Electromechanical system

Abstract

This electric-powered machine system is provided with an electric-powered machine, an electric power converter, and a control unit. The electric-powered machine comprises a stator including a coil, and a rotor which includes a magnet and which is capable of rotating about the stator. The electric power converter inputs electric power to the coil of the electric-powered machine. The control unit controls the electric power converter. The control unit comprises an output unit and an adjusting unit. The output unit outputs a control signal for operating the electric power converter to the electric power converter. The adjusting unit adjusts a phase of the control signal that determines the timing at which electric power is input to the coil of the electric-powered machine. The adjusting unit adjusts the phase such that the magnitude of the electric power tends toward an extreme value.

Description

Technical Field

[0001] The present disclosure relates to an electromechanical system.

Background Art

[0002] Conventionally, an electromechanical machine including a stator and a rotor has been known (see, for example, Patent Document 1). In the electromechanical machine described in Patent Document 1, the position of the rotor is detected by determining the polarity of the rotor poles by using the hysteresis characteristics of the motor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the electromechanical machine as described above, in order to improve performance such as efficiency, for example, it is required to input electric power in accordance with the timing when the rotor is positioned at a predetermined position. However, it is difficult to detect the position of the rotor with high accuracy or to control the timing of the input of electric power with high accuracy. If the timing when the rotor is positioned at a predetermined position and the timing of the input of electric power are deviated, wasteful power consumption may occur, and as a result, the performance of the electromechanical machine may be degraded.

[0005] An object of the present disclosure is to provide an electromechanical system capable of improving performance.

Means for Solving the Problems

[0006] An electromechanical system according to one aspect of the present disclosure includes an electromechanical machine having a stator including coils and a rotor including magnets and rotatable with respect to the stator, a power converter for inputting and outputting power to and from the coils, and a control unit for controlling the power converter. The control unit has an output unit that outputs a signal for operating the power converter to the power converter, and a correction unit that corrects the phase of the signal that determines the timing of power input and output to and from the coils. The correction unit corrects the phase so that the magnitude of the power tends toward an extreme value.

[0007] In this electromechanical system, the correction unit corrects the phase of the signal so that the magnitude of the power input and output to and from the coils tends toward an extreme value. When the magnitude of the power reaches an extreme value, it is assumed that the loss of the electromechanical machine is minimized, that is, the phase of the signal with respect to the position of the rotor is optimal. Thereby, even without detecting the position of the rotor with high accuracy, it is possible to suppress the consumption of wasteful power by optimizing the phase of the signal. Therefore, according to this electromechanical system, the performance can be improved.

[0008] The electromechanical machine is an electric motor, the extreme value is a minimum value, and when the power becomes smaller as a result of correcting the phase in the first direction, the correction unit corrects the phase in the first direction again, and when the power becomes larger as a result of correcting the phase in the first direction, the correction unit may correct the phase in a second direction opposite to the first direction. According to this configuration, when the electromechanical machine is an electric motor, the correction direction of the phase can be changed based on the change in power due to the correction of the phase. Thereby, the magnitude of the power can be made to tend toward the minimum value.

[0009] When the phase becomes larger than the maximum limit value as a result of correcting the phase, the correction unit may set the maximum limit value as the corrected phase, and when the phase becomes smaller than the minimum limit value as a result of correcting the phase, the correction unit may set the minimum limit value as the corrected phase. According to this configuration, it is possible to suppress the phase of the signal from deviating to an unintended range.

[0010] The correction unit may include an execution mode for performing phase correction and a pause mode for pausing the phase correction. According to this configuration, it is possible to switch to the execution mode only when it is necessary to correct the phase of the signal with respect to the position of the rotor.

[0011] The electromechanical machine is a generator, the extreme value is the maximum value, and when the power increases as a result of correcting the phase in the first direction, the correction unit may correct the phase in the first direction again, and when the power decreases as a result of correcting the phase in the first direction, the correction unit may correct the phase in the second direction opposite to the first direction. According to this configuration, when the electromechanical machine is a generator, it is possible to change the phase correction direction based on the change in power due to the phase correction. Thereby, the magnitude of the power can be made to approach the maximum value.

[0012] An electromechanical system according to an aspect of the present disclosure includes an electromechanical machine having a stator including a coil and a rotor including a magnet and rotatable with respect to the stator, a power converter for inputting and outputting power to and from the coil, and a control unit for controlling the power converter. The control unit has an output unit for outputting a signal for operating the power converter to the power converter, and a correction unit for correcting the phase of the signal that determines the timing of power input and output to and from the coil. The correction unit corrects the phase so that an index value correlated with the current input to and output from the coil approaches an extreme value.

[0013] In this electromechanical system, the correction unit corrects the phase of the signal so that an index value correlated with the current input to and output from the coil approaches an extreme value. When the index value correlated with the current input to and output from the coil reaches an extreme value, it is assumed that the loss of the electromechanical machine is minimized, that is, the phase of the signal with respect to the position of the rotor is optimal. Thereby, even without detecting the position of the rotor with high accuracy, it is possible to suppress the consumption of wasted power by optimizing the phase of the signal. Therefore, according to this electromechanical system, the performance can be improved.

