Single-resistance sampling method, device, medium, system, motor and electrical equipment

Abstract

The application discloses a single-resistance sampling method, device, medium, system, motor and electrical equipment, and belongs to the field of motor control. In the application, the target switching time is switched with the initial switching time, and the duty cycle of the switch as a whole is unchanged, so that the synthesized reference voltage vector is unchanged. After the initial switching time is changed into the target switching time, the first conduction time of the switch of the second phase is different from the first conduction time of the switch of the first phase by a preset time, and the first conduction time of the switch of the third phase is different from the first conduction time of the switch of the second phase by the preset time. Since the preset time is greater than or equal to the minimum sampling time, and the preset time length is less than the minimum sampling time, the sampling point is arranged at the first conduction of the switch for the preset time length, so that the sampling point is ensured to be in the effective vector interval. At this time, since the switch that is turned on has been turned on for a certain time, and the state of other switches has not been switched, the current is stable when sampling, and the sampling current error is small.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of motor control, in particular, to a single-resistance sampling method, device, medium, system, motor and electrical appliance. BACKGROUND

[0002] Permanent magnet synchronous motor is widely used in daily household appliances, electric vehicles, and the current mainstream permanent magnet synchronous motor control method is field oriented control (FOC). This control method needs real-time rotor position and current size feedback to implement control, and also needs to solve the rotor position of the motor through current, so the current sampling during the operation of the motor in the motor control system using sensorless control such as household air conditioner is particularly important, and high-precision current can greatly enhance the control accuracy of the motor. As the core part of motor vector control, in the traditional sampling control method, multiple current sensors or multiple current sampling resistors are usually connected in series in the inverter module bridge arm for sampling. Although the sampling effect is good and the sampling precision is high, the cost of multiple current sensors is high for products sensitive to the price of components. To reduce the cost, a single-resistance time-sharing sampling phase current reconstruction method can be considered, that is, the current is sampled from the DC bus combined with the switching state of the inverter module. This scheme can obtain complete motor phase current by measuring the voltage on the sampling resistor and converting and processing, and then reconstructing the phase current.

[0003] Compared with the traditional multi-current sensor sampling method, single-resistance sampling saves cost, but also has a series of technical difficulties. The most critical point is that single-resistance sampling must ensure a minimum sampling time. The current value sampled less than the minimum sampling time may be distorted, and the ideal current information cannot be obtained. The traditional five-segment and seven-segment SVPWM modulation method will have an unobservable area at low, medium and high modulation ratio stages, which may appear in the current oscillation stage sampling, resulting in large current sampling error, or it may cause sampling in the zero vector stage and cannot solve the third phase current through Kirchhoff's current law, so that the motor control cannot be realized. SUMMARY

[0004] In order to overcome the shortcomings of the prior art, the present application provides a single-resistance sampling method, device, medium, system, motor and electrical appliance, to solve the problem that the control method of the existing SVPWM will have an unobservable area at low, medium and high modulation ratio stages, so that the current sampling reconstruction will have a reconstruction dead zone, which may appear in the current oscillation stage sampling, resulting in large current sampling error, or it may cause sampling in the zero vector stage and cannot solve the third phase current through Kirchhoff's current law, so that the motor control cannot be realized.

[0005] The technical solution adopted by this application to solve its technical problems is:

[0006] In a first aspect, a single resistor sampling method is provided, comprising:

[0007] Obtaining respectively the initial switching times of the three-phase switches of the three-phase PWM wave obtained based on seven-segment SVPMW modulation, wherein the initial switching times are used to control the time of each state switching of the switch of the corresponding phase within one cycle, and the initial switching times include a first initial switching time of the switch of the first phase, a second initial switching time of the switch of the second phase, and a third initial switching time of the switch of the third phase;

[0008] The target switching time of the three-phase switch of the three-phase PWM wave is determined based on the initial switching information based on the minimum sampling time, wherein the first target switching time of the first-phase switch is the first initial switching time, the second target switching time of the second-phase switch is the second initial switching time minus the first difference, and the third target switching time of the third-phase switch is the third-phase initial switching time minus the second difference, wherein the first difference = the first conduction time of the switch within the second initial switching time - the first conduction time of the switch within the first initial switching time + the preset time; the second difference = the first conduction time of the switch within the third initial switching time - the first conduction time of the switch within the second target switching time + the preset time, and the preset time is greater than or equal to the minimum sampling time;

[0009] The corresponding switches are controlled respectively according to the target switching time, and sampling is performed after each phase switch is first turned on for a preset time, where the preset time is less than the minimum sampling time.

