Permanent magnet motor dead zone compensation method and device and permanent magnet motor system

Abstract

The application discloses a kind of permanent magnet motor dead zone compensation method, device and permanent magnet motor system.The compensation method includes: obtaining the current feedback value and current instruction value of permanent magnet motor;According to the size relationship between current feedback value and preset zero-crossing current interval, the positive and negative polarity of current feedback value is judged;Combining the positive and negative polarity of current feedback value, the corresponding compensation amount is calculated according to current instruction value, to carry out dead zone compensation to permanent magnet motor.The noise of feedback current when feedback current zero-crossing point will not affect dead zone compensation, so as to avoid the problem that dead zone compensation appears compensation error, overcompensation or even compensation error when feedback current is at zero-crossing point, improve the reliability of dead zone compensation, so that permanent magnet motor runs more stably.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of permanent magnet motor, more particularly, relates to a permanent magnet motor dead-time compensation method and device and a permanent magnet motor system. BACKGROUND

[0002] Permanent magnet motor is a kind of motor that uses permanent magnet to generate magnetic field without external excitation, which has the characteristics of high efficiency, energy saving and simple structure. Permanent magnet propulsion motor is a kind of permanent magnet motor, which is driven to run by a driver. The driver adopts pulse width modulation to output three-phase sinusoidal current. Since pulse width modulation is adopted for output, there is dead-time, which will cause distortion of inverter output voltage and generation of harmonics. Especially in the condition of low frequency operation, voltage and current will be severely distorted, and output torque will oscillate greatly, which is very unfavorable for the control of inverter motor, and finally leads to excessive noise of the motor, so dead-time compensation is needed.

[0003] In the prior art, dead-time compensation is usually carried out according to the actual current. During the dead-time compensation process, when the current is at zero crossing point, the current value is very small at this time, and there is current oscillation at the zero crossing point, which may repeatedly oscillate near the zero point, resulting in inaccurate compensation, over-compensation or even compensation error at the current zero crossing point, thereby increasing the current harmonic content or causing abnormal current waveform. SUMMARY

[0004] In view of the deficiencies of the prior art, the purpose of the present application is to provide a permanent magnet motor dead-time compensation method, device and permanent magnet motor system to solve the problem that the dead-time compensation according to the actual current value in the prior art may cause inaccurate compensation, over-compensation or even compensation error at the current zero crossing point.

[0005] To achieve the above purpose, the first aspect of the present application provides a permanent magnet motor dead-time compensation method, which comprises: obtaining a current feedback value and a current command value of a permanent magnet motor; determining the positive or negative polarity of the current feedback value according to the size relationship between the current feedback value and a preset zero-crossing current interval; when the current feedback value is in the positive half cycle and the current command value is greater than the maximum value of the preset zero-crossing current interval, using a first compensation amount to compensate the dead-time of the permanent magnet motor; when the current feedback value is in the negative half cycle and the current command value is less than the minimum value of the preset zero-crossing current interval, using a second compensation amount to compensate the dead-time of the permanent magnet motor; when the current feedback value is in the current zero-crossing point interval, using a third compensation amount to compensate the dead-time of the permanent magnet motor.

[0006] Optionally, judging the positive and negative polarity of the current feedback value specifically includes: if the current feedback value is greater than the maximum value of the preset zero-crossing current interval, the current feedback value is in a current positive half cycle; if the current feedback value is less than the minimum value of the preset zero-crossing current interval, the current feedback value is in a current negative half cycle; if the current feedback value is within the preset zero-crossing current interval, the current feedback value is in a current zero-crossing point interval.

[0007] Optionally, the first compensation amount, the second compensation amount and the third compensation amount are respectively:

[0008] ;

[0009] wherein dx_1 is the first compensation amount, dx_2 is the second compensation amount, dx_3 is the third compensation amount, K is a compensation coefficient, K>0, is a first dead zone compensation voltage amount, ≥0, is a second dead zone compensation voltage amount, ≥0.

[0010] Optionally, is:

[0011] ;

[0012] wherein k1 is a derating coefficient, k1 is adjusted according to the current falling time when the power device in the permanent magnet motor is turned off; T1 is a dead time, U is a bus voltage, and T2 is a modulation period for pulse width modulation of the permanent magnet motor.

