Electric motor and method for controlling electric motor

Abstract

The present invention provides an electric motor allowing stable drive control to be performed even when, in multipole motors, a resolver is used in a position sensor and combinations are realized in which the pole number ratio between the number of poles in the electric motor and the number of poles in the resolver is an indivisible non-integer multiple. This electric motor is characterized in that: said electric motor comprises an electric motor body, a position sensor that detects the position of a rotor of the electric motor body, and a control device that controls driving of the electric motor body; the control device includes a vector control unit that calculates a voltage command value on the basis of information on current flowing in the electric motor body and information on the position of the rotor detected by the position sensor, and an electrical angle phase calculation unit that calculates the electrical angle phase of the electric motor body; the electrical angle phase conversion unit includes an electrical angle conversion unit that converts sensor phase information, which is phase information for the motor body as acquired from the position sensor, into electrical angle phase information, which is phase information for the electrical angle of the rotor, in accordance with the pole number ratio, which is the ratio of the number of rotor poles, which is the number of poles of the rotor, and the number of position sensor poles, which is the number of poles of the position sensor, and outputs the electrical angle phase information, a rotor phase estimation unit that estimates the phase information of the electrical angle of the rotor and outputs the resulting estimate as a position estimation result, a phase correction amount calculation unit that calculates a phase correction amount according to the sensor phase information and the position estimation result, and a phase correction amount addition unit that generates corrected electrical angle phase information according to the value obtained by adding the phase correction amount to the electrical angle phase information; and the phase correction amount calculation unit calculates an initial phase correction amount according to the position estimation result for when the position sensor outputs 0-degree-phase information as the sensor phase information, calculates, once the initial phase correction amount has been calculated, a correction unit amount whereby 1 is added when the sensor phase information outputted by the phase sensor when the initial value is 0 has changed from 360 degrees to 0 degrees and 1 is subtracted when the sensor phase information outputted by the phase sensor when the initial value is 0 has changed from 0 degrees to 360 degrees, calculates a unit correction amount, which is the value obtained by multiplying the pole number ratio decimal value by 360 degrees, said pole number ratio decimal value being the value of the pole number ratio after the decimal point, and calculates as the phase correction amount a value obtained by multiplying the unit correction amount by the correction unit number and adding the resulting product to the initial phase correction amount.

Description

Electric motor and control method for electric motor

[0001] The present invention relates to the configuration of an electric motor and a control method thereof, and in particular to a technique that is effective when applied to a multi-pole electric motor.

[0002] In recent years, with the increasing demand for energy conservation, AC motor control devices that drive AC motors are being applied to a wide range of applications, including home appliances, infrastructure, and industrial equipment. In particular, in the case of electric vehicles, in order to expand the interior space and battery installation space, in-wheel motors, in which the AC motor is placed inside the wheel, are being studied. In-wheel motors are being designed with multi-polarity, due to strong demand for compact size and high power density.

[0003] One type of control device that drives an AC motor uses a resolver to detect the rotational position and rotational speed of the AC motor. A resolver is attached to the rotating shaft and is a sensor that converts the mechanical angle of the rotating shaft into an electrical signal using electromagnetic induction. It has excellent environmental resistance and is being used in a wide range of applications.

[0004] However, due to the principle of using electromagnetic induction, resolvers have an upper limit to the number of poles they can support. Also, there are cases where a resolver with a small number of poles is combined with a multi-polarized electric motor.

[0005] As background art in this technical field, there is, for example, a technique such as that described in Patent Document 1. Patent Document 1 discloses "an AC motor control device capable of stably performing vector control of a multi-polar AC motor."

[0006] Furthermore, Patent Document 2 discloses a "motor device configured to be capable of detecting the rotational position of the motor rotor more accurately while suppressing increases in the size and cost of the device."

[0007] In Patent Documents 1 and 2, in order to perform sensorless control using a resolver when the number of poles of the resolver is small compared to the number of poles of the electric motor, a method is proposed in which the electric motor electrical angle phase is calculated by multiplying the resolver phase by the pole number ratio between the number of poles of the electric motor and the number of poles of the resolver.

[0008] JP 2024-021691 A JP 2014-185900 A

[0009] As described above, when a resolver is used for a multi-pole electric motor, a resolver that is compatible with a small number of poles is used.