[0010] Furthermore, it also includes:

[0011] The preset time is the minimum sampling time.

[0012] Furthermore, it also includes:

[0013] When in a high modulation ratio area or a low modulation ratio area, the preset time is the minimum sampling time;

[0014] When in the normal reconstruction area, the preset time is greater than the minimum sampling time.

[0015] Furthermore, it also includes:

[0016] determining a duty cycle of the three-phase switch based on the initial switching time;

[0017] The phase with the largest duty cycle is used as the first phase, the phase with the smallest duty cycle is used as the third phase, and the remaining phase is used as the second phase.

[0018] Further, the preset time length is half of the minimum sampling time.

[0019] In a second aspect, a single-resistor sampling device is provided, comprising:

[0020] an initial switching time acquisition module configured to acquire initial switching times of switches of three phases of a three-phase PWM wave based on seven-segment SVPMW modulation, the initial switching times being used to control time of each state switching of the switches of the corresponding phases in a cycle, the initial switching times comprising a first initial switching time of a switch of a first phase, a second initial switching time of a switch of a second phase, and a third initial switching time of a switch of a third phase;

[0021] a target switching time determination module configured to determine target switching times of the switches of the three phases of the three-phase PWM wave based on the minimum sampling time and the initial switching times, the first target switching time of the switch of the first phase being the first initial switching time, the second target switching time of the switch of the second phase being the second initial switching time minus a first difference value, and the third target switching time of the switch of the third phase being the third initial switching time minus a second difference value, wherein the first difference value = a first turn-on time of the switch in the second initial switching time - a first turn-on time of the switch in the first initial switching time + a preset time, the second difference value = a first turn-on time of the switch in the third initial switching time - a first turn-on time of the switch in the second target switching time + the preset time, and the preset time is greater than or equal to the minimum sampling time;

[0022] a switch control and sampling module configured to control the switches of the corresponding phases according to the target switching times and to perform sampling after a preset time length in which the switches of each phase are turned on for the first time, the preset time length being less than the minimum sampling time.

[0023] In a third aspect, a computer-readable storage medium is provided, which stores a computer program, the computer program being executable by a processor to implement the single-resistor sampling method provided in the above embodiments.

[0024] In a fourth aspect, a single-resistor sampling system is provided, comprising:

[0025] at least one processor and at least one memory;

[0026] the memory storing executable instructions of the processor;

[0027] the processor being configured to execute the single-resistor sampling method described above.

[0028] In a fifth aspect, a motor is provided, which applies the single-resistor sampling method described above.

[0029] In a sixth aspect, an electrical appliance is provided, which comprises the motor described above.

[0030] Advantages:

[0031] The technical scheme of the application provides a single-resistance sampling method, device, medium, system, motor and electrical equipment. Initial switching times of three-phase switches of three-phase PWM waves obtained based on seven-segment SVPMW modulation are acquired respectively, and then target switching times of the three-phase switches of the three-phase PWM waves are determined based on minimum sampling time from the initial switching information. Finally, the corresponding switches are controlled according to the target switching times, and sampling is performed after a preset time length of the first conduction of each-phase switch. In the application, the target switching times and the initial switching times are different in switching time, but the interval of any two adjacent switching times is unchanged, that is, the duty cycle of the switches as a whole is unchanged, so that the synthesized reference voltage vector is unchanged. After the initial switching times become the target switching times, the first conduction time of the switch of the second phase and the first conduction time of the switch of the first phase are different by a preset time, and the first conduction time of the switch of the third phase and the first conduction time of the switch of the second phase are different by a preset time. Since the preset time is greater than or equal to the minimum sampling time, and the preset time length is less than the minimum sampling time, the sampling point is set at the preset time length of the first conduction of the switch, so as to ensure that the sampling point is in the effective vector interval. At this time, since the switch that is turned on has been turned on for a certain time, and the state of the other switch has not been switched, the current is stable when sampling, and the sampling current error is small. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical scheme in the embodiments of the application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative effort.

