JP2007116759A - Method for detecting magnetic pole of synchronous motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for detecting the magnetic pole of a synchronous motor with high precision in a short time. <P>SOLUTION: The magnetic pole detection method of a synchronous motor 1 for determining an applying current phase based on a start position, i.e. a temporary magnetic pole position, without using a CS signal comprises step 1 for initially storing the relation between the absolute positional information of an absolute scale obtained through estimation of magnetic pole position and the current phase in a storage device 4, and step 2 for driving the synchronous motor 1 by deriving the current phase conversely from the relation between the initially stored absolute positional information of the absolute scale and the current phase based on the absolute positional information of the absolute scale from next power up. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vector control method for a synchronous motor, and more particularly to a magnetic pole detection method at start-up.

  Conventionally, vector control of a synchronous motor detects the magnetic pole position by an absolute position detector (resolver or absolute encoder), and performs electromagnetic force control while controlling the amplitude and phase of a sine wave current having a phase synchronized with the magnetic pole position. Is.

  Basically, the current phase γmax at which the generated torque is maximum is obtained by shifting the current phase γmin at which the generated electromagnetic force becomes zero regardless of the applied current by 90 °. As a method of obtaining the current phase, there is a method of updating the current phase γ according to the polarity of the generated torque (see, for example, Patent Document 1).

This method changes the current phase γ, determines the current phase γmin where the generated electromagnetic force becomes zero regardless of the magnitude of the applied current, based on the polarity of acceleration, and detects it with the current phase γmin and the position detector Using the provisional magnetic pole position δ, a current phase correction amount γmax that maximizes the generated electromagnetic force is determined.
JP 2003-88164 A

  However, in the above-described technique, it is necessary to apply a current every time the power is turned on to perform magnetic pole position estimation. To increase the estimation accuracy of the current phase, a long estimation time is required, and the estimation time is shortened. There was a problem that the estimation accuracy was lowered.

  In addition, there is a problem that the current phase error obtained by the magnetic pole position estimation varies for each magnetic pole position estimation.

  The present invention solves the above-described conventional problems. Once the magnetic pole position is estimated, the current phase is derived in a short time without applying current from the next power-on, and the current phase error at each detection. It is an object of the present invention to provide a magnetic pole detection method without any problem.

  In the synchronous motor magnetic pole detection method that determines the applied current phase based on the temporary magnetic pole position that is the starting position, the absolute scale absolute position after the magnetic pole position estimation and the current phase at that position are the current phase at the absolute scale absolute position. Alternatively, the absolute scale absolute position at a certain current phase is saved in a storage device, and the absolute scale absolute position at power-on is determined from the relationship between the absolute scale absolute position saved in the storage device and the current phase when the power is turned on next time. This is a magnetic pole detection method for deriving the current phase at.

  According to the magnetic pole detection method of the synchronous motor of the present invention, once the magnetic pole position is estimated, the magnetic pole can be detected in a short time without the need to apply current from the next power-on, and the current at each magnetic pole detection. Variations in phase error can be eliminated.

A position detector that detects the absolute position of the synchronous motor, a magnetic pole detector that detects the current phase, a current controller that controls the winding current of the synchronous motor by an output command of the magnetic pole detector, and a detected current phase And a storage device that stores the relationship between the absolute scale absolute position of the synchronous motor and the relationship between the current phase obtained by the magnetic pole position estimation and the absolute scale absolute position of the synchronous motor is stored in the storage device when the power is turned on next time. Is a magnetic pole detection method in which the current phase at the absolute position of the synchronous motor absolute scale when the power is turned on is derived by calculation from the relationship between the stored current phase and the absolute position of the absolute scale of the synchronous motor.

  Embodiment 1 of the present invention will be described below with reference to the drawings.

