Element Near-Side Temperature Estimation Device

Abstract

The software used to estimate the temperature of the cooling medium near the elements in power conversion systems with the same configuration will be identical. [Solution] In a power conversion system in which a switching element for power conversion is cooled by a cooling medium supplied from a cooling medium pump incorporated into a separate system, the element vicinity temperature estimation device estimates the temperature of the cooling medium near the switching element based on the corrected heat generation obtained by multiplying the heat generation due to the loss of the switching element by a flow rate correction coefficient based on the flow rate of the cooling medium supplied by the cooling medium pump obtained from the separate system, and the supply temperature.

Description

Technical Field

[0001] The present disclosure relates to an element-nearby temperature estimation device, and more particularly, to an element-nearby temperature estimation device that estimates the temperature of a cooling medium near a switching element in a power conversion system.

Background Art

[0002] Conventionally, as this type of element-nearby temperature estimation device, there has been proposed one that estimates the temperature of a cooling medium that cools an inverter based on the element temperature of the inverter and the energization current of the inverter (see, for example, Patent Document 1). In this device, it is determined whether or not poor cooling water circulation has occurred based on the temperature difference between the estimated temperature of the cooling medium and the temperature of the cooling medium detected by a temperature sensor attached to the suction port of the cooling medium.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the above-described system, even if the temperature at the inlet of the cooling medium is the same, if the flow rate of the cooling medium is different, the temperature of the cooling medium near the elements of the same power conversion system will also be different. When the cooling medium is supplied from another system, the flow rate of the supplied cooling medium will differ depending on the specifications of the pump for the cooling medium incorporated in the other system. Therefore, even for power conversion systems with the same configuration, it is necessary to install different software for estimating the temperature of the cooling medium near the elements.

[0005] The main object of the element-nearby temperature estimation device of the present disclosure is to make the software for estimating the temperature of the cooling medium near the elements in a power conversion system with the same configuration the same. [Means for solving the problem]

[0006] The device for estimating the temperature near an element of this disclosure employs the following means to achieve the main objective described above.

[0007] The device for estimating the temperature near an element in this disclosure is An element near-circumstance temperature estimation device for estimating the temperature of the cooling medium near a switching element in a power conversion system in which a switching element for power conversion is cooled by a cooling medium supplied from a cooling medium pump incorporated into a separate system, The system includes a temperature sensor that detects the supply temperature of the cooling medium, The temperature of the cooling medium near the switching element is estimated based on the corrected heat generated by multiplying the heat generated due to the loss of the switching element by a cooling water flow rate correction coefficient based on the flow rate of the cooling medium supplied by the cooling medium pump obtained from the separate system, and the supply temperature. It is characterized by the following:

[0008] The element vicinity temperature estimation device of this disclosure estimates the temperature of the cooling medium near a switching element in a power conversion system in which a switching element for power conversion is cooled by a cooling medium supplied from a cooling medium pump incorporated into a separate system. In this case, the temperature of the cooling medium near the switching element is estimated based on the corrected heat generation obtained by multiplying the heat generation due to the loss of the switching element by a cooling water flow rate correction coefficient based on the flow rate of the cooling medium supplied by the cooling medium pump obtained from the separate system, and the supply temperature of the cooling medium detected by a temperature sensor. Specifically, the flow rate of the cooling medium supplied by the cooling medium pump from the separate system is obtained, a cooling water flow rate correction coefficient is determined based on this obtained flow rate of the cooling medium, the corrected heat generation is obtained by multiplying the heat generation due to the loss of the switching element by the cooling water flow rate correction coefficient, and the temperature of the cooling medium near the switching element is estimated based on this corrected heat generation and the supply temperature of the cooling medium detected by a temperature sensor. In this way, the flow rate of the cooling medium supplied by a cooling medium pump from another system is obtained and the cooling water flow rate correction coefficient is determined. Therefore, even if the cooling medium pump of the other system is different, or if the flow path configuration of the cooling medium in the other system is different, the temperature of the cooling medium near the switching element can be estimated using the same software-based element-near-temperature estimation device in a power conversion system with the same configuration. As a result, the software for estimating the temperature of the cooling medium near the element can be the same in a power conversion system with the same configuration. [Brief explanation of the drawing]