[0033] Figure 1 It is a motor control flowchart provided by the embodiments of the application;

[0034] Figure 2 It is a single-resistance sampling principle diagram provided by the embodiments of the application;

[0035] Figure 3 It is a single-resistance current minimum sampling time composition schematic diagram provided by the embodiments of the application;

[0036] Figure 4 It is a single-resistance sampling time schematic diagram provided by the embodiments of the application;

[0037] Figure 5 It is a current reconstruction area schematic diagram provided by the embodiments of the application;

[0038] Figure 6is a switch state schematic diagram of an existing non-observation area provided by an embodiment of the present application;

[0039] Figure 7 is a single-resistance sampling method flowchart provided by an embodiment of the present application;

[0040] Figure 8 is a sampling Figure 7 switch state schematic diagram after the method shown in the figure;

[0041] Figure 9 is a PWM phase shift and sampling trigger simulation schematic diagram provided by an embodiment of the present application;

[0042] Figure 10 is a bus current and bus sampling current schematic diagram provided by an embodiment of the present application;

[0043] Figure 11 is a current sensor sampling current and single-resistance sampling reconstructed current comparison schematic diagram provided by an embodiment of the present application;

[0044] Figure 12 is a current sensor sampling current local detail and single-resistance sampling reconstructed current local detail comparison schematic diagram provided by an embodiment of the present application;

[0045] Figure 13 is a single-resistance sampling device structure schematic diagram provided by an embodiment of the present application. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme of the present application will be described in detail below in combination with the drawings and embodiments. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of the present application.

[0047] The motor control flowchart using seven-segment SVPWM modulation is shown in Figure 1 The current sampling resistance is connected in series in the DC bus to sample the phase current of the motor. The principle of single-resistance sampling is shown in Figure 2 In an ideal current sampling situation, current sampling only needs an instant, but in the actual situation, there is a dead time T dead of the control system, a device conduction time T on , a current sampling analog-digital conversion processing time T trans and a current smooth time T stable , so there is a minimum sampling T min of current sampling, and the distribution of each period is shown in Figure 3As shown, the minimum sampling time is composed of:

[0048] T min = T dead + T on + T stable + T trans (1.1)

[0049] When the sampling time is less than the effective vector acting time, the current sampling may occur in the current oscillation stage, resulting in a large current sampling error, or the third phase current cannot be solved through the Kirchhoff current law, so that the motor control cannot be realized.

[0050] As Figure 4 shown, in the traditional seven-segment SVPWM modulation scheme, the switching state is symmetrically distributed, and sampling is performed in the effective sampling vector interval. Because of the existence of the minimum current sampling time, the effective vector will be less than 2 in the high and low modulation ratio and sector boundary area, so that the current sampling reconstruction will have a reconstruction dead zone, as Figure 5 shown. Therefore, no matter which sector the motor is in, as long as sector switching and high and low modulation ratio occur, there will be an unobservable reconstruction area, Figure 6 the switching state of which is a non-observable area.

[0051] To solve this problem, with reference to Figure 7 , the embodiment of the present application provides a single-resistance sampling method, comprising:

[0052] S11: acquiring initial switching times of three-phase switches of three-phase PWM waves obtained based on seven-segment SVPMW modulation, respectively, the initial switching times being used for controlling the time of each state switching of the corresponding phase switch in a period, the initial switching times including a first initial switching time of a switch of a first phase, a second initial switching time of a switch of a second phase, and a third initial switching time of a switch of a third phase;

[0053] Wherein, the determination of the first phase, the second phase and the third phase is based on the duty ratio, specifically, the duty ratio of the three-phase switch is determined based on the initial switching time; the phase with the largest duty ratio is taken as the first phase, the phase with the smallest duty ratio is taken as the third phase, and the remaining phase is taken as the second phase.

