JP6099724B1 - Electric motor control device - Google Patents

Abstract

An electric motor control device capable of protecting the temperature of an electric motor power converter is obtained. A motor for controlling a motor by outputting a PWM signal to a motor power converter, and a temperature detector for detecting the temperature of the motor power converter, and when the output of the temperature detector is a predetermined value or more. For generating a PWM signal, a temperature protection determination unit 31 that outputs a temperature protection operation command, a torque limit determination unit 33 that determines whether or not to perform torque limitation for temperature protection in response to a torque request from a vehicle, and A carrier frequency limit execution determination unit 35 for determining whether or not to perform carrier limitation for temperature protection with respect to the carrier frequency to be used is provided. When the temperature protection determination unit outputs a temperature protection operation command, torque limit determination is performed. Depending on the temperature of the motor power converter and the state quantity of the vehicle, whether the torque is limited by the output from the unit or the carrier is limited by the output from the carrier frequency limit execution determination unit It was to be constant. [Selection] Figure 1

Description

  The present invention relates to an electric motor control device that enables protection of an electric motor (hereinafter referred to as a motor as appropriate), an electric motor control device, and an electric motor power converter based on a state quantity of a vehicle.

  In recent years, electric vehicles, hybrid vehicles, fuel cell vehicles, and the like have attracted a great deal of attention as environmentally friendly vehicles. In such a vehicle, the output of the motor is part or all of the driving force, and the motor is generally controlled by an electric motor control device. In the case of driving an AC motor with a DC power supply, an electric motor power conversion device that converts power output into AC is necessary. In an electric motor power conversion device, power conversion is performed by switching a switching element with high frequency and high power. Since such switching may cause the switching element of the electric motor power conversion device to generate heat and cause destruction, it is necessary to consider temperature protection of the switching element when controlling the electric motor power conversion device.

Therefore, there are techniques for limiting the amount of torque that can be output or reducing the carrier frequency that is the basis of the switching frequency when the temperature of the electric motor power converter rises.
In Patent Document 1, when the temperature of the switching element rises, torque limitation is not performed immediately, but control is first performed by switching from a high frequency carrier frequency to a low frequency carrier frequency, and when the temperature rises, the torque limit value is finally reached. Control is performed with a small value. If the torque rises immediately when the temperature rises, for example, while climbing up the hill, it stops without climbing the hill, whereas this method does not reduce the torque. It can prevent fever and is effective.

JP-A-9-121595

  As described above, heat generation can be suppressed by limiting the torque generated in the motor and reducing the current flowing through the switching element. However, there is a problem in that the torque that can be output decreases and the torque request from the vehicle cannot be met. On the other hand, if the carrier frequency that is the source of the switching frequency is lowered, heat generation of the switching element can be suppressed without lowering the torque. However, when the carrier frequency is lowered, there is a concern that noise may become a problem or torque pulsation may occur due to degradation of current control response.

  Here, when the motor output is a part or all of the driving force of the vehicle, if torque pulsation occurs in the motor, the vehicle will unintentionally repeat acceleration and deceleration, causing discomfort to the driver and passengers. As well as disturbing safe driving. It is important to respond to the torque demand from the vehicle, but depending on the vehicle situation, the above-mentioned problems cannot be neglected and the occurrence must be prevented. That is, it is necessary to determine whether to limit torque or to limit carrier frequency according to the vehicle situation. However, in the conventional invention, when the temperature protection is required, the carrier frequency is first lowered regardless of the vehicle situation. Therefore, priority is always given to securing the required torque, and the effects of noise and current control response degradation are taken into account. It has not been.

The present invention has been made in order to solve the above-described problems, and compensates for the respective disadvantages by properly using a method for limiting the torque and a method for limiting the carrier frequency according to the state quantity of the vehicle. The motor power converter can be protected from temperature without realizing discomfort due to repeated motor noise and unintentional acceleration / deceleration while realizing torque demand from the vehicle as much as possible. An object of the present invention is to provide an electric motor control device.

The motor control device according to this aspect includes an energization signal generation unit that generates a PWM energization signal for controlling the electric motor, and outputs the electric power to the electric motor power conversion device. A temperature detection unit that detects temperature, a temperature protection determination unit that outputs a temperature protection operation command when the output of the temperature detection unit is greater than or equal to a predetermined value, and a temperature protection for a torque request from the vehicle A torque limit determination unit that determines whether or not to perform the torque limit, and a carrier frequency limit that determines whether or not to limit the carrier for temperature protection with respect to the carrier frequency used to generate the PWM energization signal An execution determination unit is provided, and when the temperature protection determination unit outputs an operation command for temperature protection, torque is limited by the output from the torque limit determination unit or the carrier frequency limit execution determination unit Whether to carrier confinement in force, and determines in accordance with the temperature and the state of the vehicle of the motor power converter, a torque limit determining section, and a torque limit value calculated based on the temperature detection value of the motor power converter The torque request value of the vehicle is compared, and when the torque request value exceeds the positive side or the negative side of the torque limit value, a torque limit operation command is output .

