EMC temperature estimation and torque control method, storage medium and driving circuit

Abstract

The invention relates to a temperature estimation method of an EMC coil. The method comprises the following steps: measuring a direct current IDC flowing through the EMC coil and a phase current of a motor; measuring the surface temperature of a radiator on the circuit board; the current rotating speed of the motor is obtained, a heat transfer equivalent circuit of the circuit board is determined based on the current rotating speed of the motor, and the heat transfer equivalent circuit is composed of coil internal resistance Rcoil, thermal resistance R1 between a coil and a coil shell, thermal resistance R2 between a motor stator and the coil shell and thermal resistance R3 between the coil shell and a radiator; and calculating the junction temperature TCoil of the EMC coil according to the direct current IDC, the phase current and the surface temperature of the radiator based on the heat transfer equivalent circuit. The invention further relates to a motor torque control method, a computer readable storage medium and a motor driving circuit comprising the computer readable storage medium.

Description

Technical Field

[0001] The present application relates to the field of electromagnetic compatibility control of motors, and more specifically, to a temperature estimation method for an EMC coil, a motor torque control method, a computer-readable storage medium, and a motor drive circuit including the computer-readable storage medium. Background Art

[0002] With the continuous development of autonomous driving technology, various electronic devices inside the vehicle need to work together in a relatively crowded electromagnetic spectrum, so it is crucial to set up an electromagnetic compatibility (EMC) system in the electronic devices of the vehicle. The EMC system can ensure the stable operation of electronic devices in the electromagnetic environment and will not interfere with other surrounding devices and systems.

[0003] On the one hand, the EMC system can manage the electromagnetic performance of electronic equipment to suppress the generation of its own electromagnetic interference, and on the other hand, it can improve the resistance to external electromagnetic interference to ensure the reliability and interoperability of equipment under various electromagnetic conditions. This helps maintain the normal operation of electronic equipment in the crowded electromagnetic spectrum and promotes the collaborative work of various devices and systems.

[0004] For example, an EMC coil is usually provided inside the motor drive circuit to improve the electromagnetic compatibility interference capability of the motor drive circuit. However, the inductance value of such an EMC coil usually changes with the temperature, which may affect the performance of the coil. Especially in a high temperature environment, the inductance value and filtering performance of the coil will be weakened, and the insulating material in the coil will also degrade due to the high temperature, eventually causing damage to the electronic devices in the circuit. Therefore, during the use of the EMC system, it is expected to monitor the temperature of the EMC coil in real time. Summary of the invention

[0005] The present application proposes a new temperature estimation method for an EMC coil. The method obtains the DC current and resistance parameters of the coil and corrects and calibrates the thermal resistance and thermal capacitance in the relevant heat transfer equivalent circuit based on the motor speed to calculate the copper loss generated by each thermal resistance and further deduce the temperature difference. Finally, the temperature of the EMC coil is deduced based on the temperature difference and the base temperature.

[0006] According to a first aspect of the present application, a temperature estimation method of an EMC coil is proposed, wherein the EMC coil is connected in series to a transmission line for supplying power from a DC power supply to a drive circuit of a motor, and is used to suppress electromagnetic interference on the transmission line, wherein the EMC coil, the DC power supply, and the transmission line are integrated on a circuit board, and a heat sink is provided on the circuit board, and the method comprises the following steps:

[0007] Step S1, measuring the direct current I_DC flowing through the EMC coil and the phase current of the motor;

[0008] Step S2, measuring the surface temperature T_cooler of the heat sink on the circuit board;

[0009] Step S3, obtaining the current speed of the motor, and determining the heat transfer equivalent circuit of the circuit board based on the current speed of the motor, wherein the heat transfer equivalent circuit is composed of the coil internal resistance R_coil, the thermal resistance R1 between the coil and the coil housing, the thermal resistance R2 between the motor stator and the coil housing, and the thermal resistance R3 between the coil housing and the radiator; and

[0010] Step S4 , calculating the junction temperature T_Coil of the EMC coil based on the heat transfer equivalent circuit according to the DC current I_DC, the phase current, and the surface temperature T_cooler of the heat sink.

