Control device for AC rotating motor

Abstract

The present invention provides a control device for an AC rotating motor, which can suppress the temperature rise of a switching element caused by the passage of a large current and can perform overheat protection below a limit temperature. The control device comprises: a switching element temperature acquisition unit (31) for acquiring the temperature of a switching element (19a-19c, 20a-20c); a switching element temperature compensation value calculation unit (30) for calculating a compensation value based on the state quantity of the AC rotating motor (18) acquired by an AC rotating motor state quantity acquisition unit (29); and an allowable torque adjustment unit (32, 32a, 32b) for adjusting the allowable torque of the AC rotating motor (18) so that the sum of the switching element temperature and the compensation value does not exceed the limit temperature of the switching element (19a-19c, 20a-20c).

Description

Technical Field

[0001] The present application relates to a control device for an AC rotating electric machine. Background Art

[0002] Generally, an electric vehicle such as an electric vehicle or a hybrid vehicle is equipped with an AC rotating motor for driving the vehicle or recovering the deceleration energy of the vehicle. The AC rotating motor is connected to a power conversion circuit having a switching element, which converts the DC power of a DC power source (battery) into AC power, or converts the AC power generated by the AC rotating motor into DC power. The switching element mentioned here is a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) or an IGBT (Insulated Gate Bipolar Transistor).

[0003] Usually, the switch element is set with a temperature that must not be exceeded - a limit temperature. Once the temperature is exceeded, it is likely to be damaged. Therefore, a control of overheat protection is proposed to prevent the switch element from exceeding the limit temperature of the switch element.

[0004] For example, according to the conventional power conversion device disclosed in Patent Document 1, a method is proposed for correcting the torque command value of the AC rotating electric machine when the temperature of the power semiconductor is above a set temperature so that the temperature of the power semiconductor matches the set temperature.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent No. 6107936 Summary of the invention

[0008] Technical problem to be solved by the invention

[0009] Generally, permanent magnet synchronous motors are widely used as AC rotating motors driven by inverters. The torque of a permanent magnet synchronous motor is determined by the magnetic force of the rotor and the current that energizes the stator coil, and the magnetic force of the rotor is determined by the type or structure of the magnet. Therefore, the torque of an AC rotating motor is controlled by the current that energizes the stator coil. In other words, the greater the current that energizes the stator coil, the greater the torque that the permanent magnet synchronous motor can obtain. In addition, when the speed of the AC rotating motor is constant, the permanent magnet synchronous motor can obtain a larger output.

[0010] However, the current that can be passed through an AC rotating electric machine such as a permanent magnet synchronous motor is generally determined by the specifications of the switching element used in the power conversion circuit or the cooling performance for cooling the switching element. This is because, as mentioned above, the switching element has a limit temperature, and if this temperature is exceeded, it may be damaged.

[0011] The temperature rise of the switching element caused by energization can be calculated by multiplying the loss of the switching element caused by energization and the thermal resistance from the switching element to the cooling medium. The loss of the switching element is positively correlated with the current energized, and the thermal resistance from the switching element to the cooling body has a first-order delayed response. Therefore, even if the same current is energized, if the energization time is different, the temperature rise of the switching element will be different. In other words, even if the temperature rise of the switching element is the same, if the time is shorter, the greater the current that can be energized, the greater the output that can be obtained.

[0012] In the use of AC rotating motors used in electric vehicles such as electric vehicles and hybrid vehicles, there are cases where a large current is output for a short period of time. This is when starting the engine or recovering regenerative energy during deceleration. In this case, a large current needs to be supplied to the AC rotating motor, and the temperature of the switching element may exceed the limit temperature immediately after the torque command is issued.

[0013] In the above-mentioned Patent Document 1, it is proposed to control the switching element temperature to match the set temperature when the switching element temperature reaches or exceeds the set temperature. However, when a large torque is applied instantaneously, the temperature of the switching element may overshoot and exceed the limit temperature. In addition, if the set temperature of the switching element is set low in anticipation of the overshoot and exceeding the limit temperature of the switching element, the current supplied to the AC rotating electric machine will decrease, resulting in excessively low output.

[0014] The present application discloses a technology for solving the above-mentioned problems, and its purpose is to provide a control device for an AC rotating electric machine, which can suppress the temperature rise of a switching element caused by the passage of a large current and can perform overheat protection below a limit temperature.

[0015] Technical means for solving technical problems

[0016] The control device of the AC rotating motor disclosed in the present application is characterized in that it includes: a switching element temperature acquisition unit, which acquires temperature information of a switching element connected to a power conversion circuit for driving the AC rotating motor; an AC rotating motor state quantity acquisition unit, which acquires the state quantity of the AC rotating motor; a switching element temperature compensation value calculation unit, which calculates a compensation value for the temperature of the switching element based on the state quantity of the AC rotating motor; and an allowable torque adjustment unit, which adjusts the torque that can be output by the AC rotating motor so that the sum of the temperature information of the switching element acquired by the switching element temperature acquisition unit and the compensation value calculated by the switching element temperature compensation value calculation unit does not exceed a preset limit temperature of the switching element.

[0017] Effects of the Invention

[0018] According to the control device for an AC rotating electric machine disclosed in the present application, it is possible to provide a control device for an AC rotating electric machine that can suppress a temperature rise of a switching element due to passage of a large current and can perform overheat protection at a temperature below a limit temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a configuration diagram of a control device for an AC rotating electric machine according to the first embodiment.

[0020] Figure 2 This is a flowchart for explaining the operation of the control device for the AC rotating electric machine according to the first embodiment.

[0021] Figure 3 It is a diagram showing different configurations of the overheat protection and torque command unit in the control device for the AC rotating electric machine according to the first embodiment.

[0022] Figure 4 1 is a diagram showing a first example of change in the compensation value in the switching element temperature compensation value calculation unit of the control device for the AC rotating electric machine according to the first embodiment.

[0023] Figure 5 1 is a diagram showing a second example of change in the compensation value in the switching element temperature compensation value calculation unit of the control device for the AC rotating electric machine according to the first embodiment.

[0024] Figure 6 This is a diagram for explaining a method of determining a predetermined value in a switching element temperature compensation value calculation unit of the control device for the AC rotating electric machine according to the first embodiment.

[0025] Figure 7 This is a diagram of Example 1 when the control device for the AC rotating electric machine according to the first embodiment detects the temperature of the switching element.

[0026] Figure 8 This is a diagram of Example 2 when the control device for the AC rotating electric machine according to the first embodiment detects the temperature of the switching element.

[0027] Fig. 9 This is a diagram showing a change example for explaining the relationship between the switching element temperature obtained by the control device for the AC rotating electric machine according to the first embodiment using the temperature detection element and the actual switching element temperature.

[0028] Fig.10 This is a configuration diagram showing an example of a maximum current adjustment unit in the control device for the AC rotating electric machine according to the first embodiment.

[0029] Fig.11 This is a diagram for explaining a method of calculating the allowable torque upper limit value in the allowable torque calculation unit of the control device for the AC rotating electric machine according to the first embodiment.

[0030] Fig.12 This is a diagram for explaining a method for calculating the allowable torque lower limit value in the allowable torque calculation unit of the control device for the AC rotating electric machine according to the first embodiment.

[0031] Fig.13 This is a diagram showing the operation of the control device for the AC rotating electric machine according to the first embodiment when the temperature of the switching element is controlled.

[0032] Fig.14 This is a diagram showing the operation of a conventional AC rotating electric machine control device when performing temperature control of a switching element.

[0033] Fig.15 This is a diagram showing a further different configuration of the overheat protection and torque command unit in the control device for the AC rotating electric machine according to the first embodiment.

[0034] Fig.16 This is a diagram showing an example of the change in compensation value in a switching element temperature compensation value calculation unit of the control device for the AC rotating electric machine according to the second embodiment.

[0035] Fig.17 This is a diagram showing a further different configuration of the overheat protection and torque command unit in the control device for the AC rotating electric machine according to the first embodiment.

[0036] Fig.18 1 is a diagram showing an example of change in compensation value in a switching element temperature compensation value calculation unit of the control device for an AC rotating electric machine according to the third embodiment.

[0037] Fig.19 This is a diagram showing a further different configuration of the overheat protection and torque command unit in the control device for the AC rotating electric machine according to the first embodiment.

[0038] Fig. 20 1 is a diagram showing an example of change in compensation value in a switching element temperature compensation value calculation unit of the control device for an AC rotating electric machine according to the fourth embodiment.

[0039] Fig.21 It is a diagram showing different configurations of the overheat protection and torque command unit in the control device for the AC rotating electric machine according to the first embodiment.

[0040] Fig. 22 1 is a diagram showing an example of a configuration of a permissible torque control amount calculation unit of a control device for an AC rotating electric machine according to a fifth embodiment.

[0041] Fig.23 1 is a diagram showing an example of a configuration of an allowable torque calculation unit of a control device for an AC rotating electric machine according to a fifth embodiment.

[0042] Fig.24 This is a diagram for explaining a method of calculating the allowable torque upper limit value in the allowable torque calculation unit of the control device for the AC rotating electric machine according to the fifth embodiment.