  The present invention uses two types, a method for limiting torque and a method for limiting carrier frequency for the purpose of temperature protection when the temperature of the switching element of the electric motor power conversion device rises. By properly using them according to the above, making use of the advantages and realizing the torque request from the vehicle as much as possible, without giving the driver discomfort such as motor noise and repeated unintentional acceleration / deceleration of the vehicle, An electric motor control device that can protect the temperature of the electric motor power conversion device can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a whole block diagram which shows schematic structure of the electric motor control apparatus which concerns on Embodiment 1 of this invention with the electric motor which is load. It is a figure which shows the effect of the electric motor control apparatus which concerns on Embodiment 1 of this invention compared with a prior art invention in a torque request value, a torque command value, and a torque actual value. It is a whole block diagram which shows schematic structure of the electric motor control apparatus which concerns on Embodiment 2 of this invention with the electric motor which is load.

Embodiment 1 FIG.
Hereinafter, an electric motor control apparatus according to Embodiment 1 of the present invention will be described with reference to FIGS. 1 and 2.
FIG. 1 is a schematic configuration diagram of an electric motor control device according to Embodiment 1 of the present invention. In FIG. 1, the electric motor control device 1 generates a PWM (pulse width modulation) energization signal for controlling the electric motor 2. Based on the output from the motor control device 1, the motor power conversion device 3 outputs an AC voltage to control the motor 2.

  The electric motor 2 is a three-phase synchronous motor, and has a stator (armature winding) and a rotor (field winding). The connection of the armature winding is assumed to be a three-phase Y connection. In addition, as a rotor field method, there are mainly a permanent magnet field method using a permanent magnet, a winding field method, and a combination method of permanent magnets and windings. Here, a permanent magnet field method is used. I will use it. Further, a motor position sensor 21, a DC voltage sensor 22, a current sensor 23, and a temperature sensor 24 are provided to detect the state quantity of the electric motor 2.

Moreover, the electric motor control device 1 includes a voltage command generation unit 12, a temperature protection unit 13, an energization signal generation unit 14, and a current detection unit 15 and a rotational position detection unit as detection units that perform detection based on each sensor output. 16, an electrical angular frequency calculation unit 17, a DC voltage detection unit 18, and a temperature detection unit 19.
Based on the output from the current sensor 23, the current detection unit 15 detects and outputs a three-phase current flowing through the armature winding of the electric motor 2. The rotational position detector 16 detects and outputs the rotational position of the electric motor 2 based on the rotor position signal from the motor position sensor 21, and the electrical angular frequency calculator 17 based on the output of the rotational position detector 16 The electric angular frequency of the electric motor 2 is calculated and output. Since the electrical angular frequency is proportional to the reciprocal of the rotational speed of the electric motor 2 and the rotational speed of the electric motor is proportional to the engine rotational speed (vehicle speed) of the vehicle, the electrical angular frequency calculating unit 17 includes the electric motor rotational speed detecting unit and the vehicle rotational speed. It also operates as a speed detector. The DC voltage detection unit 18 detects and outputs the DC voltage of the battery supplied to the electric motor power conversion device 3 based on the output from the DC voltage sensor 22. The temperature detector 19 detects and outputs a temperature value based on the temperature signal of the switching element of the electric motor power converter 3 that is the output of the temperature sensor 24.

  The voltage command generation unit 12 generates a three-phase AC voltage command value corresponding to the torque command value that is the output of the temperature protection unit 13. The voltage command value may be generated in any way, but here, a procedure for generating it using current control will be described. First, based on at least one of the output of the electrical angular frequency calculation unit 17 and the output of the DC voltage detection unit 18 and the torque command value, a current command value on the dq axis to be passed through the armature winding of the motor 2 is generated. Next, the current detection value on the dq axis is obtained from the output of the current detection unit 15 that detects the current of the three-phase alternating current actually flowing in the armature winding by using a general three-phase-dq conversion. PI control is performed based on the deviation between the current command value on the dq axis and the detected current value on the dq axis to generate a voltage command on the dq axis. From the output of the rotational position detector 16 and the voltage command value on the dq axis, a three-phase AC voltage command value is obtained using general dq-3 phase conversion.

  The energization signal generator 14 generates and outputs a PWM energization signal (PWM signal) from the detected DC voltage detected by the DC voltage detector 18 and the three-phase AC voltage command value calculated by the voltage command generator 12. To do. Specifically, 0.5 is added to the voltage command divided by the DC voltage to generate a DuTy command in which the value range is normalized to 0 to 1 (the value of the DuTy command may be expressed as a percentage). Then, a PWM energization signal (PWM signal) is generated and output by comparing the DuTy command with a carrier wave (a triangular wave whose value range is 0 to 1). The frequency of the carrier wave is set according to the output of the carrier frequency calculation unit 36 described later.

