JP2022007383A - Cable temperature estimating device - Google Patents

Abstract

To provide a cable temperature estimating device in which a following property of an estimated cable temperature to an actual cable temperature can be improved.SOLUTION: An AC cable is set such that the degree of change in a cable temperature is smaller than the degree of change in a coil temperature. A control device includes an estimated cable temperature calculating unit that calculates an estimated cable temperature by performing a moderating process at a prescribed moderating degree with respect to a coil temperature. The estimated cable temperature calculating unit changes the degree of change in the estimated cable temperature in accordance with the degree of change in the coil temperature. The estimated cable temperature calculating unit uses a first moderating degree as a moderating degree in the moderating process when the coil temperature is increasing (step S103), and uses a second moderating degree as a moderating degree in the moderating process when the coil temperature is decreasing (step S104). Then, the second moderating degree is smaller than the first moderating degree.SELECTED DRAWING: Figure 3

Description

The present invention relates to a cable temperature estimation device.

Vehicles such as hybrid vehicles are equipped with a motor as a power source for traveling. In a vehicle equipped with a motor, a cable for supplying electric power from an inverter to a motor is composed of a lead wire portion such as a core wire and a covering portion made of an insulating member for protecting the conductor wire portion from a short circuit or the like. In such a vehicle, if the cable temperature of the cable rises and exceeds the permissible limit, the insulating function of the cable sheath is lost, so that it is necessary to use the cable within the permissible temperature range. Therefore, in order to use the cable within the allowable temperature range, it is necessary to know the cable temperature.

Conventionally, as a cable temperature estimation device for estimating a cable temperature, the one described in Patent Document 1 is known. Patent Document 1 describes a technique for estimating a cable temperature based on a current applied to a cable or an atmospheric temperature which is an ambient temperature of a place where the cable is arranged. According to the technique described in Patent Document 1, the cable temperature can be obtained without actually measuring the cable temperature with a sensor.

Japanese Unexamined Patent Publication No. 2015-91147

By the way, the rise in cable temperature is generated not only by self-heating generated by the current flowing through the lead wire of the cable, but also by the coil heat generated from the coil being transmitted to the cable by the current flowing through the coil. .. In particular, in a motor having a high coil space factor, since the coil is precisely wound in the slot accommodating the coil, the amount of heat generated from the coil is large, and a part of this coil heat is transferred from the wire of the coil to the cable. Easy to be transmitted to the side.

Therefore, in the conventional technique described in Patent Document 1, the cable temperature is estimated by considering only the current flowing through the cable and the ambient temperature, and the transfer of coil heat to the cable is not considered. , There was a risk that the estimated cable temperature would deviate from the actual cable temperature.

The present invention has been made by paying attention to the above circumstances, and an object of the present invention is to provide a cable temperature estimation device capable of improving the followability of the estimated cable temperature with respect to the actual cable temperature. ..

The present invention is used in a system including a cable, a motor having a coil connected to the cable, and a coil temperature detector for detecting the coil temperature of the coil, and the cable estimates the cable temperature of the cable. In the temperature estimation device, the cable is set so that the degree of change in the cable temperature is smaller than the degree of change in the coil temperature, and is annealed with a predetermined degree of smoothing with respect to the coil temperature. It is characterized by including an estimated cable temperature calculation unit that calculates the estimated cable temperature by performing the above.

As described above, according to the present invention, it is possible to provide a cable temperature estimation device capable of improving the followability of the estimated cable temperature with respect to the actual cable temperature.

FIG. 1 is a plan view of a vehicle equipped with a motor drive system having a cable temperature estimation device according to an embodiment of the present invention. FIG. 2 is a block diagram showing a configuration of a drive system of the vehicle shown in FIG. FIG. 3 is a flowchart showing the operation of the cable temperature estimation device according to the embodiment of the present invention. FIG. 4 is a diagram illustrating an operation of calculating an estimated cable temperature by the cable temperature estimation device according to an embodiment of the present invention. FIG. 5 is a diagram illustrating an estimated cable temperature calculated by the cable temperature estimation device according to the embodiment of the present invention and a comparative example. FIG. 6 is a diagram showing a more preferable estimated cable temperature and a comparative example calculated by the cable temperature estimation device according to the embodiment of the present invention. FIG. 7 is a diagram showing a more preferable estimated cable temperature and a comparative example calculated by the cable temperature estimation device according to the embodiment of the present invention.

The cable temperature estimation device according to an embodiment of the present invention is used in a system including a cable, a motor having a coil connected to the cable, and a coil temperature detecting unit for detecting the coil temperature of the coil. It is a cable temperature estimation device that estimates the cable temperature of the cable, and the cable is set so that the degree of change in the cable temperature is smaller than the degree of change in the coil temperature, and the degree of smoothing is predetermined with respect to the coil temperature. It is characterized by including an estimated cable temperature calculation unit that calculates an estimated cable temperature by performing a smoothing process. Thereby, the cable temperature estimation device according to the embodiment of the present invention can improve the followability of the estimated cable temperature with respect to the actual cable temperature.

Hereinafter, the cable temperature estimation device according to the embodiment of the present invention will be described with reference to the drawings. 1 to 7 are diagrams illustrating a cable temperature estimation device according to an embodiment of the present invention.

