Motor control method, storage medium and air conditioner

Abstract

The embodiments of the present application provide a motor control method, a storage medium and an air conditioner, and relate to the field of motor control technology. When a symmetrical waveform PWM signal does not meet the time required for current sampling, a PWM signal with a sampling segment is generated, and the sampling segment has two different non-zero vectors for sampling. The PWM waveform does not require phase shifting, and the algorithm is simple; when a symmetrical waveform PWM signal meets the time required for current sampling, a symmetrical waveform PWM signal is directly generated, and the algorithm is further simplified; the sampling segment is after the pulse width control segment, and can timely and accurately sample the current of the current control cycle, providing a more reliable calculation basis for the next control cycle.

Description

Technical Field

[0001] The present application relates to the technical field of motor control, and in particular to a motor control method, a storage medium and an air conditioner. Background Art

[0002] In the control of permanent magnet synchronous motor (PMSM), there are two current sampling methods: dual resistor sampling and single resistor sampling. When using single resistor sampling, the following conditions must be met:

[0003] Sampling times: sampling twice in one control cycle;

[0004] The vectors obtained by the two samplings are different non-zero vectors (000 and 111 are zero vectors, and other combinations are non-zero vectors).

[0005] Only sampling that meets the above conditions can obtain two-phase currents in the three-phase system. Finally, the third-phase current is calculated according to the relationship Iu+Iv+Iw=0, where Iu represents the U-phase current, Iv represents the V-phase current, and Iw represents the W-phase current.

[0006] For example Figure 1 , sampling once in the duration of 001 and 011 respectively, the three-phase current can be obtained. The vector of the time period indicated by t2 or t6 is 001, and the vector of the time period indicated by t3 or t5 is 011. Sampling once at one of t2 or t6, and sampling once at one of t3 or t5, the three-phase current can be obtained. The time period vector indicated by t1, t4 and t7 is a zero vector.

[0007] Since the change and stabilization of current requires a certain amount of time, there is a minimum value Tmin for the duration of the non-zero vector during single resistor sampling. When the actual time is less than the minimum value, the true and accurate current cannot be sampled. This minimum value is usually called the sampling window time.

[0008] For example Figure 1 , when sampling is selected between t2 and t3, if t3<Tmin, accurate current cannot be sampled within t3. For this problem, the current common method is to perform phase shifting, that is, to move the V phase pulse width to the left when generating the PWM signal, and to move the W phase to the left when necessary. However, different control cycles may require phase shifting, some may not, some may only need to move one phase, and some may need to move two or even three phases. This requires judgment in each cycle, and the algorithm complexity is relatively high. At the same time, frequent phase shifting will also increase the distortion of the three-phase output voltage, resulting in unstable motor operation or generating large electromagnetic noise, making single-resistance sampling difficult to apply to scenarios with high noise requirements.

[0009] In addition to phase shifting, another way is to generate appropriate PWM pulses, which can sample the real and accurate current without phase shifting of the PWM waveform, such as Figure 2 , fix the left side sampling, generate two different non-zero vectors on the left side, and each non-zero vector has enough sampling time to accommodate two samplings of sampling point 1 and sampling point 2, and the voltage size is controlled by the high level time D1, D2, and D3 of the pulse width control part on the right side.

[0010] However, this method has a problem. Since the sampling point of the current cycle is after the pulse width control part of the previous cycle, the sampling result actually reflects the pulse width control part of the previous cycle. Therefore, the sampled current is relatively lagging and lacks accuracy.

[0011] How to generate appropriate PWM pulses so that the current can be sampled more timely and accurately without the need for phase shifting of the PWM waveform is a technical problem that needs to be solved. Summary of the invention

[0012] The purpose of the present application is to provide a motor control method, a storage medium and an air conditioner to generate appropriate PWM pulses, which can sample current more timely and accurately when the PWM waveform does not require phase shifting.

[0013] To achieve the above objectives, the embodiments of the present application adopt the following technical solutions.

