Motor driving method, device, apparatus and storage medium

Abstract

The application discloses a motor driving method, device, equipment and storage medium, and belongs to the technical field of motor control. The method comprises the following steps: acquiring a first switching frequency of a motor; determining a second switching frequency based on the first switching frequency, a frequency spread width and a frequency spread random number, wherein the frequency spread width indicates a variation range of the switching frequency, and the frequency spread random number is generated based on a linear congruential method; determining a first duty cycle according to a first switching period corresponding to the second switching frequency; and driving the motor through a first electric signal corresponding to the first duty cycle. The method disperses the sideband harmonic near the original fixed first switching frequency to more frequencies by using the randomly generated frequency spread random number, so that the voltage and current harmonic amplitudes near the original fixed first switching frequency are reduced, and the sideband noise is weakened.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to the technical field of motor control, and in particular, relate to a motor driving method, device, equipment and storage medium. BACKGROUND

[0002] In the technical field of motor control, a space vector pulse width modulation algorithm is used to drive a motor, which causes high-frequency sideband current harmonics near the switching frequency. The high-frequency sideband current harmonics cause high-frequency sideband noise, which reduces the user experience. Therefore, there is an urgent need for a motor driving method to reduce sideband noise. SUMMARY

[0003] Embodiments of the present application provide a motor driving method, device, equipment and storage medium to reduce sideband noise. The technical solution is as follows:

[0004] In one aspect, a motor driving method is provided, the method comprising:

[0005] obtaining a first switching frequency of a motor;

[0006] determining a second switching frequency based on the first switching frequency, a frequency spreading width and a frequency spreading random number, the frequency spreading width indicating a variation range of the switching frequency, and the frequency spreading random number being generated based on a linear congruential method;

[0007] determining a first duty cycle according to a first switching period corresponding to the second switching frequency;

[0008] driving the motor by a first electrical signal corresponding to the first duty cycle.

[0009] In one possible implementation, the determining the first duty cycle according to the first switching period corresponding to the second switching frequency comprises: determining the first duty cycle according to a second switching period, a second duty cycle of the second switching period and the first switching period based on a recursive relationship between the switching period and the duty cycle, the second switching period being an Nth switching period before the first switching period, and N being a positive integer.

[0010] In a possible implementation, before determining the first duty cycle according to the second switching period, the second duty cycle of the second switching period and the first switching period based on the recursive relationship of the switching period and the duty cycle, the method further includes: determining a first relationship, the first relationship indicating that an output total voltage at any time is a sum of output voltages at the any time of a plurality of switching periods, any switching period of the plurality of switching periods including an on time interval and an idle time interval, the output voltage in the on time interval being a voltage pulse amplitude, the output voltage in the idle time interval being zero, a ratio of the on time interval of the any switching period to the any switching period being a duty cycle of the any switching period; performing Fourier transform on the first relationship to obtain a second relationship, the second relationship indicating a mapping relationship between a plurality of frequencies and the output voltage, the Fourier transform being used to change time into frequency; and determining the recursive relationship according to the first relationship and the second relationship based on that the output voltage at the target frequency is zero.

[0011] In a possible implementation, the determining the recursive relationship according to the first relationship and the second relationship based on that the output voltage at the target frequency is zero includes: determining a third relationship according to the first relationship and the second relationship, the third relationship indicating a relationship among the Mth switching period, a duty cycle of the Mth switching period and the voltage value; and determining the recursive relationship based on that the voltage value at the target frequency is zero, the recursive relationship indicating a relationship among the Mth switching period, the duty cycle of the Mth switching period, the M+Nth switching period and the duty cycle of the M+Nth switching period, the output voltage at the target frequency being zero indicating that a first voltage and a second voltage are equal, the first voltage being a voltage corresponding to the Mth switching period and the duty cycle of the Mth switching period, the second voltage being a voltage corresponding to the M+Nth switching period and the duty cycle of the M+Nth switching period, the N being a positive integer.

[0012] In a possible implementation, the driving the motor by the first electrical signal corresponding to the first duty cycle includes: determining first electrical signals corresponding to three-phase voltages respectively driving the motor by the first duty cycle; and driving the motor based on the first electrical signals corresponding to the three-phase voltages respectively.

[0013] In a possible implementation, the determining the second switching frequency based on the first switching frequency, the frequency spreading width and the frequency spreading random number includes: determining that a sum of the first switching frequency and a frequency spreading frequency is the second switching frequency, the frequency spreading frequency being a product of the frequency spreading width and the frequency spreading random number.

[0014] In another aspect, an electric motor driving apparatus is also provided, and the apparatus includes:

[0015] an acquisition module configured to acquire a first switching frequency of a motor;

[0016] a first determination module configured to determine a second switching frequency based on the first switching frequency, a spread frequency width and a spread frequency random number, the spread frequency width indicating a variation range of the switching frequency, and the spread frequency random number being generated based on a linear congruential method;

[0017] a second determination module configured to determine a first duty cycle according to a first switching period corresponding to the second switching frequency;

[0018] a driving module configured to drive the motor by a first electrical signal corresponding to the first duty cycle.

[0019] In a possible implementation, the second determination module is configured to determine the first duty cycle according to a second switching period, a second duty cycle of the second switching period and the first switching period based on a recursive relationship between the switching period and the duty cycle, the second switching period being an Nth switching period before the first switching period, and N being a positive integer.

[0020] In a possible implementation, the apparatus further includes a third determination module configured to determine a first relationship, the first relationship indicating that an output total voltage at any time is a sum of output voltages of a plurality of switching periods at the any time, any switching period of the plurality of switching periods including an on time interval and an idle time interval, the output voltage in the on time interval being a voltage pulse amplitude, the output voltage in the idle time interval being zero, and a ratio of the on time interval of the any switching period to the any switching period being a duty cycle of the any switching period; a transformation module configured to perform Fourier transform on the first relationship to obtain a second relationship, the second relationship indicating a mapping relationship between a plurality of frequencies and the output voltage, the Fourier transform being used to change time into frequency; and the second determination module is configured to determine the recursive relationship according to the first relationship and the second relationship based on that the output voltage at a target frequency is zero.

