JP4654124B2 - Control method for permanent magnet synchronous motor drive device and permanent magnet synchronous motor drive device using the same - Google Patents

Description

  The present invention relates to a technique for driving a permanent magnet synchronous motor.

  Patent Document 1 discloses an apparatus for driving a permanent magnet synchronous motor. Patent Document 1 relates to a technique for quickly detecting an open phase of an inverter output with a simple configuration.

JP 2004-289909 A (page 3-4, FIG. 2)

  In some cases, including the above-mentioned Patent Document 1, it is desired to detect an open phase among a plurality of phases output from the drive device for the electric motor to be driven.

  With respect to the detection of the phase loss, there is no output from the driving device in the phase that has lost the phase, so that no current flows. Therefore, by measuring the current flowing in each phase, it is possible to know the presence or absence of a phase failure.

  Note that the current is difficult to measure while the electric motor is rotating, and is measured before starting or at the time of stopping. In the state where the electric motor is stopped, since no output is output from the normal drive device, it is conceivable to output some detection output.

  However, when the detection output is output when the motor is stopped, it is necessary to output the detection output within a current value allowed by the switching element of the output stage of the drive device or within an allowable period. It becomes a problem.

  In solving the above-mentioned problems and the like, the points to be noted are explained below, and the countermeasures are described.

  The first is to set the magnitude of the current value allowed by the switching element in the output stage of the driving device when outputting the detection output. For this, the control unit adjusts the voltage by current control with a current value of about 10% of the rated value of the switching element in the output stage as a target value, thereby protecting the switching element in the output stage. Enable detection.

  The second is to improve the detection accuracy of phase loss detection. Normally, current detection including these phase loss detections is performed by the current detection unit and the control unit. Current detection is also performed at a certain sampling period. The detected current value for the above detection signal usually includes some unnecessary components such as noise and noise. Therefore, it is preferable to reduce the influence of these unnecessary components. In consideration of this, the detection signal is output for a period of about 10 times the sampling period for current detection.

  The third is a detection output method that enables detection of phase loss. Generally, there are a 180-degree energization method and a 120-degree energization method as energization methods during operation of the permanent magnet synchronous motor. In the present invention, an open phase is detected by using an output method of 120-degree conduction. In the former case, the degree of freedom of the phase at which energization is possible increases, but in order to drive three or more upper and lower arm switching elements of the reverse conversion unit, if any one of the switching elements is destroyed, the other Since current flows through these two switching elements, it is difficult to detect the phase loss. In the latter case, for example, in the case of a three-phase output, the energization phase is limited to six energization patterns every 60 degrees, that is, one rotation, but only one switching element of the upper and lower arms of the inverse conversion unit is driven. . Therefore, when one of the switching elements is broken, current does not flow, and therefore phase loss can be detected.

  Fourth, when the detection output is output to the electric motor, the rotor of the electric motor may rotate in some cases.

  On the other hand, in the case of three-phase output, by using a 120-degree energization method energization pattern, the energization pattern that is output to the motor to generate normal rotational torque and the holding torque are detected by energization patterns other than the generated energization pattern. By outputting the voltage, it is possible to detect an open phase without rotating the electric motor. In the case of a three-phase output, the energization is 6 patterns, but two of them are a rotational torque generation pattern and a holding torque generation pattern. Therefore, by energizing the four patterns excluding these two, it is possible to detect a phase loss by energizing the combination of the upper arm and the lower arm that are not in the short-circuit mode of the inverse conversion unit.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the drive device which drives the electric motor which improved reliability rather than before.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention, FIG. 2 is a flowchart showing a control procedure of the embodiment, and FIGS. 3 to 5 illustrate energization patterns for explaining the embodiment. It is a schematic diagram to do.

  In FIG. 1, power from a commercial power source 10 is converted into DC power by a forward conversion unit 20, smoothed by a smoothing unit 30, and then input to an inverse conversion unit 40, and the inverse conversion unit 40 includes a PWM signal generation unit 50. Is output to the permanent magnet synchronous motor 70 after being converted to alternating current power based on the PWM signal from. At this time, the PWM signal generator 50 is controlled by the controller 60. The magnetic pole position detector 80 detects the position of the magnetic pole of the permanent magnet synchronous motor.

  Next, the detection procedure of the embodiment of the present invention will be described with reference to the flowchart shown in FIG.

  Usually, after detecting the position of the magnetic pole of the permanent magnet synchronous motor by the magnetic pole position detector 80 or the like, the phase loss detection of this embodiment is started (step 200).

  First, an energization pattern that does not generate rotational torque and holding torque in the 120-degree energization method is set as a missing phase detection energization pattern based on the position information obtained by the position detection process executed previously (step 210). One of the phase detection energization patterns is set (step 220). In the case of three-phase output, as described above, one of the four energization patterns in which the rotational torque and the holding torque are not generated in the 120-degree energization method is set.

  Next, the energization time is set (step 230), and after setting the command voltage value (step 240), output is started using current control generally called current control (step 250).

  Thereafter, a current detection process is performed (step 260), and the detected current value is integrated (step 270). Here, the current value integration process is performed in order to improve the phase loss detection accuracy, but the integration process can be eliminated.

