JP5994631B2 - Rotating electrical machine - Google Patents

Description

  The present invention relates to a so-called synchronous electric rotating machine.

  Conventionally, a synchronous rotary electric machine (for example, a motor) is driven by controlling an output voltage of a power converter such as an inverter. For such rotating electrical machines, the so-called trip is prevented by setting the upper limit value of the current phase at or near the current phase that maximizes the motor torque in the inverter output voltage at each moment. There are some which are controlled so as to do (see, for example, Patent Document 1).

Japanese Patent No. 3622666

  By the way, the torque curve of the synchronous rotating electrical machine (here, a curve in which the value of the output torque with respect to the current phase is plotted) is an upwardly convex curve. For example, tripping can be prevented by setting the upper limit value so that the current phase does not advance beyond the inflection point (peak) of the torque curve at the time of overload.

  However, the rotary electric machine may require high speed operation in a situation where the load is relatively small (referred to as light load) in applications where power running operation and regenerative operation are repeated, and in the upper limit setting as described above, There are cases where high speed operation is not possible with light loads. This is because, as the load is smaller, the inflection point of the torque curve tends to shift to a region where the current phase is larger, and depending on the capacity of the rotating electrical machine, the region where the torque curve exceeds the upper limit at light load This is because the vehicle may enter the vehicle (that is, when driving is restricted). On the other hand, increasing the output of the rotating electrical machine enables high-speed operation at a light load, but there is a concern about an increase in cost and device scale.

  The present invention has been made paying attention to the above problems, and is intended to enable operation even at light loads while preventing tripping by limiting the current phase without increasing the output of the rotating electrical machine. It is aimed.

In order to solve the above-mentioned problem, the first invention
In the rotating electrical machine connected to the power converter (20) and in which the rotation of the rotor and the rotating magnetic field of the stator are synchronized,
The output of the power converter (20) is limited according to the magnitude of the current phase of the current that flows to form the rotating magnetic field, the output torque is equal to or less than a predetermined torque threshold, and the rotation speed is predetermined. A control unit (28) for controlling the power converter (20) so that the current phase advances in comparison with a current phase when generating a maximum torque at the maximum load in a high-speed light load state equal to or higher than a rotation speed threshold value of It is characterized by having.

  In this configuration, the rotating electrical machine is operated without limiting the current phase in the high-speed light load state.

In addition, the second invention,
In the rotary electric machine of the first invention,
The control unit (28) is configured to be able to control the output of the power converter (20) so that the current phase is equal to or less than a predetermined current phase limit (Li), and in the case of the high-speed light load state, The current phase limit (Li) is increased or the control using the current phase limit (Li) is canceled.

  In this configuration, the current phase limit (Li) is changed or the control using the current phase limit (Li) is released, and the rotating electrical machine is operated without the current phase being limited in a high-speed light load state.

In addition, the third invention,
In the rotary electric machine of the first invention,
The control unit (28) generates a d-axis current command for instructing a d-axis current value and a q-axis current command for instructing a q-axis current value based on an output torque, and in the case of the high-speed light load state, Corrects the d-axis current command to increase the d-axis current.

  In this configuration, the current phase is advanced by increasing the d-axis current by correcting the d-axis current command.

In addition, the fourth invention is
In the rotating electrical machine of the third invention,
The control unit (28) obtains a d-axis current value and a q-axis current value determined based on the output torque, and multiplies the d-axis current value by a predetermined gain to generate the d-axis current command. The q-axis current command is generated by multiplying the axis current value by a predetermined gain, and the obtained d-axis current value is increased so that the flowing d-axis current value increases in the high-speed light load state. At least one of a gain to be multiplied and a gain to be multiplied by the obtained q-axis current value is corrected.

  In this configuration, the d-axis current value is increased and the current phase is advanced by correcting at least one of the gain multiplied by the d-axis current value and the gain multiplied by the q-axis current value.

In addition, the fifth invention,
In the rotating electric machine according to any one of the first to fourth inventions,
The control unit (28) determines whether or not the high-speed and light load state is established, the relationship between the voltage phase magnitude of the voltage for forming the rotating magnetic field and the magnitude of the current phase, and the rotating magnetic field. Judgment is made using at least one of the values of the current flowing in the current.

  According to the first invention, it is possible to operate even in a high-speed light load state while preventing tripping by limiting the current phase without increasing the output.

  Further, according to the second invention, it is possible to easily switch whether or not the current phase is limited.

