Modulation method and system for improving temperature rise of controller diode of asynchronous motor

Abstract

The embodiment of the invention provides a modulation method and system for improving temperature rise of a controller diode of an asynchronous motor, and belongs to the technical field of semiconductors. The modulation method comprises the following steps: acquiring the working condition of a current system; judging whether the current working condition triggers a preset triggering working condition or not; and under the condition that it is judged that the current working condition triggers the triggering working condition, the action time of the 0 vector of the motor is adjusted according to a preset temperature threshold value. According to the invention, through optimization of wave generation of the controller, junction temperatures under various working conditions can be improved, the current control performance can be ensured, and the cost can be reduced on the premise that a hardware circuit is not changed.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a modulation method and system for improving the temperature rise of a controller diode of an asynchronous motor. Background Art

[0002] When electric vehicles are climbing steep slopes, they are usually in a low-speed and high-torque state. If this condition lasts for a long time, the junction temperature of the controller may suddenly rise, which may cause the vehicle to slip due to derating. In severe cases, the power device may be damaged due to excessively high junction temperature of the controller, causing the vehicle to lose power, thus creating a great safety hazard. Currently, many four-wheel drive electric vehicles use asynchronous motors for the front drive, and the modulation algorithm is SVPWM. In some extreme working conditions, such as stalled working conditions or low-speed and high-torque working conditions, the asynchronous motor controller uses the SVPWM algorithm, and the junction temperature of the controller will be very high. Generally speaking, the junction temperature of the diode will be higher than the junction temperature of the IGBT. When the temperature of the power module device exceeds 150°C, its reliability and life will be affected, which in turn affects the reliability and safety of the entire vehicle. Therefore, how to effectively control the junction temperature of the diode is extremely important for asynchronous motor control and the use of the entire vehicle.

[0003] At present, the DPWM algorithm is mainly used to reduce the number of switching times. Under electric and power generation conditions, it has a certain effect on reducing the junction temperature. However, for stalled or low-speed and high-torque conditions, under certain motor angles, it has a worsening effect on the controller junction temperature. In addition, DPWM will also make the current control performance of the electric drive system worse. Or by adjusting the parameters of the hardware drive circuit, the junction temperature can be effectively reduced regardless of electric, power generation and extreme conditions. However, for mass-produced products, modifying the hardware parameters requires replacing the corresponding electronic components, which involves design changes and BOM changes, which will cause huge losses to the company. Summary of the invention

[0004] In order to achieve the above-mentioned purpose, the present invention provides a modulation method and system for improving the temperature rise of the controller diode of an asynchronous motor, which solves the problem of effectively controlling the junction temperature of the diode.

[0005] The object of the present invention is to provide a modulation method for improving the temperature rise of a controller diode of an asynchronous motor, the modulation method comprising:

[0006] Get the current system status;

[0007] Determine whether the current working condition triggers the preset triggering condition;

[0008] When it is determined that the current operating condition triggers the triggering operating condition, the action time of the zero vector of the motor is adjusted according to a preset temperature threshold.

[0009] Optionally, obtain the current system status, including:

[0010] Get the current system speed and torque.

[0011] Optionally, determining whether the current operating condition triggers a preset triggering condition includes:

[0012] Determining whether the rotational speed is less than a preset rotational speed threshold and whether the torque is greater than or equal to a preset torque threshold;

[0013] In the case of determining whether the rotational speed is less than a preset rotational speed threshold and the torque is greater than or equal to a preset torque threshold, determining that the current operating condition triggers the triggering operating condition;

[0014] In the case of judging whether the rotation speed is greater than or equal to the rotation speed threshold and / or the torque is less than the torque threshold, it is determined that the current operating condition does not trigger the triggering operating condition.

[0015] Optionally, the speed threshold is 500 rpm, and the torque threshold is 240 Nm.