[0054] For example, according to the vector synthesis principle, there is the following relationship between the reference voltage vector and the basic voltage vector:

[0055]

[0056] Wherein, T (xxx) represents the action time of the basic voltage vector xxx, T sare the zero vectors, and U1-U6 are the basic voltage vectors. According to the synthesis principle, the relationships between U1, U2 and U4 and the other five vectors are as follows:

[0057] U6 = U2 + U4

[0058] U3 = U1 + U2

[0059] U5 = U1 + U4

[0060] U7 = U1 + U2 + U4 (1.3)

[0061] Then the relationship between the reference voltage vector and the basic vectors can be rewritten as:

[0062]

[0063] Then

[0064]

[0065] Obviously, after the equivalent replacement, the reference voltage can be synthesized by the three basic voltage vectors U1, U2 and U4; similarly, the reference voltage vector can also be represented by the three basic voltage vectors U3, U5 and U6. The action time of each basic voltage vector is composed of the time of the four switch states, and the four parts represent the total on time of the upper bridge of each phase. Taking U1 as an example, (T (100) +T (101) +T (110) +T (111) ) represents the total on time of the A-phase upper bridge. Let

[0066] T a = T (001) +T (011) +T (101) +T (111)

[0067] T b = T (010) +T (011) +T (110) +T (111)

[0068] T c = T (100) +T (101) +T (110) +T (111) (1.6)

[0069] Substitute the basic voltage vector times T a , T b , T c into the reference voltage vector synthesis formula (1.5), and the following equation can be obtained

[0070]

[0071] Because the amplitude and phase of U1, U2, U4 are independent of the modulation mode, the size of the resultant vector is only related to the on-time, so it is only necessary to ensure that the on-time of the three-phase bridge arm is consistent with the duty cycle of the original SVPWM modulation to ensure that the generated reference voltage vector remains unchanged. To realize real-time modulation of the SVPWM signal, it is necessary to know the reference voltage vector U ref is located, and then the reference voltage vector is synthesized by using the adjacent basic voltage vectors and zero vectors in the sector. Here, sector 1 is still taken as an example for analysis, and the action time of the basic voltage vectors and zero vectors required for synthesizing an arbitrary reference voltage vector in the sector is calculated:

[0072]

[0073] T0 = T s -T4-T6(1.8)

[0074] In the formula, U dc is the DC bus voltage, u α , u β are the components of the reference voltage vector U ref in the α, β axes, T4, T6 are the action time lengths of U4 and U6 respectively, and T0 is the action time length of the zero vector U0 (U7).

[0075] Therefore, it is easy to know that the vector switching time of sector 1 is as follows:

[0076] T x = (T s -T4-T6) / 4 = T0 / 4

[0077] T y =T x +T4 / 6 = T0 / 4 + T4 / 6

[0078] T z =T y +T6 / 2 = T0 / 4 + T4 / 6 + T6 / 2(1.9)

[0079] In the above formula, Tx, Ty, Tz are the wave generation times of the three PWM waves after phase shifting. That is, the first conduction time in the initial switching time.

[0080] S12: determining target switching time of three-phase switch of three-phase PWM wave based on minimum sampling time and initial switching information, first target switching time of switch of the first phase is the first initial switching time, second target switching time of switch of the second phase is the second initial switching time minus first difference value, third target switching time of switch of the third phase is the third initial switching time minus second difference value, wherein the first difference value = switch first conduction time in the second initial switching time - switch first conduction time in the first initial switching time + preset time; the second difference value = switch first conduction time in the third initial switching time - switch first conduction time in the second target switching time + preset time, the preset time is greater than or equal to the minimum sampling time.

[0081] In one embodiment, the preset time is the minimum sampling time. For example, as shown in Figure 8 , the switch conduction time node of the phase with the largest duty ratio is unchanged, the sampling point is set in the first half cycle, and the switch conduction time of the other two phases is adjusted according to the sampling requirement, and the adjusted switch conduction time of the other two phases in the first half cycle is:

[0082] T x = T0 / 4

[0083] T y = T x + T min = T0 / 4 + T min

[0084] T z = T y + T min = T0 / 4 + 2T min (1.10)

[0085] The phase shift mode is as shown in Figure 8 , accordingly, the second half cycle also needs to be right shifted by a corresponding time. Before modification, the timing of seven-segment SVPWM modulation is:

