Control device and control program of rotary electric machine system

Abstract

To enable a rotary electric machine system to generate heat efficiently.SOLUTION: A rotary electric machine system is provided with a rotary electric machine 10 having a multi-phase coil 11, and an inverter 20 that adjusts phase currents in each phase by ON / OFF of a plurality of switches 21 and 22 constituted of semiconductor switching elements. A control device 40 controls the ON / OFF of the switches 21 and 22 in the inverter 20. The control device 40 comprises: a determining part that determines whether there is a request for generating heat or not in the rotary electric machine system; and a switch control part that when it is determined that there is the request for generating heat, controls the switches 21 and 22 so that a transition time of at least either of a turn-on time and a turn-off time of the switches 21 and 22 becomes longer than a transition time when there is no request for generating heat.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a control device and a control program for a rotating electrical machine system. [Background technology]

[0002] Conventionally, as described in Patent Document 1, there is known a control device for an inverter that electrically connects a winding constituting a rotating electric machine to a battery. In this control device, when the battery is at a low temperature and the rotating electric machine is stopped, a discharge control is performed by applying a d-axis voltage by switching control of the inverter to cause a d-axis current to flow to the rotating electric machine, and a charge control is performed by lowering the d-axis voltage following the discharge control to return electrical energy from the coil of the rotating electric machine to the battery, alternately and repeatedly. This generates Joule heat in the battery, raising the temperature of the battery. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5849917 Summary of the Invention [Problem to be solved by the invention]

[0004] In vehicles, in addition to the heat demand for raising the temperature of the battery, various heat demands such as heating the vehicle interior are considered to exist. In this case, it is possible to respond to various heat demands by effectively generating heat with each switch of the inverter. In this regard, there is thought to be room for improvement in the technology for generating heat (generating heat) in the inverter according to the heat demand.

[0005] The present invention has been made in consideration of the above-mentioned problems, and has as its main object to efficiently generate heat in a rotating electrical machine system. [Means for solving the problem]

[0006] The means for solving the above problem is 1. A control device that is applied to a rotating electric machine system including a rotating electric machine having a multi-phase winding and an inverter that adjusts a phase current of each phase in the winding by turning on and off a plurality of switches made of semiconductor switching elements, and controls the on and off of the switches in the inverter, comprising: a determination unit that determines whether or not there is a heat generation request in the rotating electrical machine system; a switch control unit that controls the switch when it is determined that there is a heat generation request so that a transition time of at least one of turning on and turning off the switch is longer than a transition time when there is no heat generation request; Equipped with.

[0007] When there is a heat generation request from the rotating electric machine system, at least one of the transition times when the switch (semiconductor switching element) is turned on and off is set to be longer than when there is no heat generation request. This allows each switch of the inverter to generate heat due to an increase in the amount of switching loss. As a result, heat can be generated efficiently in the rotating electric machine system. "Heat generation" means generating heat, and "heat generation request" means requesting the generation of heat. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is an overall configuration diagram of a rotating electric machine system. [Diagram 2] FIG. 4 is a diagram showing the configuration of a switch drive circuit. [Diagram 3] 4 is a time chart showing changes in switch voltage Vsw and switch current Isw. [Figure 4] 4 is a time chart showing the rise in element temperature when the switch is turned on. [Diagram 5] A diagram showing the dq-UVW conversion process. [Figure 6] 4 is a time chart showing current waveforms of dq axis currents and phase currents of each phase. [Figure 7] FIG. 13 is a diagram showing a switching pattern when heat generation control is performed by energizing the d-axis. [Figure 8] FIG. 13 is a diagram showing a switching pattern when heat generation control is performed by energizing the d-axis. [Figure 9] 4 is a time chart showing changes in gate voltages of upper and lower arm switches. [Figure 10] 4 is a time chart showing an example of control of gate resistance switching in each phase. [Figure 11] FIG. 4 is a diagram showing the relationship between the electrical angle and the current ratio of each phase. [Figure 12] 1 is a time chart showing switching control for three states with different modulation rates. [Figure 13] A diagram showing the dq-UVW conversion process. [Figure 14] 4 is a timing chart for specifically explaining heat generation control by energizing the d-axis. [Figure 15] 5 is a flowchart showing a procedure for heat generation control while the vehicle is stopped. [Figure 16] 4 is a flowchart showing a procedure for heat generation control while the vehicle is traveling. [Figure 17] FIG. 13 is a graph showing the relationship between element temperature and the length of a loss increase period. [Figure 18] FIG. 4 is a diagram showing the meshing of gears in a gear device. [Figure 19] 4 is a time chart showing the changes in various parameters when a q-axis torque is generated. [Figure 20] 5 is a flowchart showing a procedure for heat generation control while the vehicle is stopped. [Figure 21] 4 is a time chart showing changes in gate voltages of upper and lower arm switches. [Figure 22] FIG. 13 is a diagram showing a configuration for changing the dead time in response to a heat generation request. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] (First embodiment) DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A rotating electric machine system according to an embodiment will now be described with reference to the drawings. The rotating electric machine system according to the present embodiment is mounted on an electric vehicle such as a battery electric vehicle (BEV) or a hybrid electric vehicle (HEV).

[0010] As shown in FIG. 1, the rotating electric machine system includes a rotating electric machine 10, an inverter 20 as a power converter, a battery 30 as a high-voltage power supply, and a control device 40. The rotating electric machine 10 is a brushless synchronous machine, and in this embodiment, is a permanent magnet synchronous machine. The rotating electric machine 10 includes a rotor (not shown) and three-phase (U-phase, V-phase, W-phase) coils 11 as a stator winding. The coils 11 are configured by star-connecting a U-phase coil, a V-phase coil, and a W-phase coil. The rotating electric machine 10 includes a rotation angle sensor 12 that detects a rotation angle (electrical angle) of the rotor, and a phase current sensor 13 that detects a phase current of each phase flowing through the coil 11. It is preferable that the phase current sensor 13 is provided for each of the three phases. However, the phase current sensor 13 may be provided for only two of the three phases.

[0011] The rotating electric machine 10 is provided as a power source for driving the vehicle, and the wheels are rotated by the rotation of the rotor. In this embodiment, the rotation of the rotor of the rotating electric machine 10 is transmitted to an input shaft of a gear device 51, and the rotation of the output shaft of the gear device 51 is transmitted to wheels 53 via an axle 52.

[0012] The inverter 20 includes a series connection of an upper arm switch 21 and a lower arm switch 22 for each phase. Each of the upper arm and lower arm switches 21, 22 is a semiconductor switching element, for example, an N-channel MOSFET. In each of the switches 21, 22, the high potential terminal is the drain, and the low potential terminal is the source. A diode 23 is connected in inverse parallel to each of the switches 21, 22 (semiconductor switching elements) as a freewheel diode. In each phase, the midpoint between the upper arm switch 21 and the lower arm switch 22 is connected to an end point of the coil 11 of the rotating electric machine 10. The semiconductor switching element may be an IGBT or the like.

[0013] A drive circuit 24 is connected to the gates of each of the switches 21, 22, and the drive circuit 24 turns the switches 21, 22 on and off based on a drive command from the control device 40. The drive circuit 24 is provided with a short circuit detection unit 25 that detects the occurrence of a short circuit in each of the switches 21, 22 of the upper and lower arms. The short circuit detection unit 25 detects the flow of an overcurrent due to a short circuit in the upper and lower arms, and forcibly turns off the switches 21, 22 upon detection of the overcurrent. Each of the switches 21, 22 is provided with an element temperature sensor 26 that detects the temperature of the semiconductor switching element.

[0014] The battery 30 is a secondary battery such as a lithium ion battery or a nickel metal hydride battery. The battery 30 is, for example, a battery pack including a series connection of a plurality of battery cells. The drains of the upper arm switches 21 of each phase are connected to the positive terminal of the battery 30 via a high potential side path 31. The sources of the lower arm switches 22 of each phase are connected to the negative terminal of the battery 30 via a low potential side path 32.

[0015] In addition, in the rotating electrical machine system, the inverter 20 and the battery 30 are provided with heat transfer units 61, 62, respectively, and the heat transfer units 61, 62 are connected to each other by a refrigerant passage 63 made of piping or the like. In the heat transfer unit 61 on the inverter 20 side, heat transfer is performed between the switches 21, 22 of the inverter 20 and the refrigerant flowing through the refrigerant passage 63. In addition, in the heat transfer unit 62 on the battery 30 side, heat transfer is performed between the battery 30 and the refrigerant flowing through the refrigerant passage 63. In this case, if a temperature difference occurs between the inverter 20 and the battery 30, heat is transferred (heat exchanged) between the inverter 20 and the battery 30 via the refrigerant flowing through the refrigerant passage 63. Although not shown in the figure, the refrigerant passage 63 is provided as a circulation path for circulating the refrigerant, and the refrigerant passage 63 is provided with a pump for circulating the refrigerant and a heat dissipation unit such as a radiator.