[0021] In a possible implementation, the second determining module is configured to determine a third relationship according to the first relationship and the second relationship, the third relationship indicating a relationship among the Mth switching period, a duty cycle of the Mth switching period, and the voltage value; determine the recursive relationship based on the voltage value at the target frequency being zero, the recursive relationship indicating a relationship among the Mth switching period, a duty cycle of the Mth switching period, the M+Nth switching period, and a duty cycle of the M+Nth switching period, the output voltage at the target frequency being zero indicating that a first voltage and a second voltage are equal, the first voltage being a voltage corresponding to the Mth switching period and the duty cycle of the Mth switching period, the second voltage being a voltage corresponding to the M+Nth switching period and the duty cycle of the M+Nth switching period, and the N being a positive integer.

[0022] In a possible implementation, the driving module is configured to determine first electrical signals corresponding to the three-phase voltages respectively by the first duty cycle; and drive the motor based on the first electrical signals corresponding to the three-phase voltages respectively.

[0023] In a possible implementation, the first determining module is configured to determine that a sum of the first switching frequency and a spread frequency is the second switching frequency, the spread frequency being a product of the spread width and the spread random number.

[0024] In another aspect, a computer device is also provided, which includes a processor and a memory, and the memory stores at least one computer program, which is loaded and executed by the processor, so that the computer device implements the motor driving method in any of the above aspects.

[0025] In another aspect, a computer readable storage medium is also provided, which stores at least one computer program, which is loaded and executed by a processor, so that a computer implements the motor driving method in any of the above aspects.

[0026] In another aspect, a computer program product or a computer program is also provided, which includes computer instructions stored in a computer readable storage medium. A processor of a computer device reads the computer instructions from the computer readable storage medium, and the processor executes the computer instructions, so that the computer device executes the motor driving method in any of the above aspects.

[0027] The technical scheme provided by the embodiments of the present application at least brings the following beneficial effects:

[0028] The technical scheme provided in the application determines a random second switching frequency through a random frequency multiplication random number, thereby dispersing the side frequency harmonics near the original fixed first switching frequency to more frequencies, reducing the voltage and current harmonic amplitudes near the original fixed first switching frequency, and weakening the sideband noise. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0030] Figure 1 is a schematic diagram of an environment for implementing a motor driving method provided by an embodiment of the present application;

[0031] Figure 2 is a flowchart of a motor driving method provided by an embodiment of the present application;

[0032] Figure 3 is a schematic diagram of a duty cycle relationship provided by an embodiment of the present application;

[0033] Figure 4 is a schematic diagram of a spectrum comparison between random frequency modulation and standard frequency modulation provided by an embodiment of the present application;

[0034] Figure 5 is a schematic diagram of a motor driving scene provided by an embodiment of the present application;

[0035] Figure 6 is a structural schematic diagram of a motor driving device provided by an embodiment of the present application;

[0036] Figure 7 is a structural schematic diagram of a server provided by an embodiment of the present application;

[0037] Figure 8 is a structural schematic diagram of a terminal provided by an embodiment of the present application. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical scheme and advantages of the present application more clear, the embodiments of the present application will be further described in detail below with reference to the drawings.

[0039] It should be noted that the terms "first", "second", etc. (if any) in the specification of the present application are used to distinguish similar objects, and do not necessarily have to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. The implementation described in the following exemplary embodiments does not represent all implementations consistent with the present application. Instead, they are only examples of devices and methods consistent with some aspects of the present application.

[0040] In the field of motor control technology, space vector pulse width modulation (SVPWM) generates a sinusoidal pattern of voltage output by controlling the switching state of the inverter, thereby driving the motor. However, due to the characteristics of the SVPWM algorithm, high-frequency sideband current harmonics are generated near the switching frequency. High-frequency sideband current harmonics increase motor losses, reduce efficiency, and high-frequency sideband noise is formed, which reduces user experience.

[0041] The embodiments of the present application provide a motor driving method, which can reduce the probability of generating high-frequency sideband current harmonics near the switching frequency, i.e. reduce sideband noise. Please refer to Figure 1 which shows a schematic diagram of the motor driving method implementation environment provided by the embodiments of the present application. The implementation environment can include a terminal 11 and a vehicle 12, the terminal 11 and the vehicle 12 establish a communication connection through a wired or wireless network, and the vehicle 12 is installed with a motor.

[0042] Among them, the terminal 11 is located on the vehicle 12. The terminal 11 can obtain the first switching frequency of the motor of the vehicle 12, i.e. the switching frequency before adjustment, and the terminal 11 can spread the frequency of the obtained first switching frequency to obtain the second switching frequency randomly valued under the spread width, and then disperse the high-frequency sideband current harmonics generated near the switching frequency. Optionally, the terminal 11 can be a vehicle-mounted terminal capable of executing the method provided by the embodiments of the present application, for example, the terminal 11 can be a space vector pulse width modulation algorithm module of the vehicle 12.

[0043] In a possible implementation, the implementation environment further includes a server 13, which is in communication connection with the vehicle 12 and the terminal 11 respectively through a wired or wireless network. Optionally, the terminal 11 can send the acquired first switching frequency to the server 13, the server 13 acquires the second switching frequency based on the first switching frequency, and the server 13 sends the second switching frequency to the terminal 11, so that the terminal 11 can control the vehicle 12 based on the second switching frequency. In the embodiment of the application, the server 13 can be a vehicle server, or a server cluster composed of multiple vehicle servers, or a cloud computing service center.

