A motor three-phase control pulse generation method, storage medium and air conditioner

Abstract

The embodiment of the present application provides a method for generating a three-phase control pulse of a motor, a storage medium and an air conditioner, and relates 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 part is generated, and the sampling part has two different non-zero vectors for sampling. The PWM waveform does not require phase shifting, and the algorithm is simple. Moreover, when a symmetrical waveform PWM signal meets the time required for current sampling, a symmetrical waveform PWM signal is directly generated, further simplifying the algorithm.

Description

Technical Field

[0001] The present application relates to the technical field of permanent magnet synchronous motor control, and in particular to a method for generating three-phase control pulses of a motor, a storage medium and an air conditioner. Background Art

[0002] In the control algorithm of permanent magnet synchronous motor (PMSM), current sampling is an important link. The three-phase current of the motor is obtained through the sampling circuit and sampling algorithm, and then the motor is controlled through related calculation and feedback links.

[0003] Currently, there are two commonly used current sampling methods: dual-resistance sampling and single-resistance sampling. Among them, single-resistance sampling is increasingly used in various controllers due to its simple circuit and low cost.

[0004] According to the existing algorithm, when using single resistor sampling, it is necessary to sample twice in one control cycle, and the two times must be different non-zero vectors (000 and 111 are zero vectors, and other combinations are non-zero vectors). In this way, two phase currents in the three phases can be obtained, and 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. 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.

[0005] 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.

[0006] For example Figure 1 When sampling is selected between t2 and t3, if t3<Tmin, the accurate current cannot be sampled within t3. For this problem, the common method is to perform phase shifting, that is, shifting the V phase pulse width to the left when generating the PWM signal, and if necessary, shifting the W phase to the left.

[0007] like Figure 2After phase shifting, t2≥Tmin and t3≥Tmin. The phase shifting operation can solve the problem of current sampling, but different control cycles may require phase shifting, while others may not. Some may only need to move one phase, while others 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.

[0008] Therefore, how to generate appropriate PWM pulses so that the real and accurate current can be sampled without phase shifting the PWM waveform is a technical problem that needs to be solved. Summary of the invention

[0009] The purpose of the present application is to provide a method for generating three-phase control pulses of a motor, a storage medium and an air conditioner to generate appropriate PWM pulses, so that real and accurate current can be sampled without phase shifting of the PWM waveform.

[0010] To achieve the above objectives, the embodiments of the present application adopt the following technical solutions.

[0011] In a first aspect, an embodiment of the present application provides a method for generating a three-phase control pulse of a motor, comprising:

[0012] Get the total high level duration of each phase control waveform in the current PWM cycle. The total high level duration of the three-phase control waveform is arranged from long to short as T3>T2>T1;

[0013] According to the formula t2=(T3-T2) / 2, t3=(T2-T1) / 2, calculate the first duration parameter t2 and the second duration parameter t3;

[0014] When the first duration parameter and the second duration parameter both meet the duration required for current sampling, the generated three-phase PWM signal meets the following waveform: the high level is located in the middle of the PWM cycle, and the PWM signal waveform is symmetrical in the PWM cycle;

[0015] When the first duration parameter or the second duration parameter does not meet the duration required for current sampling, the generated three-phase PWM signal meets the following waveform: in one PWM cycle, each phase control waveform includes a sampling part and a pulse width control part, the sampling part is before the pulse width control part, the sampling part of each phase control waveform includes a first sampling level and a second sampling level, the duration of the first sampling level and the second sampling level both meet the duration required for current sampling, the first sampling levels of the three-phase control waveforms are combined into a first vector, the second sampling levels 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 part of each phase control waveform is the total high level duration of the phase control waveform minus the high level duration of the sampling part of the phase control waveform.

[0016] Optionally, the high level in the pulse width control portion of each phase control waveform is located at the leftmost or rightmost portion of the pulse width control portion of the phase control waveform.

[0017] Optionally, in each PWM cycle, the level of any phase control waveform changes at most twice.

[0018] Optionally, if the levels of the sampling part of a certain phase control waveform are all low, the high level in the pulse width control part of the phase control waveform is located at the leftmost or rightmost part of the pulse width control part of the phase control waveform;

[0019] If the levels of the sampling part of a certain phase control waveform are all high, the high level in the pulse width control part of the phase control waveform is located at the leftmost or rightmost part of the pulse width control part of the phase control waveform.