[0016] The control device 40 is mainly composed of a microcomputer, and the microcomputer has a CPU. The functions provided by the microcomputer can be provided by software recorded in a physical memory device and a computer that executes the software, by software alone, by hardware alone, or by a combination of these. For example, when the microcomputer is provided by an electronic circuit that is hardware, it can be provided by a digital circuit including a large number of logic circuits, or an analog circuit. For example, the microcomputer executes a program stored in a non-transitory tangible storage medium as a storage unit provided in the microcomputer. The program includes programs for various arithmetic processing. By executing the program, a method corresponding to the program is executed. The storage unit is, for example, a non-volatile memory. The program stored in the storage unit can be updated via a network such as the Internet, such as OTA (Over The Air).

[0017] The control device 40 receives detection signals from various sensors, such as the rotation angle sensor 12, the phase current sensor 13, and the element temperature sensor 26. The control device 40 performs switching control of the switches 21 and 22 constituting the inverter 20 based on the input detection values ​​in order to control the control amount (e.g., torque) of the rotating electric machine 10 to a command value. In this case, a PWM pulse is generated using a well-known PWM control method, and the switches 21 and 22 are switched. This causes the rotor of the rotating electric machine 10 to rotate, allowing the vehicle to run.

[0018] For example, when the vehicle is running, the control device 40 sets command values ​​for the d-axis current and the q-axis current based on the command torque of the rotating electric machine 10 and acquires the electrical angle θ (rotation angle) detected by the rotation angle sensor 12. Also, based on the current command values ​​and the electrical angle θ, it calculates a phase current command value for each phase. Then, it performs switching control of the switches 21, 22 in the inverter 20 by current feedback control using the detected currents detected by the phase current sensor 13 and the phase current command values.

[0019] In the battery 30 consisting of a secondary battery such as a lithium ion battery, deterioration is likely to occur when the battery temperature is low, and it is desirable to use the battery at a temperature suitable for each battery. Therefore, it is preferable to perform a process to increase the battery temperature when the battery 30 is in a low temperature state. In addition to the heat demand for raising the temperature of the battery, a vehicle is considered to have a heat demand such as heating the vehicle interior. In consideration of this point, in this embodiment, when a heat generation request occurs to promote heat generation in the rotating electric machine system, that is, when a request to generate heat occurs in the rotating electric machine system, the heat generation control is performed. For example, when the battery temperature is low, a heat generation request is transmitted from a higher-level control device or other external device to the control device 40, and the heat generation control is performed by the control device 40.

[0020] In this embodiment, the heat creation control is roughly divided into two types of control. One is heat creation control by increasing switching loss of each switch 21, 22 of the inverter 20, and the other is heat creation control by d-axis current supply that causes a d-axis current that does not generate torque in the rotating electric machine 10 when the vehicle is stopped (when the rotating electric machine 10 stops rotating). Each of these heat creation controls will be described in detail below. First, the heat creation control by increasing switching loss will be described.

[0021] 2 shows the configuration of the drive circuit 24 for the switch 21 in the inverter 20. Note that although the upper arm switch 21 will be described here, the drive circuit 24 for the lower arm switch 22 has the same configuration.

[0022] The drive circuit 24 has a drive IC 27 to which a drive command is input from the control device 40, and the switch 21 is turned on and off by the drive IC 27. The drive IC 27 controls the charging and discharging of the gate of the switch 21, and when the switch is on, the switch 21 is turned on by charging the gate due to application of a voltage, and when the switch is off, the switch 21 is turned off by discharging the gate.

[0023] The drive circuit 24 has a configuration that makes it possible to change the turn-on time, which is the transition time required for the switch 21 to transition from an off state to an on state, and the turn-off time, which is the transition time required for the switch 21 to transition from an on state to an off state, variable, thereby making it possible to adjust the switching loss in each switch 21. Specifically, by switching a gate resistor provided between the drive IC 27 and the gate of the switch 21, the time required for gate charging and discharging of the semiconductor switching element is adjusted, and the turn-on time and the turn-off time are variable. In this embodiment, a first gate resistor 28 and a second gate resistor 29 having different resistance values ​​are connected in parallel between the drive IC 27 and the gate of the switch 21, and the charging and discharging time (turn-on time, turn-off time) of the switch 21 is adjusted by switching between these gate resistors 28 and 29. The second gate resistor 29 has a resistance value larger than that of the first gate resistor 28. The first gate resistor 28 corresponds to a gate resistor for normal operation, and the second gate resistor 29 corresponds to a gate resistor for increased loss.

[0024] FIG. 3 is a time chart showing changes in the switch voltage Vsw between the drain and source of the switch 21 and the switch current Isw flowing between the drain and source.

[0025] Figure 3(a) shows the changes in Vsw and Isw during normal operation, i.e., when no control is performed to prevent an increase in switching loss. In this case, the hatched areas indicate the switching losses at turn-on and turn-off.

[0026] 3(b) shows the change in Vsw and Isw when the turn-on time and turn-off time are made longer than normal when controlling the increase in switching loss. In this case, the switching loss increases at the time of turn-on and turn-off, and the amount of heat generated in the switch 21 can be increased.

[0027] However, if the switching loss is increased at turn-on, the element temperature of the switch 21 increases sharply after turn-on begins. Therefore, if a short circuit occurs between the upper and lower arms, the switch 21 may become overheated due to excessive heat before the short circuit is detected, which may cause a risk of fire. That is, as shown in FIG. 4, when the switching loss increases as shown by the solid line, the slope of the element temperature rise is steeper than during normal operation as shown by the dashed and dotted line. In this case, there is a risk that the element temperature may exceed the ignition point before the time required for short circuit detection has elapsed.

[0028] In this embodiment, the turn-off time is made longer than the turn-on time in order to reduce heat generation on the turn-on side and increase heat generation on the turn-off side, as shown in Fig. 3(c). As a result, a larger switching loss occurs when the switch 21 is turned off than when it is turned on.

[0029] In Fig. 3(c), the turn-on time of the switch 21 is the same as when the switching loss is not increased (when there is no heat generation request), and the turn-off time is longer than when the switching loss is not increased (when there is no heat generation request). In other words, when the switching loss increases due to a heat generation request, the gate is charged via the first gate resistor 28 for normal operation when the switch is turned on, and the gate is discharged via the second gate resistor 29 for increased loss when the switch is turned off. This enables the current to be quickly cut off when a short circuit abnormality is detected in the upper and lower arms when the switch is turned on.

[0030] Next, the heat generation control by the d-axis current supply will be explained.

[0031] In the rotating electric machine 10, the d-axis and q-axis are virtual axes, and the d-axis current Id flowing on the d-axis, the q-axis current Iq flowing on the q-axis, and the phase currents Iu, Iv, and Iw flowing in the respective UVW phases are expressed by the following (Equation 1). In (Equation 1), θ is the electrical angle (rotation angle) of the rotating electric machine 10.

[0032]

number

[0033] In this embodiment, when the vehicle is stopped and traveling is stopped, current is passed through each phase of the coil 11 in a state in which the rotating electric machine 10 does not generate torque, i.e., in a state in which the rotating electric machine 10 stops rotating, to promote heat generation in the rotating electric machine system. This increases the temperature of the battery 30. Specifically, by performing switching control of the inverter 20 so that only the d-axis current of the d-axis current Id and the q-axis current Iq flows, the phase current of each phase is passed in a state in which no torque is generated in the rotating electric machine 10. In this case, the control device 40 calculates the phase currents Iu, Iv, and Iw of each phase in the above (Equation 1) by setting the stop electrical angle of the rotating electric machine 10 to the electrical angle θ and setting the q-axis current of the d-axis current Id and the q-axis current Iq to 0.

[0034] FIG. 5 shows the process of dq-UVW conversion when heat generation control is performed. FIG. 5 shows a three-phase conversion unit 71 that converts the dq-axis current command values ​​Id* and Iq* into phase current command values ​​Iu*, Iv*, and Iw* of each UVW phase. To the three-phase conversion unit 71, Asinφ is input as the d-axis current command value Id*, and 0 is input as the q-axis current command value Iq*. In addition, the electrical angle θ of the rotating electric machine 10 in a rotation-stopped state is input as the electrical angle θ. In "Asinφ", A is an amplitude command value that specifies the amplitude of the d-axis current, and φ is a phase that changes at a predetermined angular velocity. As a result, the d-axis current command value Id* is set as an AC current that changes at a frequency of, for example, about 20 Hz. In this case, an AC d-axis current that changes in both positive and negative directions is set as the d-axis current command value Id*, and phase current command values ​​Iu*, Iv*, Iw* that change in both positive and negative directions are calculated based on the d-axis current command value Id* (AC d-axis current).