  The electric motor power converter 3 outputs an AC voltage based on the PWM energization signal that is the output of the energization signal generator 14 and energizes the armature winding of the motor 2. The electric motor power conversion device 3 has an upper arm and a lower arm connected in series for each of the U, V, and W phases. Each arm has a configuration in which switching elements such as IGBTs (Insulated Gate Bipolar Transistors) and GCTs (Gate Commutated Turn-off Thyristors) and free-wheeling diodes are connected in antiparallel. Hereinafter, turning on a switching element of a certain arm may be simply expressed as “arm is turned on” and turning off is simply expressed as “arm is turned off”.

  When the switching element of the upper arm is turned on by the PWM energization signal, the output terminal voltage becomes Hi (approximately DC voltage level), and when the switching element of the lower arm is turned on, the output terminal voltage becomes Low (approximately ground level). . The output terminal voltage is a voltage at a connection point between the upper arm and the lower arm, and is equal to a voltage connected to a line of each phase (U, V, W) of the armature winding. Note that if the switching elements of the upper arm and the lower arm are simultaneously turned on, the DC voltage is short-circuited, so that the two switching elements are not simultaneously turned on. In this way, the DC voltage is converted into an AC voltage.

  Here, switching of the switching element of the electric motor power conversion device 3 is performed with high frequency and high power. Since such switching generates heat in the switching element, it is necessary to consider temperature protection of the switching element. In order to protect the temperature of the switching element, it is effective to suppress heat generation by limiting the torque of the electric motor 2 and reducing the current flowing through the switching element. However, there is a case where the torque is reduced and the torque request from the vehicle cannot be met. On the other hand, if the carrier frequency that is the source of the switching frequency is lowered, heat generation of the switching element can be suppressed without lowering the torque.

However, in order to reduce noise and increase the response of current control, it is better to increase the carrier frequency and increase the switching frequency of the switching element.
In the present invention, when the temperature of the switching element of the electric motor power converter 3 rises, two methods, a method for limiting the torque and a method for limiting the carrier frequency for the purpose of temperature protection, are used. Use them according to your needs. By doing so, the respective drawbacks are compensated and the advantages are utilized, and the driver is given unpleasant feeling due to the repeated noise and the unintended acceleration / deceleration of the vehicle while realizing the torque request from the vehicle as much as possible. In addition, the temperature protection of the electric motor power conversion device 3 can be performed.

The temperature protection unit 13 includes a temperature protection determination unit 31, a torque limit value calculation unit 32, a torque limit determination unit 33, a torque limit unit 34, a carrier frequency limit execution determination unit 35, and a carrier frequency calculation unit 36. Have.
The temperature protection determination unit 31 determines that temperature protection is necessary when the temperature detection value of the switching element, which is the output of the temperature detection unit 19, is equal to or greater than a predetermined value, and outputs a temperature protection operation command.

  The torque limit value calculation unit 32 calculates a torque limit value based on the temperature detection value of the switching element when the temperature protection determination unit 31 outputs a temperature protection operation command. The torque limit value includes a temperature-torque limit value conversion map, and may be obtained by referring to this map, or may be obtained by calculation using an equation for deriving the torque limit value from the temperature value. Here, since the torque request has a positive / negative value, the torque limit value similarly has a positive / negative value.

The torque limit determination unit 33 compares the torque request value output from the host control control unit (ECU) 25 of the vehicle with the torque limit value from the torque limit value calculation unit 32, and the torque request value is on the positive side of the torque limit value. Or, when exceeding the negative side, a torque limit operation command is output.
When the torque limit determination unit 33 outputs a torque limit operation command, the torque limit unit 34 limits the torque requested value output from the host control control unit (ECU) 25 of the vehicle and sets the torque command value. Output.
Thus, when the temperature protection determination unit 31 outputs a temperature protection operation command, the torque limit determination unit 33 determines whether to perform torque limitation for temperature protection in response to a torque request from the vehicle. Determine.

  The carrier frequency limit execution determination unit 35 includes a determination unit 35-a based on an electrical angular frequency, a determination unit 35-b based on a torque command rate, a determination unit 35-c based on a DC voltage, and a carrier limit determination output unit 35-d. It consists of The carrier frequency limit execution determination unit 35 limits the carrier frequency for the purpose of temperature protection with respect to the carrier frequency used for generating the PWM energization signal when the temperature protection determination unit 31 outputs the temperature protection operation command. It is determined whether or not to perform.