[0014] In a first aspect, an embodiment of the present application provides a motor control method, comprising:

[0015] Obtain the total high level duration of each phase control waveform in the current control cycle;

[0016] According to the difference between the total durations of the high levels of the three-phase control waveforms and the preset sampling window duration, a waveform mode of the three-phase PWM is selected, and a three-phase PWM signal is generated according to the waveform mode of the three-phase PWM;

[0017] The motor is controlled according to the three-phase PWM signal, and the three-phase current of the motor is sampled; the three-phase current is used to determine the total duration of the high level of each phase control waveform in the next control cycle;

[0018] The three-phase PWM waveform mode includes mode 1 and mode 2;

[0019] The waveform of the first mode satisfies: the high level of each phase control waveform is located in the middle of the control cycle, and the PWM signal waveform is symmetrical in the control cycle;

[0020] The waveform of the second mode satisfies: each control cycle of each phase control waveform includes a pulse width control section and a sampling section, the pulse width control section is before the sampling section, the sampling section of each phase control waveform includes a first sampling section and a second sampling section, the duration of the first sampling section and the second sampling section are both greater than or equal to the sampling window duration, the first sampling sections of the three-phase control waveforms are combined into a first vector, the second sampling sections of the three-phase control waveforms are combined into a second vector, the first vector and the second vector are non-zero vectors, the first vector and the second vector are different, and the high level duration in the pulse width control section of each phase control waveform is the total high level duration of the phase control waveform minus the high level duration of the sampling section of the phase control waveform;

[0021] In the process of controlling the motor according to the three-phase PWM signal generated by the second method, the step of sampling the three-phase current of the motor includes: completing the first current sampling during the time period of the first sampling segment, and completing the second current sampling during the time period of the second sampling segment; obtaining the three-phase current of the motor based on the first current sampling and the second current sampling.

[0022] Optionally, according to the difference between the total durations of the high levels of the three-phase control waveforms and a preset sampling window duration, the step of selecting a waveform mode of the three-phase PWM includes:

[0023] The total high-level duration of the three-phase control waveform in the current control cycle is arranged from long to short as T3>T2>T1. According to the formula t2=(T3-T2) / 2, t3=(T2-T1) / 2, the first duration t2 and the second duration t3 are calculated;

[0024] When the first time length is greater than or equal to the sampling window time length, and the second time length is greater than or equal to the sampling window time length, the waveform mode of the three-phase PWM is selected as mode 1;

[0025] When the first time length is shorter than the sampling window time length, or the second time length is shorter than the sampling window time length, the waveform mode of the three-phase PWM is selected as mode 2.

[0026] Optionally, when the sampling segments of a phase control waveform are all low level, the high level in the pulse width control segment of the phase control waveform is located at the leftmost or rightmost part of the pulse width control segment of the phase control waveform;

[0027] When the sampling segments of a phase control waveform are all high level, the high level in the pulse width control segment of the phase control waveform is located at the leftmost or rightmost part of the pulse width control segment of the phase control waveform.

[0028] Optionally, when the level of the sampling segment of a phase control waveform is low first and then high, the high level in the pulse width control segment of the phase control waveform is located at the leftmost side of the pulse width control segment of the phase control waveform;

[0029] When the level of the sampling segment of a phase control waveform is high first and then low, the high level in the pulse width control segment of the phase control waveform is located at the rightmost side of the pulse width control segment of the phase control waveform.

[0030] Optionally, the step of completing the first current sampling in the first sampling period includes:

[0031] In the control cycle T-t2-S min The first current sampling is performed at time t, where T is the control cycle duration, t2 is the second sampling period duration, and S min The shortest time to complete sampling;

[0032] The step of completing the second current sampling in the second sampling period includes:

[0033] During the control cycle TS min Perform the second current sampling at any time.

[0034] Optionally, the first sampling segment and the second sampling segment are equal in duration and are both the sampling window duration.

[0035] Optionally, when the three-phase PWM waveform mode is selected as mode 1, in the control cycle (T - T2) / 2-S min The first current sampling is done at the time (T - T1) / 2-S of the control cycle min The second current sampling is performed at the moment, where T is the control cycle length, S min The minimum time to complete sampling.

