three-pairs of arm parts A are closed, detects the number of revolutions of a three-phase motor M after the end of a masking period set shorter than the non-electric-conduction-period right after the start of the non-electric-conduction-period; a revolution number determining section 50 that determines whether the number of revolutions of the three-phase motor M detected by the detecting section 40 is equal to or higher than a preset number of revolutions or not; a shortening section 60 that, in a case where the revolution number determining section 50 determines that the number of revolutions of the three-phase motor M is equal to or higher than the preset number of revolutions, the timing of the ending of the masking period is made early to shorten the masking period; and a determining section 70 that determines whether the three-phase motor M is in a step-out state or not in accordance with a change in a detection result of the detecting section 40 in a case where the masking period is shortened.SELECTED DRAWING: Figure 1

Description

  The present invention provides a high-side switching element and a low-side switching element connected in series between a first power supply line and a second power supply line connected to a potential lower than the potential of the first power supply line. The present invention relates to a motor control device for driving a three-phase motor by controlling an inverter having three sets of arm portions, and to such a motor control method.

  Conventionally, while driving a three-phase brushless motor (hereinafter referred to as “three-phase motor”), the rotation of the three-phase motor is detected without using a rotation sensor, and further, it is determined whether the three-phase motor is out of step. Technology has been used. As this type of technology, there is one described in Patent Document 1 whose source is shown below.

  The sensorless control device described in Patent Document 1 calculates the angular velocity of the primary magnetic flux of the three-phase motor from the phase voltage and phase current of the three-phase motor, and the calculated angular velocity of the primary magnetic flux indicates that the three-phase motor rotates normally. The step-out is detected based on whether or not the value falls within the range of values shown.

Japanese Patent Laid-Open No. 11-8990

  Here, when a three-phase motor is used as a power source of an electric pump, for example, the load varies depending on the presence or absence of liquid. When a control device (sensorless control device) drives such a three-phase motor with a variable load, the rotational speed increases rapidly if there is no load in the normal rotation state, but it is out of step. Even so, it shows a detection result in which the number of rotations rapidly increases, and it is difficult to accurately distinguish whether the rotation is in a normal state or in a step-out state.

  Therefore, there is a need for a motor control device that can accurately determine whether or not a three-phase motor is out of step, and such a motor control method.

  A characteristic configuration of the motor control device according to the present invention is that a high power supply connected in series between a first power supply line and a second power supply line connected to a potential lower than the potential of the first power supply line. A motor control device for driving a three-phase motor by controlling an inverter having three arm portions each having a side switching element and a low side switching element, and one arm portion of the three arm portions has In the non-energization period in which both the high-side switching element and the low-side switching element are in the open state, the three-phase phase is set immediately after the mask period set in a period shorter than the non-energization period immediately after the start of the non-energization period. A detection unit for detecting the rotation speed of the motor, and whether the rotation speed of the three-phase motor detected by the detection unit is equal to or higher than a preset rotation speed When the rotation speed determination unit and the rotation speed determination unit determine that the rotation speed of the three-phase motor is equal to or higher than the preset rotation speed, the timing to end the mask period is advanced. A determination unit that determines whether or not the three-phase motor is in a step-out state according to a change in a detection result of the detection unit when the mask period is shortened, It is in the point equipped with.

  With such a characteristic configuration, depending on the three-phase motor, the rotational speed in the step-out state in which the sensorless control is commutated at high speed and the rotational speed in the normal rotation in the no-load state are approximately the same. When the rotation speed of the three-phase motor reaches the normal rotation speed with no load, the sensorless control mask period is shortened and the mask period is released earlier to increase the rotation speed during step-out. Thus, it can be distinguished from normal rotation in a no-load state. Therefore, in a BEMF (back electromotive force) type sensorless motor, it is possible to accurately determine whether or not the three-phase motor is in a step-out state, and to easily detect the step-out state.

  The determination unit may be out of step when the change in the detection result of the detection unit indicates that the number of rotations of the three-phase motor has increased in response to the shortening of the mask period. Is preferable.

  With such a configuration, in the sensorless control, the step-out state and the normal rotation state in the no-load state can be determined only by the rotation speed.