[0009] [Figure 1] This diagram shows a schematic configuration of a power conversion system 20 including an element near-temperature estimation device 30 as one embodiment of the present disclosure. [Figure 2] This flowchart shows an example of the element proximity temperature estimation process installed in the element proximity temperature estimation device 30. [Figure 3] This is an explanatory diagram showing an example of a map for setting flow rate correction coefficients. [Modes for carrying out the invention]

[0010] Next, embodiments for implementing this disclosure will be described. Figure 1 is a schematic diagram showing the configuration of a power conversion system 20 including an element near-temperature estimation device 30 as one embodiment of this disclosure. The power conversion system 20 of the embodiment may include, for example, one whose main components are a boost converter and an inverter that boost power from a battery (not shown) to convert it into three-phase AC power and apply it to a motor (not shown), or one whose main components are a DC / DC converter that steps down power from a high-voltage system and supplies it to a low-voltage system.

[0011] The power conversion system 20 of this embodiment has a cooling channel for cooling multiple switching elements of an inverter, boost converter, or DC / DC converter. This cooling channel is connected to a cooling device 12 of another system 10, and receives a cooling medium (e.g., cooling water) from the cooling device 12 of the other system 10. The cooling medium flows through the cooling channel to cool the multiple switching elements, and the cooling medium is returned to the cooling device 12 of the other system 10. The cooling device 12 of the other system 10 has a pump 14 that pumps the cooling medium into the cooling channel.

[0012] The power conversion system 20 of this embodiment includes an element-near-the-element temperature estimation device 30 that estimates the temperature of the cooling medium flowing through the cooling channel near the switching element (for example, directly below the element). The element-near-the-element temperature estimation device 30 has software 32 installed that takes as input the cooling medium temperature Tc from a temperature sensor 34 attached near the inlet of the cooling medium in the cooling channel and the cooling medium supply flow rate (cooling medium flow rate) Qc from another system 10 to estimate the temperature near the switching element (for example, directly below the element).

[0013] Next, the operation of the element-near-temperature estimation device 30 of the power conversion system 20 configured in this embodiment will be described. Figure 2 is a flowchart showing an example of the element-near-temperature estimation process installed in the element-near-temperature estimation device 30. This process is executed repeatedly at predetermined intervals.

[0014] When the element vicinity temperature estimation process is executed, the element vicinity temperature estimation device 30 first acquires the cooling medium temperature Tc and the cooling medium flow rate Qc (step S100). The cooling medium temperature Tc is acquired by inputting the value detected by the temperature sensor 34, and the cooling medium flow rate Qc is acquired from the data transmitted from the separate system 10. In addition to transmitting the cooling medium flow rate Qc itself, the separate system 10 may also transmit the relationship (map) between the duty cycle of the pump 14 and the cooling medium flow rate, as well as the duty cycle of the pump 14 sequentially. In this case, the cooling medium flow rate Qc can be obtained by applying the map to the duty cycle of the pump 41 that is transmitted sequentially.

[0015] Next, the heat generated ΔTsw due to the switching loss of the switching element and the heat generated ΔTon due to the ON loss of the switching element are obtained (step S110), a voltage correction coefficient Kvh is set based on the voltage applied to the power conversion system 20 from a battery or the like (step S120), and a carrier frequency correction coefficient Kcarf is set based on the carrier frequency that drives the switching element (step S130). In the embodiment, the voltage correction coefficient Kvh is set by first determining the relationship between the voltage applied to the power conversion system 20 and the voltage correction coefficient Kvh through experiments or machine learning and storing it as a map for setting the voltage correction coefficient, and then deriving the corresponding voltage correction coefficient Kvh from the map when the voltage applied to the power conversion system 20 is given. In the embodiment, the carrier frequency correction coefficient Kcarf is set by first determining the relationship between the carrier frequency and the carrier frequency correction coefficient Kcarf through experiments or machine learning and storing it as a map for setting the carrier frequency correction coefficient, and then deriving the corresponding carrier frequency correction coefficient Kcarf from the map when the carrier frequency is given.