[0010] Therefore, in Patent Documents 1 and 2, the electric motor electrical angle phase is calculated by multiplying the resolver phase by the pole number ratio between the number of poles of the electric motor and the number of poles of the resolver, which makes it possible to calculate the electric motor electrical angle phase when the pole number ratio between the number of poles of the electric motor and the number of poles of the resolver is an integer multiple.

[0011] However, when the pole ratio between the number of poles of the motor and the number of poles of the resolver is a non-integer that cannot be divided evenly, it becomes difficult to calculate the electrical angle phase of the motor, making it difficult to stably control a multi-polarized motor, and there is room for improvement.

[0012] Therefore, an object of the present invention is to provide an electric motor and a control method thereof that can stably control driving of a multi-polarized electric motor, even in the case of a combination in which the pole number ratio between the number of poles of the electric motor and the number of poles of the resolver is an indivisible non-integer multiple, while using a resolver as a position sensor.

[0013] In order to achieve the above object, the present invention provides a motor control device comprising: an electric motor body; a position sensor for detecting a position of a rotor of the electric motor body; and a control device for controlling driving of the electric motor body, wherein the control device has a vector control unit that calculates a voltage command value based on information relating to a current flowing through the electric motor body and information relating to the position of the rotor detected by the position sensor; and an electrical angle phase calculation unit that calculates an electrical angle phase of the electric motor body, wherein the electrical angle phase calculation unit comprises an electrical angle conversion unit that converts sensor phase information, which is phase information of the electric motor body obtained from the position sensor, into electrical angle phase information, which is phase information of the electrical angle of the rotor, in accordance with a pole ratio, which is the ratio between a rotor pole number, which is the number of poles of the rotor, and a position sensor pole number, which is the number of poles of the position sensor, and outputs the electrical angle phase information; and a rotor phase estimation unit that estimates the phase information of the rotor electrical angle and outputs it as a position estimation result. the phase correction amount calculation unit calculates an initial phase correction amount in accordance with the position estimation result when the position sensor outputs phase information of 0 degrees as the sensor phase information, calculates a number of correction units by adding 1 when the sensor phase information output by the position sensor changes from 360 degrees to 0 degrees and by subtracting 1 when the sensor phase information changes from 0 degrees to 360 degrees, calculates a unit correction amount by multiplying 360 degrees by a pole number ratio decimal value that is the value after the decimal point of the pole number ratio, and calculates a value by adding the initial phase correction amount to a value obtained by multiplying the unit correction amount by the number of correction units.

[0014] The present invention also provides a method for detecting a rotor phase error, the method comprising: (a) an electrical angle conversion unit converting sensor phase information, which is phase information of a motor body acquired from a position sensor, into electrical angle phase information, which is phase information of the rotor's electrical angle, in accordance with a pole ratio, which is the ratio between the rotor pole number, which is the number of poles of the rotor, and the position sensor pole number, which is the number of poles of the position sensor, and outputting the converted information; (b) a rotor phase estimation unit estimating the phase information of the rotor's electrical angle and outputting the result of position estimation; (c) a phase correction amount calculation unit calculating a phase correction amount in accordance with the sensor phase information and the result of position estimation; (d) a phase correction amount addition unit generating corrected electrical angle phase information in accordance with a value obtained by adding the phase correction amount to the electrical angle phase information; and (e) the phase correction amount calculation unit calculating the phase information after correction, the method comprising: (a) converting sensor phase information, which is phase information of a motor body acquired from a position sensor, into electrical angle phase information, which is phase information of the rotor's electrical angle, in accordance with a pole ratio, which is the ratio between the rotor pole number, which is the number of poles of the rotor, and the position sensor pole number, which is the number of poles of the position sensor, and outputting the converted information as a result of position estimation. (f) a step in which the phase correction amount calculation unit, after calculating the initial phase correction amount in the step (e), calculates a correction unit number by adding 1 when the sensor phase information output by the position sensor changes from 360 degrees to 0 degrees and subtracting 1 when the sensor phase information changes from 0 degrees to 360 degrees; (g) a step in which the phase correction amount calculation unit calculates a unit correction amount which is a value obtained by multiplying 360 degrees by a pole number ratio decimal value which is a value after the decimal point of the pole number ratio; and (h) a step in which the phase correction amount calculation unit calculates a value obtained by adding the initial phase correction amount to a value obtained by multiplying the unit correction amount by the number of correction units.

