JP2010124610A - Method of controlling pm motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the error in the estimation of a rotor temperature in the control of a PM motor and to alleviate a data processing burden of a computer. <P>SOLUTION: In the method of controlling the PM motor 12, the rotation speed, induced voltage and stator temperature of the PM motor 12 are measured, and the rotor temperature of the PM motor 12 is estimated with an arithmetic comparing unit 5 from the induced voltage, rotation speed and stator temperature to limit the current command value output to the current controlling block of the PM motor 12 with a limiter 4 based on the estimated rotor temperature. The induced voltage, rotation speed and stator temperature are measured at a preliminary operation, and the constant of the rotor temperature is calculated from the measured value for storage in a storage unit. The induced voltage, rotation speed and stator temperature are measured during the operation, and the rotor temperature is estimated from the two data of them and the constant of the rotor temperature to limit the current command value based on the rotor temperature. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a PM motor control method.

  Generally, in a PM motor (permanent magnet type synchronous motor), heat is generated when a current flows through a winding of a stator, and the temperature of the rotor (magnet) rises when the heat is transmitted to the magnet of the rotor. Are known. As described above, when the temperature of the winding or the magnet rises, the winding is burned or the magnetic flux is reduced due to the demagnetization phenomenon of the magnet.

  Here, a general PM motor will be described based on a torque characteristic example of the PM motor. FIG. 3 is a graph showing an example of dynamic characteristics (relationship between rotational speed and torque) of the PM motor when the rotor (magnet) is at a high temperature and at a normal temperature. For example, the solid line A in FIG. 3 shows the dynamic characteristics of the rotor (magnet) at normal temperature, and the dotted line B in FIG. 3 shows the dynamic characteristics of the rotor at high temperature. As shown in the figure, when the rotor temperature is high, the dynamic characteristics change due to the demagnetizing action (the torque decreases even at the same rotational speed).

  For this reason, it is necessary to monitor the temperature of the stator (winding) and rotor (magnet), but in recent motor control technology, only the temperature of the stator (winding) is detected from the viewpoint of miniaturization of the PM motor. (For example, detection is performed by a thermistor or the like). However, since the actual rotor temperature cannot be accurately grasped, the rotor temperature may be high even if the stator temperature is low, and as a result, the dynamic characteristics change (torque decreases) due to the demagnetization action. . Further, if the rotor temperature at the time of measuring the dynamic characteristics varies from product to product, the dynamic characteristics between products vary.

  In order to solve the above problems, several methods for estimating the temperature of the rotor without using a temperature sensor have been proposed (for example, Patent Documents 1 and 2).

In Patent Document 1, it is proposed to estimate the magnet temperature by a characteristic equation from the relationship between the induced voltage of the motor, the motor rotation speed, and the magnetic flux density of the permanent magnet. Japanese Patent Application Laid-Open No. 2004-228561 proposes that the relationship between the induced voltage of the motor, the motor rotation speed, and the magnet temperature coefficient is obtained in advance by experiments and provided as a map to estimate the rotor temperature and the magnet temperature.
JP 2007-6613 (Claim 2, Claim 6, [0036]) JP 2007-104855 A (paragraphs [0051] to [0053], FIGS. 3 and 4)

  However, in the case of Patent Document 1, the magnet temperature is estimated from the induced voltage, the motor rotational speed, and the magnetic flux density of the permanent magnet in the characteristic formula. However, since the temperature coefficient of the catalog value is used for the magnetic flux density, An error is included in the magnetic flux density change with respect to the temperature change, and accurate temperature estimation is difficult.

  In Patent Document 2, since the induced voltage, motor rotation speed, and magnet temperature coefficient are obtained by preliminary operation (trial operation), accurate temperature estimation can be performed as compared with Patent Document 1. However, since data having three parameters, that is, induced voltage, motor rotation speed, and magnet temperature coefficient, is mapped, the data processing burden on a computer (a CPU or the like that can compare operations) for motor control increases. In addition to being unsuitable for high-speed processing, it is necessary to use an expensive computer for high-speed processing, which is not easy to use.

  As described above, in controlling the PM motor, it is required to suppress the error in estimating the rotor temperature and reduce the data processing burden on the CPU.

