Parallel channel independent cooling liquid flow rate estimation method, device, and storage medium

Abstract

The present application relates to a kind of parallel waterway independent cooling liquid flow estimation method, equipment and storage medium, the estimation method steps include: at different flow temperature of cooling liquid, test the thermal impedance curve of power device to cooling liquid in calibration;According to the cooling liquid flow of whole vehicle electronic water pump, controller inlet and outlet NTC temperature, power device built-in temperature sensor detection temperature and power loss of power device, query the calibrated thermal impedance curve, determine the inlet and outlet flow of waterway independence;To the independent inlet and outlet flow calculated according to inlet and outlet temperature is averaged, and the cooling liquid flow of waterway independence is estimated.Compared with prior art, the present application can monitor whether the cooling liquid flow of two parallel modules is consistent online, can reduce the temperature difference between parallel single tube, improve the maximum output power of inverter, improve the working life and performance of module.

Description

Technical Field

[0001] This invention relates to the field of motor controller testing technology, and in particular to a method for estimating the flow rate of independent coolant in parallel water channels based on power device temperature data. Background Technology

[0002] The motor controller is a core component of the powertrain of new energy vehicles. The coolant in the powertrain's electric water pump is used for water cooling of the inverter. For inverters with appropriate power density, the power module temperature can be cooled through the inverter's single-loop water channel, and the coolant flow rate can be confirmed by the flow meter of the vehicle's electric water pump. As the market places higher demands on vehicle performance, there is a corresponding need to develop powertrain systems with higher power density. Currently, the power module in the motor controller uses a double-sided water-cooled package. The power module body integrates double-sided cooling water channels, which are sealed by press-fitting the inlet and outlet water channels of the housing, thus connecting the power module water channels in series with the vehicle's electric water pump circuit.

[0003] Single-tube power modules cannot meet the power requirements of the entire vehicle, so a dual-tube power module parallel connection is proposed to improve the inverter's power density. Cooling for dual-tube power modules can be achieved using either a series or parallel water circuit. Traditional series water circuit designs ensure consistent coolant flow rates for both power modules, but the coolant temperatures of the two parallel power tubes differ, leading to variations in their thermal resistance. Given that power IGBTs / SiCs are temperature-sensitive devices, the traditional series water circuit design significantly limits the inverter's maximum power output; therefore, a parallel water circuit design is adopted. This places higher demands on the uniformity of coolant flow rates between the two parallel modules.

[0004] For dual-module applications, parallel cooling channels require splitting the vehicle's single cooling circuit in two at the inverter inlet and merging them at the inverter outlet. Based on the electronic water pump flow rate of the vehicle's single cooling circuit, conventional coolant flow detection would require at least one additional flow meter to measure the independent flow rates of the two parallel cooling circuits. This is not feasible in terms of cost and space for high-power-density inverters. Summary of the Invention

[0005] The purpose of this invention is to provide a method and device for estimating the flow rate of independent coolant in parallel water channels based on power device temperature data.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] As a first aspect of the present invention, a method for estimating the independent coolant flow rate in parallel water channels is provided, the estimation method comprising the following steps:

[0008] The thermal resistance curves of the calibrated power devices to the coolant were tested at different flow rates and temperatures, including the relationship between the thermal resistance of the power device's built-in temperature sensor and the coolant temperature and flow rate.

[0009] Based on the vehicle's electronic water pump coolant flow rate, the NTC temperature at the controller's inlet and outlet, the temperature detected by the power device's built-in temperature sensor, and the power loss of the power device, the calibrated thermal impedance curve is consulted to determine the independent inlet and outlet flow rates of the water channel.

[0010] The independent inlet and outlet flow rates calculated based on the inlet and outlet temperatures are averaged to estimate the independent coolant flow rate of the water channel.

[0011] Furthermore, the estimation method is applied to dual-tube power modules employing parallel water cooling.

[0012] Furthermore, the two power devices in the dual-transistor power module undergo parameter consistency screening.

[0013] Furthermore, the test calibration of the power device's thermal resistance curve to the coolant includes the relationship between the thermal resistance of the power device wafer and the coolant temperature and flow rate.

[0014] Furthermore, the step of calibrating the thermal resistance curve of the power device to the coolant includes:

[0015] Given coolant flow rate and temperature;

[0016] Measure the temperature sensor built into the power device or the terminal voltage V1 of the wafer;

[0017] Turn on the power device, set the forward conduction current I2 and maintain it for the set time; before ending the conduction, measure the terminal voltage V2 of the power device and calculate the power device loss Pwr = I2 * V2;

[0018] Measure the terminal voltage V3 of the temperature sensor or wafer; the terminal voltage of the temperature sensor is measured after measuring the terminal voltage V2 of the power device and before the conduction ends; the terminal voltage of the wafer is measured after the conduction ends and after a set delay.

