Motor temperature evaluation method and device

Abstract

The invention provides a motor temperature evaluation method and device, and the method comprises the steps: obtaining the environment temperature of a motor, the copper loss of an inner stator winding in a previous period, the temperature of the inner stator winding in the previous period, and the DC current value and DC voltage value of any phase of the motor in a current period; taking a direct current value of any phase of the motor in the current period as a first direct current value, taking a direct current voltage value belonging to the same phase as the first direct current value in the current period as a first direct current voltage value, and calculating the resistance value of the stator winding in the current period according to the first direct current value and the first direct current voltage value, evaluating the temperature of the inner stator winding in the current period based on the environment temperature, the copper loss of the inner stator winding in the previous period, the evaluation temperature of the inner stator winding in the previous period and the resistance value of the inner stator winding in the current period; the method is suitable for online evaluation of the temperature of the stator winding in different working states of different types of motors, and the accuracy of estimation of the temperature of the stator winding is improved.

Description

Technical Field

[0001] The present application relates to the technical field of motor temperature monitoring, and in particular to a method and device for evaluating motor temperature. Background Art

[0002] Online monitoring of motor temperature can provide effective thermal protection for motor operation, which is beneficial to reduce motor failure rate and ensure motor operation life. According to different temperature acquisition principles, temperature monitoring methods mainly include direct measurement method, motor thermal model method and stator resistance signal injection temperature estimation method.

[0003] At present, the direct measurement method requires the installation of temperature sensors inside the motor to obtain the motor temperature parameters through measurement. However, due to the number and installation position of the temperature sensors, the direct measurement method cannot fully reflect the internal temperature of the motor. The motor thermal model method and the stator resistance signal injection temperature estimation method realize motor temperature monitoring through algorithms. The motor thermal model method is currently mainly used in the low-speed operation range of the motor. At this time, the stator voltage drop is the same as the back electromotive force level, and the stator resistance identification accuracy is relatively high. For medium and high-speed running motors, the stator voltage drop is much smaller than the motor back electromotive force, resulting in a large stator resistance identification error, which is not suitable for temperature estimation and motor thermal protection. The stator resistance signal injection temperature estimation method performs short-term DC excitation on the series-connected motor phases, and the motor controller or integrated protector realizes the injection of the required signal, and performs temperature analysis based on the injection signal and the excitation signal. No additional hardware equipment needs to be installed, and the operation is simple. It has been widely verified in industrial motors.

[0004] However, the stator resistance signal injection temperature estimation method in the related art is implemented based on the first-order thermal model. In the first-order thermal model, the system is assumed to be adiabatic during the signal injection period (that is, the heat exchange from the stator winding to other parts of the motor can be ignored, the winding copper loss is linearly related to the winding temperature, and the slope of the straight line is the motor heat capacity in the first-order thermal model). This assumption is only applicable to the case where the temperature rise of the stator winding during the injection period is small (3 to 5°C), and the stator winding heat capacity and stator winding thermal resistance derived based on this assumption depend to a large extent on the duration of the test and the temperature rise within the selected time. Obviously, during the motor starting, acceleration and other processes, and for motors using liquid cooling systems, the first-order thermal model cannot accurately estimate the temperature. Therefore, the stator resistance signal injection temperature estimation method in the related art cannot accurately estimate the transient temperature of high-power motors using liquid cooling or with low thermal inertia, and the estimation deviation is large when the motor is accelerating or decelerating. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, the present application provides a motor temperature evaluation method and device to solve the above-mentioned technical problems.

[0006] According to one aspect of an embodiment of the present application, a method for evaluating motor temperature is provided, the method comprising: obtaining the ambient temperature of the motor, the copper loss of the stator winding in the previous cycle, the temperature of the stator winding in the previous cycle, and the DC current value and DC voltage value of any phase of the motor in the current cycle; taking the DC current value of any phase of the motor in the current cycle as the first DC current value, and taking the DC voltage value of the same phase as the first DC current value in the current cycle as the first DC voltage value; calculating the stator winding resistance in the current cycle according to the first DC current value and the first DC voltage value; and evaluating the stator winding temperature in the current cycle based on the ambient temperature, the stator winding copper loss in the previous cycle, the evaluated temperature of the stator winding in the previous cycle, and the stator winding resistance in the current cycle.

[0007] In one embodiment of the present application, before obtaining the DC current value and DC voltage value of any phase of the motor in the current cycle, the method includes: sampling the three-phase current of the motor in the current cycle to obtain a three-phase current sampling signal; and sampling the three-phase voltage of the motor in the current cycle to obtain a three-phase voltage sampling signal; selecting any one of the three phases as the target phase, separating the DC current signal and the AC current signal in the target phase current sampling signal to obtain the first DC current value, and separating the DC voltage signal and the AC voltage signal in the target phase voltage sampling signal to obtain the first DC voltage value.

[0008] In one embodiment of the present application, before sampling the three-phase current of the motor in the current cycle and sampling the three-phase voltage of the motor in the current cycle, the method includes: obtaining the current timing moment; if the current timing moment has not reached the start moment of the current cycle, continuing the timing until the subsequent moment reaches the start moment; if the current timing moment reaches the start moment, or the subsequent moment reaches the start moment, injecting a DC signal into the three-phase stator circuit of the motor to perform signal excitation on the three-phase stator circuit of the motor.

[0009] In one embodiment of the present application, before obtaining the stator winding copper loss in the previous cycle, the method includes: obtaining the DC current value and DC voltage value of any phase of the motor in the previous cycle; taking the DC current value of any phase of the motor in the previous cycle as the second DC current value, and taking the DC voltage value belonging to the same phase as the second DC current value in the previous cycle as the second DC voltage value; and calculating the stator winding copper loss in the previous cycle based on the second DC current value and the second DC voltage value.