  Next, it is compared with a preset threshold value (step 280). If it is larger than the threshold value, it is determined as normal (step 240-YES), and the output is stopped (step 320). Here, it is determined whether or not all the phase loss detection energization patterns have been completed (step 330). If not all have been completed (step 330-NO), the phase loss detection energization pattern is changed (step 340) and again. The output is started (step 250) and the detection process is continued.

  When all of the current loss detection patterns for phase loss detection have been completed (step 330-YES), it is determined that there is no phase loss and the phase loss detection process is ended (step 350).

  If the integrated current value is smaller than the preset threshold value (step 280-NO), it is determined whether the preset energization time has elapsed (step 290), and if not (step 290-NO), The detection operation is performed within the energization time.

  If the energization time has elapsed (step 290-YES), it is determined that the phase is missing (step 300), the output is stopped (step 310), and the phase loss detection process is terminated (step 350).

  Here, the energization time is provided in order to perform the detection operation in a predetermined time period in order to avoid the influence of unnecessary components such as noise and noise at the time of detection.

  Here, the phase loss detection energization pattern used in the present embodiment will be described with reference to FIGS. In the drawing, a rotor is shown inside, and a stator is shown outside, but this is described as an illustrative example.

  FIG. 3 shows a pattern example in which rotational torque is generated in the 120-degree energization method. FIG. 4 shows a pattern example in which holding torque is generated in the 120-degree energization method. In the energization patterns of FIGS. 3 and 4, the rotor may rotate, which is not preferable for use for detecting a phase loss.

  First, in FIG. 3, the magnetic flux generated in the winding of the stator located in the vicinity of the N pole in the vicinity of the magnetic pole of the rotor generates N pole magnetism so that they repel each other, and the rotor is moved to an arrow. This is a pattern in which a force (rotational torque) rotating in the direction of is generated. Actually, in the case of rotational torque, as shown in FIG. 3, it does not simply generate N pole magnetic flux, but for the sake of easy explanation, It is shown.

  Next, in FIG. 4, the winding of the stator located near the north pole of the rotor magnetic pole generates a magnetic flux of the south pole, attracting each other, and the force that the rotor rotates in the direction of the arrow. This is a pattern in which (holding torque) is generated. Actually, even in the case of the holding torque, as shown in FIG. 4, it does not simply generate the magnetic flux of the south pole, but for the sake of easy explanation, It is shown.

  On the other hand, in the energization pattern shown in FIG. 5, the magnetic flux generated by the winding of the stator located near the N pole of the rotor magnetic pole is small (in FIG. 5, this is indicated by “x” mark). Rotating torque and holding torque are not generated, so that the rotor does not rotate. Therefore, in the present embodiment, the energization pattern shown in FIG. 5 is used as the energization pattern for phase loss detection.

  In the above description, “the magnetic flux generated by the winding of the stator is small”. However, this is not only the case where no magnetic flux is generated, but the rotation torque and the holding torque are applied to the N pole of the rotor of FIG. The magnitude of magnetism may be such that it does not affect the force that generates the.

  Here, a description will be given of how the current flows in the phase loss energization pattern shown in FIG. In this energization pattern, as described above, not only rotational torque and holding torque are not generated, but also a short circuit of the switching element of the inverse conversion unit can be avoided.

The inverse conversion unit is configured by a switching element generally called an “upper arm” and a switching element called a “lower arm” connected in series. If both the upper arm and lower arm switching elements are simultaneously turned on and a current flows, both of the switching elements may be destroyed. Therefore, it is necessary to control so that they are not turned on at the same time.
This is a matter that needs to be noted even when phase loss is detected in this embodiment.

  In addition to avoiding simultaneous turning on of both the upper and lower arms, the time during which current flows through these switching elements needs to be limited to a time during which these switching elements are not destroyed.

  In order to flow the current so as to detect the phase loss with the above two conditions, it is output by the PWM signal generator that generates the PWM signal for controlling the reverse conversion unit in the permanent magnet synchronous motor drive device. An output signal similar to the PWM signal is used as a detection signal for phase loss detection. Here, in the above control, the rotational position of the electric motor 70 is detected by the position detector 80 and then input to the control unit 60 and used for control. Further, by detecting the current flowing through the shunt resistor 90, the current flowing through the electric motor 70 is detected and used in the control of the control unit 60.

  In the above embodiment, in selecting the voltage value for detection, it is assumed that the element is prevented from being destroyed when the rated value of the switching element in the output stage is exceeded, and the element is protected, and is described as about 10% of the rated value. However, the present invention is not limited to this. Accordingly, the voltage value can be different from the above value as long as it can be safely prevented from exceeding the rated value of the switching element of the output stage by considering the loss of the switching element of the output stage. .

  In the above embodiment, the detection signal is described as a period of about 10 times the sampling period for current detection in consideration of reducing the influence of unnecessary components, but the present invention is not limited to this. It is not a thing. Therefore, in the measurement of the detection signal for detection or the like, a period different from 10 times the sampling period may be used as long as the influence of unnecessary components can be reduced.