The electrical angular frequency determination unit 35-a outputs a carrier limit permission signal based on the electrical angular frequency when the electrical angular frequency output by the electrical angular frequency calculation unit 17 is equal to or greater than a predetermined value. Here, for the predetermined value of the electrical angular frequency, the vehicle speed at which the traveling sound of the traveling vehicle masks the electromagnetic sound of the electric motor 2 is investigated in advance, and the electrical angular frequency obtained from the vehicle speed is set.
That is, when the carrier frequency used for PWM control is lowered, the electromagnetic noise of the motor 2 increases. However, when the electrical angular frequency is high, that is, when the vehicle is traveling at a high speed, the surrounding noise is large and the motor 2 It is determined that the electromagnetic sound is not a problem as noise, and the restriction of the carrier frequency is permitted.

The torque command rate determination unit 35-b has torque command rate calculation means for calculating a torque command rate that is a change rate of the torque command from a torque command value that is an output of the torque limiter 34, and the torque command rate is predetermined. In the case of the range, a carrier limit permission signal based on the torque command rate is output. The determination unit 35-b based on the torque command rate is provided with torque request rate calculation means for calculating the rate of change of the torque request from the vehicle. When the torque request rate is within a predetermined range, the carrier limit permission signal based on the torque request rate. May be output.
Here, the significance of determining the operation of limiting the carrier frequency based on the torque command rate will be described. When the carrier frequency used for PWM control is lowered, the response of current control deteriorates, torque pulsation occurs in the electric motor 2 and the vehicle repeatedly accelerates and decelerates, which not only makes the driver and passengers uncomfortable. May interfere with safe driving.

  In particular, in a state where there is a constant torque request such as when the driver is maintaining the accelerator position, the human frequency is not easily limited because the person can easily detect a change in the driving force of the vehicle due to torque pulsation. On the other hand, in a state where the torque demand from the vehicle changes greatly as when the accelerator is depressed all at once, and the actual torque change is also large, humans are difficult to detect changes in the driving force of the vehicle due to torque pulsation. Make restrictions. However, if the torque change is too large, the torque pulsation becomes too large. In this case, the carrier frequency is not limited.

  The determination unit 35-c based on DC voltage outputs a carrier restriction permission signal based on DC voltage when the output of the DC voltage detection unit 18 that detects DC voltage supplied to the motor power converter 3 is equal to or less than a predetermined value. If the carrier frequency used for PWM control is lowered, the responsiveness of the current control deteriorates and torque pulsation occurs in the electric motor 2. However, when the DC voltage is low, the magnitude of the generated torque pulsation is small and acceptable. The carrier frequency used for PWM control is limited.

  When the determination unit 35-a based on the electrical angular frequency outputs the carrier limit permission based on the electrical angular frequency, the determination unit 35-b based on the torque command rate permits the carrier limit permission based on the torque command rate. When output, the carrier limiting operation command is output when any one of the determination units 35-c based on DC voltage outputs the carrier limitation permission based on the DC voltage. When the carrier limit determination output unit 35-d outputs a carrier limit operation command, the carrier frequency calculation unit 36 sets the carrier frequency used for PWM control to a predetermined value set lower than normal.

As described above, in the present invention, when the temperature protection determination unit 31 outputs a temperature protection operation command, whether or not to activate a torque limit for the purpose of temperature protection in response to a torque request from the vehicle, Whether carrier restriction for temperature protection is activated or not is determined according to the temperature of the motor power converter 3 and the state quantity of the vehicle with respect to the carrier frequency used for PWM control of the motor control device. Yes.
Here, the state quantity of the vehicle is, as described above, a torque request value from the vehicle, a torque command value that is a value that limits the torque request from the vehicle, a vehicle speed (the number of revolutions of the electric motor 2). ), Which is at least one of the voltage values supplied to the electric motor power conversion device 3.
In the case where the carrier limit determination output unit 35-d does not output the carrier limit operation command even though the temperature protection determination unit 31 outputs the temperature protection operation command, the torque limit value calculation unit 32 determines the torque limit. To compensate for the lack of temperature protection due to the carrier frequency limiting process not working.

FIG. 2 is a diagram showing the effect of the electric motor control device of the present invention in comparison with the conventional invention in terms of torque request value, torque command value, and actual torque value. In FIG. 2, the horizontal axis indicates time, and the vertical axis indicates a torque request value, a torque command value, and an actual torque value.
First, the case of no temperature protection during the torque increase command and the torque decrease command will be described with reference to 1-a) and 1-b) of FIG. During the torque increase command, as shown in 1-a) of FIG. 2, the torque is increased from 0 [Nm] to Tmax [Nm] from 0 [s] to t3 [s], and after t3 [s]. It can be seen that the torque actual value follows and converges with respect to the torque request for maintaining this, although there is a delay of t4-t3 [s] in the arrival time to Tmax [Nm].