[0010] In one embodiment of the present application, the calculation formula for the stator winding copper loss in the previous cycle includes: Among them, P k-1Indicates the stator winding copper loss in the previous cycle, U DC (k-1) represents the second DC voltage value, I DC (k-1) represents the second direct current value.

[0011] In one embodiment of the present application, the calculation formula of the stator winding resistance in the current cycle includes: R k =U DC (k) / 2I DC (k), where R k Indicates the stator winding resistance in the current cycle, U DC (k) represents the first DC voltage value, I DC (k) represents the first direct current value.

[0012] In one embodiment of the present application, the calculation formula for the stator winding temperature in the current cycle includes: Among them, θ k Indicates the stator winding temperature in the current cycle, θ k-1 Indicates the stator winding temperature in the previous cycle, θ 0 Indicates the ambient temperature, R k Indicates the stator winding resistance in the current cycle, P k-1 It represents the copper loss of stator winding in the previous cycle, Δt represents the time interval of DC voltage signal injection, and τ represents the thermal time constant of the motor.

[0013] According to one aspect of an embodiment of the present application, a motor temperature evaluation device is provided, the device comprising: an information acquisition module, used to obtain the ambient temperature of the motor, the copper loss of the stator winding in the previous cycle, the temperature of the stator winding in the previous cycle, and the DC current value and DC voltage value of any phase of the motor in the current cycle; an information processing module, used to take the DC current value of any phase of the motor in the current cycle as the first DC current value, and take the DC voltage value of the same phase as the first DC current value in the current cycle as the first DC voltage value; a resistance calculation module, used to calculate the stator winding resistance in the current cycle according to the first DC current value and the first DC voltage value; a temperature evaluation module, used to evaluate the stator winding temperature in the current cycle based on the ambient temperature, the stator winding copper loss in the previous cycle, the stator winding evaluation temperature in the previous cycle, and the stator winding resistance in the current cycle.

[0014] In one embodiment of the present application, the device includes: a signal injection module, which is used to inject a DC signal into the three-phase stator circuit of the motor when the current timing time reaches the start time of the current cycle to perform signal excitation on the three-phase stator circuit of the motor; a signal sampling and separation module, which is used to sample the three-phase current of the motor in the current cycle after the DC signal is injected into the three-phase stator circuit of the motor to obtain a three-phase current sampling signal, and to sample the three-phase voltage of the motor in the current cycle to obtain a three-phase voltage sampling signal; select any one of the three phases as the target phase, separate the DC current signal and the AC current signal in the target phase current sampling signal to obtain the first DC current value, and separate the DC voltage signal and the AC voltage signal in the target phase voltage sampling signal to obtain the first DC voltage value.

[0015] In one embodiment of the present application, the signal injection module includes: a first DC power supply, a second DC power supply and a DC signal input module; the positive electrode of the first DC power supply is connected to the first end of the first resistor, the second end of the first resistor is connected to the first end of the first inductor, the second end of the first inductor is connected to the first end of the second resistor, the negative electrode of the first DC power supply is connected to the first end of the third resistor, the second end of the third resistor is connected to the first end of the second inductor, and the second end of the second inductor is connected to the first end of the second resistor; the positive electrode of the second DC power supply is connected to the first end of the fourth resistor, the second end of the fourth resistor is connected to the first end of the third inductor, the second end of the third inductor is connected to the first end of the second resistor, and the negative electrode of the second DC power supply is connected to the second end of the second resistor; the DC signal input module is connected to the three-phase stator circuit of the motor, and is used to input the voltage difference signal between the first end of the first resistor and the first end of the third resistor as the DC signal into the three-phase stator circuit of the motor.

[0016] Beneficial effects of the present application: The present application obtains the ambient temperature of the motor, the copper loss of the stator winding in the previous cycle, the temperature of the stator winding in the previous cycle, the DC current value and the DC voltage value of any phase of the motor in the current cycle, and uses the DC current value of any phase of the motor in the current cycle as the first DC current value, and uses the DC voltage value of the same phase as the first DC current value in the current cycle as the first DC voltage value, and calculates the stator winding resistance in the current cycle according to the first DC current value and the first DC voltage value, based on the ambient temperature, the copper loss of the stator winding in the previous cycle, the stator winding temperature in the previous cycle, and the DC current value and DC voltage value of any phase of the motor in the current cycle. The stator winding temperature in the current cycle is evaluated based on the winding evaluation temperature and the stator winding resistance in the current cycle. The above process fully considers the heat exchange between the electronic winding and other parts of the motor, and is based on the ambient temperature, the stator winding copper loss in the previous cycle, the stator winding evaluation temperature in the previous cycle, the DC current value and the DC voltage value of any phase of the motor in the current cycle. The stator winding temperature in the current cycle is evaluated. It is suitable for online evaluation of the stator winding temperature under different working conditions of different types of motors, and improves the accuracy of estimating the stator winding temperature.

[0017] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings herein are incorporated into the specification and constitute a part of the specification, showing embodiments consistent with the present application, and together with the specification, are used to explain the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application, and for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0019] Figure 1 is a schematic diagram of an exemplary system architecture shown in an exemplary embodiment of the present application;

[0020] Figure 2 is a flow chart of a motor temperature evaluation method shown in an exemplary embodiment of the present application;

[0021] Figure 3 is a flow chart of a motor temperature evaluation method shown in another exemplary embodiment of the present application;

[0022] Figure 4 A block diagram of a motor temperature evaluation device suitable for implementing an embodiment of the present application is shown;

[0023] Figure 5 is an architectural diagram of a motor control system shown in an exemplary embodiment of the present application;

[0024] Figure 6is a schematic diagram of a signal injection circuit shown in an exemplary embodiment of the present application;

[0025] Figure 7 A schematic diagram of the structure of a computer system suitable for implementing a motor controller according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0026] Here, exemplary embodiments will be described in detail, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are only examples of devices and methods consistent with some aspects of the present application as detailed in the attached claims.