[0044] Those skilled in the art should understand that the terminal 11, the vehicle 12, the motor of the vehicle 12 and the server 13 described above are only examples, and other existing or future terminals, vehicles or servers can also be applicable to the application and should be included in the protection scope of the application.

[0045] Referring to Figure 2 , Figure 2 A flowchart of a motor driving method provided by the embodiment of the application is shown. The method is described by taking a terminal as an example. For example, the terminal can be the terminal 11 shown in FIG. 1. As shown in FIG. 2, the motor driving method includes but is not limited to the following steps 201-204. Figure 1 Figure 2 The motor driving method includes but is not limited to the following steps 201-204.

[0046] Step 201: Acquire a first switching frequency of a motor.

[0047] The motor of the embodiment of the application is driven based on a space vector pulse width modulation algorithm, and the switching frequency in the space vector pulse width modulation refers to the switching frequency of an inverter switching device. The first switching frequency is a fixed switching frequency set by a user. The embodiment of the application does not limit the method for acquiring the first switching frequency of the motor, for example, the first switching frequency can be received by a user, or the first switching frequency in the inverter can be acquired by a sensor.

[0048] Step 202: Determine a second switching frequency based on the first switching frequency, a frequency spread width and a frequency spread random number. The frequency spread width indicates a variation range of the switching frequency, and the frequency spread random number is generated based on a linear congruential method.

[0049] The frequency spread width is a parameter indicating the variation range of the switching frequency, and it can also be said that the frequency spread width defines the possible value range of the second switching frequency. For example, if the first switching frequency is 10 kHz, the frequency spread width is 3 kHz, and the value range of the second switching frequency is 7 kHz to 13 kHz. The frequency spread random number serves as a factor or offset to determine which frequency point around the first switching frequency is taken as the second switching frequency. ​

[0050] In a possible implementation, the process of determining the second switching frequency based on the first switching frequency, the frequency hopping width and the frequency hopping random number comprises determining that the sum of the first switching frequency and a frequency hopping frequency is the second switching frequency, and the frequency hopping frequency is the product of the frequency hopping width and the frequency hopping random number. The random switching frequency f (i.e. the second switching frequency) can be expressed by Formula 1 as follows,

[0051] f = f s + RΔf (Formula 1)

[0052] wherein f s is the first switching frequency, Δf is the frequency hopping width, R is the frequency hopping random number, and RΔf is the frequency hopping frequency. The frequency hopping random number R ranges from -1 to 1.

[0053] The frequency hopping random number is generated by the microprocessor through a specific algorithm. The algorithm for generating the random number needs to meet the following conditions: the period of the random number is long enough to ensure that there is no statistical repetition when the system runs for a long time; the algorithm is simple, thereby reducing the burden of the microprocessor and the occupation of the memory space; and good statistical properties, including uniformity of distribution, sampling randomness and independence, etc. Optionally, the method for generating the frequency hopping random number can be a lookup table method or a linear congruential method. The lookup table method refers to pre-generating and storing a series of random numbers, and then directly reading when needed.

[0054] The method for generating the frequency hopping random number is taken as the linear congruential method in the embodiments of the present application. The linear congruential method generates random numbers through an iterative algorithm. The formula of the linear congruential method can be Formula 2 as follows,

[0055]

[0056] wherein N s indicates the word length of the random number, the longer the word length of the random number, the longer the period of the random number, R n is the n th random number, R n+1 is the n+1 th random number, i.e. the next random number is generated by iteration from the previous random number, a and b are constants, a is a multiplier for multiplying the current random number R n in each iteration, b is an increment for adding to the result of R n ·a in each iteration. 2 Ns is a modulus, which determines the output range of the random number generator, i.e. the value of R n will be between 0 and 2 Ns -1. Exemplarily, a can be 4k+1, k is a natural number, and b is prime to 2 Ns , so that any random number in a period will appear.

[0057] Optionally, the manner of generating the second switching frequency corresponding to the random frequency can be referred to as a random modulation strategy, that is, by randomizing the operating frequency of the switching element, the noise originally concentrated around the switching frequency is dispersed. So that the noise is no longer concentrated on a single frequency point, but distributed in a wider frequency range, and the noise intensity on the frequency point is reduced, thereby reducing the impact of noise on users.

[0058] In step 203, the first duty cycle is determined according to the first switching period corresponding to the second switching frequency.

[0059] The random modulation strategy disperses noise by randomizing the switching frequency, and in addition, for a specific frequency within the switching period, the current harmonic at the specific frequency can be eliminated or reduced by controlling the duty cycle. The duty cycle is used to describe the proportion of the duration of a specific state (such as high level or on state) in the entire period of a periodic signal. The second switching frequency generated based on step 202 is a random value, and the first switching period corresponding to the second switching frequency is also a random value. The switching period refers to the time occupied by a signal.

[0060] In one possible implementation, the process of determining the first duty cycle according to the first switching period corresponding to the second switching frequency includes determining the first duty cycle according to the second switching period, the second duty cycle of the second switching period, and the first switching period based on a recursive relationship between the switching period and the duty cycle, the second switching period being the Nth switching period before the first switching period, N being a positive integer.

[0061] In the embodiments of the present application, the recursive relationship indicates that the first duty cycle is determined based on the second switching period, the second duty cycle, and the first switching period corresponding to the first duty cycle. Among them, the second switching period and the second duty cycle correspond to a voltage of zero at the target frequency (i.e. the frequency that needs to be eliminated or weakened). The voltage of zero makes the current at the target frequency weaken, and thus the noise at the target frequency weakens. The recursive relationship is to determine the duty cycle in the current switching period based on the duty cycle in the previous switching period, so as to weaken the current at the target frequency in the current period.

[0062] The second switching period is the Nth switching period before the first switching period, N being a positive integer. For example, if N is 1, then the second switching period is the period immediately before the first switching period; if N is 2, then the second switching period is the second period before the first switching period.

