Method and device for low temperature operation of a motor controller, and motor controller

Abstract

The application discloses a kind of motor controller low temperature operation method, device and motor controller, when the working environment temperature of motor controller is lower than preset temperature limit value, the junction temperature of power device of motor controller is estimated using the junction temperature estimation model established in advance, according to the junction temperature of power device and current bus voltage, the current torque limit value of motor controller is determined, the output torque value of motor controller is controlled in torque limit value, and the working speed of motor controller is controlled in speed limit value.The application determines the current torque limit value of motor controller based on the two dimensions of the junction temperature of power device and current bus voltage, by controlling the output torque value of motor controller in torque limit value, and controlling the working speed of motor controller in speed limit value, the voltage stress of power device is inhibited not to exceed the withstand voltage range, so as to ensure the working stability of motor controller.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of motor controller, more particularly, to a method and device for low-temperature operation of a motor controller and the motor controller. BACKGROUND

[0002] A motor controller is an integrated circuit used to control a motor to work in a set direction, speed, angle and response time. At present, the voltage spikes generated by the power device of the motor controller under different temperature conditions and the same working current are different, and show a negative temperature characteristic. Under normal temperature conditions, the voltage spikes generated by the power device under normal working and short circuit are small. However, under low temperature conditions below-10℃, the voltage spikes generated by the power device under normal working and short circuit will increase with the decrease of temperature. However, the withstand voltage level of the power device is a positive temperature characteristic, so the power device is prone to voltage stress exceeding the standard under low temperature conditions. If the voltage stress exceeding the standard of the power device is not handled in time, the service life of the motor controller will be shortened, and the motor controller may even be damaged under low temperature short circuit. SUMMARY

[0003] Therefore, the present application discloses a method and device for low-temperature operation of a motor controller and the motor controller to realize the suppression of power device voltage stress within the withstand voltage range and ensure the working stability of the motor controller.

[0004] A method for low-temperature operation of a motor controller, comprising:

[0005] When the working environment temperature of the motor controller is lower than a preset temperature limit value, the junction temperature of the power device of the motor controller is estimated by using a pre-established junction temperature estimation model, wherein the junction temperature estimation model is a thermal capacity and thermal resistance model of the power device of the motor controller and its peripheral circuit;

[0006] The current torque limit value of the motor controller is determined according to the junction temperature of the power device and the current bus voltage;

[0007] The output torque value of the motor controller is controlled within the current torque limit value, and the working rotational speed of the motor controller is controlled within a rotational speed limit value, wherein the rotational speed limit value is determined based on a maximum torque current ratio interval.

[0008] Optionally, the determination of the current torque limit value of the motor controller according to the junction temperature of the power device and the current bus voltage comprises:

[0009] The current limit value is determined based on the junction temperature of the power device and the current bus voltage;

[0010] The current limit value corresponding to the current bus voltage and the power device junction temperature is determined based on a correspondence relationship between motor current and torque limit values in a maximum torque current ratio interval.

[0011] Optionally, the current limit value is determined based on the power device junction temperature and the current bus voltage, including:

[0012] The current limit value corresponding to the power device junction temperature and the current bus voltage is found from a correspondence relationship among the measured current peak, the measured power device junction temperature, and the measured bus voltage.

[0013] Optionally, the correspondence relationship between motor current and torque limit values in the maximum torque current ratio interval is obtained by piecewise linear or polynomial fitting.

[0014] Optionally, the method further includes:

[0015] When the operating environment temperature of the motor controller rises to be greater than the preset temperature limit, the motor controller is controlled to restore to a normal output torque value and operating speed.

[0016] Optionally, the junction temperature estimation model is determined based on power device input power, power device thermal resistance, and power device thermal capacity.

[0017] A device for low-temperature operation of a motor controller, including:

[0018] An estimation unit configured to, when an operating environment temperature of the motor controller is lower than a preset temperature limit, estimate a power device junction temperature of the motor controller using a pre-established junction temperature estimation model, wherein the junction temperature estimation model is a thermal capacity and thermal resistance model of a power device and its peripheral circuit of the motor controller;

[0019] A torque limit value determination unit configured to determine a current torque limit value of the motor controller based on the power device junction temperature and a current bus voltage;

[0020] A control unit configured to control an output torque value of the motor controller to be within the current torque limit value and control an operating speed of the motor controller to be within a speed limit value, wherein the speed limit value is determined based on a maximum torque current ratio interval.