  Similarly, during the torque reduction command, the torque is maintained at Tmax [Nm] from 0 [s] to t7 [s], and from t7 [s] to t10 [s] as shown in 1-b) of FIG. ], The actual torque value has a delay of t11-t10 [s] in the arrival time to 0 [Nm] for the torque request to decrease from Tmax [Nm] to 0 [Nm]. It can be seen that it follows and converges. In the case of no temperature protection, the torque request value and the torque command value are equal because no torque limitation is applied.

  Next, the case where temperature protection is applied in the conventional invention will be described with reference to 2-a) and 2-b) of FIG. In the conventional invention, the temperature protection is performed in two stages, the temperature protection-step S1 lowers the carrier frequency, and the temperature further increases, the temperature protection-step S2 not only lowers the carrier frequency but also limits the torque. A value obtained by applying a torque limit to the torque request value in step S2 is defined as a torque command value. In the case of no temperature protection and temperature protection-step S1, the torque request value is equal to the torque command value because no torque limitation is applied.

During the torque increase command, as shown in 2-a) of FIG. 2, the torque is increased from 0 [Nm] to Tmax [Nm] from 0 [s] to t3 [s], and after t3 [s]. A torque request is received to maintain this, but temperature protection-step S1 is applied from t1 [s] to t5 [s] for temperature rise, and temperature protection-step S2 is applied after t5 [s]. And
Similarly, during the torque reduction command, the torque is maintained at Tmax [Nm] from 0 [s] to t7 [s] and from t7 [s] to t10 [s] as shown in FIG. In the meantime, a torque request for decreasing from Tmax [Nm] to 0 [Nm] is received, but temperature protection is performed during the period from 0 [s] to t6 [s] due to the temperature rise-step S2 and t6 [s. ] To t9 [s] is subjected to temperature protection-step S1, and after t9 [s], the temperature protection is released. Although the actual torque value follows the torque command value that limits the torque request, it can be seen that pulsation occurs in the torque because the responsiveness of the current control is degraded by lowering the carrier frequency.

A case where temperature protection is applied in the present invention will be described with reference to 3-a) and 3-b) of FIG. In the present invention, after the temperature protection is determined, a torque limit determination and a carrier limit determination are performed according to the vehicle state quantity. In the first embodiment, the torque limit value is calculated by referring to the map.
During the torque increase command, the torque is increased from 0 [Nm] to Tmax [Nm] from 0 [s] to t3 [s], as shown in 3-a) of FIG. 2, and after t3 [s] A torque request is received to maintain this. For temperature rise, temperature protection is applied after t1 [s]. In response to the temperature protection operation command, the torque limit value is calculated. However, since the required torque does not exceed the torque limit value, the torque limit is not applied from t1 [s] to t2 [s]. On the other hand, the carrier frequency is limited in this section because the torque command rate is within a predetermined range. Since the required torque exceeds the torque limit value at t2 [s], torque limit is applied. On the other hand, since the torque command rate is out of the predetermined range, the carrier frequency is not limited.

  During the torque reduction command, as shown in FIG. 2B, the torque is maintained at Tmax [Nm] from 0 [s] to t7 [s], and from t7 [s] to t10 [s]. Torque request to decrease from Tmax [Nm] to 0 [Nm]. Temperature protection is applied from 0 [s] to t9 [s] due to temperature rise. In response to the temperature protection operation command, the torque limit value is calculated. From 0 [s] to t8 [s], the torque request value exceeds the torque limit value, and thus the torque limit is applied. On the other hand, since the torque command rate is outside the predetermined range in this section, the carrier frequency is not limited. Since the torque request falls below the torque limit value at t8 [s], the torque limit is not applied. On the other hand, the carrier frequency is limited because the torque command rate is in a predetermined range. After t9 [s], the temperature protection is canceled, so neither torque limitation nor carrier frequency limitation is performed. Compared to the conventional invention, there are many sections where the torque demand is limited, but the carrier frequency is lowered according to the torque command rate, so the torque pulsation due to the responsiveness deterioration of the current control gives driver and passenger discomfort. Therefore, it is possible to protect the temperature of the switching element.

In the first embodiment, the temperature protection determination unit 31 determines that temperature protection is necessary when the temperature detection value of the switching element, which is the output of the temperature detection unit 19, is equal to or greater than a predetermined value, and outputs a temperature protection operation command. However, it is also possible to attach a temperature sensor to the electric motor 2 and output a temperature protection operation command when the temperature value of the electric motor 2 is a predetermined value or more. By doing so, not only the switching element but also the temperature protection of the electric motor 2 can be implemented.
For temperature protection of the electric motor 2, it is effective to reduce the torque generated in the electric motor 2 and reduce the current flowing in the armature winding to perform the torque limiting process, but to lower the switching frequency of the switching element, The carrier frequency limiting process is not expected to be effective. Not only can temperature protection not be expected, but it is also difficult to cause noise and current control response degradation due to carrier frequency limitations. Therefore, when the temperature rise of the switching element is not observed and only the temperature rise of the electric motor 2 occurs, the carrier frequency limiting process is not performed and the torque limiting process is performed.

