JP2013093929A - Controlling device of permanent magnet rotary electric machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a limit value of an output set to prevent demagnetization to be variable and further allows a high output to be obtained in a wider range in a permanent magnet rotary electric machine.SOLUTION: A controlling device of a permanent magnet rotary electric machine is provided with a coil temperature detector 52 for detecting a coil temperature substituted for a temperature of a permanent magnet and a flow rate detector 54 for detecting a flow rate of coolant which is fed to a coil end 28 and performs cooling. An output upper limit setting section 56 sets an output upper limit value on the basis of the coil temperature detected and the flow rate of the coolant detected by referring to a relation between a set of the coil temperature and the flow rate of the coolant and the output upper limit value held beforehand. A controller 36 drive-controls a rotary electric machine 10 within a range not exceeding the output upper limit value set. In response to the flow rate of the coolant, the output upper limit value becomes variable. Accordingly, a high output can be obtained in a wider range.

Description

  The present invention relates to a control device for a permanent magnet rotating electrical machine in which a permanent magnet is disposed on a rotor, and more particularly to control for limiting the output of the rotating electrical machine.

  An electric motor that converts electrical energy into rotational kinetic energy, a generator that converts rotational kinetic energy into electrical energy, and an electric device that functions as both the motor and the generator are known. Hereinafter, these electric devices are referred to as rotating electric machines.

  The rotating electrical machine has two members that are arranged coaxially and relatively rotate. Normally, one is fixed and the other rotates. A coil is arranged on a fixed member (stator), and a rotating magnetic field is formed by supplying electric power to the coil. The other member (rotor) is rotated by the interaction with the magnetic field.

  2. Description of the Related Art There is known a permanent magnet rotating electrical machine in which a permanent magnet is disposed on a rotor and the rotor rotates by the interaction between a rotating magnetic field formed by a stator and the permanent magnet. Permanent magnets can demagnetize, that is, reduce the magnetic flux density. As a cause of demagnetization, temperature and an external magnetic field are known. When an opposite external magnetic field is applied to the permanent magnet with respect to the magnetic flux generated by the permanent magnet, the magnetic flux density of the permanent magnet decreases. If the magnetic flux density of the external magnetic field is small, the magnetic flux density of the permanent magnet returns to the original value if the external magnetic field is removed. However, when the magnetic flux density of the external magnetic field exceeds a certain value, even if the external magnetic field is removed, the magnetic flux density of the permanent magnet does not return to the original value, but becomes a value smaller than the original value. That is, demagnetization occurs.

  Such an upper limit value of the external magnetic field where demagnetization does not occur is called coercive force. That is, demagnetization occurs in the permanent magnet when an external magnetic field greater than this holding force is applied. Moreover, this holding force changes with temperature. For example, it is known that a ferrite magnet has a lower holding power in a low temperature range. In addition, it is known that neodymium magnets have a lower holding power at high temperatures.

  In a permanent magnet rotating electrical machine, when the permanent magnet is demagnetized, the rotating electrical machine cannot exhibit a predetermined performance. Therefore, the permanent magnet rotating electric machine needs to be operated in an area where the demagnetization of the permanent magnet does not occur. For this reason, the output of the rotating electrical machine is suppressed in order to prevent the magnetic flux density of the rotating magnetic field formed by the stator from exceeding the holding force under operating conditions in which the holding force of the permanent magnet decreases and demagnetization occurs. Control may be performed. Patent Document 1 below discloses a technique for detecting the temperature of a permanent magnet and setting an upper limit value of a torque command for a rotating electrical machine so that demagnetization does not occur according to the detected temperature.

JP-A-9-289799

  In a permanent magnet rotating electric machine, a permanent magnet is disposed on a rotor, that is, a rotating member, and it is difficult to directly detect this temperature. Therefore, estimating the temperature of the permanent magnet from the temperature of the other part of the rotating electrical machine, for example, substituting the temperature of the permanent magnet by the temperature of the other part. However, since the temperature of the other part does not necessarily have a one-to-one relationship with the temperature of the permanent magnet, the output upper limit value of the rotating electrical machine is set with a large margin. That is, depending on the conditions, the output limit is excessive, and there is room for setting a higher output upper limit value.