[0013] Optionally, is:

[0014] ;

[0015] wherein k2 is an attenuation coefficient; k3 is a proportional value, k3=V2 / I cmd , V2 is a tube voltage drop generated by the power device in the driver at I cmd ; k2≥0; I cmd is the current command value, and V1 is the maximum tube voltage drop of the power device in the driver.

[0016] Optionally, is a preset fixed value.

[0017] Optionally, is a preset fixed value.

[0018] Optionally, the preset zero-crossing current interval is [-I cmdmin , I cmdmin ], Icmdmin is:

[0019]

[0020] wherein, I cmdmin is the absolute value of the preset upper and lower limit of the zero-crossing current interval, m2 is the minimum zero-current interval judgment coefficient, I n is the rated current value of the driver driving the power device in the permanent magnet motor, and m1 is the internal current value calculation accuracy of the driver.

[0021] The second aspect of the present application provides a dead zone compensation device for a permanent magnet motor, for dead zone compensation of an N-phase permanent magnet motor, N≥1, the device comprising N single-phase dead zone compensation modules, one-to-one corresponding to the N phases of the permanent magnet motor; the single-phase dead zone compensation module comprises a submodule for executing the operation steps of the above method, for dead zone compensation of the corresponding output phase current of the permanent magnet motor driver.

[0022] The third aspect of the present application provides a permanent magnet motor system, the system comprising a permanent magnet motor and a permanent magnet motor dead zone compensator, the permanent magnet motor dead zone compensator executing the method as described above.

[0023] Compared with the prior art, the advantages of the present application include: a permanent magnet motor dead zone compensation method, device and permanent magnet motor system are provided, the position of the current feedback value in the current cycle is judged, and then the relationship between the given current (i.e. current command value) of the permanent magnet motor and the dead zone compensation amount is established; the dead zone compensation amount is calculated from the given current, since the given current is more stable and has small noise, when the dead zone is compensated according to the given current, the effect that the dead zone compensation does not affect the current control when the feedback current crosses zero can be achieved; interval judgment is not inaccurate or the feedback current noise is too large, so that the compensation value calculated according to the feedback current is wrong, the compensation is not enough or overcompensation. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The flowchart of the permanent magnet motor dead zone compensation method provided by the embodiment of the present application.

[0025] Figure 2 The principle block diagram of the permanent magnet motor dead zone compensation method provided by the embodiment of the present application.

[0026] Figure 3 The given phase current and feedback waveform diagram provided by the embodiment of the present application.

[0027] Figure 4 The schematic diagram of the electronic device provided by the embodiment of the present application. DETAILED DESCRIPTION

[0028] ​In view of the deficiencies in the prior art, the present inventors have long studied and practiced to propose the technical solution of the present application. The technical solution, its implementation process and principles will be further explained as follows.

[0029] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be practiced in other ways that are not exactly as described in this description, and the scope of the present application is not limited to the specific embodiments disclosed in this description.

[0030] In addition, in the description of the present application, it should be understood that the terms "upper", "lower", "inner", "outer", "horizontal", "vertical" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0031] In the description of the present application, the description of the terms "one embodiment", "an embodiment", "the embodiment" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present description, the illustrative description of the above terms is not necessarily directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0032] The embodiment of the present application provides a permanent magnet motor dead zone compensation method. Referring to Figure 1 , the permanent magnet motor dead zone compensation method comprises steps S100-S300.

[0033] Step S100, obtaining the current feedback value and the current command value of the permanent magnet motor.

[0034] The permanent magnet motor may be, for example, a permanent magnet propulsion motor, or other permanent magnet motor. The permanent magnet motor may be a single-phase permanent magnet motor or a multi-phase permanent magnet motor, for example, a three-phase permanent magnet motor. For a multi-phase permanent magnet motor, the phase current feedback value and the phase current command value of each phase are obtained in step S100.

[0035] The current feedback value is, for example, the winding current value of the permanent magnet motor detected in real time by a current sensor, which may have current oscillation near the zero-crossing point; the current command value is the given winding current designed for the permanent magnet motor, which does not have current oscillation near the zero-crossing point.