[0043] Fig.25 This is a diagram for explaining a method for calculating the allowable torque lower limit value in the allowable torque calculation unit of the control device for the AC rotating electric machine according to the fifth embodiment. DETAILED DESCRIPTION

[0044] Hereinafter, preferred embodiments of the control device for an AC rotating electric machine according to the present application will be described with reference to the drawings.

[0045] Implementation method 1.

[0046] Figure 1 1 is a block diagram of a control device for an AC rotating electric machine according to Embodiment 1. Figure 1 As shown, the control device of the AC rotating electric machine includes a DC power supply 10, a voltage detection unit 11, an inverter 12, a magnetic pole position detection unit 13, an electrical angular velocity calculation unit 14, current sensors 15a~15c, an inverter control unit 16, and an overheat protection and torque command unit 17, and the control device of the AC rotating electric machine controls the AC rotating electric machine 18.

[0047] The control device for the AC rotating electric machine according to the first embodiment is configured as described above, and the configuration of each portion thereof will be described below.

[0048] The DC power supply 10 is a chargeable and dischargeable power supply, and performs power transfer with the AC rotating electric machine 18 via the inverter 12. The DC power supply 10 has a high voltage side node P and a low voltage side node N. A boost converter may be provided between the high voltage side node P of the DC power supply 10 and the inverter 12, and the DC voltage provided by the DC power supply 10 may be boosted by DC / DC conversion. In addition, a filter capacitor for filtering the DC voltage may be connected between the high voltage side node P and the low voltage side node N.

[0049] The voltage detection unit 11 detects the DC voltage Vdc of the DC power supply 10. Specifically, the voltage detection unit 11 measures the inter-terminal voltage between the high voltage side node P and the low voltage side node N, and outputs it as the DC voltage Vdc.

[0050] like Figure 1 As shown, the inverter 12 includes switching elements 19a to 19c on the upper arm side and switching elements 20a to 20c on the lower arm side. The inverter 12 converts the DC voltage from the DC power supply 10 into an AC voltage through DC / AC conversion by using the switching operation of the switching elements 19a to 19c on the upper arm side and the switching elements 20a to 20c on the lower arm side. Then, the obtained AC voltage is applied to the AC rotating motor 18.

[0051] In the inverter 12, the rectifier elements D1 to D3, D4 to D6 are respectively connected in reverse parallel to the switching elements 19a to 19c on the upper arm side and the switching elements 20a to 20c on the lower arm side. When the switching elements 19a to 19c, 20a to 20c are MOSFETs, the rectifier elements exist inside the MOSFETs themselves. On the other hand, IGBTs can be used as the switching elements 19a to 19c, 20a to 20c, and as a connection method of the switching element and the rectifier element in this case, for example, the cathode electrode of the rectifier element is connected to the collector electrode of the switching element, and the anode electrode of the rectifier element is connected to the emitter electrode of the switching element.

[0052] The AC rotating motor 18 is applied with the AC voltage output by the inverter 12, thereby controlling the driving force and braking force of the vehicle. The AC rotating motor 18 is composed of, for example, a permanent magnet synchronous motor. In the present embodiment, as the AC rotating motor 18, an AC rotating motor having a three-phase armature winding is used as an example for explanation. However, the number of phases of the AC rotating motor 18 is not limited to three phases, but can be set to any number of phases. That is, the control device of the present embodiment is applicable to an AC rotating motor having a multi-phase armature winding.

[0053] The magnetic pole position detection unit 13 detects the magnetic pole position of the AC rotating motor 18. The magnetic pole position detection unit 13 includes a Hall element, a rotary transformer, or an encoder. The magnetic pole position detection unit 13 detects the rotation angle of the magnetic pole of the rotor of the AC rotating motor 18 relative to the reference rotation position, and outputs a signal indicating the detection value of the detected rotation angle as the magnetic pole position θ. Here, the magnetic pole position θ indicates the rotation angle of the q-axis. In addition, the reference rotation position of the rotor is appropriately set in advance at an arbitrary position.

[0054] The electrical angular velocity calculation unit 14 calculates the electrical angular velocity ω using the magnetic pole position θ output from the magnetic pole position detection unit 13. The electrical angular velocity calculation unit 14 may be configured to directly detect the electrical angular velocity ω of the AC rotating electric machine 18 using a Hall element, an encoder, or the like.

[0055] The current sensors 15a to 15c detect the current amounts iU, iV, and iW flowing through the U-phase, V-phase, and W-phase of the AC rotating electric machine 18, respectively, and output them to the three-phase to two-phase current conversion unit 21. Figure 1 In the embodiment, three current sensors 15a to 15c are provided to detect the current of each of the U phase, the V phase, and the W phase, but the present invention is not limited thereto, and the number of current sensors may be 2. In this case, the current is detected only in two phases, and the current of one phase is calculated based on the detected currents of the two phases.

[0056] The inverter control unit 16 controls the switching operations of the switching elements 19a to 19c on the upper arm side and the switching elements 20a to 20c on the lower arm side included in the inverter 12, thereby adjusting the potentials of the connection nodes Uac, Vac, and Wac between the inverter 12 and the AC rotating electric machine 18, thereby controlling the amount of current flowing through the AC rotating electric machine 18. The configuration of the inverter control unit 16 will be described below.

[0057] like Figure 1 As shown in FIG. 1 , the inverter control unit 16 includes a current command operation unit 22, a d-axis current controller 23, a q-axis current controller 24, a two-phase to three-phase voltage conversion unit 25, a PWM (pulse width modulation) circuit 26, a gate driver 27, and a three-phase to two-phase current conversion unit 21. The inverter control unit 16 controls the inverter 12 by using dq vector control, thereby performing rotation control of the AC rotating electric machine 18. The following describes the components constituting the inverter control unit 16.

[0058] The adjusted torque command value Ctrq_adj for commanding the torque generated in the AC rotating electric machine 18 is inputted from the torque command adjustment unit 28 of the overheat protection and torque command unit 17 to the current command operation unit 22. The current command operation unit 22 calculates the d-axis current command value Cid and the q-axis current command value Ciq based on the torque command value Ctrq_adj, and outputs them to the d-axis current controller 23 and the q-axis current controller 24.

[0059] The three-phase-to-two-phase current conversion unit 21 converts the three-phase current amounts iU, iV, and iW from the current sensors 15a to 15c into two-phase current amounts, namely, the d-axis current value id and the q-axis current value iq, based on the magnetic pole position θ from the magnetic pole position detection unit 13. The converted d-axis current value id is subtracted from the d-axis current command value Cid, and the subtraction result is input to the d-axis current controller 23. In addition, the converted q-axis current value iq is subtracted from the q-axis current command value Ciq, and the subtraction result is input to the q-axis current controller 24.

[0060] The d-axis current controller 23 calculates the DC d-axis voltage command value Cvd so that the deviation between the d-axis current command value Cid from the current command calculation unit 22 and the d-axis current value id from the three-phase-to-two-phase current conversion unit 21 becomes "0", and outputs the DC d-axis voltage command value Cvd to the two-phase-to-three-phase voltage conversion unit 25.

[0061] The q-axis current controller 24 calculates the DC q-axis voltage command value Cvq so that the deviation between the q-axis current command value Ciq from the current command calculation unit 22 and the q-axis current value iq from the three-phase-to-two-phase current conversion unit 21 becomes "0", and outputs the DC q-axis voltage command value Cvq to the two-phase-to-three-phase voltage conversion unit 25.

[0062] The two-phase to three-phase voltage converter 25 converts the two-phase DC d-axis voltage command value Cvd and the q-axis voltage command value Cvq into three-phase AC voltage command values ​​Cvu, Cvv and Cvw based on the magnetic pole position θ from the magnetic pole position detector 13 , and outputs them to the PWM circuit 26 .

[0063] The PWM circuit 26 generates control signals UH, UL, VH, VL, WH, and WL for controlling the switching elements 19 a to 19 c , 20 a to 20 c included in the inverter 12 , and outputs them to the gate driver 27 .

[0064] The gate driver 27 controls the switching operations of the switching elements 19 a to 19 c and 20 a to 20 c based on the respective control signals from the PWM circuit 26 , and performs DC / AC conversion in the inverter 12 .

[0065] The overheat protection and torque command unit 17 includes an AC rotating electric machine state quantity acquisition unit 29, a switching element temperature compensation value calculation unit 30, a switching element temperature acquisition unit 31, an allowable torque adjustment unit 32, and a torque command adjustment unit 28, and performs overheat protection of the switching elements 19a to 19c, 20a to 20c and adjustment of the torque command. The allowable torque adjustment unit 32 is composed of a control amount adjustment unit 33 and an allowable torque calculation unit 34. The following describes the components that constitute the overheat protection and torque command unit 17.

[0066] The AC rotating motor state quantity acquisition unit 29 acquires the state quantity of the AC rotating motor 18 as a control target. As a specific state quantity, any one or two or more of the detected amount of current energizing the AC rotating motor 18, the command amount of current energizing the AC rotating motor 18, the estimated amount of torque output by the AC rotating motor 18, and the command amount of torque output by the AC rotating motor 18 can be used. The acquired state quantity of the AC rotating motor 18 is output to the switching element temperature compensation value calculation unit 30.