FIG. 1 is a flowchart of detection processing by a magnetic pole detection method for a synchronous motor according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a circuit configuration of a driving device based on vector control of the synchronous motor 1 (three phases) to which the synchronous motor magnetic pole detection method is applied. A position detector 2 in the figure detects the rotational position of the synchronous motor. The magnetic pole position estimator 3 estimates the relationship between the current phase of the synchronous motor and the absolute scale absolute position using, for example, magnetic pole position estimation according to the method of Patent Document 1, and stores the relationship in the storage device 4. The magnetic pole detector 5 calculates from the position information of the synchronous motor 1 detected by the position detector 2, the current phase of the synchronous motor stored in the storage device 4, and the absolute scale absolute positional relationship, and generates a torque command and a phase command. Is output. The current controller 6 calculates three-phase current commands iu, iv, and iw from the input torque command and phase command, and supplies these three-phase current commands to the synchronous motor 1 to drive the synchronous motor 1.
FIG. 3 is a diagram showing the relationship between the current phase of the synchronous motor and the absolute scale absolute position relationship shown in FIG. In the figure, P1 and A1 represent the absolute scale absolute position and current phase of the synchronous motor at the end of the magnetic pole position estimation. P2 and A2 in the figure represent the absolute scale absolute position and current phase of the synchronous motor when the power is turned on again. In the figure, Amax represents the maximum value of the current phase. In the figure, Q represents the absolute scale length corresponding to one cycle of the current phase.

  Next, the magnetic pole detection method in the present embodiment will be described with reference to the flowchart of FIG.

  In process 11, it is determined whether or not the magnetic pole position is to be estimated. If the magnetic pole position is estimated, the process proceeds to step 12. If the magnetic pole position is not estimated, the process proceeds to step 21.

  In process 12, the current phase is estimated using the magnetic pole position estimation. Proceed to step 13.

In the process 13, the relationship between the current phase of the synchronous motor 1 after the magnetic pole position estimation and the absolute scale absolute position is stored in the storage device 4. By storing either the absolute position of the absolute scale at the current phase serving as the reference of the synchronous motor 1 or the current phase of the synchronous motor 1 at the absolute position serving as the reference, the amount of information stored in the storage device 4 can be reduced. Less. The synchronous motor is driven using the current phase obtained by the magnetic pole position estimation. (End of magnetic pole detection)
In the process 21, the position information is obtained from the position detector 2, and the relationship between the current phase of the synchronous motor 1 and the absolute scale absolute position is obtained from the storage device 4. Proceed to processing 22.

In process 22, the current phase at the position obtained from the position detector 2 is derived. When the absolute scale absolute position stored in the storage device is P1, the current phase of the synchronous motor is A1, and the absolute scale absolute position when the power is turned on again is P2, the current phase A2 at the absolute scale absolute position P2 is the current phase. It can be derived from Equation 1 using an absolute scale length Q corresponding to the maximum value Amax and one cycle of the current phase.

  Here, since A2 has the constraint condition of Expression 2, the coefficient n is adjusted to satisfy Expression 2.

The synchronous motor is driven using the derived current phase. (End of magnetic pole detection)
FIG. 3 shows the relationship between the current phase of the synchronous motor and the absolute position of the absolute scale.

  The magnetic pole detection method for a synchronous motor according to the present invention can detect magnetic poles in a short time and with high accuracy by replacing torque with a thrust as well as a rotary synchronous motor, and the magnetic poles of a direct acting synchronous motor (linear motor). It is also useful for detection.

Flowchart of magnetic pole detection in Embodiment 1 of the present invention The block diagram of the vector control circuit of the synchronous motor in Example 1 of this invention FIG. 2 is a diagram showing the relationship between the current phase of the synchronous motor and the absolute scale absolute position in the first embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Synchronous motor 2 Position detector 3 Magnetic pole position estimator 4 Memory | storage device 5 Magnetic pole detector 6 Current controller

Claims (3)

In the magnetic pole detection method of a synchronous motor that determines the current phase to be applied based on the temporary magnetic pole position that is the starting position without using the CS signal, the relationship between the absolute scale absolute position information obtained by the magnetic pole position estimation and the current phase The current phase is derived from the relationship between the absolute position information of the absolute scale and the current phase that has been initially stored, based on the absolute position information of the absolute scale that has been stored from the first time when the power is turned on. And step 2 for driving the synchronous motor. The magnetic pole detection method according to claim 1, wherein in step 1, the current phase at a certain absolute position of the absolute scale or the absolute position of the absolute scale at a certain current phase is stored in a storage device. The magnetic pole detection method according to claim 1, wherein in step 2, the current phase is derived by calculation on the contrary from the relationship between the absolute position information of the absolute scale that has been initially stored and the current phase.