[0036] Optionally, the step of obtaining the total high level duration of each phase control waveform in the current control cycle includes:

[0037] Calculate the target voltage of each phase in the current control cycle according to the three-phase current value, the actual motor speed and the target motor speed obtained in the previous control cycle;

[0038] The total high level duration of each phase control waveform is determined according to the bus voltage, the control cycle duration and the target voltage of each phase.

[0039] In a second aspect, an embodiment of the present application provides a computer-readable storage medium, in which a computer program or instructions are stored. When the computer program or instructions are executed by a computer, the motor control method of the first aspect is implemented.

[0040] In a third aspect, an embodiment of the present application provides an air conditioner, comprising a compressor and a controller, wherein the controller is used to control the compressor by the motor control method of the first aspect.

[0041] Compared with the prior art, this application has the following beneficial effects:

[0042] (1) When the symmetrical waveform of the PWM signal does not meet the time required for current sampling, a PWM signal with a sampling segment is generated. The sampling segment has two different non-zero vectors for sampling. The PWM waveform does not require phase shifting and the algorithm is simple.

[0043] (2) When the symmetrical waveform PWM signal meets the time required for current sampling, a symmetrical waveform PWM signal is directly generated to further simplify the algorithm;

[0044] (3) The sampling stage follows the pulse width control stage and can timely and accurately sample the current of the current control cycle, providing a more reliable calculation basis for the next control cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0046] Figure 1 It is a schematic diagram of a three-phase PWM control signal with a symmetrical waveform;

[0047] Figure 2 It is a schematic diagram of a three-phase PWM control signal with an asymmetric waveform;

[0048] Figure 3 A schematic diagram of a circuit system of an air conditioner provided in an embodiment of the present application;

[0049] Figure 4 A schematic diagram of a sampling segment at the end of a control cycle provided by an embodiment of the present application;

[0050] Figure 5 A schematic diagram of a non-zero vector combination of the first sampling segment provided in an embodiment of the present application;

[0051] Figure 6 A schematic diagram of a non-zero vector combination of the second sampling segment provided in an embodiment of the present application;

[0052] Figure 7 A schematic diagram of a non-zero vector combination of the third sampling segment provided in an embodiment of the present application;

[0053] Figure 8 A schematic diagram of a non-zero vector combination of the fourth sampling segment provided in an embodiment of the present application;

[0054] Fig. 9 A schematic diagram of a non-zero vector combination of the fifth sampling segment provided in an embodiment of the present application;

[0055] Fig.10 A schematic diagram of a non-zero vector combination of the sixth sampling segment provided in an embodiment of the present application;

[0056] Fig.11 A schematic diagram of a high level provided in an embodiment of the present application being set to be located in the middle of a pulse width control segment;

[0057] Fig.12 A schematic diagram of a high level provided in an embodiment of the present application being set to be located at the leftmost side of a pulse width control segment;

[0058] Fig.13 A waveform diagram of a control cycle with up to 4 level changes provided in an embodiment of the present application;

[0059] Fig.14 A schematic diagram of a sampling segment in which all levels are low provided in an embodiment of the present application;

[0060] Fig.15 A schematic diagram of a sampling segment in which all levels are high provided in an embodiment of the present application;

[0061] Fig.16 A schematic diagram of a sampling segment provided in an embodiment of the present application in which the level is first low and then high;

[0062] Fig.17 A schematic diagram of a sampling segment provided in an embodiment of the present application in which the level is high first and then low;

[0063] Fig.18 A schematic diagram of a multi-cycle waveform under the first vector combination provided in an embodiment of the present application;

[0064] Fig.19 A schematic diagram of a multi-cycle waveform under the second vector combination provided in an embodiment of the present application;

[0065] Fig. 20 A schematic diagram of a multi-cycle waveform under the third vector combination provided in an embodiment of the present application;

[0066] Fig.21 A schematic diagram of a multi-cycle waveform under the fourth vector combination provided in an embodiment of the present application;

[0067] Fig. 22 A schematic diagram of a multi-cycle waveform under the fifth vector combination provided in an embodiment of the present application;

[0068] Fig.23 A schematic diagram of a multi-cycle waveform under the sixth vector combination provided in an embodiment of the present application. DETAILED DESCRIPTION

[0069] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. The described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described in the drawings here can be arranged and designed in various different configurations.