[0027] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities may be implemented in software form, or in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0028] The flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps can be decomposed, and some operations / steps can be combined or partially combined, so the actual execution order may change according to actual conditions.

[0029] The term "multiple" as used in this application refers to two or more than two. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the related objects are in an "or" relationship.

[0030] The technical solution of the embodiment of the present application involves related technologies such as material loading and unloading management, which is specifically described through the following embodiments:

[0031] Figure 1 It is a schematic diagram of an exemplary system architecture shown in an exemplary embodiment of the present application.

[0032] Reference Figure 1As shown, the system architecture may include a storage device 101 and a motor controller 102. The motor controller 102 may be at least one of a desktop graphics processing unit (GPU) computer, a GPU computing cluster, a neural network computer, etc. Relevant technicians may use the motor controller 102 to obtain the ambient temperature of the motor, the copper loss of the stator winding in the previous cycle, the temperature of the stator winding in the previous cycle, the DC current value and the DC voltage value of any phase of the motor in the current cycle, and use the DC current value of any phase of the motor in the current cycle as the first DC current value, and use the DC voltage value of the same phase as the first DC current value in the current cycle as the first DC voltage value, calculate the stator winding resistance in the current cycle according to the first DC current value and the first DC voltage value, and evaluate the stator winding temperature in the current cycle based on the ambient temperature, the copper loss of the stator winding in the previous cycle, the stator winding evaluation temperature in the previous cycle, and the stator winding resistance in the current cycle. The storage device 101 is used to store the ambient temperature of the motor, the copper loss of the stator winding in the previous cycle, the temperature of the stator winding in the previous cycle, and the DC current value and DC voltage value of any phase of the motor in the current cycle. In this embodiment, the storage device 101 uses a random access memory (RAM) to store the ambient temperature of the motor, the copper loss of the stator winding in the previous cycle, the temperature of the stator winding in the previous cycle, and the DC current value and DC voltage value of any phase of the motor in the current cycle, and provides them to the motor controller 102 for processing.

[0033] In an illustrative manner, after the motor controller 102 obtains the ambient temperature of the motor in the storage device 101, the copper loss of the stator winding in the previous cycle, the temperature of the stator winding in the previous cycle, and the DC current value and DC voltage value of any phase of the motor in the current cycle, the motor controller 102 uses the DC current value of any phase of the motor in the current cycle as the first DC current value, and uses the DC voltage value of the same phase as the first DC current value in the current cycle as the first DC voltage value, and calculates the stator winding resistance in the current cycle based on the first DC current value and the first DC voltage value, and based on the ambient temperature, the copper loss of the stator winding in the previous cycle, and the temperature of the stator winding in the previous cycle, the DC current value of any phase of the motor in the current cycle and the DC voltage value. The stator winding evaluation temperature within a cycle and the stator winding resistance within the current cycle are used to evaluate the stator winding temperature within the current cycle. The above process fully considers the heat exchange between the electronic winding and other parts of the motor, and is based on the ambient temperature, the stator winding copper loss in the previous cycle, the stator winding evaluation temperature in the previous cycle, the DC current value and the DC voltage value of any phase of the motor in the current cycle. The stator winding temperature within the current cycle is evaluated. It is suitable for online evaluation of the stator winding temperature under different working conditions of different types of motors, and improves the accuracy of estimating the stator winding temperature.

[0034] It should be noted that the motor temperature evaluation method provided in the embodiment of the present application is generally executed by the motor controller 102 , and accordingly, the motor temperature evaluation device is generally disposed in the motor controller 102 .

[0035] The implementation details of the technical solution of the embodiment of the present application are described in detail below:

[0036] Figure 2 is a flow chart of a motor temperature evaluation method shown in an exemplary embodiment of the present application. The motor temperature evaluation method can be executed by a computing processing device. The computing processing device can be Figure 1 The motor controller 102 shown in FIG. Figure 2 As shown, the motor temperature evaluation method at least includes steps S210 to S240, which are described in detail as follows:

[0037] In step S210, the ambient temperature of the motor, the copper loss of the stator winding in the previous cycle, the temperature of the stator winding in the previous cycle, and the DC current value and DC voltage value of any phase of the motor in the current cycle are obtained. In one embodiment of the present application, during the operation of the motor, the ambient temperature is obtained in real time through a temperature sensor, etc., the copper loss of the stator winding in the previous cycle and the temperature of the stator winding in the previous cycle are calculated before the current cycle, the DC current value of any phase of the motor in the current cycle is obtained by sampling and separating the three-phase current of the motor in the current cycle, and the DC voltage value of any phase of the motor in the current cycle is obtained by sampling and separating the three-phase voltage of the motor in the current cycle.

[0038] In step S220, the DC current value of any phase of the motor in the current cycle is taken as the first DC current value, and the DC voltage value of the same phase as the first DC current value in the current cycle is taken as the first DC voltage value. In one embodiment of the present application, the three phases of the motor include phase A, phase B, and phase C, the first DC current value can be the DC current value of phase A, the DC current value of phase B, or the DC current value of phase C, and the first DC voltage value belongs to the same phase as the first DC current value.

[0039] In step S230, the stator winding resistance in the current cycle is calculated according to the first DC current value and the first DC voltage value. In one embodiment of the present application, the calculation formula for the stator winding resistance in the current cycle is as follows:

[0040] R k =U DC (k) / 2I DC (k) Formula (1)

[0041] Among them, R k Indicates the stator winding resistance in the current cycle, U DC (k) represents the first DC voltage value, I DC(k) represents the first direct current value.