[0021] Optionally, the torque limit value determination unit includes:

[0022] A current limit value determination sub-unit configured to determine a current limit value based on the power device junction temperature and the current bus voltage;

[0023] A torque limit value determination sub-unit configured to determine the current torque limit value corresponding to the current limit value based on a correspondence relationship between motor current and torque limit values in a maximum torque current ratio interval.

[0024] Optionally, the current limit value determination sub-unit is specifically configured to:

[0025] The current limit value corresponding to the power device junction temperature and the current bus voltage is found from the correspondence between the measured current peak, the measured power device junction temperature and the measured bus voltage.

[0026] Optionally, the method further comprises:

[0027] The recovery unit is configured to control the motor controller to recover to a normal output torque value and a working speed when the working environment temperature of the motor controller rises to be greater than the preset temperature limit.

[0028] Optionally, the junction temperature estimation model is determined based on power device input power, power device thermal resistance and power device thermal capacity.

[0029] A motor controller, comprising a memory and a processor;

[0030] The memory is configured to store at least one instruction;

[0031] The processor is configured to execute the at least one instruction to implement the method for low-temperature operation of the motor controller.

[0032] From the above technical solutions, the present application discloses a method, device and motor controller for low-temperature operation of a motor controller. When the working environment temperature of the motor controller is lower than a preset temperature limit, the junction temperature of the power device of the motor controller is estimated by using a pre-established junction temperature estimation model. The current torque limit value of the motor controller is determined according to the power device junction temperature and the current bus voltage. The output torque value of the motor controller is controlled within the torque limit value, and the working speed of the motor controller is controlled within the speed limit value. The present application determines the current torque limit value of the motor controller based on two dimensions of the power device junction temperature and the current bus voltage. By controlling the output torque value of the motor controller within the torque limit value and the working speed of the motor controller within the speed limit value, the voltage stress of the power device is inhibited from exceeding the withstand voltage range, thereby ensuring the working stability of the motor controller. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor based on the disclosed drawings.

[0034] Figure 1A flow chart of a method for low-temperature operation of a motor controller according to an embodiment of the present application is disclosed.

[0035] Figure 2 A simplified junction temperature estimation model based on thermal temperature and thermal resistance according to an embodiment of the present application is disclosed.

[0036] Figure 3 A flow chart of a method for determining a current torque limit value of a motor controller according to an embodiment of the present application is disclosed.

[0037] Figure 4 A correspondence diagram of a measured current spike, a measured power device junction temperature and a measured bus voltage according to an embodiment of the present application is disclosed.

[0038] Figure 5 A correspondence between a motor current and a torque limit value of a certain type of motor according to an embodiment of the present application is disclosed.

[0039] Figure 6 A field weakening region working curve of a certain type of motor according to an embodiment of the present application is disclosed.

[0040] Figure 7 A comparison diagram of an original current value and a current value after torque limiting according to an embodiment of the present application is disclosed.

[0041] Figure 8 A comparison diagram of a motor current in the present application and a motor current in a conventional scheme in a low-temperature operation interval at -40℃ according to an embodiment of the present application is disclosed.

[0042] Figure 9 A structural diagram of a device for low-temperature operation of a motor controller according to an embodiment of the present application is disclosed.

[0043] Figure 10 A structural diagram of a motor controller according to an embodiment of the present application is disclosed. DETAILED DESCRIPTION

[0044] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without any creative work fall within the scope of protection of the present application.

[0045] The embodiment of the application discloses a motor controller low-temperature operation method and device and a motor controller, when the working environment temperature of the motor controller is lower than a preset temperature limit value, the junction temperature of the power device of the motor controller is estimated by using a pre-established junction temperature estimation model, the current torque limit value of the motor controller is determined according to the power device junction temperature and the current bus voltage, the output torque value of the motor controller is controlled within the torque limit value, and the working speed of the motor controller is controlled within the speed limit value. The current torque limit value of the motor controller is determined based on the power device junction temperature and the current bus voltage, the output torque value of the motor controller is controlled within the torque limit value, and the working speed of the motor controller is controlled within the speed limit value, so that the voltage stress of the power device is inhibited from exceeding the withstand voltage range, thereby ensuring the working stability of the motor controller.