[0070] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.

[0071] In the description of this application, it should be noted that relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. The term "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium.

[0072] The circuit system of the air conditioner includes a frequency conversion circuit and a motor control circuit, such as Figure 3 The frequency conversion circuit includes a rectifier bridge, a PFC circuit, and a bus capacitor. Cdc , three-phase full-bridge inverter circuit; the motor control circuit includes a sampling resistor R, an amplifier & filter circuit, and a controller.

[0073] The PWM signal sent by the controller controls the PWM drive circuit, and the PWM drive circuit drives the switches in the three-phase full-bridge inverter circuit, thereby driving the compressor.

[0074] In the feedback loop, the sampling resistor R is connected in series with the DC bus ground wire. The current flowing through the sampling resistor R generates a voltage with a small amplitude and interference. After amplification and filtering, a voltage with a larger amplitude and smoother is obtained. It is connected to the AD port of the controller, and the controller performs AD conversion on the voltage to calculate the current.

[0075] The controller is used to execute a motor control method, and the motor control method includes:

[0076] Obtain the total high level duration of each phase control waveform in the current control cycle;

[0077] Select the waveform mode of the three-phase PWM according to the difference between the total high-level durations of the three-phase control waveforms and a preset sampling window duration;

[0078] Generate a three-phase PWM signal according to the waveform mode of the three-phase PWM;

[0079] Control the motor according to the three-phase PWM signal and sample the three-phase current of the motor; the three-phase current is used to determine the total high-level duration of each phase control waveform in the next control cycle. The target voltage of each phase in the current control cycle can be calculated based on the three-phase current values, the actual speed of the motor, and the target speed of the motor obtained in the previous control cycle, and then the total high-level duration of each phase control waveform in the next control cycle can be determined according to the bus voltage, the control cycle duration, and the target voltage of each phase.

[0080] The waveform modes of the three-phase PWM include Mode 1 and Mode 2: The waveform of Mode 1 is a symmetric waveform, such as Figure 1 , and the waveform of Mode 2 is an asymmetric waveform.

[0081] The waveform mode of the three-phase PWM can be selected according to the following method:

[0082] Such as Figure 1 , if the total high-level durations of the three-phase control waveforms in the current control cycle are arranged from long to short as T3>T2>T1, calculate the first duration t2 and the second duration t3 according to the formulas t2=(T3-T2) / 2 and t3=(T2-T1) / 2; compare t2 and t3 with Tmin, and it is divided into the following two situations:

[0083] When t2≥Tmin and t3≥Tmin, select the waveform mode of the three-phase PWM as Mode 1;

[0084] When t2<Tmin or t3<Tmin, select the waveform mode of the three-phase PWM as Mode 2.

[0085] The waveform of Mode 2 is such as Figure 4 , in a control cycle T, there is a pulse width control section 10 and a sampling section 20, and the pulse width control section 10 is before the sampling section 20. The sampling section 20 includes a first sampling section and a second sampling section. The first sampling section is the Figure 4 level corresponding to t1 in, and the second sampling section is the Figure 4 level corresponding to t2 in. Assuming that the sampling window duration is Tmin, t1≥Tmin and t2≥Tmin, then the current can be sampled once at t1 and once at t2.

[0086] t1 and t2 can satisfy t1≥Tmin and t2≥Tmin, and the size relationship between t1 and t2 can be any of the following: t1>t2, t1<t2 or t1=t2. If t1=t2=Tmin is set, the duration of the pulse width control segment can be maximized, thereby shortening the duration of the entire control cycle.