[0020] Optionally, if the level of the sampling part of a phase control waveform is low first and then high, the high level in the pulse width control part of the phase control waveform is located at the leftmost of the pulse width control part of the phase control waveform;

[0021] If the level of the sampling part of a phase control waveform is high first and then low, the high level in the pulse width control part of the phase control waveform is located at the rightmost side of the pulse width control part of the phase control waveform.

[0022] Optionally, the step of obtaining the total duration of the high level of each phase control waveform includes:

[0023] Calculate the target voltage of each phase in the current PWM cycle according to the three-phase current values, the actual motor speed and the target motor speed obtained in the previous PWM cycle;

[0024] The total high level duration of each phase control waveform is determined according to the bus voltage, the PWM cycle duration and the target voltage of each phase.

[0025] Optionally, the duration of the first sampling level and the second sampling level are both sampling window durations.

[0026] Optionally, the high level mentioned above can be replaced by a low level, that is, the motor three-phase control pulse generation method includes:

[0027] Get the total low-level duration of each phase control waveform in the current PWM cycle. The total low-level duration of the three-phase control waveforms is arranged from long to short as T3>T2>T1;

[0028] According to the formula t2=(T3-T2) / 2, t3=(T2-T1) / 2, calculate the first duration parameter t2 and the second duration parameter t3;

[0029] When the first duration parameter and the second duration parameter both meet the duration required for current sampling, the generated three-phase PWM signal meets the following waveform: the low level is located in the middle of the PWM cycle, and the PWM signal waveform is symmetrical in the PWM cycle;

[0030] When the first duration parameter or the second duration parameter does not meet the duration required for current sampling, the generated three-phase PWM signal meets the following waveform: in one PWM cycle, each phase control waveform includes a sampling part and a pulse width control part, the sampling part is before the pulse width control part, the sampling part of each phase control waveform includes a first sampling level and a second sampling level, the duration of the first sampling level and the second sampling level both meet the duration required for current sampling, the first sampling levels of the three-phase control waveforms are combined into a first vector, the second sampling levels 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 low level duration in the pulse width control part of each phase control waveform is the total low level duration of the phase control waveform minus the low level duration of the sampling part of the phase control waveform.

[0031] In a second aspect, an embodiment of the present application 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 motor three-phase control pulse generation method of the first aspect is implemented.

[0032] 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 generate a three-phase control waveform through the motor three-phase control pulse generation method of the first aspect, and drive the compressor to operate according to the three-phase control waveform.

[0033] Compared with the prior art, this application has the following beneficial effects:

[0034] The motor three-phase control pulse generation method provided in the embodiment of the present application generates a PWM signal with a sampling part when the symmetrical waveform PWM signal does not meet the time required for current sampling, and the sampling part has two different non-zero vectors for sampling, and the PWM waveform does not need phase shifting, and the algorithm is simple. Moreover, when the symmetrical waveform PWM signal meets the time required for current sampling, the symmetrical waveform PWM signal is directly generated, which further simplifies the algorithm. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] 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.

[0036] Figure 1 It is a schematic diagram of a three-phase PWM control signal with a symmetrical waveform;

[0037] Figure 2 It is a schematic diagram of the phase-shifted PWM waveform;

[0038] Figure 3 A schematic diagram of a three-phase PWM control signal with an asymmetric waveform provided in an embodiment of the present application;

[0039] Figure 4 A schematic diagram of a non-zero vector combination of the first sampling part provided in an embodiment of the present application;

[0040] Figure 5 A schematic diagram of a non-zero vector combination of the second sampling part provided in an embodiment of the present application;

[0041] Figure 6 A schematic diagram of a non-zero vector combination of the third sampling part provided in an embodiment of the present application;

[0042] Figure 7 A schematic diagram of a non-zero vector combination of the fourth sampling part provided in an embodiment of the present application;

[0043] Figure 8 A schematic diagram of a non-zero vector combination of the fifth sampling part provided in an embodiment of the present application;

[0044] Fig. 9 A schematic diagram of a non-zero vector combination of the sixth sampling part provided in an embodiment of the present application;

[0045] Fig.10 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 portion;

[0046] Fig.11 A schematic diagram of a high level provided in an embodiment of the present application being set to be located at the far right of a pulse width control portion;

[0047] Fig.12 A schematic diagram of a sampling part with all low levels provided in an embodiment of the present application;

[0048] Fig.13 A schematic diagram of a sampling part with all levels being high provided in an embodiment of the present application;

[0049] Fig.14 A schematic diagram of a sampling part provided in an embodiment of the present application where the level is first low and then high;

[0050] Fig.15 A schematic diagram of a sampling part provided in an embodiment of the present application in which the level is high first and then low;

[0051] Fig.16 A schematic diagram of a circuit system of an air conditioner provided in an embodiment of the present application. DETAILED DESCRIPTION

[0052] 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.