[0015] According to the present invention, it is possible to realize an electric motor and a control method thereof that can stably control driving of a multi-polar electric motor, even in the case of a combination in which a resolver is used as a position sensor and the pole number ratio between the number of poles of the electric motor and the number of poles of the resolver is an indivisible non-integer multiple.

[0016] This makes it possible to achieve both a compact, high-power density and high reliability for the motor.

[0017] Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments.

[0018] 5 is a block diagram showing a schematic configuration of an AC motor according to a first embodiment of the present invention. FIG. 6 is a block diagram showing the configuration of an electrical angle phase calculation unit in a conventional AC motor. FIG. 7 is a diagram showing example waveforms when the pole number ratio of the number of motor pole pairs and the shaft multiplier angle of a position sensor in a conventional AC motor is an integer multiple. FIG. 8 is a diagram showing example waveforms when the pole number ratio of the number of motor pole pairs and the shaft multiplier angle of a position sensor in a conventional AC motor is a non-integer multiple that is not divisible. FIG. 9 is a block diagram showing the configuration of the electrical angle phase calculation unit 22 (222) of FIG. 1. FIG. 10 is a diagram showing example waveforms when the pole number ratio of the number of motor pole pairs and the shaft multiplier angle of a position sensor in the AC motor of FIG. 1 is a non-integer multiple that is not divisible. FIG. 11 is a diagram showing an electric vehicle according to a second embodiment of the present invention. FIG. 12 is a diagram showing an electric aircraft according to a third embodiment of the present invention. FIG. 13 is a diagram showing a schematic diagram showing calculation of an initial state immediately after start-up in the electrical angle phase calculation unit 222 of FIG.

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings, the same components are designated by the same reference numerals, and detailed description of overlapping parts will be omitted.

[0020] An electric motor and a control method thereof according to a first embodiment of the present invention will be described with reference to Figures 1 to 6 and Figure 9. Figures 2 to 4 are diagrams showing the configuration of a conventional AC electric motor and its control, shown to make the present invention easier to understand.

[0021] <<Overall Configuration>> FIG. 1 is a block diagram showing a schematic configuration of an AC motor according to a first embodiment of the present invention.

[0022] In this embodiment, an example will be described in which an AC motor (motor body) 1 is driven and controlled by a control device 2 of the present invention.

[0023] As shown in FIG. 1, the control device 2 of the present invention includes, as its main components, a vector control unit 21, an electrical angle phase calculation unit 22, and an electrical angle rotation speed calculation unit 23.

[0024] In the control device 2, a vector control unit 21 calculates a voltage command value based on information from a current detection unit 4 that detects the current flowing through the AC motor 1 and information from a position sensor (resolver) 5 that detects the position of the rotation shaft of the AC motor 1. Based on the voltage command value calculated by the vector control unit 21, an inverter 3 supplies AC power to the AC motor 1.

[0025] The vector control unit 21 can be realized by using a general vector control, and the control method is not specified.

[0026] <Problems with Conventional Multipolar AC Motors> Problems with conventional multipolar AC motors will be described in detail with reference to FIGS. 2 to 4. FIG.

[0027] Fig. 2 is a block diagram showing the configuration of an electrical angle phase calculation unit 221 in a conventional AC motor. Fig. 3 is a diagram showing an example of waveforms when the pole number ratio of the motor pole pair number to the position sensor shaft multiplier angle is an integer multiple in a conventional AC motor. Fig. 4 is a diagram showing an example of waveforms when the pole number ratio of the motor pole pair number to the position sensor shaft multiplier angle is a non-integer multiple that cannot be divided evenly in a conventional AC motor.

[0028] As mentioned above, a multi-polar design is one method for making the AC motor 1 smaller and more powerful. However, if a resolver that uses electromagnetic induction is used as the position sensor 5 that detects the position of the rotating shaft, there is, in principle, an upper limit to the number of poles that can be supported.

[0029] Here, the value obtained by dividing the number of poles of the AC motor 1 by 2 is called the pole pair number P.P. Furthermore, the value obtained by multiplying the mechanical rotation speed ωr of the AC motor 1 by the pole pair number P.P., ωr×P.P., is called the electrical angle rotation speed. Vector control by the vector control unit 21 is calculated based on this electrical angle rotation speed ωr×P.P.

[0030] Furthermore, for the resolver, which is the position sensor 5, the ratio of how many rotations of phase are output when the AC motor 1 makes one mechanical rotation is called the shaft multiplier X. For example, when X=2, a phase equivalent to two rotations is output when the AC motor 1 makes one rotation, the shaft multiplier is called 2X.

