CN113507248A

CN113507248A - Control device for AC rotating machine

Info

Publication number: CN113507248A
Application number: CN202110279495.6A
Authority: CN
Inventors: 四元信一朗; 岸和田优; 冈部健; 原田信吾; 田村卓哉
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2020-03-23
Filing date: 2021-03-16
Publication date: 2021-10-15
Also published as: JP2021151140A; JP6873293B1

Abstract

The invention provides a control device for an alternating-current rotating electric machine, which can restrain the temperature rise of a switching element caused by the current conduction of a large current and can perform overheat protection below a limit temperature. The control device includes: a switching element temperature acquisition unit (31) that acquires the temperature of the switching elements (19 a-19 c, 20 a-20 c); a switching element temperature compensation value calculation unit (30) that calculates a compensation value based on the state quantity of the AC rotating machine (18) acquired by the AC rotating machine state quantity acquisition unit (29); and allowable torque adjusting units (32, 32a, 32b) for adjusting the allowable torque of the AC rotating machine (18) so that the sum of the switching element temperature and the compensation value does not exceed the limit temperature of the switching elements (19a to 19c, 20a to 20 c).

Description

Control device for AC rotating machine

Technical Field

The present application relates to a control device for an ac rotating machine.

Background

Generally, an electric vehicle such as an electric vehicle or a hybrid vehicle is equipped with an ac rotating electric machine for driving the vehicle or for recovering deceleration energy of the vehicle. The ac rotating machine is connected to a power conversion circuit having a switching element, and converts dc power of a dc power supply (battery) into ac power or converts ac power generated by the ac rotating machine into dc power. The switching element referred to herein is a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), an IGBT (Insulated Gate Bipolar Transistor), or the like.

In general, the switching element is provided with a temperature that must never be exceeded, the limit temperature, and once this temperature is exceeded, damage is possible. Therefore, a control of the overheat protection is proposed so that the switching element does not exceed the limit temperature which the switching element has.

For example, according to a conventional power conversion device disclosed in patent document 1, there is proposed a method of correcting a torque command value of an ac rotating machine when a temperature of a power semiconductor is equal to or higher than a set temperature so that the temperature of the power semiconductor coincides with the set temperature.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 6107936

Disclosure of Invention

Technical problem to be solved by the invention

In general, a permanent magnet synchronous motor is widely used as an ac rotating machine driven by an inverter. The torque of the permanent magnet synchronous motor is determined by the magnetic force of the rotor and the current flowing through the stator coil, and the magnetic force of the rotor is determined by the type or structure of the magnet, so that the torque of the ac rotating machine is controlled by the current flowing through the stator coil. That is, the larger the current that energizes the stator coil, the larger the torque that can be obtained by the permanent magnet synchronous motor. In addition, when the rotational speed of the ac rotating machine is constant, the permanent magnet synchronous motor can obtain a large output.

However, the current that can be passed through an ac rotating electrical machine such as a permanent magnet synchronous motor is generally determined by the specifications of switching elements used in a power conversion circuit or cooling performance for cooling the switching elements. This is because, as described above, the switching element has a limit temperature, and if this temperature is exceeded, there is a possibility of damage.

The temperature rise of the switching element due to energization can be determined by the product of the loss of the switching element due to 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 to be supplied, and the thermal resistance from the switching element to the cooling body has a response with a first order delay. Therefore, even if the same current is applied, if the applied time is different, the temperature rise of the switching element is different. That is, even if the temperature rise of the switching element is the same, if the time is shorter, the larger the current that can be applied, the larger the output that can be obtained.

In some usage modes of an ac rotating electric machine used in an electric vehicle such as an electric vehicle or a hybrid vehicle, a large current may be output in a short time. This is the case when the engine is started or when the regenerative energy is recovered during deceleration. In this case, a large current needs to be supplied to the ac rotating electric machine, and the temperature of the switching element may exceed the limit temperature immediately after the torque command is issued.

In patent document 1, it is proposed that when the switching element temperature becomes equal to or higher than the set temperature, the control is performed so that the switching element temperature matches the set temperature, but when a large torque is instantaneously applied, the temperature of the switching element may overshoot and exceed the limit temperature. Further, when the temperature of the switching element is assumed to overshoot and exceed the limit temperature in advance and the set temperature of the switching element is set to be low, the current to be supplied to the ac rotating electric machine is reduced, and the output is lowered.

The present application discloses a technique for solving the above-described problems, and an object thereof is to provide a control device for an ac rotating electrical machine, which can suppress a temperature rise of a switching element due to a large current application and can perform overheat protection at a limit temperature or lower.

Means for solving the problems

The control device for an ac rotating machine disclosed in the present application is characterized by comprising: a switching element temperature acquisition section that acquires temperature information of a switching element connected to a power conversion circuit for driving an alternating-current rotary electric machine; an ac rotating machine state quantity acquisition unit that acquires a state quantity of the ac rotating machine; a switching element temperature compensation value calculation unit that calculates a compensation value for a switching element temperature based on a state quantity of the ac rotating electrical machine; and an allowable torque adjustment unit that adjusts the torque that can be output by the ac rotating electrical machine 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.

Effects of the invention

According to the control device for an ac rotating machine disclosed in the present application, it is possible to provide a control device for an ac rotating machine that can suppress a temperature rise of a switching element due to large-current energization and can perform overheat protection at a limit temperature or lower.

Drawings

Fig. 1 is a configuration diagram of a control device for an ac rotating machine according to embodiment 1.

Fig. 2 is a flowchart illustrating an operation of the control device for the ac rotating electric machine according to embodiment 1.

Fig. 3 is a diagram showing different configurations of an overheat protection and a torque command unit in the control device for an ac rotating electric machine according to embodiment 1.

Fig. 4 is a diagram showing a first example of a compensation value calculation unit for a switching element temperature compensation value in the control device for an ac rotating electrical machine according to embodiment 1.

Fig. 5 is a diagram showing a second example of a variation of the compensation value in the switching element temperature compensation value calculation unit of the control device for an ac rotating electrical machine according to embodiment 1.

Fig. 6 is a diagram illustrating a method for determining a predetermined value in a switching element temperature compensation value calculation unit of the control device for an ac rotating electrical machine according to embodiment 1.

Fig. 7 is a diagram of example 1 in which the control device of the ac rotating electric machine according to embodiment 1 detects the temperature of the switching element.

Fig. 8 is a diagram of example 2 in which the control device of the ac rotating electric machine according to embodiment 1 detects the temperature of the switching element.

Fig. 9 is an example of the evolution of the relationship between the switching element temperature obtained by the temperature detection element and the actual switching element temperature in the control device for the ac rotating electric machine according to embodiment 1.

Fig. 10 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 embodiment 1.

Fig. 11 is a diagram illustrating a method of calculating the allowable torque upper limit value in the allowable torque calculation unit of the control device for an ac rotating electric machine according to embodiment 1.

Fig. 12 is a diagram illustrating a method of calculating the allowable torque lower limit value in the allowable torque calculation unit of the control device for an ac rotating electric machine according to embodiment 1.

Fig. 13 is a diagram showing an operation performed when the control device for an ac rotating electric machine according to embodiment 1 controls the temperature of the switching element.

Fig. 14 is a diagram showing an operation performed when a conventional control device for an ac rotating electric machine performs temperature control of a switching element.

Fig. 15 is a diagram showing a further different configuration of an overheat protection and torque command unit in the control device for an ac rotating electric machine according to embodiment 1.

Fig. 16 is a diagram showing an example of the change in the compensation value in the switching element temperature compensation value calculation unit of the control device for an ac rotating electrical machine according to embodiment 2.

Fig. 17 is a diagram showing a further different configuration of an overheat protection and torque command unit in the control device for an ac rotating electric machine according to embodiment 1.