[0035] FIG. 6 is a time chart showing the current waveforms of the dq-axis current and the phase current of each phase. In FIG. 6, the d-axis current Id changes in an AC waveform with a sinusoidal waveform on both the positive and negative sides while the q-axis current Iq is held at 0. The phase currents Iu, Iv, and Iw of each phase change in an AC waveform with an amplitude corresponding to the electrical angle θ (stop position) of the rotating electric machine 10. When the phase currents Iu, Iv, and Iw change in an AC waveform on both the positive and negative sides, a state in which a positive phase current flows in one of the three phases and a negative phase current flows in the remaining two phases is alternately switched to a state in which a positive phase current flows in two of the three phases and a negative phase current flows in the remaining one phase. Here, in the U-phase coil, V-phase coil, and W-phase coil of the coil 11, a current flowing from the anti-neutral point side to the neutral point side is defined as a positive current, and a current flowing in the opposite direction is defined as a negative current.

[0036] An example of a switching pattern when heat generation control by d-axis current is performed will be described with reference to Fig. 7 and Fig. 8. Fig. 7 shows a switching pattern when a positive current flows as the U-phase current and a negative current flows as the V-phase current and the W-phase current, and Fig. 8 shows a switching pattern when a positive current flows as the V-phase current and the W-phase current and a negative current flows as the U-phase current. Note that here, the three-phase switches 21 in the upper arm are referred to as switches 21U, 21V, and 21W, and the three-phase switches 22 in the lower arm are referred to as switches 22U, 22V, and 22W.

[0037] In FIG. 7(a), in the upper arm, the switch 21U is turned on and the switches 21V and 21W are turned off, and in the lower arm, the switch 22U is turned off and the switches 22V and 22W are turned on. As a result, a positive current flows as a U-phase current from the battery 30, and a negative current flows as a V-phase current and a W-phase current. In FIG. 7(b), following the state of FIG. 7(a), the switch 21U is turned off in the upper arm, so that the switches 21 of all phases are turned off, and the switches 22 of all phases are turned on in the lower arm. As a result, a current circulates through a return path including the lower arm switch 22 and the coil 11 of each phase. In FIG. 7(a) and (b), the switches 21U and 22U of the upper and lower arms of the U phase are alternately turned on and off, and the switching is repeated at a predetermined cycle during a period in which a positive current flows in the U phase.

[0038] In FIG. 8(a), the switches 21V and 21W are turned on and the switch 21U is turned off in the upper arm, and the switches 22V and 21W are turned off and the switch 22U is turned on in the lower arm. As a result, a positive current flows as the V- and W-phase current from the battery 30, and a negative current flows as the U-phase current. In FIG. 8(b), following the state in FIG. 8(a), the switches 21V and 21W are turned off in the upper arm, so that the switches 21 of all phases are turned off, and the switches 22 of all phases are turned on in the lower arm. As a result, a current circulates through a return path including the lower arm switches 22 and the coil 11 of each phase. In FIG. 8(a) and (b), the switches 21V and 21W of the upper arm and the switches 22V and 22W of the lower arm of the V- and W-phase are alternately turned on and off, and the switching is repeated at a predetermined cycle during a period in which a positive current flows through the V- and W-phase.

[0039] In the above heat generation control, phase currents Iu, Iv, and Iw flow in all phases according to the phase current command values ​​Iu*, Iv*, and Iw* for each phase that are set based on the AC d-axis current. In this case, in the inverter 20, switching control is performed in all phases, and control of increasing switching loss is also performed during the switching control of all phases. By increasing switching loss in the switches 21 and 22 of all phases in the inverter 20, heat generation is dispersed in each switch, unlike a case in which switching loss is increased only in some phases, and thus heat generation in the rotating electrical machine system is performed efficiently.

[0040] As shown in FIG. 7(b) and FIG. 8(b), when a current is circulated through a path including the lower arm switch 22 of each phase and the coil 11, a current flows from the source to the drain in the lower arm switch 22 of one of the phases (the switch 22U in FIG. 7(b) and the switches 22V and 22W in FIG. 8(b)), but it is also possible to pass the current through the diode 23. In this case, if a current is passed through the lower arm switch 22 in an on state, the conduction loss is reduced, so that the loss is considered to be smaller than when the diode 23 is energized. Furthermore, when a current flows through the diode 23, an increase in switching loss due to the on / off of the lower arm switch 22 cannot be expected. From these facts, when a current flows from the source to the drain of the lower arm switch 22 during current circulation, it is considered that there are cases where the advantage of controlling the increase in switching loss by turning the lower arm switch 22 on and off is not obtained.

[0041] In consideration of this, when turning on the upper arm switch 21 in any phase to pass a phase current through the coil 11 and then turning off the upper arm switch 21 to return the phase current, it is preferable to keep the lower arm switch 22 in the same phase as the upper arm switch 21 in the off state and return the phase current through the diode 23 connected in parallel to the lower arm switch 22. In this case, it is preferable that, among the switches 21 and 22 of the upper and lower arms of the inverter 20, only the upper arm switch 21, which is expected to increase switching loss due to on / off, is switched, and the lower arm switch 22 is not switched. In Fig. 7(b), the switch 22U is not switched, so that the current is returned through the diode 23 of the U-phase lower arm, and in Fig. 8(b), the switches 22V and 22W are not switched, so that the current is returned through the diode 23 of the V- and W-phase lower arms.

[0042] FIG. 9 shows the transition of the gate voltages of the switches 21U and 22U of the upper and lower arms. In FIG. 9, (a) shows the transition of the gate voltages of the switches 21U and 22U in normal operation, and (b) shows the transition of the gate voltages of the switches 21U and 22U when switching loss increases. In FIG. 9(b), the turn-off time of the switches 21U and 22U is longer than that in FIG. 9(a), and there is a concern that the switches 21U and 22U will be turned on at the same time (X in the figure). In other words, in the switching of the upper and lower arms, a dead time is set in anticipation of the time required for turn-off in normal operation, but if the turn-off is delayed, the dead time will elapse before the turn-off is completed, and there is a concern that the upper and lower arms will be short-circuited.

[0043] 9(c), of the switches 21U and 22U of the upper and lower arms, only the switch 21U of the upper arm is switched on. This prevents the occurrence of a short circuit in the upper and lower arms even if the turn-off time of the switch 21U is longer than normal (even if the turn-off is delayed).

[0044] In addition, when the phase current of each phase is changed to both positive and negative AC, the amplitudes of the phase currents of each phase do not match as shown in Fig. 6, so the heat generation amount of each switch 21, 22 differs for each phase, and as a result, the element temperature of each phase may differ. Therefore, in this embodiment, in order to match the heat generation amount of each switch 21, 22 in each phase, the period during which the switching loss is increased (the period during which the gate resistance value is increased) is adjusted for each phase.

[0045] Fig. 10 shows an example of control of gate resistance switching in each phase. In Fig. 10, when the phase current of each phase changes to both positive and negative AC, the amplitude of the U-phase current is the largest, followed by the V-phase current and the W-phase current. Therefore, in heat generation control by d-axis current, it is expected that the U-phase switch will be the hottest and the W-phase switch will be the coldest among the switches 21 and 22 of each phase. Therefore, in this embodiment, the loss increase period during which switching loss is increased is set variably based on the magnitude of the phase current flowing in each phase.

[0046] Specifically, the control device 40 detects or estimates the amplitude of the phase current of each phase, and sets a period during which the gate resistance value is increased in each phase, i.e., a loss increase period, based on the difference in the current amplitude of each phase. The loss increase period is preferably set as a time ratio indicating the proportion of the loss increase period in one period when the phase current of each phase changes to AC. In Fig. 10, since the amplitude of the phase current of each phase is U phase>V phase>W phase, the period during which the gate resistance value is increased (loss increase period) is set to the shortest in the U phase, and the period during which the gate resistance value is increased (loss increase period) is set to the longest in the W phase.

[0047] The control device 40 may set a period during which switching loss is increased for each phase based on the element temperature detected by the element temperature sensor 26. In this case, the control device 40 sets a target value (target temperature) of the element temperature in the switch of each phase, and sets a period during which switching loss is increased, i.e., a period during which the gate resistance value is increased, based on the deviation between the element temperature detected by the element temperature sensor 26 and the target temperature. This makes it possible to control the switches 21 and 22 of each phase to a desired temperature. Note that, when only the switch 21 of the upper arm among the switches 21 and 22 of the upper and lower arms is switched, it is preferable to set a loss increase period for only that switch 21 by element temperature feedback control.

[0048] As described above, by setting the loss increase period by the element temperature feedback control, even if the amplitudes of the phase currents of the respective phases differ, it is possible to suppress the variation in the element temperature caused by the differences.

[0049] In addition, since the relationship between the dq-axis current and the phase current has electrical angle dependency, depending on the electrical angle θ of the rotating electric machine 10, there may be cases where almost no current flows in some phases, which may have an adverse effect on the loss increase amount of each phase. In other words, when the phase current command values ​​Iu*, Iv*, and Iw* of each phase are set by the above (Equation 1), depending on the electrical angle θ of the rotating electric machine 10 in the rotation stopped state, it is considered that the phase current of any phase becomes a current value of 0 or near 0, and the difference in the heat generation amount between the phases becomes excessively large. Therefore, in this embodiment, as the electrical angle θ of the rotating electric machine 10, an electrical angle θ at which all the phase currents of each phase are equal to or greater than a predetermined threshold value is set (angle setting unit), and the phase current command values ​​Iu*, Iv*, and Iw* of each phase are set based on the electrical angle θ.