[0036] Step S200, judging the positive and negative polarity of the current feedback value according to the size relationship between the current feedback value and the preset zero-crossing current interval.

[0037] In a preferred embodiment, the determination rule in step S200 specifically comprises: if the current feedback value I fbx is greater than the maximum value of the preset zero-crossing current interval, it is determined that the current feedback value is in the positive half cycle; if the current feedback value I fbx is less than the minimum value of the preset zero-crossing current interval, it is determined that the current feedback value is in the negative half cycle; if the current feedback value I fbx is in the preset zero-crossing current interval, it is determined that the current feedback value is in the zero-crossing point interval. fbx and I cmdx , wherein x is u, v or w, representing the u-phase, the v-phase or the w-phase.

[0038] In a preferred embodiment, the preset zero-crossing current interval is [-I cmdmin , I cmdmin ], I cmdmin > 0, that is, the maximum value and the minimum value of the preset zero-crossing current interval are equal in absolute value. Preferably, I cmdmin is:

[0039] ;

[0040] wherein I cmdmin is the absolute value of the upper and lower limits of the preset zero-crossing current interval, m2 is the minimum zero-crossing current interval determination coefficient, I n is the rated current value of the permanent magnet motor driver, and m1 is the internal current value calculation accuracy of the driver. m2 needs to be valued according to the actual current control effect, generally ≤1%. Within the range of [-I cmdmin , I cmdmin ], since the compensation value is calculated by I cmd , the higher the calculation accuracy of I cmd , the higher the dead zone compensation accuracy.

[0041] The determination rule in step S200 is specifically as follows: when I fbx >I cmdmin , the current feedback value is in the positive half cycle, which is in a positive polarity state; when I fbx <-I cmdmin , the current feedback value is in the negative half cycle, which is in a negative polarity state; when -I cmdmin ≤I fbx ≤I cmdmin , the current feedback value is in the zero-crossing point interval, which is in a zero polarity state.

[0042] Step S300, when the current feedback value is in the positive half cycle of the current and the current command value is greater than the maximum value of the preset zero-crossing current interval, the first compensation amount is used to compensate the dead zone of the permanent magnet motor; when the current feedback value is in the negative half cycle of the current and the current command value is less than the minimum value of the preset zero-crossing current interval, the second compensation amount is used to compensate the dead zone of the permanent magnet motor; when the current feedback value is in the current zero-crossing point interval, the third compensation amount is used to compensate the dead zone of the permanent magnet motor.

[0043] Taking the preset zero-crossing current interval [-I cmdmin ,I cmdmin ] as an example, the specific compensation method in step S300 is: (1) when the current feedback value I fbx is in the positive half cycle of the current and I cmdx >I cmdmin , the first compensation amount is used to compensate the dead zone of the permanent magnet motor; (2) when the current feedback value I fbx is in the negative half cycle of the current and I cmdx <-I cmdmin , the second compensation amount is used to compensate the dead zone of the permanent magnet motor; (3) when the current feedback value is in the current zero-crossing point interval, the third compensation amount is used to compensate the dead zone of the permanent magnet motor, and the third compensation amount dx_3=0 or . It should be noted that when I cmdmin is small enough and the control of the current has no effect, the compensation amount can be approximately ignored, the third compensation amount dx_3=0, and the permanent magnet motor is not compensated.

[0044] It should be noted that there is no case that the current feedback value I fbx is in the positive half cycle of the current and the current command value I cmdx is less than the minimum value of the preset zero-crossing current interval, and there is no case that the current feedback value I fbx is in the negative half cycle of the current and the current command value I cmdx is greater than the maximum value of the preset zero-crossing current interval.

