MOTOR CONTROLLER AND MOTOR CONTROL METHOD

Abstract

To provide a motor controller and a motor control method allowing inspection for checking the presence or absence of specification error in motor winding to be conducted more simply, efficiently, and with high accuracy. A voltage command value as a command value for driving control of a motor and an excitation frequency are sampled. An actual current flowing in the motor being driven under control is detected. Theoretical values of a voltage command value, a current, and an excitation frequency are determined from a parameter for driving the motor and a condition at the time of driving. The theoretical values of the voltage command value, the current, and the excitation frequency are compared with the values of the voltage command value, the current, and the excitation frequency respectively at the time of the driving, and it is determined that there is winding abnormality if differences between the comparable values exceed a threshold range set in advance.

Claims

1. A motor controller comprising: a current command calculation unit that calculates a current command for a current to flow in a motor; a current control unit that controls a motor current by changing a voltage command for a voltage to be applied to the motor; an actual current detection unit that detects an actual current flowing in the motor; a storage unit that stores a parameter for driving the motor; and a connection abnormality determination unit that compares a voltage command value, a current value, and an excitation frequency at the time of motor driving with theoretical values of a voltage command value, a current value, and an excitation frequency respectively calculated from the parameter, checks consistency between the characteristics of the driven motor and the parameter for driving the motor, and determines that there is abnormality in motor winding or in connection between the winding and a driving device if a result shows inconsistency therebetween.

2. The motor controller according to claim 1, wherein at least one parameter for driving the motor is an inductance value or a correlated value correlated with an inductance of the motor, and the connection abnormality determination unit compares an actual inductance value of the driven motor obtained from the voltage command value, the current value, and the excitation frequency at the time of the motor driving or a correlated value correlated with an actual inductance with an inductance value calculated from the parameter or a correlated value correlated with an inductance, and checks consistency therebetween.

3. A motor control method comprising: sampling a voltage command value as a command value for driving control of a motor and an excitation frequency; detecting an actual current flowing in the motor being driven under control; determining theoretical values of a voltage command value, a current, and an excitation frequency from a parameter for driving the motor and a condition at the time of driving; and comparing the theoretical values of the voltage command value, the current, and the excitation frequency with the values of the voltage command value, the actual current, and the excitation frequency respectively at the time of the driving, and determining that there is winding abnormality if differences between the comparable values exceed a threshold range set in advance.

4. The motor control method according to claim 3, wherein an inductance value or a correlated value correlated with an inductance is used as the parameter, the method comprising: sampling a voltage command value as a command value for driving control of the motor and an excitation frequency; detecting an actual current flowing in the motor being driven under control; determining an actual inductance value or a correlated value correlated with an actual inductance from the voltage command value, the actual current, and the excitation frequency; and comparing the inductance value as the parameter or the correlated value correlated with the inductance with the actual inductance value or the correlated value correlated with the actual inductance, and determining that there is winding abnormality if a difference between the comparable values exceeds a threshold range set in advance.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG. 1 is a block diagram showing a motor controller according to an embodiment of the present invention;

[0021] FIG. 2 is a flow diagram showing a motor control method according to the embodiment of the present invention;

[0022] FIG. 3 shows an exemplary relationship between the rotation number, voltage, and inductance of a motor; and

[0023] FIG. 4 is a flow diagram showing a motor control method according to the embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0024] A motor controller and a motor control method according to an embodiment of the present invention will be described below by referring to FIGS. 1 to 4.

[0025] The embodiment relates to a motor controller and a motor control method allowing inspection for determining, for example, whether winding specification error (connection error) has occurred in an attached motor more simply and efficiently.

[0026] As shown in FIG. 1, a motor controller A (controller 1 of a motor inspection device A) of the embodiment includes a current command calculation unit 2 that calculates a current command for a current to flow in a motor, a current control unit 3 that controls a motor current by changing a voltage command value for a voltage to be applied to a motor M during driving control of the motor M, and a storage unit 4 that stores a parameter for driving the motor M.

[0027] The motor controller A of the embodiment further includes an actual current detection unit 5 that measures/detects an actual current flowing in the motor M, and a connection abnormality determination unit 6 that compares a voltage command value, a current value, and an excitation frequency at the time of motor driving with theoretical values (design values, required values) of a voltage command value, a current value, and an excitation frequency respectively calculated from a parameter, checks consistency between the characteristics of the driven motor and the parameter for driving the motor M, and determines that there is abnormality in motor winding or in connection between the winding and a driving device if a result shows inconsistency therebetween.