[0014] The index value may be a division value obtained by dividing the current by the torque of the electromechanical device. As a result, the change amount of the index value per change amount of the phase becomes relatively large, so that the phase control can be performed with higher sensitivity.

[0015] The index value may be the current. By using the current as the index value, the performance of the electromechanical system can be improved.

[0016] The index value may be a multiplication value obtained by multiplying the alternating current input to and output from the coil by the alternating voltage input to and output from the coil. By using the multiplication value of the alternating current and the alternating voltage as the index value, the performance of the electromechanical system can be improved.

Effect of the Invention

[0017] According to the present disclosure, it becomes possible to provide an electromechanical system capable of improving performance.

Brief Description of the Drawings

[0018]

Figure 1

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[0019] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In each figure, the same or corresponding parts are denoted by the same reference numerals, and redundant descriptions are omitted.

[0020] [First Embodiment] As shown in FIG. 1, the electromechanical system 1A includes an electromechanical device 2, a power source 3, and a drive device 4A. The electromechanical system 1A is applied to, for example, an electric compressor, an electric blower, or a vehicle (mobile body). The electromechanical device 2 is an electric motor. The electromechanical device 2 has a stator (motor stator) and a rotor (motor rotor) rotatable with respect to the stator. The rotor has a shaft and a permanent magnet provided on the shaft. The stator surrounds the rotor in the circumferential direction. The stator has a plurality of coils and an iron core.

[0021] When electric power is supplied to the coils of the stator, the stator generates a magnetic field. As a result of the circumferential force acting on the rotor by this magnetic field, torque is applied to the rotor. The rotor rotates by the action of the torque. The electromechanical device 2 has characteristics capable of corresponding to high-speed rotation of the rotor (for example, 100,000 to 200,000 rpm). The power source 3 is a DC power source. The power source 3 is, for example, a storage battery.

[0022] The drive device 4A includes a power converter 5 and a control device 6A. The power converter 5 is connected to the electromechanical machine 2 and the power supply 3. The power converter 5 inputs the power output from the power supply 3 to the coils of the electromechanical machine 2. That is, the power output from the power supply 3 is input to the electromechanical machine 2 via the power converter 5. The power converter 5 functions as an inverter. The power converter 5 converts the DC power output from the power supply 3 into AC power. The power converter 5 inputs the AC power to the electromechanical machine 2. The power converter 5 has, for example, a switch circuit. The switch circuit has, for example, semiconductor switches such as MOSFETs or IGBTs. The power converter 5 supplies AC power to the electromechanical machine 2 by, for example, the PWM control method.

[0023] The control device 6A includes a voltage detection unit 61, a current detection unit 62, and a control unit 60. The voltage detection unit 61 is connected between the power converter 5 and the power supply 3. The voltage detection unit 61 detects the DC voltage V output from the power supply 3. The voltage detection unit 61 transmits a signal related to the detected voltage V to a correction unit 64 described later.

[0024] The current detection unit 62 is connected between the power converter 5 and the power supply 3. The current detection unit 62 detects the DC current I output from the power supply 3. The current detection unit 62 transmits a signal related to the detected current I to the correction unit 64.

[0025] The control unit 60 controls the power converter 5. The control unit 60 is, for example, a computer device including a processor (such as a CPU, etc.) and a memory (such as a ROM, RAM, etc.). The control unit 60 has an output unit 63 and a correction unit 64 as functional components. The output unit 63 outputs a signal (hereinafter referred to as a "control signal") for operating the power converter 5 to the power converter 5.

[0026] As shown in FIG. 2, the control signal is, for example, a PWM control signal. The output unit 63 generates signals (P) and signals (N) for each of the plurality of semiconductor switches of the power converter 5. As an example, each of the signals (P) and signals (N) has a conduction period of 120°, and in the first half of the 60° period, ON / OFF is repeated, and in the second half of the 60° period, it is turned ON. The output unit 63 outputs the control signal to the power converter 5. The power converter 5 converts DC power into AC power according to the control signal, and inputs the AC power to the coil of the electromechanical device 2. Note that the timing of power input to the coil of the electromechanical device 2 coincides with the timing when the control signal is output to the power converter 5.

[0027] The correction unit 64 corrects the phase of the control signal with respect to the position of the rotor. The position of the rotor refers to the angle by which the rotor has rotated with respect to the stator. As an example, when the rotor has rotated 90° from the reference position (0°) of the rotor with respect to the stator, the position of the rotor is 90°. The position of the rotor is detected by, for example, a resolver. During one rotation (360° rotation) of the rotor with respect to the stator, for example, two cycles of resolver signals are output.

[0028] The phase of the control signal with respect to the position of the rotor (hereinafter simply referred to as "phase") refers to the timing at which the control signal is output to the power converter 5 with respect to the position of the rotor. As an example, when the control signal is output to the power converter 5 at the timing when the position of the rotor is 90°, the phase θ is 90°. That is, the phase θ determines the timing of power input to the coil of the electromechanical device 2.