[0042] In step S240, the stator winding temperature in the current cycle is evaluated based on the ambient temperature, the stator winding copper loss in the previous cycle, the stator winding evaluation temperature in the previous cycle, and the stator winding resistance in the current cycle. In some embodiments of the present application, the calculation formula for the stator winding temperature in the current cycle includes:

[0043]

[0044] Among them, θ k Indicates the stator winding temperature in the current cycle, θ k-1 Indicates the stator winding temperature in the previous cycle, θ 0 Indicates the ambient temperature, R k Indicates the stator winding resistance in the current cycle, P k-1 It represents the copper loss of stator winding in the previous cycle, Δt represents the time interval of DC voltage signal injection, and τ represents the thermal time constant of the motor.

[0045] In some embodiments of the present application, full consideration is given to the situation in which the electronic winding performs heat exchange with other parts of the motor, and the stator winding temperature in the current cycle is evaluated based on the ambient temperature, the stator winding copper loss in the previous cycle, the evaluated temperature of the stator winding in the previous cycle, and the DC current value and DC voltage value of any phase of the motor in the current cycle. This method is suitable for online evaluation of the stator winding temperature under different working conditions of different types of motors, and improves the accuracy of estimating the stator winding temperature.

[0046] In one embodiment of the present application, before obtaining the DC current value and DC voltage value of any phase of the motor in the current cycle, the motor temperature evaluation method includes:

[0047] The three-phase current of the motor in the current cycle is sampled to obtain a three-phase current sampling signal; and the three-phase voltage of the motor in the current cycle is sampled to obtain a three-phase voltage sampling signal. In one embodiment of the present application, after a DC signal is injected into the three-phase stator circuit of the motor to excite the three-phase stator circuit of the motor, the three-phase current of the motor in the current cycle is sampled through an ADC (Analog-to-Digital Converter) sampling circuit to obtain a three-phase current sampling signal; the three-phase voltage of the motor in the current cycle is sampled through an ADC sampling circuit to obtain a three-phase voltage sampling signal.

[0048] Any one of the three phases is selected as the target phase, the DC current signal and the AC current signal in the target phase current sampling signal are separated to obtain a first DC current value, and the DC voltage signal and the AC voltage signal in the target phase voltage sampling signal are separated to obtain a first DC voltage value. In one embodiment of the present application, the target phase is phase A, phase B or phase C, and the DC current signal and the AC current signal in the target phase current sampling signal are separated by an ADC sampling circuit to obtain a first DC current value; the DC voltage signal and the AC voltage signal in the target phase voltage sampling signal are separated by an ADC sampling circuit to obtain a first DC voltage value.

[0049] In one embodiment of the present application, before sampling the three-phase current of the motor in the current cycle and sampling the three-phase voltage of the motor in the current cycle, the motor temperature evaluation method includes:

[0050] Obtaining the current timing time. In one embodiment of the present application, a timer or the like is used for timing, and it is determined whether the start time of the current cycle has been reached according to the timing time.

[0051] If the current timing moment does not reach the start time of the current cycle, the timing continues until the subsequent moment reaches the start time. In one embodiment of the present application, the start time of the current cycle is obtained by presetting, and the start time of the subsequent cycle can be obtained by presetting, or calculated from the start time of the current cycle and the time interval.

[0052] If the current timing moment reaches the start moment, or the subsequent moment reaches the start moment, a DC signal is injected into the three-phase stator circuit of the motor to perform signal excitation on the three-phase stator circuit of the motor. In one embodiment of the present application, the DC signal is a DC voltage signal, and injecting the DC signal into the three-phase stator circuit of the motor means injecting the DC voltage signal into any phase of the three-phase stator circuit of the motor.

[0053] In one embodiment of the present application, before obtaining the stator winding copper loss in the previous cycle, the motor temperature assessment method includes:

[0054] Obtain the DC current value and DC voltage value of any phase of the motor in the previous cycle. In an embodiment of the present application, the DC current value of any phase of the motor in the previous cycle is obtained by sampling and separating the three-phase current of the motor in the previous cycle, and the DC voltage value of any phase of the motor in the previous cycle is obtained by sampling and separating the three-phase voltage of the motor in the previous cycle.

[0055] The DC current value of any phase of the motor in the previous cycle is used as the second DC current value, and the DC voltage value of the same phase as the second DC current value in the previous cycle is used as the second DC voltage value. In one embodiment of the present application, the three phases of the motor include phase A, phase B, and phase C, the second DC current value can be the DC current value of phase A, the DC current value of phase B, or the DC current value of phase C, and the second DC voltage value belongs to the same phase as the second DC current value.

[0056] The stator winding copper loss in the previous cycle is calculated according to the second DC current value and the second DC voltage value. In one embodiment of the present application, the calculation formula for the stator winding copper loss in the previous cycle includes:

[0057]

[0058] Among them, P k-1 Indicates the stator winding copper loss in the previous cycle, U DC (k-1) represents the second DC voltage value, I DC (k-1) represents the second direct current value.

[0059] Figure 3 is a flow chart of a motor temperature evaluation method shown in another exemplary embodiment of the present application, such as Figure 3 As shown, the motor temperature evaluation method includes: (1) determining whether the current timing moment reaches the signal injection time (for example, the start time of the current cycle); (2) if the current timing moment does not reach the signal injection time, the process ends; (3) if the current timing moment reaches the signal injection time, a DC signal is injected into the three-phase stator circuit of the motor; (4) the three-phase voltage and the three-phase current of the motor are sampled; (5) any one of the three phases is selected as the target phase, and the DC current signal and the AC current signal in the target phase current sampling signal are separated to obtain the first A DC current value is obtained, and the DC voltage signal and the AC voltage signal in the target phase voltage sampling signal are separated to obtain a first DC voltage value; (6) the stator winding resistance in the current cycle is calculated according to formula (1); (7) the stator winding copper loss in the current cycle is calculated according to the first DC current value and the first DC voltage value, and the stator winding copper loss in the current cycle is used to calculate the stator winding temperature in the next cycle; (8) the stator winding temperature in the current cycle is calculated according to formula (2), and the stator winding temperature in the current cycle is also used to calculate the stator winding temperature in the next cycle.