[0087] like Figure 4 , the first vector sampled at t1 is 001, and the second vector sampled at t2 is 011. The first vector and the second vector are different and are non-zero vectors, so the three-phase current can be finally obtained.

[0088] When the PWM waveform is the waveform of mode 2, refer to Figure 4 , can be controlled in the T-t2-S cycle min The first current sampling is performed at time t, where T is the control cycle duration, t2 is the second sampling period duration, and S min The shortest time to complete sampling; it can be in the control cycle TS min The second current sampling is performed at time t2, where t2 is the duration of the second sampling segment.

[0089] When the PWM waveform is the waveform of mode 1, refer to Figure 1 , can be controlled in the period (T - T2) / 2-S min The first current sampling can be done at the control period (T - T1) / 2-S min The second current sampling is performed at the moment, where T is the control cycle length, S min The minimum time to complete sampling.

[0090] When the first vector and the second vector are fixed, changing the duration of the high level in the pulse width control segment 10 of one phase can change the duration of the high level in the entire cycle, thereby changing the voltage of this phase in the motor. The duration of the high level in the pulse width control segment of each phase control waveform is the total duration of the high level of the phase control waveform minus the duration of the high level of the sampling segment of the phase control waveform.

[0091] The principle of changing the voltage by controlling the duration of the high level in the cycle is as follows: suppose the duration of a control cycle is T, T1, T2, and T3 are the pulse width durations of the three phases U, V, and W respectively, and assuming that the bus voltage of the controller is Udc, then in this control cycle, the voltages of the three phases U, V, and W are Udc*(T1 / T), Udc*(T2 / T), and Udc*(T3 / T) respectively, that is, by continuously changing the sizes of T1, T2, and T3 in each control cycle, the three-phase voltage of the motor can be controlled.

[0092] There are 30 combinations of the first vector and the second vector. Any of the 30 combinations can be used as the combination of the first vector and the second vector. Specifically, there are 6 non-zero vectors: 001, 010, 011, 100, 101, and 110. Since the second non-zero vector is different from the first, there are 6×5=30 valid sampling combinations. Figures 5 to 10 , Figure 5 Corresponding to 6 combinations (i.e. ABC corresponds to UVW, UWV, VUW, VWU, WUV or WVU), Figure 6 Corresponding to 6 combinations, Figure 7 Corresponding to 3 combinations (i.e. ABC corresponds to UVW, VWU or WUV), Figure 8 Corresponding to 6 combinations, Fig. 9 Corresponding to 6 combinations, Fig.10 Corresponding to 3 combinations.

[0093] In the pulse width control section, the high level can be set to be at the rightmost position of the pulse width control section. Fig.10 , or it can be set to be in the middle Fig.11 , or it can be set to be on the far left. Fig.12 .

[0094] like Fig.13 For the W phase in the sampling segment, if the level of the sampling segment is low first and then high, and the high level can be set to be located at the rightmost of the pulse width control segment, the W phase has up to 4 level changes in one control cycle. The number of level changes in one control cycle can be minimized by setting as follows:

[0095] like Fig.14 If the levels of the sampling segments of a phase control waveform are all low, the high level in the pulse width control segment of the phase control waveform is located at the leftmost or rightmost side of the pulse width control segment of the phase control waveform. When implemented, it can be set to one of the sides;

[0096] like Fig.15 If the levels of the sampling segments of a phase control waveform are all high, the high level in the pulse width control segment of the phase control waveform is located at the leftmost or rightmost side of the pulse width control segment of the phase control waveform. When implemented, it can be set to one of the sides;

[0097] like Fig.16 , if the level of the sampling segment of a phase control waveform is low first and then high, the high level in the pulse width control segment of the phase control waveform is located at the leftmost side of the pulse width control segment of the phase control waveform;

[0098] like Fig.17 If the level of the sampling segment of a phase control waveform is high first and then low, the high level in the pulse width control segment of the phase control waveform is located at the rightmost side of the pulse width control segment of the phase control waveform.

[0099] By reducing the number of level changes in one control cycle, the switching loss of the device is reduced.