  Further, according to the third and fourth inventions, the current phase can be advanced with a simple configuration, and the operation in the high speed and light load state can be easily performed.

  Further, according to the fifth aspect, it is possible to determine whether or not the vehicle is in a high-speed and light load state based on parameters that can be obtained by a conventional device.

FIG. 1 is a diagram illustrating a configuration of the refrigeration apparatus according to the first embodiment. FIG. 2 shows the configuration of the control unit of the first embodiment. FIG. 3 shows the torque curve of the motor. FIG. 4 is a flowchart for explaining the operation of the control unit according to the first embodiment. FIG. 5 shows a voltage limit ellipse in an intermediate load state. FIG. 6 shows an example of an operating area in the refrigeration apparatus and an operating point in an intermediate load state. FIG. 7 shows the voltage limit ellipse in the high speed heavy load state. FIG. 8 shows an example of the operating point in the high speed heavy load state. FIG. 9 shows a voltage limit ellipse in the high speed light load state. FIG. 10 shows an example of the operating point in the high speed light load state. FIG. 11 shows the configuration of the control unit of the second embodiment. FIG. 12 shows the configuration of the current phase limiter and the dq-axis current command generator in the second embodiment. FIG. 13 is a flowchart for explaining the operation of the control unit according to the second embodiment. FIG. 14 illustrates a configuration of a control unit according to the third embodiment. FIG. 15 illustrates a configuration of a current phase limit unit and a dq-axis current command generation unit according to the third embodiment. FIG. 16 is a flowchart for explaining the operation of the control unit according to the third embodiment. FIG. 17 shows the configuration of the control unit of the fourth embodiment. FIG. 18 illustrates a configuration of a current phase limit unit and a dq-axis current command generation unit according to the fourth embodiment. FIG. 19 is a flowchart for explaining the operation of the control unit according to the fourth embodiment. FIG. 20 shows an example of a voltage limit ellipse.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following embodiments are essentially preferable examples, and are not intended to limit the scope of the present invention, its application, or its use.

Embodiment 1 of the Invention
FIG. 1 is a diagram showing a configuration of a refrigeration apparatus (1) according to Embodiment 1 of the present invention. As shown in FIG. 1, the refrigeration apparatus (1) includes a refrigerant circuit (10), a power conversion device (20), a power regeneration converter circuit (25), and a control unit (28).

<Configuration of refrigerant circuit (10)>
The refrigerant circuit (10) includes a compressor (11), a condenser (12), an expander (13), and an evaporator (14), which are connected by a refrigerant pipe. In the refrigerant circuit (10), the refrigerant is circulated to perform a refrigeration cycle.

  For the compressor (11), various types of compression mechanisms such as a scroll compressor can be employed. The compressor (11) is driven by a motor (11a). The motor (11a) is a synchronous motor. The synchronous motor is one of rotating electric machines in which the rotation of the rotor and the rotating magnetic field of the stator are synchronized. As the motor (11a) of the present embodiment, for example, an embedded magnet (so-called IPM: Interior Permanent Magnet) type motor is employed. The motor (11a) is an example of the rotating electric machine of the present invention.

  The condenser (12) and the evaporator (14) are so-called air heat exchangers that exchange heat between air and refrigerant, and for example, a cross fin and tube heat exchanger can be adopted.

  The expander (13) expands the refrigerant that has flowed in to generate power. For example, although not shown, the expander (13) can be constituted by a so-called oscillating piston type rotary fluid machine. In the rotary fluid machine, a cylinder and a piston are provided, the piston is driven by the expansion energy of the refrigerant that has flowed in, and the output shaft (not shown) is driven to rotate. A generator (26) is connected to the output shaft, and is rotated by the power of the expander (13). In the present embodiment, the generator (26) employs an embedded magnet type generator (hereinafter also referred to as an IPM generator) in which a magnet is embedded in the core of the rotor.

<Configuration of power converter (20)>
As shown in FIG. 1, the power conversion device (20) includes a converter circuit (21), a DC link unit (22), and an inverter circuit (23).

  In the power conversion device (20), the three-phase AC input from the AC power source (40) is input to the converter circuit (21). The converter circuit (21) is composed of, for example, a diode bridge circuit and rectifies alternating current. The DC link unit (22) includes an electrolytic capacitor, and the electrolytic capacitor smoothes the output of the converter circuit (21). The smoothed direct current is input to the inverter circuit (23). The inverter circuit (23) includes a plurality of (for example, six) switching elements that are bridge-connected, and these switching elements switch input direct current to convert it into alternating current. In the inverter circuit (23), a rectangular wave drive of the switching element is performed by PWM control. The output (AC power) of the inverter circuit (23) is supplied to the motor (11a).