[0011] Advantageously, the step S4 further comprises:

[0012] Get the temperature T_Stator of the motor stator; and

[0013] The power consumption P_Stator of the motor stator is calculated based on the temperature difference between the temperature T_Stator of the motor stator and the surface temperature T_cooler of the heat sink and the thermal resistance R2.

[0014] Advantageously, the temperature T_Stator of the motor stator is obtained by looking up a table based on the current rotation speed of the motor and the phase current of the motor.

[0015] Advantageously, the step S4 further comprises:

[0016] Calculating the power consumption P_Coil of the EMC coil based on the DC current I_DC and the coil internal resistance R_coil; and

[0017] The temperature difference ΔT_Coilcase2cool between the coil housing and the heat sink is calculated based on the power consumption P_Coil of the EMC coil, the power consumption P_Stator of the motor stator, and the thermal resistance R3.

[0018] Advantageously, the step S4 further comprises:

[0019] The case temperature T_CoilCase of the EMC coil is calculated based on the temperature difference ΔT_Coilcase2Cool and the surface temperature T_cooler of the heat sink.

[0020] Advantageously, the step S4 further comprises:

[0021] The temperature difference ΔT_Coilcase2Coil between the coil case and the EMC coil is calculated based on the power consumption P_Coil of the EMC coil and the thermal resistance R1.

[0022] Advantageously, the step S4 further comprises:

[0023] The junction temperature T_Coil of the EMC coil is calculated based on the case temperature T_CoilCase of the EMC coil and the temperature difference ΔT_Coilcase2Coil between the coil case and the EMC coil.

[0024] According to a second aspect of the present application, a method for controlling motor torque is also provided, the method comprising:

[0025] estimating the temperature of the EMC coil using the temperature estimation method according to the above; and

[0026] When the temperature of the EMC coil exceeds the upper limit, the motor is derated.

[0027] According to a third aspect of the present application, a computer-readable storage medium is further provided, on which a computer program is stored. The computer program includes program instructions. Advantageously, when the program instructions are executed by a processor, the various steps of the temperature estimation method as described above are implemented.

[0028] According to a fourth aspect of the present application, a motor drive circuit is further provided, the motor drive circuit comprising:

[0029] DC power supply,

[0030] An inverter bridge, the inverter bridge is used to convert a DC signal provided by the DC power supply into an AC signal for driving a motor;

[0031] An EMC coil is arranged on a transmission line between the DC power supply and the inverter bridge; and

[0032] A control unit, the control unit is configured to control the operating state of each switch tube in the inverter bridge, wherein the control unit includes:

[0033] A computer readable storage medium as described above; and

[0034] A processor is configured to execute program instructions stored in the computer-readable storage medium to estimate a junction temperature of the EMC coil.

[0035] According to the temperature estimation method of the EMC coil of the present application, not only the shell temperature of the EMC coil can be estimated, but also its junction temperature can be estimated. Therefore, the motor can be derated in a timely manner in combination with the estimated results of the shell temperature and / or junction temperature of the EMC coil. Compared with the existing temperature detection method based on thermistors, the temperature estimation result of the present application is faster and more accurate, which is of great significance for ensuring the stable operation of the motor and the EMC system. In addition, accurately obtaining the temperature of the EMC coil also helps to optimize the performance of the motor. The characteristics of the motor may be different at different temperatures, and too high or too low temperatures may affect the efficiency and output of the motor. By monitoring the coil temperature, especially its junction temperature and taking corresponding measures (for example, adjusting the operating parameters of the motor or improving the heat dissipation design), it can be ensured that the motor operates within the optimal operating temperature range, thereby improving energy utilization and system performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] By incorporating the accompanying drawings and Figure 1 With reference to the specific implementation methods used to illustrate certain principles of the present application, other features and advantages of the method of the present application will become clear or be described in more detail.