Fig. 18 is a diagram showing an example of the change in the compensation value in the switching element temperature compensation value calculation unit of the control device for an ac rotating electrical machine according to embodiment 3.

Fig. 19 is a diagram showing a further different configuration of an overheat protection and torque command unit in the control device for an ac rotating electric machine according to embodiment 1.

Fig. 20 is a diagram showing an example of the change in the compensation value in the switching element temperature compensation value calculation unit of the control device for an ac rotating electrical machine according to embodiment 4.

Fig. 21 is a diagram showing different configurations of an overheat protection and a torque command unit in the control device for an ac rotating electric machine according to embodiment 1.

Fig. 22 is a configuration diagram showing an example of an allowable torque control amount calculation unit of the control device for an ac rotating electric machine according to embodiment 5.

Fig. 23 is a configuration diagram showing an example of an allowable torque calculation unit of the control device for the ac rotating electric machine according to embodiment 5.

Fig. 24 is a diagram illustrating a method of calculating the allowable torque upper limit value in the allowable torque calculation unit of the control device for an ac rotating electric machine according to embodiment 5.

Fig. 25 is a diagram illustrating a method of calculating the allowable torque lower limit value in the allowable torque calculation unit of the control device for an ac rotating electric machine according to embodiment 5.

Detailed Description

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

Embodiment 1.

Fig. 1 is a configuration diagram of a control device for an ac rotating machine according to embodiment 1. As shown in fig. 1, the control device for the ac rotating electrical 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 to 15c, an inverter control unit 16, and an overheat protection and torque command unit 17, and controls an ac rotating electrical machine 18.

The control device for an ac rotating machine according to embodiment 1 is configured as described above, and the configurations of the respective portions thereof will be described below.

The dc power supply 10 is a chargeable/dischargeable power supply, and exchanges power 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 to boost the DC voltage supplied from the DC power supply 10 by DC/DC conversion. In addition, a filter capacitor for filtering the direct voltage may be connected between the high voltage side node P and the low voltage side node N.

The voltage detection unit 11 detects the dc voltage Vdc of the dc power supply 10. Specifically, the voltage detection section 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 direct-current voltage Vdc.

As shown in fig. 1, 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 a DC voltage from the DC power supply 10 into an AC voltage by DC/AC conversion by 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. Then, the obtained ac voltage is applied to the ac rotating electrical machine 18.

In the inverter 12, the rectifier devices D1 to D3 and D4 to D6 are connected in antiparallel to the upper-arm-side switching devices 19a to 19c and the lower-arm-side switching devices 20a to 20c, respectively. When the switching elements 19a to 19c and 20a to 20c are MOSFETs, the rectifying elements are present inside the MOSFETs themselves. On the other hand, IGBTs may be used as the switching elements 19a to 19c, 20a to 20c, and as a connection method of the switching elements and the rectifying elements in this case, for example, a cathode electrode of the rectifying element is connected to a collector electrode of the switching element, and an anode electrode of the rectifying element is connected to an emitter electrode of the switching element.

The ac rotating electrical machine 18 is applied with the ac voltage output from the inverter 12, and controls the driving force and the braking force of the vehicle. The ac rotating electrical machine 18 is constituted by, for example, a permanent magnet synchronous motor. In the present embodiment, an ac rotating electrical machine having a three-phase armature winding is described as an example of the ac rotating electrical machine 18. However, the number of phases of the ac rotating electrical machine 18 is not limited to three phases, and may be any number of phases. That is, the control device of the present embodiment is applied to an ac rotating electrical machine having a multi-phase armature winding.

The magnetic pole position detection unit 13 detects the magnetic pole position of the ac rotating electrical machine 18. The magnetic pole position detection unit 13 includes a hall element, a resolver, or an encoder. The magnetic pole position detection unit 13 detects a rotation angle of a magnetic pole of a rotor of the ac rotating electric machine 18 with respect to a reference rotation position, and outputs a signal indicating a detected value of the detected rotation angle as a magnetic pole position θ. Here, the magnetic pole position θ represents a rotation angle of the q axis. The reference rotational position of the rotor is set to an arbitrary position as appropriate.

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 electrical machine 18 by a hall element, an encoder, or the like.

The current sensors 15a to 15c detect the amounts of currents 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-two-phase current conversion unit 21. In fig. 1, 3 current sensors 15a to 15c are provided to detect the current amounts of the U-phase, V-phase, and W-phase, respectively, but the present invention is not limited thereto, and the number of current sensors may be 2. In this case, the current amount is detected only in two phases, and the current amount of one phase is calculated from the detected current amounts of the two phases.

The inverter control unit 16 controls the switching operations of the upper arm-side switching elements 19a to 19c and the lower arm-side switching elements 20a to 20c 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 electrical machine 18 and controlling the amount of current flowing through the ac rotating electrical machine 18. The configuration of the inverter control unit 16 will be described below.

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/three-phase voltage conversion unit 25, a PWM (pulse width modulation) circuit 26, a gate driver 27, and a three-phase/two-phase current conversion unit 21. The inverter control unit 16 controls the inverter 12 by dq vector control, thereby controlling the rotation of the ac rotating machine 18. Hereinafter, each part constituting the inverter control unit 16 will be described.

The adjusted torque command value Ctrq _ adj for commanding the torque generated in the ac rotating electrical machine 18 is input from the torque command adjusting section 28 of the overheat protection and torque command section 17 to the current command computing section 22. The current command calculation unit 22 calculates a d-axis current command value Cid and a 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.

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

The d-axis current controller 23 calculates a d-axis voltage command value Cvd of a direct current so that a deviation between the d-axis current command value Cid from the current command operation 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 d-axis voltage command value Cvd of the direct current to the two-phase to three-phase voltage conversion unit 25.

The q-axis current controller 24 calculates a q-axis voltage command value Cvq of a direct current so that a deviation between the q-axis current command value Ciq from the current command operation 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 q-axis voltage command value Cvq of the direct current to the two-phase to three-phase voltage conversion unit 25.

The two-phase/three-phase voltage conversion unit 25 converts the two-phase direct current d-axis voltage command value Cvd and the q-axis voltage command value Cvq into three-phase alternating current voltage command values Cvu, Cvv, and Cvw based on the magnetic pole position θ from the magnetic pole position detection unit 13, and outputs them to the PWM circuit 26.

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

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

The overheat protection and torque command unit 17 includes an ac rotating electrical 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 and torque command adjustment of the switching elements 19a to 19c, and 20a to 20 c. The allowable torque adjusting unit 32 is composed of a control amount adjusting unit 33 and an allowable torque calculating unit 34. The following describes the respective components constituting the overheat protection and torque command unit 17.

The ac rotating machine state quantity acquisition unit 29 acquires the state quantity of the ac rotating machine 18 to be controlled. The specific state quantity may be any one or two or more of a detected quantity of current flowing through the ac rotating electric machine 18, a command quantity of current flowing through the ac rotating electric machine 18, an estimated quantity of torque output by the ac rotating electric machine 18, and a command quantity of torque output by the ac rotating electric machine 18. The obtained state quantity of the ac rotating electrical machine 18 is output to the switching element temperature compensation value calculation unit 30.

The switching element temperature compensation value calculation unit 30 calculates a compensation value that is zero or a positive value based on the state quantity from the ac rotating electrical machine state quantity acquisition unit 29. And outputting the calculated compensation value as a temperature compensation value of the switching element. The specific operation of the switching element temperature compensation value calculation unit 30 will be described later.