  The motor control method according to the present invention is characterized in that the motor control method is connected in series between a first power supply line and a second power supply line connected to a potential lower than the potential of the first power supply line. A motor control method for driving a three-phase motor by controlling an inverter having three arm portions each having a high-side switching element and a low-side switching element, wherein one arm portion of the three arm portions In the non-energization period in which both the high-side switching element and the low-side switching element have an open state, immediately after the start of the non-energization period and after the end of the mask period set in a period shorter than the non-energization period A detection step for detecting the rotation speed of the three-phase motor, and the rotation speed of the three-phase motor detected in the detection step are set in advance. A rotation speed determination step for determining whether or not the rotation speed is equal to or greater than the rotation speed; and when the rotation speed determination step determines that the rotation speed of the three-phase motor is equal to or greater than the preset rotation speed, the mask period Whether or not the three-phase motor is in a step-out state in accordance with a shortening step of shortening the mask period by ending the end timing of the process and a change in a detection result in the detection step when the mask period is shortened And a determination step for determining whether or not.

  Compared with the motor control device as the object of the present invention described above, the motor control method configured in this way is not substantially different in characteristic configuration, and the above-described operational effects can be obtained.

  In the determination step, the three-phase motor is out of step when the change in the detection result in the detection step indicates that the number of rotations of the three-phase motor has increased in response to the shortening of the mask period. Is preferable.

  Compared with the motor control device as the object of the present invention described above, the motor control method configured in this way is not substantially different in characteristic configuration, and the above-described operational effects can be obtained.

It is the block diagram which showed the structure of the motor control apparatus typically. It is explanatory drawing of an electricity supply period and a non-energization period. It is a determination flow of whether or not a step-out state.

  The motor control device according to the present invention is configured to be able to accurately determine whether or not the three-phase motor is in a step-out state. Hereinafter, the motor control apparatus 1 of this embodiment is demonstrated.

  FIG. 1 is a block diagram schematically showing the configuration of the motor control device 1. The motor control device 1 includes a PWM control unit 10, a driver 20, an inverter 30, a detection unit 40, a rotation speed determination unit 50, a shortening unit 60, and a determination unit 70.

  The PWM control unit 10 generates a PWM signal and performs PWM control on an inverter 30 described later. Since the PWM control by the PWM signal is known, the description thereof is omitted.

  The driver 20 is provided between the PWM control unit 10 and the inverter 30 and receives a PWM signal generated by the PWM control unit 10. The driver 20 improves the drive capability of the input PWM signal and outputs it to the inverter 30.

  The inverter 30 drives the three-phase motor M by controlling the current flowing through the three-phase motor M. In the present embodiment, the three-phase motor M is exemplified by a star connection as shown in FIG. 1, but may be a delta connection.

  The inverter 30 includes a high-side switching element connected in series between the first power supply line 2 and the second power supply line 3 connected to a potential lower than the potential of the first power supply line 2. Three arm portions A each having QH and low-side switching element QL are provided. The first power supply line 2 is a cable connected to the power supply V. The second power supply line 3 connected to a potential lower than the potential of the first power supply line 2 is a cable to which a potential lower than the output voltage of the power supply V is applied. In this embodiment, the cable is grounded. Corresponds.

  In the present embodiment, the high side switching element QH is configured using a P-MOSFET, and the low side switching element QL is configured using an N-MOSFET. The high side switching element QH has a source terminal connected to the first power supply line 2 and a drain terminal connected to the drain terminal of the low side switching element QL. The source terminal of the low side switching element QL is connected to the second power supply line 3. The arm part A is constituted by the high-side switching element QH and the low-side switching element QL connected as described above, and the inverter 30 includes three sets of the arm part A.

  The gate terminals of the high-side switching element QH and the low-side switching element QL are connected to the driver 20, and the above-described PWM signal with improved drive capability is input. Further, the drain terminal of the high-side switching element QH of each arm part A is connected to three terminals of the three-phase motor M, respectively.

  In the non-energization period in which both the high-side switching element QH and the low-side switching element QL included in one arm part A of the three sets of arm parts A are in the open state, the detection unit 40 immediately after the start of the non-energization period. The rotation speed of the three-phase motor M is detected after the mask period set in a period shorter than the non-energization period.

