AC rotating electric machine control device

A control device for an AC rotating electric machine includes: a temperature detection unit configured to detect a temperature of a protection part; a maximum current adjustment unit configured to adjust a maximum current of an AC rotating electric machine so as to prevent the temperature of the protection part from exceeding a set temperature; an allowable torque calculation unit configured to calculate an allowable torque based on the maximum current adjusted; a torque command adjustment unit configured to adjust a torque command value directed to the AC rotating electric machine based on the allowable torque; an upper limit number-of-rotation calculation unit configured to calculate an upper-limit number of rotations of the AC rotating electric machine based on the maximum current adjusted; and a number-of-rotation adjustment unit configured to adjust the number of rotations of the AC rotating electric machine based on the upper-limit number of rotations.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a National Stage of International Application No. PCT/JP2018/035431 filed on Sep. 25, 2018.

TECHNICAL FIELD

The present invention relates to a control device for an AC rotating electric machine.

BACKGROUND ART

In general, an electrically driven vehicle, for example, an electric vehicle or a hybrid vehicle, is mounted with an AC rotating electric machine as a drive source for the vehicle. Moreover, a power conversion device connected to the AC rotating electric machine has a power converting function of converting DC power to AC power in order to supply DC power received from a DC power source to the AC rotating electric machine. Accordingly, the power conversion device is provided with a power conversion circuit formed of switching devices, for example, metal-oxide-semiconductor field-effect transistors (MOSFETs).

Normally, when a temperature of each of the switching devices, for example, the MOSFETs reaches a temperature exceeding a predetermined junction temperature Tj, junction breakdown may occur therein to break down the switching device. Moreover, the AC rotating electric machine may also break down when its temperature exceeds a given temperature. Accordingly, it is required to inhibit a temperature increase so as to prevent the temperature of each of the switching devices and the AC rotating electric machine from exceeding the temperature defined for each thereof in order to protect the switching devices and the AC rotating electric machine from excessive heat.

For example, according to a related-art electric motor control device disclosed in Patent Literature 1, there has been proposed a method involving detecting a temperature of a power semiconductor device and correcting a torque command value so as to eliminate a deviation between the detected temperature and a set temperature.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

In general, as an AC rotating electric machine to be driven through use of an inverter, a permanent magnet synchronous motor is widely used. As a method of controlling the permanent magnet synchronous motor, two control methods, namely, maximum torque control and flux weakening control, are known. The maximum torque control performs torque control so that a maximum torque can be obtained at an early stage of acceleration.

As an angular speed of the permanent magnet synchronous motor increases, an inductive voltage generated from the permanent magnet synchronous motor also increases. The inductive voltage is applied to both terminals of the DC power source connected to the permanent magnet synchronous motor. When the inductive voltage reaches a limit value of a voltage across the terminals of the DC power source, the control method is changed from the maximum torque control to the flux weakening control.

The flux weakening control reduces field magnetic fluxes to suppress an increase in inductive voltage. In this case, a magnetic field of the permanent magnet synchronous motor cannot directly be weakened, and hence, a negative current is caused to flow in a d-axis armature to cause a d-axis armature reaction, to thereby generate a demagnetization effect.

However, in Patent Literature 1, the negative current flowing through the d-axis armature is not considered, and only the torque command value is simply corrected. Therefore, a current above the allowable value may flow to each switching device in a high-rotation region even when the torque command value is set to zero. As a result, the temperature of each switching device becomes a temperature above the set temperature, and the switching device may thus break down.

The present invention has been made to solve such a problem, and has an object to provide a control device for an AC rotating electric machine capable of preventing a breakdown of a switching device caused by excessive heat.

Solution to Problem

According to one embodiment of the present invention, there is provided a control device for an AC rotating electric machine including: a temperature detection unit configured to detect a temperature of a protection part (to be protected), the temperature increasing in proportion to an increase in a temperature of a switching device of a power conversion circuit connected to the AC rotating electric machine; a maximum current adjustment unit configured to adjust a maximum current of the AC rotating electric machine so as to prevent the temperature of the protection part detected by the temperature detection unit from exceeding a set temperature set in advance; an allowable torque calculation unit configured to calculate an allowable torque based on the maximum current adjusted by the maximum current adjustment unit; a torque command adjustment unit configured to adjust a torque command value directed to the AC rotating electric machine based on the allowable torque; an upper limit number-of-rotation calculation unit configured to calculate an upper-limit number of rotations of the AC rotating electric machine based on the maximum current adjusted by the maximum current adjustment unit; and a number-of-rotation adjustment unit configured to adjust the number of rotations of the AC rotating electric machine based on the upper-limit number of rotations.

Advantageous Effects of Invention

The control device for an AC rotating electric machine according to the present invention can prevent the breakdown of the switching device caused by the excessive heat.

DESCRIPTION OF EMBODIMENTS

Now, referring to the drawings, a control device for an AC rotating electric machine according to a preferred embodiment of the present invention is described.

First Embodiment

FIG. 1is a configuration diagram for illustrating a control device for an AC rotating electric machine according to a first embodiment of the present invention. The control device is configured to control an AC rotating electric machine30. As illustrated inFIG. 1, the control device includes a DC power source10, a voltage detection unit11, an inverter20, a magnetic pole position detection unit31, an electric angular speed detection unit32, current sensors33ato33c, an inverter control unit40, a temperature detection unit50, a maximum current adjustment unit51, an allowable torque calculation unit52, an upper limit number-of-rotation calculation unit53, a number-of-rotation adjustment unit54, and a torque command adjustment unit55.

Description is given below of the individual units of the control device illustrated inFIG. 1.

The DC power source10is a chargeable/dischargeable power source. The DC power source10is configured to supply and receive electric power to and from the AC rotating electric machine30via the inverter20. The DC power source10includes a higher-voltage node P and a lower-voltage node N. The DC power source10and the inverter20are connected via the higher-voltage node P and the lower-voltage node N. It may also be possible to provide a boost converter between the DC power source10and the inverter20to boost the DC voltage supplied from the DC power source10by DC/DC conversion. It may also be possible to connect a smoothing capacitor configured to smooth a DC voltage between the higher-voltage node P and the lower-voltage node N.

The voltage detection unit11is configured to detect a DC voltage Vdc from the DC power source10. Specifically, the voltage detection unit11is configured to measure a terminal-to-terminal voltage between the higher-voltage node P and the lower-voltage node N, and to output the measured terminal-to-terminal voltage as the DC voltage Vdc.