The switching element temperature acquisition unit 31 acquires the temperatures of the switching elements 19a to 19c, 20a to 20c of the inverter 12. As a method of acquiring the temperatures of the switching elements 19a to 19c, 20a to 20c, for example, temperature detection elements whose output voltages change in proportion to the temperatures are provided on the same substrate as the switching elements 19a to 19c, 20a to 20c, and the temperatures of the switching elements 19a to 19c, 20a to 20c are acquired by measuring the output voltages of the temperature detection elements and performing temperature conversion on the measured output voltages. Alternatively, the temperature increase values of the switching elements 19a to 19c, 20a to 20c may be obtained by multiplying the losses of the switching elements 19a to 19c, 20a to 20c generated in each operation mode by the thermal resistances between the switching elements 19a to 19c, 20a to 20c and the cooling body, and the estimated values of the switching element temperatures may be obtained from the sum of the temperature increase values and the cooling body temperature. Since an algorithm for estimating the temperatures of the switching elements 19a to 19c, 20a to 20c is well known, detailed description thereof is omitted here. Other estimation algorithms may be used to estimate the temperatures of the switching elements 19a to 19c, 20a to 20 c.

The control amount adjusting unit 33 adjusts the control amount of the ac rotating electric machine 18 and outputs the adjusted control amount Cadj. The control amount adjusting unit 33 limits the control amount of the ac rotating electrical machine 18 so that the sum of the switching element temperature and the switching element temperature compensation value does not exceed a preset limit temperature of the switching elements 19a to 19c, 20a to 20 c. This suppresses overshoot of the switching element temperature of the inverter 12 with respect to the preset limit temperature, and prevents the switching elements 19a to 19c and 20a to 20c from being damaged by overheating. Here, the control amount of the ac rotating electrical machine 18 is a control amount for limiting the maximum value of the current flowing through the ac rotating electrical machine 18 or the allowable torque. The specific configuration and operation of the control amount adjusting unit 33 will be described later.

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 method of calculating the allowable torque Ctrq _ alw in the allowable torque calculation unit 34 will be described later.

The torque command adjustment unit 28 adjusts the torque command value Ctrq of the ac rotating electrical 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 operation unit 22.

Next, the flow of operation in the overheat protection and torque command unit 17 shown in fig. 1 will be described with reference to the flowchart of fig. 2.

First, in step S100, the control of the control device shown in fig. 1 is started.

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

In step S102, the switching element temperature acquisition unit 31 acquires the temperatures of the switching elements 19a to 19c and 20a to 20 c. Then, the process proceeds to step S103.

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

In step S104, a compensation value for the switching element temperature is calculated based on the state quantity output from the ac rotating electrical machine state quantity acquisition unit 29. Then, the process proceeds to step S105.

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, and the post-switching-element-compensation temperature is obtained. Then, the process proceeds to step S106.

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

In step S107, the control amount adjustment unit 33 adjusts the control amount based on the temperature deviation Δ T calculated in step S106 so that the post-switching element compensation 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.

In step S108, the upper limit value Ctrq _ alw _ upper of the allowable torque and the lower limit value Ctrq _ alw _ lower of the allowable torque are calculated based on the control amount Cadj of step S107. Then, the process proceeds to step S109.

In step S109, a torque command value Ctrq that commands the ac rotating electric machine 18 is acquired. Then, the process proceeds to step S110.

In step S110, the upper limit value Ctrq _ alw _ upper of the allowable torque calculated in step S108 is compared with the torque command value Ctrq acquired in step S109. When the torque command value Ctrq > upper limit value Ctrq _ alw _ upper of allowable torque is established, the process goes to yes, and step S112 is executed, and when the torque command value Ctrq > upper limit value Ctrq _ alw _ upper of allowable torque is not established, the process goes to no, and step S111 is executed.

In step S111, the lower limit value Ctrq _ alw _ lower of the allowable torque calculated in step S108 is compared with the torque command value Ctrq acquired in step S109. When the torque command value Ctrq < the lower limit value Ctrq _ alw _ lower of the allowable torque is established, the process proceeds to yes, and step S113 is executed, and when the torque command value Ctrq < the lower limit value Ctrq _ alw _ lower of the allowable torque is not established, the process proceeds to no, and step S114 is executed.

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.

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.

In step S114, the adjusted torque command value Ctrq _ adj is set to the torque command value Ctrq acquired in step S109. Then, the process proceeds to step S115.

In step S115, the series of operations ends.

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 in this order.

Next, the overheat protection and torque command unit 17 shown in fig. 1 will be described in detail based on fig. 3, with the state quantity of the ac rotating electrical machine 18 as the phase current detection value and the control quantity as the maximum current value.

In fig. 3, the overheat protection and torque command section 17 shown in fig. 1 is configured to have the alternating-current rotating electric machine state quantity acquisition section 29 replaced with a phase current detection value calculation section 29a, and the control quantity adjustment section 33 replaced with a maximum current adjustment section 33a as an overheat protection and torque command section 17 a. However, the alternative shown in fig. 3 is an example, and as described above, the state quantity of the alternating-current rotary electric machine 18 may be a phase current command value, a torque presumption value, or a torque command value, and the control quantity may be a control quantity for limiting the allowable torque. Here, the case of fig. 3 is explained as an example. In fig. 3, reference numeral 30a denotes a switching element temperature compensation value calculation unit, reference numeral 32a denotes an allowable torque adjustment unit, and reference numeral 34a denotes an allowable torque calculation unit. Note that the same operational parts as those in the operation of fig. 1 are not described.

The phase current detection value calculation unit 29a calculates an effective value iuvw _ rms of a 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 to the switching element temperature compensation value calculation unit 30a as a phase current detection value.

The switching element temperature compensation value calculation unit 30a calculates a compensation value that is zero or a positive value based on the phase current detection value iuvw _ rms from the phase current detection value calculation unit 29 a. The calculated compensation value is outputted as a switching element temperature compensation value.

Here, a method of calculating the switching element temperature compensation value from the phase current detection value iuvw _ rms will be described.

Fig. 4 shows a first variation of the switching element temperature compensation value for the phase current detection value iuvw _ rms.

In fig. 4, the horizontal axis represents the phase current detection value iuvw _ rms, and the vertical axis represents the switching element temperature compensation value. In fig. 4, when the phase current detection value iuvw _ rms is equal to or less than a predetermined value, that is, equal to or less than the predetermined phase current detection value Ia, the switching element temperature compensation value is calculated as "0". On the other hand, when the phase current detection value iuvw _ rms is larger than the predetermined phase current detection value Ia, a compensation value that is a positive 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 an upper limit.

As shown in the second modified example of fig. 5, the compensation value for the phase current detection value iuvw _ rms may be calculated in a curve shape for the switching element temperature compensation value. The phase current detection value Ib shown in fig. 4 and 5 is set to a maximum phase current effective value that can flow through the ac rotating electric machine 18 during control.

Next, the predetermined phase current detection value Ia and the upper limit value Tcu of the switching element temperature compensation value in fig. 4 and 5 will be described based on fig. 6.

Fig. 6 is a graph showing a relationship of the switching element temperature with respect to the phase current detection value. Normally, when the current flowing through the ac rotating electric machine 18 increases, the switching element temperature increases.

Tch in fig. 6 is a limit temperature that the switching elements 19a to 19c, 20a to 20c cannot exceed in terms of specification. The predetermined phase current detection value Ia is a 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 predetermined phase current detection value Ia is the maximum phase current detection value that does 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 30 a.

Tmax in fig. 6 indicates the temperature reached by the switching elements 19a to 19c, 20a to 20c when the ac rotating electric machine 18 is energized with the maximum phase current effective value Ib to which current can be applied. This temperature Tmax is generally higher than the limit temperature Tch of the switching elements 19a to 19c, 20a to 20c, and is expressed as Tmax + α. α when expressed in this manner is set to the upper limit value Tcu of the switching element temperature compensation value. That is, the minimum value α of the temperature decrease amount required for the switching element temperature when the ac rotating electric machine 18 is energized at the maximum effective phase current value Ib at which the ac rotating electric machine can be energized to be equal to or lower than the limit temperature Tch of the switching elements 19a to 19c, 20a to 20c is set.