[0016] Optionally, when it is determined that the current operating condition triggers the triggering operating condition, adjusting the action time of the zero vector of the motor according to a preset temperature threshold includes:

[0017] Obtaining the current temperature of the diode of the three-phase bridge arm of the motor;

[0018] Determining a maximum duty cycle of three-phase current according to the current temperature and a preset threshold temperature;

[0019] The action time of the zero vector is calculated according to the maximum duty cycle.

[0020] Optionally, calculating the action time of the 0 vector according to the maximum duty cycle includes:

[0021] The action time of the 0 vector is calculated according to formula (1):

[0022] t 0 =t s -t x -t y (1)

[0023] Among them, t s is a PWM cycle, t x and t y is the action time of adjacent vectors in sectors 1 to 6, t 0 The action time of the 0 vector.

[0024] Optionally, the modulation method further includes:

[0025] When it is determined that the current working condition does not trigger the triggering working condition, the SVPWM method is used to calculate the action time of adjacent vectors;

[0026] The action time and the maximum duty cycle of the 0 vector are calculated according to the action time of the adjacent vectors.

[0027] Optionally, when it is determined that the current operating condition does not trigger the triggering operating condition, an SVPWM method is used to calculate the adjacent vector action time;

[0028] The action time and the maximum duty cycle of the 0 vector are calculated according to the action time of the adjacent vectors.

[0029] Optionally, when it is determined that the current operating condition does not trigger the triggering operating condition, the SVPWM method is used to calculate the action time of adjacent vectors, including:

[0030] According to formulas (2) to (3), the action time of adjacent vectors is calculated:

[0031]

[0032] Among them, T k and T k+1 is the action time of adjacent vectors, m is the SVPWM modulation ratio, θ is the angle between the synthetic vector and the α axis, T S is the PWM period, K=1, 2, 3, 4, 5, 6.

[0033] Optionally, calculating the action time and the maximum duty cycle of the 0 vector according to the action time of the adjacent vectors includes:

[0034] According to formulas (4) to (5), the action time and maximum duty cycle of the zero vector are calculated.

[0035]

[0036] Among them, T k and T k+1 is the action time of adjacent vectors, T S is the PWM period, K=1, 2, 3, 4, 5, 6, D is the maximum duty cycle, T 0 The action time of the 0 vector.

[0037] On the other hand, the present invention provides a modulation system for improving the temperature rise of a controller diode of an asynchronous motor, the modulation system comprising:

[0038] Motor;

[0039] The working condition judgment module is used to obtain the working condition of the current system and judge whether the current working condition triggers the preset triggering condition;

[0040] A PI controller, connected to the working condition judgment module, for adjusting the action time of the zero vector of the motor according to a preset temperature threshold;

[0041] A PWM generator is connected to the PI controller and the motor, and is used to drive the motor according to the action time of the 0 vector.

[0042] Through the above technical scheme, the present invention provides a modulation method and system for improving the temperature rise of the controller diode of an asynchronous motor. First, the working condition of the current system is obtained, and it is determined whether the current working condition triggers the preset triggering working condition. When it is determined that the current working condition triggers the triggering working condition, the action time of the motor's 0 vector is adjusted according to the preset temperature threshold to obtain the maximum duty cycle. When it is determined that the current working condition does not trigger the triggering working condition, the SVPWM method is used to determine the maximum duty cycle of the three-phase current to achieve control of the electric drive system. The present invention can reduce the junction temperature of the diode to the maximum extent, and the effect is particularly obvious for the locked rotor working condition and the low-speed working condition. Since the total loss does not change, it has no effect on the efficiency of the controller, and also has no effect on NVH, ensuring the reliability and life of the controller, thereby ensuring the safety of the whole vehicle. And it has no effect on the control of the current loop, and the current fluctuation and the output voltage are consistent with SVPWM. Compared with the prior art, the present invention can improve the junction temperature under various working conditions and ensure the current control performance by optimizing the controller wave, and can also reduce the cost without changing the hardware circuit.