  According to a first aspect of the present invention, there is provided a PM motor control method in which a PM motor is driven by a three-phase alternating current output from an inverter unit, and an induced voltage, a rotational speed, and a stator temperature of the PM motor are respectively measured by voltage sensors, A magnetic pole position sensor and a temperature sensor are used to measure the PM motor rotor temperature from the induced voltage, rotational speed, and stator temperature, and the PM motor current control block is estimated based on the estimated rotor temperature. A control method for a PM motor that limits an output current command value in a limiter, and measures the induced voltage, rotation speed, and stator temperature during preliminary operation, and from the measured values, A constant α determined by the induced voltage difference and the stator temperature difference is calculated by the following characteristic equation (1) and stored in the storage unit. In addition, a table sheet of induced voltage-rotational speed characteristics using the stator temperature as a parameter from the measured value is created and stored in the storage unit, and a threshold value of the rotor temperature is set in the calculation comparison unit. Rotation speed and stator temperature are measured, and if either the induced voltage or the stator temperature cannot be measured, a value that cannot be measured by the table sheet is obtained and stored in the induced voltage, the stator temperature, and the storage unit From the calculated constant α, the rotor temperature is calculated by the following characteristic equation (2). When the rotor temperature during operation is higher than the threshold, a temperature compensation command is output from the calculation comparison unit to the limiter, and the current is output from the limiter. The command value is limited.

Constant α = stator temperature difference / induced voltage difference (1)
Stator temperature difference; stator temperature difference between stator temperature A and stator temperature B measured at the same rotational speed Induced voltage difference; induced voltage difference between stator temperature A and stator temperature B measured at the same rotational speed Rotor temperature Tr = stator Temperature + induced voltage x α (2)
According to a second aspect of the present invention, there is provided a PM motor control method in which a PM motor is driven by a three-phase alternating current output from an inverter unit, and an induced voltage, a rotational speed, and a stator temperature of the PM motor are respectively measured with a voltage sensor and a magnetic pole. The measurement is performed by a position sensor and a temperature sensor, and the rotor temperature of the PM motor is estimated by the calculation comparison unit from the induced voltage, the rotation speed, and the stator temperature, and output to the current control block of the PM motor based on the estimated rotor temperature. A control method for a PM motor that limits a current command value to be generated in a limiter, and measures the induced voltage, the rotational speed, and the stator temperature during preliminary operation. The constant β determined by the rotation speed and corresponding to the rotor temperature is calculated by the following characteristic equation (3) and stored in the storage unit. In addition, a table sheet of induced voltage-rotation speed characteristics using the stator temperature as a parameter from the measured value is created and stored in the storage unit, and a constant β at the rotor temperature threshold value is set in the calculation comparison unit. In addition to measuring the induced voltage, rotation speed, and stator temperature, if either the induced voltage or the rotation speed could not be measured, obtain a value that could not be measured by the table sheet, from the induced voltage, the rotation speed. The constant γ is calculated by the following characteristic equation (3 ′), the constant β at the threshold stored in the storage unit in advance during preliminary operation is compared with the constant γ during operation, and if the constant γ is smaller, the operation comparison unit The temperature compensation command is output from the limiter to the limiter, and the current command value is limited by the limiter.

Constant β = induced voltage difference / rotational speed difference (3)
Induced voltage difference; difference in induced voltage between rotational speed A and rotational speed B measured at the same stator temperature Rotational speed difference; rotational speed difference between rotational speed A and rotational speed B measured at the same stator temperature Constant γ = induced Voltage / Rotation speed (3 ')
According to a third aspect of the present invention, there is provided a PM motor control method according to the second aspect of the invention, wherein the constant β and the constant γ calculated by the equations (3) and (3 ′) are corrected and the current command value after correction is appropriate. The value of the constant β ′ and the constant γ ′ is calculated by dividing by the constant β of the reference stator temperature selected so as to be a value, and the constant at the constant γ calculated by the equation (3 ′) during operation is calculated. γ ′ is compared with the value of constant β ′ at the threshold rotor temperature. If the constant γ ′ is smaller, the limiter calculates and outputs a corrected current command value by the following characteristic equation (4). The current command value is limited.