[0060] In one embodiment of the present application, the calculation formula of the stator winding copper loss in the current cycle is as follows:

[0061]

[0062] Among them, P k Indicates the stator winding copper loss in the current cycle, UDC (k) represents the first DC voltage value, I DC (k) represents the first direct current value.

[0063] In one embodiment of the present application, by real-time or periodic acquisition of DC current values ​​and DC voltage values ​​within each cycle, real-time or periodic calculation of stator winding copper loss and stator winding resistance, and real-time or periodic evaluation of stator winding temperature, online evaluation of motor temperature during motor operation is achieved.

[0064] The following describes an apparatus embodiment of the present application, which can be used to execute the motor temperature evaluation method in the above-mentioned embodiment of the present application. For details not disclosed in the apparatus embodiment of the present application, please refer to the above-mentioned embodiment of the motor temperature evaluation method of the present application.

[0065] Figure 4 is a block diagram of a motor temperature evaluation device shown in an exemplary embodiment of the present application. The device can be applied to Figure 1 The implementation environment shown in the figure is specifically configured in the motor controller 102. The device can also be applied to other exemplary implementation environments and specifically configured in other devices. This embodiment does not limit the implementation environment to which the device is applied.

[0066] like Figure 4 As shown, the exemplary motor temperature evaluation device 400 includes:

[0067] The information acquisition module 401 is used to obtain the ambient temperature of the motor, the copper loss of the stator winding in the previous cycle, the temperature of the stator winding in the previous cycle, and the DC current value and DC voltage value of any phase of the motor in the current cycle.

[0068] The information processing module 402 is used to use the DC current value of any phase of the motor in the current cycle as the first DC current value, and use the DC voltage value of the same phase as the first DC current value in the current cycle as the first DC voltage value.

[0069] The resistance calculation module 403 is used to calculate the stator winding resistance in the current cycle according to the first DC current value and the first DC voltage value.

[0070] The temperature evaluation module 404 is used to evaluate the temperature of the stator winding in the current cycle based on the ambient temperature, the copper loss of the stator winding in the previous cycle, the evaluation temperature of the stator winding in the previous cycle and the resistance of the stator winding in the current cycle.

[0071] In one embodiment of the present application, during the operation of the motor, the ambient temperature is acquired in real time through a temperature sensor, etc., the stator winding copper loss in the previous cycle and the stator winding temperature in the previous cycle are calculated before the current cycle, the DC current value of any phase of the motor in the current cycle is obtained by sampling and separating the three-phase current of the motor in the current cycle, and the DC voltage value of any phase of the motor in the current cycle is obtained by sampling and separating the three-phase voltage of the motor in the current cycle.

[0072] In some embodiments of the present application, the three phases of the motor include phase A, phase B, and phase C, the first DC current value may be the DC current value of phase A, the DC current value of phase B, or the DC current value of phase C, and the first DC voltage value and the first DC current value belong to the same phase. The calculation formula for the stator winding resistance in the current cycle is shown in formula (1), and the calculation formula for the stator winding temperature in the current cycle is shown in formula (2).

[0073] In some embodiments of the present application, full consideration is given to the situation in which the electronic winding performs heat exchange with other parts of the motor, and the stator winding temperature in the current cycle is evaluated based on the ambient temperature, the stator winding copper loss in the previous cycle, the evaluated temperature of the stator winding in the previous cycle, and the DC current value and DC voltage value of any phase of the motor in the current cycle. This method is suitable for online evaluation of the stator winding temperature under different working conditions of different types of motors, and improves the accuracy of estimating the stator winding temperature.

[0074] In one embodiment of the present application, the motor temperature evaluation device further includes:

[0075] The signal injection module is used to inject a DC signal into the three-phase stator circuit of the motor when the current timing moment reaches the start moment of the current cycle, so as to perform signal excitation on the three-phase stator circuit of the motor.

[0076] The signal sampling and separation module is used to sample the three-phase current of the motor in the current cycle to obtain a three-phase current sampling signal after the DC signal is injected into the three-phase stator circuit of the motor, and to sample the three-phase voltage of the motor in the current cycle to obtain a three-phase voltage sampling signal; select any one of the three phases as the target phase, separate the DC current signal and the AC current signal in the target phase current sampling signal to obtain a first DC current value, and separate the DC voltage signal and the AC voltage signal in the target phase voltage sampling signal to obtain a first DC voltage value.

[0077] In one embodiment of the present application, the DC signal is a DC voltage signal. Injecting the DC signal into the three-phase stator circuit of the motor means injecting the DC voltage signal into any phase of the three-phase stator circuit of the motor. The target phase is phase A, phase B or phase C. The function of the signal sampling and separation module is realized through the ADC sampling circuit.

[0078] Figure 5 is an architecture diagram of a motor control system shown in an exemplary embodiment of the present application. Figure 5 In the invention, the motor control system includes: an ADC sampling circuit, a digital signal processor (DSP), a data storage device, a pulse width modulation (PWM) driving circuit, a signal injection circuit (i.e., a signal injection module), and a PWM power circuit, wherein the signal injection circuit is used to inject a DC signal into the three-phase stator circuit of the motor when the current timing reaches the start time of the current cycle to perform signal excitation on the three-phase stator circuit of the motor; the ADC sampling circuit is used to sample the three-phase current of the motor in the current cycle to obtain a three-phase current sampling signal after the DC signal is injected into the three-phase stator circuit of the motor, and to sample the three-phase voltage of the motor in the current cycle to obtain a three-phase voltage sampling signal; any one of the three phases is selected as the target phase, the DC current signal and the AC current signal in the target phase current sampling signal are separated to obtain a first DC current value, and the DC voltage signal and the AC voltage signal in the target phase voltage sampling signal are separated to obtain a first DC voltage value; the digital signal processor is used to obtain the ambient temperature of the motor The invention relates to a method for calculating the resistance of the stator winding in the current cycle based on the ambient temperature, the copper loss of the stator winding in the previous cycle, the temperature of the stator winding in the previous cycle, the DC current value and the DC voltage value of any phase of the motor in the current cycle, taking the DC current value of any phase of the motor in the current cycle as the first DC current value, and taking the DC voltage value of the same phase as the first DC current value in the current cycle as the first DC voltage value, calculating the resistance of the stator winding in the current cycle according to the first DC current value and the first DC voltage value, and evaluating the temperature of the stator winding in the current cycle based on the ambient temperature, the copper loss of the stator winding in the previous cycle, the evaluation temperature of the stator winding in the previous cycle and the resistance of the stator winding in the current cycle; the data storage device is used to store the ambient temperature, the copper loss of the stator winding in the previous cycle, the temperature of the stator winding in the previous cycle, the DC current value and the DC voltage value of any phase of the motor in the current cycle; the PWM drive circuit is used to generate a space vector pulse width modulation (SVPWM) signal according to the control instruction of the digital signal processor; and the PWM power circuit controls the motor according to the SVPWM signal.