In FIG. 1, the vehicle 1 includes an engine 2 and a motor 7 as power sources, and wheels 10L, 10R, 11L, and 11R, and transmits the power of the engine 2 or the motor 7 to the wheels 10L and 10R. Drive by. The vehicle 1 includes a 12V battery 4, a starter 3, a clutch 5, and a gearbox 6. The starter 3 starts the engine 2 with the electric power of the 12V battery 4. The 12V battery 4 is a secondary battery that generates a voltage of 12 volts. The clutch 5 connects or disconnects the power between the engine 2 and the gearbox 6. The gearbox 6 shifts the rotation transmitted from the engine 2 and the motor 7.

The vehicle 1 includes an inverter 8, a high-voltage lithium-ion battery 9, an AC cable 12, and a DC cable 13. The AC cable 12 constitutes the cable in the present invention.

In FIG. 2, the motor 7 is a three-phase AC synchronous motor having a built-in magnet, and has a stator having coils 7U, 7W, and 7V for three phases of U-phase, V-phase, and W-phase, and coils 7U, 7W, and 7V. It is equipped with a rotor that generates a rotational force by a magnetic flux that changes when an electric current flows through it.

The inverter 8 includes three pairs of two transistors connected in series. A diode is electrically connected in antiparallel between the collector and the emitter of each transistor. The inverter 8 generates three-phase alternating current of U phase, V phase, and W phase.

The AC cable 12 electrically connects the inverter 8 and the coils 7U, 7W, and 7V of the motor 7. A three-phase alternating current from the inverter 8 to the motor 7 and a current due to an induced voltage generated when the motor 7 is rotated flow through the AC cable 12.

The DC cable 13 is a cable that electrically connects the inverter 8 and the high voltage lithium ion battery 9.

The high voltage lithium ion battery 9 is a secondary battery that generates a higher voltage than the 12V battery 4. In this embodiment, the high voltage lithium ion battery 9 is composed of a lithium ion battery. The vehicle 1 may include a secondary battery such as a nickel-metal hydride battery instead of the high-voltage lithium-ion battery 9.

The cable current sensor 24 is a sensor that detects the current flowing through the AC cable 12. The coil temperature sensor 22 is provided inside the motor 7 and detects the temperatures of the coils 7U, 7W, and 7V as the coil temperature. The coil temperature sensor 22 includes a temperature detection element such as a thermistor or a thermoelectric pair. The coil temperature sensor 22 constitutes the coil temperature detection unit in the present invention.

The control device 20 outputs a control signal (PWM signal) to the gate terminals of the six transistors in the inverter 8 and controls the current supplied to the motor 7 by controlling each transistor to control the torque of the motor 7. Control. As described above, the control device 20 has a function of a motor control unit that controls the inverter 8 to drive the motor 7.

As described above, the vehicle 1 includes the AC cable 12, the motor 7 having the coils 7U, 7W, 7V connected to the AC cable 12, and the coil temperature sensor 22 for detecting the coil temperature of the coils 7U, 7W, 7V. It constitutes a equipped system. In this embodiment, the control device 20 calculates the estimated value of the cable temperature of the AC cable 12 as the estimated cable temperature. The control device 20 constitutes the cable temperature estimation device in the present invention.

The AC cable 12 is set so that the degree of change in the cable temperature is smaller than the degree of change in the coil temperature. This is because the AC cable 12 is exposed to air, whereas the coils 7U, 7W, and 7V of the motor 7 are tightly wound and sealed in the slots of the housing. The "degree of change" of the cable temperature and the coil temperature is the slope of the temperature change in this embodiment. As the "degree of change" of the cable temperature and the coil temperature, the amount of change in temperature or the rate of change in temperature may be used.

The control device 20 includes an estimated cable temperature calculation unit 21. The estimated cable temperature calculation unit 21 calculates the estimated cable temperature based on the coil temperature detected by the coil temperature sensor 22. Here, since the cable temperature has a characteristic that the temperature is less likely to change than the coil temperature, the cable temperature changes after the change in the coil temperature. Therefore, the estimated cable temperature calculation unit 21 calculates the estimated cable temperature by performing a smoothing process on the coil temperature with a predetermined degree of smoothing. The smoothing process is a process including a delay filter process and a smoothing process. The delay filter process is a process of delaying the timing of the change in the estimated cable temperature with respect to the change in the coil temperature. The smoothing process is a process of reducing the degree of change in the estimated cable temperature with respect to the degree of change in the coil temperature.

The method of making the degree of change in the estimated cable temperature of the AC cable 12 smaller than the degree of change in the coil temperature is not limited to the above example. For example, as the material of the AC cable 12, a material having a larger specific heat than the material of the coils 7U, 7W, and 7V may be selected. Further, a method of differentiating the cooling method of the AC cable 12 and the cooling method of the coils 7U, 7W, 7V, for example, water cooling and air cooling may be adopted.

The estimated cable temperature calculation unit 21 changes the degree of change in the estimated cable temperature according to the degree of change in the coil temperature. Specifically, the estimated cable temperature calculation unit 21 changes the degree of change in the estimated cable temperature by changing the degree of smoothing used in the smoothing process according to the degree of change in the coil temperature. Here, the degree of smoothing is the strength of the smoothing process. When the degree of smoothing is small, the degree of change in the estimated cable temperature is small. In this embodiment, the smoothing coefficient described later is used as the degree of smoothing.