  Current command value after correction = current command value × γ ′ (4)

  As described above, according to the first to third aspects of the invention, the rotor temperature of the PM motor is estimated based on the data measured from the actual machine, so that variation in dynamic characteristics between products can be suppressed, It is possible to improve the accuracy of the estimated rotor temperature. Further, as described above, since the rotor temperature is estimated based on a constant, the burden of data processing by a computer for performing motor control is reduced, and high-speed processing by an inexpensive computer is also possible.

  According to the second aspect of the present invention, since the constant γ calculated during the operation is only compared with the threshold constant β stored during the preliminary operation, a computer for performing motor control is used. The burden of data processing is further reduced, and high-speed processing is possible even with an inexpensive computer.

  According to the third aspect of the present invention, the corrected current command value can be easily calculated in the limiter.

<Embodiment 1>
The first embodiment will be described below with reference to the drawings. FIG. 1 shows a current control block diagram of a PM motor (permanent magnet synchronous motor) according to the first embodiment. Id ^* and Iq ^* are a command value for the d-axis current and a command value for the q-axis current that are input to the current control block, and are input to the subtraction units 1 and 2 respectively. The output d-axis current detection value Id ^ and q-axis current detection value Iq ^ are subtracted, respectively. The output signals (Id ^* −Id ^) and (Iq ^* −Iq ^) of the subtracting units 1 and 2 are the temperature compensation command output from the operation comparing unit 5 and the motor rotation output from the speed calculating unit 6 in the limiter 4. Limitation is applied according to the speed, and the current is output to the current control units 7 and 8, respectively. (The operation of the limiter 4 and the like will be described later). The current control units 7 and 8 perform PI calculation on the output signal from the limiter 4 and output it as d-axis and q-axis voltage command values. The d-axis and q-axis voltage command values are input to the rotation-fixed voltage coordinate conversion unit 9, coordinate-converted from the rotation coordinate system to the fixed coordinate system, and output to the 2-phase / 3-phase conversion unit 10. Next, in the two-phase / three-phase converter 10, the voltage command value in the fixed coordinate system is converted into the U-phase voltage command Vu, the V-phase voltage command Vv, and the W-phase voltage command Vw, and the switching element constituting the inverter unit 11. It is output to the gate terminal of the IGBT. The inverter unit 11 is controlled based on a three-phase voltage command (U-phase voltage command Vu, V-phase voltage command Vv, W-phase voltage command Vw), and outputs a three-phase alternating current to the PM motor 12 to thereby generate a PM motor. 12 is driven and controlled.

  The three-phase alternating current that drives the PM motor 12 is A / D converted from an analog signal to a digital signal in the A / D converter 13 and output as digital three-phase alternating current values Iu, Iv, and Iw. The three-phase / two-phase conversion unit 14 converts the detected current value into a fixed coordinate system. The detected current value of the fixed coordinate system is output to the fixed-rotating current coordinate conversion unit 3, and the fixed-rotating current coordinate conversion unit 3 detects the d-axis current detection value Id ^ and the q-axis current detection value Iq ^ of the rotating coordinate system. Is then input to the subtracting units 1 and 2.

  On the other hand, the induced voltage of the PM motor 12 is detected by a voltage sensor (not shown) and input to the operation comparison unit 5 after A / D conversion (from an analog signal to a digital signal) by the A / D conversion unit 15. 5, a temperature compensation command is input to the limiter 4. The phase θ (magnetic pole position) of the PM motor 12 is detected by a magnetic pole position sensor (PS) 16, and a signal indicating this phase θ is A / D converted from an analog signal to a digital signal by an A / D converter 17. Is output to the speed calculator 6. In the speed calculation unit 6, the rotational speed of the PM motor 12 is calculated based on the digital signal indicating the phase θ and input to the limiter 4. The digital signal indicating the phase θ is also input to the fixed-rotating current coordinate conversion unit 3 and the rotation-fixed voltage coordinate conversion unit 9, and is synchronized with the induced voltage.

  Hereinafter, a method for estimating the rotor temperature of the PM motor 12 and a current control method in the first embodiment will be specifically described. Procedures [1] to [6] show the procedure during preliminary operation, and procedures [7] to [9] show the procedure during operation.