[0079] In some embodiments of the present application, the ambient temperature of the motor, the copper loss of the stator winding in the previous cycle, the temperature of the stator winding in the previous cycle, the DC current value and the DC voltage value of any phase of the motor in the current cycle are obtained, and the DC current value of any phase of the motor in the current cycle is used as the first DC current value, and the DC voltage value belonging to the same phase as the first DC current value in the current cycle is used as the first DC voltage value. According to the first DC current value and the first DC voltage value, the resistance of the stator winding in the current cycle is calculated. Based on the ambient temperature, the copper loss of the stator winding in the previous cycle, the evaluated temperature of the stator winding in the previous cycle and the resistance of the stator winding in the current cycle, the function of evaluating the temperature of the stator winding in the current cycle can also be implemented by MCU (Microcontroller Unit) and the like, which is not specifically limited here.

[0080] In some embodiments of the present application, the process of a digital signal processor generating control instructions can be implemented with reference to the instruction generation process in the related art, the process of a PWM drive circuit generating a space vector pulse width modulation (SVPWM) signal according to the control instruction of the digital signal processor can be implemented with reference to the SVPWM signal generation process in the related art, and the process of a PWM power circuit controlling a motor according to the SVPWM signal can be implemented with reference to the process of controlling a motor according to the SVPWM signal in the related art, and no specific limitation is made here.

[0081] Figure 6 is a schematic diagram of a signal injection circuit shown in an exemplary embodiment of the present application, such as Figure 6 As shown, the signal injection module includes:

[0082] A first DC power supply, a second DC power supply and a DC signal input module;

[0083] The positive electrode of the first DC power supply is connected to the first end of the first resistor Rs1, the second end of the first resistor Rs1 is connected to the first end of the first inductor Ls1, the second end of the first inductor Ls1 is connected to the first end of the second resistor Rs2, the negative electrode of the first DC power supply is connected to the first end of the third resistor Rs3, the second end of the third resistor Rs3 is connected to the first end of the second inductor Ls2, and the second end of the second inductor Ls2 is connected to the first end of the second resistor Rs2;

[0084] The positive electrode of the second DC power supply is connected to the first end of the fourth resistor Rs3, the second end of the fourth resistor Rs3 is connected to the first end of the third inductor Ls3, the second end of the third inductor Ls3 is connected to the first end of the second resistor Rs2, and the negative electrode of the second DC power supply is connected to the second end of the second resistor Rs2;

[0085] The DC signal input module is connected to the three-phase stator circuit of the motor and is used to input the voltage difference signal between the first end of the first resistor Rs1 and the first end of the third resistor Rs3 as a DC signal into the three-phase stator circuit of the motor.

[0086] In one embodiment of the present application, the first DC power supply and the second DC power supply are the same current source, the resistance value of the first resistor Rs1, the resistance value of the second resistor Rs2, the resistance value of the third resistor Rs3 and the resistance value of the fourth resistor Rs4 are all the same as the stator winding resistance value before the motor is put into use, and the inductance value of the first inductor Ls1, the inductance value of the second inductor Ls2 and the inductance value of the third inductor Ls3 are all the same. The current flowing through the first resistor Rs1 is taken as the DC current value.

[0087] In one embodiment of the present application, a voltmeter is connected between the first end of the first resistor Rs1 and the first end of the third resistor Rs3 to measure the DC voltage U DC The DC current value I is monitored by connecting an ammeter between the positive electrode of the first DC power supply and the first end of the first resistor Rs1. DC Conduct monitoring.

[0088] In some embodiments of the present application, according to the circuit structure of the signal injection module, formula (1), formula (3) and formula (4) can be deduced, and based on formula (1), formula (3), formula (4) and the second-order thermal model of the motor, formula (2) is derived. The derivation process of formula (1), formula (3), formula (4) and formula (2) is not limited herein.

[0089] In some embodiments of the present application, the first resistor Rs1, the third resistor Rs3 and the fourth resistor Rs4 in the three phases are connected in parallel, and an inductor is connected in series in each phase, wherein the A phase and the B phase are excited by the first DC power supply, and the C phase is excited by the second DC power supply. After the first DC power supply and the second DC power supply generate signal excitation, the three-phase current and the three-phase voltage of the motor in the current cycle are sampled, and the sampled signals are separated and calculated to measure the stator winding resistance, stator winding copper loss and stator winding temperature; the second DC power supply excites the C phase with the same current as the first DC power supply through the neutral point N to maintain the thermal symmetry of each phase, and the three phases are connected in parallel, which is conducive to ensuring that the three phases are heated evenly. The motor is heated from the ambient temperature θ 0 When operation starts, the three phases are connected in parallel for DC excitation, which produces a measurable change in the stator winding temperature.