The following should be noted with respect to the overheat protection of the switching elements 19a to 19c and 20a to 20 c.

Since there is not a small deviation between the switching element temperature obtained from the temperature detection element and the actual switching element temperature, the actual switching element temperature may be higher than the temperature information obtained by the temperature detection element. In this case, since the switching element temperature obtained by the temperature detection element is not to be protected, but the actual switching element temperature having a high temperature is to be protected, it is necessary to perform overheat protection so that the actual switching element temperature becomes equal to or lower than the limit temperature.

Next, 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 with reference to fig. 7 and 8.

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, it is conceivable to provide the temperature detection element 50 as shown in fig. 7 and 8.

Fig. 7 shows a case where the temperature detection element 50 is located at a corner portion on the substrate 51 on which the switching elements 19a to 19c, 20a to 20c are arranged. On the other hand, fig. 8 shows a case where the temperature detection element 50 is located at the center on the substrate 51 on which the switching elements 19a to 19c, 20a to 20c are arranged. When comparing the effective regions 52 on which the switching elements 19a to 19c and 20a to 20c can be mounted in fig. 7 and 8, the effective regions 52 on which the switching elements 19a to 19c and 20a to 20c can be mounted can be set to be large so that the temperature detection element 50 is located at the corner portions of the substrate 51 on which the switching elements 19a to 19c and 20a to 20c are provided as shown in fig. 7.

The reason for this is that the arrangement of fig. 7 does not require much area for wiring compared to the arrangement of fig. 8. When the region in which the switching elements 19a to 19c and 20a to 20c can be mounted is large, that is, in the arrangement of fig. 7, a larger current can be applied than in the case of fig. 8. However, on the substrate 51 on which the switching elements 19a to 19c, 20a to 20c are arranged, a portion where the temperature is most likely to rise is the vicinity 53 of the center of the substrate 51 on which the switching elements 19a to 19c, 20a to 20c are arranged. Therefore, when the configuration of the temperature detection element 50 as shown in fig. 7 is adopted, a difference is generated between the highest temperature of the switching elements 19a to 19c, 20a to 20c and the temperature detected by the temperature detection element 50.

Fig. 9 is a graph showing an example of a time transition between an actual switching element temperature a and a switching element temperature B obtained by the temperature detection element 50 in the arrangement of the temperature detection element 50 shown in fig. 7, and shows temperatures at which a certain loss occurs in each of the switching elements 19a to 19c and 20a to 20 c.

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 because there are thermal resistance and thermal capacity between the central 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 with respect to the temperature rise of the actual switching element temperature, and has a time-varying temperature difference.

Next, the maximum current adjustment unit 33a will be described with reference to fig. 3.

The maximum current adjustment unit 33a adjusts the maximum current Imax based on the temperature deviation Δ T between the temperature compensated by the switching elements and the limit temperatures of the switching elements 19a to 19c and 20a to 20c, and outputs the adjusted maximum current Imax _ adj. That is, this corresponds to the case where the adjusted control amount Cadj in fig. 1 is replaced with the adjusted maximum current Imax _ adj. The adjusted maximum current Imax _ adj represents a maximum current value allowed at the present time with respect to the phase current absolute value represented by the following equation.

The maximum current adjusting unit 33a adjusts the value of the maximum current Imax so that the temperature after the switching element compensation does not exceed the preset limit temperature of the switching elements 19a to 19c, 20a to 20 c. This can suppress the switching element temperature of the inverter 12 from overshooting the preset limit temperature, and prevent the switching elements 19a to 19c, 20a to 20c from being damaged by overheating.

Fig. 10 shows a configuration example of the maximum current adjustment unit 33 a. In the configuration example of fig. 10, 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 limiting unit 57. The temperature deviation Δ T between the limit temperature set in advance and the temperature compensated by the switching element is input to the maximum current adjustment unit 33 a. The temperature deviation Δ T is a value obtained by subtracting the temperature compensated by the switching element from the limit temperature. Therefore, when the temperature after the switching element compensation exceeds the limit temperature, the value of the temperature deviation Δ T becomes a negative value. Therefore, in this case, the higher the temperature after the switching element compensation, the smaller the value of the temperature deviation Δ T.

In the configuration example of fig. 10, 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 a proportional gain Kpa.

In the configuration example of fig. 10, the initial value of the integral adjuster 55 is set as the "upper limit value of the maximum current Imax", and the output of the proportional adjuster 54 is integrated. The "upper limit value of the maximum current Imax" is a value obtained by calculating the "absolute value of the phase current" expressed by the above equation using the designed maximum d-axis current and the maximum q-axis current. That is, under any conditions, a current larger than the "absolute value of phase current" of the "upper limit value of the maximum current Imax" is not intentionally caused to flow. On the other hand, the maximum current Imax is a variable amount, and is adjusted between "0" and "an upper limit value of the maximum current Imax".

In the configuration example of fig. 10, when the temperature becomes higher than the limit temperature after the switching element compensation, the output of the proportional regulator 54 becomes a negative value, and the output of the integral regulator 55 decreases accordingly. Specifically, when the temperature after the compensation of the switching element is higher than the limit temperature, the temperature deviation Δ T becomes a negative value. The proportional regulator 54 outputs a value obtained by multiplying the deviation by a proportional gain Kpa. Therefore, when the temperature deviation Δ T is a negative value, the output of the proportional regulator 54 becomes a negative value. Further, since the integration adjuster 55 integrates a negative value, the output of the integration adjuster 55 gradually decreases from the initial value. On the other hand, when the temperature after the switching element compensation is equal to or lower than the limit temperature, the output of the proportional regulator 54 becomes a positive value, and the output of the integral regulator 55 increases accordingly. In the configuration example of fig. 10, the output of the proportional regulator 54 and the output of the integral regulator 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 temperature deviation Δ T is subjected to proportional adjustment and integral adjustment by the proportional adjuster 54 and the integral adjuster 55.

In the configuration example of fig. 10, next, the upper and lower limit limiting section 57 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 section 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.

Specifically, the addition result of the output of the proportional regulator 54 and the output of the integral regulator 55 calculated by the adder 56 is input to the upper and lower limit limiting unit 57. When the addition result is equal to or smaller than the upper limit value and equal to or larger than the lower limit value, the upper and lower limit limiting unit 57 directly outputs the addition result as the adjusted maximum current Imax _ adj. On the other hand, when the addition result is larger than the upper limit value, the upper limit value is output as the adjusted maximum current Imax _ adj. When the addition result is smaller than the lower limit value, the lower limit value is output as the adjusted maximum current Imax _ adj.

In the configuration example of fig. 10, 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". Further, since the lower limit value is set to "0", the adjusted maximum current Imax _ adj can be prevented from becoming a negative value.

Although a configuration example is shown in fig. 10 with respect to a configuration example of the maximum current adjustment unit 33a, the maximum current Imax that energizes the ac rotating electrical machine 18 may be adjusted by another method.

Next, the allowable torque calculation unit 34a in fig. 3 will be described.

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 the preset maximum modulation rate MFmax.

Vmax＝sqrt(3/2)×Vdc×(1/2)×MFmax

Then, the allowable torque calculation unit 34a calculates the maximum linkage magnetic 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.

FLmax＝Vmax÷ω

The allowable torque calculation unit 34a obtains an upper limit value Ctrq _ alw _ upper and a lower limit value Ctrq _ alw _ lower of the allowable torque Ctrq _ alw based on the maximum interlinkage magnetic flux FLmax and the adjusted maximum current Imax _ adj from the maximum current adjustment unit 33 a.