[During preliminary operation]
[1] First, a stator temperature is measured by a temperature sensor (for example, thermistor; not shown) at a certain rotational speed, and the PM motor 12 is detected by the magnetic pole position sensor 16 when the stator temperature is normal temperature (for example, 25 ° C.). , And the gate of the inverter unit 11 is turned off, and the induced voltage of the PM motor 12 (induced voltage when the gate is turned off) is measured by the voltage sensor.

  [2] The PM motor 12 is driven at the same rotational speed as in the procedure [1] for a certain time (for example, several hours) to increase the stator temperature, and the induced voltage at each stator temperature (for example, 80 ° C.) is measured.

  [3] The stator temperature, rotational speed, and induced voltage measured in steps [1] and [2] are output to a storage unit (for example, a storage unit configured by an IC or the like; not shown), and the stator temperature is used as a parameter. Is stored as a table sheet having the "induced voltage-rotation speed" characteristic.

  That is, the permanent magnet magnetic flux density of the rotor of the PM motor 12 decreases as the temperature increases. Therefore, as shown in FIG. 2 (a graph showing an example of the induced voltage-rotational speed characteristic), when the rotor temperature increases, the induced voltage decreases even at the same rotational speed.

  [4] The induced voltage and the stator temperature stored in the storage unit in step [3] (measured in step [1] and step [2]) are output to the operation comparison unit 5, and the stator temperature difference and induced voltage difference are output. Is calculated by the following equation (1). In addition, the stator temperature difference of the following formula (1) indicates the difference (° C.) between the stator temperature measured in the procedure [1] and the temperature measured in the procedure [2], and the induced voltage difference is measured in the procedure [1]. The difference [V] between the induced voltage measured and the induced voltage measured in the procedure [2] is shown. The constant α is output from the calculation comparison unit 5 and stored in the storage unit.

Constant α (° C./V)=Stator temperature difference (° C.) / Induced voltage difference (V) (1)
[5] The rotation speed of the PM motor 12 is changed, and the procedures [1] to [ 4 ] are repeatedly executed to complete the table sheet of the storage unit.

  [6] A threshold value of the rotor temperature Tr (° C.) is set in the calculation comparison unit 5.

[During operation]
[7] When the state from the inverter 11 to the PM motor 12 is not energized (when idling when the inverter 11 is off and when not energizing when the inverter is operating), the stator temperature, induced voltage, and rotational speed are measured.

  [8] The rotor temperature is calculated by the following equation (2) from the stator temperature measured in step [7], the induced voltage, and the constant α stored during the preliminary operation.

  When one of the stator temperature and the induced voltage is not known, the stator temperature or the induced voltage is calculated from the data of the table sheet based on the rotation speed, and the following equation (2) is calculated based on the value.

Rotor temperature Tr (° C.) = Stator temperature Ts (° C.) + Induced voltage (V) × α (° C./V) (2)
[9] The operation comparison unit 5 compares the rotor temperature Tr (° C.) estimated in the procedure [8] with the rotor temperature threshold value set in the procedure [6]. As a result of the comparison, if it is determined that the rotor temperature Tr (° C.) estimated in step [8] is higher, a temperature compensation command is output from the operation comparison unit 5 to the limiter 4, and the limiter 4 performs subtraction. restriction is applied on the signal output from the parts 1,2 ((Id ^* -Id ^) signal and (Iq ^* -Iq ^) signal). By being restricted as described above, the current value applied to the stator (winding) of the PM motor 12 is reduced (or stopped), the stator temperature is lowered, and accordingly the rotor temperature Tr (° C.). Also decreases. As a result of the comparison, when it is determined that the rotor temperature estimated in the procedure [8] is lower, the limiter 4 does not limit.

  In the first embodiment, since the rotor temperature Tr (° C.) is estimated from data (stator temperature, rotation speed, induced voltage) measured from the actual machine, it is possible to suppress variations in dynamic characteristics between products. The accuracy of the estimated rotor temperature Tr (° C.) can be improved.

  Further, as described above, since the estimation of the rotor temperature Tr (° C.) is performed based on the constant α, the rotor temperature is estimated in consideration of data of three (induced voltage, stator temperature, constant α). In addition, the data processing load by a computer (a CPU or the like that can compare operations) for motor control is reduced, and high-speed processing by an inexpensive computer is also possible.