[0067] The switching element temperature compensation value calculation unit 30 calculates a compensation value of zero or a positive value based on the state quantity from the AC rotating electric machine state quantity acquisition unit 29. The calculated compensation value is output as a switching element temperature compensation value. The specific operation of the switching element temperature compensation value calculation unit 30 will be described later.

[0068] The switching element temperature acquisition unit 31 acquires the temperature of the switching elements 19a to 19c, 20a to 20c of the inverter 12. As a method for acquiring the temperature of the switching elements 19a to 19c, 20a to 20c, for example, a temperature detection element whose output voltage changes in proportion to the temperature is set on the same substrate as the switching elements 19a to 19c, 20a to 20c, and the temperature of the switching elements 19a to 19c, 20a to 20c is acquired by measuring the output voltage of the temperature detection element and converting it to temperature. Alternatively, the temperature rise value of the switching elements 19a to 19c, 20a to 20c generated in each operation mode can be obtained by multiplying the loss of the switching elements 19a to 19c, 20a to 20c by the thermal resistance between the switching elements 19a to 19c, 20a to 20c and the cooling body, and the estimated value of the switching element temperature can be obtained based on the sum of the temperature rise value and the temperature of the cooling body. Since the algorithm for estimating the temperature of the switching elements 19a to 19c and 20a to 20c is well known, a detailed description thereof will be omitted here. Alternatively, the temperature of the switching elements 19a to 19c and 20a to 20c may be estimated using another estimation algorithm.

[0069] The control amount adjustment unit 33 adjusts the control amount of the AC rotating motor 18 and outputs the adjusted control amount Cadj. The control amount adjustment unit 33 limits the control amount of the AC rotating motor 18 so that the sum of the switching element temperature and the switching element temperature compensation value does not exceed the preset limit temperature of the switching elements 19a~19c, 20a~20c. In this way, the overshoot of the switching element temperature of the inverter 12 relative to the preset limit temperature is suppressed, and the switching elements 19a~19c, 20a~20c can be prevented from being damaged due to overheating. Here, the control amount of the AC rotating motor 18 refers to the control amount for limiting the maximum value of the current or the allowable torque for energizing the AC rotating motor 18. The specific structure and operation of the control amount adjustment unit 33 will be described later.

[0070] The allowable torque calculation unit 34 calculates the allowable torque Ctrq_alw based on the adjusted control amount Cadj output from the control amount adjustment unit 33. The calculation method of the allowable torque Ctrq_alw in the allowable torque calculation unit 34 will be described later.

[0071] The torque command adjustment unit 28 adjusts the torque command value Ctrq of the AC rotating electric machine 18 so as to be within the range of the allowable torque Ctrq_alw output from the allowable torque calculation unit 34. The torque command adjustment unit 28 outputs the adjusted torque command value Ctrq_adj to the current command calculation unit 22.

[0072] Next, we will use Figure 2 Flowchart Description Figure 1 The operation flow in the overheat protection and torque command unit 17 is shown in FIG.

[0073] First, in step S100, start Figure 1 Controls of the control device shown.

[0074] Next, in step S101 , the limit temperatures of the switching elements 19 a to 19 c and 20 a to 20 c are acquired. Then, the process proceeds to step S102 .

[0075] In step S102, the temperatures of the switching elements 19a to 19c and 20a to 20c are acquired by the switching element temperature acquisition unit 31. Then, the process proceeds to step S103.

[0076] In step S103, the state quantity of the AC rotating electric machine 18 is acquired from the AC rotating electric machine state quantity acquisition unit 29. Then, the process proceeds to step S104.

[0077] In step S104, a compensation value for the switching element temperature is calculated based on the state quantity output from the AC rotating electric machine state quantity acquisition unit 29. Then, the process moves to step S105.

[0078] In step S105 , the sum of the switching element temperature obtained in step S102 and the compensation value calculated in step S104 is calculated by an adder to obtain the compensated switching element temperature. Then, the process proceeds to step S106 .

[0079] In step S106, a temperature deviation ΔT between the compensated switching element temperature calculated in step S105 and the limit temperature of the switching elements 19a to 19c and 20a to 20c obtained in step S101 is calculated by a subtractor. Then, the process proceeds to step S107.

[0080] In step S107, the control amount adjustment unit 33 adjusts the control amount based on the temperature deviation ΔT calculated in step S106 so that the compensated switching element temperature calculated in step S105 does not exceed the limit temperature of the switching elements 19a to 19c, 20a to 20c acquired in step S101, thereby obtaining the control amount Cadj. Then, the process proceeds to step S108.

[0081] In step S108 , the upper limit value Ctrq_alw_upper of the permissible torque and the lower limit value Ctrq_alw_lower of the permissible torque are calculated based on the control amount Cadj in step S107 . Then, the process proceeds to step S109 .

[0082] In step S109, a torque command value Ctrq for instructing the AC rotating electric machine 18 is acquired. Then, the process proceeds to step S110.

[0083] In step S110, the upper limit value Ctrq_alw_upper of the permissible torque calculated in step S108 is compared with the torque command value Ctrq obtained in step S109. When the torque command value Ctrq> the upper limit value Ctrq_alw_upper of the permissible torque is established, go to "Yes" and execute step S112, and when the torque command value Ctrq> the upper limit value Ctrq_alw_upper of the permissible torque is not established, go to "No" and execute step S111.

[0084] In step S111, the lower limit value Ctrq_alw_lower of the permissible torque calculated in step S108 is compared with the torque command value Ctrq obtained in step S109. When the torque command value Ctrq < the lower limit value Ctrq_alw_lower of the permissible torque is established, go to "Yes" and execute step S113, and when the torque command value Ctrq < the lower limit value Ctrq_alw_lower of the permissible torque is not established, go to "No" and execute step S114.

[0085] In step S112, the adjusted torque command value Ctrq_adj is set to the upper limit value Ctrq_alw_upper of the allowable torque calculated in step S108. Then, the process proceeds to step S115.

[0086] In step S113 , the adjusted torque command value Ctrq_adj is set to the lower limit value Ctrq_alw_lower of the allowable torque calculated in step S108 . Then, the process proceeds to step S115 .

[0087] In step S114, the adjusted torque command value Ctrq_adj is set as the torque command value Ctrq acquired in step S109. Then, the process proceeds to step S115.

[0088] In step S115, a series of operations are ended.

[0089] In this order, the torque control of the AC rotating electric machine 18 having the overheat protection function of the switching elements 19a to 19c and 20a to 20c is performed.

[0090] Next, the state quantity of the AC rotating electric machine 18 is taken as the phase current detection value, and the control quantity is taken as the maximum current value. Figure 3 Detailed description Figure 1 The overheat protection and torque command unit 17 shown in FIG.

[0091] exist Figure 3 in Figure 1 In the overheat protection and torque command unit 17 shown in FIG. 1 , the AC rotating motor state quantity acquisition unit 29 is replaced by a phase current detection value calculation unit 29a, and the control quantity adjustment unit 33 is replaced by a maximum current adjustment unit 33a, so as to serve as the overheat protection and torque command unit 17a. Figure 3 The replacement shown is an example, and as described above, the state amount of the AC rotating electric machine 18 may be a phase current command value, a torque estimation value, or a torque command value, and the control amount may be a control amount for limiting the allowable torque. Figure 3 In the case of Figure 3 In the figure, reference numeral 30a indicates a switching element temperature compensation value calculation unit, reference numeral 32a indicates an allowable torque adjustment unit, and reference numeral 34a indicates an allowable torque calculation unit. Figure 1 The actions are the same as the instructions in the Actions section.

[0092] The phase current detection value calculation unit 29a calculates the effective value iuvw_rms of the phase current that energizes the AC rotating electric machine 18 using the d-axis current value id and the q-axis current value iq converted by the three-phase to two-phase current conversion unit 21. The calculated effective value iuvw_rms of the phase current is output as the phase current detection value to the switching element temperature compensation value calculation unit 30a.

[0093] The switching element temperature compensation value calculation unit 30a calculates a compensation value of zero or a positive value based on the phase current detection value iuvw_rms from the phase current detection value calculation unit 29a, and outputs the calculated compensation value as the switching element temperature compensation value.

[0094] Here, a method of calculating the switching element temperature compensation value based on the phase current detection value iuvw_rms will be described.

[0095] Figure 4 A first example of change in the switching element temperature compensation value for the phase current detection value iuvw_rms is shown.

[0096] Figure 4 The horizontal axis represents the phase current detection value iuvw_rms, and the vertical axis represents the switching element temperature compensation value. Figure 4 In the embodiment, when the phase current detection value iuvw_rms is less than a predetermined value, that is, less than a predetermined phase current detection value Ia, the switching element temperature compensation value is calculated to be "0". On the other hand, when the phase current detection value iuvw_rms is greater than the predetermined phase current detection value Ia, a compensation value proportional to the phase current detection value iuvw_rms is calculated using the upper limit value Tcu of the switching element temperature compensation value as the upper limit.

[0097] For the temperature compensation value of the switching element, such as Figure 5 As shown in the second variation example, the compensation value for the phase current detection value iuvw_rms can be calculated into a curve. Figure 4 and Figure 5 The phase current detection value Ib in is set to the maximum phase current effective value that can flow in the AC rotating electric machine 18 during control.