[0037] Figure 1 A schematic diagram of a motor drive circuit provided with an EMC coil is shown.

[0038] Figure 2 A flow chart of a temperature estimation method of an EMC coil according to an exemplary embodiment of the present application is shown.

[0039] Figure 3 A schematic diagram showing a heat transfer equivalent circuit of a motor drive circuit board according to an exemplary embodiment of the present application is shown. DETAILED DESCRIPTION

[0040] The temperature estimation method of the EMC coil according to the present application will be described below with reference to the accompanying drawings and by way of example. In the following description, many specific details are set forth so that a person skilled in the art can more fully understand the present application. However, it is obvious to a person skilled in the art that the present application may be implemented without some of these specific details. Instead, any combination of the following features and elements may be considered to implement the present application, regardless of whether they relate to different embodiments. Therefore, the following aspects, features, embodiments and advantages are for illustrative purposes only and should not be regarded as elements or limitations of the claims.

[0041] An EMC system is usually set up in the motor drive circuit, such as Figure 1As shown in the figure, the EMC system includes an EMC coil connected in series on a transmission line for supplying power from a DC power supply to a drive circuit of a motor, for suppressing electromagnetic interference on the transmission line. In addition to the EMC coil, the EMC system may also include two filter capacitors CS1 and CS2 connected across the positive and negative transmission lines. Figure 1 It is shown in the figure that the EMC coil can be specifically arranged on the positive DC bus KL40 between the positive pole of the DC power supply and the inverter bridge H. The on and off of each switch tube in the inverter bridge H is controlled by means of a controller ECU.

[0042] The EMC coil, DC power supply and transmission line can be integrated on a circuit board. A heat sink is also provided on the circuit board. The heat sink is usually arranged close to the heating element on the circuit board so as to effectively dissipate the heat generated by the heating element to the surrounding environment, thereby preventing the circuit board from overheating and maintaining the normal operation of various components on the circuit board.

[0043] However, when working in a high temperature environment, the performance of the EMC coil will decrease, so it is necessary to monitor its temperature in real time. When the temperature of the EMC coil is detected to be high, a torque limiting / derating control strategy can be implemented on the motor to protect the components in the circuit from high temperature damage.

[0044] In the conventional temperature detection method of EMC coils, an additional thermistor (such as NTC) is usually set near the coil to monitor its temperature. This temperature detection method requires the design of a specific circuit to read the resistance value of the thermistor and convert it into a temperature value, which increases the design cost and complexity of the circuit. In addition, when a certain temperature range is exceeded, the sampling result of the thermistor-based temperature sensor may be wrong, which in turn leads to inaccurate temperature detection results of the EMC coil.

[0045] In view of the above-mentioned defects in the traditional EMC coil temperature detection method, the present application proposes a new EMC coil temperature estimation method. The method obtains the DC current and resistance parameters of the coil and corrects and calibrates the thermal resistance and thermal capacitance in the relevant heat transfer equivalent circuit based on the motor speed to calculate the copper loss generated by each thermal resistance and further deduce the temperature difference. Finally, the temperature of the EMC coil is deduced based on the temperature difference and the base temperature (in the present application, the surface temperature of the heat sink set on the circuit board is taken as the "base temperature").

[0046] Generally, the operating temperature of EMC coils involves two important temperature parameters: "junction temperature" and "shell temperature". Among them, "junction temperature" refers to the actual temperature of the coil wire inside the coil, which is usually caused by the current and resistance of the coil. When current flows through the coil, it causes the wire inside the coil to heat up, thus forming a junction temperature. Junction temperature can be used as an important parameter to evaluate the performance and life of EMC coils. When the junction temperature is too high, it means that the coil is overheated, and the motor needs to be derated to avoid damage to the coil components and performance degradation.