[0053] 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.

[0054] 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.

[0055] The present application provides a method for generating three-phase control pulses for a motor, including:

[0056] Get the total high level duration of each phase control waveform in the current PWM cycle. The total high level duration of the three-phase control waveform is arranged from long to short as T3>T2>T1;

[0057] like Figure 1 , according to the formula t2=(T3-T2) / 2, t3=(T2-T1) / 2, calculate the first duration parameter t2 and the second duration parameter t3;

[0058] After obtaining the first duration parameter t2 and the second duration parameter t3, the following two situations can be considered:

[0059] (1) When the first time parameter t2 and the second time parameter t3 both meet the time required for current sampling, the generated three-phase PWM signal satisfies the following waveform: the high level is located in the middle of the PWM cycle, and the PWM signal waveform is symmetrical in the PWM cycle, such as Figure 1 , the rising edge times of the three phases are (T - T3) / 2, (T - T2) / 2, (T - T1) / 2, and the falling edge times are (T + T3) / 2, (T + T2) / 2, (T + T1) / 2;

[0060] (2) When the first time parameter t2 or the second time parameter t3 does not meet the time required for current sampling, the generated three-phase PWM signal satisfies the following waveform:

[0061] like Figure 3 , in one PWM cycle, each phase control waveform includes a sampling part 10 and a pulse width control part 20, and the sampling part 10 is before the pulse width control part 20;

[0062] The sampling portion 10 of each phase control waveform includes a first sampling level and a second sampling level. The first sampling level is Figure 3 The level corresponding to t1 in the figure, the second sampling level is Figure 3 The level corresponding to t2, t1 and t2 both meet the time required for current sampling, so the current can be sampled once at t1 and once at t2;

[0063] The first sampling level combination of the three-phase control waveform is a first vector, and the second sampling level combination of the three-phase control waveform is a second vector. The first vector and the second vector are non-zero vectors, and the first vector and the second vector are different. Figure 3 , the first vector is 001, the second vector is 011;

[0064] The high level duration in the pulse width control part 20 of each phase control waveform is the total high level duration of the phase control waveform minus the high level duration of the sampling part 10 of the phase control waveform.

[0065] The PWM signal is generated by the above-mentioned motor three-phase control pulse generation method, and the three-phase voltage of the motor is controlled by the PWM signal, which combines two waveform modes: symmetrical waveform and asymmetrical waveform: when the symmetrical waveform PWM signal does not meet the time required for current sampling, an asymmetrical waveform PWM signal is generated, which has a sampling part PWM signal, and the sampling part has two different non-zero vectors for sampling, and the PWM waveform does not need phase shifting, and the algorithm is simple. When the symmetrical waveform PWM signal meets the time required for current sampling, a symmetrical waveform PWM signal is directly generated, which further simplifies the algorithm.

[0066] The total high level duration of each phase control waveform in the current PWM cycle can be obtained by the following method: according to the three-phase current value obtained in the previous PWM cycle, the actual motor speed and the motor target speed, the target voltage of each phase of the current PWM cycle is calculated, and then according to the bus voltage, the PWM cycle duration and the target voltage of each phase, the total high level duration of the current PWM cycle of each phase control waveform is determined. The principle of PWM signal controlling the three-phase voltage of the motor is as follows:

[0067] Assume that the duration of a PWM cycle is T, T1, T2, and T3 are the pulse width durations of the three phases U, V, and W respectively. Assuming that the bus voltage of the controller is Udc, then in this PWM 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 PWM cycle, the three-phase voltage of the motor can be controlled.