[0098] Next, based on Figure 6 illustrate Figure 4 and Figure 5 The specified phase current detection value Ia and the upper limit value Tcu of the switching element temperature compensation value.

[0099] Figure 6 2 is a graph showing the relationship between the switching element temperature and the phase current detection value. Generally, when the current flowing through the AC rotating electric machine 18 increases, the switching element temperature increases.

[0100] Figure 6 Tch in the figure is the limit temperature that the switching elements 19a to 19c, 20a to 20c must not exceed in terms of specifications. The specified phase current detection value Ia is the current value at which the switching element temperature reaches the limit temperature Tch when the switching element temperature compensation value calculation unit 30a does not perform compensation. In other words, the specified phase current detection value Ia is the maximum phase current detection value that will not exceed the limit temperature Tch of the switching elements 19a to 19c, 20a to 20c even without compensation by the switching element temperature compensation value calculation unit 30a.

[0101] Figure 6 Tmax in the figure represents the temperature reached by the switching elements 19a to 19c, 20a to 20c when the AC rotating motor 18 is energized with the maximum phase current effective value Ib that can be energized. This temperature Tmax is usually higher than the limit temperature Tch of the switching elements 19a to 19c, 20a to 20c, and is expressed as Tmax = Tch + α. α when expressed in this way is set to the upper limit value Tcu of the switching element temperature compensation value. In other words, it is set to the minimum value α of the temperature drop required for the switching element temperature to be lower than the limit temperature Tch of the switching elements 19a to 19c, 20a to 20c when the AC rotating motor 18 is energized with the maximum phase current effective value Ib that can be energized.

[0102] Regarding the overheat protection of the switching elements 19a to 19c and 20a to 20c, the following matters should be noted.

[0103] Since there is a significant deviation between the switch element temperature obtained from the temperature detection element and the actual switch element temperature, the actual switch element temperature may be higher than the temperature information obtained by the temperature detection element. In this case, since it is not the switch element temperature obtained by the temperature detection element that needs to be protected, but the actual switch element temperature with a higher temperature, overheat protection must be performed so that the actual switch element temperature becomes below the limit temperature.

[0104] Next, use Figure 7 and Figure 8 An example in which there is a deviation between the switching element temperature obtained from the temperature detection element and the actual switching element temperature will be described.

[0105] When the temperature detection element is mounted on the same substrate as the switching elements 19a to 19c and 20a to 20c in order to detect the temperature of the switching element, as shown in FIG. Figure 7 and Figure 8 As shown, it is considered that a temperature detection element 50 is provided.

[0106] Figure 7This is the case where the temperature detection element 50 is located at a corner portion of the substrate 51 on which the switching elements 19a to 19c and 20a to 20c are arranged. Figure 8 The temperature detection element 50 is located at the center of the substrate 51 on which the switching elements 19a to 19c and 20a to 20c are arranged. Figure 7 and Figure 8 When the effective area 52 of the switching elements 19a to 19c and 20a to 20c can be mounted, Figure 7 In this way, when the temperature detection element 50 is located at the corner of the substrate 51 on which the switching elements 19a to 19c and 20a to 20c are provided, the effective area 52 on which the switching elements 19a to 19c and 20a to 20c can be provided larger.

[0107] The reason is that Figure 8 Compared with the configuration of Figure 7 The configuration does not require a lot of area for wiring. When the area where the switching elements 19a to 19c and 20a to 20c can be mounted is large, that is, Figure 7 In the case of configuration, with Figure 8 However, on the substrate 51 on which the switching elements 19a to 19c, 20a to 20c are arranged, the area where the temperature is most likely to rise is near the center 53 of the substrate 51 on which the switching elements 19a to 19c, 20a to 20c are arranged. Therefore, when using Figure 7 In the case of the arrangement of the temperature detection element 50 shown, a difference occurs between the highest temperature of the switching elements 19 a to 19 c and 20 a to 20 c and the temperature detected by the temperature detection element 50 .

[0108] Fig. 9 It is shown in Figure 7 The diagram showing an example of time transition of the actual switching element temperature A and the switching element temperature B obtained by the temperature detection element 50 in the arrangement of the temperature detection element 50 shown shows the temperature when a certain loss occurs in the switching elements 19a to 19c and 20a to 20c, respectively.

[0109] As described above, the actual switching element temperature A evolves at a higher temperature than the switching element temperature B obtained by the temperature detection element 50. The reason for this is that there are thermal resistance and thermal capacitance between the center vicinity 53 and the temperature detection element 50. Therefore, the temperature of the switching element temperature obtained by the temperature detection element 50 has a delay relative to the temperature rise of the actual switching element temperature, and has a temperature difference that changes with time.

[0110] Next, return Figure 3 The maximum current adjustment unit 33 a will be described.

[0111] The maximum current adjustment unit 33a adjusts the maximum current Imax based on the temperature deviation ΔT between the compensated temperature of the switching elements and the limit temperature of the switching elements 19a to 19c, 20a to 20c, and outputs the adjusted maximum current Imax_adj. Figure 1 The adjusted control amount Cadj in is replaced by the adjusted maximum current Imax_adj. The adjusted maximum current Imax_adj represents the maximum current value allowed at the current moment with respect to the absolute value of the phase current represented by the following equation.

[0112]

[0113] The maximum current adjustment unit 33a adjusts the value of the maximum current Imax so that the temperature of the switching element after compensation does not exceed the preset limit temperature of the switching elements 19a-19c, 20a-20c. In this way, the temperature of the switching element of the inverter 12 can be suppressed from overshooting relative to the preset limit temperature, and the switching elements 19a-19c, 20a-20c can be prevented from being damaged due to overheating.

[0114] Fig.10 An example of the structure of the maximum current adjustment unit 33a is shown in FIG. Fig.10 In the structural example of, the maximum current adjustment unit 33a includes a proportional adjustment unit 54, an integral adjustment unit 55, an adder 56, and an upper and lower limit unit 57. The temperature deviation ΔT between the preset limit temperature and the temperature after the switching element compensation is input to the maximum current adjustment unit 33a. The temperature deviation ΔT is a value obtained by subtracting the temperature after the switching element compensation from the limit temperature. Therefore, when the temperature after the switching element compensation exceeds the limit temperature, the value of the temperature deviation ΔT becomes a negative value. Therefore, in this case, the higher the temperature after the switching element compensation is, the smaller the value of the temperature deviation ΔT is.

[0115] exist Fig.10 In the configuration example of , the proportional gain Kpa of the proportional regulator 54 is a positive value. The proportional regulator 54 outputs a value obtained by multiplying the input deviation by the proportional gain Kpa.

[0116] exist Fig.10 In the structural example, the initial value of the integral regulator 55 is used as the "upper limit value of the maximum current Imax", and the output of the proportional regulator 54 is integrated. The "upper limit value of the maximum current Imax" refers to the value when the "absolute value of the phase current" represented by the above formula is calculated using the designed maximum d-axis current and the maximum q-axis current. In other words, no matter what the conditions are, a current of an "absolute value of the phase current" greater than the "upper limit value of the maximum current Imax" will not be intentionally allowed to flow. On the other hand, the maximum current Imax is a variable amount, and is adjusted between "0" and the "upper limit value of the maximum current Imax".

[0117] exist Fig.10 In the structural example, when the temperature of the switching element after compensation becomes higher than the limit temperature, the output of the proportional adjuster 54 becomes a negative value, and the output of the integral adjuster 55 decreases accordingly. Specifically, when the temperature of the switching element after compensation is higher than the limit temperature, the temperature deviation ΔT becomes a negative value. The proportional adjuster 54 outputs a value obtained by multiplying the deviation by the proportional gain Kpa. Therefore, when the temperature deviation ΔT is a negative value, the output of the proportional adjuster 54 becomes a negative value. In addition, since the integral adjuster 55 integrates negative values, the output of the integral adjuster 55 gradually decreases from the initial value. On the other hand, when the temperature of the switching element after compensation is below the limit temperature, the output of the proportional adjuster 54 becomes a positive value, and the output of the integral adjuster 55 increases accordingly. Fig.10 In the configuration example, the output of the proportional adjuster 54 and the output of the integral adjuster 55 are added by the adder 56. The output of the adder 56 becomes the output value of the proportional adjustment and the integral adjustment. Thus, the proportional adjustment and the integral adjustment are performed on the temperature deviation ΔT by the proportional adjuster 54 and the integral adjuster 55.

[0118] exist Fig.10 In the configuration example, the upper and lower limit limiting unit 57 then performs upper and lower limit limiting on the output values ​​of the proportional adjustment and the integral adjustment. The upper and lower limit limiting unit 57 sets the upper limit value to the "upper limit value of the maximum current Imax" and sets the lower limit value to "0". The upper and lower limit limiting unit 57 performs upper and lower limit limiting on the output values ​​of the proportional adjustment and the integral adjustment by using the upper and lower limit values, thereby calculating the adjusted maximum current Imax_adj.

[0119] Specifically, the addition result of the output of the proportional adjuster 54 and the output of the integral adjuster 55 calculated by the adder 56 is input to the upper and lower limit limiter 57. When the addition result is below the upper limit value and above the lower limit value, the upper and lower limit limiter 57 directly outputs the addition result as the adjusted maximum current Imax_adj. On the other hand, when the addition result is greater than the upper limit value, the upper limit value is output as the adjusted maximum current Imax_adj. When the addition result is less than the lower limit value, the lower limit value is output as the adjusted maximum current Imax_adj.