[0028] As shown in FIG. 2, for conducting inspection for checking winding specifications of an attached motor using the motor controller A of the embodiment having the foregoing configuration (according to the motor control method of the embodiment), a voltage command value as a command value for driving control of the motor and an excitation frequency are sampled (extracted) first (Step 1).

[0029] Next, an actual current flowing in the motor being driven under control is measured/detected (Step 2).

[0030] Then, theoretical values of a voltage, a current, and an excitation frequency are calculated from a parameter and a condition at the time of driving (such as a condition for a load on the motor) (Step 3).

[0031] Then, the theoretical values of the voltage, the current, and the excitation frequency are compared with the values of the voltage command value, the current, and the excitation frequency (command value) respectively at the time of driving (Step 4). If ranges of differences between the comparable values exceed a threshold range set in advance, in other words, if differences of the theoretical values of the voltage command value, the current, and the excitation frequency from the values of the voltage command value, the current, and the excitation frequency (command value) respectively at the time of the driving exceed an allowable error range, it is determined that there is winding abnormality in the motor. If the differences are within the threshold range, the winding is determined to be proper (Step 5). In this step, if a difference of any of the values from a corresponding theoretical value exceeds the allowable error, it is determined that there is winding abnormality.

[0032] A voltage command value, an actual current, an excitation frequency, and an actual inductance value are related to each other expressed in FIG. 3 and by the following formula (1):

[00001]$\begin{array}{cc}\mathrm{ACTUAL}.Math..Math.\mathrm{INDUCTANCE}.Math..Math.\mathrm{VALUE}\frac{\mathrm{VOLTAGE}.Math..Math.\mathrm{COMMAND}.Math..Math.\mathrm{VALUE}}{\begin{array}{c}\mathrm{ACTUAL}.Math..Math.\mathrm{CURRENT}\\ \mathrm{EXCITATION}.Math..Math.\mathrm{FREQUENCY}\end{array}}& \left[\mathrm{Math}..Math.1\right]\end{array}$

[0033] Thus, this actual inductance value is usable as the foregoing parameter. Further, an item correlated with an inductance can be handled as a parameter. If the motor is a synchronous motor, for example, a rotation number can be used as a parameter. Specifically, the motor according to the present invention can either be a synchronous motor or an induction motor.

[0034] As shown in FIG. 4, if the actual inductance value is used, a voltage command value and an excitation frequency during control of the motor are sampled (Step 1). Then, an actual current flowing in the motor is measured/detected (Step 2).

[0035] Next, an actual inductance value is determined from the voltage command value, the actual current, and the excitation frequency and using FIG. 3 and the formula (1) (Step 3).

[0036] Then, an inductance value as a parameter and the actual inductance value are compared (Step 4). If a range of a difference therebetween exceeds a threshold range set in advance, it is determined that there is winding abnormality. If the difference is within the threshold range, the winding is determined to be proper (Step 5).

[0037] As described above, according to the motor controller A and the motor control method of the embodiment, a voltage command value, a current value, and an excitation frequency at the time of motor driving are compared with theoretical values of a voltage command value, a current value, and an excitation frequency respectively calculated from a parameter for driving a motor. Then, differences between the comparable values are checked to determine the presence or absence of a difference exceeding the allowable error set in advance, namely, to determine consistency. By doing so, specification error in motor winding (connection error) can be detected.

[0038] Thus, according to the motor controller A and the motor control method of the embodiment, compared to the conventional inspection conducted by actually measuring a voltage value, etc., failure or no-failure can be judged by determining the characteristics of a motor on the basis of a voltage command value output during control of a current in the motor. This makes it possible to inspect winding specifications of the motor more simply and efficiently.

[0039] As shown in FIG. 3, an inductance value changes with change in the rotation number of a motor or a voltage at the motor. Thus, by using this inductance value as a parameter and changing a voltage command value, winding specifications of the motor can be inspected easily under multiple conditions. This achieves implementation of inspection simply and efficiently even under multiple conditions. As a result, it becomes possible to conduct the inspection with high reliability and high accuracy.

[0040] While an embodiment of the motor controller and the motor control method according to the present invention has been described above, the present invention should not be limited to the foregoing embodiment but can be changed appropriately within a range not deviating from the substance of the invention.

EXPLANATION OF REFERENCE NUMERALS

[0041] 1 Controller [0042] 2 Current command calculation unit [0043] 3 Current control unit [0044] 4 Storage unit [0045] 5 Actual current detection unit [0046] 6 Connection abnormality determination unit [0047] A Motor controller [0048] M Motor