JP6089845B2 - Permanent magnet synchronous motor starting method - Google Patents

Description

  The present invention relates to a method for starting a permanent magnet synchronous motor in which lubricating oil is used for a motor bearing.

  Synchronous motors (hereinafter referred to as PM motors) have advantages such as less loss because there is no copper loss in the secondary circuit compared to induction machines. However, when this is driven by a variable speed control device such as an inverter, the position of the magnetic pole needs to be detected by a position sensor or the like. However, since the position sensor has a built-in semiconductor element or optical element, it has low environmental resistance and is likely to fail. For this reason, development of a position sensorless control system is in progress.

  For example, Patent Document 1 proposes a sensorless control system for a permanent magnet type synchronous motor including a magnetic pole position estimation device.

  A PM motor that uses a lubricating oil in a motor bearing to reduce static friction because of a large thrust load is configured as shown in FIG. 5, for example. In FIG. 5, 11 is a shaft of the PM motor 10, and 12 is a bearing to which lubricating oil is supplied. In the PM motor 10 configured as shown in FIG. 5, in order to reduce the starting torque, it is necessary to attach a device such as an oil lifter device that supplies lubricating oil to the bearing 12. As a result, the size of the apparatus is increasing.

  Note that there are motors using lubricating oil for the bearings described in Patent Documents 2 and 3, for example.

Japanese Patent No. 4211133 JP 2008-261327 A Japanese Patent Laid-Open No. 7-253117

  In a PM motor that has a large thrust load and uses lubricating oil for the motor bearing to reduce static friction, the starting torque increases when the lubricating oil layer is not formed, such as when starting from a stopped state. In order for the inverter to start the motor, it is necessary to increase the starting torque. When starting, a layer of lubricating oil is gradually formed, the coefficient of static friction becomes smaller, and a sudden load change occurs. At this time, if the engine is started without a position sensor, the magnetic pole position cannot be estimated, and step-out may occur and control becomes impossible.

  The present invention solves the above-described problems, and an object of the present invention is to provide a permanent magnet type synchronous motor starting method capable of reducing starting torque in a PM motor using lubricating oil for a motor bearing. It is in.

A starting method of a permanent magnet type synchronous motor according to claim 1 for solving the above-mentioned problem is a starting method of a permanent magnet type synchronous motor in which lubricating oil is used for a motor bearing, wherein the permanent magnet is in a stopped state. A positive rotation control for generating a positive rotation torque by applying a first pulse voltage of a first phase shifted by a first angle from the initial magnetic pole position to the armature winding of the synchronous motor, and the initial magnetic pole Reverse rotation control for generating reverse rotation torque by applying a second pulse voltage equivalent to the first pulse voltage at a second phase inverted by the first angle from a position, and current stabilization It is characterized by being repeatedly executed alternately over a period.

  According to the above configuration, the bearing raceway surface is lubricated by generating a normal rotation torque and a reverse rotation torque alternately to vibrate the motor when starting a permanent magnet synchronous motor in which lubricating oil is used for a motor bearing. Since the oil layer is formed, the starting torque can be reduced.

  According to a second aspect of the present invention, there is provided a method for starting a permanent magnet synchronous motor according to the first aspect, wherein the first angle is set within 90 degrees.

  According to the above configuration, since a minute vibration is applied, the deviation from the initial magnetic pole position can be reduced, and a shock at the time of transition to the acceleration operation can be suppressed.

  According to a third aspect of the present invention, there is provided a method for starting a permanent magnet synchronous motor according to the first or second aspect, wherein the number of executions of the control with the normal rotation control and the reverse rotation control as one set is n times (n is a normal value) The first angle at the time of execution of the (n + 1) th time is set smaller than the first angle at the time of execution of (Num.).

  According to the said structure, the shift | offset | difference from an initial stage magnetic pole position can be made smaller than the case of Claim 1,2.

(1) According to the first to third aspects of the present invention, when starting a permanent magnet type synchronous motor in which lubricating oil is used for a motor bearing, a positive rotational torque and a reverse rotational torque are alternately generated to cause the electric motor to By oscillating, a lubricating oil layer is formed on the bearing raceway surface, so that the starting torque can be reduced. It also reduces the risk of sudden load changes at start-up and reduces the risk of step-out.
(2) According to the invention described in claim 2, since minute vibration is applied, the deviation from the initial magnetic pole position can be reduced, and the shock at the time of transition to the acceleration operation can be suppressed.
(3) According to the invention described in claim 3, the phase of the pulse voltage is determined so as to gradually approach the initial magnetic pole position as the number of control executions increases, so that the deviation from the initial position is made smaller. Can do.