[0120] exist Fig.10 In the configuration example, since the upper limit value is set to the “upper limit value of the maximum current Imax”, the adjusted maximum current Imax_adj does not exceed the “upper limit value of the maximum current Imax”. In addition, since the lower limit value is set to “0”, the adjusted maximum current Imax_adj can be prevented from becoming a negative value.

[0121] Although the configuration example of the maximum current adjustment unit 33a is Fig.10 , but the maximum current Imax supplied to the AC rotating electric machine 18 may be adjusted by other methods.

[0122] Next, Figure 3 The allowable torque calculation unit 34a in FIG. 1 is described below.

[0123] The allowable torque calculation unit 34a first calculates the maximum voltage Vmax based on the following calculation formula using the DC voltage Vdc detected by the voltage detection unit 11 and a preset maximum modulation factor MFmax.

[0124] Vmax=sqrt(3 / 2)×Vdc×(1 / 2)×MFmax

[0125] Then, the allowable torque calculation unit 34 a calculates the maximum interlinkage flux FLmax based on the following calculation formula using the maximum voltage Vmax and the electrical angular velocity ω from the electrical angular velocity calculation unit 14 .

[0126] FLmax=Vmax÷ω

[0127] Furthermore, the permissible torque calculation unit 34a obtains an upper limit value Ctrq_alw_upper and a lower limit value Ctrq_alw_lower of the permissible torque Ctrq_alw based on the maximum interlinkage flux FLmax and the adjusted maximum current Imax_adj from the maximum current adjustment unit 33a.

[0128] Fig.11 and Fig.12 One example of a table is shown as one example for obtaining the upper limit value Ctrq_alw_upper and the lower limit value Ctrq_alw_lower of the allowable torque.

[0129] Fig.11 is a table for obtaining the upper limit value Ctrq_alw_upper of the permissible torque. Fig.12 This is a table for finding the lower limit value Ctrq_alw_lower of the permissible torque. Fig.11 and Fig.12 In FIG. 1 , the horizontal axis represents the maximum linkage flux FLmax, and the vertical axis represents the adjusted maximum current Imax_adj. The allowable torque calculation unit 34a uses, for example, Fig.11 and Fig.12 Use the table in to find the upper limit Ctrq_alw_upper and lower limit Ctrq_alw_lower of the allowable torque.

[0130] in addition, Fig.11 and Fig.12The curve shown is a contour line connecting points with the same allowable torque. The calculation method of the allowable torque is described in detail as follows.

[0131] exist Fig.11 In the table of the upper limit value of the allowable torque shown in FIG. 1 , for example, when the "maximum linkage flux FLmax" and the "adjusted maximum current Imax_adj" are input as shown by the dotted line, the upper limit value Ctrq_alw_upper of the allowable torque is calculated by linear interpolation using the coordinates A, B, C, and D of the four points at the four corners of the grid enclosing the black circle at the intersection. This calculation method is Fig.12 The same applies to the table showing the lower limit value of the allowable torque.

[0132] The upper limit value Ctrq_alw_upper and the lower limit value Ctrq_alw_lower of the allowable torque obtained by the allowable torque calculation unit 34a are input to the torque command adjustment unit 28, and the adjusted torque command value Ctrq_adj is set.

[0133] The torque command adjustment unit 28 sets the value of the adjusted torque command value Ctrq_adj as shown in the following (1) to (3).

[0134] (1) When the torque command value > the upper limit of the allowable torque:

[0135] Ctrq_adj=Ctrq_alw_upper

[0136] (2) When the upper limit of the permissible torque ≥ the torque command value ≥ the lower limit of the permissible torque:

[0137] Ctrq_adj=Ctrq

[0138] (3) When the torque command value is less than the lower limit of the allowable torque:

[0139] Ctrq_adj=Ctrq_alw_lower

[0140] Thus, the adjusted torque command value Ctrq_adj is set, and the adjusted torque command value Ctrq_adj is transmitted to the current command calculation unit 22 .

[0141] As described above, in the first embodiment, the maximum current is adjusted by using the compensated temperature obtained by calculating the compensation value for the temperature of the switching element based on the phase current detection value of the AC rotating electric machine 18 and adding the compensation value to the temperature information of the switching elements 19a to 19c and 20a to 20c instead of directly using the temperature information of the switching elements 19a to 19c and 20a to 20c. On the other hand, in the above-mentioned Patent Document 1, the torque command value of the AC rotating electric machine is adjusted directly using the temperature information of the switching element. In this case, when a large current flows in a short time, the temperature of the switching element may exceed the limit temperature, and the switching element may be damaged. In contrast, in the first embodiment, even when a large current flows in a short time, the temperature of the switching element does not exceed the limit temperature, and the damage of the switching elements 19a to 19c and 20a to 20c can be prevented.

[0142] In addition, by appropriately setting Fig.10 The proportional gain Kpa of the proportional regulator 54 shown can control the temperature of the switching elements 19a to 19c, 20a to 20c so that the compensated temperature of the switching elements 19a to 19c, 20a to 20c does not overshoot the preset limit temperature.

[0143] Next, the respective operations of the case where the overheat protection of the switching elements 19a to 19c, 20a to 20c is performed by applying the first embodiment and the case where the overheat protection of the switching elements is performed by the conventional control method are described. The conventional control method mentioned here refers to the case where the overheat protection operation of the switching elements is performed without adding the compensation value corresponding to the state quantity of the AC rotating electric machine 18 and the temperature of the switching elements in the first embodiment.

[0144] Fig.13 (a)~ Fig.13 (d) is a graph showing a case where the first embodiment is applied to protect the switching elements 19a to 19c and 20a to 20c from overheating.

[0145] Fig.13 (a)~ Fig.13 The horizontal axes of all graphs shown in (d) represent time. Fig.13 The vertical axis of the graph shown in (a) represents the actual switching element temperature. Fig.13 The vertical axis of the graph shown in (b) represents the temperature of the switching element obtained by the temperature detection element. Fig.13 The vertical axis of the graph shown in (c) represents the temperature of the switching element after compensation. Fig.13 The vertical axis of the graph shown in (d) represents the switching element temperature compensation value, Fig.13 The vertical axis of the graph shown in (e) represents the phase current detection value.

[0146] also, Fig.14 (a)~ Fig.14 (c) is a graph showing a case where a switching element is protected from overheating using a conventional control method.

[0147] Fig.14 (a)~ Fig.14 The horizontal axes of all graphs shown in (c) represent time. Fig.14 The vertical axis of the graph shown in (a) represents the actual switching element temperature. Fig.14 The vertical axis of the graph shown in (b) represents the temperature of the switching element obtained by the temperature detection element, and Fig.14 The vertical axis of the graph shown in (c) represents the phase current detection value.

[0148] exist Fig.14 (a)~ Fig.14 In the conventional control method shown in (c), the maximum torque is applied immediately after the start, so that the phase current detection value takes the upper limit value. Fig.14 The temperature of the switching element obtained by the temperature detection element shown in (b) rises and reaches the limit temperature. At this moment, Fig.14 The phase current detection value shown in (c) starts to decrease. That is, by reducing the current that energizes the AC rotating motor 18, the overheat protection action of the switching element begins. However, before the temperature of the switching element obtained by the temperature detection element reaches the limit temperature, Fig.14 The actual switching element temperature shown in (a) overshoots and exceeds the limit temperature. This overshoot can be eliminated by lowering the limit temperature for starting overheat protection, but since the limit temperature is always set low, the overheat protection will excessively limit the current, thus causing the output to drop excessively.

[0149] Next, explain Fig.13 (a)~ Fig.13 The control method of the first embodiment shown in (e) is a case where the switching elements 19a to 19c and 20a to 20c are protected from overheating.

[0150] exist Fig.13 (a)~ Fig.13 In the control method of the first embodiment shown in (e), the maximum torque is applied immediately after the start, so that the phase current detection value becomes the upper limit value. Fig.13 (b) The temperature of the switching element obtained by the temperature detection element rises. In addition, as the phase current detection value rises, Fig.13 The switching element temperature compensation value shown in (d) also increases and takes the upper limit value. This means that in the first embodiment, the compensation value corresponding to the state quantity of the AC rotating electric machine 18 is calculated. Fig.13(b) The temperature of the switching element is obtained by adding the temperature detection element to obtain Fig.13 (c) The compensated temperature of the switching element. The overheat protection of the switching elements 19a to 19c and 20a to 20c is performed according to the compensated temperature of the switching element. Fig.13 (a)~ Fig.13 As shown in (e), when the temperature of the switching element reaches the limit temperature after compensation, overheat protection starts and the phase current detection value decreases. This timing is before the switching element temperature obtained by the temperature detection element reaches the limit temperature.

[0151] As a result, the overheat protection of the switching elements 19a to 19c and 20a to 20c starts early, so that Fig.13 When the actual switching element temperature shown in (a) does not exceed the limit temperature, overheat protection is performed. That is, the control method of the first embodiment can reduce the maximum temperature of the switching elements 19a to 19c and 20a to 20c that exceeds the limit temperature in the conventional control method.