As illustrated inFIG. 1, the inverter20includes a power conversion circuit including upper-arm power semiconductor devices21ato21cand lower-arm power semiconductor devices22ato22c. Through switching operations of the upper-arm power semiconductor devices21ato21cand the lower-arm power devices22ato22c, the inverter20converts the high DC voltage received from the DC power source10to an AC voltage by DC/AC conversion. The obtained AC voltage is applied to the AC rotating electric machine30.

In the inverter20, each of the power semiconductor devices21ato21cand22ato22cis formed by connecting a semiconductor switching device and a semiconductor rectifier device to each other in antiparallel. Accordingly, a set of the semiconductor switching device and the semiconductor rectifier device is one unit forming each power semiconductor device. As the connection method for the semiconductor switching device and the semiconductor rectifier device, for example, a cathode electrode of the semiconductor rectifier device is connected to a collector electrode of the semiconductor switching device, and an anode electrode of the semiconductor rectifier device is connected to an emitter electrode of the semiconductor switching device. As described above, the semiconductor switching device and the semiconductor rectifier device are connected to each other in antiparallel, to thereby serve as the one unit forming the power semiconductor device.

The AC rotating electric machine30controls a driving force and a braking force for the vehicle by applying the AC voltage output from the inverter20. For example, the AC rotating electric machine30is formed of a permanent magnet synchronous motor. In the first embodiment, as an example of the AC rotating electric machine30, description is given of an AC rotating electric machine provided with three-phase armature winding wires. However, the number of phases of the AC rotating electric machine30is not limited to three, and may be any number in total. That is, the control device according to the first embodiment can be applied to an AC rotating electric machine provided with multi-phase armature winding wires.

The magnetic pole position detection unit31is configured to detect a position of a magnetic pole in the AC rotating electric machine30. The magnetic pole position detection unit31includes a Hall device or an encoder. The magnetic pole position detection unit31is configured to detect a rotation angle of the magnetic pole relative to a reference rotation position of a rotor of the AC rotating electric machine30, and to output a signal representing a detection value of the detected rotation angle as a magnetic pole position θ. In this configuration, the magnetic pole position θ indicates a rotation angle about a q axis. Moreover, the reference rotation position of the rotor is preliminarily set appropriately to a suitable position.

The electric angular speed detection unit32is configured to detect an electric angular speed ω of the AC rotating electric machine30, and to output a signal representing the detection value of the detected electric angular speed ω as the electric angular speed. The electric angular speed detection unit32may include a Hall device or an encoder similarly to the magnetic pole position detection unit31, or may also be configured to arithmetically determine the electric angular speed ω through use of the magnetic pole position output from the magnetic pole position detection unit31.

The current sensors33ato33care configured to detect current quantities iU, iV, and iW of currents flowing in a U-phase, a V-phase, and a W-phase, respectively, in the AC rotating electric machine30, and output the detected current quantities iU, iV, and iW to a current coordinate converter47. InFIG. 1, the three current sensors are provided to detect the U-phase, V-phase, and W-phase current quantities, respectively, but the configuration is not limited to this case, and the number of the current sensors may be two. In such a configuration, the current quantities are detected in only two phases, and a current quantity in the other one phase is arithmetically determined from the detected current quantities in the two phases.

The inverter control unit40is configured to control the switching operations of the semiconductor switching devices in the upper-arm power semiconductor devices21ato21cand the lower-arm power semiconductor devices22ato22cincluded in the inverter20, and control the respective current quantities of the currents flowing through the AC rotating electric machine30by adjusting respective potentials at connection nodes Uac, Vac, and Wac between the inverter20and the AC rotating electric machine30. Description is given below of a configuration of the inverter control unit40.

As illustrated inFIG. 1, the inverter control unit40includes a current command arithmetic unit41, a d-axis current adjuster42, a q-axis current adjuster43, a voltage coordinate converter44, a pulse width modulation (PWM) circuit45, a gate driver46, and a current coordinate converter47. The inverter control unit40controls the inverter20by performing dq vector control to control rotation of the AC rotating electric machine30. Description is given below of the individual units forming the inverter control unit40.

An adjusted torque command value Ctrq_adj for specifying a torque to be generated in the AC rotating electric machine30is input from the torque command adjustment unit55to the current command arithmetic unit41. The current command arithmetic unit41is configured to arithmetically determine, based on the torque command value Ctrq_adj, a d-axis current command value Cid and a q-axis current command value Ciq, and output the d-axis current command value Cid and the q-axis current command value Ciq to the d-axis current adjuster42and the q-axis current adjuster43, respectively.

The current coordinate converter47is configured to convert the three-phase current quantities iU, iV, and iW received from the current sensors33ato33cto two-phase current quantities, namely, a d-axis current value id and a q-axis current value iq. The current coordinate converter47is configured to output the d-axis current value id and the q-axis current value iq to the d-axis current adjuster42and the q-axis current adjuster43, respectively.

The d-axis current adjuster42is configured to arithmetically determine a DC d-axis voltage command value Cvd so that a deviation between the d-axis current command value Cid received from the current command arithmetic unit41and the d-axis current value id received from the current coordinate converter47is “0”, and to output the d-axis voltage command value Cvd to the voltage coordinate converter44.

The q-axis current adjuster43is configured to arithmetically determine a DC q-axis voltage command value Cvq so that a deviation between the q-axis current command value Ciq received from the current command arithmetic unit41and the q-axis current value iq received from the current coordinate converter47is “0”, and output the q-axis voltage command value Cvq to the voltage coordinate converter44.

The voltage coordinate converter44is configured to convert, based on the magnetic pole position9received from the magnetic pole position detection unit31, the two-phase DC d-axis and q-axis voltage command values Cvd and Cvq to three-phase AC voltage command values Cvu, Cvv, and Cvw, and to output the three-phase AC voltage command values Cvu, Cvv, and Cvw to the PWM circuit45.

The PWM circuit45is configured to generate control signals for controlling the respective switching devices in the upper-arm power semiconductor devices21ato21cand the lower-arm power semiconductor devices22ato22cincluded in the inverter20, and to output the control signals to the gate driver46.

The gate driver46is configured to control, based on the individual control signals received from the PWM circuit45, the switching operations of the semiconductor switching devices in the upper-arm power semiconductor devices21ato21cand the lower-arm power semiconductor devices22ato22c, to thereby perform DC/AC conversion in the inverter20.