  In the first embodiment, when the carrier limit determination output unit 35-d outputs a carrier limit operation command, the carrier frequency calculation unit 36 does not limit the set value of the carrier frequency set lower than usual. According to the evaluation, the frequency of the electromagnetic sound generated in the electric motor 2 according to the change in the carrier frequency is measured, and the value of the carrier frequency used for the carrier restriction is not in the human audible range where the noise of the electric motor 2 is a problem. It may be set to any value.

In the first embodiment, the armature winding of the electric motor 2 to be controlled by the electric motor control device 1 is assumed to be a three-phase Y connection. However, other connections are possible as long as the detection current or the line current can be detected. Alternatively, for example, a three-phase Δ connection may be used.
As described above, according to the invention of the first embodiment, when the temperature protection determination unit outputs a temperature protection operation command, the torque limit determination unit determines whether the temperature of the electric motor power conversion device and the state quantity of the vehicle are Therefore, it is determined whether to limit the torque with the output of the carrier or to limit the carrier with the output from the carrier frequency limit execution determination unit. Thus, it is possible to protect the temperature of the electric motor power converter without giving the driver an unpleasant feeling of repeated acceleration / deceleration.

Embodiment 2. FIG.
Next, an electric motor control apparatus according to Embodiment 2 of the present invention will be described with reference to FIG.
As described above, when the switching element of the electric motor power conversion device 3 is switched, the switching element generates heat. Therefore, in order to prevent heat generation, the carrier frequency that is the source of the switching frequency may be lowered. As an extreme theory, if switching of the switching element is stopped, heat generation of the switching element due to switching can be eliminated.
In the second embodiment, the temperature protection determination unit 31 outputs a temperature protection operation command, and when the torque of the electric motor 2 is 0 Nm, the switching is promptly stopped so that the temperature of the switching element is protected. It is a thing.
Further, by stopping the switching while estimating the torque generated by the electric motor, a sudden change in torque that causes a torque shock is prevented.

FIG. 3 shows a schematic configuration diagram of an electric motor control apparatus according to Embodiment 2 of the present invention. In FIG. 3, the electric motor control apparatus 1 generates a PWM energization signal for controlling the electric motor 2 to generate electric power conversion apparatus 3. The motor power conversion device 3 outputs an AC voltage based on the output from the motor control device 1 to drive and control the motor 2.
As the field system of the rotor of the electric motor 2, the permanent magnet field system using a permanent magnet is used in the first embodiment, but the winding field system is used in the second embodiment.

In FIG. 3, the voltage command generator 12 generates a three-phase AC voltage command value according to the torque command value output from the temperature protector 13, and outputs a three-phase voltage command generator 12-a. And a field voltage command generation unit 12-b that generates and outputs a field voltage command value according to a torque command value that is an output of the unit 13, and controls a current flowing through the field winding. Yes.
The field voltage command generation unit 12-b may generate the field voltage command value in any way, but here, a procedure of generation using current control will be described. First, a field current command value to be passed through the field winding of the electric motor 2 is generated based on at least one of the output of the electrical angular frequency calculation unit 17 and the output of the DC voltage detection unit 18 and the torque command value. Next, PI control is performed based on the deviation between the field current command value and the output of the field current detector 15-b to generate a field voltage command.

  In the temperature protection unit 13, the carrier frequency calculation unit 36 includes a three-phase carrier frequency calculation unit 36-a and a field carrier frequency calculation unit 36-b. The three-phase carrier frequency calculation unit 36-a calculates and outputs a value lower than the normal three-phase carrier frequency when the carrier frequency limit execution determination unit 35 outputs a carrier limit operation command. The field carrier frequency calculation unit 36-b calculates and outputs a value lower than the normal field carrier frequency when the carrier frequency limit execution determination unit 35 outputs a carrier limit operation command.

The energization signal generation unit 14 includes a three-phase energization signal generation unit 14-a and a field energization signal generation unit 14-b.
The three-phase energization signal generation unit 14-a generates an energization signal (PWM signal) from the DC voltage detection value detected by the DC voltage detection unit 18 and the three-phase AC voltage command value calculated by the three-phase voltage command generation unit 12-a. ) Is generated and output. Specifically, 0.5 is added to the value obtained by dividing the three-phase voltage command value by the DC voltage value to generate a DuTy command in which the value range is normalized to 0 to 1, and the three-phase carrier frequency calculation unit A three-phase energization signal (PWM signal) is generated and output by comparing the carrier wave (triangular wave whose value range is 0 to 1) generated according to the output of 36-a and the DuTy command.