[0050] Specifically, in the case where the current ratio of the phase currents of the respective phases changes according to the electrical angle θ as shown in FIG. 11, the electrical angle θ when the heat generation control by the d-axis current is performed may be within a predetermined range Ra where the current ratio of the respective phases is equal to or greater than the threshold value Th. The current ratio is the ratio of the phase current of each phase to the total current flowing through the coil 11. In FIG. 11, the phase current of any phase is 0 when the electrical angle θ is 30 degrees, 90 degrees, 150 degrees, 210 degrees, 270 degrees, and 330 degrees, and therefore the range excluding the vicinity of each of these angles is set as the predetermined range Ra. In this case, if the detected electrical angle θa detected by the rotation angle sensor 12 in the rotation stop state of the rotating electric machine 10 is not within the predetermined range Ra, the rotating electric machine 10 may be caused to generate torque, and the electrical angle θ may be manipulated so as to fall within the predetermined range Ra.

[0051] Furthermore, while the vehicle is traveling, the modulation factor in the inverter 20 changes with changes in the operating state of the rotating electric machine 10. Furthermore, the change in modulation factor changes the drive duty of each of the switches 21, 22. Here, when the modulation factor is large, if the on time of the drive pulse (PWM pulse) of each of the switches 21, 22 becomes shorter than a predetermined time, it becomes difficult to extend the turn-on time or turn-off time, that is, to control the increase in switching loss.

[0052] Therefore, in this embodiment, when the on-time of the drive pulse of the switches 21 and 22 is shorter than a predetermined time, heat creation control due to switching loss increase is not performed. Fig. 12 is a time chart showing switching control in three states with different modulation factors. In Fig. 12, in the case of (c), the on-time of the drive pulse is shorter than the predetermined time, so switching loss increase is not performed. In the case of Fig. 12(c), switching loss increase may not be performed throughout the entire period, or switching loss increase may not be performed only during the period when the on-time of the drive pulse is shorter than the predetermined time.

[0053] Incidentally, when performing heat generation control by d-axis current application while the vehicle is stopped (when the rotating electric machine 10 is stopped), if the electrical angle of the rotating electric machine 10 recognized by the control device 40 differs from the actual electrical angle, an unintended q-axis current may flow. In this case, it is considered that unnecessary torque is generated in the rotating electric machine 10 even when the vehicle is stopped, and the deviation of the electrical angle may increase cumulatively. Specifically, in the case where the detected angle of the rotation angle sensor 12 is input as the electrical angle θ in the three-phase conversion unit 71 shown in FIG. 5, if a detection error of the rotation angle sensor 12 occurs, the recognized angle of the control device 40 differs from the actual electrical angle. In particular, it is considered that an electrical angle error of about several degrees occurs when the vehicle is stopped. There is a concern that unnecessary rotation may occur in the rotating electric machine 10 due to this miscalculation of the electrical angle.

[0054] Therefore, in this embodiment, as a control before the heat creation control by d-axis current, a DC d-axis current is passed through the rotating electric machine 10 to perform alignment control so that the electrical angle θ of the rotating electric machine 10 becomes the recognized angle (command angle α) recognized by the control device 40, and after the alignment control, heat creation control by the AC d-axis current is performed. As a result, the actual electrical angle is matched with the electrical angle recognized by the control device 40, and under the premise that the actual electrical angle is the command angle α, heat creation control of all phases is performed by changing the d-axis current to AC without referring to the detection value of the rotation angle sensor 12.

[0055] Figure 13(a) is a diagram showing the processing of dq-UVW conversion when performing alignment control, and Figure 13(b) is a diagram showing the processing of dq-UVW conversion when performing heat creation control using AC d-axis current.

[0056] As shown in FIG. 13(a), A1 is input to the three-phase conversion unit 71A as the d-axis current command value Id*, and 0 is input as the q-axis current command value Iq*. A predetermined command angle α is input as the electrical angle θ. As described in FIG. 11, the command angle α is an angle (angle within a predetermined range Ra) at which the total current of each phase is equal to or greater than a predetermined threshold. The three-phase conversion unit 71A calculates the phase current command values ​​Iu*, Iv*, and Iw* of each phase based on the d-axis current command value Id* (=A1) and the command angle α. In this case, the d-axis current command value Id* is a DC d-axis current, and the phase current command values ​​Iu*, Iv*, and Iw* are calculated as DC phase currents. Then, when performing the position alignment control, the phase currents of each phase are controlled by the phase current command values ​​Iu*, Iv*, and Iw* calculated by the three-phase conversion unit 71A.

[0057] The calculation process of the phase current command values ​​Iu*, Iv*, Iw* in the three-phase conversion unit 71A corresponds to the "first setting process", and the alignment control using the phase current command values ​​Iu*, Iv*, Iw* corresponds to the "first current control".

[0058] 13(b), A2·sinφ is input to the three-phase conversion unit 71B as the d-axis current command value Id*, and 0 is input as the q-axis current command value Iq*. Similarly to the three-phase conversion unit 71A, a predetermined command angle α is input as the electrical angle θ. The three-phase conversion unit 71B calculates phase current command values ​​Iu*, Iv*, Iw* that change in both positive and negative directions using the AC d-axis current that changes in both positive and negative directions as the d-axis current command value Id*.

[0059] The calculation process of the phase current command values ​​Iu*, Iv*, Iw* in the three-phase conversion unit 71B corresponds to the "second setting process", and the heat creation control using the phase current command values ​​Iu*, Iv*, Iw* corresponds to the "second current control".

[0060] In the three-phase conversion unit 71A shown in FIG. 13(a), the maximum absolute value of the DC d-axis current is A1, and in the three-phase conversion unit 71B shown in FIG. 13(b), the maximum absolute value of the AC d-axis current is A2. A1 and A2 are amplitude command values ​​that define the amplitude of the d-axis current. A1 and A2 may have a relationship of A1>A2. In other words, the absolute value of the DC d-axis current may be greater than the absolute value of the AC d-axis current. In this case, A2 for defining the AC d-axis current may be determined based on the magnitude of the required amount of heat generation, and A1 may be determined as a value greater than A2. For example, A2 may be determined based on the element temperatures of the switches 21 and 22. However, A1 and A2 may be A1=A2.

[0061] Fig. 14 is a time chart for specifically explaining the alignment control shown in Fig. 13 and the heat generation control by the AC d-axis current. In Fig. 14, as the rotor angle of the rotating electric machine 10, the detected electrical angle θa (sensor value) detected by the rotation angle sensor 12 is indicated by a dashed line, the actual electrical angle θb (true value) in the rotating electric machine 10 is indicated by a dashed line, and the command angle α, which is a constant value, is indicated by a solid line. In this example, the detected electrical angle θa has an angle error with respect to the actual electrical angle θb.

[0062] 14, alignment control is performed in period T1 in response to a heat generation request. Specifically, the electrical angle θ of the rotating electric machine 10 is set as a command angle α, a DC d-axis current is set as a d-axis current command value Id*, and the phase current of each phase of the coil 11 is controlled by phase current command values ​​Iu*, Iv*, and Iw* calculated based on the command angle α and the DC d-axis current. As a result, the electrical angle of the rotating electric machine 10 is adjusted to the command angle α, which is an angle recognized by the control device 40. At this time, even if the detected electrical angle θa has a detection error, the electrical angle of the rotating electric machine 10 is manipulated to a desired electrical angle without being affected by the detection error.

[0063] Thereafter, in a period T2, heat generation control is performed using the AC d-axis current. Specifically, the electrical angle θ of the rotating electric machine 10 is set as a command angle α, and the AC d-axis current is set as the d-axis current command value Id*, and the phase current of each phase of the coil 11 is controlled by the phase current command values ​​Iu*, Iv*, and Iw* calculated based on the command angle α and the AC d-axis current. At this time, current is passed through each phase of the coil 11 while the electrical angle of the rotating electric machine 10 is held at the command angle α adjusted by the previous alignment control. In addition, since the deviation between the recognized angle of the control device 40 and the actual electrical angle is suppressed, the generation of unintended q-axis torque is suppressed, and the rotating electric machine 10 is held in a rotation stop state.

[0064] 15 is a flowchart showing the procedure of heat creation control while the vehicle is stopped. This process is repeatedly executed at a predetermined cycle by the control device 40 when the vehicle is stopped, for example, when the power switch (IG switch) of the vehicle is in the off state. When the vehicle is stopped, heat creation control is performed by increasing the switching loss of each of the switches 21 and 22, and by passing current through the d-axis, which does not generate torque in the rotating electric machine 10.

[0065] In FIG. 15, in step S11, it is determined whether a heat generation request has occurred. For example, if a heat generation request has been received from a higher-level control device, step S11 is answered in the affirmative. If a heat generation request has occurred, the process proceeds to the following step S12, and if no heat generation request has occurred, the process ends.