<Power regeneration converter circuit (25)>
The power regeneration converter circuit (25) includes a plurality of (for example, six) switching elements connected in a bridge, and the switching elements convert the output (AC power) of the generator (26) to DC. ing.

<Control unit (28)>
A control part (28) is comprised, for example with a microcomputer, and controls on-off of the switching element of the inverter circuit (23) of a power converter device (20) and a power regeneration converter circuit (25). The control unit (28) controls the inverter circuit (23) so that the current phase of the motor (11a) does not exceed a predetermined threshold value (hereinafter referred to as current phase limit (Li) or upper limit set value). Controls switching in the inverter circuit (23). Details of the control will be described later. Here, the current phase is a phase of a current that is passed through a stator coil (not shown) to form the rotating magnetic field in the motor (11a), and the voltage phase is a voltage phase in that case. . More specifically, the current phase is an angle formed by the d-axis and the armature current vector when the synchronous rotary electric machine is represented by a so-called dq-axis model.

  FIG. 2 shows a configuration of the control unit (28) of the first embodiment. As shown in FIG. 2, the control unit (28) includes a PWM modulation unit (51), a flux weakening request unit (52), a high-speed light load determination unit (53), a current phase command generation unit (54), a selector (55 ), Current phase controller (56), command speed calculator (57), position / speed detector (58), speed controller (59), dq-axis current command generator (60), and current controller (61) ).

  The PWM modulation unit (51) receives a voltage command for instructing an output voltage and a voltage phase command for instructing a voltage phase, and turns on each switching element of the inverter circuit (23) in accordance with these commands. A time (duty) is determined, and a signal for driving the switching element is output to the inverter circuit (23) according to the determined duty.

  The flux weakening requesting unit (52) uses the current duty information and the current rotational speed information of the motor (11a) to determine whether or not so-called weakening magnetic flux control needs to be performed, and to weaken the magnetic flux. When it is necessary to perform control, the current value in that case is obtained.

  The high speed light load determination unit (53) determines whether or not the rotation speed of the motor (11a) is higher than a predetermined value and the load is smaller than a predetermined value (referred to as a high speed light load state for convenience of explanation). to decide. Although various methods can be adopted for this determination, in the present embodiment, the high-speed light load determination unit (53) determines whether or not there is a high-speed light load from the relationship between the current phase and the voltage phase. Specifically, the high-speed light load determination unit (53) determines that the voltage phase is behind the current phase when the voltage phase is behind the current phase, and when the voltage phase is ahead of the current phase. It is determined that the load is not high-speed and light (referred to as high load for convenience of explanation). The determination result is output to the selector (55).

  The current phase command generation unit (54) includes a current phase command generation unit (54a) and an upper limit value determination unit (54b). The current phase command generation unit (54a) obtains a current phase when it is necessary to perform flux-weakening control, and generates a current phase command (which may be considered as a current phase value) that indicates the obtained current phase. The upper limit determination unit (54b) determines whether the current phase obtained by the current phase command generation unit (54a) exceeds the current phase limit (Li), and switches the output destination of the current phase command according to the determination result. . Specifically, the upper limit value determination unit (54b) outputs a current phase command to the dq axis current command generation unit (60) when the current phase does not reach the current phase limit (Li), and the current phase limit When (Li) is reached, control is performed so that the current phase command is output to the selector (55).

  The selector (55) switches the output destination of the current phase command according to the determination result of the high speed / light load determination unit (53). Specifically, the selector (55) outputs the input current phase command to the current phase limit changing unit (561) described later when the determination result is a high speed light load, and when the determination result is not a high speed light load, The current is output to a current phase limiter (562) described later.

  The current phase control unit (56) includes a current phase limit change unit (561) and a current phase limit unit (562). When the current phase command is input via the selector (55), the current phase limit changing unit (561) corrects the current phase command to a larger value and outputs the corrected value to the dq-axis current command generation unit (60). The current phase limit unit (562) limits the input current phase command to the current phase limit (Li) or less and outputs it to the dq axis current command generation unit (60). When the current phase limit (Li) is exceeded, a speed droop request (command for instructing speed reduction) is output to the command speed calculation unit (57).

  The command speed calculation unit (57) determines a target rotation speed of the motor (11a) and outputs a speed command for instructing the rotation speed to the speed control unit (59).