[0063] In a possible implementation, before determining the first duty cycle according to the second switching period, the second duty cycle of the second switching period, and the first switching period, the method further includes: determining a first relationship, the first relationship indicating that a total output voltage at any time is a sum of output voltages at the any time in a plurality of switching periods, any switching period in the plurality of switching periods including an on-time interval and an idle-time interval, the output voltage in the on-time interval being a voltage pulse amplitude, the output voltage in the idle-time interval being zero, and a ratio of the on-time interval of the any switching period to the any switching period being a duty cycle of the any switching period; performing Fourier transform on the first relationship to obtain a second relationship, the second relationship indicating a mapping relationship between a plurality of frequencies and the output voltage, the Fourier transform being used to change time into frequency; and determining the recursive relationship according to the first relationship and the second relationship based on that the output voltage at the target frequency is zero.

[0064] In the on-time interval, the switch is in the on state, and the output voltage is the amplitude of the voltage pulse. In the idle-time interval, the switch is in the off state, and the output voltage is zero. The ratio of the on-time interval of any switching period to the entire switching period is the duty cycle of the switching period. The duty cycle determines the length of time that the switch is in the on state in each switching period. Referring to a duty cycle relationship diagram shown in FIG. 1, the duty cycle of the first switching period T1 is D1, the duty cycle of the second switching period T2 is D2, and the duty cycle of the third switching period T3 is D3. Figure 3 m T s m is the start time of the T m m is the end time of the T m+1 m is the start time of the T m+1 s is the end time of the T m+1 m+1 is the start time of the T m+1

[0065] m

[0066]

[0067] Figure 3 m s

[0068] ​​​​​​​​​​​​​​​The first relationship is subjected to Fourier transform to analyze the spectral characteristics of the switch period output signal. The Fourier transform is a method of converting a time domain signal into a frequency domain signal. The Fourier transform can decompose a complex waveform into a series of superimposed sine and cosine waves. Through the Fourier transform, a mapping relationship between multiple frequencies and voltages, i.e., a second relationship, can be obtained. The second relationship describes the voltage of the output signal at different frequencies, i.e., the spectral characteristics. By controlling the spectral characteristics of the output signal, the interference or noise at certain specific frequencies can be reduced.

[0069] Exemplarily, the second relationship can be as follows,

[0070]

[0071] wherein G(f) indicates the voltage at the frequency f, g(t) indicates the total output voltage, cos indicates the cosine function, and sin indicates the sine function. The voltage at the target frequency f0 is zero, i.e., the harmonic at the target frequency is eliminated or weakened. Based on the target frequency f0 and the voltage G(f0) = 0, the recursive relationship can be determined in combination with the above formula 3 and formula 4. Embodiments of the present application do not limit the process of deriving the recursive relationship in combination with formula 3 and formula 4.

[0072] In a possible implementation, the process of deriving the recursive relationship in combination with formula 3 and formula 4 includes determining a third relationship according to the first relationship and the second relationship, the third relationship indicating the relationship of the Mth switch period, the duty cycle of the Mth switch period, and the voltage value; determining the recursive relationship based on the voltage value at the target frequency being zero, the recursive relationship indicating the relationship of the Mth switch period, the duty cycle of the Mth switch period, the M+Nth switch period, and the duty cycle of the M+Nth switch period, the voltage at the target frequency being zero indicating that the first voltage and the second voltage are equal, the first voltage being the voltage corresponding to the Mth switch period and the duty cycle of the Mth switch period, the second voltage being the voltage corresponding to the M+Nth switch period and the duty cycle of the M+Nth switch period, and N being a positive integer.

[0073] Based on the above content, the target frequency f0 and the voltage G(f0) = 0, i.e., the real part and the imaginary part of formula 4 are both 0, the following formula 5 is obtained,

[0074]

[0075] Based on formula 5, the following formula 6 can be determined,

[0076]

[0077] Bringing formula 3 into formula 6, the following formula 7, i.e., the third relationship, can be obtained,

[0078]

[0079] wherein A is the voltage amplitude, ω0is the angular frequency corresponding to the frequency f0, The angle indicating the deviation of the function from the equilibrium position. If c(f0) = 0, i.e. the voltage at the target frequency is zero, c(f0) = 0 is brought into equation 7 to obtain the following equation 8,

[0080]

[0081] The recurrence relation describes how the duty cycle of the next switching period is calculated from the duty cycle of the current switching period. Exemplarily, the recurrence relation indicates the relationship between the Mth switching period, the duty cycle of the Mth switching period, the M+Nth switching period and the duty cycle of the M+Nth switching period.

[0082] In the frequency domain analysis, each frequency corresponds to a voltage value. The first voltage value refers to the voltage value corresponding to the Mth switching period and its duty cycle, while the second voltage value is the voltage value corresponding to the M+Nth switching period and its duty cycle. When the voltage value at the target frequency is zero, i.e. at this frequency, the sum of the sine and cosine components of the output signal is zero. That is, the first voltage value and the second voltage value are equal but opposite in sign, thus canceling each other out, so that the entire voltage value is zero.

[0083] Thus, based on equation 8, the following equation 9 can be obtained,

[0084]

[0085] Simplifying equation 9 gives the recurrence relation, i.e. equation 10,

[0086]

[0087] Based on this equation 10, the first duty cycle D m , the second duty cycle D m of the second switching period T m+n and the first switching period T m+n .

[0088] Referring to Figure 4 , a random frequency modulation and a standard frequency modulation spectrum comparison diagram is shown, wherein the standard frequency modulation is that the first duty cycle is not re-determined, at this time, there are multiple high currents at the target frequency, i.e. multiple noises, and through the re-determined first duty cycle, the spectrum diagram under the random frequency modulation can be obtained, it can be seen that the multiple high currents at the target frequency are dispersed to multiple other frequencies, so that the current at the target frequency is weakened, thereby reducing the noise.