[0047] "Case temperature" refers to the temperature outside the EMC coil, which usually refers to the surface temperature of the outer shell or external package of the coil. The case temperature is usually transmitted to the outside of the coil by the junction temperature, and can also be affected by the external ambient temperature. The case temperature is very important for the operating environment of the EMC coil because it can affect other components and equipment around the coil. When the case temperature is too high, it may have a thermal impact on the equipment around the coil and even cause safety problems. Therefore, in practical applications, it is necessary to try to ensure that the case temperature of the coil is within an acceptable range.

[0048] According to the temperature estimation method of the present application, both the shell temperature and the junction temperature of the EMC coil can be estimated, so that the motor can be derated in a timely manner in combination with the estimation results of the shell temperature and / or junction temperature of the EMC coil.

[0049] Figure 2 FIG. 1 is a flow chart showing a temperature estimation method of an EMC coil according to an exemplary embodiment of the present application. Figure 1 This article introduces the location of the EMC coil in the motor drive circuit. Figure 2 The various operating steps of the temperature estimation method of the EMC coil are introduced in detail.

[0050] First, the direct current I_DC flowing through the EMC coil and the phase current of the motor are measured in step S1, and the surface temperature T_cooler of the heat sink on the circuit board is measured in step S2.

[0051] Then, in step S3, the current speed of the motor is obtained, and the heat transfer equivalent circuit of the circuit board is determined based on the current speed of the motor. The heat transfer equivalent circuit can be found in Figure 3 , which is composed of the coil internal resistance R_coil, thermal resistances R1, R2, R3 and thermal capacitances C1 and C2.

[0052] Among them, R1 is the thermal resistance between the coil and the coil housing, C1 is the thermal capacitance between the coil and the coil housing, R2 is the thermal resistance between the motor stator and the coil housing, R3 is the thermal resistance between the coil housing and the radiator, C3 is the thermal capacitance between the coil housing and the radiator, I_DC is the DC current of the EMC coil, and R_coil is the internal resistance of the EMC coil. Here, the thermal resistances R1, R2, R3 and the thermal capacitances C1 and C2 are all functions of the motor speed. By substituting the real-time motor speed into the pre-calibrated lookup table, the various thermal capacitance and thermal resistance parameters in the heat transfer equivalent circuit can be determined.

[0053] After determining the heat transfer equivalent circuit, the junction temperature T_Coil of the EMC coil can be estimated in step S4 based on the heat transfer equivalent circuit according to the DC current I_DC, the phase current and the surface temperature T_cooler of the heat sink. The specific operation flow of step S4 is as follows:

[0054] First, the temperature T_Stator of the motor stator can be obtained, which can be obtained based on the current speed of the motor and the phase current of the motor by looking up the table. The power consumption P_Stator of the motor stator can be further calculated based on the temperature difference between the temperature T_Stator of the motor stator and the surface temperature T_cooler of the heat sink and the thermal resistance R2:

[0055] P_Stator=(T_Stator-T_Cooler) / R2.

[0056] Based on the DC current I_DC and the coil internal resistance R_coil, the power consumption of the EMC coil can be calculated as P_Coil = I_DC 2 *R_coil.

[0057] Based on the power consumption P_Coil of the EMC coil, the power consumption P_Stator of the motor stator, and the thermal resistance R3, the temperature difference ΔT_Coilcase2cool between the coil housing and the heat sink can be further calculated:

[0058] ΔT_Coilcase2cool=(P_Coil+P_Stator)*R3

[0059] Finally, based on the temperature difference ΔT_Coilcase2cool and the surface temperature T_cooler of the radiator, the case temperature T_CoilCase=T_Cooler+ΔT_Coilcasr2Coil of the EMC coil can be calculated. The case temperature T_CoilCase can be used as a criterion for evaluating the working condition of the coil.