The estimated cable temperature calculation unit 21 uses the first smoothing degree when the coil temperature is in the rising state and the second smoothing degree when the coil temperature is in the falling state as the smoothing degree of the smoothing process. ing. The degree of smoothing is smaller in the second degree of smoothing than in the first degree of smoothing. Therefore, when the coil temperature is in the rising state, the first degree of smoothing, which has a relatively large degree of smoothing, is applied, so that the degree of change in the estimated cable temperature becomes small. On the other hand, when the coil temperature is in the lowered state, the second degree of smoothing, which has a relatively small degree of smoothing, is applied, so that the degree of change in the estimated cable temperature becomes large.

The operation of calculating the estimated cable temperature by the estimated cable temperature calculating unit 21 in the control device 20 will be described.

In FIG. 3, the estimated cable temperature calculation unit 21 of the control device 20 acquires the coil temperature by the coil temperature sensor 22 installed so as to be able to detect the temperatures of the coils 7U, 7W, and 7V of the motor 7 in step S101.

Next, in step S102, the estimated cable temperature calculation unit 21 compares the coil temperature acquired in step S101 with the previous value, and determines whether or not the coil temperature is rising.

The estimated cable temperature calculation unit 21 proceeds to step S103 when the coil temperature is rising, and proceeds to step S104 when the coil temperature is not rising.

In this embodiment, the estimated cable temperature calculation unit 21 calculates the estimated cable temperature, which is an estimated value of the cable temperature, based on the coil temperature, but the cable temperature is less likely to change in temperature than the coil temperature. Therefore, the estimated cable temperature is calculated by performing a delay filter process on the coil temperature. Further, the filter value is different between when the coil temperature is in the rising state and when it is in the falling state. As a result, the accuracy of calculating the estimated cable temperature can be improved, the motor 7 can be driven to a higher limit temperature, and the motor 7 can be driven to a limit performance determined by the limit temperature.

In step S103, the estimated cable temperature calculation unit 21 sets the delay filter value B when the coil temperature is rising to B = x. x constitutes the first degree of smoothing in the present invention.

In step S104, the estimated cable temperature calculation unit 21 sets the delay filter value B when the coil temperature is not rising as B = y. y constitutes the second degree of smoothing in the present invention.

In step S105, the estimated cable temperature calculation unit 21 calculates the current estimated cable temperature value Y, where A is the coil temperature value, B is the delay filter value, and C is the previous estimated cable temperature value. The previous estimated cable temperature is the estimated cable temperature at the time of the previous calculation in the calculation cycle.

Specifically, in step S105, the estimated cable temperature calculation unit 21 sets the coil temperature as A, the estimated cable temperature calculated this time as Y, and the estimated cable temperature calculated last time as C, as shown in the following formula 1, and estimates the cable. The estimated cable temperature Y is calculated by multiplying the amount of change in temperature by the smoothing coefficient X as the degree of smoothing.

Y = (AC) X + C ... (Formula 1)

Here, the mathematical formula 1 used in step S105 will be described with reference to FIG. FIG. 4 is a diagram illustrating an operation of calculating the estimated cable temperature using Equation 1. In FIG. 4, the estimated cable temperature Y at the time of the current calculation is a value obtained by adding (AC) X, which is the amount of increase up to the time of the current calculation, to the estimated cable temperature C at the time of the previous calculation. Further, at the time of calculating the estimated cable temperature Y this time, the difference between the estimated cable temperature and the coil temperature A is (AC) (1-X), which corresponds to the thinning out of the smoothing process.

Here, as the smoothing coefficient X, a value selected from a plurality of values such as, for example, the first smoothing coefficient = 0.005 or the second smoothing coefficient = 0.001 is used. The first smoothing coefficient constitutes the first smoothing degree in the present invention, and the second smoothing coefficient constitutes the second smoothing degree in the present invention.

In the above formula 1, when (AC)> 0, the estimated cable temperature is in an elevated state. Further, when (AC) <0, the estimated cable temperature is in a falling state. Further, when (AC) = 0, the estimated cable temperature has not changed. In FIG. 4, the horizontal axis showing the passage of time is enlarged and displayed for the sake of explanation. The actual time interval between the previous estimated value and the current estimated value is a short time interval (for example, several m / sec) corresponding to one calculation cycle.

When the estimated cable temperature Y exceeds a predetermined allowable value in step S106, the control device 20 calculates the output limit value of the motor 7 in order to limit the motor output.

The estimated cable temperature calculation unit 21 may estimate the estimated cable temperature Y in step S105 by using the following mathematical formula 2.

Y = AX + C (1-X) ... (Formula 2)

According to the above estimated cable temperature calculation operation, the first smoothing degree (first smoothing coefficient) is used when the coil temperature is in the rising state, and the second smoothing degree (second smoothing degree) is used when the coil temperature is in the falling state. Since the second smoothing coefficient) is used, it becomes easy to maintain the estimated cable temperature Y at a value higher than the actual cable temperature as shown in FIG. As a result, it is possible to prevent the actual cable temperature from exceeding the allowable temperature of the cable or exceeding the limit temperature that limits the motor drive.

Here, FIG. 5 shows the estimated cable temperature Y of this embodiment and the estimated cable temperature as a comparative example when the first degree of smoothing is always used. As shown in FIG. 5, the estimated cable temperature Y is set to the actual cable temperature in both the period of the coil temperature rising state from the time t0 to the time t3 and the period of the coil temperature rising state after the time t1. The estimated cable temperature Y well follows the actual cable temperature while maintaining a higher value.