[0086] t = [T0 / 4 T4 / 2 T6 / 2 T0 / 2 T6 / 2 T4 / 2 T0 / 4] (1.11)

[0087] After modification, the modulation signal changes from seven-segment to three-segment, and the new switch timing of each phase is as follows:

[0088] t1 = [T0 / 4 T s -T0 / 2 T0 / 4]

[0089] t2 = [T0 / 4 + T min T6 + T0 / 2 T s -3T0 / 4 - T min ]

[0090] t3 = [T0 / 4 + 2T min T0 / 2T s -3T0 / 4-2T min ](1.12)

[0091] and the timing is no longer strictly symmetrical, but this method has the advantage that there is no need to compare the effective vector T4 / 2, T6 / 2 action time length with T min , directly modify the phase-shifted SVPWM modulation signal to ensure that sufficient current sampling time is given, without additional calculation time and calculation resources.

[0092] In the above embodiment, the preset time is the minimum sampling time, so that accurate sampling can be ensured in any case. However, if multiple sampling is required, the preset time can be greater than the minimum sampling time. However, in the case where the preset time is greater than the minimum sampling time in the high modulation ratio and low modulation ratio regions, the final collected current is also inaccurate.

[0093] Therefore, in another embodiment, when in the high modulation ratio region or the low modulation ratio region, the preset time is the minimum sampling time; when in the normal reconstruction region, the preset time is greater than the minimum sampling time.

[0094] Wherein, the high modulation ratio region and the low modulation ratio region and the normal reconstruction region refer to the annotations of Figure 5 .

[0095] S13: According to the target switching time, control the corresponding switch respectively, and sample after each phase switch is turned on for a preset time, which is less than the minimum sampling time. That is, the sampling point in the above embodiment is in the first half cycle.

[0096] As a preferred implementation manner of the embodiment of the present application, the preset time is half of the minimum sampling time. It should be noted that the sampling point is when each phase switch is turned on for a preset time, and the phase switch has been turned on for a period of time, and the other phase switches do not need to be switched, so the current is in a stable period at this time, and since the phase switch is turned on for the first time, it is in the effective vector stage, not the zero vector, so the sampling current can be accurately determined at this time.

[0097] Figure 9 The simulation diagram of the phase-shifted sampling is shown in the figure. The minimum sampling effective vector time is set to 6μs. The sampling trigger fully considers the dead time + current oscillation time of 3μs. The sampling trigger time is in the middle part of the effective sampling vector, which ensures that stable current information can be sampled. Figure 10 The sampling current obtained by sampling the bus is compared with the bus current, Figure 10The upper half is the bus current, and the lower half is the bus sampling current. The sampled current is then reconstructed. Figure 11 The comparison between the three-phase current sampled by the current sensor and the current reconstructed by single resistor sampling is shown in the figure. Figure 11 The upper part is the three-phase current sampled by the current sensor, and the lower part is the current reconstructed after single resistor sampling. The third-phase current is solved by Kirchhoff's current law using the two-phase current sampled:

[0098] i a +i b +i c =0(1.13)

[0099] Figure 12 It can be clearly seen that compared with the sampling and reconstruction current ( Figure 12 The upper part shows the local details of the current sampled by the current sensor, and the lower part shows the local details of the current reconstructed by sampling with a single resistor). The current sampled by the current sensor has high-frequency ripple, which exists regardless of whether it is symmetrical PWM modulation or asymmetrical PWM modulation. However, the error range of the ripple is still within the controllable range. The method proposed in the embodiment of the present application combined with the current reconstruction method greatly reduces the ripple, which shows that this method is extremely superior.