The temperature detection unit50is configured to detect a temperature of a protection part70(to be protected). The protection part70is a member the temperature of which increases in proportion to increases in the temperature of the switching device included in each of the power semiconductor devices21ato21cand22ato22cof the inverter20, and increases in the temperatures of coils and a magnet included in the AC rotating electric machine. The protection part70is provided in order to prevent those switching devices, coils, and the magnet from breaking down due to excessive heat. Description is given below of the protection part70. When the excessive heat of the switching devices is to be prevented, the protection part70is provided, for example, on the same substrate on which the switching devices are mounted. The protection part70and the switching devices are in the same environment, and therefore the temperature of the protection part70increases in proportion to increases in the temperatures of the switching devices. Accordingly, when the temperature of the protection part70can be controlled so as not to exceed a set temperature set in advance, it is also possible to prevent the switching devices from breaking down due to the excessive heat. As described above, it is only required to provide the protection part70in the same environment as that of a member to be prevented from being excessively heated, but the configuration is not limited to this example. The temperature detection unit50includes a temperature sensor or the like, and directly detects the temperature of the protection part70. Alternatively, the temperature detection unit50obtains an estimated value of the temperature of the protection part70by using predetermined calculations. In such a case, for example, the temperature detection unit50calculates the estimated value of the temperature of the protection part70by using an calculation according to an estimation algorithm for estimating the junction temperature. The estimation algorithm for estimating the junction temperature is publicly known, and description thereof is therefore omitted. Moreover, other estimation algorithms may be used to estimate the temperature of the protection part70.

The maximum current adjustment unit51is configured to adjust a maximum current Imax based on the temperature of the protection part70detected by the temperature detection unit50, and to output an adjusted maximum current Imax_adj. The maximum current adjustment unit51is configured to adjust the value of the maximum current Imax based on the temperature of the protection part70so that the temperature of the protection part70detected by the temperature detection unit50does not exceed the set value set in advance. With this configuration, the increases in the temperatures of the switching devices of the inverter20are suppressed, to thereby be able to prevent the switching devices from breaking down due to the excessive heat. With reference toFIG. 3toFIG. 8, description is later given of a specific configuration and operation of the maximum current adjustment unit51.

The allowable torque calculation unit52is configured to calculate an allowable torque Ctrq_alw based on the adjusted maximum current Imax_adj output from the maximum current adjustment unit51. Description is later given of a calculation method for the allowable torque Ctrq_alw by the allowable torque calculation unit52.

Description is now given of the maximum current Imax_adj to be output by the maximum current adjustment unit51. The maximum current Imax_adj is a maximum value allowed at the present time for a phase current absolute value given by Expression (1).

For example, when the adjusted maximum current Imax_adj output from the maximum current adjustment unit51is 500 A, the allowable torque calculation unit52calculates a torque at which the phase current absolute value is the maximum under a condition that which the phase current absolute value is equal to or smaller than 500 A. Accordingly, when the torque command value within a range of the allowable torque is input, the d-axis current command value Cid and the q-axis current command value Ciq, which are output from the current command arithmetic unit41, basically satisfy a condition given by Expression (2).

The d-axis current and the q-axis current are feedback-controlled to the command values. Accordingly, by setting each of absolute values of the d-axis current command value and the q-axis current command value to a value equal to or smaller than the maximum current Imax_adj, it is also possible to control the phase current absolute value to a value equal to or smaller than the maximum current.

The upper limit number-of-rotation calculation unit53is configured to calculate an upper-limit number of rotations Crot_lim based on the adjusted maximum current Imax_adj output from the maximum current adjustment unit51. Description is later given of a calculation method for the upper-limit number of rotations Crot_lim by the upper limit number-of-rotation calculation unit53.

The number-of-rotation adjustment unit54is configured to adjust the number of rotations Rot of the AC rotating electric machine30based on the upper limit number-of-rotation Crot_lim output from the upper limit number-of-rotation calculation unit53. The number-of-rotation adjustment unit54outputs a control command value for suppressing the number or rotations Rot when the number of rotations Rot of the AC rotating electric machine30has reached the upper-limit number of rotations Crot_lim. Description is later given of the control command value.

The torque command adjustment unit55is configured to adjust the torque command value Ctrq for the AC rotating electric machine30so that the torque command value Ctrq is within a range of the allowable torque Ctrq_alw output from the allowable torque calculation unit52. The torque command adjustment unit55is configured to output the adjusted torque command value Ctrq_adj to the current command arithmetic unit41. Moreover, when the torque command adjustment unit55receives a torque control command value Ctrq_lim for setting the torque command value to “0” from the number-of-rotation adjustment unit54, the torque command adjustment unit55sets the adjusted torque command value Ctrq_adj to “0”, and outputs the adjusted torque command value Ctrq_adj to the current command arithmetic unit41.

With reference to a flow chart ofFIG. 2, description is given below of operations of the maximum current adjustment unit51, the allowable torque calculation unit52, the upper limit number-of-rotation calculation unit53, the number-of-rotation adjustment unit54, and the torque command adjustment unit55of the control device illustrated inFIG. 1.

First, in Step S100, the control by the control device illustrated inFIG. 1is started.

In Step S101, the temperature of the protection part70is obtained by the temperature detection unit50. Simultaneously, in Step S102and Step S103, the torque command value Ctrq and the number of rotations Rot of the AC rotating electric machine30are obtained, respectively.

Then, in Step S104, a temperature deviation ΔT between the detected temperature obtained in Step S101and the set temperature set in advance is calculated by a subtractor, and the control proceeds to Step S105.

In Step S105, the maximum current Imax is adjusted by the maximum current adjustment unit51based on the temperature deviation ΔT. The maximum current adjustment unit51adjusts the maximum current Imax so that the temperature of the protection part70does not exceed the set temperature based on the temperature deviation ΔT. The maximum current adjustment unit51includes a proportional adjuster60and an integral adjuster61. The maximum current adjustment unit51is configured, for example, as one of three configuration examples ofFIG. 3toFIG. 5described below.

InFIG. 3, a configuration of a first configuration example of the maximum current adjustment unit51is illustrated. In the first configuration example ofFIG. 3, the maximum current adjustment unit51includes the proportional adjuster60, the integral adjuster61, and an upper/lower limit limiting unit62. The deviation between the set temperature set in advance and the detected temperature of the protection part70detected by the temperature detection unit50is input to the maximum current adjustment unit51. The deviation is a value obtained by subtracting the detected temperature from the set temperature. Accordingly, when the detected temperature is higher than the set temperature, the value of the deviation is a negative value. Thus, in this case, as the detected temperature increases, the value of the deviation decreases.

In the first configuration example ofFIG. 3, it is assumed that a proportional gain Kp of the proportional adjuster60is a positive value. The proportional adjuster60outputs a value obtained by multiplying the input deviation by the proportional gain Kp.