In the comparative example, the period in which the temperature difference between the estimated cable temperature and the actual cable temperature becomes small becomes long, and there is a possibility that the estimated cable temperature cannot be made higher than the actual cable temperature due to estimation error or disturbance.

On the other hand, in this embodiment, since the timing at which the estimated cable temperature Y rises after the coil temperature starts to fall and reaches the same temperature as the coil temperature is earlier than that in the comparative example, the estimated cable temperature Y at the same timing Therefore, it is easy to maintain the estimated cable temperature Y higher than the actual cable temperature in the period immediately after the estimated cable temperature Y switches from the rising state to the falling state (particularly in the period from time t3 to t4). ..

Here, in the comparative example, the estimated cable temperature gradually rises as compared with the present embodiment during the period (between time t1 and t2) in which the coil temperature drops while the coil temperature is higher than the cable temperature. This is because the difference (AC) between the coil temperature and the estimated cable temperature at the time of the previous calculation becomes smaller after the time t1 when the coil temperature changes from rising to falling, and the slope of the estimated cable temperature becomes smaller than that of this embodiment. This is to slow down. Therefore, the timing at which the estimated cable temperature rises after the coil temperature starts to drop and reaches the same temperature as the coil temperature is later in the comparative example (t3) than in the present embodiment (t2). turn into. As a result, immediately after the estimated cable temperature is switched from the rising state to the falling state, the temperature difference between the estimated cable temperature and the actual cable temperature becomes small, and the slope of the estimated cable temperature becomes blunted. In this case, the actual cable temperature may exceed the estimated cable temperature. In this embodiment, such a state can be avoided.

Here, when the coil temperature rises sharply and the degree of change in the actual cable temperature exceeds the degree of change in the estimated cable temperature, it may not be possible to guarantee the accuracy of following the estimated cable temperature to the actual cable temperature.

Therefore, in the present embodiment, the estimated cable temperature calculation unit 21 further predicts that the degree of increase in the estimated cable temperature will be larger than the predetermined degree of increase after the coil temperature has transitioned from the rising state to the falling state. , The switching from the first degree of smoothing to the second degree of smoothing is restricted until the coil temperature becomes equal to or lower than the estimated cable temperature.

A specific example will be described with reference to FIG. FIG. 6 shows a comparative example of the present embodiment in which the switching from the first smoothing degree to the second smoothing degree is restricted and the comparative example in which the switching from the first smoothing degree to the second smoothing degree is not restricted. show. The estimated cable temperature Y of this embodiment and the modified example shows the same behavior during the period from the time t0 to t1 when the coil temperature suddenly rises, and the behavior is different from the time t1.

In FIG. 6, in the period from time t1 to t2, the coil temperature rises sharply as compared with the period from time t0 to time t1. During this period, the actual cable temperature also tends to rise sharply, so it is necessary to increase the degree of change in the estimated cable temperature. However, as in the comparative example shown in FIG. 6, when only the followability of the estimated cable temperature to the coil temperature is prioritized, the estimated cable temperature also rises excessively (particularly in the period from t2 to t3). In this case, the estimated cable temperature deviates from the actual cable temperature, and the estimated cable temperature for suppressing the temperature rise of the actual cable temperature so that the actual cable temperature does not exceed the allowable temperature limits the driving of the motor 7. Therefore, the temperature threshold is exceeded, and the performance of the motor 7 cannot be brought out to the limit. The purpose of limiting the drive of the motor 7 is to suppress the rise in the actual cable temperature by limiting the drive of the motor 7, and to set the actual cable temperature to a temperature higher than the temperature threshold. It is to prevent it from reaching. This upper limit cable temperature is a temperature threshold value higher than the second temperature threshold value higher than the first temperature threshold value when the temperature threshold value is set to the first temperature threshold value. The second temperature threshold value may be an upper limit value of the rated temperature of the cable or an upper limit temperature for use, or may be set to a temperature threshold value at which the driving of the motor 7 is stopped in order to suppress an increase in the cable temperature. ..

Therefore, in the present embodiment, the estimated cable temperature calculation unit 21 determines that the degree of increase in the estimated cable temperature is expected to be larger than the predetermined degree of increase after the coil temperature has transitioned from the rising state to the falling state. It is preferable to limit the switching from the first degree of smoothing to the second degree of smoothing until the temperature becomes equal to or lower than the estimated cable temperature. The limitation of switching the degree of smoothing is that it is expected that the degree of increase in the estimated cable temperature will be larger than the predetermined degree of increase after the coil temperature has transitioned from the rising state to the falling state in step S102 of FIG. , And, on the condition that the coil temperature becomes equal to or lower than the estimated cable temperature, it is realized by switching to the second smoothing degree in step S104.

The estimated cable temperature calculation unit 21 should be noted that, instead of the control for limiting the switching from the first smoothing degree to the second smoothing degree, or in addition to this control, the coil temperature is in a rising state to a falling state. When the degree of increase in the estimated cable temperature is expected to be larger than the predetermined degree of increase before the transition to (for example, the timing at time t1 when the difference between the coil temperature A and the estimated cable temperature Y becomes greater than or equal to the predetermined value). , The control to increase the first degree of smoothing may be performed.