  The position / speed detection unit (58) receives information on the terminal voltage of the motor (11a) and the motor current (three-phase current value) to determine the position of the rotor of the motor (11a) and the current rotation speed. It has become.

  The speed control unit (59) obtains a difference between the speed command and the current rotation speed, and outputs a torque command for instructing a torque to be generated according to the difference to the dq-axis current command generation unit (60).

  The dq-axis current command generation unit (60) obtains a current value (a magnitude of a current vector) that flows to the motor (11a) from the torque command and the current rotor position, and the current phase is designated by the current phase command. A d-axis current command (id current command in FIG. 2 and the like) for instructing the d-axis current and a q-axis current command (iq current command in FIG. 2 and the like) instructing the q-axis current are generated so as to be a value. .

  The current control unit (61) determines the difference between the current d-axis current value and the d-axis current command, and the difference between the q-axis current value and the q-axis current command, and determines the output voltage of the inverter circuit (23). To do. The current control unit (61) outputs the determined output voltage information (voltage command) and the voltage phase information (voltage phase command) to the PWM modulation unit (51).

<Operation of motor in this embodiment>
In the refrigeration system (1), a compressor (11), a condenser (12), an expander (13), and an evaporator (14) are connected to a closed circuit in order by refrigerant piping to form a refrigerant circuit (10). It is. If cooling operation is performed in the refrigeration system (1), the refrigerant is sent from the compressor (11) to the condenser (12), and the condenser (12) exchanges heat with the outside air to dissipate heat. Then, while adjusting the flow rate and pressure of the refrigerant with the expander (13), the evaporator (14) exchanges heat with the room air to absorb heat, and repeatedly returns it to the compressor (11) as a gas refrigerant. In such operation, the rotation speed and output torque of the motor (11a) are appropriately controlled by the control unit (28) according to the required cooling capacity.

  FIG. 3 illustrates a torque curve of the motor (11a) (here, a curve plotting the value of the output torque against the current phase). Each torque curve (T1, T2, T3, T4) shows characteristics under different load conditions. As shown in the figure, the torque curves (T1, T2, T3, T4) are upwardly convex curves. For example, the torque curve (T1) is a torque curve at the maximum load in the refrigeration apparatus (1), and the current phase limit determined from the peak of the torque curve (T1) is Li1.

  In the present embodiment, the current phase limit (Li) is varied by the control unit (28). FIG. 4 is a flowchart illustrating the operation of the control unit (28) in the first embodiment. First, in step S11, the current phase command generation unit (54) determines whether or not the current phase has reached the current phase limit (Li). If the result of the determination is No, the process proceeds to step S12.

  The process proceeds to step S12 in the case of an intermediate load state in the refrigeration apparatus (1), for example. FIG. 5 shows a voltage limit ellipse in an intermediate load state. Here, the voltage limit ellipse is an output range of a current vector that can be operated under the restriction of the rotation speed of the motor and the voltage that can be output from the inverter circuit, and FIG. The horizontal axis is the d-axis current. The motor (11a) can be operated when the end of the current vector is within the voltage limit ellipse (including the ellipse).

  FIG. 6 shows an example of the operation area in the refrigeration apparatus (1) and the operating point in the intermediate load state. In FIG. 6, the vertical axis represents the torque of the motor (11a), the horizontal axis of the motor (11a) represents the rotational speed, and the motor (11a) is within the area surrounded by the straight line (A, B, C) and the coordinate axis. You can drive.

  Then, as shown in FIG. 6, when the operating point of the motor (11a) is approximately at the center of the operating area, the intermediate load state is established. In the intermediate load state, the current phase limit (Li) is set to a current phase near the maximum output at the maximum rotation speed of the motor (11a). That is, at this time, the current phase limit (Li) is the above-described current phase limit (Li1). The broken line in FIG. 5 indicates the direction of a current vector whose current phase is the same value as the current phase limit (Li1) (referred to as the maximum phase current vector for convenience of explanation). In order to operate the motor (11a) under the current phase limit (Li) limit in the example of FIG. 5, the end of the current vector is placed in the area within the voltage limit ellipse and above the broken line. Need to control.

  Returning to FIG. 4, in step S12, the current phase command generator (54) outputs the current phase command to the dq-axis current command generator (60). Thus, in the refrigeration apparatus (1), the motor (11a) is operated at the current target rotational speed.