[0031] As described above, there is an upper limit to the shaft angle multiplier X of the resolver, so when the AC motor 1 is multipolarized, the number of pole pairs P.P. becomes larger than the shaft angle multiplier X. In a conventional multipolarized AC motor, as shown in FIG. 2 , the electrical angle phase calculation unit 221 calculates the electrical angle phase 221A of the AC motor by multiplying pole ratio information N, which is obtained by dividing the number of pole pairs P.P. by the shaft angle multiplier X, by the resolver phase 5A from the position sensor 5.

[0032] FIG. 3 shows an example in which the pole pair number P.P. is 4, the shaft angle multiplier X is 2, and the pole ratio information N is 2. As shown in FIG. 3, the horizontal axis represents the mechanical rotation angle of the AC motor (motor shaft mechanical angle phase), and the vertical axis represents the motor electrical angle information in the top row of FIG. 3. As the AC motor mechanically rotates from 0 degrees to 360 degrees, it repeats from 0 degrees to 360 degrees four times. Furthermore, the vertical axis represents the resolver angle information in the middle row of FIG. 3. This repeats from 0 degrees to 360 degrees twice. In the case of FIG. 3, since the pole ratio information N is 2, multiplying the resolver angle information by the pole ratio information N of 2 makes it possible to obtain an electrical angle conversion phase synchronized with the motor electrical angle phase, as shown in the bottom row of FIG. 3.

[0033] 4 shows an example in which the number of pole pairs P.P. is 3, the shaft angle multiplier X is 2, and the pole ratio information N is a non-divisible, non-integer multiple of 1.5. In this case, because the pole ratio information N is 1.5, when the resolver angle information is multiplied by the pole ratio information N of 1.5, the electrical angle conversion phase becomes 0 when the AC motor mechanically rotates to 180 degrees, as shown in the bottom part of FIG. 4. This makes it difficult to obtain an electrical angle conversion phase that is synchronized with the electric motor electrical angle phase. In other words, a torque error occurs due to such an error between the electric motor electrical angle phase and the electric angle conversion phase.

[0034] <Configuration of Electrical Angle Phase Calculation Unit and Control Method Thereof> Therefore, in this embodiment, when the pole ratio obtained by dividing the number of pole pairs P.P. of AC motor 1 by the shaft multiplication angle X of the resolver serving as position sensor 5 is a non-integer multiple, the motor electrical angle phase and the resolver phase angle are multiplied by the pole ratio to correct the electrical angle conversion phase.

[0035] Fig. 5 is a block diagram showing the configuration of the electrical angle phase calculation unit 22 (222) in Fig. 1. Fig. 6 is a diagram showing example waveforms when the pole ratio of the motor pole pair number and the position sensor shaft multiplier angle in the AC motor of Fig. 1 is a non-integral multiple that cannot be divided evenly. Fig. 6 shows example waveforms obtained by the correction method of the present invention when the pole pair number P.P. is 3, the shaft multiplier angle X is 2, and the pole ratio information N is a non-integral multiple of 1.5 that cannot be divided evenly.

[0036] As shown in FIG. 5 , the electrical angle phase calculation unit 222 of this embodiment includes a phase correction number generation unit 2221, a phase correction calculation unit 2222, a phase correction addition unit 2223, an initial position estimation unit 2224, a phase correction number initial value generation unit 2225, and an electrical angle conversion unit 2226.

[0037] The phase correction number generation unit 2221 adds 1 (+1) to the phase correction number when the resolver phase changes from 360 degrees to 0 degrees, and subtracts 1 (-1) from the phase correction number when the resolver phase changes from 0 degrees to 360 degrees.

[0038] In the waveform example of Fig. 6, the phase correction number 2221A is "0" when the motor shaft mechanical angle phase is between 0 degrees and 180 degrees, and is "1" when it is between 180 degrees and 360 degrees. In the example of Fig. 6, since the resolver shaft multiplier X is 2, there are two phase correction numbers, "0" and "1." In general, the number of phase correction numbers required is equal to the number of denominators obtained by reducing the number of pole pairs P.P. / shaft multiplier angle X.

[0039] The phase correction calculation unit 2222 calculates a phase correction calculation value 2222A from 2221A×n×360 degrees using the phase correction number 2221A and the pole pair number P.P. / axis multiplier angle X (decimal part n).