Here, "when the degree of increase in the estimated cable temperature is expected to be larger than the predetermined degree of increase" means, for example, a situation where the temperature difference between the coil temperature and the estimated cable temperature is large, or a change in the coil or estimated cable temperature. The degree exceeds the set value, and the estimated cable temperature rise time exceeds the set time.

Further, "restricting the switching from the first degree of smoothing to the second degree of smoothing" means, for example, prohibiting the switching from the first degree of smoothing to the second degree of smoothing, the first degree of smoothing. It is to gradually switch from the first degree to the second degree of smoothing, and to reduce the degree of the stepwise change from the first degree of smoothing to the second degree of smoothing.

In this embodiment, the degree of smoothing is set so that the estimated cable temperature becomes equal to or higher than the actual cable temperature while the estimated cable temperature is in the rising state.

In this embodiment, the AC cable 12 has a characteristic that the degree of change in the cable temperature is smaller when the cable temperature is in the falling state than when it is in the rising state. In other words, the AC cable 12 has a specification that the inclination when the cable temperature is lowered is smaller than the inclination when the cable temperature is raised.

Next, with reference to FIG. 7, a more preferable embodiment will be described in comparison with a comparative example which is one of the embodiments of the present invention. In FIG. 7, Y and Y'are the estimated cable temperatures of this embodiment, and the estimated cable temperature Y'shows an example preferable to the estimated cable temperature Y. Note that Y'shows the same behavior as Y during the period from time t0 to t5, and behaves differently from Y after time t5. Further, the estimated cable temperature in the comparative example is when the first smoothing degree is switched to the second smoothing degree in the period immediately after the coil temperature changes from the rising state to the falling state (the period from time t6 to t7). Shows the estimated cable temperature.

In FIG. 7, even if the coil temperature is in a lowered state, the heat transfer from the coils 7U, 7W, 7V to the AC cable 12 during the period when the coil temperature exceeds the estimated cable temperature (the period from time t6 to t7). Increases the cable temperature. Therefore, if the degree of smoothing is switched from the first degree of smoothing to the second degree of smoothing in the period immediately after the coil temperature changes from the rising state to the falling state (the period from time t6 to t7), it becomes a comparative example. As shown, the degree of change in the estimated cable temperature becomes large, the estimated cable temperature becomes high when the coil temperature falls below the estimated cable temperature (time t7), and the difference between the estimated cable temperature and the actual cable temperature becomes large. It ends up. Therefore, in the comparative example, the actual cable temperature may be higher than the estimated cable temperature in the period (the period from time t7 to t8) in which the estimated cable temperature drops due to the coil temperature being lower than the estimated cable temperature. .. Such a state is not preferable because the estimated cable temperature does not include a margin with respect to the actual cable temperature.

Therefore, in this embodiment, the degree of smoothing of the smoothing process is set so that the estimated cable temperatures Y and Y'are higher than the actual cable temperature when the coil temperature is in the rising state. By doing so, the estimated cable temperatures Y and Y'can be made to follow the actual cable temperature at a high temperature with a margin. Further, in the present embodiment, the estimated cable temperature calculation unit 21 keeps the estimated cable temperatures Y and Y'in the rising state after the coil temperature changes from the rising state to the falling state as in the period from time t6 to t7. If so, it is preferable to maintain the smoothing degree used for the smoothing treatment at the first smoothing degree. Further, when the estimated cable temperature calculation unit 21 changes the estimated cable temperatures Y and Y'from the rising state to the falling state after the coil temperature changes from the rising state to the falling state as in the period from time t7 to t8. It is preferable to change the smoothing degree used for the smoothing process from the first smoothing degree to the second smoothing degree. That is, even after the coil temperature has transitioned from the rising state to the falling state at time t6, the estimated cable temperature calculation unit 21 still keeps the estimated cable temperatures Y and Y'in the rising state during the period from time t6 to t7. Since it continues, the degree of smoothing is maintained at the first degree of smoothing, and the temperature is changed to the second degree of smoothing on condition that the estimated cable temperatures Y and Y ′ have transitioned to the descending state at time t7. In step S102 of FIG. 3, the estimated cable temperature calculation unit 21 not only has the coil temperature transitioned to the falling state, but also has the estimated cable temperatures Y and Y ′ transitioning to the falling state as an additional condition. It is preferable to change the smoothing degree from the first smoothing degree to the second smoothing degree in S104. By doing so, the temperature difference between the estimated cable temperature Y, Y ′ and the actual cable temperature when the estimated cable temperature Y, Y ′ transitions from the rising state to the falling state is reduced, and the estimated cable temperature Y, The estimated cable temperatures Y and Y'during the period when Y'is in the descending state can be maintained higher than the actual cable temperature.

In FIG. 7, the coil temperature, the actual cable temperature, and the estimated cable temperatures Y and Y ′ increase at time t0. After that, at time t1, the coil temperature changes from rising to falling, and at time t2, the estimated cable temperatures Y and Y ′ change from rising to falling. After that, the coil temperature changes from a decrease to an increase at time t3, the actual cable temperature changes from a decrease to an increase at time t4, and the estimated cable temperatures Y and Y'change from a decrease to an increase at time t5. Further, at time t6, the coil temperature changes from rising to falling, at time t7, the actual cable temperatures Y and Y'change from rising to falling, and at time t8, the estimated cable temperatures Y and Y'change from rising to falling. ..