Fig. 11 and 12 show an example of tables as an example of upper limit value Ctrq _ alw _ upper and lower limit value Ctrq _ alw _ lower for finding the allowable torque.

Fig. 11 is a table for determining the upper limit value Ctrq _ alw _ upper of the allowable torque, and fig. 12 is a table for determining the lower limit value Ctrq _ alw _ lower of the allowable torque. In fig. 11 and 12, the horizontal axis represents the maximum interlinkage magnetic flux FLmax, and the vertical axis represents the adjusted maximum current Imax _ adj. The allowable torque calculation unit 34a obtains an upper limit value Ctrq _ alw _ upper and a lower limit value Ctrq _ alw _ lower of the allowable torque, respectively, using, for example, the tables in fig. 11 and 12.

The curves shown in fig. 11 and 12 show contour lines connecting points of the same allowable torque. The method of calculating the allowable torque is specifically described below.

In the table of the upper limit value of the allowable torque shown in fig. 11, for example, when "maximum interlinkage magnetic flux FLmax" and "adjusted maximum current Imax _ adj" are input as indicated by a broken line, the upper limit value Ctrq _ alw _ upper of the allowable torque is calculated by linear interpolation using coordinates A, B, C, D of four points at four corners of a grid including a black circle at the intersection. The same applies to the table of the lower limit value of the allowable torque shown in fig. 12.

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.

As shown in (1) to (3) below, torque command adjustment unit 28 sets the value of adjusted torque command value Ctrq _ adj.

(1) Torque command value > upper limit value of allowable torque:

Ctrq_adj＝Ctrq_alw_upper

(2) when the upper limit value of the allowable torque is larger than or equal to the lower limit value of the allowable torque:

Ctrq_adj＝Ctrq

(3) torque command value < lower limit value of allowable torque:

Ctrq_adj＝Ctrq_alw_lower

thus, the adjusted torque command value Ctrq _ adj is set, and the adjusted torque command value Ctrq _ adj is transmitted to the current command operation unit 22.

As described above, in embodiment 1, the maximum current is adjusted by using the post-compensation temperature obtained by calculating the compensation value for the temperature of the switching elements from 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, 20a to 20c, without directly using the temperature information of the switching elements 19a to 19c, 20a to 20 c. On the other hand, in patent document 1, the torque command value of the ac rotating electrical machine is adjusted by directly using the temperature information of the switching element. In this case, when a large current is passed for a short time, the temperature of the switching element may exceed the limit temperature, and thus the switching element may be damaged. In contrast, in embodiment 1, even when a large current is passed in a short time, the switching element temperature does not exceed the limit temperature, and the switching elements 19a to 19c and 20a to 20c can be prevented from being damaged.

By appropriately setting the proportional gain Kpa of the proportional regulator 54 shown in fig. 10, the temperature of the switching elements 19a to 19c, 20a to 20c can be controlled so that the compensated temperatures of the switching elements 19a to 19c, 20a to 20c do not overshoot the preset limit temperature.

Next, the operation of each of the cases where the switching elements 19a to 19c and 20a to 20c are overheat-protected and where the switching elements are overheat-protected by a conventional control method will be described by applying embodiment 1. The conventional control method described here is a case where the overheat protection operation of the switching element is performed without adding the compensation value corresponding to the state quantity of the ac rotating electric machine 18 and the switching element temperature in embodiment 1.

Fig. 13(a) to 13(d) show graphs when the switching elements 19a to 19c, 20a to 20c are overheat-protected by applying embodiment 1.

The horizontal axes of all the graphs shown in fig. 13(a) to 13(d) represent time. The vertical axis of the graph shown in fig. 13(a) represents the actual switching element temperature, the vertical axis of the graph shown in fig. 13(b) represents the switching element temperature obtained by the temperature detection element, the vertical axis of the graph shown in fig. 13(c) represents the post-switching element compensation temperature, the vertical axis of the graph shown in fig. 13(d) represents the switching element temperature compensation value, and the vertical axis of the graph shown in fig. 13(e) represents the phase current detection value.

Fig. 14(a) to 14(c) show graphs when the switching element is overheat-protected by a conventional control method.

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

In the conventional control method shown in fig. 14(a) to 14(c), the phase current detection value takes the upper limit value by applying the maximum torque immediately after the start. Accordingly, the switching element temperature obtained by the temperature detection element shown in fig. 14(b) rises and reaches the limit temperature. At this moment, the phase current detection value shown in fig. 14(c) starts to decrease. That is, the current flowing through the ac rotating electric machine 18 is reduced, and thereby the overheat protection operation of the switching element is started. However, the actual switching element temperature shown in fig. 14(a) overshoots and exceeds the limit temperature before the switching element temperature detected by the temperature detection element reaches the limit temperature. This overshoot can be eliminated by lowering the limit temperature for starting the overheat protection, but since setting the limit temperature always low leads to excessively limiting the energization current due to the overheat protection, the output is excessively lowered.

Next, a case where the switching elements 19a to 19c, 20a to 20c are overheat-protected by the control method of embodiment 1 shown in fig. 13(a) to 13(e) will be described.

In the control method according to embodiment 1 shown in fig. 13(a) to 13(e), the phase current detection value becomes the upper limit value by applying the maximum torque immediately after the start. Accordingly, the switching element temperature obtained by the temperature detection element shown in fig. 13(b) rises. Further, the switching element temperature compensation value shown in fig. 13(d) increases as the phase current detection value increases, and the upper limit value is set. This means that in embodiment 1, the compensation value corresponding to the state quantity of the ac rotating electrical machine 18 is calculated. The post-switching-element-compensation temperature of fig. 13(c) is obtained by adding the calculated compensation value to the switching element temperature obtained by the temperature detection element of fig. 13 (b). The overheating protection of the switching elements 19a to 19c, 20a to 20c is performed in accordance with the temperature compensated by the switching elements. Therefore, as shown in fig. 13(a) to 13(e), when the temperature reaches the limit temperature after the switching element compensation, the overheat protection is started, and the phase current detection value is decreased. The timing is before the timing at which the switching element temperature obtained by the temperature detecting element reaches the limit temperature.

Accordingly, since the overheat protection of the switching elements 19a to 19c and 20a to 20c is started early, the overheat protection can be performed when the actual switching element temperature does not exceed the limit temperature as shown in fig. 13 (a). That is, the control method of embodiment 1 can reduce the maximum temperature of the switching elements 19a to 19c, 20a to 20c exceeding the limit temperature in the conventional control method.

In fig. 13(a) to 13(e), when attention is paid to the switching element temperature compensation values after the start of the overheat protection operation of the switching elements 19a to 19c and 20a to 20c, it is known that the switching element temperature compensation values converge to "0" with the elapse of time. This means that when the current flowing through the ac rotating electric machine 18 is lower than the prescribed 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 predetermined phase current detection value Ia after the maximum temperature of the switching elements 19a to 19c, 20a to 20c, which is generated immediately after the large current conduction is instructed, it is not necessary to add the compensation value to the switching element temperature, and excessive output limitation can be avoided.

Embodiment 2.

Next, a control device for an ac rotating electric machine according to embodiment 2 will be described with reference to fig. 15.

Fig. 15 is a diagram obtained by replacing the phase current detection value calculation section 29a of fig. 3 of embodiment 1 with the phase current command value calculation section 29b, and reference numeral 17b denotes an overheat protection and torque command section. In embodiment 2, points different from those in embodiment 1 will be described, and the same portions will be denoted by the same reference numerals and description thereof will be omitted.

The present embodiment differs from embodiment 1 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.