In the first configuration example ofFIG. 3, an initial value of the integral adjuster61is set to an upper limit value of the maximum current Imax, and the output of the proportional adjuster60is integrated. In this case, the upper limit value of the maximum current Imax indicates a value exhibited during a non-limitation period. The upper limit value of the maximum current Imax is a design upper limit value of the phase current absolute value given by Expression (1). The upper limit value of the maximum current Imax is a value mainly determined based on a loss occurring in the switching devices and by cooling performance, and is basically a constant value. A current having the phase current absolute value larger than the upper limit value of the maximum current Imax is not intentionally caused to flow under any condition. Meanwhile, the maximum current is the value that varies as described above. An adjustment range of the maximum current is between zero and the upper limit value of the maximum current Imax.

A reason for setting the initial value of the integral adjuster61to the upper limit value of the maximum current Imax is that the torque can be reliably output immediately after the activation of the inverter20. In the first configuration example ofFIG. 3, the maximum current is adjusted by the feedback control, and hence, after the activation, a given period of time is required before the maximum current reaches an appropriate value. Accordingly, when the initial value of the integral adjuster61is set to, for example, zero, even though the temperature of the protection part70is low and no protection is required, the maximum current immediately after the activation is a small value, and therefore a sufficient torque cannot be output. This presents a problem when, for example, an engine is started through use of the AC rotating electric machine. Meanwhile, when the initial value of the integral adjuster61is set to the upper limit value of the maximum current Imax, even after the activation of the inverter20under a state in which the temperature of the protection part70is higher than the set value, the protection can reliably be provided.

In the first configuration ofFIG. 3, when the detected temperature of the protection part70detected by the temperature detection unit50becomes higher than the set temperature, the output of the proportional adjuster60becomes a negative value, and the output of the integral adjuster61accordingly decreases. Specifically, when the detected temperature is higher than the set temperature, the deviation is a negative value. The proportional adjuster60outputs a value obtained by multiplying the deviation by the proportional gain Kp. Therefore, when the deviation is the negative value, the output of the proportional adjuster60is a negative value. Moreover, the integral adjuster61integrates the negative value, and the output of the integral adjuster61thus gradually decreases from the initial value. Meanwhile, when the detected temperature of the protection part70is equal to or lower than the set temperature, the output of the proportional adjuster60is a positive value, and the output of the integral adjuster61accordingly increases. In the configuration example ofFIG. 3, the output of the proportional adjuster60and the output of the integral adjuster61are added to each other by an adder. An output of the adder serves as an output value for proportional/integral compensation. As described above, the proportional adjuster60and the integral adjuster61perform the proportional/integral compensation for the deviation.

In the first configuration example ofFIG. 3, upper limit limitation and lower limit limitation for the output value of the proportional/integral compensation are then performed in the upper/lower limit limiting unit62. In the upper/lower limit limiting unit62, the upper limit value is set to the upper limit value of the maximum current Imax, and the lower limit value is set to “0”. The upper/lower limit limiting unit62uses the upper limit value and the lower limit value to limit the upper limit and the lower limit of the output value of the proportional/integral compensation, to thereby calculate the adjusted maximum current Imax_adj. Specifically, an addition result of the addition of the output of the proportional adjuster60and the output of the integral adjuster61by the adder is input to the upper/lower limit limiting unit62. 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/lower limit limiting unit62outputs the addition result kept unchanged as the adjusted maximum current Imax_adj. Meanwhile, when the addition result is larger than the upper limit value, the upper/lower limit limiting unit62outputs the upper limit value as the adjusted maximum current Imax_adj. Moreover, when the addition result is smaller than the lower limit value, the upper/lower limit limiting unit62outputs the lower limit value as the adjusted maximum current Imax_adj.

In the first configuration example ofFIG. 3, the upper limit value is set to the upper limit value of the maximum current Imax, and the adjusted maximum current Imax_adj does not thus exceed the upper limit value of the maximum current Imax. Moreover, the lower limit value is set to “0”, and the adjusted maximum current Imax_adj can thus be prevented from becoming a negative value.

InFIG. 4, a configuration of a second configuration example of the maximum current adjustment unit51is illustrated. In the second configuration example ofFIG. 4, the maximum current adjustment unit51includes the proportional adjuster60, the integral adjuster61, and the upper/lower limit limiting unit62. The deviation between the set temperature set in advance and the detected temperature of the protection part70detected by the temperature detection unit50is input to the maximum current adjustment unit51. Description is given below mainly of operations different from those in the first configuration example ofFIG. 3.

In the second configuration example ofFIG. 4, the initial value of the integral adjuster61is set to 1, and the proportional/integral compensation is performed by the proportional adjuster60and the integral adjuster61. Moreover, in the upper/lower limit limiting unit62, the upper/lower limit is limited is performed under a state in which the upper limit value is set to “1” and the lower limit value is set to “0”. Further, a product of the output of the upper/lower limit limiting unit62and the upper limit value of the maximum current Imax is calculated by a multiplier, and the calculation result is output as the adjusted maximum current Imax_adj. Specifically, when the addition result of the addition of the output of the proportional adjuster60and the output of the integral adjuster61by the adder is equal to or smaller than the upper limit value and equal to or larger than the lower limit value, a product of the addition result and the upper limit value of the maximum current Imax is calculated. Meanwhile, when the addition result is larger than the upper limit value, a product of the upper limit value and the upper limit value of the maximum current Imax is calculated. Moreover, when the addition result is smaller than the lower limit value, a product of the lower limit value and the upper limit value of the maximum current Imax is calculated.

In the second configuration example ofFIG. 4, the upper limit value is set to 1, and the adjusted maximum current Imax_adj does not thus exceed the upper limit value of the maximum current Imax. Moreover, the lower limit value is set to 0, and the adjusted maximum current Imax_adj can be prevented from becoming a negative value.

InFIG. 5, a configuration of a third configuration example of the maximum current adjustment unit51is illustrated. In the third configuration example ofFIG. 5, the maximum current adjustment unit51includes the proportional adjuster60, the integral adjuster61, and the upper/lower limit limiting unit62. The deviation between the set temperature set in advance and the detected temperature of the protection part70detected by the temperature detection unit50is input to the maximum current adjustment unit51. Description is given below mainly of operations different from those in the first configuration example ofFIG. 3.