[0040] In the waveform example of FIG. 6, when the phase correction number 2221A is "1", the phase correction calculation value 2222A is 1 x 0.5 x 360 = 180 degrees.

[0041] The phase correction adding unit 2223 adds the phase correction calculation value 2222A to the electrical angle conversion phase obtained by converting the resolver phase 5A by the electrical angle converting unit 2226, and calculates the electrical angle conversion phase correction value 222A.

[0042] In the waveform example of Figure 6, when the electric motor shaft mechanical angle phase is between 180 degrees and 360 degrees, the phase correction calculation value 2222A of 180 degrees is added to the electrical angle conversion phase shown by the dotted line to obtain the electrical angle conversion phase correction value 222A as shown by the thick solid line.

[0043] In this way, the electrical angle conversion phase correction value 222A obtained by correcting the electrical angle conversion phase makes it possible to obtain a phase angle synchronized with the electric motor electrical angle phase.

[0044] Here, if the initial value of the electric motor shaft mechanical angle phase is 180 degrees to 360 degrees as shown in the waveform example of Fig. 3 immediately after startup of the control device 2, the desired value for the phase correction number 2221A is "1". However, since it is immediately after startup, the initial value of the phase correction number may be "0". In this case, in the waveform example of Fig. 6, a phase correction of 0 degrees occurs instead of a 180-degree phase correction, resulting in an error of 180 degrees between the phase correction calculation value 2222A and the actual electric motor electrical angle phase.

[0045] FIG. 9 is a diagram schematically showing the calculation of the initial state immediately after startup in the electrical angle phase calculation unit 222 of FIG.

[0046] Therefore, in the configuration of this embodiment, immediately after startup of the control device 2, the initial value of the phase correction number is generated by the initial position estimator 2224 and the phase correction number initial value generator 2225. As shown in Fig. 9 , immediately after startup of the control device 2, the initial position estimator (rotor phase estimator) 2224 outputs 0 as the position estimation result if the estimated phase is 0 degrees, and outputs 1 as the position estimation result if the estimated phase is 180 degrees.

[0047] 6, if the initial value of the electric motor shaft mechanical angle phase is between 180 degrees and 360 degrees immediately after startup of the control device 2, an error of 180 degrees occurs between the phase correction calculation value 2222A and the actual electric motor electrical angle phase. In this state, if the initial value is estimated based on the phase correction calculation value 2222A, an error of 180 degrees occurs in the initial position.

[0048] Therefore, if the initial value of the phase correction number generator 2221 is set to "1," it becomes possible to synchronize the calculated phase correction value 2222A with the actual electric motor electrical angle phase. Generally speaking, the initial value of the phase correction number generator 2221 is set by comparing the calculated phase correction value 2222A (M×360°×n) with the initial position estimation error, where n is the number of pole pairs P.P. / a decimal point in the shaft multiplier angle X and the phase correction number is 0 to M.

[0049] As described above, the electrical angle conversion phase correction value 222A is calculated using the phase correction calculation value 2222A, and the AC motor 1 is controlled by the vector control unit 21 via the inverter 3 based on this.

[0050] This makes it possible to suppress axial errors and torque errors that occur when the number of pole pairs of the motor and the shaft multiplication angle of the resolver are non-integer multiples, thereby stabilizing vector control.