  An object of the present invention is to suppress output limitation corresponding to demagnetization and obtain a high output in a wider region.

  The permanent magnet rotating electrical machine according to the present invention cools the rotating electrical machine by sending a coolant to a predetermined part of the rotating electrical machine. In order to replace the temperature of the permanent magnet, the control device for the permanent magnet rotating electric machine has a temperature detector that detects the temperature of the other part of the rotating electric machine. Moreover, it has a flow rate detector for detecting the flow rate of the coolant. Furthermore, an output upper limit setting unit that sets an output upper limit value of the rotating electrical machine based on the detected temperature and flow rate is provided, and the output is controlled so as to be equal to or less than the set upper limit value, thereby controlling the rotating electrical machine.

  The output upper limit setting unit can set the output upper limit value higher when the detected flow rate is small than when it is high.

  Moreover, the control apparatus of the permanent magnet rotary electric machine of the other aspect of this invention sends a cooling liquid to the predetermined site | part of a rotary electric machine, and cools a rotary electric machine. This control device for a permanent magnet rotating electric machine has a temperature detector for detecting the temperature of other parts of the rotating electric machine in order to estimate the temperature of the permanent magnet. Moreover, it has a flow rate detector for detecting the flow rate of the coolant. The control device has an output upper limit setting unit that sets the output upper limit value of the rotating electrical machine based on the detected temperature, and further outputs the output upper limit value that changes according to the detected coolant flow rate. Has a change part. When the set output upper limit value or the output upper limit value is changed, the rotating electric machine is controlled by limiting the output so as to be equal to or less than the changed output upper limit value.

  By setting the output upper limit value in consideration of the relationship between the temperature of the permanent magnet affected by the flow rate of the coolant and the temperature of the other part of the rotating electrical machine, a higher output can be obtained in a wider range.

It is a schematic block diagram of the rotary electric machine of this embodiment, and its control apparatus. It is a figure which shows the relationship of the temperature of a permanent magnet, coil temperature, and a coolant flow rate. It is a figure which shows the relationship between coil temperature and an output upper limit. It is a figure which shows schematic structure of the apparatus provided with two rotary electric machines.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a permanent magnet rotating electrical machine 10 (hereinafter referred to as a rotating electrical machine 10) and a control device 12 for the rotating electrical machine. In the following, an example in which the rotating electrical machine 10 is housed in a transmission of an automobile or a transaxle in which a transmission and a final reduction gear are integrated will be described.

  The rotating electrical machine 10 includes a rotor 16 that rotates about a rotor shaft 14 and a stator 18 that is disposed so as to surround the rotor 16. The rotor 16 includes a substantially cylindrical rotor core 20 formed by laminating magnetic steel plates. The rotor shaft 14 is arranged coaxially with the cylindrical shaft of the rotor core 20. Permanent magnets 22 are arranged in the circumferential direction on the outer peripheral portion of the rotor core 20. The permanent magnet 22 is embedded in the outer peripheral portion of the rotor core 20. Alternatively, the permanent magnet 22 may be fixed to the outer peripheral surface of the rotor core 20.

  The stator 18 has an annular or cylindrical general shape, and includes a stator core 24 formed by laminating electromagnetic steel sheets. The stator core 24 has a substantially annular shape or a cylindrical shape, and has a plurality of teeth (not shown) protruding radially inward from the inner peripheral surface thereof. The teeth are arranged in the circumferential direction, and a space called a slot is formed in a portion between the teeth. A coil conductor is wound around the stator using this slot to form a coil 26. A portion of the coil 26 that is out of the slot, that is, a portion that is exposed from the end surface of the stator core 24 and is exposed to the outside is called a coil end. The coil end is indicated by reference numeral 28.