In this embodiment, the degree of smoothing is set to a greater degree when a sudden change in the coil temperature is expected than when a sudden change in the coil temperature is not expected.

Here, the "rapid change in coil temperature" refers to a mode of change in which the degree of change in the actual cable temperature exceeds the degree of change in the estimated cable temperature. Further, "when a sudden change in coil temperature is expected" means, for example, a case where the required torque of the motor 7 is large when the rotation speed of the motor 7 is low, or a motor 7 locked state in which the rotor of the motor 7 cannot rotate. It means the case where it is detected.

In FIG. 7, the estimated cable temperature Y indicates a temperature change when the degree of smoothing is increased when the estimated cable temperature is in a sharply falling state. Further, the estimated cable temperature Y'indicates a temperature change when the degree of smoothing is increased not only when the estimated cable temperature is in a sharply falling state but also when it is in a sharply rising state.

In this embodiment, the estimated cable temperature Y is in a sharply falling state during the period from time t2 to t5. In that case, it is preferable that the estimated cable temperature calculation unit 21 increases the degree of smoothing during the period of the sharp drop state. As a result, it is possible to suppress a sharp drop in the estimated cable temperature Y, and it is possible to prevent the estimated cable temperature Y from falling below the actual cable temperature.

In this embodiment, the estimated cable temperature Y'is in a sharply falling state during the period from time t2 to t5, and the estimated cable temperature Y changes from a sharply falling state to a sharply rising state at time t5. There is. In that case, the estimated cable temperature calculation unit 21 increases the degree of smoothing not only in the sudden falling state (period from time t2 to t5) but also in the sudden rising state (period from time t5 to t8). Is more preferable. As a result, even when the estimated cable temperature Y'changes from a sharply falling state to a sharply rising state, the degree of smoothing can be increased to suppress the sharply falling of the estimated cable temperature Y', and the estimated cable temperature Y'can be suppressed. Can be prevented from falling below the actual cable temperature. Such a change in the degree of smoothing is made in step S102 of FIG. 3, whether or not the coil temperature is rising, whether or not the estimated cable temperature is in a sharply falling state, and whether or not the estimated cable temperature is rapidly falling. Is realized by determining whether or not has transitioned from a sharply descending state to a suddenly rising state.

In this embodiment, the control device 20 has an ambient temperature sensor 23 as an ambient temperature detection unit that estimates the ambient temperature of the AC cable 12, and a cable current sensor 24 as a cable current detection unit that detects the current flowing through the AC cable 12. And have. Then, the estimated cable temperature calculation unit 21 corrects the degree of smoothing based on the ambient temperature of the AC cable 12 and the current flowing through the AC cable 12.

In this embodiment, the temperature of the cable of at least one of the cables 12U, 12V, and 12W of the three-phase AC cable 12 that energizes the motor 7 which is a three-phase AC motor is estimated, but the temperature is not limited to this. , Three-phase cables 12U, 12V, 12W may all be estimated for temperature.

Further, in this embodiment, the motor 7 is composed of a three-phase AC motor, but the motor 7 may be a single-phase motor or a multi-phase motor having three or more phases. The present invention can also be applied to the calculation of the estimated cable temperature of the AC cable 12 used for a single-phase motor or a three-phase or more multi-phase motor.

Further, when estimating the cable temperature of a plurality of phases of a cable, the control device 20 may determine that the temperature difference between the estimated cable temperatures between the phases is abnormal when the temperature difference exceeds a predetermined temperature threshold value.

Further, when the motor 7 is a three-phase AC motor and the temperature of the neutral wire cable 7N connected to the neutral point 7C of the motor 7 is estimated, the coil temperature of the three-phase coils 7U, 7W, 7V is used. It is preferable to detect or estimate the neutral point temperature of the neutral point 7C and calculate the estimated cable temperature based on the neutral point temperature. By doing so, the coil heat generated from each of the three-phase coils 7U, 7W, 7V is transferred to one neutral point 7C, so that the temperature of each coil 7U, 7W, 7V changes at the neutral point 7C. It is possible to detect a larger temperature change and improve the estimation accuracy of the temperature rise of the neutral wire cable 7N.

As described above, in the present embodiment, the AC cable 12 is set so that the degree of change in the cable temperature is smaller than the degree of change in the coil temperature. The control device 20 includes an estimated cable temperature calculation unit 21 that calculates an estimated cable temperature by performing a smoothing process on the coil temperature to a predetermined degree of smoothing.

As a result, the estimated cable temperature calculation unit 21 performs a smoothing process on the detected coil temperature to calculate the estimated cable temperature, so that the cable temperature may change due to heat transfer from the coils 7U, 7W, and 7V. However, it is possible to improve the followability of the estimated cable temperature with respect to the actual cable temperature.

Further, in this embodiment, the estimated cable temperature calculation unit 21 changes the degree of change in the estimated cable temperature according to the degree of change in the coil temperature.

Thereby, for example, when the degree of change of the coil temperature is large, the degree of change of the estimated cable temperature can be increased, and the followability of the estimated cable temperature to the coil temperature can be improved.

Further, in this embodiment, the estimated cable temperature calculation unit 21 uses the first smoothing degree when the coil temperature is in the rising state as the smoothing degree of the smoothing process, and when the coil temperature is in the falling state. The second degree of smoothing is used. The degree of smoothing is smaller in the second degree of smoothing than in the first degree of smoothing.