[0060] As a preferred example, the temperature difference ΔT_Coilcasr2Coil=P_CoilR1 between the coil housing and the EMC coil can be further calculated based on the power consumption P_Coil and the thermal resistance R1 of the EMC coil, and the junction temperature T_Coil of the EMC coil can be finally calculated based on the shell temperature T_CoilCase of the EMC coil and the temperature difference ΔT_Coilcase2Coil between the coil housing and the EMC coil:

[0061] T_Coil=T_CoilCase+ΔT_Coilcase2Coil.

[0062] The junction temperature T_Coil is one of the key indicators to measure the working status of the ECM coil, which reflects the heat distribution and heat dissipation efficiency inside the coil. By accurately monitoring the junction temperature, operators can understand the heat accumulation of the coil in real time to avoid performance degradation or even damage caused by overheating. This helps to extend the life of the motor and EMC system, reduce maintenance costs and system downtime.

[0063] In summary, according to the temperature estimation method of the EMC coil of the present application, not only the shell temperature of the EMC coil can be estimated, but also its junction temperature can be estimated. Therefore, the motor can be derated in a timely manner in combination with the estimated results of the shell temperature and / or junction temperature of the EMC coil. Compared with the existing temperature detection method based on thermistors, the temperature estimation result of the present application is faster and more accurate, which is of great significance for ensuring the stable operation of the motor and the EMC system. In addition, accurately obtaining the temperature of the EMC coil also helps to optimize the performance of the motor. The characteristics of the motor may be different at different temperatures, and too high or too low temperatures may affect the efficiency and output of the motor. By monitoring the coil temperature, especially its junction temperature and taking corresponding measures (for example, adjusting the operating parameters of the motor or improving the heat dissipation design), it can be ensured that the motor operates within the optimal operating temperature range, thereby improving energy utilization and system performance.

[0064] In an exemplary embodiment of the present application, a method for controlling motor torque is also provided, which estimates the temperature of the EMC coil by using the temperature estimation method described in any embodiment of the present invention, wherein when the temperature of the EMC coil exceeds an upper limit value, a derating operation can be performed on the motor.

[0065] In another exemplary embodiment of the present application, a computer-readable storage medium is provided on which a computer program is stored. The program includes executable program instructions, which can implement the various steps of the temperature estimation method described in any embodiment of the present invention when executed by, for example, a processor.

[0066] In another exemplary embodiment of the present application, a motor drive circuit is further provided, which includes: a DC power supply; an inverter bridge, the inverter bridge is used to convert a DC signal provided by the DC power supply into an AC signal for driving a motor; an EMC coil, which is arranged on a transmission line between the DC power supply and the inverter bridge; and a control unit, the control unit is configured to control the operating state of each switch tube in the inverter bridge, wherein the control unit includes: a computer-readable storage medium as described in any embodiment of the present invention; and a processor, the processor is configured to execute program instructions stored in the computer-readable storage medium to estimate the junction temperature of the EMC coil.

[0067] It will be appreciated by those skilled in the art that the method steps described in the present application can be performed in a given order. However, it should be noted that different orders are also possible. The method may include additional method steps that are not listed. In addition, one or more of the method steps may be performed once or repeatedly. In addition, two or more of the method steps may be performed simultaneously or in a temporally overlapping manner. In addition, in the present application, terms such as "comprising" and "including" indicate that in addition to having steps that are directly and clearly stated in the specification and claims, the technical solution of the present application does not exclude the situation of having other steps that are not directly or clearly stated.

[0068] In addition, it can be understood by those skilled in the art that the example implementation of this document can be implemented by software or by combining software with necessary hardware. Therefore, the technical solution according to the implementation of the present application can be embodied in the form of a software product, which can be stored in a non-volatile storage medium or on a network, including several instructions to enable a computing device (which can be a personal computer, a server, or a network device, etc.) to execute the temperature estimation method according to the implementation of the present application.

[0069] Although the present application has been disclosed as above with preferred embodiments, the present application is not limited thereto. Any changes and modifications made by any person skilled in the art without departing from the spirit and scope of the present application should be included in the protection scope of the present application, and therefore the protection scope of the present application should be subject to the scope defined by the claims.