[0043] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings:

[0045] Figure 1 is a flow chart of a modulation method according to one embodiment of the present invention;

[0046] Figure 2 is a flow chart for determining whether a current operating condition triggers a preset triggering condition according to an embodiment of the present invention;

[0047] Figure 3 is a flow chart of adjusting the action time of the 0 vector of the motor by a preset temperature threshold according to one embodiment of the present invention;

[0048] Figure 4 is a control block diagram of a control method according to one embodiment of the present invention. DETAILED DESCRIPTION

[0049] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment of the present invention.

[0050] In the embodiments of the present invention, unless otherwise specified, directional words such as "up, down, top, bottom" are usually used with reference to the directions shown in the drawings or are used to describe the relative positional relationships of components in the vertical, perpendicular or gravity direction.

[0051] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0052] Figure 1 is a flow chart of a modulation method according to an embodiment of the present invention, in which the modulation method comprises:

[0053] In step S1, the current operating condition of the system is obtained.

[0054] In step S2, it is determined whether the current operating condition triggers a preset triggering condition. If it is determined that the current operating condition triggers the triggering condition, step S3 is executed.

[0055] In step S3 , the action time of the zero vector of the motor is adjusted according to a preset temperature threshold.

[0056] In such Figure 1In the modulation method, the action time of the 0 vector is adjusted, and the three-phase duty cycle can be changed eventually. The essence of changing the duty cycle is to reduce the loss of the diode, thereby changing the temperature distribution of the upper and lower bridge arm IGBTs and the diode. The present invention can reduce the junction temperature of the diode to the maximum extent, and the effect is particularly obvious for locked-rotor conditions and low-speed conditions. Since the total loss does not change, it has no effect on the efficiency of the controller. In addition, it has no effect on NVH, ensuring the reliability and life of the controller, thereby ensuring the safety of the entire vehicle. And it has no effect on the control of the current loop, and the current fluctuation and the output voltage are consistent with SVPWM. Compared with the prior art, the present invention can not only improve the junction temperature under various working conditions, but also ensure the current control performance, and reduce the cost without changing the hardware circuit by optimizing the controller wave.

[0057] In this implementation, the operating conditions of the system to be obtained may be various ones known to those skilled in the art. In one example of the present invention, obtaining the operating conditions of the current system includes obtaining the rotational speed and torque of the current system.

[0058] The system's operating condition is determined by the system's speed and torque. When the system is in a low-speed, high-torque operating condition, that is, the vehicle's climbing condition, the system satisfies the conditions that the speed is less than the set speed threshold and the torque is greater than or equal to the set torque threshold. In this embodiment, there are many ways to determine whether the current operating condition triggers the preset triggering condition. In one example of the present invention, it can be as follows: Figure 2 Specifically, the following steps may be included:

[0059] In step S21, it is determined whether the speed is less than a preset speed threshold and whether the torque is greater than or equal to a preset torque threshold. If it is determined whether the speed is less than a preset speed threshold and the torque is greater than or equal to a preset torque threshold, step S22 is executed, otherwise, step S32 is executed.

[0060] In step S22, it is determined whether the current operating condition triggers the triggering operating condition.

[0061] In step S23, it is determined that the current operating condition does not trigger the triggering condition.

[0062] In this embodiment, the values ​​of the speed threshold and the torque threshold can be multiple values ​​known to those skilled in the art. In one example of the present invention, the speed threshold is 500 rpm, and the torque threshold corresponds to 80% of the peak torque of the motor, which is 240 Nm.

[0063] In this implementation, the specific content of adjusting the action time of the 0 vector of the motor according to the preset temperature threshold may be various known to those skilled in the art. In one example of the present invention, for example Figure 3 As shown, this may include:

[0064] In step S31, the current temperature of the diodes of the three-phase bridge arms of the motor is obtained.