[0046] Referring to Figure 1 , the embodiment of the application discloses a motor controller low-temperature operation method flow chart, and the method comprises the following steps:

[0047] Step S101, when the working environment temperature of the motor controller is lower than a preset temperature limit value, the junction temperature of the power device of the motor controller is estimated by using a pre-established junction temperature estimation model.

[0048] The value of the preset temperature limit is determined according to actual needs, for example, -10 DEG C, and the application does not limit this.

[0049] The motor controller in the embodiment is mainly a permanent magnet synchronous motor controller.

[0050] The junction temperature estimation model in the embodiment is a thermal capacity and thermal resistance model of the power device and the peripheral circuit of the motor controller, and the junction temperature estimation model can accurately estimate the junction temperature of the power device of the motor controller.

[0051] The simplified junction temperature estimation model (Foster thermal model) obtained based on the thermal capacity and the thermal resistance is as shown in Figure 2 Each power device can be equivalent to two parts of a switching device and a diode. Figure 2 The junction temperature estimation model as shown in the figure is composed of four parts, the first part is composed of R T_H , C T_H and P T_H , the second part is composed of R D_H , C D_H and P D_H , the third part is composed of R T_L , C T_L and P T_L , and the fourth part is composed of R D_L , C D_L and P D_L .

[0052] R T_H represents the switching device thermal resistance of the current power device, C T_H represents the switching device thermal capacitance of the current power device, P T_H represents the equivalent power device power, R D_H represents the diode thermal resistance of the current power device, C D_H represents the diode thermal capacitance of the current power device, P D_H represents the diode power of the current power device.

[0053] R T_L represents the switching device conduction thermal resistance of the adjacent power device, C T_L represents the switching device conduction thermal capacitance of the adjacent power device, P T_L represents the power of the adjacent power device, R D_L represents the diode conduction thermal resistance of the adjacent power device, C D_L represents the diode conduction thermal capacitance of the adjacent power device, P D_L represents the diode power of the adjacent power device.

[0054] The calculation formula of the power device input power is as follows:

[0055]

[0056] In the formula, C represents the power device thermal capacitance, T d represents the power device temperature, R represents the thermal resistance, P in represents the power device input power, P in = U dc *I, U dc represents the bus voltage, and I represents the bus current.

[0057] According to formula (1), the power device junction temperature can be estimated under the given input power.

[0058] In the present application, the junction temperature estimation model is determined based on the power device input power, the power device thermal resistance, and the power device thermal capacitance.

[0059] Specifically, the calculation formula of the power device junction temperature is shown in formula (2), and formula (2) is as follows:

[0060]

[0061] In the formula, T dd represents the power device junction temperature, P in represents the power device input power, details are shown in formula (1), R represents the power device thermal resistance, C represents the power device thermal capacitance, and t represents time.

[0062] Step S102, determining a current torque limit value of the motor controller according to the power device junction temperature and a current bus voltage;

[0063] Step S103, controlling the output torque value of the motor controller within the torque limit value, and controlling the working speed of the motor controller within a speed limit value.

[0064] The speed limit value is determined based on a maximum torque per ampere (MTPA). The maximum torque per ampere refers to that the maximum torque Is*Is=id*id+iq*iq is generated under the same current amplitude Is by id and iq distribution. The process of determining the speed limit value based on the MTPA can refer to the existing mature scheme, and will not be described here.

[0065] When the motor controller operates at low temperature, in addition to limiting the output torque of the motor, the speed limit value of the motor also needs to be considered.

[0066] Therefore, by controlling the output torque value of the motor controller within the torque limit value, and controlling the working speed of the motor controller within the speed limit value, the voltage stress of the power device is inhibited from exceeding the voltage range.