[0089] In step 204, the motor is driven by the first electrical signal corresponding to the first duty cycle.

[0090] In motor control, duty cycle is typically used to control the average power or speed of the motor. The first electrical signal is generated based on the first duty cycle. The first electrical signal is divided into two parts in time: a high level and a low level. The ratio of the duration of the high level to the entire signal period is the duty cycle.

[0091] In one possible implementation, the process of driving the motor with the first electrical signal corresponding to the first duty cycle includes determining the first electrical signal corresponding to each of the three phase voltages of the motor using the first duty cycle; and driving the motor based on the first electrical signal corresponding to each of the three phase voltages.

[0092] The motor requires three-phase voltage to drive it, with a phase difference of 120 degrees between the three phases. In the motor control system, the amplitude and phase of the three-phase voltage can be precisely adjusted by the controller. A corresponding first electrical signal is generated for each phase voltage. Given the first electrical signals corresponding to each of the three phase voltages, the motor is driven based on these signals.

[0093] For ease of understanding, this application provides a motor-driven scenario in its embodiments; see [link to relevant documentation]. Figure 5 MTPA (Maximum Torque Per Ampere) is based on the T (Torque) output current reference value (i*). q i* d The current regulator (PI, Proportional-Integral) receives the dq-axis current reference value (i*). q i* d ) and actual value (i q i d The reference value of the dq-axis voltage (u*) is calculated using a PI converter. q u* d The Park inverse transform converts the dq-axis voltage reference value (u*). q u* d Converting to voltage in a two-phase stationary coordinate system (u*) α u* β Park refers to a specific coordinate transformation method. Space vector pulse width modulation is based on (u* α u* β The inverter calculates the switching time of the inverter bridge arms and generates a PWM (Pulse Width Modulation) signal. The inverter then uses the PWM signal to adjust the DC voltage U... dc The current is converted to three-phase AC to drive the motor. Three-phase current is collected by sensors and converted into dq-axis current (i) through Clarke and Park transformations.q d ), and input to the current regulator, wherein the Clarke transformation is a mathematical method of converting variables (i a b ) in three-phase stationary coordinate system into variables (i α β ) in two-phase stationary coordinate system, and the Park transformation converts variables in two-phase stationary coordinate system into dq-axis currents (iq, id). In addition, the position signal θ of the motor can be obtained through position detection / angle calculation, which can be used by the controller to determine the current position of the motor, so as to realize accurate control of the motor movement through adjustment of the voltage, wherein the motor in the formula (1) is a PMSM (Permanent-Magnet Synchronous Motor). Figure 5

[0094] In summary, the motor driving method provided by the embodiments of the present application determines a random second switching frequency through a randomly generated frequency-spreading random number, so as to disperse the side frequency harmonics near the original fixed first switching frequency to more frequencies, so that the voltage and current harmonic amplitudes near the original fixed first switching frequency are reduced, thereby weakening the vibration noise.

[0095] Referring to Figure 6 , Figure 6 FIG. 1 is a structural schematic diagram of a motor driving device provided by an embodiment of the present application, as shown in the figure, the device comprises: Figure 6 The acquisition module 601 is configured to acquire a first switching frequency of the motor.

[0096] The first determination module 602 is configured to determine a second switching frequency based on the first switching frequency, a frequency-spreading width, and a frequency-spreading random number, wherein the frequency-spreading width indicates a variation range of the switching frequency, and the frequency-spreading random number is generated based on a linear congruential method.

[0097] The second determination module 603 is configured to determine a first duty cycle according to a first switching period corresponding to the second switching frequency.

[0098] The driving module 604 is configured to drive the motor through a first electrical signal corresponding to the first duty cycle.

[0099] In a possible implementation, the second determination module 603 is configured to determine the first duty cycle according to the second switching period, a second duty cycle of the second switching period, and the first switching period based on a recursive relationship between the switching period and the duty cycle, wherein the second switching period is an Nth switching period before the first switching period, and N is a positive integer.

[0100]

[0101] ​​​​​In a possible implementation, the apparatus further includes: a third determination module configured to determine a first relationship, the first relationship indicating that an output total voltage at any time is a sum of output voltages at any time in a plurality of switching periods, any switching period in the plurality of switching periods including an on time interval and an idle time interval, the output voltage in the on time interval being a voltage pulse amplitude, the output voltage in the idle time interval being zero, a ratio of the on time interval of any switching period to any switching period being a duty cycle of any switching period; a transformation module configured to perform Fourier transform on the first relationship to obtain a second relationship, the second relationship indicating a mapping relationship between a plurality of frequencies and the output voltage, the Fourier transform being used to change time into frequency; and a second determination module 603 configured to determine a recursive relationship based on the output voltage at the target frequency being zero and the first relationship and the second relationship.

[0102] In a possible implementation, the second determination module 603 is configured to determine a third relationship based on the first relationship and the second relationship, the third relationship indicating a relationship among an Mth switching period, a duty cycle of the Mth switching period, and a voltage value; and determine the recursive relationship based on the voltage value at the target frequency being zero, the recursive relationship indicating a relationship among the Mth switching period, the duty cycle of the Mth switching period, an M+Nth switching period, and a duty cycle of the M+Nth switching period, the output voltage at the target frequency being zero indicating that a first voltage and a second voltage are equal, the first voltage being a voltage corresponding to the Mth switching period and the duty cycle of the Mth switching period, the second voltage being a voltage corresponding to the M+Nth switching period and the duty cycle of the M+Nth switching period, and N being a positive integer.

[0103] In a possible implementation, the driving module 604 is configured to determine first electrical signals corresponding to three-phase voltages of the motor respectively by the first duty cycle; and drive the motor based on the first electrical signals corresponding to the three-phase voltages respectively.

[0104] In a possible implementation, the first determination module 602 is configured to determine that a sum of the first switching frequency and a spread frequency is a second switching frequency, the spread frequency being a product of a spread width and a spread random number.