[0068] Therefore, first obtain the voltage required for each phase of the motor. The voltage required for the three phases is U1, U2, and U3. Then, according to the bus voltage Udc, PWM cycle duration T, U1, U2, and U3, the total high-level duration T1, T2, and T3 of each phase control waveform has the following relationship with the voltage: U1=Udc*(T1 / T), U2=Udc*(T2 / T), and U3=Udc*(T3 / T). The calculation formula T1=T*(U1 / Udc), T2=T*(U2 / Udc), and T3=T*(U3 / Udc) can be obtained. Through this calculation formula, the total high-level duration T1, T2, and T3 of the three-phase control waveform can be calculated.

[0069] After obtaining the total duration of the high level of the three-phase control waveform, the first duration parameter t2 and the second duration parameter t3 are calculated according to the formula t2=(T3-T2) / 2, t3=(T2-T1) / 2. According to the first duration parameter t2 and the second duration parameter t3, it can be judged whether it is suitable to generate a symmetrical waveform PWM signal. Specifically, the duration required for current sampling is the sampling window duration Tmin. Comparing t2 and t3 with Tmin, it is divided into the following two cases:

[0070] When t2 ≥ Tmin and t3 ≥ Tmin, that is Figure 1 in Figure 1 , t2 ≥ Tmin and t3 ≥ Tmin, then the current can be sampled once at t2 in Figure 1 and once at t3, and the two samplings are different non - zero vectors, and finally the three - phase current can be obtained; Figure 1 in Figure 1 , the current can be sampled once at t2 and once at t3, and the two samplings are different non - zero vectors, and finally the three - phase current can be obtained;

[0071] When t2 < Tmin or t3 < Tmin, for example Figure 1 in Figure 1 , t3 < Tmin, then when sampling the current at t3 in Figure 1 , an accurate current cannot be obtained, and a new method is needed to generate a PWM signal with an asymmetric waveform. Figure 1 in Figure 1 , when sampling the current at t3, an accurate current cannot be obtained, and a new method is needed to generate a PWM signal with an asymmetric waveform.

[0072] The PWM signal with an asymmetric waveform is as shown in Figure 3 . If the sampling part 10 of one phase is all low, for example, the U - phase, then the high - level duration D1 of the pulse - width control part 20 of this phase is D1 = T1; if the sampling part 10 of one phase is all high, for example, the W - phase, then the high - level duration D1 of the pulse - width control part 20 of this phase is D1 = T1 - t1 - t2; if in the sampling part 10 of one phase, t1 is low and t2 is high, for example, the V - phase, then the high - level duration D1 of the pulse - width control part 20 of this phase is D1 = T1 - t2; if in the sampling part 10 of one phase, t1 is high and t2 is low, then the high - level duration D1 of the pulse - width control part 20 of this phase is D1 = T1 - t1. Figure 3 The PWM signal with an asymmetric waveform is as shown in Figure 3 . If the sampling part 10 of one phase is all low, for example, the U - phase, then the high - level duration D1 of the pulse - width control part 20 of this phase is D1 = T1; if the sampling part 10 of one phase is all high, for example, the W - phase, then the high - level duration D1 of the pulse - width control part 20 of this phase is D1 = T1 - t1 - t2; if in the sampling part 10 of one phase, t1 is low and t2 is high, for example, the V - phase, then the high - level duration D1 of the pulse - width control part 20 of this phase is D1 = T1 - t2; if in the sampling part 10 of one phase, t1 is high and t2 is low, then the high - level duration D1 of the pulse - width control part 20 of this phase is D1 = T1 - t1.

[0073] The magnitude relationship between the duration t1 of the first sampling level and the duration t2 of the second sampling level only needs to meet the duration required for current sampling, and any of the following methods can be used: t1 > t2, t1 < t2, or t1 = t2. If t1 = t2 = Tmin is set, the maximum duration can be left for the pulse - width control part 20, thereby shortening the duration of the entire PWM cycle.

[0074] The sampling part consists of two different non - zero vectors. There are 6 non - zero vectors: 001, 010, 011, 100, 101, 110. Since the second non - zero vector is different from the first one, there are a total of 30 valid sampling combinations, as shown in Figures 4 to 9 . Figures 4 to 9 Figure 4 corresponds to 6 combinations (i.e., ABC corresponds to UVW, UWV, VUW, VWU, WUV, or WVU), Figure 5 corresponds to 6 combinations, Figure 6 corresponds to 3 combinations (i.e., ABC corresponds to UVW, VWU, WUV), Figure 7 corresponds to 6 combinations, Figure 8 corresponds to 6 combinations, Fig. 9 corresponds to 3 combinations. During implementation, it can be set as one of the 30 kinds.