  On the other hand, if the determination result in step S11 is Yes, the process proceeds to step S13. At this time, the current phase command generator (54) outputs the current phase command to the selector (55).

  In step S13, the high speed / light load determination unit (53) determines whether or not the state is a high speed / light load. If the result of the determination is No, the process proceeds to step S14. At this time, the selector (55) switches the output destination to the current phase limit unit (562).

  Proceeding to step S14 is a state in which high-speed operation is performed in a high load state in the refrigeration apparatus (1) (hereinafter referred to as a high-speed heavy load state). FIG. 7 shows the voltage limit ellipse in the high speed heavy load state. FIG. 8 shows an example of operating points in a high speed heavy load state. In the high speed heavy load state, the current phase limit (Li) is set to a current phase that is close to the maximum output at the maximum rotation speed of the motor (11a). That is, at this time, the current phase limit (Li) is the above-described current phase limit (Li1).

  The current phase limit unit (562) limits the input current phase command to the current phase limit (Li) or less and outputs it to the dq-axis current command generation unit (60), and outputs the speed droop request to the command speed calculation unit. Output to (57). The command speed calculation unit (57) outputs a speed command for instructing a rotation speed lower than the original target value to the speed control unit (59) (step S15). As a result, the motor (11a) is operated at a rotational speed lower than the current target rotational speed.

  On the other hand, if “Yes” is determined in step S13, the state is a high-speed light load state, and the process of step S16 is performed. In the state of high speed and light load, the output destination of the selector (55) is switched to the current phase limit changing unit (561).

  FIG. 9 shows a voltage limit ellipse in the high speed light load state. FIG. 10 shows an example of operating points in a high-speed light load state. In the high-speed light load state, if the current phase limit (Li) is set to the current phase that is close to the maximum output at the maximum rotation speed of the motor (11a) (that is, the current phase limit (Li1)), the current vector will be on the voltage limit ellipse. Even in this case, driving is restricted.

  When the characteristics of the motor (11a) in the high speed and light load state are seen in FIG. 3, it corresponds to the torque curve (T4) having the lowest peak. The torque curve (T4) is included on the right side of the current phase limit (Li1) (range beyond the current phase limit (Li1)). Therefore, in the conventional control method, a trip state occurs when attempting to operate in this region. However, in the present embodiment, the current phase limit changing unit (561) changes the current phase limit (Li) to a value larger than the current value. Specifically, the current phase value near the peak of the torque curve (T4) at high speed and low load is set as a new current phase limit (Li4). When the current phase obtained by the current phase command generation unit (54) is smaller than the new current phase limit (Li4), the current phase limit changing unit (561) converts the input current phase command to the dq axis. Output to the current command generator (60).

  Thereby, in the refrigeration apparatus (1), if the current vector is within the voltage limit ellipse, it is possible to operate with the current phase obtained by the current phase command generation unit (54). That is, the current phase command is controlled to be more advanced, the flux weakening control is performed, and the speed drooping (deceleration) is not performed (step S17).

<Effect in this embodiment>
As described above, in the present embodiment, the current phase limit (Li) is appropriately changed according to the rotation speed and the load, and the operation in the high speed and light load state becomes possible. In addition, the current phase can be appropriately limited, and tripping can be prevented.

  The current phase limit changing unit (561) is configured to unconditionally output the input current phase command to the dq axis current command generation unit (60), that is, to cancel the current phase limit (Li) control. May be.

<< Embodiment 2 of the Invention >>
Embodiment 2 of the invention describes another example of current phase limit control. In the present embodiment, the d-axis current is increased by correcting the d-axis current command in the case of the high-speed light load state. FIG. 11 shows the configuration of the control unit (28) of the second embodiment. The controller (28) of the present embodiment differs from that of the first embodiment in the configuration of the current phase controller (56) and the dq-axis current command generator (60). FIG. 12 shows the configuration of the current phase control unit (56) and the dq-axis current command generation unit (60) of the second embodiment.

  As shown in FIG. 12, the current phase control unit (56) includes a current phase limit unit (562) and a d-axis current command addition component calculation unit (563). The function of the current phase limit unit (562) is the same as that of the first embodiment, and the input current phase command is limited to the current phase limit (Li) or less and output to the dq-axis current command generation unit (60). When the value indicated by the current phase command exceeds the current phase limit (Li), the switch (562a) is turned on, and a speed droop request (command for instructing speed reduction) is issued to the command speed calculation unit (57) Output to.