[0105] To sum up, the motor driving apparatus provided by the embodiment of the present application determines the random second switching frequency by using the spread random number generated randomly, so that the side frequency harmonics near the original fixed first switching frequency are dispersed to more frequencies, the voltage and current harmonic amplitudes near the original fixed first switching frequency are reduced, and the vibration noise is weakened.

[0106] It should be noted that the above Figure 6The motor driving apparatus provided by the embodiments is only exemplified by the above-mentioned division of the functional modules in realizing its functions, and in actual functions, the above-mentioned functions can be completed by different functional modules according to needs, that is, the internal structure of the apparatus is divided into different functional modules to complete all or part of the above-mentioned functions. In addition, the apparatus and method embodiments provided by the above-mentioned embodiments belong to the same concept, and the specific implementation process can be seen from the method embodiments.

[0107] Figure 7 is a structural schematic diagram of a server provided by an embodiment of the present application. The server can be quite different in configuration or performance, and can include one or more processors 701 and one or more memories 702, wherein the one or more memories 702 store at least one computer program, the at least one computer program is loaded and executed by the one or more processors 701, so that the server implements the motor driving method provided by each method embodiment described above. Of course, the server can also have a wired or wireless network interface, a keyboard, an input and output interface and other components for realizing the functions of the apparatus, so as to perform input and output. The server can also include other components for realizing the functions of the apparatus, which will not be described here.

[0108] Figure 8 is a structural schematic diagram of a terminal provided by an embodiment of the present application, so that the terminal implements the motor driving method provided by each method embodiment described above. The terminal can be, for example: a vehicle-mounted terminal, a smart phone, a tablet computer, a player, a notebook computer or a desktop computer. The terminal can also be referred to as user equipment, a portable terminal, a laptop terminal, a desktop terminal and other names.

[0109] Generally, the terminal includes a processor 801 and a memory 802.

[0110] The processor 801 can include one or more processing cores, such as a 4-core processor, an 8-core processor, and the like. The processor 801 can be implemented in the form of at least one of a DSP (Digital Signal Processing), an FPGA (Field-Programmable Gate Array), a PLA (Programmable Logic Array). The processor 801 can also include a main processor and a coprocessor. The main processor is a processor for processing data in an awake state, also known as a CPU (Central Processing Unit). The coprocessor is a low-power processor for processing data in a standby state. In some embodiments, the processor 801 can be integrated with a GPU (Graphics Processing Unit) for rendering and drawing content required to be displayed by the display screen. In some embodiments, the processor 801 can further include an AI (Artificial Intelligence) processor for processing machine learning related computing operations.

[0111] The memory 802 can include one or more computer-readable storage media, which can be non-transitory. The memory 802 can also include a high-speed random access memory, and a nonvolatile memory such as one or more disk storage devices, flash storage devices. In some embodiments, the non-transitory computer-readable storage medium in the memory 802 is used to store at least one instruction for being executed by the processor 801 to enable the terminal to implement the motor driving method provided by the method embodiment of the present application.

[0112] In some embodiments, the terminal can also optionally include a peripheral device interface 803 and at least one peripheral device. The processor 801, the memory 802, and the peripheral device interface 803 can be connected through a bus or a signal line. Each peripheral device can be connected to the peripheral device interface 803 through a bus, a signal line, or a circuit board. Specifically, the peripheral device includes at least one of a radio frequency circuit 804, a display screen 805, a camera assembly 806, an audio circuit 807, and a power supply 808.

[0113] The peripheral interface 803 can be used to connect at least one I / O (Input / Output) related peripheral device to the processor 801 and the memory 802. In some embodiments, the processor 801, the memory 802 and the peripheral interface 803 are integrated on the same chip or circuit board; in some other embodiments, any one or two of the processor 801, the memory 802 and the peripheral interface 803 can be implemented on a separate chip or circuit board, and the present embodiments are not limited to this.

[0114] The radio frequency circuit 804 is used to receive and send RF (Radio Frequency) signals, also known as electromagnetic signals. The radio frequency circuit 804 communicates with a communication network and other communication devices through electromagnetic signals. The radio frequency circuit 804 converts electrical signals into electromagnetic signals for transmission, or converts received electromagnetic signals into electrical signals. Optionally, the radio frequency circuit 804 includes an antenna system, an RF transceiver, one or more amplifiers, a tuner, an oscillator, a digital signal processor, a codec chipset, a subscriber identity module card, and the like. The radio frequency circuit 804 can communicate with other terminals through at least one wireless communication protocol. The wireless communication protocol includes but is not limited to: a metropolitan area network, various generations of mobile communication networks (2G, 3G, 4G and 5G), a wireless local area network and / or a WiFi (Wireless Fidelity) network. In some embodiments, the radio frequency circuit 804 can also include NFC (Near Field Communication) related circuit, and the present application is not limited to this.

[0115] The display screen 805 is configured to display a UI (User Interface). The UI can include graphics, text, icons, video, and any combination thereof. When the display screen 805 is a touch display screen, the display screen 805 is further configured to capture touch signals on or above the surface of the display screen 805. The touch signals can be input to the processor 801 as control signals for processing. In this case, the display screen 805 can also be configured to provide virtual buttons and / or virtual keyboard, also known as soft buttons and / or soft keyboard. In some embodiments, the display screen 805 can be one, disposed on the front panel of the terminal; in other embodiments, the display screen 805 can be at least two, respectively disposed on different surfaces of the terminal or in a folding design; in other embodiments, the display screen 805 can be a flexible display screen, disposed on a curved surface or a folding surface of the terminal. Even, the display screen 805 can also be disposed in an irregular shape, i.e., a special-shaped screen. The display screen 805 can be made of LCD (Liquid Crystal Display), OLED (Organic Light-Emitting Diode), etc.