  Here, FIG. 2 shows an explanatory diagram of the energization period and the non-energization period. FIG. 2 shows the conduction state of the high-side switching element QH and the low-side switching element QL constituting one arm part A among the three sets of arm parts A included in the inverter 30. As described above, the high-side switching element QH and the low-side switching element QL are controlled by the PWM signal. However, in this embodiment, the high-side switching element QH is composed of a P-MOSFET, so that the PWM signal is the highest in FIG. The waveform in the upper part is inverted. FIG. 2 also shows voltage waveforms at locations indicated by VU in FIG.

  The energization period is a period in which one of the high-side switching element QH and the low-side switching element QL included in one arm part A of the three sets of arm parts A is closed. “One of the high-side switching element QH and the low-side switching element QL is in a closed state” means that one of the high-side switching element QH and the low-side switching element QL is in a conductive state. Specifically, in the example of FIG. 2, the period from time t1 to time t2, the period from time t3 to time t4, the period from time t5 to time t6, and the period from time t7 to time t8. Equivalent to. These periods are called energization periods because one of the high-side switching element QH and the low-side switching element QL included in one arm part A of the three sets of arm parts A is energized. The

  The non-energization period is a period in which both the high-side switching element QH and the low-side switching element QL included in one arm part A of the three sets of arm parts A are open. “Both the high-side switching element QH and the low-side switching element QL are in the closed state” means that both the high-side switching element QH and the low-side switching element QL are in a non-conductive state. Specifically, in the example of FIG. 2, the period from time t2 to time t3, the period from time t4 to time t5, and the period from time t6 to time t7 correspond. These periods are referred to as non-energization periods because both the high-side switching element QH and the low-side switching element QL included in one arm part A of the three sets of arm parts A are not energized. The

  In such a non-energizing period, a surge occurs immediately after the transition from the energizing period. Therefore, the mask period is set in a period shorter than the non-energization period immediately after the start of the non-energization period. “The mask period is set in a period shorter than the non-energization period” means that the mask period is not set over the entire non-energization period but only in a part of the non-energization period. Means. In particular, the mask period starts after position detection (zero cross detection) and is released before the next position detection. FIG. 2 shows an example of the mask period. The detection unit 40 can detect the number of rotations of the three-phase motor M after the mask period ends without being affected by the surge.

  The detection unit 40 detects the position of the rotor (not shown) of the three-phase motor M based on the motor current flowing through the three-phase motor M. In the present embodiment, the detection unit 40 is connected to a cable connecting the drain terminal of the high-side switching element QH of each arm unit A and each of the three terminals of the three-phase motor M via the resistor R. Connected. The neutral point of the star connection is also connected via a resistor R. By being connected in this way, the detection unit 40 detects the motor current and detects (calculates) the position of the rotor. Since this detection is publicly known, a description thereof will be omitted. The detection unit 40 detects the rotation speed of the three-phase motor M based on the position of the rotor. The detection result of the detection unit 40 is transmitted to the PWM control unit 10, and the PWM control unit 10 uses the PWM control. The detection result of the detection unit 40 is also transmitted to a rotation speed determination unit 50 described later.

  In the non-energization period in which both the high-side switching element QH and the low-side switching element QL included in one arm part A of the three sets of arm parts A are in the open state, the non-energization is performed immediately after the start of the non-energization period. The step of detecting the rotation speed of the three-phase motor M after the end of the mask period set in a period shorter than the period corresponds to a detection step in the motor control method.

  The rotation speed determination unit 50 determines whether the rotation speed of the three-phase motor M detected by the detection unit 40 is equal to or higher than a preset rotation speed. As described above, the detection unit 40 detects the rotation speed of the three-phase motor M and transmits the detection result to the rotation speed determination unit 50. “Preset rotation speed” is the rotation speed when the three-phase motor M is in a no-load state. Alternatively, it may be the rotational speed when the load of the three-phase motor M is in a light load state in which the load is not more than a predetermined value. Such a rotational speed is preset and stored in the rotational speed determination unit 50 or a storage unit (not shown). Therefore, the rotation speed determination unit 50 is configured such that the rotation speed of the three-phase motor M transmitted from the detection unit 40 is preset, and the stored three-phase motor M is in a no-load state (or a light load state). It is determined whether or not the number of rotations is equal to or greater than. The determination result of the rotation speed determination unit 50 is transmitted to the shortening unit 60 described later.