[0067] In conclusion, the present application discloses a method for low-temperature operation of a motor controller. When the working environment temperature of the motor controller is lower than a preset temperature limit value, the junction temperature of the power device of the motor controller is estimated by using a pre-established junction temperature estimation model. The current torque limit value of the motor controller is determined according to the power device junction temperature and the current bus voltage. The output torque value of the motor controller is controlled within the torque limit value, and the working speed of the motor controller is controlled within the speed limit value. The present application determines the current torque limit value of the motor controller based on two dimensions of the power device junction temperature and the current bus voltage. By controlling the output torque value of the motor controller within the torque limit value, and controlling the working speed of the motor controller within the speed limit value, the voltage stress of the power device is inhibited from exceeding the voltage range, thereby ensuring the working stability of the motor controller.

[0068] To further optimize the above-mentioned embodiment, referring to Figure 3 The determination method flow chart of the current torque limit value of the motor controller disclosed by the embodiment of the present application, that is, step S102, can specifically include:

[0069] Step S201, determining a current torque limit value of the motor controller according to the power device junction temperature and a current bus voltage;

[0070] Specifically, the current limit value corresponding to the power device junction temperature and the current bus voltage is found from the corresponding relationship among the measured current peak, the measured power device junction temperature and the measured bus voltage.

[0071] By studying the low-temperature characteristics of power devices, it was found that the current spikes of power devices at low temperatures are not only negatively correlated with temperature, but also positively correlated with the actual bus voltage. Therefore, this invention pre-measured the current spikes, the junction temperature of the power device, and the bus voltage, and found the current limit values ​​corresponding to the junction temperature of the power device and the current bus voltage from the correspondence between the measured current spikes, the measured junction temperature of the power device, and the measured bus voltage.

[0072] The correspondence between measured current spikes, measured power device junction temperatures, and measured bus voltages can be found in [reference needed]. Figure 4 As shown.

[0073] Step S202: Based on the correspondence between the motor current and torque limit values ​​in the maximum torque-current ratio range, determine the current torque limit value corresponding to the current limit value.

[0074] In this embodiment, the correspondence between the motor current and torque limit value in the maximum torque-current ratio range is obtained by piecewise linear or polynomial fitting.

[0075] See details Figure 5 The diagram shows the correspondence between the current and torque limit values ​​of a certain type of motor. Figure 5 The motor current in the value corresponds to the current limit value calculated in step S201. Figure 5 As can be seen, the motor current and torque limit value have a near-linear relationship. Therefore, in practical applications, piecewise or polynomial fitting can be used to obtain the correspondence between the motor current and torque limit value in the range of maximum torque-current ratio.

[0076] In summary, this invention determines the current limit value based on the junction temperature of the power device and the current bus voltage, then further determines the current torque limit value based on the MTPA characteristics, and finally limits the operating torque of the motor controller within the current torque limit value. This invention converts the current limit value into a torque limit value, no longer directly limiting the current value, but indirectly reducing the current limit value by reducing the output torque of the motor controller. This suppresses the voltage stress on the power device from exceeding its withstand voltage range, ensuring the normal output of active power by the motor.

[0077] The speed limit value is determined based on the process of determining the maximum torque-to-current ratio range. Figure 6 As shown.

[0078] The following is combined with Figure 6 The diagram shown illustrates the field weakening zone operation curve of a certain type of motor, explaining the process of limiting the motor's operating speed. Figure 6 in i d and i q These are the orthogonal d-axis and q-axis currents, respectively. Their resultant quantity is a current vector.

[0079] A point is the intersection of the current limit circle and MTPA, B point is the intersection of the voltage limit ellipse and MTPV(Maximum Torque Per Voltage).

[0080] Where the current limit circle expression as follows:

[0081]

[0082] In the formula, The limit output capability of permanent magnet synchronous motor controller represented by the formula, is limited by hardware design.