[0065] In step S32, the maximum duty cycle of the three-phase current is determined according to the current temperature and the preset threshold temperature. The maximum duty cycle can be obtained by judging the maximum and minimum values ​​of the three-phase current. Since the vector sum of the three-phase current of the motor is zero, the current value of the middle phase can be obtained according to the maximum and minimum values ​​of the three-phase current. According to the current values ​​of the three phases, the motor angle can be indirectly reflected to calibrate the maximum duty cycle, and finally output a new three-phase duty cycle. The calibration method is simple, highly operational, and can quickly and effectively obtain results. Among them, the three-phase current needs to be filtered to ensure that the three-phase current is stable and does not jump abnormally.

[0066] In step S33, the action time of the 0 vector is calculated according to the maximum duty cycle.

[0067] In this implementation, there may be various methods known to those skilled in the art for calculating the action time of the 0 vector. In one example of the present invention, the method may include:

[0068] According to formula (1), the action time of 0 vector is calculated:

[0069] t 0 =t s -t x -t y (1)

[0070] Among them, t s is a PWM cycle, t x and t y is the action time of adjacent vectors in sectors 1 to 6, t 0 The action time of the 0 vector.

[0071] When it is determined that the current working condition does not trigger the triggering working condition, the modulation method for improving the temperature rise of the controller diode of the asynchronous motor can be various methods known to those skilled in the art. In one example of the present invention, specifically, the following steps can be included:

[0072] In step S4, the SVPWM method is used to calculate the action time of adjacent vectors.

[0073] In step S5, the action time and the maximum duty cycle of the 0 vector are calculated according to the action times of adjacent vectors.

[0074] In this implementation, the specific contents of calculating the adjacent vector action time using the SVPWM method may include:

[0075] According to formulas (2) to (3), the action time of adjacent vectors is calculated:

[0076]

[0077] Among them, T k and T k+1 is the action time of adjacent vectors, m is the SVPWM modulation ratio, θ is the angle between the synthetic vector and the α axis, T S is the PWM period, K=1, 2, 3, 4, 5, 6.

[0078] Further, the action time and the maximum duty cycle of the 0 vector are calculated according to the action time of the adjacent vectors, including:

[0079] According to formulas (4) to (5), the action time and maximum duty cycle of the zero vector are calculated.

[0080]

[0081] Among them, T k and T k+1 is the action time of adjacent vectors, T S is the PWM period, K=1, 2, 3, 4, 5, 6, D is the maximum duty cycle, T 0 The action time of the 0 vector.

[0082] On the other hand, the present invention provides a modulation system for improving the temperature rise of the controller diode of an asynchronous motor, the modulation system comprising a motor, a working condition judgment module, a PI controller and a PWM generator. The working condition judgment module is used to obtain the working condition of the current system and judge whether the current working condition triggers a preset triggering condition, the PI controller is connected to the working condition judgment module, and is used to adjust the action time of the motor's 0 vector according to a preset temperature threshold, and the PWM generator is connected to the PI controller and the motor, and is used to drive the motor according to the action time of the 0 vector. Figure 4 is a control block diagram of a control method according to one embodiment of the present invention.

[0083] Through the above technical scheme, the present invention provides a modulation method and system for improving the temperature rise of the controller diode of an asynchronous motor. First, the working condition of the current system is obtained, and it is determined whether the current working condition triggers the preset triggering working condition. When it is determined that the current working condition triggers the triggering working condition, the action time of the motor's 0 vector is adjusted according to the preset temperature threshold to obtain the maximum duty cycle. When it is determined that the current working condition does not trigger the triggering working condition, the SVPWM method is used to determine the maximum duty cycle of the three-phase current to achieve control of the electric drive system. The present invention can reduce the junction temperature of the diode to the maximum extent, and the effect is particularly obvious for the locked rotor working condition and the low-speed working condition. Since the total loss does not change, it has no effect on the efficiency of the controller, and also has no effect on NVH, ensuring the reliability and life of the controller, thereby ensuring the safety of the whole vehicle. And it has no effect on the control of the current loop, and the current fluctuation and the output voltage are consistent with SVPWM. Compared with the prior art, the present invention can improve the junction temperature under various working conditions and ensure the current control performance by optimizing the controller wave, and can also reduce the cost without changing the hardware circuit.