[0019] Determine the thermal resistance of the temperature sensor or wafer built into the power device to the coolant temperature and flow rate:

[0020]

[0021] In the formula, ΔT represents the temperature rise of the built-in temperature sensor or the wafer, T coef This represents the scaling factor for the linearization of the voltage at the built-in temperature sensor or the wafer voltage with its temperature.

[0022] Furthermore, before making the estimation, the NTC temperature of the coolant channel inlet and outlet is calibrated at different coolant temperatures.

[0023] Furthermore, the coolant temperature used for calibrating the inlet and outlet NTCs is the same as the coolant temperature used for calibrating the thermal impedance curve.

[0024] Furthermore, the step of determining the independent flow rates at the inlet and outlet of the waterway includes:

[0025] Read the total flow rate of the electronic water pump;

[0026] Determine the inlet and outlet temperatures of the coolant in the cooling channel based on the NTC temperatures at the inlet and outlet.

[0027] The MCU reads the temperature from the built-in temperature sensor of the power device at the inlet and outlet.

[0028] Calculate the power loss of the power devices based on the bus voltage, output phase current, and control method.

[0029] Rth_TS(i) is calculated according to the following formula:

[0030] Power*Rth_TS(i)+CoolT(i)=PowerT(i)

[0031] In the formula, Rth_TS(i) represents the thermal resistance from the built-in temperature sensor to the cooling water channel, PowerT(i) represents the sampling temperature of the built-in temperature sensor, and CoolT(i) represents the coolant temperature;

[0032] Based on Rth_TS(i) and CoolT(i), and combined with the thermal impedance relationship between coolant temperature and flow rate obtained from the calibrated temperature sensor, the independent inlet and outlet flow rates of the water channel are calculated.

[0033] As a second aspect of the present invention, an electronic device for flow estimation is provided, comprising:

[0034] One or more processors;

[0035] Memory, used to store one or more programs;

[0036] When the one or more programs are executed by the one or more processors, the one or more processors implement the traffic estimation method as described above.

[0037] As a third aspect of the present invention, a computer-readable storage medium is provided, the computer-readable storage medium storing a computer program, characterized in that, when the computer program is executed by a processor, it implements the steps of the flow estimation method as described above.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] 1) This invention provides a method for determining coolant flow rate based on the temperature data of power devices IGBT / SiC. For the constructed parallel water channels, the coolant flow rate of the two parallel modules is monitored online to ensure consistency. No additional coolant flow rate detection equipment is required, resulting in low detection cost and high space utilization of the drive system. Furthermore, by combining the water flow rate of the vehicle's electronic water pump, the estimated flow rates at the inlet and outlet are normalized to improve detection accuracy.

[0040] 2) The present invention also estimates the wafer temperature based on the estimated coolant flow rate to ensure that the power module operates within the junction temperature safety boundary. Attached Figure Description

[0041] Figure 1 This is a flowchart of the coolant flow estimation method based on IGBT / SiC temperature data of the power device according to the present invention. Detailed Implementation

[0042] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0043] Example 1

[0044] As one example of the present invention, such as Figure 1 As shown, this embodiment provides a method for estimating the independent coolant flow rate of parallel water channels based on the temperature data of power devices IGBT / SiC. Based on thermodynamic principles, a heat conversion model is designed, which includes the relationship between coolant temperature, coolant flow rate, radiator thermal resistance, and power module losses. The module's power loss is related to the bus voltage, output phase current, and control method. Based on the determined inverter operating conditions, the power loss is calculated online, and the coolant flow rate of the inverter is determined by sampling values ​​from the temperature sensor encapsulated inside the power module. This not only meets the inverter's cooling requirements but also avoids limiting the inverter's maximum output power due to differences in coolant flow rate in dual-module applications. The coolant flow rate estimation method includes the following steps:

[0045] Step 1: Calibrate the module's built-in temperature sensors, including temperature diodes or NTCs (Negative Temperature Coefficient Sensors), to the coolant at different flow rates and temperatures of -20℃, 0℃, 25℃, and 65℃, determining the relationship between the thermal resistance of the sensors and the coolant (Rth_TS(CoolFlow, CoolT)) and the thermal resistance of the power device wafer to the coolant (Rth_Die(CoolFlow, CoolT)). The specific calibration steps for determining the thermal resistance of the power device to the coolant temperature and flow rate are as follows:

[0046] The cooling system is configured with a flow rate of 8 LPM and a coolant temperature of 65°C.