  The d-axis current command addition component calculation unit (563) calculates how much the d-axis current should be increased in order to set the current phase to the value indicated by the current phase command, and the necessary increment (Id command addition) Component). Specifically, the d-axis current command addition component calculation unit (563) obtains a difference between the current phase indicated by the current phase command and the current phase limited by the current phase limit unit (562), and calculates the difference. The Id command addition component is obtained by processing by the PI controller (563a). The d-axis current command addition component calculation unit (563) turns on the switch (563b) in the high-speed light load state, and outputs the obtained Id command addition component to the dq-axis current command generation unit (60).

  The dq-axis current command generator (60) obtains a current value (current vector magnitude) from the current rotor position and torque command, and the d-axis current and the q-axis current are current phases specified by the current phase command. Then, a d-axis current command for instructing the d-axis current and a q-axis current command for instructing the q-axis current are generated. Specifically, the dq-axis current command generation unit (60) uses the current phase (β) output from the current phase limit unit (562), and multiplies the torque command value by −sin (β) to provide a d-axis current value. And the q-axis current value is obtained by multiplying the torque command value by cos (β).

  Then, the dq-axis current command generation unit (60) adds the Id command addition component input from the d-axis current command addition component calculation unit (563) to the generated d-axis current command. Thereby, the d-axis current value becomes a larger value than the magnitude determined from the current phase limited by the current phase limit unit (562). As the d-axis current value increases, the current phase advances.

<Operation of motor in this embodiment>
FIG. 13 is a flowchart illustrating the operation of the control unit (28) in the second embodiment. Steps S21, S22, S23, S24, and S25 correspond to steps S11, S12, S13, S14, and S15 of the first embodiment, respectively. That is, in the case of the intermediate load state or the high speed heavy load state, the same processing as that of the first embodiment is performed.

  On the other hand, the processing in the case of the high speed and light load state is different from that in the first embodiment. In the case of the high speed and light load state, the process of step S26 is performed after passing through steps S21 and S23. First, in step S26, the d-axis current command addition component calculation unit (563) calculates the Id command addition component and outputs it to the dq-axis current command generation unit (60). The dq-axis current command generation unit (60) adds the input Id command addition component to the generated d-axis current command. As a result, the current phase command is controlled to be in a more advanced state, the flux-weakening control is performed, and the speed does not drop (step S27).

  As described above, in the present embodiment, the d-axis current is appropriately corrected according to the rotation speed and the load, and the operation in the high speed and light load state becomes possible. In addition, the current phase can be appropriately limited, and tripping can be prevented.

<< Embodiment 3 of the Invention >>
Another example of the current phase limit control will be described in Embodiment 3 of the invention. FIG. 14 shows the configuration of the control unit (28) of the third embodiment. The controller (28) of the present embodiment differs from that of the first embodiment in the configuration of the current phase controller (56) and the dq-axis current command generator (60). FIG. 15 shows the configuration of the current phase control unit (56) and the dq-axis current command generation unit (60) of the third embodiment.

  As shown in FIG. 15, the current phase control unit (56) includes a current phase limit unit (562) and a d-axis current command generation unit (564). The function of the current phase limit unit (562) is the same as that of the first embodiment, and the input current phase command is limited to the current phase limit (Li) or less and output to the dq-axis current command generation unit (60). When the value indicated by the current phase command exceeds the current phase limit (Li), the switch (562a) is turned on, and a speed droop request (command for instructing speed reduction) is issued to the command speed calculation unit (57) Output to.

  The d-axis current command generation unit (564) calculates the d-axis current based on the current phase command, and multiplies the calculated value by a predetermined gain in the gain multiplication unit (564a) (hereinafter referred to as Id command). ) Is output to the dq-axis current command generator (60).

  The dq-axis current command generation unit (60) obtains a current value (a magnitude of a current vector) that flows to the motor (11a) from the current rotor position and torque command, and the current phase is a value specified by the current phase command. In this manner, a d-axis current command that indicates the d-axis current and a q-axis current command that indicates the q-axis current are generated. Then, the dq-axis current command generation unit (60) outputs the d-axis current command and the q-axis current command obtained by itself to the current control unit (61) when not in the high-speed light load state.

  On the other hand, in the case of the high-speed light load state, the dq-axis current command generation unit (60) outputs the Id command instead of the obtained d-axis current command, and at the same time obtains a predetermined gain to the obtained q-axis current command. Is multiplied by the gain multiplier (62), and is output to the current controller (61) as a new q-axis current command. As a result, the d-axis current becomes a value corresponding to the current phase obtained by the current phase command generator (54). That is, the d-axis current increases. As the d-axis current increases, the current phase advances.