[0066] In step S12, the control mode of the inverter 20 is set to the switching loss increase mode, whereby control of increasing switching loss is appropriately performed in the switching control of the inverter 20 while the vehicle is stopped.

[0067] Then, in step S13, the detected electrical angle θa detected by the rotation angle sensor 12 is obtained. In the following step S14, it is determined whether the detected electrical angle θa is within a predetermined range Ra. The predetermined range Ra is a range that specifies the electrical angle at which all of the phase currents of the respective phases of the coil 11 are equal to or greater than a predetermined threshold value. In step S14, if the detected electrical angle θa is within the predetermined range Ra, the process proceeds to step S15, and if the detected electrical angle θa is not within the predetermined range Ra, the process proceeds to step S16.

[0068] In step S15, the detected electrical angle θa is set as a command angle α to be used for heat generation control by d-axis current application. In addition, in step S16, a predetermined electrical angle within a predetermined range Ra is set as the command angle α. At this time, in order to prevent the rotor angle of the rotating electric machine 10 from changing excessively, it is preferable to set the command angle α so that the change from the detected electrical angle θa is within a predetermined value. The processing of steps S15 and S16 ensures that a minimum current flows in each phase.

[0069] Thereafter, in steps S17 and S18, a DC d-axis current is set as the d-axis current command value Id*, and alignment control is performed to adjust the electrical angle of the rotating electrical machine 10 to the command angle α. That is, in step S17, the d-axis current command value Id* is set to A1, the q-axis current command value Iq* is set to 0, and the electrical angle θ is set to the command angle α, and the phase current command values ​​Iu*, Iv*, and Iw* are calculated by dq / UVW conversion. In the following step S18, switching control is performed for the switches 21 and 22 of each phase based on the phase current command values ​​Iu*, Iv*, and Iw* calculated in step S17, and the phase currents flowing through the coils 11 in each phase are controlled.

[0070] When a DC d-axis current is passed in the position alignment control, control to prevent an increase in switching loss in each of the switches 21 and 22 is not performed.

[0071] Thereafter, in steps S19 to S21, the AC d-axis current is set as the d-axis current command value Id*, and heat generation control is performed by the d-axis current supply. At this time, the control device 40 also performs heat generation control by increasing switching loss.

[0072] In detail, in step S19, the d-axis current command value Id* is set to A2·sinφ, the q-axis current command value Iq* is set to 0, and the electrical angle θ is set to the command angle α, and the phase current command values ​​Iu*, Iv*, and Iw* are calculated by dq / UVW conversion.

[0073] In the next step S20, a loss increase period during which switching loss is increased is set based on the magnitude of the phase current flowing through each phase. At this time, since the amplitude of the phase current of each phase is determined according to the command angle α of the rotating electric machine 10, it is advisable to set the loss increase period for each phase based on the current amplitude of each phase. As a result, a period during which the gate resistance value is increased (loss increase period) is set for each phase, for example, as shown in FIG. 10.

[0074] After that, in step S21, based on the phase current command values ​​Iu*, Iv*, Iw* calculated in step S19, switching control is performed on the switches 21, 22 of each phase to control the phase current flowing through each phase of the coil 11. At this time, the control device 40 performs the following processes to control the increase in switching loss. (1) In the drive circuit 24 of the inverter 20, the gate resistance of each of the switches 21, 22 is switched to a gate resistance for increased loss, and the transition time when the switches are turned on and off is lengthened. During the loss increase period set in step S20, the gate resistance of each of the switches 21, 22 is set to the second gate resistance 29 for increased loss, and during periods other than the loss increase period, the gate resistance of each of the switches 21, 22 is set to the first gate resistance 28 for normal operation. (2) When the switches 21 and 22 are turned on and off, the turn-off time is set to be longer than the turn-on time. At this time, it is preferable to set the turn-on time to the same time as when there is no heat generation request, and to set the turn-off time to be longer than when there is no heat generation request. (3) Of the upper and lower arm switches 21, 22 of the inverter 20, only the upper arm switch 21, which is likely to experience an increase in switching loss due to on / off switching, performs switching, and the lower arm switch 22 does not perform switching.

[0075] In addition, instead of the above (2), it is also possible to make both the turn-on time and the turn-off time longer than when there is no heat generation request. Also, instead of the above (3), it is also possible to have both the switches 21 and 22 of the upper and lower arms of the inverter 20 perform switching.

[0076] 16 is a flowchart showing the procedure of heat creation control while the vehicle is traveling. This process is repeatedly executed at a predetermined cycle by the control device 40 while the vehicle is traveling, for example, when the power switch (IG switch) of the vehicle is in the on state. While the vehicle is traveling, heat creation control is performed by increasing the switching loss of each of the switches 21 and 22.

[0077] 16, in step S31, it is determined whether or not a heat generation request has occurred. For example, if a heat generation request has not been received from a higher-level control device, the result of step S31 is negative and the process proceeds to step S32. In step S32, the control mode of the inverter 20 is set to the normal mode, and in the following step S33, the control of the normal mode is performed as the switching control of the inverter 20.

[0078] Also, if a heat generation request has occurred, the process proceeds to step S34. In step S34, it is determined whether the on-time of the PWM pulse that turns on and off each switch 21, 22 is longer than a predetermined time TH. If step S34 is positive, the process proceeds to step S35, and if step S34 is negative, the process proceeds to step S32. At this time, if step S34 is negative, that is, if the on-time of the PWM pulse is shorter than the predetermined time TH, the switching loss increase is not performed.

[0079] In step S35, the control mode of the inverter 20 is set to the switching loss increasing mode, whereby control of increasing switching loss is appropriately performed in the switching control of the inverter 20 while the vehicle is running.

[0080] In step S36, the element temperature (switch temperature) detected by the element temperature sensor 26 is acquired, and in the following step S37, a loss increase period during which control of switching loss increase is performed is set based on the element temperature. Specifically, the loss increase period may be set using the relationship shown in FIG. 17, for example. In FIG. 17, a relationship is defined such that the lower the element temperature, the longer the loss increase period. The loss increase period may be set as a time ratio indicating the proportion of the loss increase period in one cycle when the phase current of each phase changes to AC. The loss increase period may be set for each phase.

[0081] After that, in step S38, the following processes are carried out as heat generation control due to an increase in switching loss. In the drive circuit 24 of the inverter 20, the gate resistance of each of the switches 21, 22 is switched to a gate resistance for increased loss, thereby lengthening the transition time when the switches are turned on and off. During the loss increase period set in step S37, the gate resistance of each of the switches 21, 22 is set to the second gate resistance 29 for increased loss, and during periods other than the loss increase period, the gate resistance of each of the switches 21, 22 is set to the first gate resistance 28 for normal operation. When the switches 21 and 22 are turned on and off, the turn-off time is set to be longer than the turn-on time. At this time, it is preferable to set the turn-on time to be the same as when there is no heat generation request, and the turn-off time to be longer than when there is no heat generation request. Of the upper and lower arm switches 21, 22 of the inverter 20, only the upper arm switch 21, which is likely to experience an increase in switching loss due to on / off switching, is switched on and off, and the lower arm switch 22 is not switched on.

[0082] In addition, both the turn-on time and the turn-off time may be longer than when there is no heat generation request. Also, switching may be performed by both the switches 21, 22 of the upper and lower arms of the inverter 20.

[0083] According to the present embodiment described above in detail, the following excellent effects can be obtained.

[0084] When there is a heat generation request from the rotating electric machine system, at least one of the transition times when the switches 21, 22 (semiconductor switching elements) in the inverter 20 are turned on and off is set to be longer than when there is no heat generation request. This allows the switches 21, 22 of the inverter 20 to generate heat due to an increase in the amount of switching loss. As a result, heat can be generated efficiently in the rotating electric machine system.

[0085] Since the element temperature rises faster when heat is generated due to an increase in switching loss than during normal operation, if a short circuit occurs between the upper and lower arms of the inverter 20, there is a concern that the element temperature may rise excessively before short circuit detection is performed when the switch is turned on. In this regard, since a configuration is adopted in which a larger switching loss occurs when the switches 21 and 22 are turned off than when they are turned on, the turn-on time can be relatively short. This makes it possible to prevent the element temperature from rising excessively before short circuit detection when the switch is turned on.

[0086] In a situation where a short circuit occurs between the upper and lower arms in the inverter 20, it is necessary to quickly cut off the current when a short circuit is detected at switch-on. In consideration of this, when there is a heat generation request, the turn-on time of the switches 21 and 22 is set to the same time as when there is no heat generation request, and the turn-off time is set to be longer than when there is no heat generation request. In this case, since an increase in switching loss at turn-on is not expected, the switches 21 and 22 can quickly cut off the current when a short circuit is detected.