[0045] The first compensation amount and the second compensation amount are both parameters for compensating the output voltage of the propulsion motor. In a preferred embodiment, the first compensation amount, the second compensation amount and the third compensation amount are respectively:

[0046] ;

[0047] wherein dx_1 is the first compensation amount, dx_2 is the second compensation amount, dx_3 is the third compensation amount, K is a compensation coefficient, 1≥K>0, is the first dead zone compensation voltage amount, ≥0, is the second dead zone compensation voltage amount, ≥0. 、 After determining the specific value of K, the wave modulation processing can be performed on the overall current waveform, and the target is to reduce the 5th, 7th, 11th and 13th current harmonics at the corresponding speed, according to different I cmd and actual harmonic reduction values, different K values are determined, and a K value table corresponding to the current speed is established. cmd

[0048] The embodiments of the application provide two preferred 、 value schemes.

[0049] In the above scheme, is:

[0050] ;

[0051] wherein k1 is a derating coefficient, k1 is adjusted according to the current drop time when the power device in the permanent magnet motor is turned off, so as to prevent the compensation from being too large; T1 is a dead time, U is a bus voltage, and T2 is a modulation period of pulse width modulation for the permanent magnet motor.

[0052] In the above scheme, is:

[0053] ;

[0054] wherein k2 is an attenuation coefficient; k3 is a proportional value, k3=V2 / I cmd , V2 is a tube voltage drop of the power device in the driver under I cmd ; k2>=0; I cmd is a current command value, and V1 is a maximum tube voltage drop of the power device in the driver. At the zero crossing point, the compensation obtained by using the current command value in combination with the tube voltage drop curve can better compensate for the dead time and further reduce the harmonic content. k2 is an actual value obtained by adjusting the actual current waveform according to the given current size and the actual current waveform state. k3 is a group of values that change according to the given current. It should be noted that when I cmd is small enough, is approximately 0, and the third compensation is 0.

[0055] In yet another preferred scheme, and / or is a preset fixed value.

[0056] ​The permanent magnet motor dead zone compensation method provided by the embodiment of the application establishes the relationship among the given current (i.e. the current command value) of the permanent magnet motor, the feedback current (i.e. the current feedback value) and the dead zone compensation amount, so that the noise of the feedback current at the zero point of the feedback current does not affect the dead zone compensation, thereby reducing the risk that the dead zone compensation is inaccurate or overcompensated or even wrong at the zero point of the feedback current, resulting in an increase in the current harmonic content or even abnormal current waveform.

[0057] The technical solutions of the application will be further described in detail below with reference to the drawings and some preferred embodiments. Obviously, the described embodiments are only some of the embodiments of the application, but not all the embodiments. Based on the embodiments of the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application. The test methods not specified in the following embodiments are usually performed according to the conventional conditions.

[0058] In combination with Figures 2-3 , the permanent magnet motor dead zone compensation method in the embodiment of the application is described by taking a three-phase permanent magnet propulsion motor as an example.

[0059] Referring to Figure 2 , in the embodiment, the x-phase polarity judging device is used to implement step S200, and the positive and negative polarities of the x-phase current feedback value of the three-phase permanent magnet propulsion motor are judged; and the x-phase compensation amount calculator is used to implement step S300, and the compensation amount required by the dead zone compensation is calculated, wherein x is any one of u, v and w.

[0060] The x-phase polarity judging device receives the x-phase current feedback value I fbx of the permanent magnet propulsion motor, and judges the position of the circuit cycle according to the size of I fbx . Referring to Figure 3 , when I fbx >I cmdmin , the x-phase current feedback value is in the positive half cycle of the current, and is of positive polarity, and the x-phase polarity judging device outputs the positive polarity state to the x-phase compensation amount calculator; when I fbx <-I cmdmin , the x-phase current feedback value is in the negative half cycle of the current, and is of negative polarity, and the x-phase polarity judging device outputs the negative polarity state to the x-phase compensation amount calculator; when -I cmdmin ≤I fbx ≤I cmdmin , the x-phase current feedback value is at the zero point, and the x-phase polarity judging device outputs the zero point state to the x-phase compensation amount calculator.

[0061] The x-phase compensation amount calculator receives the x-phase current command value I cmdx of the permanent magnet propulsion motor and the polarity state output by the x-phase polarity judging device (I Figure 2In the equation (where ax, bx, and cx represent the positive polarity state, negative polarity state, and zero-crossing state, respectively), based on the received x-phase current command value I... cmdx Based on the polarity state of the x-phase current feedback value, calculate the compensation amount dx and output it, so that the controller can perform dead zone compensation for the permanent magnet propulsion motor according to the compensation amount dx.