[0100] The above 30 combinations of the first vector and the second vector are combined with the position setting of the high level in the pulse width control section, such as Figures 18 to 23 ,in Fig.18 Corresponding to 6 combinations (i.e. ABC corresponds to UVW, UWV, VUW, VWU, WUV or WVU), Fig.19 Corresponding to 6 combinations, Fig. 20 Corresponding to 3 combinations (i.e. ABC corresponds to UVW, VWU or WUV), Fig.21 Corresponding to 6 combinations, Fig. 22 Corresponding to 6 combinations, Fig.23 Corresponding to 3 combinations.

[0101] The motor three-phase control pulse generation method of the present application can achieve the following beneficial effects:

[0102] Combining the symmetrical and asymmetrical waveform modes, the current can be sampled directly in any control cycle without phase shifting.

[0103] When an asymmetric waveform is used, the sampling segment is composed of two different non-zero vectors and remains unchanged. In this way, the current sampled in each cycle is fixed to a certain two-phase current, and there is no need to determine which phase the sampled current is each time a sample is taken.

[0104] The sampling stage is after the pulse width control stage, and can timely and accurately sample the current of the current control cycle, providing a more reliable calculation basis for the next control cycle;

[0105] It is also possible to set each phase level to change only twice in each PWM control cycle. The smaller the switching loss of the device, the lower the temperature. The sampling period 0, t1, and t2 must correspond to a phase level change, and after determining to use one of the 30 non-zero vectors, it is possible to determine which level changes at which moment. Therefore, in actual operation, only the other 3 level change moments need to be determined. Only 3 level change moments need to be updated in each control cycle, that is, only 1 level change moment is updated per phase in each PWM cycle, while conventional single resistor sampling needs to update 6 level change moments.

[0106] The high level in the above implementation can be replaced by a low level, that is, the motor three-phase control pulse generation method includes:

[0107] Obtain the total low level duration of each phase control waveform in the current control cycle;

[0108] According to the difference between the total durations of the low levels of the three-phase control waveforms and the preset sampling window duration, a waveform mode of the three-phase PWM is selected, and a three-phase PWM signal is generated according to the waveform mode of the three-phase PWM;

[0109] The motor is controlled according to the three-phase PWM signal, and the three-phase current of the motor is sampled; the three-phase current is used to determine the total low-level duration of each phase control waveform in the next control cycle; for the waveform of method 2, the low-level duration in the pulse width control segment of each phase control waveform is the total low-level duration of the phase control waveform minus the low-level duration of the sampling segment of the phase control waveform.

[0110] Based on the above embodiments, an embodiment of the present invention further provides a computer-readable storage medium, in which a computer program or instruction is stored. When the computer program or instruction is executed by a computer, the above-mentioned motor three-phase control pulse generation method is implemented.

[0111] Based on the above embodiments, the embodiments of the present application further provide an air conditioner, which includes a compressor and a controller, and the controller is used to control the compressor through the above-mentioned motor three-phase control pulse generation method.

[0112] The above-described device and system embodiments are merely illustrative, and some or all of the modules may be selected according to actual needs to achieve the purpose of the present embodiment. A person skilled in the art may understand and implement the present embodiment without creative effort.