[0051] The electric motor of this embodiment includes an electric motor (AC motor) 1, a position sensor 5 that detects the position of the rotor of the electric motor 1, and a control device 2 that controls the driving of the electric motor 1. The control device 2 has a vector control unit 21 that calculates a voltage command value based on information about the current flowing through the electric motor 1 and information about the rotor position detected by the position sensor 5, and an electrical angle phase calculation unit 22 (222) that calculates the electrical angle phase of the electric motor 1. The electrical angle converter 2226 converts sensor phase information (resolver phase 5A), which is phase information of the electric motor main body 1 acquired from the position sensor 5, into electrical angle phase information (electrical angle phase 221A), which is phase information of the electrical angle of the rotor, in accordance with a pole ratio, which is the ratio between the number of rotor poles, which is the number of poles of the rotor, and the number of position sensor poles, which is the number of poles of the position sensor 5, and outputs the converted information; a rotor phase estimator (initial position estimator 2224) estimates the phase information of the electrical angle of the rotor and outputs it as a position estimation result; The phase correction amount calculation unit (phase correction number generation unit 2221, phase correction calculation unit 2222, phase correction number initial value generation unit 2225) calculates a phase correction amount according to the position estimation result and the electrical angle phase information (electrical angle phase 221A), and a phase correction amount addition unit (phase correction addition unit 2223) generates corrected electrical angle phase information according to a value obtained by adding the phase correction amount to the electrical angle phase information (electrical angle phase 221A). When the position sensor 5 outputs phase information of 0 degree as the sensor phase information (resolver phase 5A), the phase correction amount calculation unit An initial phase correction amount is calculated according to the position estimation result, and after calculating the initial phase correction amount, a correction unit number is calculated by adding 1 when the sensor phase information (resolver phase 5A) output by position sensor 5, which has an initial value of 0, changes from 360 degrees to 0 degrees and subtracting 1 when the sensor phase information changes from 0 degrees to 360 degrees. A unit correction amount is calculated by multiplying 360 degrees by the pole number ratio decimal value, which is the value after the decimal point of the pole number ratio. A value obtained by multiplying the initial phase correction amount by the unit correction amount and the number of correction units is then calculated as the phase correction amount.

[0052] This makes it possible to calculate the electrical angle phase information of the AC motor 1 even in the case where the number of pole pairs of the multi-polarized AC motor (motor main body) 1 and the pole number ratio of the shaft multiplication angle of the resolver, which is the position sensor 5, are non-integral multiples that cannot be divided evenly. Furthermore, by using the calculated electrical angle phase information, it becomes possible to stably vector control the multi-polarized AC motor 1.

[0053] <<Application to Electric Vehicles and Effects thereof>> An electric vehicle according to a second embodiment of the present invention will be described with reference to Fig. 7. Fig. 7 is a diagram showing an electric vehicle 100 according to this embodiment.

[0054] As shown in FIG. 7 , by applying a small-sized, high-power density AC motor 1 as in-wheel motors 101 a, 101 b arranged on the wheels of an electric vehicle 100 and further incorporating the control device 2 described in the first embodiment, it is possible to expand the interior space of the vehicle and the space for installing the battery.

[0055] Furthermore, vector control can be performed using a resolver with a small number of poles even for AC motors that have been made multi-polar in order to achieve smaller size and higher power density, making it possible to build a control configuration at low cost without using a dedicated position sensor that supports multi-pole operation.

[0056] <Application to Electric Aircraft and Its Effects> An electric aircraft according to a third embodiment of the present invention will be described with reference to Fig. 8. Fig. 8 is a diagram showing an electric aircraft 110 according to this embodiment.

[0057] As shown in FIG. 8, by applying a small-sized, high-power density AC motor 1 to electric propulsion fans 111a, 111b of an electric aircraft 110 and further incorporating the control device 2 described in the first embodiment, it is possible to improve the electric cost of the jet engine and reduce CO ２ It will be possible to reduce emissions.

[0058] Furthermore, vector control can be performed using a resolver with a small number of poles even for AC motors that have been made multi-polar in order to achieve smaller size and higher power density. This makes it possible to build a highly reliable and stable control configuration at low cost using a resolver with high environmental resistance in harsh environments such as high altitudes and those with a lot of vibration due to fan operation.

[0059] The present invention is not limited to the above-described embodiments, but includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0060] 1...AC motor (motor body), 2...control device, 3...inverter, 4...current detection unit, 5...position sensor (resolver), 5A...resolver phase, 21...vector control unit, 22, 221, 222...electrical angle phase calculation unit, 23...electrical angle rotation speed calculation unit, 100...electric vehicle, 101a, 101b...in-wheel electric motor, 110...electric aircraft, 111a, 111b...electric propulsion fan, 221A...electrical angle phase, 222A...electrical angle conversion phase correction value, 2221...phase correction number generation unit, 2221A...phase correction number, 2222...phase correction calculation unit, 2222A...phase correction calculation value, 2223...phase correction addition unit, 2224...initial position estimation unit, 2225...phase correction number initial value generation unit, 2226...electrical angle conversion unit.