[0029] In other words, when the timing when the position of the rotor is 90° coincides with the rising timing of one cycle of the control signal (for example, the start timing of the first half 60° period of the signal (P)), the phase θ is 90°.

[0030] The correction unit 64 outputs a signal related to the corrected phase θ to the output unit 63. The output unit 63 outputs a control signal to the power converter 5 at the timing when the rotor is positioned at the position corresponding to the corrected phase θ. As an example, when the phase θ is 90°, the output unit 63 outputs a control signal to the power converter 5 at the timing when the position of the rotor is 90°. The power converter 5 inputs the power output from the power supply 3 to the electromechanical machine 2 according to the control signal. As an example, the power converter 5 starts the input of power to the electromechanical machine 2 at the timing when the position of the rotor is 90°. In other words, when the phase θ is 90°, the power converter 5 inputs power to the electromechanical machine 2 so that the timing when the position of the rotor is 90° coincides with the rising timing of the control signal for one cycle. Thereby, a rotational torque is generated in the rotor at the timing when the position of the rotor is 90°.

[0031] Hereinafter, the correction of the phase θ by the correction unit 64 will be described in detail. The correction unit 64 calculates the power input to the electromechanical machine 2 (hereinafter simply referred to as "power") based on the signal related to the voltage V transmitted from the voltage detection unit 61 and the signal related to the current I transmitted from the current detection unit 62.

[0032] The correction unit 64 corrects the phase θ so that the magnitude of the power tends towards an extreme value. The extreme value refers to the maximum value or the minimum value. In the present embodiment, the extreme value is the minimum value. As shown in FIG. 3, the magnitude of the power decreases as the phase θ increases, reaches the minimum value M1, and then tends to increase. When the phase θ approaches the optimum value, the power factor of the electromechanical machine 2 improves and the loss decreases. As a result, the magnitude of the power approaches the minimum value M1. In other words, when the magnitude of the power becomes the minimum value M1, it is assumed that the phase θ is at the optimum value.

[0033] The correction unit 64 corrects the phase θ based on the change in power. The correction unit 64 increases or decreases the phase θ by a predetermined correction width (correction amount). That is, the phase θ increases or decreases by the correction width each time the correction is performed by the correction unit 64. In the present embodiment, the correction unit 64 adds or subtracts the phase correction amount (correction width) with respect to the reference phase in control. In other words, the correction unit 64 corrects so as to maximize the power with respect to the reference phase in control. In the present embodiment, the direction in which the phase θ increases is referred to as the first direction, and the direction in which the phase θ decreases is referred to as the second direction. In the present embodiment, switching the first direction to the second direction and switching the second direction to the first direction are referred to as reversal of the correction direction.

[0034] When the power becomes small, the correction unit 64 maintains the correction direction, and when the power becomes large, the correction unit 64 reverses the correction direction. Specifically, as a result of correcting the phase θ in the increasing direction (first direction), when the power becomes small, the correction unit 64 corrects the phase θ in the increasing direction again. As a result of correcting the phase θ in the increasing direction, when the power becomes large, the correction unit 64 corrects the phase θ in the decreasing direction (second direction opposite to the first direction).

[0035] As a result of correcting the phase θ in the decreasing direction, when the power becomes small, the correction unit 64 corrects the phase θ in the decreasing direction again. As a result of correcting the phase θ in the decreasing direction, when the power becomes large, the correction unit 64 corrects the phase θ in the increasing direction. In this way, the correction unit 64 increases or decreases the phase θ so that the magnitude of the power approaches the minimum value M1. The correction unit 64 performs feedback control on the phase θ based on the change in power.

[0036] The correction unit 64 corrects the phase θ, for example, every predetermined period. Specifically, the value of the power used for the correction of the phase θ is the average value for a predetermined period. The correction unit 64 calculates the average value of the power for each predetermined period. The correction unit 64 corrects the phase θ based on the average value of the power in the first period and the average value of the power in the second period after the first period. The first period and the second period may be consecutive to each other or may be separated from each other.

[0037] The correction unit 64 corrects the phase θ within a predetermined range. Specifically, when the corrected phase θ is within the predetermined range, the correction unit 64 outputs a signal related to the corrected phase θ to the output unit 63. When the corrected phase θ is greater than the maximum limit value, the correction unit 64 recognizes the maximum limit value as the corrected phase θ and outputs a signal related to the maximum limit value to the output unit 63. When the corrected phase θ is less than the minimum limit value, the correction unit 64 recognizes the minimum limit value as the corrected phase θ and outputs a signal related to the minimum limit value to the output unit 63.

[0038] The correction unit 64 includes an execution mode for executing the correction of the phase θ and a pause mode for pausing the correction of the phase θ. The correction unit 64 can switch between the execution mode and the pause mode based on the operating status of the electromechanical device 2 and the like.