[0062] When the x-phase current feedback value is in a positive polarity state: if I cmdx >I cmdmin Then the compensation amount , if -I cmdmin ≤I cmdx ≤I cmdmin Then the compensation amount dx = 0 or When the x-phase current feedback value is in a negative polarity state: if I cmdx <-I cmdmin Then the compensation amount , if -I cmdmin ≤I cmdx ≤I cmdmin Then the compensation amount dx = 0 or When the x-phase current feedback value is at the zero-crossing point, the compensation amount dx = 0 or . and / or It can be a fixed value; Alternatively, the compensation value can be obtained by looking up a table based on the current setpoint. With current given value I cmdx Relationship Stored in a table, when I cmd Enough hours Approximately 0 ; for The compensation table can be stored in devices such as microcontroller units (MCUs), field-programmable gate arrays (FPGAs), electrically erasable programmable read-only memory (EEPROM), and read-only memory (ROM).

[0063] The dead-zone compensation method for permanent magnet motors provided in this embodiment is designed for multi-phase permanent magnet propulsion motors. By establishing the relationship between the given current, feedback current, and dead-zone compensation amount for each phase of the permanent magnet propulsion motor, it ensures that feedback current noise does not affect dead-zone compensation when the feedback current crosses zero, thereby further reducing the following risks: Due to the significant noise of the feedback current, it interferes with compensation, especially at zero-crossing points. Feedback current oscillations can lead to inaccurate judgments, and dead-zone compensation may be inaccurate, over-compensated, or even incorrect at zero-crossing points, resulting in increased current harmonic content and even abnormal current waveforms. This method makes the permanent magnet propulsion motor drive controller system more stable.

[0064] The method provided by the application has more stable given current and small noise, and when the dead zone is compensated according to the given current, interval judgment is not inaccurate or noise is too large, so that the compensation value calculated according to the current is wrong, compensation is insufficient or overcompensation occurs. In addition, at the zero-crossing point, the current given value is combined with the tube voltage drop curve to better compensate for the dead zone and further reduce the harmonic content.

[0065] Based on the same inventive concept, the application also provides a permanent magnet motor dead zone compensation device corresponding to any of the above-mentioned embodiment methods. The device comprises N single-phase dead zone compensation modules, which correspond one-to-one to N phases of the permanent magnet motor. For each single-phase dead zone compensation module, it comprises a submodule for executing the operation steps of the permanent magnet motor dead zone compensation method in the above-mentioned embodiment, for dead zone compensation of the corresponding phase of the permanent magnet motor.

[0066] For each single-phase dead zone compensation module, it comprises, for example, an acquisition submodule, a judgment submodule and a compensation submodule. The acquisition submodule, for example, executes step S100, for acquiring the current feedback value and the current instruction value of the permanent magnet motor. The judgment submodule, for example, executes step S200, for judging the positive and negative polarity of the current feedback value according to the size relationship between the current feedback value and the preset zero-crossing current interval. The compensation submodule, for example, executes step S300, for dead zone compensation of the permanent magnet motor by using a first compensation amount when the current feedback value is in the current positive half cycle and the current instruction value is greater than the maximum value of the preset zero-crossing current interval; dead zone compensation of the permanent magnet motor by using a second compensation amount when the current feedback value is in the current negative half cycle and the current instruction value is less than the minimum value of the preset zero-crossing current interval; and dead zone compensation of the permanent magnet motor by using a third compensation amount when the current feedback value is in the current zero-crossing point interval.

[0067] The further function description of each module is the same as that of the above-mentioned corresponding method embodiment, which will not be repeated here.

[0068] Based on the same inventive concept, the application also provides a permanent magnet motor system corresponding to any of the above-mentioned embodiment methods. The system comprises a permanent magnet motor and a permanent magnet motor dead zone compensator, and the permanent magnet motor dead zone compensator executes the permanent magnet motor dead zone compensation method in the above-mentioned embodiment.