As a result, when the coil temperature is in an elevated state, the first degree of smoothing, which has a relatively large degree of smoothing, is used, so that the degree of change in the estimated cable temperature becomes small, and the estimated cable temperature does not easily approach the upper limit temperature. Become. Therefore, the motor 7 can be driven without limiting the output until just before the upper limit temperature is reached.

Further, when the coil temperature is in a lowered state, the second degree of smoothing, which has a relatively small degree of smoothing, is used, so that the degree of change in the estimated cable temperature becomes large, and the estimated cable temperature with respect to the coil temperature and the actual cable temperature. It is possible to improve the followability of.

Further, in the present embodiment, the estimated cable temperature calculation unit 21 determines that the degree of increase in the estimated cable temperature is expected to be larger than the predetermined degree of increase after the coil temperature has transitioned from the rising state to the falling state. The switching from the first degree of smoothing to the second degree of smoothing is restricted until the temperature becomes equal to or lower than the estimated cable temperature.

As a result, if the degree of increase in the estimated cable temperature is large after the transition from the ascending state to the descending state, switching of the degree of smoothing is restricted and the increase in the degree of change in the estimated cable temperature is restricted. It is possible to prevent the cable temperature from exceeding the upper limit temperature.

In other words, if the estimated cable temperature rises significantly after the transition from the rising state to the falling state, the estimated cable temperature will change immediately after the transition from the first smoothing degree to the second smoothing degree. Although it rises and becomes easy to approach the upper limit temperature, in this embodiment, it is possible to prevent the estimated cable temperature from exceeding the upper limit temperature.

Further, in this embodiment, the degree of smoothing is set to the degree that the estimated cable temperature becomes equal to or higher than the actual cable temperature while the estimated cable temperature is in the rising state.

As a result, it is highly possible that the actual cable temperature is also rising while the estimated cable temperature is rising. Therefore, by setting the degree of smoothing so that the actual cable temperature does not exceed the rated temperature, the actual cable temperature can be increased. It is possible to prevent the temperature from exceeding the rated temperature.

Here, during the period when the coil temperature exceeds the estimated cable temperature, the estimated cable temperature rises even when the coil temperature is in a falling state. Therefore, if the degree of change in the estimated cable temperature is increased by switching the degree of smoothing from the first degree of smoothing to the second degree of smoothing immediately after the coil temperature changes from the rising state to the falling state, the coil temperature is estimated. The estimated cable temperature becomes high when it falls below the cable temperature. Then, the difference between the estimated cable temperature and the actual cable temperature becomes large, and the actual cable temperature becomes higher than the estimated cable temperature during the period when the estimated cable temperature drops because the coil temperature is lower than the estimated cable temperature. It is possible.

Therefore, in this embodiment, the AC cable 12 has a characteristic that the degree of change in the cable temperature is smaller when the cable temperature is in the falling state than in the case where the cable temperature is in the rising state. Further, the degree of smoothing is set so that the estimated cable temperature becomes higher than the actual cable temperature when the coil temperature is in an elevated state. Then, when the estimated cable temperature continues to rise after the coil temperature changes from the rising state to the falling state, the estimated cable temperature calculation unit 21 maintains the smoothing degree used for the smoothing process at the first smoothing degree. If the estimated cable temperature transitions from the rising state to the falling state after the coil temperature changes from the rising state to the falling state, the smoothing degree used for the smoothing process is changed from the first smoothing degree to the second smoothing degree. ..

As a result, the temperature difference between the estimated cable temperature and the actual cable temperature when the estimated cable temperature transitions from the rising state to the falling state is reduced, and the estimated cable temperature during the period when the estimated cable temperature is in the falling state is the actual cable temperature. Can be kept higher than. In addition, it can be made to follow with a margin.

Further, in this embodiment, the degree of smoothing is set to a larger degree when a sudden change in the coil temperature is expected than when a sudden change in the coil temperature is not expected.

This makes it possible to improve the followability of the estimated cable temperature to the actual cable temperature even when the coil temperature rises sharply and then drops sharply, or when the coil temperature drops sharply and then rises sharply. ..

That is, when the coil temperature rises sharply and the degree of change in the actual cable temperature exceeds the degree of change in the estimated cable temperature, the tracking accuracy of the estimated cable temperature cannot be guaranteed. Therefore, when the coil temperature changes suddenly, by reducing the degree of smoothing of the estimated cable temperature, it is possible to improve the followability of the estimated cable temperature immediately after the coil temperature transitions between the rising state and the falling state. ..

Further, in this embodiment, when the estimated cable temperature is in a sharply falling state, the degree of smoothing is increased during the period of the sharply falling state.

As a result, when the estimated cable temperature is in a sharp drop state, the sharp drop in the estimated cable temperature can be suppressed by increasing the degree of smoothing, and the estimated cable temperature can be prevented from falling below the actual cable temperature. ..

Further, in this embodiment, when the estimated cable temperature transitions from a sharply falling state to a sharply rising state, the degree of smoothing is increased during the period of the sharply falling state and the rising state.

As a result, when the estimated cable temperature changes from a sharp drop state to a sharp rise state, the sudden drop in the estimated cable temperature can be suppressed by increasing the degree of smoothing, and the estimated cable temperature falls below the actual cable temperature. It can be suppressed that it ends up.