[0090] It should be noted that the motor temperature evaluation device provided in the above embodiment and the motor temperature evaluation method provided in the above embodiment belong to the same concept, wherein the specific manner in which each module and unit performs the operation has been described in detail in the method embodiment, and will not be repeated here. In practical applications, the motor temperature evaluation device provided in the above embodiment can distribute the above functions to different functional modules as needed, that is, divide the internal structure of the device into different functional modules to complete all or part of the functions described above, and this is not limited here.

[0091] An embodiment of the present application also provides a motor controller, comprising: one or more processors; a storage device for storing one or more programs, when the one or more programs are executed by one or more processors, the motor controller implements the motor temperature assessment method provided in the above-mentioned embodiments.

[0092] Figure 7 The structure diagram of a computer system suitable for implementing the motor controller of the embodiment of the present application is shown. It should be noted that: Figure 7 The computer system 700 of the motor controller shown is only an example and should not bring any limitation to the functions and scope of use of the embodiments of the present application.

[0093] like Figure 7 As shown, the computer system 700 includes a central processing unit (CPU) 701, which can perform various appropriate actions and processes according to the program stored in the read-only memory (ROM) 702 or the program loaded from the storage part 708 to the random access memory (RAM) 703, such as executing the method in the above embodiment. In the RAM 703, various programs and data required for system operation are also stored. The CPU 701, the ROM 702 and the RAM 703 are connected to each other through the bus 704. The input / output (I / O) interface 705 is also connected to the bus 704.

[0094] The following components are connected to the I / O interface 705: an input section 706 including a keyboard, a mouse, etc.; an output section 707 including a cathode ray tube (CRT), a liquid crystal display (LCD), etc., and a speaker, etc.; a storage section 708 including a hard disk, etc.; and a communication section 709 including a network interface card such as a LAN (Local Area Network) card, a modem, etc. The communication section 709 performs communication processing via a network such as the Internet. A drive 710 is also connected to the I / O interface 705 as needed. A removable medium 711, such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc., is installed on the drive 710 as needed so that a computer program read therefrom is installed into the storage section 708 as needed.

[0095] In particular, according to an embodiment of the present application, the process described above with reference to the flowchart can be implemented as a computer software program. For example, an embodiment of the present application includes a computer program product, which includes a computer program carried on a computer-readable medium, and the computer program includes a computer program for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from a network through a communication section 709, and / or installed from a removable medium 711. When the computer program is executed by a central processing unit (CPU) 701, various functions defined in the system of the present application are executed.

[0096] It should be noted that the computer-readable medium shown in the embodiment of the present application can be a computer-readable signal medium or a computer-readable storage medium or any combination of the above two. The computer-readable storage medium can be, for example, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or device, or any combination of the above. More specific examples of computer-readable storage media can include, but are not limited to: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM), a flash memory, an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In the present application, a computer-readable signal medium may include a data signal propagated in a baseband or as part of a carrier wave, wherein a computer-readable computer program is carried. This propagated data signal can take a variety of forms, including but not limited to an electromagnetic signal, an optical signal, or any suitable combination of the above. A computer-readable signal medium may also be any computer-readable medium other than a computer-readable storage medium, which may send, propagate or transmit a program for use by or in conjunction with an instruction execution system, apparatus or device. A computer program contained on a computer-readable medium may be transmitted using any appropriate medium, including but not limited to: wireless, wired, etc., or any suitable combination of the above.

[0097] The flowchart and block diagram in the accompanying drawings illustrate the possible architecture, functions and operations of the system, method and computer program product according to various embodiments of the present application. Wherein, each box in the flowchart or block diagram can represent a module, a program segment, or a part of the code, and the above-mentioned module, program segment, or a part of the code contains one or more executable instructions for realizing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram or flowchart, and the combination of boxes in the block diagram or flowchart can be implemented with a dedicated hardware-based system that performs a specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0098] The units involved in the embodiments described in this application may be implemented by software or hardware, and the units described may also be set in a processor. The names of these units do not, in some cases, constitute limitations on the units themselves.

[0099] Another aspect of the present application further provides a computer-readable storage medium having computer-readable instructions stored thereon, which, when executed by a processor of a computer, causes the computer to execute the motor temperature evaluation method provided in the above-mentioned embodiments. The computer-readable storage medium may be included in the motor controller described in the above-mentioned embodiments, or may exist independently without being assembled into the motor controller.

[0100] It should be noted that, although several modules or units of the equipment for action execution are mentioned in the above detailed description, this division is not mandatory. In fact, according to the embodiments of the present application, the features and functions of two or more modules or units described above can be embodied in one module or unit. On the contrary, the features and functions of one module or unit described above can be further divided into being embodied by multiple modules or units.

[0101] Through the description of the above implementation methods, it is easy for those skilled in the art to understand that the example implementation methods described here can be implemented by software or by combining software with necessary hardware. Therefore, the technical solution according to the implementation methods of the present application can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (which can be a CD-ROM, a USB flash drive, a mobile hard disk, etc.) or on a network, and includes several instructions to enable a computing device (which can be a personal computer, a server, a touch terminal, or a network device, etc.) to execute the method according to the implementation methods of the present application.

[0102] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the embodiments disclosed herein. The present application is intended to cover any variations, uses or adaptations of the present application, which follow the general principles of the present application and include common knowledge or customary technical means in the art that are not disclosed in the present application.

[0103] It should be understood that the above content is only a preferred exemplary embodiment of the present application and is not intended to limit the implementation scheme of the present application. Ordinary technicians in this field can easily make corresponding changes or modifications based on the main concept and spirit of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection required by the claims.