[0039] Next, the processing executed in the control device 6A will be described. As shown in FIG. 4, the correction unit 64 determines whether it is in the execution mode (step S1). If YES in step S1, the correction unit 64 corrects the phase θ (step S2).

[0040] Specifically, the correction unit 64 calculates the corrected phase θ by adding the correction width to the current phase θ. The correction unit 64 determines whether the corrected phase θ is within a predetermined range. When the corrected phase θ is within the predetermined range, the correction unit 64 outputs a signal related to the corrected phase θ to the output unit 63. When the corrected phase θ is greater than the maximum limit value, the correction unit 64 outputs a signal related to the maximum limit value to the output unit 63. When the corrected phase θ is less than the minimum limit value, the correction unit 64 outputs a signal related to the minimum limit value to the output unit 63.

[0041] Subsequently, each of the voltage detection unit 61 and the current detection unit 62 detects the voltage and current output from the power supply 3 (step S3). Subsequently, the correction unit 64 calculates the power input to the electromechanical device 2 based on the signals transmitted from the voltage detection unit 61 and the current detection unit 62 (step S4).

[0042] Subsequently, the correction unit 64 determines whether the power is less than the reference value (step S5). The reference value is the value of the power calculated in the previous process. If the result in step S5 is YES, the correction unit 64 sets the current power calculated in step S4 as the new reference value. Subsequently, step S1 is executed again.

[0043] If the result in step S1 is NO, the process ends. If the result in step S5 is NO, the correction unit 64 reverses the correction direction to the second direction (step S7). After step S7 is executed, step S6 is executed. By repeating such processing, the correction of the phase θ is repeated so that the magnitude of the power input to the electromechanical device 2 approaches the minimum value M1. That is, the correction of the phase θ is repeated so that the loss in the power converter 5 approaches the minimum value, or the input power to the power converter 5 approaches the minimum value.

[0044] Note that the control unit 60 stores in advance the initial value of the phase θ, the initial value of the correction direction, and the initial value of the power. When the above processing is executed for the first time, in step S2, the correction width is added to the initial value of the phase θ, and the initial value of the correction direction is used as the correction direction. Also, in step S5, the initial value of the power is used as the reference value.

[0045] As described above, in the electromechanical system 1A, the correction unit 64 corrects the phase θ of the control signal so that the magnitude of the power input to the coil of the electromechanical device 2 approaches the minimum value M1. When the magnitude of the power reaches the minimum value M1, it is assumed that the loss of the electromechanical device 2 is minimized, that is, the phase θ is optimal. Thus, by optimizing the phase θ, it is possible to suppress the consumption of wasted power. Therefore, according to the electromechanical system 1A, the performance can be improved.

[0046] Conventionally, when driving an electromechanical device, it has been expected to detect the magnetic pole position of the rotor and generate a rotating magnetic field by passing a current through the stator coil at the optimal timing to generate a rotational torque. However, there has been a problem that due to the detection error of the magnetic pole position of the rotor or the error of the current conduction timing, the optimal value or target value of the driving current phase deviates from the true magnetic pole position of the rotor. Such a problem tends to deteriorate as the rotational speed range of the rotor increases. Further, such a problem has been the cause of performance degradation such as a decrease in the output of the electromechanical device, a decrease in the power factor, or an increase in loss due to an increase in the driving current. Furthermore, such a problem has been the cause of an unintentional strengthening (field strengthening) or weakening (field weakening) of the stator magnetic field and the rotor magnetic field, voltage shortage, or demagnetization of the magnet.

[0047] In the electromechanical system 1A, the current conduction timing (phase θ) determined from the detected value of the magnetic pole position of the rotor is corrected, and the condition for minimizing the power is maintained while constantly changing the phase. This makes it possible to suppress the deviation of the driving current phase from the optimal value or target value with respect to the true magnetic pole position of the rotor due to the error in the detected value of the magnetic pole position of the rotor or the error in the current conduction timing (phase θ). Also, it is possible to minimize the phase deviation regardless of the operating conditions. This makes it possible to suppress the risk of a decrease in the output characteristics of the electromechanical device 2, voltage shortage, or demagnetization of the magnet. According to the electromechanical system 1A, by searching for the optimal value of the driving current phase with respect to the true magnetic pole position of the rotor, it is possible to perform follow-up control so that the error of the driving current phase with respect to the true magnetic pole position of the rotor becomes the minimum value.

[0048] The electromechanical device 2 is an electric motor. The extreme value is the minimum value. When the power becomes smaller as a result of correcting the phase θ in the first direction, the correction unit 64 corrects the phase θ in the first direction again. When the power becomes larger as a result of correcting the phase θ in the first direction, the correction unit 64 corrects the phase θ in the second direction opposite to the first direction. According to this configuration, when the electromechanical device 2 is an electric motor, the correction direction of the phase θ can be changed based on the change in power due to the correction of the phase θ. Thereby, the magnitude of the power can be directed toward the minimum value.