Claims

1. An electric motor comprising: an electric motor body; a position sensor that detects the position of a rotor of the electric motor body; and a control device that controls the drive of the electric motor body, wherein the control device has a vector control unit that calculates a voltage command value based on information related to a current flowing through the electric motor body and information related to the position of the rotor detected by the position sensor; and an electrical angle phase calculation unit that calculates an electrical angle phase of the electric motor body, wherein the electrical angle phase calculation unit has an electrical angle conversion unit that converts sensor phase information, which is phase information of the electric motor body obtained from the position sensor, into electrical angle phase information, which is phase information of the electrical angle of the rotor, in accordance with a pole ratio, which is the ratio between the rotor pole number, which is the number of poles of the rotor, and the position sensor pole number, which is the number of poles of the position sensor, and outputs the electrical angle phase information; a rotor phase estimator that estimates the phase information of the rotor electrical angle and outputs it as a position estimation result; a phase correction amount calculation unit that calculates a phase correction amount in accordance with the sensor phase information and the position estimation result; and a phase correction amount addition unit that generates corrected electrical angle phase information in accordance with a value obtained by adding the phase correction amount to the electrical angle phase information. the phase correction amount calculation unit calculates an initial phase correction amount according to the position estimation result when the position sensor outputs phase information of 0 degrees as the sensor phase information; after calculating the initial phase correction amount, calculates a number of correction units by adding 1 when the sensor phase information output by the position sensor, with an initial value of 0, changes from 360 degrees to 0 degrees and subtracting 1 when the sensor phase information changes from 0 degrees to 360 degrees; calculates a unit correction amount which is a value obtained by multiplying 360 degrees by a pole number ratio decimal value which is a value after the decimal point of the pole number ratio; and calculates a value obtained by adding the initial phase correction amount to a value obtained by multiplying the unit correction amount by the number of correction units as the phase correction amount.

2. An electric motor according to claim 1, wherein the rotor phase estimation unit outputs 0 as the position estimation result if the estimated phase is 0 degrees immediately after the start of the control device, and outputs 1 as the position estimation result if the estimated phase is 180 degrees.

3. An electric motor according to claim 1, wherein the position sensor is a resolver.

4. The electric motor according to claim 1, wherein the pole ratio is a non-integral multiple that cannot be divided.

5. The electric motor according to claim 1, characterized in that it is mounted on an electric vehicle or an electric aircraft.

6. A method for controlling an electric motor, the method comprising the following steps: (a) an electrical angle conversion unit converting sensor phase information, which is phase information of the electric motor body acquired from a position sensor, into electrical angle phase information, which is phase information of the electrical angle of the rotor, in accordance with a pole ratio, which is the ratio between the rotor pole number, which is the number of poles of the rotor, and the position sensor pole number, which is the number of poles of the position sensor, and outputting the converted information; (b) a rotor phase estimation unit estimating phase information of the rotor electrical angle and outputting the result of position estimation; (c) a phase correction amount calculation unit calculating a phase correction amount in accordance with the sensor phase information and the result of position estimation; (d) a phase correction amount addition unit generating corrected electrical angle phase information in accordance with a value obtained by adding the phase correction amount to the electrical angle phase information; (e) a phase correction amount calculation unit calculating an initial phase correction amount in accordance with the result of position estimation when the position sensor outputs phase information of 0 degrees as the sensor phase information; (f) a step in which the phase correction amount calculation unit calculates a correction unit number by adding 1 when the sensor phase information output by the position sensor changes from 360 degrees to 0 degrees and subtracting 1 when the sensor phase information changes from 0 degrees to 360 degrees, after calculating an initial phase correction amount in step (e); (g) a step in which the phase correction amount calculation unit calculates a unit correction amount which is a value obtained by multiplying 360 degrees by a pole number ratio decimal value which is a value after the decimal point of the pole number ratio; and (h) a step in which the phase correction amount calculation unit calculates a value obtained by adding the initial phase correction amount to a value obtained by multiplying the unit correction amount and the correction unit number, as the phase correction amount.

7. A method for controlling an electric motor as set forth in claim 6, characterized in that the rotor phase estimation unit outputs 0 as the position estimation result if the estimated phase is 0 degrees immediately after startup of the control device for the electric motor, and outputs 1 as the position estimation result if the estimated phase is 180 degrees.

8. A method for controlling an electric motor according to claim 6, wherein the position sensor is a resolver.

9. A method for controlling an electric motor according to claim 6, wherein the pole number ratio is a non-integral multiple that cannot be divided evenly.

10. A method for controlling an electric motor according to claim 6, wherein the electric motor is mounted on an electric vehicle or an electric aircraft.

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