[0069] The function description of the permanent magnet motor dead zone compensator is the same as that of the above-mentioned corresponding method embodiment, which will not be repeated here.

[0070] Based on the same inventive concept, the application also provides an electronic device, which comprises a memory, a processor and a computer program stored in the memory and executable on the processor, and the processor executes the program to implement the permanent magnet motor dead zone compensation method of any one of the embodiments.

[0071] Figure 4 A more specific electronic device hardware structure diagram provided by the embodiment is shown, which can include a processor 410, a memory 420, an input / output interface 430, a communication interface 440 and a bus 450. The processor 410, the memory 420, the input / output interface 430 and the communication interface 440 are connected to each other through the bus 450.

[0072] The processor 410 can be implemented by a general CPU (Central Processing Unit), a microprocessor, an ASIC (Application Specific Integrated Circuit), or one or more integrated circuits, etc., for executing related programs to implement the technical solutions provided by the embodiments of the present specification.

[0073] The memory 420 can be implemented by a ROM (Read Only Memory), a RAM (Random Access Memory), a static storage device, a dynamic storage device, etc. The memory 420 can store an operating system and other application programs, and when the technical solutions provided by the embodiments of the present specification are implemented by software or firmware, the related program codes are stored in the memory 420 and called and executed by the processor 410.

[0074] The input / output interface 430 is used to connect input / output modules to realize information input and output. The input / output modules can be configured as components in the device (not shown in the figure) or externally connected to the device to provide corresponding functions. The input device can include a keyboard, a mouse, a touch screen, a microphone, various sensors, etc., and the output device can include a display, a speaker, a vibrator, an indicator light, etc.

[0075] The communication interface 440 is used to connect a communication module (not shown in the figure) to realize the communication interaction between the device and other devices. The communication module can realize communication through a wired manner (such as USB, network cable, etc.) or a wireless manner (such as mobile network, WIFI, Bluetooth, etc.).

[0076] The bus 450 includes a channel for transmitting information between various components (such as the processor 410, the memory 420, the input / output interface 430 and the communication interface 440) of the device.

[0077] It should be noted that although the above device only shows the processor 410, the memory 420, the input / output interface 430, the communication interface 440 and the bus 450, in the specific implementation process, the device can also include other components necessary for normal operation. In addition, those skilled in the art can understand that the above device can also only contain the components necessary to implement the embodiments of the present application, and does not necessarily contain all the components shown in the figure.

[0078] The electronic device of the above embodiment is used to implement the corresponding permanent magnet motor dead zone compensation method in any of the preceding embodiments, and has the beneficial effects of the corresponding method embodiments, which are not repeated here.

[0079] Based on the same inventive concept, corresponding to the method of any of the above embodiments, the present application also provides a non-transitory computer readable storage medium storing computer instructions for causing the computer to execute the permanent magnet motor dead zone compensation method according to any of the above embodiments.

[0080] The computer readable medium of the present embodiment includes permanent and non-permanent, removable and non-removable media, which can be implemented by any method or technology to store information. The 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 technologies, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information accessible by a computing device.

[0081] The computer instructions stored in the storage medium of the above embodiment are used to cause the computer to execute the permanent magnet motor dead zone compensation method according to any of the above embodiments, and have the beneficial effects of the corresponding method embodiments, which are not repeated here.

[0082] Those skilled in the art should understand that the above discussion of any of the embodiments is only exemplary and is not intended to imply that the scope (including claims) of the present application is limited to these examples; under the idea of the present application, the above embodiments or technical features in different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes of different aspects of the embodiments of the present application as described above. In order to be brief, they are not provided in detail.

[0083] Additionally, to simplify the description and discussion, and so as not to obscure the embodiments of the application with details that are well known to those skilled in the art, some conventional attributes of integrated circuit (IC) chips and other components can or can not be shown in the drawings or discussed below. Furthermore, devices can be shown in block diagram form in order to avoid obscuring the embodiments of the application, and this also acknowledges the fact that substantial implementation-specific details can be incorporated into the full-scale, integrated, circuit- or microprocessor-implementation of these devices, where such specific details are well within the capabilities of those of ordinary skill in the art. Where specific details are set forth in order to describe an illustrative embodiment of the application, it will be apparent to one of ordinary skill in the art that the application can be practiced without, or with variations of, these specific details. The description is, therefore, not to be taken in a limited sense, and the scope of the inventive embodiments is defined by the appended claims.