The phase current command value calculation unit 29b calculates an effective value Ciuvw _ rms of a phase current to be commanded to the ac rotating electric machine 18, using the d-axis current command value Cid and the q-axis current command value Ciq in fig. 1. The calculated phase current command value Ciuvw _ rms is output to the switching element temperature compensation value calculation unit 30 b.

The switching element temperature compensation value calculation unit 30b calculates a compensation value for the switching element temperature from the phase current command value Ciuvw _ rms, which is a state quantity of the ac rotating electric machine 18. Fig. 16 shows a variation of the switching element temperature compensation value with respect to the phase current command value Ciuvw _ rms. The calculation of the compensation value is performed by replacing the phase current detection value iuvw _ rms, which is the state quantity of the ac rotating electric machine 18 in embodiment 1, with the phase current command value Ciuvw _ rms.

The predetermined phase current command value Ci _ a and the upper limit value Tcu of the switching element temperature compensation value are set from the same viewpoint as that of embodiment 1. That is, when the compensation of the switching element temperature is not performed, the maximum phase current command value not exceeding the limit temperature of the switching elements 19a to 19c, 20a to 20c is set as the predetermined phase current command value Ci _ a.

The upper limit value Tcu of the switching element temperature compensation value is set to a temperature decrease required to reduce the switching element temperature to a temperature equal to or lower than the limit temperature of the switching element temperature when the maximum phase current command value Ci _ b for controlling the ac rotating electrical machine 18 is instructed.

Embodiment 3.

Next, a control device for an ac rotating electric machine according to embodiment 3 will be described with reference to fig. 17.

Fig. 17 is a diagram obtained by replacing the phase current detection value calculation unit 29a of fig. 3 of embodiment 1 with a torque command value (after adjustment) 29c, and reference numeral 17c denotes an overheat protection and torque command unit. In embodiment 3, points different from those in embodiment 1 will be described, and the same portions will be denoted by the same reference numerals and the description thereof will be omitted.

The present embodiment differs from embodiment 1 in that the adjusted torque command value is used as the state quantity of the ac rotating electric machine 18. Here, the adjusted torque command value is used to use the torque actually instructed to the ac rotating electrical machine 18. Next, the torque command value (after adjustment) 29c will be described.

The torque command value (after adjustment) 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 which is the output of the torque command adjusting 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 30 c.

The switching element temperature compensation value calculation unit 30c calculates a compensation value for the switching element temperature from the adjusted torque command value Ctrq _ adj that is the state quantity of the ac rotating electric machine 18. Fig. 18 shows an example of transition of the switching element temperature compensation value with respect to the adjusted torque command value Ctrq _ adj. 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 embodiment 1, with the adjusted torque command value Ctrq _ adj.

From the same viewpoint as embodiment 1, the predetermined torque command value Ctrq _ a and the upper limit value Tcu of the switching element temperature compensation value are set. That is, when the compensation for the switching element temperature is not performed, 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 predetermined torque command value Ctrq _ a. The upper limit value Tcu of the switching element temperature compensation value is set to a minimum value of a temperature drop amount required for the switching element temperature to be equal to or lower than the limit temperature of the switching element when the commanded maximum torque command Ctrq _ b is applied to the ac rotating electrical machine 18 during control.

Embodiment 4.

Next, a control device for an ac rotating electric machine according to embodiment 4 will be described with reference to fig. 19.

Fig. 19 is a diagram obtained by replacing the phase current detection value calculation section 29a of fig. 3 of embodiment 1 with a torque estimation value calculation section 29d, and reference numeral 17d denotes an overheat protection and torque command section. In embodiment 4, points different from those in embodiment 1 will be described, and the same parts will be denoted by the same reference numerals, and description thereof will be omitted.

The present embodiment differs from embodiment 1 in that an estimated torque value is used as the state quantity of the ac rotating electric machine 18. Next, the torque estimation value calculation unit 29d will be explained.

The torque estimation value calculation unit 29d estimates the torque output by the ac rotating electrical machine 18 by calculation. For example, the torque output by the ac rotating electrical machine 18 can be estimated by calculating the mechanical output by the ac rotating electrical machine 18 and dividing the mechanical output by the mechanical angular velocity of the ac rotating electrical machine 18.

Here, an example of the operation machine output will be described. The inverter input power is calculated by multiplying the direct-current voltage Vdc of the direct-current power supply 10 by the current flowing from the direct-current power supply 10 to the inverter 12. Then, the inverter input power is multiplied by the power conversion efficiency of the inverter 12, thereby calculating the inverter output power. Then, the mechanical output is obtained by subtracting the loss of the ac rotating electrical machine 18 from the inverter output power. At this time, the power conversion efficiency of the inverter 12 and the loss of the ac rotating electrical machine 18 vary depending on the operating state of the ac rotating electrical machine 18, and therefore a MAP (hereinafter referred to as MAP) corresponding to the operating state is stored in the control device of the inverter 12. Since the method of calculating the torque estimate is well known, a detailed description thereof will be omitted. Other estimation algorithms may be used to estimate the torque of the ac rotating machine 18. The calculated torque estimation value Etrq is output to the switching element temperature compensation value calculation unit 30 d.

The switching element temperature compensation value calculation unit 30d calculates a compensation value for the switching element temperature from the torque estimation value Etrq, which is the state quantity of the ac rotating electrical machine 18. Fig. 20 shows a variation of the switching element temperature compensation value with respect to the torque estimation value Etrq. The calculation of the compensation value is performed by replacing the phase current detection value iuvw _ rms, which is the state quantity of the ac rotating electric machine 18 in embodiment 1, with the torque estimation value Etrq.

The predetermined torque estimation value Etrq _ a and the upper limit value Tcu of the switching element temperature compensation value are set from the same viewpoint as that of embodiment 1. That is, when the compensation for the switching element temperature is not performed, the maximum torque estimation value that does not exceed the limit temperature of the switching elements 19a to 19c, 20a to 20c is set to the predetermined torque estimation value Etrq _ a. The upper limit value Tcu of the switching element temperature compensation value is set to a minimum value of a temperature decrease amount required for the switching element temperature to be equal to or lower than the limit temperature of the switching element temperature when the maximum torque Etrq _ b that can be output by the ac rotating electrical machine 18 is applied during control.

Embodiment 5.

Next, a control device for an ac rotating electric machine according to embodiment 5 will be described with reference to fig. 21.

Fig. 21 is a diagram in which the control amount adjusting unit 33 is replaced with the allowable torque control amount calculating unit 33b in the overheat protection and torque command unit 17 of fig. 1 of embodiment 1, and reference numeral 17e denotes the overheat protection and torque command unit. In embodiment 5, points different from those in embodiment 1 will be described, and the same portions are denoted by the same reference numerals, and description thereof will be omitted.

The present embodiment differs from embodiment 1 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.

Next, the allowable torque control amount calculation unit 33b will be described.

The allowable torque control amount calculation unit 33b adjusts the control amount Kc based on the temperature deviation Δ T between the switching element compensated temperature and the limit temperatures of the switching elements 19a to 19c, 20a to 20c, and outputs the adjusted control amount Kc _ adj. That is, this corresponds to the case where the adjusted control amount Cadj in fig. 1 is replaced with the adjusted control amount Kc _ adj. The adjusted control amount Kc _ adj takes a value from "0" to "1" and is output to the allowable torque calculation unit 34 b.

The allowable torque control amount calculation unit 33b adjusts the value of the control amount Kc so that the post-switching element compensation temperature does not exceed the preset limit temperature of the switching elements 19a to 19c, 20a to 20 c. This can suppress the overshoot of the switching element temperature with respect to the preset limit temperature, and prevent the switching elements 19a to 19c and 20a to 20c from being damaged by overheating.