[0083] From the formula, the output i Figure 6 of permanent magnet synchronous motor controller must be limited within the current limit circle, if exceeding the current limit circle, the hardware threshold will be exceeded, which will cause the machine to be destroyed and other serious consequences. d and i q must be limited within the current limit circle, if exceeding the current limit circle, the hardware threshold will be exceeded, which will cause the machine to be destroyed and other serious consequences. d and i q In addition to being limited by the current limit circle, it is also limited by the voltage equation of the permanent magnet synchronous motor, the expression of which is as follows:

[0084] (L q i q ) 2 +(L d i d +ψ f ) 2 =(u lim / ω) 2 (4);

[0085] In the formula, L q represents the d-axis inductance of the motor, L d represents the q-axis inductance of the motor, ψ f represents the flux of the motor, L q , L d , ψ f are constants, u lim represents the bus voltage input, generally a fixed value, and ω is the motor speed.

[0086] Formula (4) determines the boundary of the maximum value of d-axis current and q-axis current under the condition of constant motor speed as an ellipse, i.e. Figure 6 the voltage limit ellipse in the formula.

[0087] From formula (4) and Figure 6 It can be seen that as the motor speed increases, the boundary of the curve is gradually shrinking (i.e. the voltage limit ellipse is gradually getting smaller), which changes from the large ellipse corresponding to A to the small ellipse corresponding to B. In the case of small ellipse corresponding to B, id and i q The current distribution can no longer follow the MTPA line. It can only be distributed within the elliptical curve corresponding to point B. The current vector at point B, i... s The relationship between amplitude and torque deviates from the MTPA curve, therefore the relationship between current value and torque limit does not satisfy the condition. Figure 5 The curve shown. To ensure that it meets the requirements... Figure 5 The curve shown indicates that the motor's operating speed must be limited to below point A. Therefore, point A is the operating speed limit at this point.

[0088] When the motor controller is working, it refers to the torque limit value and the speed limit value to ensure that the output torque does not exceed the torque limit value and the motor speed does not exceed the speed limit value.

[0089] This invention limits the actual operating current of the motor controller by restricting the output torque and operating speed of the motor. (See also...) Figure 7 The diagram showing the comparison between the original current value and the current value after torque limiting is as follows: Figure 7 As can be seen, the original current value is very close to the current value after torque limiting, and in certain voltage ranges, the current value after torque limiting is less than the original current value. The reduced current value ensures that the voltage stress generated during turn-off does not exceed the withstand voltage.

[0090] This invention calculates the current limit value from two dimensions: the junction temperature of the power device and the bus voltage. Compared to the traditional approach that limits the motor current to a minimum value at the current temperature, this invention broadens the operating range of the power device. See details... Figure 8 The diagram shows a comparison of the motor current in this invention and the motor current in the conventional solution within the low-temperature operating range of -40℃. From... Figure 8 As can be seen, the present invention enables the motor controller to still output a large power at low temperatures, thereby ensuring the low-temperature response of the motor controller.

[0091] In order to ensure that the motor controller operates within the MTPA range, this invention limits the operating speed range of the current controller. However, when the ambient temperature of the motor controller rises, the output torque value of the motor controller will return to normal. At this time, the limitation on the motor speed can be removed.

[0092] Therefore, to further optimize the above embodiments, the method for low-temperature operation of the motor controller may further include:

[0093] When the ambient temperature of the motor controller rises above the preset temperature limit, the motor controller will be restored to its normal output torque value and operating speed.

[0094] The preset temperature limit is determined according to actual needs, for example, -10 DEG C, and the application does not limit this.

[0095] Corresponding to the method embodiment, the application further discloses a device for low-temperature operation of a motor controller.

[0096] Referring to Figure 9 , the device for low-temperature operation of a motor controller disclosed in the embodiment of the application has the structure as shown in the figure, and the device comprises:

[0097] An estimation unit 301 is configured to, when the working environment temperature of the motor controller is lower than a preset temperature limit, estimate the junction temperature of the power device of the motor controller by using a pre-established junction temperature estimation model, wherein the junction temperature estimation model is a thermal capacity and thermal resistance model of the power device of the motor controller and the peripheral circuit thereof.

[0098] The preset temperature limit is determined according to actual needs, for example, -10 DEG C, and the application does not limit this.

[0099] The motor controller in the embodiment is mainly a permanent magnet synchronous motor controller.

[0100] The junction temperature estimation model in the embodiment is a thermal capacity and thermal resistance model of the power device of the motor controller and the peripheral circuit thereof, and the junction temperature estimation model can be used to accurately estimate the junction temperature of the power device of the motor controller.