  Further, the field energization signal generation unit 14-b generates an energization signal (PWM) from the DC voltage detection value detected by the DC voltage detection unit 18 and the field voltage command value calculated by the field voltage command generation unit 12-b. Signal) is generated and output. Specifically, 0.5 is added to the value obtained by dividing the field voltage command value by the DC voltage value to generate a DuTy command in which the value range is normalized to 0 to 1, and the field carrier frequency calculation unit A field energization signal (PWM signal) is generated and output by comparing the carrier wave (triangular wave whose value range is 0 to 1) generated according to the output of 36-b and the DuTy command.

  The current detection unit 15 is configured by dividing the current sensor 23 into a three-phase current sensor 23-a and a field current sensor 23-b, and detects a three-phase current flowing in the armature winding of the motor 2 respectively. The current detection unit 15-a and a field current detection unit 15-b that detects a field current flowing in the field winding of the electric motor 2 are configured.

The motor torque estimation unit 37 calculates and outputs an estimated torque value generated in the motor 2 according to the output of the current detection unit 15 and the output of the DC voltage detection unit 18. In the drive stop determination unit 38, the temperature protection determination unit 31 outputs a temperature protection operation command, the torque command that is the output of the torque limiting unit 34 is 0 Nm, and the output magnitude (absolute value) of the motor torque estimation unit 37 Is less than a predetermined value, a drive stop command is output to the energization signal generator 14.
Other configurations are the same as those in FIG. 1 of the first embodiment, and the same or corresponding parts are denoted by the same reference numerals and description thereof is omitted.

  When the drive stop determination unit 38 outputs a drive stop command, the drive stop determination unit 38 fixes the three-phase energization signal (PWM signal) output from the three-phase energization signal generation unit 14-a to a predetermined value, and Stops switching of the three-phase switching element. Similarly, when the drive stop determination unit 38 outputs a drive stop command, the drive stop determination unit 38 fixes the field energization signal output from the field energization signal generation unit 14-b to a predetermined value, so that the field of the motor power conversion device is fixed. The switching of the magnetic switching element is stopped.

Even if the torque command is set to 0 Nm, the torque generated in the electric motor 2 does not always become 0 Nm, and when the switching of the switching element of the electric motor power converter 3 is stopped despite the torque being generated, the torque May cause a torque shock or an overcurrent. Therefore, after confirming the disappearance of the torque because the magnitude (absolute value) of the output of the motor torque estimation unit 37 is equal to or less than a predetermined value, a drive stop command is output to the energization signal generation unit 14. By stopping the switching of the electric motor power converter 3, it is possible to prevent occurrence of torque shock or overcurrent abnormality due to the switching stop.
Note that the predetermined value of the estimated torque value for outputting the drive stop command is adjusted to a value at which the driver does not feel a torque shock when mounted on the actual vehicle.

In the second embodiment, the motor torque estimation unit 37 obtains an estimated torque value generated in the motor 2 according to the output of the current detection unit 15 and the output of the DC voltage detection unit 18, and the estimated torque value is equal to or less than a predetermined value. Therefore, the disappearance of the torque actually generated in the electric motor 2 was confirmed.
However, from the output of the three-phase current detector 15-a that actually detects the three-phase AC current flowing in the armature winding of the electric motor 2, the general three-phase-dq conversion is used on the dq axis. The current detection value is obtained, and the current detection value on the dq axis is equal to or less than a predetermined value, and the field current detection unit 15-b that detects the current of the field actually flowing in the field winding of the electric motor 2 The disappearance of the torque actually generated in the electric motor 2 may be confirmed by the output being equal to or less than a predetermined value. By doing in this way, generation | occurrence | production of the torque shock and overcurrent abnormality by switching stop can be prevented with a simple structure rather than providing the motor torque estimation part 37. FIG.

  In the first and second embodiments, the temperature sensor 24 is attached to the motor 2 and the motor power conversion device 3 and the temperature value is acquired by the temperature detection unit 19. However, the output of the current detection unit 15 and the DC voltage are used. It is good also as a structure which acquires a temperature value by estimation from the output of the detection part 18. FIG. By setting it as such a structure, a temperature value can be acquired with a simple structure, without attaching a temperature sensor newly.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the embodiments, and various design changes can be made. Within the scope of the present invention, each embodiment These embodiments can be freely combined, and each embodiment can be modified or omitted as appropriate.