[0049] When the phase θ becomes larger than the maximum limit value as a result of correcting the phase θ, the correction unit 64 sets the maximum limit value as the corrected phase θ. When the phase θ becomes smaller than the minimum limit value as a result of correcting the phase θ, the correction unit 64 sets the minimum limit value as the corrected phase θ. According to this configuration, it is possible to suppress the phase θ from deviating to an unintended range.

[0050] The correction unit 64 includes an execution mode for executing the correction of the phase θ and a pause mode for pausing the correction of the phase θ. According to this configuration, it is possible to switch to the execution mode only when it is necessary to correct the phase θ of the signal with respect to the position of the rotor, such as when an abnormality in vibration or output is detected.

[0051] The voltage detection unit 61 detects the DC voltage V output from the power supply 3. The current detection unit 62 detects the DC current I output from the power supply 3. Thereby, for example, compared with the case of detecting the AC voltage and the AC current supplied from the drive device 4A to the electromechanical device 2, more stable detection values of the voltage and the current can be obtained. Therefore, the correction unit 64 can determine the change in power with higher accuracy.

[0052] [Second Embodiment] As shown in FIG. 5, the electromechanical system 1B according to the second embodiment mainly differs from the electromechanical system 1A of the first embodiment in that it includes a drive device 4B instead of the drive device 4A. The drive device 4B mainly differs from the drive device 4A of the first embodiment in that it has a control device 6B instead of the control device 6A. Other configurations of the electromechanical system 1B are the same as those of the electromechanical system 1A. Hereinafter, differences between the electromechanical system 1B and the electromechanical system 1A will be described.

[0053] The control device 6B includes a power detection unit 65 and a control unit 60. The power detection unit 65 is connected between the power converter 5 and the electromechanical machine 2. The power detection unit 65 detects an AC voltage and an AC current output from the power converter 5, and calculates the power Pm output from the power converter 5. The power detection unit 65 transmits a signal regarding the calculated power Pm to the correction unit 64.

[0054] The control unit 60 further includes an arithmetic unit 66 as a functional configuration. The power detection unit 65 transmits a signal regarding the detected current Im to the arithmetic unit 66. Based on the signal transmitted from the power detection unit 65, the arithmetic unit 66 calculates the power Pi consumed by the power converter 5. The arithmetic unit 66 outputs a signal regarding the calculated power Pi to the correction unit 64. The correction unit 64 calculates the power input to the drive device 4B by adding the power Pm and the power Pi. The correction unit 64 corrects the phase θ based on the power input to the drive device 4B.

[0055] According to the electromechanical system 1B, similar to the electromechanical system 1A, the performance can be improved by optimizing the phase θ.

[0056] [Third Embodiment] As shown in FIG. 6, the electromechanical system 1C according to the third embodiment mainly differs from the electromechanical system 1A in that it includes an electromechanical device 7 instead of the electromechanical device 2 and a load 8 instead of the power source 3. Other configurations of the electromechanical system 1C are the same as those of the electromechanical system 1A. Hereinafter, the differences between the electromechanical system 1C and the electromechanical system 1A will be described.

[0057] The electromechanical device 7 is a generator. Similar to the electromechanical device 2, the electromechanical device 7 has a stator and a rotor. The rotor rotates, for example, by being driven by an engine or the like. A current flows through the coils of the stator due to the action of the magnetic field of the rotor. The electromechanical device 7 outputs AC power. The load 8 is, for example, a storage battery.

[0058] The power converter 5 inputs the power output from the electromechanical device 7 to the load 8. That is, the power output from the electromechanical device 7 is input to the load 8 via the power converter 5. The power converter 5 functions as a converter. The power converter 5 converts the AC power output from the electromechanical device 7 into DC power. The power converter 5 inputs the DC power to the load 8. Hereinafter, the power input to the load 8 is simply referred to as "power".

[0059] The correction unit 64 corrects the phase θ so that the magnitude of the power becomes an extreme value. In this embodiment, the extreme value is the maximum value. As shown in FIG. 7, the magnitude of the power increases as the phase θ increases, and after reaching the maximum value M2, it tends to decrease. When the phase θ with respect to the position of the rotor approaches the optimum value, the power factor improves and the loss of the system decreases. As a result, the magnitude of the power approaches the maximum value M2. In other words, when the magnitude of the power becomes the maximum value M2, it is assumed that the phase θ is at the optimum value.

[0060] When the power increases, the correction unit 64 maintains the correction direction, and when the power decreases, the correction unit 64 reverses the correction direction. Specifically, as a result of correcting in the direction of increasing the phase θ (the first direction), if the power increases, the correction unit 64 corrects in the direction of increasing the phase θ again. As a result of correcting in the direction of increasing the phase θ, if the power decreases, the correction unit 64 corrects in the direction of decreasing the phase θ (the second direction opposite to the first direction).

[0061] As a result of correcting in the direction of decreasing the phase θ, if the power increases, the correction unit 64 corrects in the direction of decreasing the phase θ again. As a result of correcting in the direction of decreasing the phase θ, if the power decreases, the correction unit 64 corrects in the direction of increasing the phase θ. In this way, the correction unit 64 increases and decreases the phase θ so that the magnitude of the power approaches the maximum value M2. The correction unit 64 performs feedback control on the phase θ based on the change in power.