In the third configuration example ofFIG. 5, the initial value of the integral adjuster61is set to “0”, and the proportional/integral compensation is performed. Moreover, in the upper/lower limit limiting unit62, the upper limit value is set to “0”, and the lower limit value is set to a value obtained by multiplying the upper limit value of the maximum current Imax by “−1”. Further, a sum of the output of the upper/lower limit limiting unit62and the upper limit value of the maximum current Imax is calculated by an adder, and the calculation result is output as the adjusted maximum current Imax_adj. Specifically, when the addition result of the addition of the output of the proportional adjuster60and the output of the integral adjuster61by the adder is equal to or smaller than the upper limit value and equal to or larger than the lower limit value, a sum of the addition result and the upper limit value of the maximum current Imax is calculated. Meanwhile, when the addition result is larger than the upper limit value, a sum of the upper limit value and the upper limit value of the maximum current Imax is calculated. Moreover, when the addition result is smaller than the lower limit value, a sum of the lower limit value and the upper limit value of the maximum current Imax is calculated.

In the third configuration example ofFIG. 5, the upper limit value is set to 0, and the adjusted maximum current Imax_adj does not thus exceed the upper limit value of the maximum current Imax. Moreover, the lower limit value is set to the value obtained by multiplying the upper limit value of the maximum current Imax by “−1”, and it is thus possible to prevent the adjusted maximum current Imax_adj from becoming a negative value.

Moreover, when a plurality of protection parts70and a plurality of temperature detection units50exist, a detected temperature most requiring the protection is selected from the detected temperatures detected by the temperature detection units50. Referring to examples ofFIG. 6toFIG. 8, description is later given of “the detected temperature most requiring the protection”. The maximum current adjustment unit51adjusts the maximum current Imax based on the selected detected temperature. InFIG. 6toFIG. 8, there are illustrated three configuration examples in which the plurality of protection parts70and the plurality of temperature detection units50exist. The configuration examples ofFIG. 6toFIG. 8are hereinafter referred to as fourth configuration example, fifth configuration example, and sixth configuration example, respectively. InFIG. 6toFIG. 8, description is given of the configuration of the first configuration example ofFIG. 3as a basic configuration of the maximum current adjustment unit51, but the basic configuration is not limited to this case, and may be that of the second configuration example ofFIG. 4or that of the third configuration example ofFIG. 5.

InFIG. 6, as the fourth configuration example, there is illustrated a configuration example in which a plurality of protection parts70and a plurality of temperature detection units50exist. In the fourth configuration example ofFIG. 6, the maximum current adjustment unit51includes the proportional adjuster60, the integral adjuster61, the upper/lower limit limiting unit62, and a minimum value calculation unit63. Each deviation between the set temperature set in advance to each protection part70and the detected temperature of each protection part70detected by each temperature detection unit50is input to the maximum current adjustment unit51.

In the fourth configuration example illustrated inFIG. 6, for each input deviation, the proportional/integral compensation is performed by the proportional adjuster60and the integral adjuster61. Moreover, the minimum value calculation unit63is configured to select the minimum output value from among the output values of the proportional/integral compensation, and to output the minimum output value. That is, “the detected temperature most requiring the protection” in this case corresponds to the smallest value among values (I1, I2, . . . , IN) input to the minimum value calculation unit63. That is, the value selected as “the detected temperature most requiring the protection” by the minimum value calculation unit63is min (I1, I2, . . . , IN). Moreover, the upper/lower limit limiting unit62adjusts the maximum current Imax by limiting the upper/lower limit of the output value received from the minimum value calculation unit63, and output the adjusted maximum current Imax_adj.

In the fourth configuration example ofFIG. 6, the upper limit value is set to the upper limit value of the maximum current Imax, and the adjusted maximum current Imax_adj does not thus exceed the upper limit value of the maximum current Imax. Moreover, the lower limit value is set to 0, and the adjusted maximum current Imax_adj can thus be prevented from becoming a negative value.

InFIG. 7, as the fifth configuration example, there is illustrated a configuration example in which a plurality of protection parts70and a plurality of temperature detection units50exist. In the fifth configuration example ofFIG. 7, the maximum current adjustment unit51includes the proportional adjuster60, the integral adjuster61, the upper/lower limit limiting unit62, and a minimum value calculation unit65. Each deviation between the set temperature set in advance to each protection part70and the detected temperature of each protection part70detected by each temperature detection unit50is input to the maximum current adjustment unit51.

In the fifth configuration example ofFIG. 7, the minimum value calculation unit65is configured to select the minimum output value from among the output values of the proportional adjusters60, and to output the minimum output value. That is, “the detected temperature most requiring the protection” in this case corresponds to the smallest value among values (Ip1, Ip2, . . . , IpN) input to the minimum value calculation unit65and the smallest value among values (ΔIi1, ΔIi2, . . . , ΔIiN) input to the minimum value calculation unit65. That is, the values selected by the minimum value calculation unit65as “the detected temperature most requiring the protection” are min (Ip1, Ip2, . . . , IpN) and min (ΔIi1, ΔIi2, . . . , ΔIiN). The integral adjuster61uses the output value min (ΔIi1, ΔIi2, . . . , ΔIiN) output from the minimum value calculation unit65to perform the integration. After that, the output value min (Ip1, Ip2, . . . , IpN) output from the minimum value calculation unit65and an output value received from the integral adjuster61are added to each other by an adder, and an addition result is output as the output value for the proportional/integral compensation. The upper/lower limit limiting unit62sets the upper limit value to the upper limit value of the maximum current Imax, and sets the lower limit value to “0”. The upper/lower limit limiting unit62uses the upper limit value and the lower limit value to limit the upper limit and the lower limit of the output value of the proportional/integral compensation to adjust the maximum current Imax, and outputs the adjusted maximum current Imax_adj.

In the fifth configuration example ofFIG. 7, the upper limit value is set to the upper limit value of the maximum current Imax, and the adjusted maximum current Imax_adj does not thus exceed the upper limit value of the maximum current Imax. Moreover, the lower limit value is set to 0, and the adjusted maximum current Imax_adj can thus be prevented from becoming a negative value.

InFIG. 8, as the sixth configuration example, there is illustrated a configuration example in which a plurality of protection parts70and a plurality of temperature detection units50exist. In the sixth configuration example ofFIG. 8, the maximum current adjustment unit51includes the proportional adjuster60, the integral adjuster61, the upper/lower limit limiting unit62, and a minimum value calculation unit66. Each temperature deviation ΔT between the set temperature set in advance to each protection part70and the detected temperature of each protection part70detected by each temperature detection unit50is input to the maximum current adjustment unit51.