Claims

1. A temperature estimation method for an EMC coil, wherein the EMC coil is connected in series to a transmission line for supplying power from a DC power supply to a drive circuit of a motor, and is used to suppress electromagnetic interference on the transmission line, wherein the EMC coil, the DC power supply, and the transmission line are integrated on a circuit board, and a heat sink is provided on the circuit board, wherein: The method comprises the following steps: Step S1, measuring the direct current I_DC flowing through the EMC coil and the phase current of the motor; Step S2, measuring the surface temperature T_cooler of the heat sink on the circuit board; Step S3, obtaining the current speed of the motor, and determining the heat transfer equivalent circuit of the circuit board based on the current speed of the motor, wherein the heat transfer equivalent circuit is composed of the coil internal resistance R_coil, the thermal resistance R1 between the coil and the coil housing, the thermal resistance R2 between the motor stator and the coil housing, and the thermal resistance R3 between the coil housing and the radiator; as well as Step S4 , calculating the junction temperature T_Coil of the EMC coil based on the heat transfer equivalent circuit according to the DC current I_DC, the phase current, and the surface temperature T_cooler of the heat sink.

2. The temperature estimation method of the EMC coil according to claim 1, characterized in that: The step S4 further comprises: Get the temperature T_Stator of the motor stator; and The power consumption P_Stator of the motor stator is calculated based on the temperature difference between the temperature T_Stator of the motor stator and the surface temperature T_cooler of the heat sink and the thermal resistance R2.

3. The temperature estimation method of the EMC coil according to claim 2, characterized in that: The temperature T_Stator of the motor stator is obtained by looking up a table based on the current rotation speed of the motor and the phase current of the motor.

4. The temperature estimation method of the EMC coil according to claim 2 or 3, characterized in that: The step S4 further comprises: Calculating the power consumption P_Coil of the EMC coil based on the DC current I_DC and the coil internal resistance R_coil; and The temperature difference ΔT_Coilcase2cool between the coil housing and the heat sink is calculated based on the power consumption P_Coil of the EMC coil, the power consumption P_Stator of the motor stator, and the thermal resistance R3.

5. The temperature estimation method of the EMC coil according to claim 4, characterized in that: The step S4 further comprises: The case temperature T_CoilCase of the EMC coil is calculated based on the temperature difference ΔT_Coilcase2cool and the surface temperature T_cooler of the heat sink.

6. The temperature estimation method of the EMC coil according to claim 5, characterized in that: The step S4 further comprises: The temperature difference ΔT_Coilcase2Coil between the coil case and the EMC coil is calculated based on the power consumption P_Coil of the EMC coil and the thermal resistance R1.

7. The temperature estimation method of the EMC coil according to claim 6, characterized in that: The step S4 further comprises: The junction temperature T_Coil of the EMC coil is calculated based on the case temperature T_CoilCase of the EMC coil and the temperature difference ΔT_Coilcase2Coil between the coil case and the EMC coil.

8. A method for controlling motor torque, characterized in that: The method includes: estimating the temperature of the EMC coil using the temperature estimation method according to any one of claims 1 to 7; and When the temperature of the EMC coil exceeds the upper limit, the motor is derated.

9. A computer-readable storage medium having a computer program stored thereon, the computer program comprising program instructions, characterized in that: When the program instructions are executed by a processor, the steps of the temperature estimation method according to any one of claims 1 to 7 are implemented.

10. A motor drive circuit, characterized in that: The motor drive circuit includes: DC power supply, An inverter bridge, the inverter bridge is used to convert a DC signal provided by the DC power supply into an AC signal for driving a motor; An EMC coil is arranged on a transmission line between the DC power supply and the inverter bridge; and A control unit, the control unit is configured to control the operating state of each switch tube in the inverter bridge, wherein the control unit includes: - A computer readable storage medium according to claim 9; and - a processor configured to execute program instructions stored in the computer-readable storage medium to estimate a junction temperature of the EMC coil.

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