  The rotating electrical machine 10 is a liquid cooling type. A cooling liquid is placed in a case that houses the rotating electrical machine 10, and cooling is performed by this cooling liquid. As in this example, when stored in a transmission or the like of an automobile, the fluid used as the hydraulic fluid for the lubrication of each part of the transmission or the like and the hydraulic actuator of the transmission or the like may be used as the aforementioned cooling liquid. it can. The coolant is sent to a predetermined part in the transmission by the hydraulic pump 30. As the hydraulic pump 30, a hydraulic pump provided in the transmission can be used. Cooling liquid discharged from the hydraulic pump 30 is sent to a portion that needs to be cooled by the cooling liquid piping 32 to be cooled. In this embodiment, the coolant is sent to the coil 26, particularly the coil end 28, from the hole 34 formed in the side surface of the coolant pipe 32.

  The control device 12 includes a control unit 36, and the control unit 36 controls the electric power supplied to the rotating electrical machine 10 according to the input request and the operating situation, and drives the rotating electrical machine 10. For example, the driver's request such as the accelerator pedal operation amount 38 and the brake pedal operation amount 40 of the driver of the vehicle, and the storage amount 42 of the battery 50 that is mounted on the vehicle and serves as a source of driving power for the rotating electrical machine 10, The required drive output or regenerative output of the rotating electrical machine 10 is calculated from the driving situation such as the speed 44 of the automobile, and control corresponding to this is performed. The control unit 36 receives a signal representing a driver's request (accelerator operation amount, brake operation amount, etc.) and a signal representing a vehicle driving situation (battery storage amount, vehicle speed, etc.) at the command value calculation unit 46, A command value for driving the rotating electrical machine 10 is calculated. In the drive part 48, a drive signal is produced | generated based on the calculated command value. The drive signal is, for example, a PWM control signal. Based on this signal, DC power from the battery 50 is pulse-width modulated, converted into three-phase AC power, and supplied to the rotating electrical machine 10 as drive power. The command value calculation unit 46 and the drive unit 48 represent functions when the control unit 36 performs a predetermined calculation, and do not have to have an independent physical configuration.

  The control device 12 further includes a coil temperature detector 52 that detects the temperature of the coil 26, a coolant flow rate detector 54 that detects the flow rate of the coolant flowing through the coolant pipe 32, and output values of these detectors 52 and 54. And an output upper limit setting unit 56 for calculating and setting the output upper limit value of the rotating electrical machine. Similarly to the command value calculation unit 46 and the drive unit 48, the output upper limit setting unit 56 represents a function when the control unit 36 performs a predetermined calculation, and does not have an independent physical configuration. Good. The output upper limit setting unit 56 will be described in detail later.

  In order to prevent the demagnetization of the permanent magnet 22, it is important to monitor the temperature of the permanent magnet. However, the permanent magnet 22 is provided on the rotating rotor 16, and a special configuration is required to obtain a signal by attaching a detector thereto. For example, it is necessary to use a sliding contact such as transmission / reception of a signal using a radio and a slip ring, which is disadvantageous in terms of cost and space. In the rotating electrical machine 10 and the control device 12, the temperature of the permanent magnet 22 is substituted with the temperature of the coil 26 having a certain degree of correlation with the temperature of the permanent magnet 22. The coil temperature detector 52 detects this temperature. The coil temperature detector 52 is installed in contact with the conducting wire forming the coil 26. Although it can be installed for the conductor in the slot, it may be installed for the conductor of the coil end 28 when space is insufficient in the slot. In the rotating electrical machine 10, the rotating electrical machine 10 is installed with respect to the conducting wire of the coil end 28.