Explanatory drawing of the pulse voltage command in the starting method of Example 1 of this invention. The time chart explaining the starting method of Example 1 of this invention. Explanatory drawing of the pulse voltage command in the starting method of Example 2 of this invention. Explanatory drawing of the pulse voltage command in the starting method of Example 3 of this invention. The block diagram which shows an example of PM motor to which this invention is applied.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. In this embodiment, for example, a positive rotation control is performed to generate a positive rotation torque by applying a pulse voltage having a phase shifted by 90 degrees from the initial magnetic pole position to a PM motor driven by an inverter, for example. After a predetermined current stabilization period, reverse rotation control is performed to generate reverse rotation torque by applying a pulse voltage having a phase that is 180 degrees different from the phase, and the forward rotation control and reverse rotation control are alternately performed. It is executed repeatedly.

  Examples 1 to 3 in which the present invention is applied to the PM motor 10 shown in FIG. 5 will be described below.

  FIG. 1 is a diagram for explaining a pulse voltage command (voltage vector) output from an inverter in the first embodiment, and FIG. 2 shows a voltage command and a detected current waveform of the inverter.

  In these figures, when starting from the stop state of the PM motor, first, the initial magnetic pole position of the PM motor (position of N pole-S pole in FIG. 1) is first estimated by, for example, the estimation method of Patent Document 1, and then pulsed. Is applied. At this time, the phase of the pulse voltage output from the initial magnetic pole position is set to θ.

  When 90 ° phase θ1 ((1) in the figure) is applied with reference to the initial magnetic pole position, rotational torque is generated and the motor rotates. Next, a pulse voltage is applied to a phase θ2 that is 180 degrees reversed from the phase of θ1. Thus, by outputting the phases θ1 and θ2 that are 180 degrees different from each other in pairs, the same torque is generated in the positive and negative directions, and the rotation opposite to that applied in the above (1) is generated. Next, by applying a pulse voltage to (3) (θ1) in the same phase as (1) and then applying a pulse voltage to (4) (θ2) in the same phase as (2), forward rotation and reverse rotation are performed. Do. By repeating the voltage pulse application of (1) to (4), the motor performs forward / reverse rotation.

  Further, by providing a current stabilization period after each pulse voltage output of (1) to (4), unnecessary vibration is suppressed. Thus, by rotating the motor forward / reversely when starting from the stopped state, the lubricating oil penetrates into the bearing 12 of the PM motor 10 and a layer of lubricating oil is formed on the raceway surface of the bearing 12, so that the starting torque Can be reduced.

  FIG. 2 shows specific waveforms of the voltage command and the detected current output by the inverter so as to perform the forward / reverse rotation, and the current stabilization period T1a from time t0 to time t1 when the motor is stopped. Then, a voltage command of a positive stepped voltage is output, and the staircase has a phase θ1 of 90 degrees ((1) in FIG. 1) with respect to the initial magnetic pole position in the voltage pulse application period T1b from time t1 to time 2. A pulse voltage command larger than the voltage command is output, and a positive constant voltage command is output in a constant voltage output period T1c from time t2 to time t3.

  The output current value rises due to a large positive pulse voltage command output during the voltage pulse application period T1b, and a large torque is generated in the direction of the phase θ1 (1) as shown in the + x part of the constant voltage output period T1c. Then the motor rotates forward. These periods T1a, T1b, and T1c are the positions of θ1 in FIG.

  Next, in the current stabilization period T2a from time t3 to time t4, a stepwise negative voltage command is output, and in the voltage pulse application period T2b from time t4 to time 5, 180 degrees from the phase of θ1. In the inverted phase θ2 ((2) in FIG. 1), a pulse voltage command larger than the stepped voltage command and equivalent to the pulse voltage in the period T1b is output, and a constant voltage output from time t5 to time t6 In the period T2c, a negative constant voltage command is output.

  Due to the large negative pulse voltage command output during the voltage pulse application period T2b, the output current value increases in the negative direction, and the direction of the phase θ2 (2) as shown in the −x portion of the constant voltage output period T2c. A large torque is generated in the motor and the motor rotates in the reverse direction. These periods T2a, T2b, and T2c are the positions of θ2 in FIG.

  After time t6, a pulse voltage is applied to (3) of the same phase (θ1) as (1) by the same operation as the periods T1a, T1b, T1c, and then the same as the periods T2a, T2b, T2c. By the above operation, a pulse voltage is applied to (4) having the same phase (θ2) as that of (2), and the motors are rotated in the forward and reverse directions by repeating (1) to (4).

  As described above, since the current stabilization period is provided after the pulse voltage is output, unnecessary vibration can be suppressed.