  Further, when the rotor temperature Tr (° C.) is equal to or higher than the threshold value, the limiter 4 performs a restriction on the d-axis current command value and the q-axis current command value, so that an increase in the rotor temperature Tr (° C.) can be suppressed. It is possible to suppress the change in the dynamic characteristics due to the change in the rotor temperature Tr (° C.).

<Embodiment 2>
The current control block of the PM motor 12 in the second embodiment is configured in the same manner as in FIG. 1, and its operation is basically the same.

  Hereinafter, a method for estimating the rotor temperature and the current control method for the PM motor 12 according to the second embodiment will be specifically described. In addition, procedure [1]-procedure [7] show the procedure at the time of preliminary operation, and procedure [8]-procedure [11] show the procedure at the time of operation.

[During preliminary operation]
[1] First, the stator temperature is measured at a certain rotational speed, and when the stator temperature is normal temperature (for example, at 25 ° C.), the rotational speed of the PM motor 12 is detected by the magnetic pole position sensor 16 and the inverter unit 11 The gate is turned off and the induced voltage of the PM motor 12 is measured by the voltage sensor.

  [2] The PM motor 12 is driven at the same rotational speed as in the procedure [1] for a certain time (for example, several hours) to increase the stator temperature, and the induced voltage at each stator temperature (for example, 80 ° C.) is measured.

  [3] The stator temperature, rotational speed, and induced voltage measured in the steps [1] and [2] are output to the storage unit and stored as a table sheet of “induced voltage-rotational speed” characteristics using the stator temperature as a parameter. The

  [4] The rotation speed of the PM motor 12 is changed, and the procedures [1] to [3] are repeatedly executed.

  [5] A constant β determined by the induced voltage and the rotation speed is calculated from the data of the table sheet stored in the storage unit by the procedures [3] and [4] by the following equation (3). This constant β corresponds to the slope β of the characteristics (for example, characteristics C and D) in FIG. 2 (characteristic chart of induced voltage and rotational speed at each stator temperature). The induced voltage difference in the following equation (3) indicates the induced voltage difference between the rotational speed A and the rotational speed B at the same stator temperature, and the rotational speed difference is the rotational speed between the rotational speed A and the rotational speed B at the same stator temperature. Indicates the difference.

Constant β = induced voltage difference [V] / rotational speed difference [rpm] (3)
The constant β calculated by the above equation (3) corresponds to the rotor temperature Tr (° C.). When the rotor temperature is low, the constant β is a large value, and when the rotor temperature is high, the constant β is a small value. Therefore, the rotor temperature can be estimated from the value of the constant β.

  [6] The operation comparison unit 5 converts the constant β of the reference stator temperature (for example, 25 ° C.) out of the constant β calculated in the procedure [5] into a constant β ′ = 1. Further, the value of the constant β at other stator temperatures is divided by the value of the constant β of the reference stator temperature to calculate the value of the constant β ′ at each stator temperature. That is, the value of the constant β of the reference stator temperature is set to β ′ = 1, and the value of the constant β at each other stator temperature is converted according to the constant β of the reference stator temperature (the reference stator The temperature will be described later). Note that the value of the constant β and the value of the constant β ′ at each stator temperature are output and stored in the storage unit.

  [7] The operation comparison unit 5 sets a threshold value of the rotor temperature, and outputs the value of the constant β ′ at this threshold value to the storage unit for storage. Examples of a method for calculating the constant β ′ at the threshold include a method in which the operation comparison unit 5 divides the constant β at the reference stator temperature from the constant β at the threshold.

[During operation]
[8] The stator temperature and the induced voltage are measured when the state from the inverter 11 to the PM motor 12 is not energized (when idling when the inverter 11 is off and when deenergizing during inverter operation).

  [9] In the operation comparison unit 5, the constant γ is calculated by the following equation (3 ′) from the induced voltage and the rotational speed measured in the procedure [8].

Constant γ = induced voltage [V] / rotational speed [rpm] (3 ′)
The constant γ corresponds to the slope of the characteristic in FIG. When one of the induced voltage and the rotational speed is unknown, the induced voltage or the rotational speed is calculated from the data of the table sheet based on the stator temperature, and the calculation of equation (3 ′) is performed based on the calculated value.