[0152] exist Fig.13 (a)~ Fig.13 In (e), when focusing on the switching element temperature compensation value after the overheat protection action of the switching elements 19a to 19c, 20a to 20c is started, it can be seen that the switching element temperature compensation value converges to "0" as time passes. This means that when the current flowing through the AC rotating motor 18 is lower than the specified phase current detection value Ia, the switching element temperature compensation value becomes "0". That is, in embodiment 1, if the phase current detection value is lower than the specified phase current detection value Ia after the maximum temperature of the switching elements 19a to 19c, 20a to 20c immediately after the instruction of large current flow is dropped, it is not necessary to add the compensation value to the switching element temperature, and excessive output restriction can be avoided.

[0153] Implementation method 2.

[0154] Next, use Fig.15 , a control device for an AC rotating electric machine according to a second embodiment will be described.

[0155] Fig.15 is implemented by Figure 3 The phase current detection value calculation unit 29a is replaced by the phase current command value calculation unit 29b, and reference numeral 17b denotes an overheat protection and torque command unit. In the second embodiment, the differences from the first embodiment are described, and the same parts are given the same reference numerals and their description is omitted.

[0156] The present embodiment is different from the first embodiment in that a phase current command value is used as a state quantity of the AC rotating electric machine 18. Next, the phase current command value calculation unit 29b will be described.

[0157] The phase current command value calculation unit 29b uses Figure 1 The effective value Ciuvw_rms of the phase current commanded to the AC rotating electric machine 18 is calculated by using the d-axis current command value Cid and the q-axis current command value Ciq. The calculated phase current command value Ciuvw_rms is output to the switching element temperature compensation value calculation unit 30b.

[0158] The switching element temperature compensation value calculation unit 30 b calculates a compensation value for the switching element temperature based on the phase current command value Ciuvw_rms, which is a state quantity of the AC rotating electric machine 18 . Fig.16 An example of the change of the switching element temperature compensation value with respect to the phase current command value Ciuvw_rms is shown in . The compensation value is calculated by replacing the phase current detection value iuvw_rms as the state quantity of the AC rotating electric machine 18 in the first embodiment with the phase current command value Ciuvw_rms.

[0159] The predetermined phase current command value Ci_a and the upper limit value Tcu of the switching element temperature compensation value are set based on the same viewpoint as in Embodiment 1. That is, when the compensation for the switching element temperature is not implemented, the maximum phase current command value that does not exceed the limit temperature of the switching elements 19a to 19c, 20a to 20c is set to the predetermined phase current command value Ci_a.

[0160] The upper limit Tcu of the switching element temperature compensation value is set to a temperature drop required for the switching element temperature to drop below the switching element temperature limit temperature when the maximum phase current command value Ci_b that can control the AC rotating electric machine 18 is instructed.

[0161] Implementation method 3.

[0162] Next, use Fig.17 , a control device for an AC rotating electric machine according to a third embodiment will be described.

[0163] Fig.17 is implemented by Figure 3 The phase current detection value calculation unit 29a is replaced with the torque command value (adjusted) 29c, and the reference numeral 17c represents the overheat protection and torque command unit. For the third embodiment, the differences from the first embodiment are described, and the same reference numerals are added to the same parts and the description is omitted.

[0164] This embodiment differs from Embodiment 1 in that an adjusted torque command value is used as the state quantity of the AC rotating motor 18. The adjusted torque command value is used here to use the torque actually instructed to the AC rotating motor 18. Next, the torque command value (after adjustment) 29c will be described.

[0165] The torque command value (adjusted) 29c uses the torque command value Ctrq_adj adjusted by the torque command adjustment unit 28. That is, the adjusted torque command value Ctrq_adj output from the torque command adjustment unit 28 is used as the state quantity of the AC rotating electric machine 18. The adjusted torque command value Ctrq_adj is output to the switching element temperature compensation value calculation unit 30c.

[0166] The switching element temperature compensation value calculation unit 30 c calculates a compensation value for the switching element temperature based on the adjusted torque command value Ctrq_adj, which is a state amount of the AC rotating electric machine 18 . Fig.18 An example of change of the switching element temperature compensation value with respect to the adjusted torque command value Ctrq_adj is shown. The compensation value is calculated by replacing the phase current detection value iuvw_rms, which is the state quantity of the AC rotating electric machine 18 in the first embodiment, with the adjusted torque command value Ctrq_adj.

[0167] The prescribed torque command value Ctrq_a and the upper limit value Tcu of the switching element temperature compensation value are set from the same viewpoint as in Embodiment 1. That is, when the compensation for the switching element temperature is not implemented, the maximum torque command value that does not exceed the limit temperature of the switching elements 19a to 19c, 20a to 20c is set as the prescribed torque command value Ctrq_a. In addition, the upper limit value Tcu of the switching element temperature compensation value is set to the minimum value of the temperature drop required for the switching element temperature to be below the limit temperature of the switching element when the maximum torque command Ctrq_b that can be commanded is applied to the AC rotating motor 18 during control.

[0168] Implementation method 4.

[0169] Next, use Fig.19 , a control device for an AC rotating electric machine according to a fourth embodiment will be described.

[0170] Fig.19 is implemented by Figure 3 The phase current detection value calculation unit 29a is replaced with the torque estimation value calculation unit 29d, and reference numeral 17d indicates an overheat protection and torque command unit. In the fourth embodiment, the differences from the first embodiment are described, and the same parts are given the same reference numerals and the description is omitted.

[0171] This embodiment is different from the first embodiment in that a torque estimation value is used as the state quantity of the AC rotating electric machine 18. Next, the torque estimation value calculation unit 29d will be described.

[0172] The torque estimation value calculation unit 29d estimates the torque output by the AC rotating motor 18. For example, the torque output by the AC rotating motor 18 can be estimated by calculating the mechanical output and dividing the mechanical output by the mechanical angular velocity of the AC rotating motor 18.

[0173] Here, an example of calculating the mechanical output is described. The inverter input power is calculated by multiplying the DC voltage Vdc of the DC power supply 10 by the current flowing from the DC power supply 10 to the inverter 12. Then, the inverter input power is multiplied by the power conversion efficiency of the inverter 12 to calculate the inverter output power. Then, the mechanical output is obtained by subtracting the loss of the AC rotating motor 18 from the inverter output power. At this time, the power conversion efficiency of the inverter 12 and the loss of the AC rotating motor 18 change according to the operating state of the AC rotating motor 18, so the map corresponding to the operating state (hereinafter referred to as MAP) is stored in the control device of the inverter 12. Since the calculation method of the torque estimation value is well known, its detailed description is omitted. Other estimation algorithms can be used to estimate the torque of the AC rotating motor 18. The calculated torque estimation value Etrq is output to the switching element temperature compensation value calculation unit 30d.

[0174] The switching element temperature compensation value calculation unit 30 d calculates a compensation value for the switching element temperature based on the torque estimation value Etrq which is a state quantity of the AC rotating electric machine 18 . Fig. 20 An example of the transition of the switching element temperature compensation value with respect to the torque estimation value Etrq is shown in . The compensation value is calculated by replacing the phase current detection value iuvw_rms, which is the state quantity of the AC rotating electric machine 18 in the first embodiment, with the torque estimation value Etrq.

[0175] The predetermined torque estimation value Etrq_a and the upper limit value Tcu of the switching element temperature compensation value are set based on the same viewpoint as in Embodiment 1. That is, when the compensation for the switching element temperature is not implemented, the maximum torque estimation value that does not exceed the limit temperature of the switching elements 19a to 19c, 20a to 20c is set as the predetermined torque estimation value Etrq_a. In addition, the upper limit value Tcu of the switching element temperature compensation value is set to the minimum value of the temperature drop required for the switching element temperature to be below the limit temperature of the switching element temperature when the maximum torque Etrq_b that the AC rotating motor 18 can output is applied during control.

[0176] Implementation method 5.

[0177] Next, use Fig.21 , a control device for an AC rotating electric machine according to a fifth embodiment will be described.

[0178] Fig.21 In implementation mode 1 Figure 1 In the overheat protection and torque command unit 17, the control amount adjustment unit 33 is replaced by the allowable torque control amount calculation unit 33b, and the reference numeral 17e represents the overheat protection and torque command unit. In the fifth embodiment, the differences from the first embodiment are described, and the same parts are marked with the same reference numerals and the description is omitted.

[0179] The present embodiment is different from the first embodiment in that the allowable torque control amount calculation unit 33b outputs a control amount for limiting the allowable torque, and the allowable torque calculation unit 34b calculates the allowable torque using the control amount.

[0180] Next, the permitted torque control amount calculation unit 33 b will be described.

[0181] The permissible torque control amount calculation unit 33b adjusts the control amount Kc based on the temperature deviation ΔT between the compensated temperature of the switching element and the limit temperature of the switching elements 19a to 19c, 20a to 20c, and outputs the adjusted control amount Kc_adj. Figure 1 The adjusted control amount Cadj in is replaced by the adjusted control amount Kc_adj. The adjusted control amount Kc_adj takes a value between "0" and "1" and is output to the allowable torque calculation unit 34b.