[0087] When heat generation control by d-axis current is performed, the upper arm switch 21 of any phase is turned on to pass the phase current of each phase, and then the upper arm switch 21 is turned off to return the phase current. The lower arm switch 22 of the same phase as the upper arm switch 21 is kept in the off state, and the phase current is returned via the diode 23 connected in parallel to the lower arm switch 22. In this case, even if the lower arm switch 22 does not control the increase in switching loss, heat generation due to the current flowing through the diode 23 can be expected. In addition, in a configuration in which the on / off transition time of the switches 21 and 22 is long, there is a concern of a short circuit between the upper and lower arms. However, since only the upper arm switch 21 of the upper and lower arm switches 21 and 22 is switched, the occurrence of a short circuit between the upper and lower arms is suppressed.

[0088] During vehicle running, the drive duty changes according to the vehicle running state, and the on-time of the PWM pulse may become shorter than the predetermined time. In addition, when the on-time of the PWM pulse is short, it is considered that the effect on the current control caused by extending the transition time of the switches 21 and 22 becomes large. In consideration of this point, the configuration is such that the switching loss is not increased when the on-time of the PWM pulse is shorter than the predetermined time. This makes it possible to suppress the adverse effect of heat generation control caused by the switching loss increase on the current control during vehicle running.

[0089] The period for lengthening the transition times (turn-on time, turn-off time) of the switches 21 and 22, i.e., the period for increasing the switching loss, is set based on the element temperature (switch temperature) of the semiconductor switching element. This makes it possible to properly manage the element temperature when implementing heat generation control due to increased switching loss, thereby suppressing deterioration of the semiconductor switching elements and preventing overheating.

[0090] In a configuration in which current control (heat generation control by AC d-axis current) is performed so that a phase current that changes between positive and negative flows through each phase of the coil 11 when the rotating electric machine 10 is in a rotation-stopped state (when the vehicle is stopped), the switches 21, 22 are turned on and off in all phases of the coil 11. When this current control is performed, heat generation control is performed by increasing switching loss (control in which the transition time of the switches 21, 22 of each phase is lengthened). In this case, it is possible to cause switching loss in the switches 21, 22 of all phases, and it is possible to eliminate a situation in which heat is generated only in the switches of some phases.

[0091] In the case of heat generation control by d-axis current, when the phase current of each phase is changed to both positive and negative, the amplitude of the phase current in each phase may not match, and the amount of heat generated by each switch 21, 22 may differ for each phase. In consideration of this, a period in which the transition time (turn-on time, turn-off time) of the switches 21, 22 is lengthened, that is, a period in which control for increasing switching loss is performed, is set based on the magnitude of the phase current of each phase. Specifically, the time ratio of the period in which the gate resistance is increased (the time ratio of the period in which the second gate resistor 29 for increasing loss is used) is adjusted for each phase. This makes it possible to reduce the difference in the amount of heat generated by the switches 21, 22 of each phase, even if the amplitude of the phase current in each phase does not match.

[0092] When current control is performed so that a phase current that changes between positive and negative AC current flows through each phase of the coil 11 while the rotating electric machine 10 is stopped, it is possible that the phase current of any one of the phases will have a current value of 0 or close to 0 (i.e., bias will occur in the current flowing through each phase) depending on the electrical angle θ of the rotating electric machine 10, causing an excessively large difference in the amount of heat generated between the phases. In this regard, since current control is performed so that all of the phase currents are equal to or greater than a predetermined threshold while the rotating electric machine 10 is stopped, it is possible to prevent current from flowing unevenly through any one of the phases, and to prevent an excessively large difference in the amount of heat generated between the phases.

[0093] When it is determined that there is a heat generation request in the rotating electric machine system and the rotating electric machine 10 is in a rotation stop state, in order to pass a phase current that changes in both positive and negative directions to each phase of the coil 11, an AC d-axis current is set as a d-axis current command value, and a phase current command value is set based on the AC d-axis current. According to this configuration, a phase current flows in all phases according to the phase current command value of each phase set based on the AC d-axis current, and switching control is performed by the switches 21 and 22 of all phases in the inverter 20. Therefore, heat generation is performed by switching operation of all phases, and the amount of heat generation in the inverter 20 can be increased compared to when heat generation is performed by switching operation of only some phases. In addition, when heat generation is performed by switching control of only some phases, it is considered that some switches 21 become high temperature and the heat generation control is limited, but such inconvenience can be suppressed. As a result, heat generation can be efficiently performed in the rotating electric machine system.

[0094] When there is a heat generation request and the rotating electric machine 10 is in a rotation stop state, a phase current command value for each phase is set based on a command angle α, which is the electrical angle θ of the rotating electric machine 10, and a DC d-axis current, which is a d-axis current command value, and the phase current is controlled by the phase current command value. Then, a phase current command value for each phase is set based on the command angle α and the AC d-axis current, and the phase current is controlled by the phase current command value. In this case, heat generation can be performed by flowing an AC d-axis current in a state where the electrical angle θ of the rotating electric machine 10 is fixed to the recognized angle (command angle α) of the control device 40. This makes it possible to suppress an inconvenience in which the rotating electric machine 10 rotates unintentionally due to a detection error of the rotation angle sensor 12 in heat generation control by d-axis current supply.

[0095] When performing the alignment control using the DC d-axis current, the absolute value of the DC d-axis current is set to be greater than the absolute value of the AC d-axis current. This allows the alignment control, which is performed prior to the heat generation control using the AC d-axis current, to be performed appropriately.

[0096] When performing alignment control using DC d-axis current, the command angle α is set to an electrical angle θ at which all of the phase currents in the coil 11 are equal to or greater than a predetermined threshold value. This makes it possible to prevent current from flowing unevenly in any of the phases in heat generation control using d-axis current that is performed following alignment control, and to prevent the difference in heat generation between the phases from becoming excessively large.

[0097] In alignment control using the DC d-axis current, switching is performed in some phases, so there is a concern that when controlling for increased switching loss, heat generation may vary between phases. In consideration of this, alignment control using the DC d-axis current does not control for increased switching loss, but heat generation control using the AC d-axis current does control for increased switching loss. This makes it possible to prevent excessive temperature differences from occurring in the switches of each phase when implementing alignment control.

[0098] Second embodiment The rotating electric machine system shown in FIG. 1 has a configuration in which the rotation of the rotor of the rotating electric machine 10 is transmitted to the axle 52 via a gear device 51. The rotation of the rotor of the rotating electric machine 10 is transmitted to the axle side by the meshing of the gears (cogwheels) of the gear device 51. In this case, as shown in FIG. 18, a gap called backlash exists in the meshing of the gears to realize smooth rotation, and within the range of the backlash, the resistance received by the rotor of the rotating electric machine 10 is small, so the gear rotates with a small torque, and a gear rattle noise occurs. Therefore, when heat generation control is performed by applying current to the d-axis while the rotating electric machine 10 is stopped from rotating, if a small torque is generated alternately on both the positive and negative sides, there is a concern that the gear device 51 may continuously generate a gear rattle noise.

[0099] Therefore, in this embodiment, when heat generation control is performed by d-axis current application, a torque is generated in one direction of the rotation of the rotating electric machine 10, and current control is performed so that the absolute value of the torque does not exceed a predetermined value. In this case, it is preferable to generate AC currents of each phase by the d-axis current, and control the torque by the q-axis current. Specifically, when performing dq / UVW conversion, the control device 40 sets the d-axis current command value Id* to Asinφ, and calculates the q-axis current command value Iq* by the following (Equation 2). Then, based on the d-axis current command value Id* and the q-axis current command value Iq*, it calculates the phase current command values ​​Iu*, Iv*, and Iw*.

[0100]

number

[0101] Fig. 19 is a time chart showing parameter changes when q-axis torque is generated in heat generation control by d-axis current application. In Fig. 19, the phase current of each phase flows as shown in the figure according to the setting of the d-axis current and the q-axis current. In this case, the torque of the rotating electric machine 10 is continuously generated without crossing 0. As a result, in the gear device 51, each gear is held in tooth contact on one side in the rotation direction, and the generation of teeth rattle noise is suppressed.

[0102] In addition, when performing the alignment control, it is preferable to set the command angle α to an electrical angle at which the gear teeth of the gear device 51 come into contact. Specifically, when performing the alignment control using the DC d-axis current, the command angle α is changed by a predetermined angle at a time to perform the alignment control. At this time, it is preferable to determine whether the changed command angle α is an electrical angle at which the teeth of the gear device 51 come into contact, depending on whether the angle detected by the rotation angle sensor 12 follows the angle difference between the command angle α before and after the change. In other words, if the angle detected by the rotation angle sensor 12 follows the angle difference between the command angle α before and after the change, it is considered that the teeth of the gear device 51 do not come into contact, and the command angle α is changed again. In addition, if the angle detected by the rotation angle sensor 12 does not follow the angle difference between the command angle α before and after the change, it is considered that the teeth of the gear device 51 come into contact, and the command angle α is set to the electrical angle θ aligned by the alignment control.

[0103] It is also possible that the command angle α, which is set as the electrical angle at which the gear teeth come into contact, falls outside the predetermined range Ra in which the current value of each phase is equal to or greater than a predetermined threshold value. In such a case, it is advisable to generate torque in the opposite direction of rotation in the rotating electric machine 10, so that the gear teeth come into contact on the opposite side.