[0113] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A motor control method, characterized in that: include: Obtain the total high level duration of each phase control waveform in the current control cycle; According to the difference between the total durations of the high levels of the three-phase control waveforms and the preset sampling window duration, a waveform mode of the three-phase PWM is selected, and a three-phase PWM signal is generated according to the waveform mode of the three-phase PWM; The motor is controlled according to the three-phase PWM signal, and the three-phase current of the motor is sampled; the three-phase current is used to determine the total duration of the high level of each phase control waveform in the next control cycle; The three-phase PWM waveform mode includes mode 1 and mode 2; The waveform of the first mode satisfies: the high level of each phase control waveform is located in the middle of the control cycle, and the PWM signal waveform is symmetrical in the control cycle; The waveform of the second mode satisfies: each control cycle of each phase control waveform includes a pulse width control section and a sampling section, the pulse width control section is before the sampling section, the sampling section of each phase control waveform includes a first sampling section and a second sampling section, the duration of the first sampling section and the second sampling section are both greater than or equal to the sampling window duration, the first sampling sections of the three-phase control waveforms are combined into a first vector, the second sampling sections of the three-phase control waveforms are combined into a second vector, the first vector and the second vector are non-zero vectors, the first vector and the second vector are different, and the high level duration in the pulse width control section of each phase control waveform is the total high level duration of the phase control waveform minus the high level duration of the sampling section of the phase control waveform; In the process of controlling the motor by the three-phase PWM signal generated by the second method, the step of sampling the three-phase current of the motor includes: completing a first current sampling in the time period of the first sampling section, and completing a second current sampling in the time period of the second sampling section; Obtaining the three-phase current of the motor according to the first current sampling and the second current sampling; When the level of the sampling segment of a phase control waveform is low first and then high, the high level in the pulse width control segment of the phase control waveform is located at the leftmost side of the pulse width control segment of the phase control waveform; When the level of the sampling segment of a phase control waveform is high first and then low, the high level in the pulse width control segment of the phase control waveform is located at the rightmost side of the pulse width control segment of the phase control waveform.

2. The motor control method according to claim 1, characterized in that: According to the difference between the total durations of the high levels of the three-phase control waveforms and the preset sampling window duration, the step of selecting the waveform mode of the three-phase PWM includes: The total high-level duration of the three-phase control waveform in the current control cycle is arranged from long to short as T3>T2>T1. According to the formula t2=(T3-T2) / 2, t3=(T2-T1) / 2, the first duration t2 and the second duration t3 are calculated; When the first time length is greater than or equal to the sampling window time length, and the second time length is greater than or equal to the sampling window time length, the waveform mode of the three-phase PWM is selected as mode 1; When the first time length is shorter than the sampling window time length, or the second time length is shorter than the sampling window time length, the waveform mode of the three-phase PWM is selected as mode 2.

3. The motor control method according to claim 1, characterized in that: When the sampling segments of a phase control waveform are all low level, the high level in the pulse width control segment of the phase control waveform is located at the leftmost or rightmost of the pulse width control segment of the phase control waveform; When the sampling segments of a phase control waveform are all high level, the high level in the pulse width control segment of the phase control waveform is located at the leftmost or rightmost part of the pulse width control segment of the phase control waveform.

4. The motor control method according to claim 1, characterized in that: The sampling section is located at the rightmost side of the control cycle, and the steps of completing the first current sampling during the first sampling section include: In the control cycle T-t2-S min The first current sampling is performed at time t, where T is the control cycle duration, t2 is the second sampling period duration, and S min The shortest time to complete sampling; The step of completing the second current sampling in the second sampling period includes: During the control cycle TS min Perform the second current sampling at any time.

5. The motor control method according to claim 1, characterized in that: The duration of the first sampling segment is equal to the duration of the second sampling segment, and both are the duration of the sampling window.

6. The motor control method according to claim 1, wherein: When the three-phase PWM waveform mode is selected as mode 1, in the control cycle (T - T2) / 2-S min The first current sampling is done at the time (T - T1) / 2-S of the control cycle min The second current sampling is performed at the moment, where T is the control cycle length, S min The minimum time to complete sampling.

7. The motor control method according to claim 1, characterized in that: The steps of obtaining the total high level duration of each phase control waveform in the current control cycle include: Calculate the target voltage of each phase in the current control cycle according to the three-phase current value, the actual motor speed and the target motor speed obtained in the previous control cycle; The total high level duration of each phase control waveform is determined according to the bus voltage, the control cycle duration and the target voltage of each phase.

8. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program or instruction. When the computer program or instruction is executed by a computer, the motor control method according to any one of claims 1 to 7 is implemented.

9. An air conditioner, characterized in that: The air conditioner includes a compressor and a controller, and the controller is used to control the compressor by the motor control method according to any one of claims 1 to 7.

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