[0075] In the pulse width control part 20, the high level can be set to be located at the leftmost part of the pulse width control part such as Fig. 9 , or it can be set to be in the middle Fig.10 , or it can be set to be on the far right. Fig.11 .

[0076] The position of the high level in the pulse width control section 20 can be set in combination with the settings of the first sampling level and the second sampling level:

[0077] like Fig.12 If the level of the sampling part of a phase control waveform is all low, the high level in the pulse width control part of the phase control waveform is located at the leftmost or rightmost side of the pulse width control part of the phase control waveform. When implemented, it can be set to one of the sides;

[0078] like Fig.13 If the levels of the sampling part of a phase control waveform are all high, the high level in the pulse width control part of the phase control waveform is located at the leftmost or rightmost side of the pulse width control part of the phase control waveform. When implemented, it can be set to one of the sides;

[0079] like Fig.14 , if the level of the sampling part of a phase control waveform is low first and then high, the high level in the pulse width control part of the phase control waveform is located at the leftmost of the pulse width control part of the phase control waveform;

[0080] like Fig.15 If the level of the sampling part of a phase control waveform is high first and then low, the high level in the pulse width control part of the phase control waveform is located at the rightmost side of the pulse width control part of the phase control waveform.

[0081] The above setting can make the level of any phase control waveform change at most twice in one PWM cycle, thereby minimizing the number of level changes. The fewer the number of level changes in one PWM cycle, the smaller the switching loss of the device and the lower the temperature.

[0082] 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:

[0083] Get the total low-level duration of each phase control waveform in the current PWM cycle. The total low-level duration of the three-phase control waveforms is arranged from long to short as T3>T2>T1;

[0084] According to the formula t2=(T3-T2) / 2, t3=(T2-T1) / 2, calculate the first duration parameter t2 and the second duration parameter t3;

[0085] When the first duration parameter and the second duration parameter both meet the duration required for current sampling, the generated three-phase PWM signal meets the following waveform: the low level is located in the middle of the PWM cycle, and the PWM signal waveform is symmetrical in the PWM cycle;

[0086] When the first duration parameter or the second duration parameter does not meet the duration required for current sampling, the generated three-phase PWM signal meets the following waveform: in one PWM cycle, each phase control waveform includes a sampling part and a pulse width control part, the sampling part is before the pulse width control part, the sampling part of each phase control waveform includes a first sampling level and a second sampling level, the durations of the first sampling level and the second sampling level both meet the duration required for current sampling, the first sampling levels of the three-phase control waveforms are combined into a first vector, the second sampling levels 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 low level duration in the pulse width control part of each phase control waveform is the total low level duration of the phase control waveform minus the low level duration of the sampling part of the phase control waveform.

[0087] Based on the above embodiments, the embodiments of the present application also provide an air conditioner, which includes a compressor and a controller. The controller is used to generate a three-phase control waveform through the above-mentioned motor three-phase control pulse generation method, and drive the compressor to operate according to the three-phase control waveform.

[0088] like Fig.16 The circuit system of the air conditioner includes a rectifier bridge, a PFC circuit, and a bus capacitor. Cdc The frequency conversion circuit is composed of a three-phase full-bridge inverter circuit, a sampling resistor R, an amplifier & filter circuit, and a control chip to form a motor control circuit. The control chip is the above-mentioned controller. The three-phase full-bridge inverter circuit drives the compressor, and the three-phase full-bridge inverter circuit is driven by a PWM drive circuit. The PWM drive circuit receives the PWM signal sent by the control chip.

[0089] 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 large amplitude and a smoother voltage is obtained, which is connected to the AD port of the control chip. The control chip performs AD conversion on the voltage and calculates the current. The control chip executes the above-mentioned motor three-phase control pulse generation method when generating a PWM signal.

[0090] 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.

[0091] The motor three-phase control pulse generation method of the present application combines symmetrical and asymmetrical waveform modes. No matter in which PWM cycle, the current can be sampled directly without phase shifting.

[0092] When an asymmetric waveform is used, the sampling part 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 sampling is performed.