  The step of determining whether or not the rotation speed of the three-phase motor M detected in such a detection step is equal to or higher than a preset rotation speed corresponds to the rotation speed determination step in the motor control method.

Here, the rotation speed in the step-out state where the commutation occurs at high speed can be calculated using the following equation (1).
T60 = Tm + Tb (1)
However, T60 is the time between zero cross and zero cross at the time of step-out, Tm is the mask release time, and Tb is the minimum time required for position detection determination. As can be seen from the equation (1), by shortening Tm, T60 can be shortened, and the rotation speed at the time of step-out can be increased.

  Therefore, when the rotational speed determination unit 50 determines that the rotational speed of the three-phase motor M is equal to or higher than the rotational speed set in advance, the shortening unit 60 sets the mask period by accelerating the end timing at which the mask period ends. Shorten. As described above, the determination result of the rotation speed determination unit 50 is transmitted to the shortening unit 60. Therefore, “when the rotational speed determination unit 50 determines that the rotational speed of the three-phase motor M is equal to or higher than the predetermined rotational speed” is detected by the detection unit 40 based on the determination result by the rotational speed determination unit 50. It means that the determination result indicates that the rotation speed of the three-phase motor M is equal to or higher than a preset rotation speed. In addition, as described above, the mask period is a period that is set to start immediately after the transition from the energization period to the non-energization period. Therefore, when the determination result by the rotation speed determination unit 50 is a determination result indicating that the rotation speed of the three-phase motor M detected by the detection unit 40 is equal to or higher than the rotation speed set in advance. The mask period set to start immediately after the transition from the energization period to the non-energization period is shortened so as to end early.

  When it is determined in such a rotational speed determination step that the rotational speed of the three-phase motor M is equal to or higher than a predetermined rotational speed, the step of shortening the mask period by accelerating the end timing at which the mask period ends is: This corresponds to a shortening step in the motor control method.

  The determination unit 70 determines whether or not the three-phase motor M is in a step-out state according to a change in the detection result of the detection unit 40 when the mask period is shortened. Information indicating that the mask period has been shortened by the shortening unit 60 is transmitted to the determination unit 70. Based on this information, the determination unit 70 can recognize that the mask period has been shortened. On the other hand, even when the mask period is shortened, the detection unit 40 described above continuously detects the rotation speed of the three-phase motor M, and the rotation speed determination unit 50 rotates the rotation speed of the three-phase motor M set in advance. It is determined whether the number is greater than or equal to the number. After the mask period is shortened, the determination unit 70 determines whether the three-phase motor M is based on the determination result of whether or not the rotation number of the three-phase motor M is equal to or higher than the rotation number set in advance by the rotation number determination unit 50. It is determined whether or not it is in a step-out state.

  The step of determining whether or not the three-phase motor M is in a step-out state according to the change in the detection result in the detection step when the mask period is shortened corresponds to the determination step in the motor control method.

  In particular, in the present embodiment, the determination unit 70 removes the three-phase motor M when the change in the detection result of the detection unit 40 indicates that the number of rotations of the three-phase motor M has increased in accordance with the shortening of the mask period. It is determined that the key is in an adjusted state. That is, after the mask period is shortened by the shortening unit 60, the determination result of the rotation speed determination unit 50 indicates that the rotation speed of the three-phase motor M is higher than the rotation speeds before (the rotation speed before the mask period is shortened). When it shows that it did, the determination part 70 determines with the three-phase motor M being a step-out state.

  In this way, the determination step determines that the three-phase motor M is out of step when the change in the detection result in the detection step indicates that the number of rotations of the three-phase motor M has increased in accordance with the shortening of the mask period. It becomes a step to do.