  [10] The value of the constant γ ′ is calculated from the value of the constant γ calculated by the above equation (3 ′). Examples of a method for calculating the constant γ ′ include a method in which the constant γ calculated by the above equation (3 ′) is calculated by dividing the constant γ ′ by the constant β of the stator temperature serving as a reference in the calculation comparison unit 5.

[11] In the operation comparison unit 5, the value of the constant γ ′ calculated in step [10] and the value of the constant β ′ in the threshold set in [7] (for example, the constant β ′ = 0.4) are obtained. To be compared. When it is determined that the value of the constant γ ′ calculated in the procedure [10] is equal to or less than the value (0.4) of the constant β ′ in the threshold, the constant γ calculated in the procedure [10] as a temperature compensation command to the limiter 4. The value of ′ is output, and the signals (d-axis current command value (Id ^* −Id ^), q-axis current command value (Iq ^* −Iq ^)) output from the subtracting units 1 and 2 are limited.

  In the limiter 4, as shown in the following equations (4) and (5), the signals output from the subtracting units 1 and 2 are multiplied by the value of the constant γ ′ calculated in the procedure [10], A corrected d-axis current command Id and a corrected q-axis current command Iq are calculated.

Id = (Id ^* −Id ^) × γ ′ (4)
Iq = (Iq ^* −Iq ^) × γ ′ (5)
For example, when the constant γ ′ calculated in the procedure [10] is 0.4, the corrected d-axis current command value Id and the corrected q-axis current command value Iq are expressed by the following equations (6) and (7).

Id = (Id ^* −Id ^) × 0.4 (6)
Iq = (Iq ^* −Iq ^) × 0.4 (7)
As described above, the signals output from the subtracting units 1 and 2 are limited, so that the current value applied to the stator (winding) of the PM motor 12 is reduced and the stator temperature is lowered. Tr (° C.) also decreases.

  Since the corrected (d-axis, q-axis) current command value is determined in the above characteristic formulas (4), (5), or (6), (7), the reference stator used when calculating the constant γ ′ It is necessary to select an appropriate value for the temperature. That is, since the reference stator temperature varies depending on the PM motor winding, rotor, and the like, the reference in step [6] is set so that the corrected (d-axis, q-axis) current command value becomes an appropriate value. The stator temperature is appropriately selected.

  When the value of the constant γ ′ calculated in the procedure [10] is determined to be equal to or larger than the threshold value β ′ (for example, the constant β ′ = 0.4) set in [7], the limiter 4 limits the value. Is not done.

  In the second embodiment, since data obtained from an actual machine is used, variation in dynamic characteristics between products can be suppressed, and accuracy of the estimated rotor temperature Tr (° C.) can be improved. It becomes possible.

  Further, during operation, only the constant γ ′ calculated by the operation comparison unit 5 is compared with the threshold constant β ′ stored in advance in the table sheet. The burden of data processing due to operations such as CPUs can be reduced, and high-speed processing is possible even with an inexpensive computer. Furthermore, when the corrected current command value is calculated from the current command value, the current command value is simply multiplied by a constant γ ′, so that the corrected current command value can be easily calculated.

  Further, when the value of the constant γ ′ becomes equal to or smaller than the threshold value, the limiter 4 limits the d-axis current and the q-axis current, and can suppress the increase in the rotor temperature and suppress the change in the dynamic characteristics due to the temperature. be able to.

  Although the present invention has been described in detail only for the specific examples described above, it is obvious to those skilled in the art that various changes and modifications are possible within the scope of the technical idea of the present invention. Such variations and modifications are naturally within the scope of the claims.

  For example, in the first and second embodiments, the current control block having a specific configuration has been described. However, the current control block having other configurations can be appropriately applied.

It is a current control block diagram of PM motor by Embodiment 1 and Embodiment 2 of this invention. It is a characteristic view which shows the relationship between the rotational speed and induced voltage of PM motor by Embodiment 1 and Embodiment 2 of this invention. It is a characteristic view which shows the relationship between the rotational speed and torque of a general PM motor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 ... Fixed-rotation current coordinate conversion part 4 ... Limiter 5 ... Calculation comparison part 6 ... Speed calculation part 7, 8 ... Current control part 9 ... Rotation-fixed voltage coordinate conversion part 10 ... Two-phase / 3-phase conversion part 11 ... Inverter Part 12: PM motor 13, 15, 17 ... A / D converter 14 ... Three-phase / 2-phase converter 16 ... Magnetic pole position sensor