Further, in this embodiment, an ambient temperature sensor 23 as an ambient temperature detecting unit for estimating the ambient temperature of the AC cable 12 and a cable current sensor 24 as a cable current detecting unit for detecting the current flowing through the AC cable 12 are provided. The degree of smoothing is corrected based on the ambient temperature of the AC cable 12 and the current flowing through the AC cable 12.

As a result, the degree of smoothing is corrected based on the current flowing through the AC cable 12 and the ambient temperature of the AC cable 12, so that the accuracy of the estimated cable temperature can be improved. As a method of calculating the estimated cable temperature, instead of including the current flowing through the AC cable 12 and the ambient temperature of the AC cable 12 as a correction factor for the degree of smoothing, the estimated cable temperature Y that has been smoothed to the coil temperature A. The accuracy of estimating the estimated cable temperature may be improved by adding the amount of temperature rise based on the self-heating of the AC cable 12 and the ambient temperature of the AC cable 12. The amount of temperature rise based on the self-heating of the AC cable 12 may be calculated or estimated based on the current flowing through the AC cable 12, the length of the AC cable 12, and the width (diameter) of the AC cable, or may be stored in advance. It may be calculated based on a map or the like.

Although embodiments of the present invention have been disclosed, it will be apparent to those skilled in the art that modifications may be made without departing from the scope of the invention. All such modifications and equivalents are intended to be included in the following claims.

Further, the present invention may change the degree of smoothing by utilizing some of the controls disclosed in the present embodiment. For example, instead of or in addition to the control that changes the degree of smoothing when the coil temperature is rising and falling, the temperature difference between the coil temperature and the estimated cable temperature or the estimated cable is higher than the coil temperature. The degree of smoothing may be changed depending on whether or not the temperature is high, and at least one of the degree of change in the estimated cable temperature or the degree of change in the coil temperature.

1 Vehicle (system)
7 Motor 12 AC cable (cable)
20 Control device (cable temperature estimation device)
21 Estimated cable temperature calculation unit 22 Coil temperature sensor 23 Peripheral temperature sensor 24 Cable current sensor A Coil temperature B Delay filter value X Smoothing coefficient (smoothing degree)
Y Estimated cable temperature

Claims (10)

With the cable
With a motor having a coil connected to the cable,
It is used in a system equipped with a coil temperature detection unit that detects the coil temperature of the coil.
A cable temperature estimation device that estimates the cable temperature of the cable.
The cable is set so that the degree of change in the cable temperature is smaller than the degree of change in the coil temperature.
A cable temperature estimation device comprising an estimated cable temperature calculation unit that calculates an estimated cable temperature by performing a smoothing process on the coil temperature to a predetermined degree of smoothing. The cable temperature estimation device according to claim 1, wherein the estimated cable temperature calculation unit changes the degree of change in the estimated cable temperature according to the degree of change in the coil temperature. The estimated cable temperature calculation unit
As the degree of smoothing of the above-mentioned smoothing process,
When the coil temperature is in an elevated state, the first degree of smoothing is used.
When the coil temperature is in a lowered state, the second degree of smoothing is used.
The cable temperature estimation device according to claim 1 or 2, wherein the second degree of smoothing has a smaller degree of smoothing than the first degree of smoothing. The estimated cable temperature calculation unit
If the estimated cable temperature is expected to rise more than the predetermined rise after the coil temperature has transitioned from the rising state to the falling state, the coil temperature is said to be equal to or lower than the estimated cable temperature. The cable temperature estimation device according to claim 3, wherein the switching from the first degree of smoothing to the second degree of smoothing is restricted. The degree of smoothing is any one of claims 1 to 4, wherein the degree of smoothing is set so that the estimated cable temperature becomes equal to or higher than the actual cable temperature while the estimated cable temperature is in an elevated state. The cable temperature estimator described in the section. The cable has a characteristic that the degree of change in the cable temperature is smaller when the cable temperature is in the falling state than when the cable temperature is in the rising state.
The degree of smoothing is set so that the estimated cable temperature is higher than the actual cable temperature when the coil temperature is in an elevated state.
The estimated cable temperature calculation unit
When the estimated cable temperature continues to rise after the coil temperature changes from the rising state to the falling state, the smoothing degree is maintained at the first smoothing degree.
When the estimated cable temperature transitions from the rising state to the falling state after the coil temperature changes from the rising state to the falling state, the smoothing degree is changed from the first smoothing degree to the second smoothing degree. 3. The cable temperature estimation device according to claim 3 or 4. The degree of smoothing is set to a larger degree when a sudden change in the coil temperature is expected than when a sudden change in the coil temperature is not expected. The cable temperature estimation device according to claim 6. The cable temperature estimation device according to claim 7, wherein when the estimated cable temperature is in a sharply falling state, the degree of smoothing is increased during the period of the sharply falling state. The cable temperature estimation according to claim 8, wherein when the estimated cable temperature changes from a sharply falling state to a sharply rising state, the degree of smoothing is increased during the period of the sharply falling state and the rising state. Device. An ambient temperature detector that estimates the ambient temperature of the cable, and
A cable current detection unit for detecting the current flowing through the cable is provided.
The cable temperature estimation device according to any one of claims 1 to 9, wherein the smoothing degree is corrected based on the ambient temperature and the current.

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