  As described above, the coolant supplied by the coolant pipe 32 is applied to the coil 26, and the coil 26 is thereby cooled. For this reason, when the flow rate of the coolant is large and a large amount of coolant is applied to the coil 26, the coil is cooled well and the temperature is lowered. Conversely, when the flow rate of the coolant is small, the detected coil temperature becomes high. On the other hand, since the cooling liquid is not directly supplied to the permanent magnet 22, the cooling effect by the cooling liquid is smaller than that of the coil 26. Therefore, the relationship between the temperature of the permanent magnet 22 and the coil 26 varies depending on the flow rate of the coolant.

  FIG. 2 is a schematic diagram showing how the relationship between the temperature of the permanent magnet 22 and the temperature of the coil 26 changes depending on the flow rate of the coolant. The temperature of the permanent magnet and the temperature of the coil have a positive correlation, but the relationship changes as the flow rate of the coolant changes as described above. That is, when the flow rate of the coolant is large, the coil 26 is further cooled, so that the coil temperature is lower than the temperature of the permanent magnet. The correlation at this time is shown by a line A1 in FIG. When the flow rate decreases, the coil temperature increases with respect to the magnet temperature, and changes to line A2 and line A3.

  In the case of a permanent magnet having a characteristic that demagnetization occurs at a high temperature, such as a neodymium magnet, it is necessary to operate so that the permanent magnet temperature does not exceed the upper limit value Tc. The coil temperature when the permanent magnet temperature reaches the upper limit value Tc differs depending on the flow rate of the coolant. When the upper limit value is determined only by the coil temperature, it is necessary to limit the output of the rotating electrical machine 10 based on the relationship between the coil temperature and the permanent magnet temperature (line A1) when the coolant flow rate is the highest. That is, it is necessary to control the rotating electrical machine 10 so that the coil temperature does not exceed the temperature T1 at which the permanent magnet temperature on the line A1 becomes the upper limit value Tc.

  FIG. 3 is a schematic diagram showing the relationship between the substitute temperature of the permanent magnet (coil temperature in the rotating electrical machine 10) and the upper limit value of the output of the rotating electrical machine. The output of the rotating electrical machine is limited by the line B1 so as not to exceed the temperature T1 shown in FIG. Control is performed to gradually lower the upper limit from a lower temperature at which the coil temperature reaches T1. The output limitation is executed by, for example, torque limitation or rotation speed limitation.

  When the relationship between the coil temperature, the permanent magnet temperature, and the coolant flow rate is as shown in FIG. 2, when the coolant flow rate is small, the temperature of the permanent magnet is not so high even if the coil temperature is high. That is, when the flow rate of the coolant is small, the temperature of the permanent magnet does not exceed the upper limit value Tc even at a temperature higher than the above-described coil temperature T1, for example, the temperatures T2 and T3 in FIG. Therefore, as shown in FIG. 3, when the flow rate is small, the output limit can be relaxed and the upper limit values can be set to lines B2 and B3. Thereby, the output of the rotary electric machine 10 can be used effectively in a wider range.

  In order to detect the coolant flow rate, a coolant flow rate detector 54 is disposed in the coolant pipe 32. The position where the coolant flow rate detector 54 is disposed is a position where the amount of coolant supplied for cooling the coil 26 can be detected. Preferably, a position where there is no branching or merging downstream from this position and the coil is cooled by the total amount of the coolant that has passed through this position is desirable. However, even if there is a branch on the downstream side, if there is no significant change in the ratio distributed to each branch after branching, it can be arranged at such a position.

  The output upper limit setting unit 56 holds in advance the output upper limit value of the rotating electrical machine that is determined corresponding to the set of the coil temperature and the coolant flow rate. When the detected coil temperature and coolant flow rate are acquired, the output upper limit values associated with these values are read out and sent to the command value calculation unit 46. The command value calculation unit 46 calculates the output to be output from the rotating electrical machine 10 based on the driver's request and the driving state of the automobile. If this output exceeds the output upper limit value, the output of the rotating electrical machine 10 is output to this output. Change to the upper limit. Alternatively, the command value calculation unit 46 may calculate an output that does not exceed the output upper limit value based on the driver's request, the driving situation, and the calculated output upper limit value. The command value calculation unit 46 sends an output command that does not exceed the upper limit set by the output upper limit setting unit 56 to the drive unit 48. In accordance with this output command, the drive unit 48 drives the rotating electrical machine 10.