[0116] The camera assembly 806 is configured to capture images or videos. Optionally, the camera assembly 806 includes a front camera and a rear camera. Typically, the front camera is disposed on the front panel of the terminal, and the rear camera is disposed on the back of the terminal. In some embodiments, the rear camera is at least two, which are any one of a main camera, a depth-of-field camera, a wide-angle camera, and a telephoto camera, to realize the background blur function by fusing the main camera and the depth-of-field camera, the panoramic shooting and VR (Virtual Reality) shooting function by fusing the main camera and the wide-angle camera, or other fusion shooting functions. In some embodiments, the camera assembly 806 can further include a flash. The flash can be a single-color temperature flash or a dual-color temperature flash. The dual-color temperature flash refers to the combination of a warm light flash and a cold light flash, which can be used for light compensation under different color temperatures.

[0117] The audio circuit 807 can include a microphone and a speaker. The microphone is used to collect sound waves of the user and the environment, and convert the sound waves into an electrical signal input to the processor 801 for processing, or input to the radio frequency circuit 804 to realize voice communication. For the purpose of stereo sound collection or noise reduction, the microphone can be multiple, respectively arranged at different parts of the terminal. The microphone can also be an array microphone or an omnidirectional collection type microphone. The speaker is used to convert the electrical signal from the processor 801 or the radio frequency circuit 804 into sound waves. The speaker can be a traditional diaphragm speaker, or a piezoelectric ceramic speaker. When the speaker is a piezoelectric ceramic speaker, not only can it convert electrical signals into sound waves that humans can hear, but it can also convert electrical signals into sound waves that humans cannot hear for ranging purposes. In some embodiments, the audio circuit 807 can also include a headphone jack.

[0118] The power supply 808 is used to supply power to each component in the terminal. The power supply 808 can be alternating current, direct current, disposable battery or rechargeable battery. When the power supply 808 includes a rechargeable battery, the rechargeable battery can support wired charging or wireless charging. The rechargeable battery can also be used to support fast charging technology.

[0119] In some embodiments, the terminal also includes one or more sensors 809. The one or more sensors 809 include, but are not limited to, an acceleration sensor 810, a gyroscope sensor 811, a pressure sensor 812, an optical sensor 813, and a proximity sensor 814.

[0120] The acceleration sensor 810 can detect the acceleration in three coordinate axes of the coordinate system established by the terminal. For example, the acceleration sensor 810 can be used to detect the components of gravitational acceleration in three coordinate axes. The processor 801 can control the display screen 805 to display the user interface in a landscape view or a portrait view according to the gravitational acceleration signal collected by the acceleration sensor 810. The acceleration sensor 810 can also be used for game or user motion data collection.

[0121] The gyroscope sensor 811 can detect the body orientation and rotation angle of the terminal. The gyroscope sensor 811 can cooperate with the acceleration sensor 810 to collect 3D actions of the user on the terminal. The processor 801 can realize the following functions according to the data collected by the gyroscope sensor 811: motion sensing (such as changing the UI according to the user's tilt operation), image stabilization when shooting, game control, and inertial navigation.

[0122] The pressure sensor 812 can be disposed at the side frame of the terminal and / or the lower layer of the display screen 805. When the pressure sensor 812 is disposed at the side frame of the terminal, the holding signal of the user to the terminal can be detected, and the left-hand or right-hand recognition or shortcut operation can be performed by the processor 801 according to the holding signal collected by the pressure sensor 812. When the pressure sensor 812 is disposed at the lower layer of the display screen 805, the operable control on the UI interface can be controlled by the processor 801 according to the pressure operation of the user to the display screen 805. The operable control includes at least one of the button control, the scroll bar control, the icon control and the menu control.

[0123] The optical sensor 813 is configured to collect the ambient light intensity. In an embodiment, the processor 801 can control the display brightness of the display screen 805 according to the ambient light intensity collected by the optical sensor 813. Specifically, when the ambient light intensity is high, the display brightness of the display screen 805 is increased; and when the ambient light intensity is low, the display brightness of the display screen 805 is decreased. In another embodiment, the processor 801 can also dynamically adjust the shooting parameter of the camera assembly 806 according to the ambient light intensity collected by the optical sensor 813.

[0124] The proximity sensor 814, also referred to as the distance sensor, is usually disposed at the front panel of the terminal. The proximity sensor 814 is configured to collect the distance between the user and the front of the terminal. In an embodiment, when the proximity sensor 814 detects that the distance between the user and the front of the terminal gradually decreases, the processor 801 controls the display screen 805 to switch from the bright screen state to the screen-off state; and when the proximity sensor 814 detects that the distance between the user and the front of the terminal gradually increases, the processor 801 controls the display screen 805 to switch from the screen-off state to the bright screen state.

[0125] Those skilled in the art can understand that the structure shown in the above embodiments does not constitute a limitation on the terminal, and the terminal can include more or fewer components than those shown in the figures, or combine certain components, or adopt a different component arrangement. Figure 8 Those skilled in the art can understand that the structure shown in the above embodiments does not constitute a limitation on the terminal, and the terminal can include more or fewer components than those shown in the figures, or combine certain components, or adopt a different component arrangement.

[0126] In an example embodiment, a computer device is also provided, which includes a processor and a memory having at least one computer program stored therein. The at least one computer program is loaded and executed by one or more processors to enable the computer device to implement any of the above motor drive methods.

[0127] In an example embodiment, a computer readable storage medium is also provided, which stores at least one computer program. The at least one computer program is loaded and executed by the processor of the computer device to enable the computer to implement any of the above motor drive methods.

[0128] In a possible implementation manner, the computer readable storage medium can be a read-only memory (ROM), a random access memory (RAM), a compact disc read-only memory (CD-ROM), a magnetic tape, a floppy disk, an optical data storage device, or the like. Alternatively, the computer readable storage medium can be a non-transitory computer readable storage medium.