[0101] The simplified junction temperature estimation model (Foster thermal model) obtained based on the thermal capacity and the thermal resistance is as shown in Figure 2 .

[0102] A torque limit value determination unit 302 is configured to determine the current torque limit value of the motor controller according to the junction temperature of the power device and the current bus voltage.

[0103] A control unit 303 is configured to control the output torque value of the motor controller to be within the current torque limit value and control the working rotating speed of the motor controller to be within a rotating speed limit value, wherein the rotating speed limit value is determined based on a maximum torque current ratio interval.

[0104] The rotating speed limit value is determined based on MTPA, and the specific process can be referred to the existing mature scheme, and thus will not be described here.

[0105] When the motor controller operates at low temperature, in addition to limiting the output torque of the motor, the rotating speed limit value of the motor also needs to be considered.

[0106] Therefore, the application controls the output torque value of the motor controller within the torque limit value and controls the working speed of the motor controller within the speed limit value, so that the voltage stress of the power device is inhibited from exceeding the voltage range.

[0107] In conclusion, the application discloses a device for low-temperature operation of a motor controller, which estimates the junction temperature of the power device of the motor controller by using a pre-established junction temperature estimation model when the working environment temperature of the motor controller is lower than a preset temperature limit value, determines the current torque limit value of the motor controller according to the junction temperature of the power device and the current bus voltage, controls the output torque value of the motor controller within the torque limit value, and controls the working speed of the motor controller within the speed limit value. The application determines the current torque limit value of the motor controller based on two dimensions of the junction temperature of the power device and the current bus voltage, controls the output torque value of the motor controller within the torque limit value, and controls the working speed of the motor controller within the speed limit value, so that the voltage stress of the power device is inhibited from exceeding the voltage range, thereby ensuring the working stability of the motor controller.

[0108] To further optimize the above-mentioned embodiment, the torque limit value determination unit 302 can include:

[0109] a current limit value determination subunit configured to determine a current limit value based on the junction temperature of the power device and the current bus voltage;

[0110] The current limit value determination subunit is specifically configured to:

[0111] find the current limit value corresponding to the junction temperature of the power device and the current bus voltage from the correspondence among the measured current peak, the measured junction temperature of the power device and the measured bus voltage.

[0112] It is found through the study of the low-temperature characteristics of the power device that the current peak of the power device at low temperature is not only negatively correlated with the temperature, but also positively correlated with the actual bus voltage. Therefore, the application measures the current peak, the junction temperature of the power device and the bus voltage in advance, and finds the current limit value corresponding to the junction temperature of the power device and the current bus voltage from the correspondence among the measured current peak, the measured junction temperature of the power device and the measured bus voltage.

[0113] The correspondence among the measured current peak, the measured junction temperature of the power device and the measured bus voltage can be seen from Figure 4 .

[0114] The torque limit value determination subunit is configured to determine the current torque limit value corresponding to the current limit value based on the correspondence between the motor current of the maximum torque current ratio interval and the torque limit value.

[0115] In this embodiment, the correspondence between the motor current of the maximum torque current ratio interval and the torque limit value is obtained by piecewise linear or polynomial fitting.

[0116] As can be seen, after the current limit value is determined based on the junction temperature of the power device and the current bus voltage, the current torque limit value is further determined according to the MTPA characteristic, and the working torque of the motor controller is limited within the current torque limit value. The current limit value is converted into the torque limit value, and the current value is no longer directly limited, but the output torque of the motor controller is reduced to indirectly reduce the current limit value, so that the voltage stress of the power device is suppressed to be within the withstand voltage range, and the normal output of the active power of the motor is ensured.

[0117] In order to ensure that the motor controller works in the MTPA range, the working speed range of the current controller is limited, but when the working environment temperature of the motor controller rises, the output torque value of the motor controller will return to normal, at this time, the limitation of the motor speed can be cancelled.

[0118] Therefore, the device for low-temperature operation of the motor controller can further include:

[0119] When the working environment temperature of the motor controller rises to be greater than the preset temperature limit, the motor controller is controlled to return to the normal output torque value and the working speed.