  FIG. 3 is a diagram illustrating a pulse voltage command (voltage vector) output by the inverter in the second embodiment of the present invention. In the second embodiment, a pulse voltage is applied as in the first embodiment, and a current stabilization period as shown in FIG. 2 is provided, but the phase of the pulse voltage is output as shown in FIG.

  That is, a pulse voltage is applied to a phase of less than 90 degrees, for example, a phase θ1 of 30 degrees (illustrated (1)) with reference to the initial magnetic pole position (N pole-S pole position in FIG. 3) to generate rotational torque. Thus, the motor is rotated.

  Further, in order to reversely rotate the motor, a voltage equivalent to that of (1) shown in the drawing (1) is applied to (1) by applying a voltage having the opposite phase θ2 (shown (2)) to the initial magnetic pole position. Causes reverse rotation. Next, forward rotation and reverse rotation are performed by applying a pulse voltage to (3) in the same phase as (1) and applying a pulse voltage to (4) in the same phase as (2). At this time, if the angle is less than 90 degrees, the phase is not limited to 30 degrees, and any phase may be used. For this reason, the deviation from the initial magnetic pole position is reduced, and the shock at the time of transition to the acceleration operation can be suppressed.

  Also in the above embodiment, as in FIG. 2, a current stabilization period T1a (T2a), a voltage pulse application period T1b (T2b), and a constant voltage output period T1c (T2c) are provided.

  FIG. 4 is a diagram for explaining a pulse voltage command (voltage vector) output from the inverter in the third embodiment of the present invention. In the third embodiment, a voltage pulse is applied and a current stabilization period as shown in FIG. 2 is provided as in the first and second embodiments, but the phase of the pulse voltage is output as shown in FIG. .

  That is, by applying a pulse voltage to a phase θ1 of less than 90 degrees (60 degrees of (1) in the drawing) with reference to the initial magnetic pole position (position of N pole-S pole in FIG. 4), a rotational torque is generated. Rotate the motor. In addition, in order to reverse the motor, by applying a voltage equivalent to θ1 and opposite phase θ2 (illustrated (2)) and illustrated (1) to the initial magnetic pole position, it is opposite to the case of applying to (1). Cause rotation.

  Next, by applying the pulse voltage to θ3 (30 degrees in the figure (3)) in which the pulse voltage application angle is smaller than θ1 (60 degrees), the rotation is made slightly smaller than in (1). Further, forward rotation / reverse rotation is performed by applying a pulse voltage having an opposite phase θ4 to θ3 and equivalent to (3) in the figure to (4) that is symmetrical to the initial magnetic pole position with (3).

  As described above, the phase of the pulse voltage is determined so that the pulse voltage to be applied gradually approaches the initial magnetic pole position, that is, the number of executions of the control with the forward rotation control and the reverse rotation control as one set is nth ( By setting the phase θ at the time of execution of the (n + 1) th time smaller than the phase θ at the time of execution of (n is a positive number), it is possible to minimize the deviation of the initial magnetic pole position at the time of normal rotation / reverse rotation. Become. For this reason, the shock at the time of changing to an acceleration driving | operation can be suppressed.

  Also in the third embodiment, similarly to FIG. 2, a current stabilization period T1a (T2a), a voltage pulse application period T1b (T2b), and a constant voltage output period T1c (T2c) are provided.

DESCRIPTION OF SYMBOLS 10 ... PM motor 11 ... Shaft 12 ... Bearing T1a, T2a ... Current stabilization period T1b, T2b ... Voltage pulse application period T1bc, T2c ... Constant voltage output period

Claims (3)

A method for starting a permanent magnet synchronous motor in which lubricating oil is used for a motor bearing,
For the armature winding of the permanent magnet synchronous motor in a stopped state,
Forward rotation control for generating forward rotation torque by applying a first pulse voltage of a first phase shifted by a first angle from the initial magnetic pole position;
Reverse rotation control for generating reverse rotation torque by applying a second pulse voltage equivalent to the first pulse voltage in a second phase reversed by the first angle from the initial magnetic pole position;
A permanent magnet type synchronous motor starting method, which is repeatedly executed alternately with a current stabilization period interposed therebetween.   The method for starting a permanent magnet synchronous motor according to claim 1, wherein the first angle is set within 90 degrees.   The number of executions of the control with the forward rotation control and the reverse rotation control as one set is greater than the first angle at the time of execution of the nth time (n is a positive number), the first angle at the time of execution of the (n + 1) th time. The method for starting a permanent magnet synchronous motor according to claim 1 or 2, wherein the starting method is set small.

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