Fig. 22 shows a configuration example of the allowable torque control amount calculation unit 33 b. In the configuration example of fig. 22, the allowable torque control amount calculation unit 33b includes a proportional regulator 58, an integral regulator 59, and an upper and lower limit limitation unit 60. The allowable torque control amount calculation unit 33b receives a temperature deviation Δ T between a preset limit temperature and the switching element compensated temperature as input. The temperature deviation Δ T is a value obtained by subtracting the temperature compensated by the switching element from the limit temperature. Therefore, when the temperature after the switching element compensation exceeds the limit temperature, the value of the temperature deviation Δ T becomes a negative value. Therefore, in this case, the higher the temperature after the switching element compensation, the smaller the value of the temperature deviation Δ T.

In the configuration example of fig. 22, the proportional gain Kpb of the proportional regulator 58 is a positive value. The proportional regulator 58 outputs a value obtained by multiplying the input deviation by a proportional gain Kpb. The integration adjuster 59 sets the initial value to "1", and integrates the output of the proportional adjuster 58.

In the configuration example of fig. 22, when the temperature after the switching element compensation is higher than the limit temperature, the output of the proportional regulator 58 becomes a negative value, and the output of the integral regulator 59 decreases accordingly. Specifically, when the temperature after the compensation of the switching element is higher than the limit temperature, the temperature deviation Δ T becomes a negative value. The proportional regulator 58 outputs a value obtained by multiplying the temperature deviation Δ T by a proportional gain Kpb. Therefore, when the temperature deviation Δ T is a negative value, the output of the proportional regulator 58 becomes a negative value. Further, since the integration adjuster 59 integrates a negative value, the output of the integration adjuster 59 gradually decreases from the initial value. On the other hand, when the temperature after the switching element compensation is equal to or lower than the limit temperature, the output of the proportional regulator 58 becomes a positive value, and the output of the integral regulator 59 increases accordingly. In the configuration example of fig. 22, the output of the proportional regulator 58 is added to the output of the integral regulator 59 by the adder 61. The output of the adder 61 is an output value of the proportional adjustment and the integral adjustment. As described above, the temperature deviation Δ T is subjected to proportional adjustment and integral adjustment by the proportional adjuster 58 and the integral adjuster 59.

In the configuration example of fig. 22, next, the upper and lower limit limiting section 60 performs upper and lower limit limiting on the output values of the scale adjustment and the 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 section 60 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 control amount Kc _ adj.

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 section 60. When the addition result is equal to or smaller than the upper limit value and equal to or larger than 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 larger than the upper limit value, the upper limit value is output as the adjusted control amount Kc _ adj. When the addition result is smaller than the lower limit value, the lower limit value is output as the adjusted control amount Kc _ adj.

In the configuration example of fig. 22, the upper limit value is set to "1", and therefore the adjusted control amount Kc _ adj does not exceed "1". Further, since the lower limit value is set to "0", the adjusted control amount Kc _ adj can be prevented from becoming a negative value.

Although the configuration example of fig. 22 is shown as a configuration example of the allowable torque control amount calculation unit 33b, the control amount Kc for limiting the allowable torque may be adjusted by another method. 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 34 b.

Next, the allowable torque calculation unit 34a in fig. 21 will be described.

Fig. 23 shows an example of the structure of the allowable torque calculation unit 34 b. First, the rotational speed calculation unit 62 calculates the rotational speed N of the ac rotating electrical machine 18 using the electrical angular velocity ω calculated by the electrical angular velocity calculation unit 14. The arithmetic expression is N [ rpm ] ═ 60 × ω ÷ (2 pi p). Here, p is the number of pole pairs of the ac rotating machine 18. The calculated rotation speed N is output to the allowable torque (upper limit) MAP63 and the allowable torque (lower limit) MAP 64.

The allowable torque (upper limit) MAP63 and the allowable torque (lower limit) MAP64 output an upper limit value and a lower limit value of a torque value that can be output at that time on the MAP, respectively, based on the rotation speed N and the direct-current voltage Vdc. That is, the allowable torque (upper limit) MAP63 outputs an upper limit value Ctrq _ MAP _ upper of the torque that can be output on MAP, and the allowable torque (lower limit) MAP64 outputs a lower limit value Ctrq _ MAP _ lower of the torque that can be output on MAP.

MAPs shown as an example in fig. 24 and 25 are set in advance in the allowable torque (upper limit) MAP63 and the allowable torque (lower limit) MAP 64. As for the allowable torque (upper limit) MAP63, an upper limit value Ctrq _ MAP _ upper of the torque that can be output on MAP is obtained from the rotation speed N and the direct-current voltage Vdc using fig. 24. On the other hand, the lower limit value Ctrq _ MAP _ lower of the torque that can be output on MAP is obtained from the rotation speed N and the dc voltage Vdc using fig. 25 for the allowable torque (lower limit) MAP 64.

The control amount Kc _ adj calculated by the allowable torque control amount calculation unit 33b is multiplied by Ctrq _ MAP _ upper outputted from the allowable torque (upper limit) MAP63, and the resultant value of the multiplication is outputted to the torque command adjustment unit 28 as the upper limit value Ctrq _ alw _ upper of the allowable torque.

On the other hand, Ctrq _ MAP _ lower outputted from allowable torque (lower limit) MAP64 is multiplied by control amount Kc _ adj calculated by allowable torque control amount calculation unit 33b, and the resultant value of the multiplication is outputted to torque command adjustment unit 28 as allowable torque lower limit value Ctrq _ alw _ lower.

In embodiment 5, the upper limit value Ctrq _ alw _ upper and the lower limit value Ctrq _ alw _ lower of the allowable torque are adjusted by calculating the control amount Kc _ adj whose value is between "0" and "1" on the basis of the temperature deviation Δ T between the temperature after the switching element compensation and the limit temperature of the switching elements 19a to 19c, 20a to 20c, and multiplying the control amount Kc _ adj by the upper limit value and the lower limit value of the torque that can be output on MAP. That is, the allowable torque can be adjusted in accordance with the temperature deviation Δ T between the temperature after the switching element compensation and the limit temperature of the switching elements 19a to 19c, 20a to 20 c. After the allowable torque is adjusted, the torque command value is adjusted by the torque command adjusting section 28 of the subsequent stage, and therefore the temperature of the switching elements can be controlled to prevent the overheating of the switching elements 19a to 19c, 20a to 20 c.

The allowable torque adjusting unit 32b according to embodiment 5 may be applied instead of the allowable torque adjusting unit 32a according to embodiments 1 to 4.

When the overheat protection action is performed by the control device of the alternating-current rotary electric machine of embodiments 1 to 5, the effects listed below can be obtained.

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

As described above, in the control device of the present embodiment, the switching element temperature compensation

value calculation units

30, 30a, 30b, 30c, and 30d calculate a compensation value that is a positive value when the ac rotating electrical machine state quantity is equal to or greater than an appropriate predetermined value, and set the compensation value to "0" when the ac rotating electrical machine state quantity is equal to or less than the predetermined value. Thus, the overheat protection of the switching elements 19a to 19c and 20a to 20c does not need to be started early, and an excessive overheat protection operation can be avoided.

In addition, in the control device of the present embodiment, since the switching element temperature compensation

value calculation units

30, 30a, 30b, 30c, and 30d calculate the compensation value having a positive value in accordance with the fact that the ac rotating electric machine state quantity is an appropriate predetermined value as described above, if the ac rotating electric machine state quantity is less than the predetermined value after the maximum temperature of the switching elements 19a to 19c, 20a to 20c that occurs immediately after the large current supply is instructed, the compensation value becomes "0", and therefore, it is not necessary to add the compensation value to the switching element temperature, and it is possible to avoid excessive output limitation.

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 upper limit value Tcu of the switching element temperature compensation value appropriately, thereby setting the switching element temperature within the limit temperature that cannot be exceeded absolutely in actual use, and preventing excessive current limitation, that is, preventing output reduction.