  FIG. 16 is a flowchart illustrating the operation of the control unit (28) in the third embodiment. Steps S31, S32, S33, S34, and S35 correspond to steps S11, S12, S13, S14, and S15 of the first embodiment, respectively. That is, in the case of the intermediate load state or the high speed heavy load state, the same processing as that of the first embodiment is performed.

  On the other hand, the processing in the case of the high speed and light load state is different from that in the first embodiment. In the case of the high speed and light load state, the process of step S36 is performed after passing through steps S31 and S33. First, in step S36, the d-axis current command generation unit (564) calculates the Id command and outputs it to the dq-axis current command generation unit (60). The dq-axis current command generation unit (60) outputs the input Id command to the current control unit (61) instead of the generated d-axis current command. Further, the d-axis current command generation unit (564) outputs a product obtained by multiplying the obtained q-axis current command by a predetermined gain to the current control unit (61) as a new q-axis current command. As a result, the current phase command is controlled to be in a more advanced state, the flux weakening control is performed, and the speed does not drop (step S37).

  As described above, in the present embodiment, the d-axis current is determined according to the rotation speed and the load, and operation in a high speed and light load state is possible. In addition, the current phase can be appropriately limited, and tripping can be prevented.

<< Embodiment 4 of the Invention >>
In the fourth embodiment of the invention, another example of the current phase limit control will be described. FIG. 17 shows the configuration of the control unit (28) of the fourth embodiment. The controller (28) of the present embodiment differs from that of the first embodiment in the configuration of the current phase controller (56) and the dq-axis current command generator (60). FIG. 18 shows the configuration of the current phase control unit (56) and the dq-axis current command generation unit (60) of the fourth embodiment.

  The dq-axis current command generation unit (60) obtains current values (d-axis current value and q-axis current value) that flow to the motor (11a) from the current rotor position and torque command. The dq-axis current command generation unit (60) multiplies the determined d-axis current value by a predetermined gain by the gain multiplication unit (63) to generate a d-axis current command, and multiplies the calculated q-axis current value by gain. The unit (62) is configured to generate a q-axis current command by multiplying a predetermined gain. These gain multipliers (62, 63) are configured so that the gain can be varied.

  As shown in FIG. 18, the current phase control unit (56) includes a current phase limit unit (562) and an Idiq generation gain change unit (565). The function of the current phase limit unit (562) is the same as that of the first embodiment, and the input current phase command is limited to the current phase limit (Li) or less and output to the dq-axis current command generation unit (60). When the value indicated by the current phase command exceeds the current phase limit (Li), the switch (562a) is turned on, and a speed droop request (command for instructing speed reduction) is issued to the command speed calculation unit (57) Output to.

  When the speed droop request is output and in a high-speed light load state, it is necessary to operate with a current phase exceeding the current phase limit (Li1). Therefore, in the control unit (28), when the current phase limit unit (562) outputs the speed droop request, the d-axis current value to be supplied to the motor (11a) is the dq-axis current command generation unit (60). Is larger than the calculated d-axis current value, the gain changing unit (565a) of the Idiq generation gain changing unit (565) adjusts the gain in the gain multiplier (63) and the gain in the gain multiplier (62). . Then, the switch (565b) in FIG. 18 is turned on, and the gain obtained by the gain changing unit (565a) is output to the respective gain multiplying units (62, 63) of the dq-axis current command generating unit (60). Is adjusted. As a result, the d-axis current increases. As the d-axis current increases, the current phase can be advanced.

  FIG. 19 is a flowchart illustrating the operation of the control unit (28) in the fourth embodiment. Steps S41, S42, S43, S44, and S45 correspond to steps S11, S12, S13, S14, and S15 of the first embodiment, respectively. That is, in the case of the intermediate load state or the high speed heavy load state, the same processing as that of the first embodiment is performed.

  On the other hand, the processing in the case of the high speed and light load state is different from that in the first embodiment. In the case of the high speed and light load state, the process of step S46 is performed after passing through steps S41 and S43.