[0120] The value of the preset temperature limit is determined according to actual needs, such as-10℃, which is not limited in the present application.

[0121] It should be particularly noted that the specific working principles of each component in the device embodiment are described in the corresponding part of the method embodiment, which will not be repeated here.

[0122] Corresponding to the above-mentioned embodiments, as shown in Figure 10 The present application also provides a motor controller, which can include a processor 1 and a memory 2.

[0123] The processor 1 and the memory 2 complete the communication between each other through a communication bus 3.

[0124] The processor 1 is used to execute at least one instruction.

[0125] The memory 2 is used to store at least one instruction.

[0126] The processor 1 can be a central processing unit CPU, or a specific integrated circuit ASIC (Application Specific Integrated Circuit), or one or more integrated circuits configured to implement the embodiments of the present application.

[0127] The memory 2 can comprise a high-speed RAM memory and possibly also a non-volatile memory, for example at least one disk memory.

[0128] wherein the processor executes at least one instruction to implement the following functions:

[0129] When the working environment temperature of the motor controller is lower than a preset temperature limit value, a junction temperature of a power device of the motor controller is estimated by using a pre-established junction temperature estimation model, wherein the junction temperature estimation model is a thermal capacity and thermal resistance model of the power device of the motor controller and a peripheral circuit thereof;

[0130] A current torque limit value of the motor controller is determined according to the junction temperature of the power device and a current bus voltage;

[0131] An output torque value of the motor controller is controlled within the current torque limit value, and a working rotational speed of the motor controller is controlled within a rotational speed limit value, wherein the rotational speed limit value is determined based on a maximum torque current ratio interval.

[0132] In conclusion, the application discloses a motor controller, when the working environment temperature of the motor controller is lower than a preset temperature limit value, a junction temperature of a power device of the motor controller is estimated by using a pre-established junction temperature estimation model, according to the junction temperature of the power device and a current bus voltage, a current torque limit value of the motor controller is determined, an output torque value of the motor controller is controlled within the torque limit value, and a working rotational speed of the motor controller is controlled within a rotational speed limit value. The application determines the current torque limit value of the motor controller based on two dimensions of the junction temperature of the power device and the current bus voltage, controls the output torque value of the motor controller within the torque limit value, and controls the working rotational speed of the motor controller within the rotational speed limit value, so as to inhibit the voltage stress of the power device from exceeding the withstand voltage range, thereby ensuring the working stability of the motor controller.

[0133] Finally, it should be noted that the relationship terms such as first and second, etc. are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment. Without more limitations, the element defined by the statement "including a" does not exclude the presence of another identical element in the process, method, article or equipment including the element.

[0134] The various embodiments described in this specification are presented by way of example, and each embodiment is not necessarily composed of all features described with respect to other embodiments. Each embodiment describes a distinct aspect of the present application, and each aspect can be used in combination with one or more other aspects.

[0135] The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method of low temperature operation of a motor controller, characterized by, The method comprises the steps of: When the working environment temperature of the motor controller is lower than a preset temperature limit, the junction temperature of the power device of the motor controller is estimated by using a pre-established junction temperature estimation model, wherein the junction temperature estimation model is a thermal capacity and thermal resistance model of the power device and the peripheral circuit of the motor controller; A current torque limit value of the motor controller is determined according to the junction temperature of the power device and a current bus voltage; The output torque value of the motor controller is controlled within the current torque limit value, and the working speed of the motor controller is controlled within a speed limit value, wherein the speed limit value is determined based on a maximum torque current ratio interval.

2. The method of claim 1, wherein, The current torque limit value of the motor controller is determined according to the junction temperature of the power device and the current bus voltage, which comprises the steps of: A current limit value is determined based on the junction temperature of the power device and the current bus voltage; The current torque limit value corresponding to the current limit value is determined based on the correspondence between the motor current and the torque limit value of the maximum torque current ratio interval.

3. The method of claim 2, wherein, The current limit value is determined based on the junction temperature of the power device and the current bus voltage, which comprises the steps of: The current limit value corresponding to the junction temperature of the power device and the current bus voltage is found from the correspondence among the measured current peak, the measured junction temperature of the power device and the measured bus voltage.