Claims (3)

The PM motor is driven by the three-phase alternating current output from the inverter unit, and the induced voltage, rotational speed, and stator temperature of the PM motor are measured by a voltage sensor, a magnetic pole position sensor, and a temperature sensor, respectively, and the induced voltage, Control of the PM motor that estimates the rotor temperature of the PM motor from the rotation speed and the stator temperature in the calculation comparison unit, and limits the current command value output to the current control block of the PM motor based on the estimated rotor temperature in the limiter. A method,
During the preliminary operation, the induced voltage, the rotational speed, and the stator temperature are measured, and a constant α determined by the induced voltage difference and the stator temperature difference is calculated from the measured values by the following characteristic equation (1). And storing it in the storage unit, creating a table sheet of induced voltage-rotation speed characteristics using the stator temperature as a parameter from the measured value and storing it in the storage unit, and setting the threshold value of the rotor temperature in the calculation comparison unit,
During operation, the induced voltage, the rotational speed, and the stator temperature are measured, and when either the induced voltage or the stator temperature cannot be measured, a value that cannot be measured by the table sheet is obtained, and the induced voltage, The rotor temperature is calculated from the stator temperature and the constant α stored in the storage unit by the following characteristic equation (2). When the rotor temperature during operation is higher than the threshold value, the operation comparison unit sends a temperature compensation command to the limiter. And a limiter to limit the current command value in the limiter.
Constant α = stator temperature difference / induced voltage difference (1)
Stator temperature difference; stator temperature difference between stator temperature A and stator temperature B measured at the same rotational speed Induced voltage difference; induced voltage difference between stator temperature A and stator temperature B measured at the same rotational speed Rotor temperature Tr = stator Temperature + induced voltage x α (2) The PM motor is driven by the three-phase alternating current output from the inverter unit, and the induced voltage, rotational speed, and stator temperature of the PM motor are measured by a voltage sensor, a magnetic pole position sensor, and a temperature sensor, respectively, and the induced voltage, Control of the PM motor that estimates the rotor temperature of the PM motor from the rotation speed and the stator temperature in the calculation comparison unit, and limits the current command value output to the current control block of the PM motor based on the estimated rotor temperature in the limiter. A method,
During the preliminary operation, the induced voltage, the rotational speed, and the stator temperature are measured, and a constant β corresponding to the rotor temperature, which is determined by the induced voltage and the rotational speed, is determined from the measured values in the calculation comparison unit by the following characteristic formula (3 ) And is stored in the storage unit, and a table sheet of induced voltage-rotational speed characteristics with the stator temperature as a parameter is created from the measured value and stored in the storage unit. Set constant β
During operation, the induced voltage, the rotational speed, and the stator temperature are measured, and when either the induced voltage or the rotational speed cannot be measured, a value that cannot be measured by the table sheet is obtained, and the induced voltage, When the constant γ is calculated from the rotational speed by the following characteristic formula (3 ′), the constant β in the threshold value stored in the storage unit in advance during the preliminary operation is compared with the constant γ during the operation, and the constant γ is smaller, A control method for a PM motor, characterized in that a temperature compensation command is output from a calculation comparison unit to a limiter, and the current command value is limited by the limiter.
Constant β = induced voltage difference / rotational speed difference (3)
Induced voltage difference; difference in induced voltage between rotational speed A and rotational speed B measured at the same stator temperature Rotational speed difference; rotational speed difference between rotational speed A and rotational speed B measured at the same stator temperature Constant γ = induced Voltage / Rotation speed (3 ') In the operation comparison unit,
The constant β and the constant γ calculated by the equations (3) and (3 ′) are divided by a reference stator temperature constant β selected so that the corrected current command value becomes an appropriate value. Calculate the values of constant β ′ and constant γ ′,
In operation, the constant γ ′ in the constant γ calculated by the equation (3 ′) is compared with the value of the constant β ′ at the threshold rotor temperature. When the constant γ ′ is smaller, the limiter The PM motor control method according to claim 2, wherein the corrected current command value is calculated and output by the characteristic formula (4) to limit the current command value.
Current command value after correction = current command value × γ ′ (4)

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