[0093] It is also possible to set each phase level to change only twice in each PWM cycle, and the smaller the switching loss of the device, the lower the temperature. The sampling part must correspond to a phase level change at time 0, time t1, and time t2, and after determining to use one of the 30 non-zero vectors, it is possible to determine which level changes at which time. 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 PWM cycle, and conventional single-resistance sampling needs to update 6 level change moments.

[0094] 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.

[0095] 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 method for generating three-phase control pulses of a motor, characterized in that: include: Get the total high level duration of each phase control waveform in the current PWM cycle. The total high level duration of the three-phase control waveform is arranged from long to short as T3>T2>T1; According to the formula t2=(T3-T2) / 2, t3=(T2-T1) / 2, calculate the first duration parameter t2 and the second duration parameter t3; When the first duration parameter and the second duration parameter both meet the duration required for current sampling, the generated three-phase PWM signal meets the following waveform: the high level is located in the middle of the PWM cycle, and the PWM signal waveform is symmetrical in the PWM cycle; When the first duration parameter or the second duration parameter does not satisfy the duration required for current sampling, the generated three-phase PWM signal satisfies the following waveform: in one PWM cycle, each phase control waveform includes a sampling part and a pulse width control part, the sampling part is before the pulse width control part, the sampling part of each phase control waveform includes a first sampling level and a second sampling level, the duration of the first sampling level and the second sampling level both satisfy the duration required for current sampling, the first sampling levels of the three-phase control waveforms are combined into a first vector, the second sampling levels 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 part of each phase control waveform is the total high level duration of the phase control waveform minus the high level duration of the sampling part of the phase control waveform; In each PWM cycle, the level of any phase control waveform changes at most twice; If the level of the sampling part of a phase control waveform is low first and then high, the high level in the pulse width control part of the phase control waveform is located at the leftmost part of the pulse width control part of the phase control waveform; If the level of the sampling part of a phase control waveform is high first and then low, the high level in the pulse width control part of the phase control waveform is located at the rightmost side of the pulse width control part of the phase control waveform.

2. The motor three-phase control pulse generation method according to claim 1, characterized in that: The high level in the pulse width control portion of each phase control waveform is located at the leftmost or rightmost portion of the pulse width control portion of the phase control waveform.

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

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

5. The motor three-phase control pulse generation method according to claim 1, characterized in that: The durations of the first sampling level and the second sampling level are both sampling window durations.

6. A method for generating three-phase control pulses of a motor, characterized in that: include: Get the total low-level duration of each phase control waveform in the current PWM cycle. The total low-level duration of the three-phase control waveforms is arranged from long to short as T3>T2>T1; According to the formula t2=(T3-T2) / 2, t3=(T2-T1) / 2, calculate the first duration parameter t2 and the second duration parameter t3; When the first duration parameter and the second duration parameter both meet the duration required for current sampling, the generated three-phase PWM signal meets the following waveform: the low level is located in the middle of the PWM cycle, and the PWM signal waveform is symmetrical in the PWM cycle; When the first duration parameter or the second duration parameter does not satisfy the duration required for current sampling, the generated three-phase PWM signal satisfies the following waveform: in one PWM cycle, each phase control waveform includes a sampling part and a pulse width control part, the sampling part is before the pulse width control part, the sampling part of each phase control waveform includes a first sampling level and a second sampling level, the duration of the first sampling level and the second sampling level both satisfy the duration required for current sampling, the first sampling levels of the three-phase control waveforms are combined into a first vector, the second sampling levels 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 low level duration in the pulse width control part of each phase control waveform is the total low level duration of the phase control waveform minus the low level duration of the sampling part of the phase control waveform; In each PWM cycle, the level of any phase control waveform changes at most twice; If the level of the sampling part of a phase control waveform is high first and then low, the low level in the pulse width control part of the phase control waveform is located at the leftmost side of the pulse width control part of the phase control waveform; If the level of the sampling part of a phase control waveform is low first and then high, the low level in the pulse width control part of the phase control waveform is located at the rightmost side of the pulse width control part of the phase control waveform.

7. 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 three-phase control pulse generation method according to any one of claims 1 to 6 is implemented.

8. An air conditioner, characterized in that: The air conditioner comprises a compressor and a controller, wherein the controller is used to generate a three-phase control waveform by the motor three-phase control pulse generation method according to any one of claims 1 to 6, and drive the compressor to operate according to the three-phase control waveform.

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