  In step S46, the dq-axis current command generation unit (60) obtains the d-axis current value and the q-axis current value based on the torque command. More specifically, the dq-axis current command generation unit (60) multiplies the torque command value by −sin (β) using the current phase (β) output from the current phase limit unit (562) to generate the d-axis current. A value is obtained, and the q-axis current value is obtained by multiplying the torque command value by cos (β). On the other hand, in the current phase control unit (56), the gain changing unit (565a) calculates a gain by which the d-axis current value and the q-axis current value are multiplied so that the d-axis current value increases. The calculated gain is output to the gain multiplier (62, 63). As a result, the current phase is controlled to be more advanced, and the flux-weakening control is performed, and the speed does not drop (step S47).

  As described above, in the present embodiment, the d-axis current is determined according to the rotation speed and the load, and operation in a high speed and light load state is possible. In addition, the current phase can be appropriately limited, and tripping can be prevented.

  The Idiq generation gain changing unit (565) may be configured to adjust the gain in one of the gain multiplication unit (62) and the gain multiplication unit (63).

<< Other Embodiments >>
<1> The load magnitude determination is not limited to the method of determining from the relationship between the current phase and the voltage phase of the motor. As another example, a voltage limiting ellipse can be used. FIG. 20 shows an example of a voltage limit ellipse. In FIG. 20, the broken line indicates the direction of the aforementioned maximum phase current vector. Here, the current phase limit (Li) is set to a current phase in the vicinity of the maximum output at the maximum rotation speed of the motor (11a).

  In FIG. 20, the current value to be output (the intersection distance means a current value) rather than the shortest distance from the coordinate axis origin to the intersection (P) of the maximum phase current vector and the voltage limit ellipse (intersection distance means a current value). When the magnitude of the current vector is small, the operation of the motor (11a) is limited unless the current phase is advanced beyond the current phase limit (Li). Therefore, the magnitude of the current desired to be output is compared with the intersection distance, and when the magnitude of the current vector is less than the intersection distance, it is determined that the load is light, and the control of the embodiment is performed.

  <2> Further, the load magnitude determination may be performed by adding a current value to the relationship between the voltage phase magnitude and the current phase magnitude. Specifically, when the magnitude of the current vector (current value) is greater than or equal to a preset predetermined value and the voltage vector is ahead of the current phase, it is determined that the load is high, and the magnitude of the current vector is preset. It can be considered that the load is light when the voltage vector is less than the predetermined value and the voltage vector is ahead of the current phase.

  <3> The current phase limit control described in each embodiment can be applied not only to a motor but also to a synchronous generator (for example, the generator (26) in FIG. 1).

  The present invention is useful as a so-called synchronous rotary electric machine.

11a Motor (rotary electric machine)
20 Power Converter 28 Control Unit

Claims (5)

In the rotating electrical machine connected to the power converter (20) and in which the rotation of the rotor and the rotating magnetic field of the stator are synchronized,
The output of the power converter (20) is limited according to the magnitude of the current phase of the current that flows to form the rotating magnetic field, the output torque is equal to or less than a predetermined torque threshold, and the rotation speed is predetermined. A control unit (28) for controlling the power converter (20) so that the current phase advances in comparison with a current phase when generating a maximum torque at the maximum load in a high-speed light load state equal to or higher than a rotation speed threshold value of A rotating electrical machine characterized by comprising. The rotating electrical machine of claim 1,
The control unit (28) is configured to be able to control the output of the power converter (20) so that the current phase is equal to or less than a predetermined current phase limit (Li), and in the case of the high-speed light load state, A rotating electrical machine characterized by increasing a current phase limit (Li) or canceling control using the current phase limit (Li). The rotating electrical machine of claim 1,
The control unit (28) generates a d-axis current command for instructing a d-axis current value and a q-axis current command for instructing a q-axis current value based on an output torque, and in the case of the high-speed light load state, Is a dynamoelectric machine that corrects the d-axis current command to increase the d-axis current. The rotary electric machine according to claim 3,
The control unit (28) obtains a d-axis current value and a q-axis current value determined based on the output torque, and multiplies the d-axis current value by a predetermined gain to generate the d-axis current command. The q-axis current command is generated by multiplying the axis current value by a predetermined gain, and the obtained d-axis current value is increased so that the flowing d-axis current value increases in the high-speed light load state. A rotating electrical machine that corrects at least one of a gain to be multiplied and a gain to be multiplied by a calculated q-axis current value. In the rotary electric machine according to any one of claims 1 to 4,
The control unit (28) determines whether or not the high-speed and light load state is established, the relationship between the voltage phase magnitude of the voltage for forming the rotating magnetic field and the magnitude of the current phase, and the rotating magnetic field. A rotating electric machine characterized in that the determination is made using at least one of the current values to be passed through the motor.

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