  In the above embodiment, the shunt resistor is provided in the driving device for current detection. However, the present invention is not limited to this. For example, for each of the three phases of the output lines output to the motor, It may be provided in the phase. Further, the present invention is not limited to the shunt resistor, and a current detection element called a so-called Hall element may be used.

  Although the 120-degree energization method has been described in the above embodiment, the present invention is not limited to this. For example, even in a driving method called a 180-degree energization method, phase loss can be detected using the above embodiment. However, in this case, a predetermined period during which the phase loss is detected when the motor is started is 120 degrees energization, and the 180 degrees energization is performed after the phase loss is detected with the output detection current for phase loss detection. It is necessary to perform switching control so that the motor is driven by the method.

The figure which shows the structure concerning one Example of this invention. The figure which shows the control processing concerning the Example The figure which shows the example of an electricity supply pattern in describing a present Example The figure which shows the other example of an electricity supply pattern in describing a present Example The figure which shows the example of the electricity supply pattern used for the present Example

Explanation of symbols

20: Forward conversion unit, 30: Smoothing unit 30, 40: Inverse conversion unit, 50: PWM signal generation unit, 60: Control unit, 70: Permanent magnet synchronous motor, 80: Magnetic pole position detector.

Claims (10)

A method for controlling a permanent magnet motor drive device for detecting and rotating the magnetic pole position of a permanent magnet motor,
Operation control of the permanent magnet motor by a 120 degree energization method,
Detecting the magnetic pole position of the permanent magnet motor at startup,
From the magnetic pole position of the detected the permanent magnet motor, the rotational torque for rotating the rotor, and the applied voltage pattern phase loss detection of the voltage applied to the permanent magnet motor so as not to generate a holding torque for holding the rotor Set as the energization pattern for
In the set open-phase detection energization pattern, an applied voltage is applied to the permanent magnet motor,
A detection process of the current flowing by the applied voltage is performed, and the detected current value is compared with a preset predetermined current value,
When the comparison result indicates that the detected current value is smaller than the predetermined current value, it is determined that a phase loss has occurred, and a phase failure of the permanent magnet motor is detected. Control method of drive device. A control method for a permanent magnet motor drive device according to claim 1,
A control method for a permanent magnet motor drive device, wherein a detection process for detecting the detected current value is performed for a predetermined time. A control method for a permanent magnet motor drive device according to claim 2,
  In the detection process for detecting the detected current value, a current is detected in a detection time longer than a current detection sampling period. A control method for a permanent magnet motor drive device according to claim 1,
  In the detection process for detecting the detection current value, the detection current is integrated, and the method for controlling the permanent magnet motor drive device is characterized in that: A control method for a permanent magnet motor drive device according to claim 1,
  The phase loss detection energization pattern is formed by winding a stator positioned opposite a predetermined magnetic pole of the rotor.
Holding force that does not generate the rotational force that rotates the rotor by the magnetic flux generated by the wire, and that holds the rotor by the magnetic flux generated by the stator winding located opposite to the predetermined magnetic pole of the rotor A method for controlling a permanent magnet motor drive device, wherein A forward converter for converting electric power from a commercial power source into direct current power;
A smoothing unit for smoothing the output of the forward conversion unit;
An inverse conversion unit that converts the output of the smoothing unit into alternating current power and outputs the same to a permanent magnet synchronous motor;
A PWM signal generator for generating a PWM signal for driving the inverse converter;
A control unit that detects an output current of the inverse conversion unit and controls a PWM signal generation unit;
A permanent magnet synchronous motor driving device and a magnetic pole position detector for detecting the magnetic pole position of the rotor of the permanent magnet synchronous motor,
The controller controls operation of the permanent magnet motor by a 120-degree energization method,
At startup, a voltage is applied to the permanent magnet motor for a certain period of time according to an applied voltage pattern of the voltage applied to the permanent magnet motor so as not to generate a rotating torque for rotating the rotor and a holding torque for holding the rotor. Detect the value,
The detected current value detected is compared with a predetermined current value set in advance,
The permanent magnet synchronous motor drive device according to claim 1, wherein when the comparison result is that the detected current value is smaller than the predetermined current value, it is determined that the phase is lost. The permanent magnet motor drive device according to claim 6,
A permanent magnet motor driving device, wherein a detection process for detecting the detected current value is performed for a predetermined time. The permanent magnet motor drive device according to claim 7,
In the detection process for detecting the detection current value, the current is detected in a detection time longer than the sampling period of the current detection. The permanent magnet motor drive device according to claim 6,
  In the detection process for detecting the detection current value, the detection current is integrated, and the permanent magnet motor drive device is characterized in that The permanent magnet motor drive device according to claim 6,
  The applied voltage pattern is one that does not generate a rotational force that rotates the rotor by the magnetic flux generated by the winding of the stator located opposite to the predetermined magnetic pole of the rotor, and opposite the predetermined magnetic pole of the rotor. A permanent magnet motor driving device characterized in that a holding force for holding the rotor is not generated by the magnetic flux generated in the winding of the stator located at the center.

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