4. The method of claim 2, wherein, The correspondence between the motor current and the torque limit value of the maximum torque current ratio interval is obtained by piecewise linear or polynomial fitting.

5. The method of claim 1, wherein, The method further comprises the steps of: When the working environment temperature of the motor controller rises to be greater than the preset temperature limit, the motor controller is controlled to restore to a normal output torque value and working speed.

6. The method of claim 1, wherein, The junction temperature estimation model is determined based on the input power of the power device, the thermal resistance of the power device and the thermal capacity of the power device.

7. A device for low-temperature operation of a motor controller, characterized in that, The method comprises the steps of: When the working environment temperature of the motor controller is lower than a preset temperature limit, the junction temperature of the power device of the motor controller is estimated by using a pre-established junction temperature estimation model, wherein the junction temperature estimation model is a thermal capacity and thermal resistance model of the power device and the peripheral circuit of the motor controller; A current torque limit value of the motor controller is determined according to the junction temperature of the power device and a current bus voltage; The output torque value of the motor controller is controlled within the current torque limit value, and the working speed of the motor controller is controlled within a speed limit value, wherein the speed limit value is determined based on a maximum torque current ratio interval.

8. The apparatus of claim 7, wherein, The current torque limit value of the motor controller is determined according to the junction temperature of the power device and the current bus voltage, which comprises the steps of: A current limit value is determined based on the junction temperature of the power device and the current bus voltage; The current torque limit value corresponding to the current limit value is determined based on the correspondence between the motor current and the torque limit value of the maximum torque current ratio interval.

9. The apparatus of claim 8, wherein, The current limit value is determined based on the junction temperature of the power device and the current bus voltage, which comprises the steps of: The current limit value corresponding to the junction temperature of the power device and the current bus voltage is found from the correspondence among the measured current peak, the measured junction temperature of the power device and the measured bus voltage.

10. The apparatus of claim 7, wherein, The correspondence between the motor current and the torque limit value of the maximum torque current ratio interval is obtained by piecewise linear or polynomial fitting. The method further comprises the steps of: When the working environment temperature of the motor controller rises to be greater than the preset temperature limit, the motor controller is controlled to restore to a normal output torque value and working speed. The junction temperature estimation model is determined based on the input power of the power device, the thermal resistance of the power device and the thermal capacity of the power device. The method comprises the steps of: When the working environment temperature of the motor controller is lower than a preset temperature limit, the junction temperature of the power device of the motor controller is estimated by using a pre-established junction temperature estimation model, wherein the junction temperature estimation model is a thermal capacity and thermal resistance model of the power device and the peripheral circuit of the motor controller; A current torque limit value of the motor controller is determined according to the junction temperature of the power device and a current bus voltage; The output torque value of the motor controller is controlled within the current torque limit value, and the working speed of the motor controller is controlled within a speed limit value, wherein the speed limit value is determined based on a maximum torque current ratio interval. The current torque limit value of the motor controller is determined according to the junction temperature of the power device and the current bus voltage, which comprises the steps of: A current limit value is determined based on the junction temperature of the power device and the current bus voltage; The current torque limit value corresponding to the current limit value is determined based on the correspondence between the motor current and the torque limit value of the maximum torque current ratio interval. The current limit value is determined based on the junction temperature of the power device and the current bus voltage, which comprises the steps of: The current limit value corresponding to the junction temperature of the power device and the current bus voltage is found from the correspondence among the measured current peak, the measured junction temperature of the power device and the measured bus voltage. The method further comprises the steps of: A recovery unit is configured to control the motor controller to recover to a normal output torque value and a normal operating speed when the operating environment temperature of the motor controller is greater than the preset temperature limit.

11. The apparatus of claim 7, wherein, The junction temperature estimation model is determined based on input power of the power device, thermal resistance of the power device, and thermal capacity of the power device.

12. An electric machine controller characterized by The motor controller comprises a memory and a processor. The memory is configured to store at least one instruction. The processor is configured to execute the at least one instruction to implement the method for low-temperature operation of the motor controller according to any one of claims 1-6.

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