[0084] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0085] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. Information can be computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0086] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0087] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A modulation method for improving the temperature rise of a controller diode of an asynchronous motor, characterized in that: The modulation method comprises: Get the current system status; Determine whether the current working condition triggers the preset triggering condition; When it is determined that the current operating condition triggers the triggering operating condition, the action time of the zero vector of the motor is adjusted according to a preset temperature threshold.

2. The modulation method according to claim 1, characterized in that: Get the current system status, including: Get the current system speed and torque.

3. The modulation method according to claim 2, characterized in that: Determine whether the current working condition triggers the preset triggering condition, including: Determining whether the rotational speed is less than a preset rotational speed threshold and whether the torque is greater than or equal to a preset torque threshold; In the case of determining whether the rotational speed is less than a preset rotational speed threshold and the torque is greater than or equal to a preset torque threshold, determining that the current operating condition triggers the triggering operating condition; In the case of judging whether the rotation speed is greater than or equal to the rotation speed threshold and / or the torque is less than the torque threshold, it is determined that the current operating condition does not trigger the triggering operating condition.

4. The modulation method according to claim 3, characterized in that: The speed threshold is 500 rpm, and the torque threshold is 240 Nm.

5. The modulation method according to claim 4, characterized in that: When it is determined that the current operating condition triggers the triggering operating condition, adjusting the action time of the zero vector of the motor according to a preset temperature threshold comprises: Obtaining the current temperature of the diode of the three-phase bridge arm of the motor; Determining a maximum duty cycle of three-phase current according to the current temperature and a preset threshold temperature; The action time of the zero vector is calculated according to the maximum duty cycle.

6. The modulation method according to claim 5, characterized in that: Calculating the action time of the 0 vector according to the maximum duty cycle includes: The action time of the 0 vector is calculated according to formula (1): t0=t s -t x -t y (1) Among them, t s is a PWM cycle, t x and t y is the action time of adjacent vectors in sectors 1 to 6, and t0 is the action time of vector 0.

7. The modulation method according to claim 1, characterized in that: The modulation method further comprises: When it is determined that the current working condition does not trigger the triggering working condition, the SVPWM method is used to calculate the action time of adjacent vectors; The action time and the maximum duty cycle of the 0 vector are calculated according to the action time of the adjacent vectors.

8. The modulation method according to claim 7, characterized in that: When it is determined that the current working condition does not trigger the triggering working condition, the SVPWM method is used to calculate the action time of adjacent vectors, including: According to formulas (2) to (3), the action time of adjacent vectors is calculated: Among them, T k and T k+1 is the action time of adjacent vectors, m is the SVPWM modulation ratio, θ is the angle between the synthetic vector and the α axis, T s is the PWM period, K=1, 2, 3, 4, 5, 6.

9. The modulation method according to claim 8, characterized in that: Calculating the action time and maximum duty cycle of the 0 vector according to the action time of the adjacent vectors includes: According to formulas (4) to (5), the action time and maximum duty cycle of the zero vector are calculated. Among them, T k and T k+1 is the action time of adjacent vectors, T S is the PWM period, K=1, 2, 3, 4, 5, 6, D is the maximum duty cycle, and T0 is the action time of the 0 vector.

10. A modulation system for improving the temperature rise of a controller diode of an asynchronous motor, characterized in that: The modulation system comprises: Motor; The working condition judgment module is used to obtain the working condition of the current system and judge whether the current working condition triggers the preset triggering condition; A PI controller, connected to the working condition judgment module, for adjusting the action time of the zero vector of the motor according to a preset temperature threshold; A PWM generator is connected to the PI controller and the motor, and is used to drive the motor according to the action time of the 0 vector.

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