[0062] Next, the process executed in the control device 6A will be described. As shown in FIG. 8, the process executed by the control device 6C of the electromechanical system 1C is different in that it has step S51 instead of step S5. Other configurations of the process of the electromechanical system 1C are the same as those of the process of the electromechanical system 1A. In step S51, the correction unit 64 determines whether the power is greater than the reference value.

[0063] According to the electromechanical system 1C, similar to the electromechanical system 1A, the performance can be improved by optimizing the phase θ.

[0064] [Modification Example] Although the embodiments have been described above, the present disclosure is not limited to the above-described embodiments.

[0065] In the first embodiment, an example in which step S2 is executed after step S1 has been shown. However, as shown in FIG. 9, step S2 may be executed after step S6. Specifically, when the result of step S1 is YES, step S3 is executed. After step S6 is executed, step S2 is executed. After step S2 is executed, step S1 is executed again.

[0066] In the first embodiment, an example in which the position of the rotor is detected by a resolver has been shown. However, the position of the rotor may be detected by, for example, a hall sensor. The position of the rotor may be estimated. For detecting and estimating the position of the rotor, various known methods may be used.

[0067] In the first embodiment, an example in which the power supply 3 is a DC power supply has been shown. However, the power supply 3 may be an AC power supply. In this case, the AC power output from the power supply 3 is rectified into DC power and then input to the drive device 4A.

[0068] In the second embodiment, an example in which the power Pi is calculated based on the current Im has been shown. However, the power Pi may be calculated based on table data or the like. Also, Pm may be calculated as an effective value from the detected value. When vector control is applied, Pm may be calculated on the dq coordinates. For calculating Pm, various known methods may be used.

[0069] In the second embodiment, an example in which the control unit 60 has the arithmetic unit 66 has been shown. However, the control unit 60 may not have the arithmetic unit 66. In this case, the correction unit 64 corrects the phase θ based on the signal regarding Pm transmitted from the power detection unit 65. That is, the correction unit 64 may correct the phase θ based on the power output from the drive device 4B.

[0070] In each embodiment, an example was shown in which the correction unit 64 calculates power based on voltage and current and corrects the phase θ so that the magnitude of the power approaches an extreme value. However, the correction unit 64 may correct the phase θ so that the magnitude of the current approaches an extreme value. In the electromechanical systems 1A and 1B, the phase θ at which the power becomes the minimum value M1 (see FIG. 3) and the phase θ at which the current becomes the minimum value coincide. In the electromechanical system 1C, the phase θ at which the power becomes the maximum value M2 (see FIG. 7) and the phase θ at which the current becomes the maximum value coincide. Therefore, when the magnitude of the current approaches an extreme value, the magnitude of the power also approaches an extreme value. The current may be calculated as an effective value from, for example, a detected value (instantaneous value). When vector control is applied, the current may be calculated on the dq coordinates.

[0071] [Fourth Embodiment] A control example based on a signal from the power detection unit 65 provided in the electromechanical system 1D will be described. As shown in FIG. 10, the electromechanical system 1D according to the fourth embodiment mainly differs from the electromechanical system 1B of the second embodiment in that it includes a drive device 4D instead of the drive device 4B. The drive device 4D mainly differs from the drive device 4B of the second embodiment in that it has a control device 6D instead of the control device 6B. Other configurations of the electromechanical system 1D are the same as those of the electromechanical system 1B. Hereinafter, differences between the electromechanical system 1D and the electromechanical system 1B will be described.

[0072] In the present embodiment, the control unit 60 of the control device 6D corrects the phase θ based on a signal regarding the power Pm transmitted from the power detection unit 65. The correction unit 64 of the control unit 60 corrects the phase θ so that the power Pm output from the drive device 4D approaches an extreme value. When correcting the phase θ, the correction unit 64 does not have to consider the power consumed by the power converter 5. According to the electromechanical system 1D, as with the electromechanical system 1B, the performance can be improved by optimizing the phase θ.

[0073] [Fifth Embodiment] As shown in FIG. 11, the electromechanical system 1E according to the fifth embodiment mainly differs from the electromechanical system 1A of the first embodiment in that it includes a drive device 4E instead of the drive device 4A. The drive device 4E mainly differs from the drive device 4A of the first embodiment in that it has a control device 6E instead of the control device 6A. Other configurations of the electromechanical system 1E are the same as those of the electromechanical system 1A. Hereinafter, differences between the electromechanical system 1E and the electromechanical system 1A will be described.

[0074] The electromechanical device 2 of the electromechanical system 1E has a stator 21 and a rotor 22 rotatable with respect to the stator 21, similar to the electromechanical device 2 of the electromechanical system 1A. The stator 21 includes a coil 23. The rotor 22 includes a magnet 24.