[0182] The torque control amount calculation unit 33b allows the value of the control amount Kc to be adjusted so that the temperature of the switching element after compensation does not exceed the preset limit temperature of the switching elements 19a to 19c, 20a to 20c. In this way, the overshoot of the switching element temperature relative to the preset limit temperature can be suppressed, and the switching elements 19a to 19c, 20a to 20c can be prevented from being damaged due to overheating.

[0183] Fig. 22 FIG. 2 shows a configuration example of the permissible torque control amount calculation unit 33b. Fig. 22 In the structural example, the permissible torque control amount calculation unit 33b includes a proportional regulator 58, an integral regulator 59, and an upper and lower limit limit unit 60. In the permissible torque control amount calculation unit 33b, a temperature deviation ΔT between a preset limit temperature and a temperature after compensation of the switching element is input. The temperature deviation ΔT is a value obtained by subtracting the temperature after compensation of the switching element from the limit temperature. Therefore, when the temperature after compensation of the switching element exceeds the limit temperature, the value of the temperature deviation ΔT becomes a negative value. Therefore, in this case, the higher the temperature after compensation of the switching element, the smaller the value of the temperature deviation ΔT.

[0184] exist Fig. 22 In the configuration example, the proportional gain Kpb of the proportional adjuster 58 is a positive value. The proportional adjuster 58 outputs a value obtained by multiplying the input deviation by the proportional gain Kpb. In addition, the integral adjuster 59 sets the initial value to "1" and integrates the output of the proportional adjuster 58.

[0185] exist Fig. 22 In the structural example, when the temperature of the switching element after compensation is higher than the limit temperature, the output of the proportional adjuster 58 becomes a negative value, and the output of the integral adjuster 59 decreases accordingly. Specifically, when the temperature of the switching element after compensation is higher than the limit temperature, the temperature deviation ΔT becomes a negative value. The proportional adjuster 58 outputs a value obtained by multiplying the temperature deviation ΔT by the proportional gain Kpb. Therefore, when the temperature deviation ΔT is a negative value, the output of the proportional adjuster 58 becomes a negative value. In addition, since the integral adjuster 59 integrates negative values, the output of the integral adjuster 59 gradually decreases from the initial value. On the other hand, when the temperature of the switching element after compensation is below the limit temperature, the output of the proportional adjuster 58 becomes a positive value, and the output of the integral adjuster 59 increases accordingly. Fig. 22 In the configuration example, the output of the proportional adjuster 58 and the output of the integral adjuster 59 are added by the adder 61. The output of the adder 61 becomes the output value of the proportional adjustment and the integral adjustment. As described above, the proportional adjustment and the integral adjustment are performed on the temperature deviation ΔT by the proportional adjuster 58 and the integral adjuster 59.

[0186] exist Fig. 22 In the structural example of, then, the upper and lower limit limiting unit 60 performs upper and lower limit limiting on the output values ​​of proportional adjustment and integral adjustment. In the upper and lower limit limiting unit 60, the upper limit value is set to "1" and the lower limit value is set to "0". The upper and lower limit limiting unit 60 performs upper and lower limit limiting on the output values ​​of proportional adjustment and integral adjustment by using the upper and lower limit values, thereby calculating the adjusted control amount Kc_adj.

[0187] Specifically, the addition result obtained by adding the output of the proportional regulator 58 and the output of the integral regulator 59 by the adder 61 is input to the upper and lower limit limiting unit 60. When the addition result is below the upper limit value and above the lower limit value, the upper and lower limit limiting unit 60 directly outputs the addition result as the adjusted control amount Kc_adj. On the other hand, when the addition result is greater than the upper limit value, the upper limit value is output as the adjusted control amount Kc_adj. When the addition result is less than the lower limit value, the lower limit value is output as the adjusted control amount Kc_adj.

[0188] exist Fig. 22In the configuration example, the upper limit value is set to "1", so the adjusted control amount Kc_adj does not exceed "1". In addition, since the lower limit value is set to "0", it is possible to prevent the adjusted control amount Kc_adj from becoming a negative value.

[0189] Regarding the configuration example of the permissible torque control amount calculation unit 33b, Fig. 22 The structure example of the invention is shown in FIG. 3 , but the control amount Kc for limiting the allowable torque may be adjusted by other methods. That is, the ratio (coefficient) for limiting the allowable torque or the allowable torque reduction amount may be adjusted by other methods. The control amount Kc_adj calculated by the allowable torque control amount calculation unit 33b is output to the allowable torque calculation unit 34b.

[0190] Next, Fig.21 The allowable torque calculation unit 34a in FIG. 1 is described below.

[0191] Fig.23 This is a structural example of the permissible torque calculation unit 34b. First, the speed calculation unit 62 uses the electrical angular velocity ω calculated by the electrical angular velocity calculation unit 14 to calculate the speed N of the AC rotating motor 18. The calculation formula is N[rpm]=60×ω÷(2πp). Here, p is the number of pole pairs of the AC rotating motor 18. The calculated speed N is output to the permissible torque (upper limit) MAP63 and the permissible torque (lower limit) MAP64.

[0192] The allowed torque (upper limit) MAP 63 and the allowed torque (lower limit) MAP 64 respectively output the upper limit and lower limit of the torque value that can be output on the MAP based on the rotation speed N and the DC voltage Vdc. That is, the allowed torque (upper limit) MAP 63 outputs the upper limit value Ctrq_MAP_upper of the torque that can be output on the MAP, and the allowed torque (lower limit) MAP 64 outputs the lower limit value Ctrq_MAP_lower of the torque that can be output on the MAP.

[0193] In the allowable torque (upper limit) MAP 63 and the allowable torque (lower limit) MAP 64, Fig.24 and Fig.25 An example MAP is shown in FIG. For the allowable torque (upper limit) MAP 63, use Fig.24 , and the upper limit value Ctrq_MAP_upper of the torque that can be output on MAP is obtained based on the speed N and the DC voltage Vdc. On the other hand, for the allowable torque (lower limit) MAP64, use Fig.25 , and the lower limit value Ctrq_MAP_lower of the torque that can be output on MAP is calculated based on the speed N and the DC voltage Vdc.

[0194] Ctrq_MAP_upper output from the allowable torque (upper limit) MAP 63 is multiplied by the control amount Kc_adj calculated by the allowable torque control amount calculation unit 33b, and the multiplication result is output to the torque command adjustment unit 28 as the upper limit value Ctrq_alw_upper of the allowable torque.

[0195] On the other hand, Ctrq_MAP_lower output from the allowable torque (lower limit) MAP 64 is multiplied by the control amount Kc_adj calculated by the allowable torque control amount calculation unit 33b, and the multiplication result is output to the torque command adjustment unit 28 as the allowable torque lower limit Ctrq_alw_lower.

[0196] In the fifth embodiment, a control amount Kc_adj whose value is between "0" and "1" is calculated based on the temperature deviation ΔT between the compensated temperature of the switching element and the limit temperature of the switching elements 19a to 19c, 20a to 20c, and the control amount Kc_adj is multiplied by the upper limit value and the lower limit value of the torque that can be output on the MAP, thereby adjusting the upper limit value Ctrq_alw_upper of the allowable torque and the lower limit value Ctrq_alw_lower of the allowable torque. In other words, the allowable torque can be adjusted based on the temperature deviation ΔT between the compensated temperature of the switching element and the limit temperature of the switching elements 19a to 19c, 20a to 20c. After the allowable torque is adjusted, the torque command value is adjusted by the torque command adjustment unit 28 of the subsequent stage, so that the switching element temperature can be controlled to prevent the switching elements 19a to 19c, 20a to 20c from overheating.

[0197] In addition, the allowable torque adjustment unit 32b in the fifth embodiment may be used instead of the allowable torque adjustment unit 32a in the first to fourth embodiments.

[0198] When the overheat protection operation is performed using the control device for the AC rotating electric machine according to Embodiments 1 to 5, the following effects can be obtained.

[0199] In the control device of the present embodiment, a compensation value for the temperature of the switching element is calculated based on the state quantity of the AC rotating electric machine 18 calculated by the AC rotating electric machine state quantity acquisition unit 29, and the control quantity is adjusted by using the sum of the calculated compensation value and the temperature information of the switching elements 19a to 19c, 20a to 20c, thereby calculating the allowable torque. In addition, the switching element temperature can be controlled by adjusting the torque command value based on the calculated allowable torque, and as a result, the switching elements 19a to 19c, 20a to 20c can be prevented from being damaged due to overheating.

[0200] In the control device of the present embodiment, as described above, the switching element temperature compensation value calculation units 30, 30a, 30b, 30c, and 30d calculate a compensation value of a positive value when the AC rotating electric machine state quantity is an appropriate predetermined value or more, and set the compensation value to "0" when the AC rotating electric machine state quantity is a predetermined value or less. As a result, the overheat protection of the switching elements 19a to 19c and 20a to 20c does not need to be started early, and excessive overheat protection operation can be avoided.

[0201] Furthermore, in the control device of the present embodiment, as described above, the switching element temperature compensation value calculation units 30, 30a, 30b, 30c, and 30d calculate the compensation value of a positive value based on the AC rotating motor state quantity being an appropriate prescribed value. Therefore, if the AC rotating motor state quantity becomes lower than the prescribed value after the maximum temperature of the switching elements 19a to 19c, 20a to 20c immediately after the large current is instructed to be energized drops, the compensation value becomes "0". Therefore, there is no need to add the compensation value to the switching element temperature, and excessive output restriction can be avoided.