  Next, the process for determining whether or not the motor control device 1 is in a step-out state will be described with reference to the flowchart of FIG. First, it is determined by the rotational speed determination unit 50 whether or not the three-phase motor M is operating at a constant rotational speed at a predetermined rotational speed or higher (step # 01). If it is determined that the three-phase motor M is operating at a constant speed or higher (step # 01: Yes), the shortening unit 60 shortens the mask period (step # 02).

  When the number of rotations of the three-phase motor M detected by the detection unit 40 has increased after the masking period has been shortened by the shortening unit 60 (step # 03: Yes), the determination unit 70 determines that the three-phase motor It is determined that M is in a step-out state (step # 04). In step # 03, after the masking period is shortened by the shortening unit 60, the rotation speed of the three-phase motor M detected by the detection unit 40 has not increased (step # 03: No), and the three-phase If there is no change in the rotational speed of the motor M (step # 05: Yes), the determination unit 70 determines that the three-phase motor M is in a normal state (non-step-out state) (step # 06). If there is a change in the rotational speed of the three-phase motor M in step # 05 (step # 05: No), the process returns to step # 01 and continues.

[Other Embodiments]
In the above embodiment, the high-side switching element QH is configured using a P-MOSFET and the low-side switching element QL is configured using an N-MOSFET. However, the high-side switching element QH and the low-side switching element QL are It is also possible to configure using other switching elements.

  The present invention provides a high-side switching element and a low-side switching element connected in series between a first power supply line and a second power supply line connected to a potential lower than the potential of the first power supply line. The present invention can be used in a motor control device that drives an three-phase motor by controlling an inverter including three arm portions having the arm portion, and such a motor control method.

1: Motor control device 2: First power supply line 3: Second power supply line 30: Inverter 40: Detection unit 50: Revolution determination unit 60: Reduction unit 70: Determination unit A: Arm unit QH: High-side switching element QL: Low-side switching element M: Three-phase motor

Claims (4)

An arm portion having a high-side switching element and a low-side switching element connected in series between a first power supply line and a second power supply line connected to a potential lower than the potential of the first power supply line A motor control device for driving a three-phase motor by controlling an inverter comprising three sets of
In the non-energization period in which both the high-side switching element and the low-side switching element of one of the three sets of arm parts are in the open state, immediately after the start of the non-energization period, A detection unit for detecting the number of rotations of the three-phase motor after the end of the mask period set in a short period;
A rotational speed determination unit that determines whether or not the rotational speed of the three-phase motor detected by the detection unit is equal to or higher than a preset rotational speed;
A shortening unit that shortens the mask period by advancing the end timing at which the mask period ends when the rotation number determination unit determines that the rotation number of the three-phase motor is equal to or greater than the preset rotation number. When,
A determination unit that determines whether or not the three-phase motor is in a step-out state according to a change in a detection result of the detection unit when the mask period is shortened;
A motor control device comprising:   The determination unit determines that the three-phase motor is in a step-out state when a change in a detection result of the detection unit indicates that the number of rotations of the three-phase motor has increased in response to the shortening of the mask period. The motor control device according to claim 1. An arm portion having a high-side switching element and a low-side switching element connected in series between a first power supply line and a second power supply line connected to a potential lower than the potential of the first power supply line A motor control method for driving a three-phase motor by controlling an inverter comprising three sets of
In the non-energization period in which both the high-side switching element and the low-side switching element of one of the three sets of arm parts are in the open state, immediately after the start of the non-energization period, A detection step of detecting the number of revolutions of the three-phase motor after the end of the mask period set in a short period;
A rotational speed determination step for determining whether the rotational speed of the three-phase motor detected in the detection step is equal to or higher than a predetermined rotational speed;
A shortening step of shortening the mask period by advancing the end timing at which the mask period ends when it is determined in the rotational speed determination step that the rotational speed of the three-phase motor is equal to or higher than the preset rotational speed. When,
A determination step of determining whether or not the three-phase motor is in a step-out state according to a change in a detection result in the detection step when the mask period is shortened;
A motor control method comprising:   The determination step determines that the three-phase motor is in a step-out state when a change in the detection result in the detection step indicates that the number of rotations of the three-phase motor has increased in response to the shortening of the mask period. The motor control method according to claim 3.

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