[0075] The control device 6E further includes a speed estimation unit 67 and a current detection unit 68. The speed estimation unit 67 estimates the rotational speed ωr of the electromechanical device 2. The rotational speed ωr is detected by, for example, a magnetic pole position sensor (e.g., resolver), a rotational speed sensor, or the like. The rotational speed ωr may be an estimated value applied to, for example, sensorless control of the magnetic pole position. The speed estimation unit 67 transmits a signal related to the rotational speed ωr to the correction unit 64.

[0076] The current detection unit 68 is connected between the power converter 5 and the electromechanical device 2. The current detection unit 68 detects the alternating current Ia output from the power converter 5. The alternating current Ia may be calculated as an effective value or an absolute average value from, for example, a detected value (instantaneous value). When vector control is applied, the current may be calculated in the dq coordinate system. The current detection unit 68 transmits a signal related to the alternating current Ia to the correction unit 64.

[0077] The correction unit 64 calculates an index value based on the signal related to the voltage V transmitted from the voltage detection unit 61, the signal related to the current I transmitted from the current detection unit 62, the signal related to the rotational speed ωr transmitted from the speed estimation unit 67, and the signal related to the alternating current Ia transmitted from the current detection unit 68.

[0078] The index value is correlated with the current input to the coil of the electromechanical machine 2. The larger the magnitude of the current input to the coil of the electromechanical machine 2, the larger the index value. In the present embodiment, the index value is a division value obtained by dividing the current Ia (the current input to the coil of the electromechanical machine 2) by the torque of the electromechanical machine 2. Let the torque of the electromechanical machine 2 be T, the voltage input to the power converter 5 (the DC voltage output from the power supply 3) be V, the current input to the power converter 5 (the DC current output from the power supply 3) be I, the alternating current input to the electromechanical machine 2 be Ia, and the rotational speed of the electromechanical machine 2 be ωr. Then, the torque of the electromechanical machine 2 is calculated by the formula T = (V×I - K×Ia) / ωr. Here, K is a loss coefficient calculated based on the connection between the power converter 5 and the electromechanical machine 2. The correction unit 64 corrects the phase θ so that the index value tends toward an extreme value. In the present embodiment, the index value is the minimum value.

[0079] As described above, in the electromechanical system 1E, the correction unit 64 corrects the phase θ of the signal so that the index value correlated with the current input to the coil tends toward an extreme value. When the index value correlated with the current input to the coil reaches an extreme value, it is assumed that the loss of the electromechanical machine 2 is minimized, that is, the phase θ of the signal with respect to the position of the rotor is optimal. Thereby, even without detecting the position of the rotor with high precision, it is possible to suppress the consumption of wasted power by optimizing the phase θ of the signal. Therefore, according to the electromechanical system 1E, the performance can be improved.

[0080] The index value is a division value obtained by dividing the current Ia input to the coil by the torque of the electromechanical device 2. As a result, the change amount of the index value per change amount of the phase θ becomes relatively large, so that the control of the phase θ can be performed with higher sensitivity. Specifically, as shown in FIG. 12, the change amount of the index value per change amount of the phase θ (see the solid line G1 in FIG. 12) is larger than the change amount of the power per change amount of the phase θ (see the dotted line G2 in FIG. 12). Thereby, since the minimum value (extreme value) M1 becomes more prominent, the phase θ can be corrected with higher sensitivity so that the index value approaches the minimum value M1. Further, since the torque of the electromechanical device 2 is calculated by the above-described formula, for example, compared with the case where it is detected by a sensor or the like, the configuration of the device is simplified, so that the cost can be reduced.

[0081] The index value may be the current input to the coil of the electromechanical device 2. The index value may be a multiplication value obtained by multiplying the alternating current input to the coil of the electromechanical device 2 by the alternating voltage input to the coil of the electromechanical device 2. The index value may be the temperature of the coil of the electromechanical device 2. The temperature of the coil of the electromechanical device 2 is, for example, a measured value by a thermometer. The temperature of the coil of the electromechanical device 2 is correlated with the current input to the coil of the electromechanical device 2. The higher the magnitude of the current input to the coil, the higher the temperature of the coil. The index value may be a division value obtained by dividing the temperature of the coil of the electromechanical device 2 by the torque of the electromechanical device 2. The index value may be the power input to the coil of the electromechanical device 2. The index value only needs to be correlated with the current input to the coil of the electromechanical device 2. In these cases, by using various values as the index value, the performance of the electromechanical system can be improved.

[0082] The torque of the electromechanical device 2 may be calculated based on the output of the electromechanical device 2. The torque of the electromechanical device 2 may be detected by a sensor.

[0083] The electromechanical systems 1D and 1E may include the electromechanical device 7 of the third embodiment instead of the electromechanical device 2. The electromechanical systems 1D and 1E may include the load 8 of the third embodiment instead of the power source 3. In this case, the power converter 5 inputs the power output from the electromechanical device 7 to the load 8, similar to the third embodiment. In this case, the index value is correlated with the current output from the electromechanical device 7. The extreme value is the maximum value. The correction unit 64 corrects the phase θ so that the index value heads toward the maximum value.