[0047] Measure the terminal voltage V1 of the temperature sensor built into the power device;

[0048] Turn on the power device and conduct it in the forward direction with I2 = 80A for 8s. At the 7th and 8th second, measure the terminal voltage V2 of the power device and calculate the power device loss Pwr = I2 * V2.

[0049] At 7.9s, the terminal voltage V3 of the temperature sensor built into the power device was measured.

[0050] Determine the thermal resistance of the power device's built-in diode temperature sensor to coolant temperature and flow rate, in units.

[0051]

[0052] In the formula, ΔT represents the temperature rise of the built-in temperature sensor or the wafer, T coef This represents the scaling factor for the linearization of the voltage at the built-in temperature sensor or the wafer voltage with its temperature.

[0053] Similarly, to determine the thermal resistance of the power device wafer to the coolant temperature and flow rate, unlike temperature sensor calibration, the terminal voltage V3 of the power device wafer is measured 500 microseconds after the conduction ends.

[0054] Step 2: Calibrate the NTC temperature of the coolant inlet and outlet at different temperatures of -20℃, 0℃, 25℃, and 65℃, with a detection accuracy of ±1℃;

[0055] Step 3: Based on the vehicle's electronic water pump coolant flow rate, the NTC temperature at the controller's inlet and outlet, the temperature detected by the power device's built-in temperature sensor, and the power loss of the power device, refer to the calibrated thermal impedance curve to determine the independent flow rate of the parallel water channels. The specific steps are as follows:

[0056] Based on the vehicle's CAN message, read the total flow rate of the electronic water pump, CoolFlow0.

[0057] Determine the coolant inlet temperature (CoolT) based on the NTC temperature at the inlet of the parallel water channel coolant channel. 1_in CoolT 2_in ;

[0058] According to the temperature sensor built into the power device at the inlet, the MCU reads the temperature. 1_in and PowerT 2_in ;

[0059] The power loss of the power devices is calculated based on the bus voltage, output phase current and control method. The parameters of the two parallel power devices are screened for consistency, and the power losses are close.

[0060] Given Power*Rth_TS(i) + CoolT(i) = PowerT(i), where i is either 1 or 2, calculate Rth_TS(i).

[0061] In the formula, Rth_TS(i) represents the thermal resistance from the built-in temperature sensor to the cooling water channel, PowerT(i) represents the sampling temperature of the built-in temperature sensor, and CoolT(i) represents the coolant temperature.

[0062] Based on Rth_TS(i) and CoolT(i), and combined with the relationship between the thermal resistance of the coolant and temperature and flow rate obtained from the temperature sensor calibrated in step 1, the inlet flow rate Flow of the two independent water channels is calculated. 1_in and Flow 2_in ;

[0063] Similarly, the coolant outlet temperature (CoolT) of the two independent coolant channels can be determined based on the NTC temperature at the coolant outlet. 1_out CoolT 2_out ;

[0064] Similarly, the temperature of the PowerT sensor built into the power device at the water outlet is read by the MCU. 1_out and PowerT 2_out ;

[0065] Repeat the above steps to calculate the flow rates at the inlets of the two independent waterways. 1_out and Flow 2_out ;

[0066] Step 4: Consider that the sum of the flow rates of the parallel water channels equals the total flow rate of the vehicle's electric water pump. Averaging the flow rates calculated based on the inlet and outlet temperatures, we obtain:

[0067] Flow1 = (Flow1_in / (Flow 1_in +Flow 2_in )*Flow0+Flow 1_out / (Flow 1_out +Flow 2_out )*Flow0) / 2

[0068] Flow2 = (Flow 2_in / (Flow 1_in +Flow 2_in )*Flow0+Flow 2_out / (Flow 1_out +Flow 2_out )*Flow0) / 2

[0069] Based on the estimated coolant flow rate, the wafer temperature is estimated to ensure that the power module operates within the junction temperature safety boundary.

[0070] Example 2

[0071] As a second aspect of the present invention, this application also provides an electronic device, comprising: one or more processors; a memory for storing one or more programs; wherein when the one or more programs are executed by the one or more processors, the one or more processors implement the coolant flow estimation method described above. In addition to the processors, memory, and interface described above, any data processing device in the embodiments may also include other hardware depending on the actual function of the data processing device, which will not be elaborated further.