[0084] Although the application has been described in conjunction with specific embodiments thereof, numerous alternatives, modifications, and variations will be readily apparent to those of ordinary skill in the art. For example, other memory architectures (e.g., dynamic RAM (DRAM)) can use the embodiments discussed.

[0085] It is to be understood that the above-described embodiments are merely illustrative of the principles of the present application, and that numerous and various modifications can be derived therefrom in light of the scope of the appended claims without departing from the scope of the application.

Claims

1. A dead-time compensation method for a permanent magnet motor, characterized by, The method comprises: obtaining a current feedback value and a current command value of a permanent magnet motor; determining the positive and negative polarity of the current feedback value according to the size relationship between the current feedback value and a preset zero-crossing current interval; when the current feedback value is in the positive half cycle of the current and the current command value is greater than the maximum value of the preset zero-crossing current interval, using a first compensation amount to compensate the dead zone of the permanent magnet motor; when the current feedback value is in the negative half cycle of the current and the current command value is less than the minimum value of the preset zero-crossing current interval, using a second compensation amount to compensate the dead zone of the permanent magnet motor; when the current feedback value is in the zero-crossing point interval of the current, using a third compensation amount to compensate the dead zone of the permanent magnet motor; wherein determining the positive and negative polarity of the current feedback value specifically comprises: if the current feedback value is greater than the maximum value of the preset zero-crossing current interval, the current feedback value is in the positive half cycle of the current; if the current feedback value is less than the minimum value of the preset zero-crossing current interval, the current feedback value is in the negative half cycle of the current; if the current feedback value is in the preset zero-crossing current interval, the current feedback value is in the zero-crossing point interval of the current; the first compensation amount, the second compensation amount and the third compensation amount are respectively: dx_1 = K Δu; dx_2 = -K Δu; dx_3 = K Δu1; wherein dx_1 is the first compensation amount, dx_2 is the second compensation amount, dx_3 is the third compensation amount, K is a compensation coefficient, K>0, Δu is a first dead zone compensation voltage amount, Δu≥0, Δu1 is a second dead zone compensation voltage amount, Δu1≥0; Δu is a preset fixed value, or Δu = k1 T1 U / T2; Δu1 is a preset fixed value, or Δu1 = k2 I cmd +k3 V1; Wherein, k1 is the derating factor, k1 is adjusted according to the current falling time when the power device in the permanent magnet motor is turned off; T1 is the dead time, U is the bus voltage, T2 is the modulation period of pulse width modulation to the permanent magnet motor; k2 is the attenuation coefficient; k3 is the proportional value, k3=V2 / I cmd , V2 is the tube voltage drop generated by the power device in the driver under I cmd ; k2>=0; I cmd is the current command value, V1 is the maximum tube voltage drop of the power device in the driver.

2. The dead-time compensation method of a permanent magnet motor according to claim 1, characterized by, The preset zero-crossing current interval is [-I cmdmin , I cmdmin ] , I cmdmin is: I cmdmin = (m2 / m1) I n Wherein, I cmdmin is the absolute value of the upper and lower limits of the preset zero-crossing current interval, m2 is the minimum zero-current interval judgment coefficient, I n is the rated current value of the driver driving the power device in the permanent magnet motor, and m1 is the internal current value calculation accuracy of the driver.

3. A dead-time compensation device for N-phase permanent magnet motor, N≥1, for compensating dead-time of the permanent magnet motor, characterized in that, the device comprises N single-phase dead zone compensation modules, which correspond one-to-one to N phases of the permanent magnet motor; the single-phase dead zone compensation module comprises a submodule for executing the operation steps of the method of any one of claims 1-2, for compensating the corresponding output phase current of the permanent magnet motor driver.

4. A permanent magnet electric machine system characterized by, The system comprises a permanent magnet motor and a permanent magnet motor dead zone compensator, and the permanent magnet motor dead zone compensator executes the method of any one of claims 1-2.

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