In the sixth configuration example ofFIG. 8, the minimum value calculation unit66is configured to select a minimum input value from among the temperature deviations ΔT input to the maximum current adjustment unit51and to output the minimum input value. That is, “the detected temperature most requiring the protection” in this case corresponds to the smallest value among values (D1, D2, . . . , DN) input to the minimum value calculation unit66, that is, a minimum value of the values each obtained by subtracting the detected temperature from the set temperature. Accordingly, the value selected by the minimum value calculation unit66as “the detected temperature most requiring the protection” is min (D1, D2, . . . , DN). The proportional adjuster60is configured to output a value obtained by multiplying the output value of the minimum value calculation unit66by the proportional gain Kp. Moreover, the integral adjuster61is configured to integrate the output of the minimum value calculation unit66. After that, the output value of the proportional adjuster60and the output value of the integral adjuster61are added to each other by an adder. The upper/lower limit limiting unit62is configured to set the upper limit value to the upper limit value of the maximum current Imax, and to set the lower limit value to “0”. The upper/lower limit limiting unit62uses the upper limit value and the lower limit value to limit the upper limit and the lower limit of the output value of the proportional/integral compensation to adjust the maximum current Imax, and outputs the adjusted maximum current Imax_adj.

In the sixth configuration example ofFIG. 8, the upper limit value is set to the upper limit value of the maximum current Imax, and the adjusted maximum current Imax_adj does not thus exceed the upper limit value of the maximum current Imax. Moreover, the lower limit value is set to 0, and the adjusted maximum current Imax_adj can thus be prevented from becoming a negative value.

Referring back toFIG. 2, in Step S105, the maximum current adjustment unit51adjusts the maximum current Imax in one of the above-mentioned configuration examples illustrated inFIG. 3toFIG. 8, and outputs the adjusted maximum current Imax_adj, and the control then proceeds to Step S106.

In Step S106, the allowable torque calculation unit52calculates the allowable torque Ctrq_alw, and the upper limit number-of-rotation calculation unit53calculates the upper-limit number of rotations Crot_lim. Description is given below of calculation methods for the respective values.

The allowable torque calculation unit52first uses the DC voltage Vdc detected by the voltage detection unit11and a maximum modulation factor MFmax set in advance to arithmetically determine a maximum voltage Vmax based on an arithmetic expression of “Vmax=sqrt(3/2)×Vdc×(½)×MFmax”. Then, the allowable torque calculation unit52uses the maximum voltage value Vmax and the electric angular speed ω received from the electric angular speed detection unit32to arithmetically determine a maximum interlinkage magnetic flux FLmax based on an arithmetic expression of “FLmax=Vmax+w”. Moreover, the allowable torque calculation unit52obtains 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 on the adjusted maximum current Imax_adj received from the maximum current adjustment unit51. As an example of obtaining the upper limit value Ctrq_alw_upper and the lower limit value Ctrg_alw_lower of the allowable torque, an example of tables is shown inFIG. 9andFIG. 10.FIG. 9is a table for obtaining the upper limit value Ctrq_alw_upper of the allowable torque.FIG. 10is a table for obtaining the lower limit value Ctrq_alw_lower of the allowable torque. InFIG. 9andFIG. 10, 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 unit52uses, for example, the tables ofFIG. 9andFIG. 10to obtain the upper limit value Ctrq_alw_upper and the lower limit value Ctrq_alw_lower of the allowable torque, respectively.

Similarly to the allowable torque calculation unit52, the upper limit number-of-rotation calculation unit53first uses the DC voltage Vdc detected by the voltage detection unit11and the maximum modulation factor MFmax set in advance to calculate the maximum voltage Vmax based on an arithmetic expression of “Vmax=sqrt(3/2)×Vdc×(½)×MFmax”. Then, the upper limit number-of-rotation calculation unit53obtains the upper-limit number of rotations Crot_lim based on the maximum voltage Vmax and on the adjusted maximum current Imax_adj received from the maximum current adjustment unit51. As an example of obtaining the upper-limit number of rotations Crot_lim, an example of a table is shown inFIG. 11. InFIG. 11, the horizontal axis represents the adjusted maximum current Imax_adj, and the vertical axis represents the maximum voltage Vmax. The upper limit number-of-rotation calculation unit53uses, for example, the table ofFIG. 11to obtain the upper-limit number of rotations Crot_lim.

As described above, after the allowable torque calculation unit52and the upper limit number-of-rotation calculation unit53calculate the upper limit value Ctrq_alw_upper and the lower limit value Ctrq_alw_lower of the allowable torque, and the upper limit number-of-rotation Crot_lim, the control proceeds to Step S107.

In Step S107, the number-of-rotation adjustment unit54compares the upper-limit number of rotations Crot_lim calculated in Step S106and the number of rotations Rot obtained in Step S103with each other. When a relationship “Crot_lim>Rot” is satisfied, the number-of-rotation adjustment unit54determines that the number of rotations Rot is lower than the upper-limit number of rotations Crot_lim, and the control proceeds to Step S108. Meanwhile, when the relationship “Crot_lim>Rot” is not satisfied, the number-of-rotation adjustment unit54determines that the number of rotations Rot is equal to or higher than the upper-limit number of rotations Crot_lim, and the control proceeds to Step S112.

In Step S112, the number of rotations Rot has reached the upper-limit number of rotations Crot_lim, and hence the number-of-rotation adjustment unit54outputs a control command value for suppressing the number of rotations Rot. Description is given below of four control command values as examples.

As a first control command value, a torque control command value Ctrq_lim for setting the torque command to “0” is output to the torque command adjustment unit55. When the torque command adjustment unit55receives the torque control command value Ctrq_lim from the number-of-rotation adjustment unit54, the torque command adjustment unit55sets the adjusted torque command value Ctrq_adj to 0, and outputs the adjusted torque command value Ctrq_adj to the current command arithmetic unit41. As a second control command value, a gear shift control command Csft for changing a gear ratio is output to a gear shift control unit included in an electronic control unit (ECU) of the vehicle. As a third control command value, a brake control command Cbrk is output to a brake control unit included in the ECU. Moreover, when the vehicle is a hybrid vehicle, as a fourth control command value, a fuel injection control command Cstp for stopping a fuel injection is output to a fuel injection control unit included in the ECU. The number of rotations Rot of the AC rotating electric machine30is suppressed by outputting at least one control command value of the four control command values.