[0016] Next, the flow rate correction coefficient Kwp is set based on the cooling medium flow rate Qc (step S140). In this embodiment, the flow rate correction coefficient Kwp is set by first determining the relationship between the cooling medium flow rate Qc and the flow rate correction coefficient Kwp through experiments or machine learning, storing it as a flow rate correction coefficient setting map, and then deriving the corresponding flow rate correction coefficient Kwp from the map when the cooling medium flow rate Qc is given. Figure 3 shows an example of the flow rate correction coefficient setting map. As shown in the figure, in the flow rate correction coefficient setting map of this embodiment, the flow rate correction coefficient Kwp decreases as the cooling medium flow rate Qc increases.

[0017] Then, the element heat generation ΔT is calculated using the following equation (1) (step S150), and the temperature Ts of the cooling medium near the switching element is calculated based on the calculated element heat generation ΔT and the cooling medium temperature Tc (step S160), and this process is completed. In this embodiment, the temperature Ts of the cooling medium near the switching element is determined by first obtaining the relationship between the element heat generation ΔT, the cooling medium temperature Tc and the temperature Ts of the cooling medium near the switching element through experiments or machine learning, storing it as a map for setting the temperature near the element, and then deriving the corresponding temperature Ts of the cooling medium near the switching element from the map when the element heat generation ΔT and the cooling medium temperature Tc are given.

[0018] ΔT=Kwp·((ΔTsw·Kcarf·Kvh)+ΔTon) (1)

[0019] In the element-nearby temperature estimation device 30 included in the power conversion system 20 of the embodiment described above, the supply flow rate (cooling medium flow rate) Qc of the cooling medium from the separate system 10 is input, the flow rate correction coefficient Kwp is obtained based on this cooling medium flow rate Qc, and the heat generation of the switching element (the heat generation ΔTsw due to the switching loss multiplied by the carrier correction coefficient Kcarf and the voltage correction coefficient Kvh and added to the heat generation ΔTon due to the ON loss) is multiplied by the flow rate correction coefficient Kwp to obtain the element heat generation ΔT. Based on this element heat generation ΔT and the cooling medium temperature Tc from the temperature sensor 34 attached near the inlet of the cooling medium in the cooling flow path, the temperature Ts of the cooling medium near the switching element is calculated. Therefore, regardless of the specifications and structure of the cooling device 12 of the separate system 10, it is not necessary to change the software 32 installed in the element-nearby temperature estimation device 30. That is, the software 32 for estimating the temperature Ts of the cooling medium near the element in the power conversion system 20 configured to be the same can use the same one.

[0020] The correspondence between the main elements of the embodiment and the main elements of the invention described in the section of means for solving the problems will be described. In the embodiment, the separate system 10 corresponds to the "separate system", the pump 14 corresponds to the "cooling medium pump", the power conversion system 20 corresponds to the "power conversion system", the element-nearby temperature estimation device 30 corresponds to the "element-nearby temperature estimation device", and the temperature sensor 34 corresponds to the "temperature sensor".

[0021] Note that the correspondence between the main elements of the embodiment and the main elements of the invention described in the section of means for solving the problems is an example for specifically explaining the form for implementing the invention described in the section of means for solving the problems in the embodiment, and does not limit the elements of the invention described in the section of means for solving the problems. That is, the interpretation of the invention described in the section of means for solving the problems should be made based on the description in that section, and the embodiment is only a specific example of the invention described in the section of means for solving the problems.

[0022] As described above, the present disclosure has been explained using embodiments. However, the present disclosure is not limited to such embodiments, and it is needless to say that it can be implemented in various forms without departing from the gist of the present disclosure.

Industrial Applicability

[0023] The present disclosure can be used in the manufacturing industry of an element-near temperature estimation device in a power conversion system and the like.

Explanation of Signs

[0024] 10 Another system, 12 Cooling device, 14 Pump, 20 Power conversion system, 30 Element-near temperature estimation device, 32 Software, 34 Temperature sensor.

Claims

[Claim 1] An element near-circumstance temperature estimation device for estimating the temperature of the cooling medium near a switching element in a power conversion system in which a switching element for power conversion is cooled by a cooling medium supplied from a cooling medium pump incorporated into a separate system, The system includes a temperature sensor that detects the supply temperature of the cooling medium, The temperature of the cooling medium near the switching element is estimated based on the corrected heat generated by multiplying the heat generated due to the loss of the switching element by a flow rate correction coefficient based on the flow rate of the cooling medium supplied by the cooling medium pump obtained from the separate system, and the supply temperature. A device for estimating the temperature near an element, characterized by the above features.

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