[0202] In the control device of the present embodiment, as described above, the switching element temperature compensation value calculation units 30, 30a, 30b, 30c, and 30d can set the switching element temperature to within a limit temperature that must not be exceeded during actual use by setting an appropriate upper limit value Tcu of the switching element temperature compensation value, and can prevent excessive current limitation, that is, prevent output reduction.

[0203] In the control devices of embodiments 1 to 4, the maximum current adjustment unit 33a can control the temperature of the switching element by adjusting the maximum current Imax so that the sum of the compensation values ​​obtained by the switching element temperature compensation value calculation units 30, 30a, 30b, 30c and 30d and the temperature information of the switching elements 19a~19c, 20a~20c obtained by the switching element temperature acquisition unit 31 does not exceed the preset limit temperature.

[0204] In the control device of embodiment 5, the torque control amount calculation unit 33b is allowed to control the switching element temperature by adjusting the control amount Kc so that the sum of the compensation value obtained by the switching element temperature compensation value calculation unit 30, 30a, 30b, 30c, 30d and the temperature information of the switching elements 19a~19c, 20a~20c obtained by the switching element temperature acquisition unit 31 does not exceed the preset limit temperature.

[0205] In the control device of this embodiment, since the control amount of the AC rotating electric machine 18 is adjusted by simply adding the compensation value corresponding to the state amount of the AC rotating electric machine 18 to the temperature of the switching element, the maximum temperature of the switching elements 19a to 19c, 20a to 20c can be simply reduced without performing complicated compensation or estimation. In other words, the maximum temperature of the switching element temperature can be simply made within the limit temperature, and the failure of the switching elements 19a to 19c, 20a to 20c can be prevented.

[0206] In addition, each function in the control device of the above-mentioned Embodiments 1 to 5 is realized by a processing circuit. The processing circuit realizing each function may be dedicated hardware or a processor that executes a program stored in a memory.

[0207] When the processing circuit is dedicated hardware, the processing circuit corresponds to, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof. The functions of each part of the inverter control unit 16, the switching element temperature compensation value calculation unit 30, 30a, 30b, 30c, 30d, the control amount adjustment unit 33, the allowable torque calculation unit 34, 34a, 34b, and the torque command adjustment unit 28 can be implemented by a separate processing circuit, or the functions of each part can be implemented by the processing circuit in a unified manner.

[0208] On the other hand, when the processing circuit is a processor, the functions of each part of the inverter control unit 16, the switching element temperature compensation value calculation unit 30, 30a, 30b, 30c, 30d, the control amount adjustment unit 33, the allowable torque calculation unit 34, 34a, 34b and the torque command adjustment unit 28 are realized by software, firmware or a combination of software and firmware. Software and firmware are represented as programs and stored in a memory. The processor reads the program stored in the memory and executes it, thereby realizing the functions of each part. That is, the control device includes a memory for storing a program that, when executed by the processing circuit, executes the inverter control step, the temperature compensation value calculation step, the control amount adjustment step, the allowable torque calculation step and the torque command adjustment step as a result.

[0209] These programs may also be the contents that cause the computer to execute the steps or methods of the above-mentioned parts. Here, the memory is equivalent to, for example, RAM (Random access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory) and other non-volatile or volatile semiconductor memories. In addition, magnetic disks, floppy disks, optical disks, compact disks, mini disks, DVDs, etc. are also equivalent to memory.

[0210] In addition, for the functions of the above-mentioned parts, part of the functions can be implemented by dedicated hardware, and the other parts of the functions can be implemented by software or firmware.

[0211] Therefore, the processing circuit can use hardware, software, firmware or a combination thereof to implement the functions of the above-mentioned parts.

[0212] Although the present application describes various exemplary embodiments and examples, various features, methods, and functions described in one or more embodiments are not limited to application in specific embodiments and may be applied to the embodiments alone or in various combinations.

[0213] Therefore, numerous modifications not shown in the examples are conceivable within the technical scope disclosed in the present application, including, for example, the case where at least one component is modified, added or omitted, and the case where at least one component is extracted and combined with components of other embodiments.

[0214] Description of symbols

[0215] 10 DC power supply, 11 voltage detector, 12 inverter, 13 magnetic pole position detection unit, 14 electrical angular velocity calculation unit, 15a to 15c current sensors, 16 inverter control unit, 17, 17a, 17b, 17c, 17d, 17e overheat protection and torque command unit, 18 AC rotating motor, 19a to 19c, 20a to 20c switching elements, 21 three-phase to two-phase current conversion unit, 22 current command calculation unit, 23d-axis current controller, 24q-axis current controller, 25 two-phase to three-phase voltage conversion unit, 26 PWM circuit, 27 gate driver, 28 torque command adjustment unit, 29 AC rotating motor state quantity acquisition unit, 29a phase current detection value calculation unit, 29b phase current command value calculation unit, 29c torque command value (after adjustment), 29d torque estimation value Calculation unit, 30, 30a, 30b, 30c, 30d switching element temperature compensation value calculation unit, 31 switching element temperature acquisition unit, 32, 32a, 32b allowable torque adjustment unit, 33 control amount adjustment unit, 33a maximum current adjustment unit, 33b allowable torque control amount calculation unit, 34, 34a, 34b allowable torque calculation unit, 50 temperature detection element, 51 substrate, 52 effective area, 53 near the center, 54, 58 proportional regulator, 55, 59 integral regulator, 56, 61 adder, 57, 60 upper and lower limit limit units, 62 speed calculation unit, 63 allowable torque (upper limit) MAP, 64 allowable torque (lower limit) MAP, P high voltage side node, N low voltage side node, D1~D3, D4~D6 rectifying elements, Uac, Vac, Wac connection node.

Claims

1. A control device for an AC rotating electrical machine, characterized in that: include: a switching element temperature acquisition unit connected to a power conversion circuit for driving an AC rotating electric machine and acquiring temperature information of a switching element of the power conversion circuit; an AC rotating electric machine state quantity acquisition unit, the AC rotating electric machine state quantity acquisition unit acquiring a state quantity of the AC rotating electric machine; a switching element temperature compensation value calculation unit, the switching element temperature compensation value calculation unit calculating a compensation value for the switching element temperature based on a state quantity of the AC rotating electric machine; as well as An allowable torque adjustment unit, which adjusts the torque that the AC rotating motor can output, includes: a control amount adjustment unit, which adjusts the control amount of the AC rotating motor based on the temperature deviation between the sum of the temperature information of the switching element acquired by the switching element temperature acquisition unit and the compensation value calculated by the switching element temperature compensation value calculation unit, that is, the compensated temperature of the switching element and the preset limit temperature of the switching element, so that the compensated temperature of the switching element does not exceed the limit temperature; and an allowable torque calculation unit, which calculates the torque that the AC rotating motor can output based on the control amount adjusted by the control amount adjustment unit.

2. The control device for an AC rotating electrical machine according to claim 1, characterized in that: The state amount is any one of a detected amount of current supplied to the AC rotating motor, a command amount of current supplied to the AC rotating motor, an estimated amount of torque output by the AC rotating motor, and a command amount of torque output by the AC rotating motor.

3. The control device for an AC rotating electrical machine according to claim 1, wherein: The state quantity is determined using two or more of a detected amount of current supplied to the AC rotating motor, a commanded amount of current supplied to the AC rotating motor, an estimated amount of torque output by the AC rotating motor, and a commanded amount of torque output by the AC rotating motor.

4. The control device for an AC rotating electrical machine according to any one of claims 1 to 3, characterized in that: The temperature information of the switching element is a detected amount of the temperature of the switching element.

5. The control device for an AC rotating electrical machine according to any one of claims 1 to 3, characterized in that: The temperature information of the switching element is an estimated measure of the temperature of the switching element.

6. The control device for an AC rotating electrical machine according to any one of claims 1 to 3, characterized in that: The control amount adjustment unit adjusts a maximum value of a current supplied to the AC rotating electric machine.

7. The control device for an AC rotating electrical machine according to any one of claims 1 to 3, characterized in that: When the state quantity of the AC rotating motor is less than a specified value, the switching element temperature compensation value calculation unit outputs zero, and when the state quantity of the AC rotating motor is greater than the specified value, the switching element temperature compensation value calculation unit uses the upper limit compensation value as the upper limit and outputs a positive value according to the state quantity of the AC rotating motor.

8. The control device for an AC rotating electrical machine according to claim 7, characterized in that: The predetermined value is set to a maximum value such that the temperature information of the switching element does not exceed the limit temperature of the switching element even when the compensation value calculated by the switching element temperature compensation value calculation unit is not added to the temperature information of the switching element.

9. The control device for an AC rotating electrical machine according to claim 7, characterized in that: The upper limit compensation value is set to a minimum value of a temperature drop amount when the temperature information of the switching element is equal to or lower than a limit temperature of the switching element.

10. The control device for an AC rotating electrical machine according to claim 8, wherein: The upper limit compensation value is set to a minimum value of a temperature drop amount when the temperature information of the switching element is equal to or lower than a limit temperature of the switching element.

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