In Step S108, the torque command adjustment unit55compares the upper limit value Ctrq_alw_upper of the allowable torque calculated in Step S106and the torque command value Ctrq obtained in Step S102with each other. When a relationship torque command value Ctrq>upper limit value Ctrg_alw_upper of allowable torque is satisfied, the torque command adjustment unit55determines that the torque command value Ctrq is higher than the upper limit value Ctrq_alw_upper of the allowable torque, and the control proceeds to Step S109. Meanwhile, when the relationship torque command value Ctrq>upper limit value Ctrq_alw_upper of allowable torque is not satisfied, the torque command adjustment unit55determines that the torque command value Ctrq is equal to or lower than the upper limit value Ctrq_alw_upper of the allowable torque, and the control proceeds to Step S110.

In Step S110, the torque command value Ctrq is not higher than the upper limit value Ctrq_alw_upper of the allowable torque, and hence the torque command adjustment unit55compares the lower limit value Ctrq_alw_lower of the allowable torque calculated in Step S106and the torque command value Ctrq obtained in Step S102with each other. When a relationship torque command value Ctrq<lower limit value Ctrg_alw_lower of allowable torque is satisfied, the torque command adjustment unit55determines that the torque command value Ctrq is lower than the lower limit value Ctrq_alw_lower of the allowable torque, and the control proceeds to Step S109. Meanwhile, when the relationship torque command value Ctrq<lower limit value Ctrq_alw_lower of allowable torque is not satisfied, the torque command adjustment unit55determines that the torque command value Ctrq is equal to or higher than the lower limit value Ctrq_alw_lower of the allowable torque, and the control proceeds to Step S111.

In Step S111, the torque command value Ctrq is not higher than the upper limit value Ctrq_alw_upper of the allowable torque, and is not lower than the lower limit value Ctrq_alw_lower of the allowable torque, and the value kept unchanged of the torque command value Ctrq is thus output as the adjusted torque command value Ctrq_adj.

In Step S109, when it is determined that the torque command value Ctrq is higher than the upper limit value Ctrq_alw_upper of the allowable torque in Step S108, the torque command adjustment unit55adjusts the torque command value Ctrq by setting the Ctrq_adj to Ctrq_alw_upper. That is, the torque command adjustment unit55outputs the upper limit value Ctrq_alw_upper of the allowable torque as the adjusted torque command value Ctrq_adj. Meanwhile, when it is determined in Step S110that the torque command value Ctrq is lower than the lower limit value Ctrq_alw_lower of the allowable torque, the torque command adjustment unit55adjusts the torque command value Ctrq by setting the Ctrq_adj to Ctrq_alw_lower. That is, the torque command adjustment unit55outputs the lower limit value Ctrq_alw_lower of the allowable torque as the adjusted torque command value Ctrq_adj.

The content of the flow chart ofFIG. 2is summarized as described below. In the control device for an AC rotating electric machine according to the first embodiment, first, the maximum current adjustment unit51adjusts the maximum current Imax so that the temperature of the protection part70does not exceed the set temperature based on the temperature of the protection part70detected by the temperature detection unit50, and outputs the adjusted maximum current Imax_adj.

The allowable torque calculation unit52uses the tables ofFIG. 9andFIG. 10to calculate the upper limit value and the lower limit value of the allowable torque based on the adjusted maximum current Imax_adj.

The upper limit number-of-rotation calculation unit53uses the table ofFIG. 11based on the adjusted maximum current Imax_adj to calculate the upper-limit number of rotations Crot_lim.

At this time, when the number of rotations Rot of the AC rotating electric machine30is higher than the upper-limit number of rotations Crot_lim, the number-of-rotation adjustment unit54outputs the torque control command value Ctrq_lim to the torque command adjustment unit55in order to suppress the number of rotations Rot. The torque command adjustment unit55receives the torque control command value Ctrq_lim, sets the adjusted torque command value Ctrq_adj to 0, and outputs the adjusted torque command value Ctrq_adj to the current command arithmetic unit41.

Meanwhile, when the number of rotations Rot of the AC rotating electric machine30is equal to or lower than the upper-limit number of rotations Crot_lim, the torque command adjustment unit55sets the value of the adjusted torque command value Ctrq_adj as in the following cases (1) to (3).

(1) Torque command value>upper limit value of allowable torqueCtrq_adj=Ctrq_alw_upper

(2) Upper limit value of allowable torque Torque command value?Lower limit value of allowable torqueCtrq_adj=Ctrq

(3) Torque command value<lower limit value of allowable torqueCtrq_adj=Ctrq_alw_lower

As described above, in the first embodiment, the torque command value is not directly corrected, but the maximum current is adjusted. With this configuration, the allowable torque and the upper-limit number of rotations can be adjusted based on the value of the adjusted maximum current. Moreover, not only the allowable torque, but also the upper-limit number of rotations is adjusted, and hence the switching devices can reliably be protected.

In Patent Literature 1 given above, the torque command value is corrected. Therefore, in a high-rotation region, even when the torque command value is set to 0, it is required to cause the d-axis current to flow, and a current equal to or larger than a given current thus flows to the switching devices. Due to this current, the temperatures of the switching devices become temperatures equal to or higher than the set temperature, and the switching devices may thus break down. In the first embodiment, this problem is solved by the above-mentioned configuration, and the switching devices can reliably be prevented from breaking down due to the excessive heat.

InFIG. 16toFIG. 19, there are shown simulation results of the temperature of the protection part and the like obtained when the control device for an AC rotating electric machine according to the first embodiment performed the temperature control for the protection part70by adjusting the torque command value Ctrq and the number of rotations Rot in a hybrid vehicle. InFIG. 16toFIG. 19, the horizontal axes represent time. Moreover, the vertical axis ofFIG. 16represents the number of rotations of the AC rotating electric machine30. The vertical axis ofFIG. 17represents the torque of the AC rotating electric machine30and an engine torque. The vertical axis ofFIG. 18represents the detected temperature of the protection part70. The vertical axis ofFIG. 19represents the current command value and the maximum current.

Before description of the simulation results ofFIG. 16toFIG. 19, referring toFIG. 12toFIG. 15, description is given of simulation results in a related-art control device as a comparative example.

FIG. 12toFIG. 15are graphs for showing simulation results of the temperature of the protection part and the like obtained when the temperature control for the protection part70was performed by adjusting the torque command value in the hybrid vehicle in the related-art control device.

InFIG. 12toFIG. 15, the horizontal axes represent time. Moreover, inFIG. 12, the vertical axis represents the number of rotations of the AC rotating electric machine. The vertical axis ofFIG. 13represents the torque of the AC rotating electric machine and the engine torque. The vertical axis ofFIG. 14represents the detected temperature of the protection part70. The vertical axis ofFIG. 15represents the current command value and the maximum current.