[0084] The electromechanical system of the present disclosure is "[1] An electromechanical system comprising: an electromechanical device having a stator including a coil and a rotor including a magnet and rotatable with respect to the stator; a power converter for inputting and outputting power to and from the coil; and a control unit for controlling the power converter, wherein the control unit has an output unit for outputting a signal for operating the power converter to the power converter, and a correction unit for correcting the phase of the signal for determining the timing of the input and output of the power to and from the coil, and the correction unit corrects the phase so that the magnitude of the power heads toward an extreme value."

[0085] The electromechanical system of the present disclosure may be "[2] The electromechanical device is an electric motor, the extreme value is a minimum value, and when the power becomes smaller as a result of correcting the phase in the first direction, the correction unit corrects the phase in the first direction again, and when the power becomes larger as a result of correcting the phase in the first direction, the correction unit corrects the phase in a second direction opposite to the first direction, the electromechanical system according to [1] above."

[0086] The electromechanical system of the present disclosure may be "[3] When the phase becomes larger than the maximum limit value as a result of correcting the phase, the correction unit sets the maximum limit value as the corrected phase, and when the phase becomes smaller than the minimum limit value as a result of correcting the phase, the correction unit sets the minimum limit value as the corrected phase, the electromechanical system according to [1] or [2] above."

[0087] The electromechanical system of the present disclosure may be the one described in any one of [1] to [3] above, "wherein the correction unit includes an execution mode for performing the phase correction and a pause mode for pausing the phase correction."

[0088] The electromechanical system of the present disclosure may be the one described in [1] above, "wherein the electromechanical machine is a generator, the extreme value is a maximum value, and when the power increases as a result of correcting the phase in the first direction, the correction unit corrects the phase in the first direction again, and when the power decreases as a result of correcting the phase in the first direction, the correction unit corrects the phase in a second direction opposite to the first direction."

[0089] The electromechanical system of the present disclosure is an electromechanical system including "a stator including a coil, a rotor including a magnet and rotatable with respect to the stator, an electromechanical machine having the same, a power converter for inputting and outputting power to and from the coil, and a control unit for controlling the power converter, wherein the control unit has an output unit for outputting a signal for operating the power converter to the power converter and a correction unit for correcting the phase of the signal for determining the timing of the input and output of the power to and from the coil, and the correction unit corrects the phase so that an index value correlated with the current input to and output from the coil approaches an extreme value."

[0090] The electromechanical system of the present disclosure may be the one described in [6] above, "wherein the index value is a division value obtained by dividing the current by the torque of the electromechanical machine."

[0091] The electromechanical system of the present disclosure may be the one described in [6] above, "wherein the index value is the current."

[0092] The electromechanical system of the present disclosure may be the one described in [6] above, where "the index value is a multiplication value obtained by multiplying the AC voltage input to and output from the coil by the AC current input to and output from the coil."

Explanation of reference numerals

[0093] 1A, 1B, 1C, 1D, 1E Electromechanical system 2, 7 Electromechanical machine 5 Power converter 60 Control unit 63 Output unit 64 Correction unit θ Phase

Claims

1. A generator having a stator including a coil and a rotor including a magnet and rotatable with respect to the stator, a power converter for inputting and outputting power to and from the coil, and a control unit for controlling the power converter, wherein the control unit has an output unit that outputs a signal for operating the power converter to the power converter, and a correction unit that corrects the phase of the signal that determines the timing of the input and output of the power to the coil, wherein the phase is the timing at which the signal is output to the power converter with respect to the angle by which the rotor rotates with respect to the stator, the correction unit corrects the phase so that the magnitude of the power tends toward a maximum value, the correction unit corrects the phase in the first direction again when the power increases as a result of correcting the phase in the first direction, and corrects the phase in a second direction opposite to the first direction when the power decreases as a result of correcting the phase in the first direction, an electromechanical system.

2. The electromechanical system according to claim 1, wherein when the phase becomes greater than a maximum limit value as a result of correcting the phase, the correction unit sets the maximum limit value as the corrected phase, and when the phase becomes smaller than a minimum limit value as a result of correcting the phase, the correction unit sets the minimum limit value as the corrected phase.

3. The electromechanical system according to claim 1, wherein the correction unit includes an execution mode for executing the correction of the phase and a pause mode for pausing the correction of the phase.

4. An electromechanical device having a stator including a coil and a rotor including a magnet and rotatable with respect to the stator, a power converter for inputting and outputting power to and from the coil, and a control unit for controlling the power converter, wherein the control unit has an output unit that outputs a signal for operating the power converter to the power converter, and a correction unit that corrects the phase of the signal that determines the timing of the input and output of the power to the coil, wherein the correction unit corrects the phase so that an index value correlated with the current input to and output from the coil tends toward an extreme value, and the index value is a division value obtained by dividing the current by the torque of the electromechanical device, an electromechanical system.

5. The electromechanical system according to claim 4, wherein the index value is the current.

6. The electromechanical system according to claim 4, wherein the index value is a multiplication value obtained by multiplying an alternating current input to and output from the coil by an alternating voltage input to and output from the coil.

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