[0072] Example 3

[0073] As a third aspect of the present invention, this application also provides a computer-readable storage medium storing computer instructions thereon, which, when executed by a processor, implement the coolant flow estimation method described above. The computer-readable storage medium can be an internal storage unit of any data-processing device as described in any of the foregoing embodiments, such as a hard disk or memory. The computer-readable storage medium can also be an external storage device, such as a plug-in hard disk, smart media card (SMC), SD card, flash card, etc., equipped on the device. Furthermore, the computer-readable storage medium can include both internal storage units of any data-processing device and external storage devices. The computer-readable storage medium is used to store the computer program and other programs and data required by the data-processing device, and can also be used to temporarily store data that has been output or will be output.

[0074] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0075] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for estimating the independent coolant flow rate in parallel water channels, characterized in that, The estimation method includes the following steps: The thermal resistance curves of the calibrated power devices to the coolant were tested at different flow rates and temperatures, including the relationship between the thermal resistance of the power device's built-in temperature sensor and the coolant temperature and flow rate. Based on the vehicle's electronic water pump coolant flow rate, the NTC temperature at the controller's inlet and outlet, the temperature detected by the power device's built-in temperature sensor, and the power loss of the power device, the calibrated thermal impedance curve is consulted to determine the independent inlet and outlet flow rates of the water channel. The specific steps are as follows: Read the total flow rate of the electronic water pump; Determine the inlet and outlet temperatures of the coolant in the cooling channel based on the NTC temperatures at the inlet and outlet. The MCU reads the temperature from the built-in temperature sensor of the power device at the inlet and outlet. Calculate the power loss of the power devices based on the bus voltage, output phase current, and control method. ; Calculate according to the following formula : In the formula, This indicates the thermal resistance from the built-in temperature sensor to the cooling water channel. This indicates the sampling temperature of the built-in temperature sensor. Indicates the coolant temperature; according to and By combining the thermal impedance relationship between coolant temperature and flow rate obtained from the calibrated temperature sensor, the independent inlet and outlet flow rates of the water channel are calculated. The independent inlet and outlet flow rates calculated based on the inlet and outlet temperatures are averaged to estimate the independent coolant flow rate of the water channel.

2. The method for estimating the independent coolant flow rate in parallel water channels according to claim 1, characterized in that, The estimation method is applied to dual-tube power modules that employ parallel water cooling.

3. The method for estimating the independent coolant flow rate in parallel water channels according to claim 2, characterized in that, The two power devices in the dual-transistor power module undergo parameter consistency screening.

4. The method for estimating the independent coolant flow rate in parallel water channels according to claim 1, characterized in that, The thermal impedance curve of the power device to the coolant during the test calibration includes the relationship between the thermal impedance of the power device wafer and the coolant temperature and flow rate.

5. The method for estimating the independent coolant flow rate in parallel water channels according to claim 4, characterized in that, The steps for calibrating the thermal resistance curve of the power device to the coolant include: Given coolant flow rate and temperature; Measuring the temperature sensor built into the power device or the terminal voltage of the wafer. ; Turn on the power device and set the forward conduction current. Maintain the set duration; before ending conduction, measure the voltage at the power device terminals. Calculate the power device losses ; Measuring the terminal voltage of temperature sensors or wafers The terminal voltage of the temperature sensor is at the terminal voltage of the measuring power device. Subsequently, measurements were taken before the conduction was terminated; the terminal voltage of the wafer was measured after the conduction was terminated and a set delay was observed. Determine the thermal resistance of the temperature sensor or wafer built into the power device to the coolant temperature and flow rate: In the formula, This indicates the temperature rise of the built-in temperature sensor or the wafer. This represents the scaling factor for the linearization of the voltage at the built-in temperature sensor or the wafer voltage with its temperature.

6. The method for estimating the independent coolant flow rate in parallel water channels according to claim 1, characterized in that, Before making the estimation, calibrate the NTC temperature of the coolant channel inlet and outlet at different coolant temperatures.

7. The method for estimating the independent coolant flow rate in parallel water channels according to claim 6, characterized in that, The coolant temperature used for calibrating the inlet and outlet NTCs is the same as the coolant temperature used for calibrating the thermal impedance curve.

8. An electronic device for flow estimation, characterized in that, include: One or more processors; Memory, used to store one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the traffic estimation method as described in any one of claims 1-7.

9. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the flow estimation method as described in any one of claims 1-7.

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