[0129] In an example embodiment, a computer program product or computer program including computer instructions stored in a computer readable storage medium is also provided. A processor of a computer device reads the computer instructions from the computer readable storage medium, and the processor executes the computer instructions to cause the computer device to perform any of the motor drive methods described above.

[0130] It should be noted that the information (including but not limited to user device information, user personal information, etc.), data (including but not limited to data for analysis, stored data, displayed data, etc.) and signals involved in the present application are all authorized by the user or fully authorized by all parties, and the collection, use and processing of related data need to comply with relevant laws, regulations and standards of relevant countries and regions. For example, the switching frequency involved in the present application is obtained under sufficient authorization.

[0131] It should be understood that "multiple" referred to herein refers to two or more. The "and / or" describes the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B can represent: A exists alone, A and B exist together, and B exists alone. The character " / " generally represents that the associated objects before and after it are in an "or" relationship.

[0132] The above only describes example embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method of driving an electric machine, characterized by, The method comprises: obtaining a first switching frequency of a motor; determining that a sum of the first switching frequency and a spread frequency is a second switching frequency, the spread frequency being a product of a spread width and a spread random number, the spread width indicating a variation range of the switching frequency, and the spread random number being generated based on a linear congruential method; determining, based on a recursive relationship of a switching period and a duty cycle, a first duty cycle of a first switching period according to a second switching period, a second duty cycle of the second switching period, and a first switching period corresponding to the second switching frequency, the second switching period being an Nth switching period before the first switching period, and N being a positive integer; driving the motor by a first electrical signal corresponding to the first duty cycle; wherein the recursive relationship indicates a relationship of an Mth switching period, a duty cycle of the Mth switching period, an M+Nth switching period, and a duty cycle of the M+Nth switching period, and the recursive relationship is obtained in the following manner: determining a first relationship indicating that an output total voltage at any time is a sum of output voltages of a plurality of switching periods at the any time, any switching period of the plurality of switching periods comprising an on-time interval and an idle-time interval, an output voltage in the on-time interval being a voltage pulse amplitude, an output voltage in the idle-time interval being zero, and a ratio of the on-time interval of the any switching period to the any switching period being a duty cycle of the any switching period; performing Fourier transform on the first relationship to obtain a second relationship indicating a mapping relationship of a plurality of frequencies and output voltages, the Fourier transform being used to convert a time-domain signal into a frequency-domain signal; determining a third relationship indicating a relationship of the Mth switching period, the duty cycle of the Mth switching period, and an output voltage at a target frequency according to the first relationship and the second relationship; determining the recursive relationship based on the output voltage at the target frequency being zero, the output voltage at the target frequency being zero indicating that a first voltage and a second voltage are equal, the first voltage being a voltage corresponding to the Mth switching period and the duty cycle of the Mth switching period, and the second voltage being a voltage corresponding to the M+Nth switching period and the duty cycle of the M+Nth switching period.

2. The method of claim 1, wherein, The driving of the motor by the first electrical signal corresponding to the first duty cycle comprises: determining, by the first duty cycle, first electrical signals corresponding to three-phase voltages for driving the motor; driving the motor based on the first electrical signals corresponding to the three-phase voltages.

3. An electric motor drive apparatus characterized by comprising: The apparatus comprises: an obtaining module configured to obtain a first switching frequency of a motor; a first determining module configured to determine that a sum of the first switching frequency and a spread frequency is a second switching frequency, the spread frequency being a product of a spread width and a spread random number, the spread width indicating a variation range of the switching frequency, and the spread random number being generated based on a linear congruential method; The second determining module is configured to determine, according to the second switching period, the second duty cycle of the second switching period, and the first switching period corresponding to the second switching frequency, a first duty cycle of the first switching period based on a recursive relationship of the switching period and the duty cycle, the second switching period being an Nth switching period before the first switching period, N being a positive integer; The driving module is configured to drive the motor by a first electrical signal corresponding to the first duty cycle. The recursive relationship indicates a relationship of an Mth switching period, a duty cycle of the Mth switching period, an M+Nth switching period, and a duty cycle of the M+Nth switching period, and the device further comprises: The third determining module is configured to determine a first relationship, the first relationship indicating that an output total voltage at any moment is a sum of output voltages of a plurality of switching periods at the any moment, any switching period of the plurality of switching periods including an on-time interval and an idle-time interval, the output voltage in the on-time interval being a voltage pulse amplitude, the output voltage in the idle-time interval being zero, and a ratio of the on-time interval of the any switching period to the any switching period being a duty cycle of the any switching period; The transforming module is configured to perform Fourier transform on the first relationship to obtain a second relationship, the second relationship indicating a mapping relationship of a plurality of frequencies and output voltages, the Fourier transform being used to convert a time-domain signal into a frequency-domain signal; The second determining module is further configured to determine a third relationship according to the first relationship and the second relationship, the third relationship indicating a relationship of the Mth switching period, the duty cycle of the Mth switching period, and an output voltage at a target frequency; determine the recursive relationship based on the output voltage at the target frequency being zero, the output voltage at the target frequency being zero indicating that a first voltage and a second voltage are equal, the first voltage being a voltage corresponding to the Mth switching period and the duty cycle of the Mth switching period, and the second voltage being a voltage corresponding to the M+Nth switching period and the duty cycle of the M+Nth switching period.

4. A computer device, comprising: The computer device includes a processor and a memory, and the memory stores at least one computer program, the at least one computer program is loaded and executed by the processor, so that the computer device implements the motor driving method of claim 1 or 2.

5. A computer readable storage medium, characterized in that, The computer readable storage medium stores at least one computer program, and the at least one computer program is loaded and executed by the processor, so that the computer implements the motor driving method of claim 1 or 2.

6. A computer program product, characterised in that, The computer program product comprises computer program code, and the computer program code is loaded and executed by the computer, so that the computer implements the motor driving method of claim 1 or 2.

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