[0104] 20 is a flowchart showing a procedure for heat generation control while the vehicle is stopped. This process may be executed by the control device 40 in place of the process shown in FIG.

[0105] In FIG. 20, in step S41, it is determined whether a heat generation request has occurred. For example, if a heat generation request has been received from a higher-level control device, step S41 is answered in affirmative. If a heat generation request has occurred, the process proceeds to the following step S42, and if no heat generation request has occurred, the process ends.

[0106] In step S42, the control mode of the inverter 20 is set to the switching loss increase mode, whereby control of increasing switching loss is appropriately performed in the switching control of the inverter 20 while the vehicle is stopped.

[0107] In step S43, a brake command is output to prevent the wheels of the vehicle from rotating. In the vehicle, for example, an electric parking brake may be operated in response to the brake command.

[0108] Then, in steps S44 and S45, a process is performed to set the command angle α of the rotating motor 10 to the electrical angle at which gear tooth contact occurs in the gear device 51, while performing alignment control to adjust the electrical angle of the rotating motor 10 to the command angle α using a DC d-axis current.

[0109] Specifically, in step S44, the d-axis current command value Id* is set to A1, the q-axis current command value Iq* is set to 0, and the electrical angle θ is set to the command angle α, and the phase current command values ​​Iu*, Iv*, and Iw* are calculated by dq / UVW conversion. In the following step S45, based on the phase current command values ​​Iu*, Iv*, and Iw* calculated in step S44, switching control is performed for the switches 21 and 22 of each phase to control the phase current flowing through each phase of the coil 11. At this time, the command angle α is appropriately changed, and if the angle detected by the rotation angle sensor 12 does not change following the change in the alignment control, it is determined that the changed command angle α is an electrical angle at which tooth contact of the gear device 51 occurs.

[0110] That is, according to steps S44 and S45, the command angle α is set to an electrical angle at which gear teeth contact occurs in the gear device 51, and the phase current command values ​​Iu*, Iv*, Iw* of each phase are set based on the command angle α. Then, the phase currents are controlled by the phase current command values ​​Iu*, Iv*, Iw*.

[0111] Thereafter, in steps S46 and S47, the AC d-axis current is set as the d-axis current command value Id*, and heat generation control is performed using the AC d-axis current. Specifically, in step S46, the d-axis current command value Id* is set to A2·sinφ, and the q-axis current command value Iq* is set to the value calculated using the above (Equation 2). Then, based on the d-axis current command value Id* and the q-axis current command value Iq* and the command angle α (i.e., the command angle α set as the electrical angle at which gear tooth contact occurs), the phase current command values ​​Iu*, Iv*, and Iw* are calculated by dq / UVW conversion.

[0112] In the next step S47, switching control is performed on the switches 21 and 22 of each phase based on the phase current command values ​​Iu*, Iv*, Iw* calculated in step S46, and the phase current flowing through each phase of the coil 11 is controlled. At this time, the control device 40 also performs control of an increase in switching loss. The control of an increase in switching loss may be performed in the same manner as in step S21 of Fig. 15. Briefly, the following processes are performed as appropriate. In the drive circuit 24 of the inverter 20, the gate resistance of each of the switches 21 and 22 is switched to a gate resistance for when loss increases, thereby lengthening the transition time when the switches are turned on and off. When the switches 21 and 22 are turned on and off, the turn-off time is set to be longer than the turn-on time. Of the upper and lower arm switches 21, 22 of the inverter 20, only the upper arm switch 21, which is likely to experience an increase in switching loss due to on / off switching, is switched on and off, and the lower arm switch 22 is not switched on.

[0113] According to steps S46 and S47, torque in one rotational direction is generated in the rotary electric machine 10, and the phase current of each phase is controlled in a state in which the torque does not exceed a predetermined value.

[0114] According to the second embodiment described above, the following effects are achieved in addition to the effects of the first embodiment.

[0115] In a configuration in which the rotation of the rotor of the rotating electric machine 10 is transmitted to the gear device 51, when current control is performed while the vehicle is stopped (when the rotating electric machine 10 is not rotating), it is possible that the rotor rotates in the forward and reverse directions with a small torque, causing gear rattle noise. In consideration of this, current control is performed so that a torque is generated in one direction of the rotation of the rotating electric machine 10 and the absolute value of the torque does not exceed a predetermined value. In this case, while suppressing the rotation of the rotor of the rotating electric machine 10, it is possible to suppress the torque of the rotating electric machine 10 from fluctuating between positive and negative sides across 0. This makes it possible to suppress the continuous generation of gear rattle noise in the gear device 51. In other words, by generating tooth contact in a specific direction in the gear of the gear device 51, it is possible to suppress the inconvenience of the gear rattle noise of the gear device 51 being generated due to the small torque being generated alternately on both positive and negative sides.

[0116] When a small torque is generated in the rotating electric machine 10 while the rotating electric machine 10 is in a stopped state, a brake is applied to suppress the movement of the vehicle. This makes it possible to suppress inconveniences such as the vehicle moving unintentionally.

[0117] When performing alignment control using the DC d-axis current, the electrical angle at which gear teeth contact occurs in the gear device 51 is set as the command angle α, and the phase current command values ​​Iu*, Iv*, Iw* of each phase are set based on the command angle α. This makes it possible to press the teeth of the gear of the gear device 51 in a specific direction, thereby suppressing the occurrence of teeth rattle noise.

[0118] (Other embodiments) The above embodiment may be modified, for example, as follows.

[0119] In the case where the turn-off time of each switch 21, 22 is extended by controlling the increase in switching loss, the dead time may be longer than normal. For example, as shown by the solid line in FIG. 21, when the turn-off time is longer than normal, the timing at which each switch 21, 22 of the upper and lower arms is substantially turned off is delayed, and there is a concern that the upper and lower arms may be short-circuited. In response to this, as shown by the dashed and dotted line in FIG. 21, the timing at which the gate signal is turned off is advanced from ta to tb. In this case, by advancing the timing at which the gate signal is turned off, short-circuiting of the upper and lower arms is suppressed even when the turn-off time is extended. In FIG. 21, the dead time in normal operation is DTa, whereas the dead time when switching loss increases is DTb.

[0120] When the control device 40 lengthens the turn-off time as a control for increasing switching loss, it is preferable to implement feed-forward control in which the voltage command value of each phase is lowered in advance by an amount corresponding to the turn-off delay. For example, as shown in Fig. 22, a correction command unit 81 is provided and, when a heat generation request occurs, the voltage command value of each phase is reduced or corrected by a feed-forward correction term. This makes it possible to appropriately lengthen the dead time when switching loss increases.

[0121] When it is determined that there is a heat generation request, the dead time is made longer than when there is no heat generation request, so that short circuits in the upper and lower arms can be suppressed even if the turn-off time of the switch is longer due to increased switching losses.

[0122] In the first embodiment described above, in the heat generation control of FIG. 15, when a DC d-axis current is caused to flow in the positioning control (steps S17, S18), control of an increase in switching loss is not performed. However, this may be modified so that control of an increase in switching loss is performed when a DC d-axis current is caused to flow in the positioning control (steps S17, S18).

[0123] In each of the above embodiments, the inverter 20 is configured to vary at least one of the turn-on time and the turn-off time of each of the switches 21 and 22 (configuration that increases switching loss) and controls the gate resistance of each of the switches 21 and 22 to be switched, but this may be changed. For example, the gate voltage applied to each of the switches 21 and 22 may be variable. When a heat generation request is generated, the control device 40 sets the gate voltage to a voltage lower than that during normal operation when heat generation control is not generated. This lengthens the time required for charging and discharging the gate in the semiconductor switching element, increasing switching loss.

[0124] In the above embodiments, in the heat generation control by the d-axis current, a sine-wave d-axis current is applied as the AC d-axis current, but this may be changed to a square-wave d-axis current. The AC d-axis current may be any current that flows alternately on both the positive and negative sides at regular intervals.

[0125] The present invention may be applied to other moving objects such as aircraft and ships other than electric vehicles. It may also be applied to stationary systems.

[0126] The control unit and the method described in the present disclosure may be realized by a special-purpose computer provided by configuring a processor and a memory programmed to execute one or more functions embodied in a computer program. Alternatively, the control unit and the method described in the present disclosure may be realized by a special-purpose computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described in the present disclosure may be realized by one or more special-purpose computers configured by a combination of a processor and a memory programmed to execute one or more functions and a processor configured with one or more hardware logic circuits. In addition, the computer program may be stored in a computer-readable non-transitory tangible recording medium as instructions executed by a computer.