  FIG. 4 is a diagram showing a configuration in which two rotating electrical machines are provided in one transmission or transaxle. About each component of a rotary electric machine, A or B is attached | subjected and shown to the same code | symbol as embodiment shown in FIG. 1, and detailed description is abbreviate | omitted. In FIG. 4, “A” is attached to each component of the left rotating electrical machine, and “B” is attached to each element of the right rotating electrical machine. The coolant pipe 32 branches to a pipe 32A and a pipe 32B and sends the coolant to each of the rotating electrical machines 10A and 10B. Coolant flow rate detectors 54A and 54B are disposed downstream of the branch points of the pipes 32A and 32B. In addition, downstream from the position where these detectors 54A and 54B are arranged, there is no branching or merging, and the cooling liquid passing through each position cools the rotating electrical machines 10A and 10B without excess or deficiency. Further, although not shown, the control device is also provided corresponding to each of the rotating electrical machines 10A and 10B. For each of the two rotating electrical machines 10A and 10B, an output upper limit value is set based on the coolant flow rate and the coil temperature. Further, an output upper limit value based on the coolant flow rate and the coil temperature may be set for any one of the rotating electrical machines.

  In the above description, the temperature of the coil, particularly the coil end, is used instead of the temperature of the permanent magnet. However, the temperature of the other part of the rotating electric machine may be substituted. Further, when the coolant is sent into the rotor and the permanent magnet is directly cooled, it is conceivable that the relationship between the permanent magnet temperature and the coil temperature is reversed. In other words, the temperature of the permanent magnet may be lower when the flow rate of the coolant is larger for the same coil temperature. Therefore, in correspondence with the configuration of the cooling system for the rotating electrical machine to be applied and the configuration such as the portion for obtaining the substitute temperature of the permanent magnet temperature, the relationship between the substitute temperature, the coolant flow rate, and the output upper limit value is obtained in advance. The output upper limit value is set according to this relationship.

  Furthermore, although the above output upper limit value is set based on the coil temperature (substitute temperature) and the coolant flow rate, the output upper limit value is once set based on the coil temperature, and the coolant flow rate is set to this upper limit value. Correction may be performed based on the output upper limit value.

  DESCRIPTION OF SYMBOLS 10 Permanent magnet rotary electric machine, 12 Control apparatus, 16 Rotor, 18 Stator, 22 Permanent magnet, 26 Coil, 28 Coil end, 30 Hydraulic pump, 32 Coolant piping, 36 Control part, 46 Command value calculation part, 48 Drive part , 52 Coil temperature detector, 54 Coolant temperature detector, 56 Output upper limit setting unit.

Claims (3)

A control device for a permanent magnet rotating electrical machine,
A temperature detector for detecting the temperature of the other part of the rotating electric machine instead of the temperature of the permanent magnet;
A flow rate detector that detects the flow rate of the coolant that is sent to a predetermined part of the rotating electrical machine and performs cooling;
An output upper limit setting unit that sets an output upper limit value of the rotating electrical machine based on the detected temperature and the detected flow rate;
A control device for a permanent magnet rotating electrical machine.   The control apparatus for a permanent magnet rotating electrical machine according to claim 1, wherein the output upper limit setting unit sets the output upper limit value to be higher when the detected flow rate is small. A control device for a permanent magnet rotating electrical machine,
A temperature detector for detecting the temperature of the other part of the rotating electric machine instead of the temperature of the permanent magnet;
A flow rate detector that detects the flow rate of the coolant that is sent to a predetermined part of the rotating electrical machine and performs cooling;
An output upper limit setting unit that sets an output upper limit value of the motor based on the detected temperature;
An output upper limit changing unit that changes the set output upper limit based on the detected flow rate;
A control device for a permanent magnet rotating electric machine having

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