Claims

1. A method for evaluating motor temperature, characterized in that: The method comprises: Obtain the ambient temperature of the motor, the copper loss of the stator winding in the previous cycle, the temperature of the stator winding in the previous cycle, and the DC current and DC voltage values ​​of any phase of the motor in the current cycle; Taking a DC current value of any phase of the motor in the current cycle as a first DC current value, and taking a DC voltage value of the same phase as the first DC current value in the current cycle as a first DC voltage value; Calculating a stator winding resistance in a current cycle according to the first DC current value and the first DC voltage value; The stator winding temperature in the current cycle is evaluated based on the ambient temperature, the stator winding copper loss in the previous cycle, the stator winding evaluation temperature in the previous cycle and the stator winding resistance in the current cycle.

2. The motor temperature evaluation method according to claim 1, characterized in that: Before obtaining the DC current value and DC voltage value of any phase of the motor in the current cycle, the method includes: Sampling the three-phase current of the motor in the current cycle to obtain a three-phase current sampling signal; and sampling the three-phase voltage of the motor in the current cycle to obtain a three-phase voltage sampling signal; Any one of the three phases is selected as the target phase, the DC current signal and the AC current signal in the target phase current sampling signal are separated to obtain the first DC current value, and the DC voltage signal and the AC voltage signal in the target phase voltage sampling signal are separated to obtain the first DC voltage value.

3. The motor temperature evaluation method according to claim 2, characterized in that: Before sampling the three-phase current of the motor in the current cycle and sampling the three-phase voltage of the motor in the current cycle, the method includes: Get the current timing moment; If the current timing moment has not reached the start time of the current cycle, then continue timing until the subsequent moment reaches the start time; If the current timing moment reaches the start moment, or the subsequent moment reaches the start moment, a DC signal is injected into the three-phase stator circuit of the motor to perform signal excitation on the three-phase stator circuit of the motor.

4. The motor temperature evaluation method according to any one of claims 1 to 3, characterized in that: Before obtaining the stator winding copper loss in the previous cycle, the method includes: Obtaining the DC current value and DC voltage value of any phase of the motor in the previous cycle; Using a DC current value of any phase of the motor in the previous cycle as a second DC current value, and using a DC voltage value of the same phase as the second DC current value in the previous cycle as a second DC voltage value; The stator winding copper loss in the previous cycle is calculated according to the second DC current value and the second DC voltage value.

5. The motor temperature evaluation method according to claim 4, characterized in that: The calculation formula for the stator winding copper loss in the previous cycle includes: Among them, P k-1 Indicates the stator winding copper loss in the previous cycle, U DC (k-1) represents the second DC voltage value, I DC (k-1) represents the second direct current value.

6. The motor temperature evaluation method according to any one of claims 1 to 3, characterized in that: The calculation formula of the stator winding resistance in the current cycle includes: R k =U DC (k) / 2I DC (k), Among them, R k Indicates the stator winding resistance in the current cycle, U DC (k) represents the first DC voltage value, I DC (k) represents the first direct current value.

7. The motor temperature evaluation method according to any one of claims 1 to 3, characterized in that: The calculation formula of the stator winding temperature in the current cycle includes: Among them, θ k Indicates the stator winding temperature in the current cycle, θ k-1 represents the stator winding temperature in the previous cycle, θ0 represents the ambient temperature, R k Indicates the stator winding resistance in the current cycle, P k-1 It represents the copper loss of stator winding in the previous cycle, Δt represents the time interval of DC voltage signal injection, and τ represents the thermal time constant of the motor.

8. A motor temperature evaluation device, characterized in that: The device comprises: The information acquisition module is used to obtain the ambient temperature of the motor, the copper loss of the stator winding in the previous cycle, the temperature of the stator winding in the previous cycle, and the DC current value and DC voltage value of any phase of the motor in the current cycle; an information processing module, configured to use a DC current value of any phase of the motor in the current cycle as a first DC current value, and use a DC voltage value of the same phase as the first DC current value in the current cycle as a first DC voltage value; a resistance calculation module, used to calculate the stator winding resistance in a current cycle according to the first DC current value and the first DC voltage value; The temperature evaluation module is used to evaluate the temperature of the stator winding in the current cycle based on the ambient temperature, the copper loss of the stator winding in the previous cycle, the evaluation temperature of the stator winding in the previous cycle and the resistance of the stator winding in the current cycle.

9. The motor temperature evaluation device according to claim 8, characterized in that: The device also includes: A signal injection module, used for injecting a DC signal into a three-phase stator circuit of the motor when the current timing reaches the start time of the current cycle, so as to perform signal excitation on the three-phase stator circuit of the motor; A signal sampling and separation module is used to sample the three-phase current of the motor in the current cycle to obtain a three-phase current sampling signal, and to sample the three-phase voltage of the motor in the current cycle to obtain a three-phase voltage sampling signal after the DC signal is injected into the three-phase stator circuit of the motor; select any one of the three phases as the target phase, separate the DC current signal and the AC current signal in the target phase current sampling signal to obtain the first DC current value, and separate the DC voltage signal and the AC voltage signal in the target phase voltage sampling signal to obtain the first DC voltage value.

10. The motor temperature evaluation device according to claim 9, characterized in that: The signal injection module comprises: A first DC power supply, a second DC power supply and a DC signal input module; The positive electrode of the first DC power supply is connected to the first end of the first resistor, the second end of the first resistor is connected to the first end of the first inductor, the second end of the first inductor is connected to the first end of the second resistor, the negative electrode of the first DC power supply is connected to the first end of the third resistor, the second end of the third resistor is connected to the first end of the second inductor, and the second end of the second inductor is connected to the first end of the second resistor; The positive electrode of the second DC power supply is connected to the first end of the fourth resistor, the second end of the fourth resistor is connected to the first end of the third inductor, the second end of the third inductor is connected to the first end of the second resistor, and the negative electrode of the second DC power supply is connected to the second end of the second resistor; The DC signal input module is connected to the three-phase stator circuit of the motor, and is used to input the voltage difference signal between the first end of the first resistor and the first end of the third resistor as the DC signal into the three-phase stator circuit of the motor.

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