[0127] The technical ideas extracted from the above-described embodiments will be described below. [Configuration 1] A control device (40) is applied to a rotating electric machine system including a rotating electric machine (10) having a multi-phase winding (11) and an inverter (20) that adjusts a phase current of each phase in the winding by turning on and off a plurality of switches (21, 22) made of semiconductor switching elements, and controls the on and off of the switches in the inverter, a determination unit that determines whether or not there is a heat generation request in the rotating electrical machine system; a switch control unit that controls the switch when it is determined that there is a heat generation request so that a transition time of at least one of turning on and turning off the switch is longer than a transition time when there is no heat generation request; A control device for a rotating electric machine system comprising: [Configuration 2] 2. The control device for a rotating electric machine system according to configuration 1, wherein, when it is determined that there is a heat generation request, the switch control unit generates a larger switching loss when the switch is turned off than when the switch is turned on. [Configuration 3] 3. The control device for a rotating electric system according to configuration 1 or 2, wherein, when it is determined that there is a heat creation request, the switch control unit sets a transition time when the switch is turned on to the same time as when there is no heat creation request, and sets a transition time when the switch is turned off to a time longer than when there is no heat creation request. [Configuration 4] The inverter has, as the switches, upper arm switches (21) and lower arm switches (22) connected in series for each phase, and has diodes (23) connected in anti-parallel to the semiconductor switching elements in the switches, The control device for a rotating electric system according to any one of configurations 1 to 3, wherein the switch control unit turns on the upper arm switch of any one of the phases to pass a phase current through the winding, and then turns off the upper arm switch to return the phase current, while keeping the lower arm switch of the same phase as the upper arm switch in an off state, thereby returning the phase current through the diode in parallel to the lower arm switch. [Configuration 5] The inverter has, as the switches, upper arm switches (21) and lower arm switches (22) connected in series for each phase, The upper arm switch and the lower arm switch are alternately turned on with a dead time therebetween, The control device for a rotating electric machine system according to any one of configurations 1 to 3, wherein when it is determined that there is a heat creation request, the switch control unit lengthens the dead time compared to when there is no heat creation request. [Configuration 6] A control device in which the on / off of the switch is controlled by a PWM pulse in the inverter, 6. The control device for a rotating electric machine system according to any one of configurations 1 to 5, wherein the switch control unit does not increase switching loss when an on-time of the PWM pulse is shorter than a predetermined time. [Configuration 7] An acquisition unit for acquiring a switch temperature, the switch temperature being a temperature of the switch, 7. The control device for a rotating electric machine system according to any one of configurations 1 to 6, wherein the switch control unit sets a loss increase period during which the transition time is lengthened based on the switch temperature. [Configuration 8] a current control unit that performs current control when it is determined that there is a heat generation request, so that a phase current that changes between positive and negative alternating current flows through each phase of the winding while the rotating electric machine is in a stopped state; The control device for a rotating electric system according to any one of configurations 1 to 7, wherein the switch control unit, when performing current control by the current control unit, controls the transition time in the switch of each phase to be longer than when there is no heat generation request. [Configuration 9] The control device for a rotating electric system according to configuration 8, wherein the current control unit controls the phase current of each phase, which changes in AC on both the positive and negative sides, in a state in which only the d-axis current flows out of the d-axis current and the q-axis current. [Configuration 10] 10. The control device for a rotating electric machine system according to configuration 8 or 9, wherein the switch control unit sets a loss increase period in which the transition time is lengthened based on the magnitude of a phase current flowing through each phase of the winding. [Configuration 11] The rotation of the rotating electric machine is transmitted to a gear of a gear device (51), 9. The control device for a rotating electric machine system according to configuration 8, wherein the current control unit performs current control so as to cause the rotating electric machine to generate torque in one rotational direction and to prevent an absolute value of the torque from exceeding a predetermined value. [Configuration 12] the rotating electric machine is a power source for moving a moving body, A control device for a rotating electric machine system according to configuration 11, comprising a brake command unit that activates a brake to suppress movement of the moving body when a torque in one direction of a rotational direction of the rotating electric machine is generated by the current control of the current control unit. [Configuration 13] The control device for a rotating electric machine system according to any one of configurations 8 to 12, wherein the current control unit performs current control so that, when the rotating electric machine is in a stopped state, all of the phase currents of the windings are equal to or greater than a predetermined threshold value. [Explanation of symbols]

[0128] 10... rotating electric machine, 11... coil, 20... inverter, 21, 22... switches, 40... control device

Claims

1. A control device (40) is applied to a rotating electric machine system including a rotating electric machine (10) having a multi-phase winding (11) and an inverter (20) that adjusts the phase current of each phase in the winding by turning on and off a plurality of switches (21, 22) made of semiconductor switching elements, and controls the on and off of the switches in the inverter, a determination unit that determines whether or not there is a heat generation request in the rotating electrical machine system; a switch control unit that controls the switch when it is determined that there is a heat generation request so that a transition time of at least one of turning on and turning off the switch is longer than that when there is no heat generation request; A control device for a rotating electrical machine system comprising:

2. 2 . The control device for a rotating electrical machine system according to claim 1 , wherein, when it is determined that there is a heat generation request, the switch control unit causes a larger switching loss when the switch is turned off than when the switch is turned on.

3. 2. The control device for a rotating electric system according to claim 1, wherein, when it is determined that there is a heat generation request, the switch control unit sets a transition time when the switch is turned on to be the same as when there is no heat generation request, and sets a transition time when the switch is turned off to be longer than when there is no heat generation request.

4. The inverter has, as the switches, upper arm switches (21) and lower arm switches (22) connected in series for each phase, and has diodes (23) connected in antiparallel to the semiconductor switching elements in the switches, 2. The control device for a rotating electric system according to claim 1, wherein the switch control unit turns on the upper arm switch of any one of the phases to pass a phase current through the winding, and then turns off the upper arm switch to return the phase current, while keeping the lower arm switch of the same phase as the upper arm switch in an off state, thereby returning the phase current via the diode connected in parallel to the lower arm switch.

5. The inverter has, as the switches, upper arm switches (21) and lower arm switches (22) connected in series for each phase, The upper arm switch and the lower arm switch are alternately turned on with a dead time therebetween, The control device for a rotating electrical machine system according to claim 1 , wherein the switch control unit extends the dead time when it is determined that there is a heat generation request, compared to when there is no heat generation request.

6. a control device in which the on / off of the switch is controlled by a PWM pulse in the inverter; 2. The control device for a rotating electrical machine system according to claim 1, wherein the switch control unit does not increase switching loss when the ON time of the PWM pulse is shorter than a predetermined time.

7. an acquisition unit that acquires a switch temperature that is the temperature of the switch; The control device for a rotating electrical machine system according to claim 1 , wherein the switch control unit sets a loss increase period during which the transition time is lengthened based on the switch temperature.

8. a current control unit that performs current control when it is determined that there is a heat generation request, while the rotating electric machine is in a stopped state, so that an AC phase current that changes between positive and negative flows through each phase of the winding; The control device for a rotating electric system according to any one of claims 1 to 7, wherein the switch control unit controls the transition time of the switch of each phase when the current control unit performs current control so that the transition time is longer than when there is no heat generation request.

9. 9. The control device for a rotating electric machine system according to claim 8, wherein the current control unit controls the phase current of each phase, which changes in AC on both positive and negative sides, in a state where only the d-axis current flows out of the d-axis current and the q-axis current.

10. 9. The control device for a rotating electrical machine system according to claim 8, wherein the switch control unit sets a loss increase period during which the transition time is lengthened based on the magnitude of a phase current flowing through each phase of the winding.

11. The rotation of the rotating electric machine is transmitted to a gear of a gear device (51), 9. The control device for a rotating electric machine system according to claim 8, wherein the current control unit controls the current so that the rotating electric machine generates torque in one rotational direction and the absolute value of the torque does not exceed a predetermined value.

12. the rotating electric machine is a power source for movement of a moving body, 12. The control device for a rotating electric machine system according to claim 11, further comprising a brake command unit that activates a brake that suppresses movement of the moving body when torque in one direction of rotation of the rotating electric machine is generated by current control by the current control unit.

13. 9. The control device for a rotating electric machine system according to claim 8, wherein the current control unit performs current control such that, when the rotating electric machine is in a stopped state, all of the phase currents of the windings are equal to or greater than a predetermined threshold value.

14. A current control unit is provided which, when it is determined that there is a heat generation request, performs current control so that phase currents that change alternating current on both the positive and negative sides flow through each phase of the winding while the vehicle on which the rotating electric machine is mounted is in a stopped state, The control device for a rotating electric system according to any one of claims 1 to 7, wherein the switch control unit controls the transition time of the switch of each phase when the current control unit performs current control so that the transition time is longer than when there is no heat generation request.

15. A control program applied to a rotating electric machine system including a rotating electric machine (10) having a multi-phase winding (11) and an inverter (20) that adjusts a phase current of each phase in the winding by turning on and off a plurality of switches (21, 22) made of semiconductor switching elements, the control program being executed by a control device that controls the on and off of the switches in the inverter, a determination process for determining whether or not there is a heat generation request in the rotating electrical machine system; a switch control process for controlling the switch when it is determined that there is a heat generation request so that a transition time of at least one of turning on and turning off the switch is longer than that when there is no heat generation request; A control program that executes the above.

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