1: motor controller, 2: motor (motor), 3: motor power converter, 12: voltage command generator, 12-a: three-phase voltage command generator, 12-b: field voltage command generator, 13 : Temperature protection unit, 14: energization signal generation unit, 14-a: three-phase energization signal generation unit, 14-b: field energization signal generation unit, 15: current detection unit, 15-a: three-phase current detection unit 15 -B: field current detection unit, 16: rotational position detection unit, 17: electrical angular frequency calculation unit, 18: DC voltage detection unit, 19: temperature detection unit, 21: motor position sensor, 22: DC voltage sensor, 23 : Current sensor, 23-a: three-phase current sensor, 23-b: field current sensor, 24: temperature sensor, 25: host control control unit (ECU), 31: temperature protection determination unit, 32: torque limit value calculation Unit, 33: torque limit execution determination unit, 34: Torque limiter, 35: carrier frequency limit execution determination unit, 35-a: determination unit based on electrical angular frequency (second determination unit), 35-b: determination unit based on torque command rate (first determination unit), 35 -C: DC voltage determination unit (third determination unit), 36: carrier frequency calculation unit, 36-a: three-phase carrier frequency calculation unit, 36-b: field carrier frequency calculation unit, 37: torque estimation unit 38: Drive stop determination unit

Claims (10)

An electric motor control device that includes an energization signal generation unit that generates an energization signal of PWM for controlling the electric motor, and outputs the electric power to the electric motor power conversion device,
In response to a torque request from a vehicle, a temperature detection unit that detects the temperature of the electric motor power converter, a temperature protection determination unit that outputs an operation command for temperature protection when the output of the temperature detection unit is equal to or greater than a predetermined value, A torque limit determination unit for determining whether or not to limit torque for the purpose of temperature protection, and whether to limit the carrier for the purpose of temperature protection with respect to the carrier frequency used for generating the PWM energization signal. A carrier frequency limit execution determination unit for determining whether or not
When the temperature protection determination unit outputs an operation command for temperature protection, whether to limit torque with the output from the torque limit determination unit, or to perform carrier limitation with the output from the carrier frequency limit execution determination unit, The torque limit determination unit determines the torque limit value calculated based on the temperature detection value of the motor power converter, and the torque request of the vehicle , according to the temperature of the motor power converter and the state quantity of the vehicle. A motor control device that compares values and outputs a torque limit operation command when the torque request value exceeds a positive side or a negative side of the torque limit value .   The state quantity of the vehicle includes a torque request value from the vehicle, a torque command value that is a value obtained by limiting the torque request from the vehicle, a speed of the vehicle, and a voltage supplied to the electric motor power converter. The motor control device according to claim 1, wherein the motor control device is at least one of the values. The carrier frequency limit execution determination unit is a torque request rate calculation means for calculating a rate of change in torque request from the vehicle, or a torque command rate of change that is a value obtained by limiting the torque request from the vehicle. A torque command rate calculating means for calculating, and a first determination unit for determining whether to perform carrier restriction based on a torque change rate, wherein the temperature protection determination unit outputs a temperature protection operation command; If the output of the torque demand rate calculation means or an output of the torque command rate calculation means if a predetermined range, according to claim 1 or claim 2, characterized in that to lower the carrier frequency used for PWM control Electric motor control device. The carrier frequency limitation execution determination unit includes a second determination unit that determines whether to perform carrier limitation based on the speed of the vehicle, and when the temperature protection determination unit outputs an operation command for temperature protection. 4. The motor control device according to claim 1 , wherein if the speed of the vehicle is equal to or higher than a predetermined value, the carrier frequency used for PWM control is lowered. The carrier frequency limit execution determination unit includes a third determination unit that determines whether or not to perform carrier limitation based on a DC voltage supplied to the electric motor power converter, and the temperature protection determination unit operates temperature protection. 5. The motor control device according to claim 1 , wherein when the command is output, if the DC voltage is equal to or less than a predetermined value, the carrier frequency used for PWM control is lowered. The motor control apparatus according to any one of claims 4 to 5 , wherein the carrier frequency range does not set a frequency range in which electromagnetic sounds in a human audible range are generated. An electric motor temperature detection unit for detecting the temperature of the electric motor is provided, and the temperature protection determination unit outputs an operation command for temperature protection when the temperature of the electric motor power converter or the temperature of the electric motor is equal to or higher than a predetermined value. The motor control device according to any one of claims 1 to 6 . When the temperature of the motor power converter is not more than a predetermined value and the temperature protection determination unit outputs a temperature protection operation command when the temperature of the motor is not less than a predetermined value, the carrier frequency for the purpose of temperature protection is The motor control device according to claim 7 , wherein torque limitation is performed for a torque request from the vehicle without limitation. When the temperature protection determination unit outputs an operation command for temperature protection and the torque command to the motor or a torque command that is a limit value for the torque request to the motor is 0 Nm, the motor power The motor control device according to any one of claims 1 to 8 , wherein switching of the switching element of the conversion device is stopped. A torque estimation unit for estimating torque generated in the motor, wherein the temperature protection determination unit outputs a temperature protection operation command, and limits the torque request to the motor or the torque request to the motor; The switching of the switching element of the electric motor power converter is stopped when the torque command as a value is 0 Nm and the absolute value of the output of the torque estimation unit is equal to or less than a predetermined value. The motor control device according to any one of claims 1 to 8 .

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