In the simulation results obtained by the related-art control device shown inFIG. 12toFIG. 15, as shown inFIG. 13, the torque of the AC rotating electric machine becomes maximum by maximum torque control immediately after a start, and, after that, the torque command value is suppressed by flux weakening control. Moreover, as shown inFIG. 14, the torque command value becomes 0 as a result of elimination of the deviation between the detected temperature of the protection part70and the set temperature, and, as shown inFIG. 13, the torque of the AC rotating electric machine also becomes “0”. However, the engine torque is not suppressed, and, as shown inFIG. 12, the number of rotations of the AC rotating electric machine30thus continues to increase. As a result, as shown inFIG. 14, the detected temperature of the protection part70exceeds the set temperature due to a negative d-axis current by the flux weakening control.

In contrast, in the simulation results by the control device according to the first embodiment shown inFIG. 16toFIG. 19, as shown inFIG. 17, the torque of the AC rotating electric machine becomes maximum by the maximum torque control immediately after the start, and, after that, the torque command value is suppressed by the flux weakening control. Moreover, the torque command value becomes 0 as a result of the elimination of the deviation between the detected temperature of the protection part70and the set temperature, and the torque of the AC rotating electric machine also becomes “0”.

At this time, in the first embodiment, when the number of rotations Rot of the AC rotating electric machine30reaches the upper-limit number of rotations Crot_lim as shown inFIG. 16, by outputting the fuel injection control command Cstp for stopping the fuel injection to the fuel injection control, the engine torque is also brought to “0” as shown inFIG. 17, and the number of rotations Rot of the AC rotating electric machine30is suppressed as shown inFIG. 16. With this configuration, in the first embodiment, the negative d-axis current by the flux weakening control can be suppressed. As a result, as shown inFIG. 18, the detected temperature of the protection part70does not exceed the set temperature.

As apparent from the description given above, effects listed below are provided in the control device according to the first embodiment.

In the control device according to the first embodiment, the allowable torque and the upper-limit number of rotations are calculated by adjusting the maximum current based on the temperature detected by the temperature detection unit50. Moreover, the temperature of the protection part70can be controlled by adjusting the torque command value and the number of rotations based on the calculated allowable torque and on the calculated upper-limit number of rotations. As a result, the switching devices can be prevented from breaking down due to the excessive heat.

Moreover, in the control device according to the first embodiment, the maximum current adjustment unit51adjusts the maximum current so that the temperature obtained from the temperature detection unit50does not exceed the set temperature set in advance, thereby the temperature of the protection part70can be controlled.

Moreover, in the control device according to the first embodiment, the allowable torque calculation unit52calculates the allowable torque based on the maximum current adjusted by the maximum current adjustment unit51, on the DC voltage detected by the voltage detection unit11, on the maximum modulation factor set in advance, and on the electric angular speed detected by the electric angular speed detection unit32, thereby the temperature of the protection part70can be controlled.

Moreover, in the control device according to the first embodiment, the upper limit number-of-rotation calculation unit53calculates the upper-limit number of rotations based on the maximum current adjusted by the maximum current adjustment unit51, on the DC voltage detected by the voltage detection unit11, and on the maximum modulation factor set in advance, thereby the temperature of the protection part70can be controlled.

Moreover, in the control device according to the first embodiment, the number-of-rotation adjustment unit54outputs the gear shift command value to adjust the number of rotations of the AC rotating electric machine, thereby the temperature of the protection part70can be controlled.

Moreover, in the control device according to the first embodiment, the number-of-rotation adjustment unit54outputs a brake command value to adjust the number of rotations of the AC rotating electric machine, thereby the temperature of the protection part70can be controlled.

Moreover, in the control device according to the first embodiment, the number-of-rotation adjustment unit54adjusts the number of rotations of the AC rotating electric machine by outputting a fuel injection stop command value, thereby the temperature of the protection part70can be controlled.

Moreover, in the control device according to the first embodiment, the number-of-rotation adjustment unit54adjusts the number of rotations of the AC rotating electric machine by outputting the torque control command value, thereby the temperature of the protection part70can be controlled.

In the control device according to the first embodiment, when at least two protection parts70are provided, the maximum current adjustment unit51adjusts the maximum current based on the detected temperature of the protection part70most requiring the protection, thereby the temperatures of all of the protection parts70can be controlled.

Each of the functions of the control device according to the first embodiment described above is implemented by a processing circuit. The processing circuit for implementing each of the functions may be dedicated hardware, or a processor configured to execute a program stored in a memory.

When the processing circuit is dedicated hardware, the processing circuit corresponds to, for example, a single circuit, a composite circuit, a programmed processor, a parallel-programmed processor, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or a combination thereof. The functions of the respective units including the inverter control unit40, the maximum current adjustment unit51, the allowable torque calculation unit52, the upper limit number-of-rotation calculation unit53, the number-of-rotation adjustment unit54, and the torque command adjustment unit55may be implemented by individual processing circuits, or the functions of the respective units may together be implemented by a processing circuit.

Meanwhile, when the processing circuit is a processor, the function of each of the inverter control unit40, the maximum current adjustment unit51, the allowable torque calculation unit52, the upper limit number-of-rotation calculation unit53, the number-of-rotation adjustment unit54, and the torque command adjustment unit55is implemented by software, firmware, or a combination of software and firmware. The software and the firmware are coded as programs and stored in a memory. The processor reads out and executes the program stored in the memory, to thereby implement the function of each of the units. That is, the control device includes a memory for storing program, and when the programs are executed by a processing circuit, there are consequently executed an inverter control step, a maximum current adjustment step, an allowable torque calculation step, an upper limit number-of-rotation calculation step, a number-of-rotation adjustment step, and a torque command adjustment step.

It is also understood that those programs cause a computer to execute procedures and methods for the respective units. In this case, the memory corresponds to, for example, a random access memory (RAM), a read only memory (ROM), a flash memory, an erasable programmable read only memory (EPROM), an electrically erasable and programmable read only memory (EEPROM), or other such non-volatile or volatile semiconductor memory. The memory also corresponds to, for example, a magnetic disk, a flexible disk, an optical disc, a compact disc, a MiniDisk, or a DVD.

Some of the functions of the respective units described above may be implemented by dedicated hardware, and other thereof may be implemented by software or firmware.

In this manner, the processing circuit can implement the function of each of the units described above by hardware, software, firmware, or a combination thereof.

INDUSTRIAL APPLICABILITY

The present invention is applicable in all industries that manufacture a control device for an AC rotating electric machine.

REFERENCE SIGNS LIST