In the control devices of embodiments 1 to 4, the maximum current adjusting section 33a can control the switching element temperature by adjusting the maximum current Imax so that the sum of the compensation values obtained by the switching element temperature compensation

value calculating sections

30, 30a, 30b, 30c, and 30d and the temperature information of the switching elements 19a to 19c, and 20a to 20c obtained by the switching element temperature obtaining section 31 does not exceed the preset limit temperature.

In the control device according to embodiment 5, the allowable torque control amount calculation unit 33b can 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, or 30d and the temperature information of the switching elements 19a to 19c, or 20a to 20c obtained by the switching element temperature acquisition unit 31 does not exceed the preset limit temperature.

In the control device of the present embodiment, the control amount of the ac rotating machine 18 is adjusted by simply adding the compensation value corresponding to the state quantity of the ac rotating machine 18 to the switching element temperature, so that the maximum temperature of the switching elements 19a to 19c, 20a to 20c can be simply lowered without performing complicated compensation or estimation. That is, the maximum temperature of the switching element temperature can be easily made within the limit temperature, and the failure of the switching elements 19a to 19c, 20a to 20c can be prevented.

In addition, each function in the control devices of embodiments 1 to 5 described above is realized by a processing circuit. The processing circuit for realizing each function may be dedicated hardware or a processor for executing a program stored in a memory.

In case the processing Circuit is dedicated hardware, the processing Circuit for example corresponds to 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 the inverter control unit 16, the switching element temperature compensation

value calculation units

30, 30a, 30b, 30c, and 30d, the control amount adjustment unit 33, the allowable

torque calculation units

34, 34a, and 34b, and the torque command adjustment unit 28 may be realized by separate processing circuits, or may be realized by a processing circuit in which the functions of the respective units are combined.

On the other hand, when the processing circuit is a processor, the functions of the respective parts of the inverter control section 16, the switching element temperature compensation

value operation sections

30, 30a, 30b, 30c, 30d, the control amount adjustment section 33, the allowable

torque operation sections

34, 34a, 34b, and the torque command adjustment section 28 are realized by software, firmware, or a combination of software and firmware. Software and firmware are represented as programs and stored in memory. The processor reads and executes the program stored in the memory, thereby implementing the functions of each part. That is, the control device includes a memory for storing a program for executing the inverter control step, the temperature compensation value operation step, the control amount adjustment step, the allowable torque operation step, and the torque command adjustment step as a result when executed by the processing circuit.

The programs may also be contents that cause a computer to execute the steps or methods of the above-described respective sections. Here, the Memory corresponds to a nonvolatile or volatile semiconductor Memory such as a RAM (Random access Memory), a ROM (Read Only Memory), a flash Memory, an EPROM (Erasable Programmable Read Only Memory), and an EEPROM (Electrically Erasable Programmable Read-Only Memory). Further, a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, a DVD, and the like also correspond to the memory.

In addition, as for the functions of the above-described respective sections, a part of the functions may be implemented by dedicated hardware, and another part of the functions may be implemented by software or firmware.

Thus, the processing circuitry may implement the functionality of the various components described above using hardware, software, firmware, or a combination thereof.

While various exemplary embodiments and examples are described herein, the various features, aspects, and functions described in one or more embodiments are not limited in their application to a particular embodiment, but may be applied to embodiments alone or in various combinations.

Therefore, countless modifications not shown by way of example can be conceived within the technical scope disclosed in the present application. For example, it is assumed that 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 the components of other embodiments are included.

Description of the reference symbols

10 dc power supply, 11 voltage detector, 12 inverter, 13 magnetic pole position detecting section, 14 electrical angular velocity calculating section, 15a to 15c current sensor, 16 inverter control section, 17a, 17b, 17c, 17d, 17e overheat protection and torque command section, 18 ac rotating electrical machine, 19a to 19c, 20a to 20c switching element, 21 three-phase to two-phase current converting section, 22 current command calculating section, 23d axis current controller, 24q axis current controller, 25 two-phase to three-phase voltage converting section, 26PWM circuit, 27 gate driver, 28 torque command adjusting section, 29 ac rotating electrical machine state quantity acquiring section, 29a phase current detecting value calculating section, 29b phase current command value calculating section, 29c torque command value (after adjustment), 29d torque estimation value calculating section, 30a, 30b, 30c, 30d switching element temperature compensation value calculating section, A 31 switching element temperature acquisition unit, 32a, 32b allowable torque adjustment unit, 33 control amount adjustment unit, 33a maximum current adjustment unit, 33b allowable torque control amount calculation unit, 34a, 34b allowable torque calculation unit, 50 temperature detection element, 51 substrate, 52 effective region, near the center of 53, 54, 58 proportional regulator, 55, 59 integral regulator, 56, 61 adder, 57, 60 upper and lower limit limiting unit, 62 rotation 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 to D3, D4 to D6 rectifying element, Uac, Vac, and Wac connection node.

Claims

1. A control device for an ac rotating machine, comprising:

a switching element temperature acquisition section that is connected to a power conversion circuit for driving an alternating-current rotary electric machine, and that acquires temperature information of a switching element of the power conversion circuit;

an ac rotating machine state quantity acquisition unit that acquires a state quantity of the ac rotating machine;

a switching element temperature compensation value calculation unit that calculates a compensation value for a switching element temperature based on a state quantity of the ac rotating electrical machine; and

and an allowable torque adjustment unit that adjusts the torque that can be output by the ac rotating electrical machine 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.

2. The control device of an alternating-current rotary electric machine according to claim 1,

the state quantity is any one of a detected quantity of current flowing through the ac rotating electrical machine, a command quantity of current flowing through the ac rotating electrical machine, an estimated quantity of torque output by the ac rotating electrical machine, and a command quantity of torque output by the ac rotating electrical machine.

3. The control device of an alternating-current rotary electric machine according to claim 1,

the state quantity is determined using two or more of a detected quantity of current flowing through the ac rotating electrical machine, a command quantity of current flowing through the ac rotating electrical machine, an estimated quantity of torque output by the ac rotating electrical machine, and a command quantity of torque output by the ac rotating electrical machine.

4. The control device of an alternating-current rotary electric machine according to any one of claims 1 to 3,

the temperature information of the switching element is a detected amount of the temperature of the switching element.

5. The control device of an alternating-current rotary electric machine according to any one of claims 1 to 3,

the temperature information of the switching element is an estimated amount of the temperature of the switching element.

6. The control device of an alternating-current rotary electric machine according to any one of claims 1 to 5,

the allowable torque adjustment unit includes: a control amount adjusting unit for adjusting a control amount of the ac rotating machine; and an allowable torque calculation unit for calculating a torque that can be output by the ac rotating electrical machine, whereby the allowable torque adjustment unit adjusts the allowable torque.

7. The control device of an alternating-current rotary electric machine according to claim 6,

the control amount adjustment unit adjusts a maximum value of a current that energizes the ac rotating electric machine.

8. The control device of an alternating-current rotary electric machine according to any one of claims 1 to 7,

the switching element temperature compensation value calculation unit outputs zero when the state quantity of the ac rotating electric machine is equal to or less than a predetermined value, and outputs a positive value according to the state quantity of the ac rotating electric machine with an upper limit compensation value as an upper limit when the state quantity of the ac rotating electric machine is greater than the predetermined value.

9. The control device of an alternating-current rotary electric machine according to claim 8,

the predetermined value is set to a maximum value of: 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.

10. The control device of an alternating-current rotary electric machine according to claim 8 or 9,

the upper limit compensation value is set to a minimum value of a temperature drop amount by which the temperature information of the switching element becomes equal to or less than a limit temperature of the switching element.