[0100] The single-resistor sampling method provided in the embodiment of the present application obtains the initial switching time of the three-phase switch of the three-phase PWM wave obtained based on the seven-segment SVPMW modulation, and then determines the target switching time of the three-phase switch of the three-phase PWM wave based on the initial switching information based on the minimum sampling time; finally, the corresponding switches are controlled according to the target switching time, and sampling is performed after each phase switch is first turned on for a preset time. In this application, the target switching time is different from the initial switching time, but the time interval between any two adjacent switching times remains unchanged, that is, the overall duty cycle of the switch remains unchanged, so the synthesized reference voltage vector remains unchanged. After the initial switching time changes to the target switching time, the first turn-on time of the second phase switch differs from the first turn-on time of the first phase switch by a preset time, and the first turn-on time of the third phase switch differs from the first turn-on time of the second phase switch by a preset time. Since the preset time is greater than or equal to the minimum sampling time, and the preset duration is less than the minimum sampling time, the sampling point is set at the preset duration of the first turn-on of the switch to ensure that the sampling point is in the valid vector interval. At this time, since the turned-on switch has been turned on for one end of the time and the other switch states have not yet switched, the current is stable during sampling and the sampling current error is small. It ensures that single-resistance sampling has sufficient sampling time regardless of low, medium or high modulation ratios, and the code amount is small, the calculation is simple, the sampling current is accurate, and the reconstructed current has less high-frequency ripple than the multi-sensor sampling current.

[0101] Based on the same inventive concept,Figure 13 As shown, the application also provides a single-resistance sampling device 130, comprising:

[0102] An initial switching time acquisition module 131 is configured to acquire initial switching times of three-phase switches of a three-phase PWM wave based on seven-segment SVPMW modulation, the initial switching times being used to control time of each state switching of the corresponding phase switch in a period, and the initial switching times comprising a first initial switching time of a first-phase switch, a second initial switching time of a second-phase switch, and a third initial switching time of a third-phase switch.

[0103] The duty cycles of the three-phase switches are determined based on the initial switching times; the phase with the largest duty cycle is taken as the first phase, the phase with the smallest duty cycle is taken as the third phase, and the remaining phase is taken as the second phase.

[0104] A target switching time determination module 132 is configured to determine target switching times of the three-phase switches of the three-phase PWM wave based on the minimum sampling time and the initial switching information, the first target switching time of the first-phase switch being the first initial switching time, the second target switching time of the second-phase switch being the second initial switching time minus a first difference value, and the third target switching time of the third-phase switch being the third initial switching time minus a second difference value, wherein the first difference value = a first conduction time of the switch in the second initial switching time - a first conduction time of the switch in the first initial switching time + a preset time, the second difference value = a first conduction time of the switch in the third initial switching time - a first conduction time of the switch in the second target switching time + the preset time, and the preset time is greater than or equal to the minimum sampling time.

[0105] In one embodiment, the preset time is the minimum sampling time.

[0106] In another embodiment, when in a high modulation ratio region or a low modulation ratio region, the preset time is the minimum sampling time.

[0107] When in a normal reconstruction region, the preset time is greater than the minimum sampling time.

[0108] A switch control and sampling module 133 is configured to control the corresponding switches according to the target switching times and to perform sampling after a preset time length of the first conduction of the switch in each phase, and the preset time length is less than the minimum sampling time.

[0109] As a preferred implementation manner of the embodiment, the preset time length is half of the minimum sampling time.

[0110] The single-resistance sampling device provided by the embodiments of the present application respectively acquires initial switching times of three-phase switches of three-phase PWM waves obtained based on seven-segment SVPMW modulation, then determines target switching times of the three-phase switches of the three-phase PWM waves based on the initial switching information and a minimum sampling time, and finally controls the corresponding switches according to the target switching times and samples after a preset time length of the first conduction of each-phase switch.

[0111] Based on the same inventive concept, the present application further provides a computer readable storage medium storing a computer program, which can implement the single-resistance sampling method provided by the above embodiments when executed by a processor.

[0112] The computer readable storage medium provided by the embodiments of the present application can respectively acquire initial switching times of three-phase switches of three-phase PWM waves obtained based on seven-segment SVPMW modulation, then determine target switching times of the three-phase switches of the three-phase PWM waves based on the initial switching information and a minimum sampling time, and finally control the corresponding switches according to the target switching times and sample after a preset time length of the first conduction of each-phase switch.

[0113] Based on the same inventive concept, the present application further provides a single-resistance sampling system, comprising:

[0114] at least one processor and at least one memory;

[0115] the memory stores executable instructions of the processor;

[0116] the processor is configured to execute the single-resistor sampling method provided by the above-mentioned embodiments.

[0117] The single-resistor sampling system provided by the embodiments of the present application stores executable instructions of the processor in the memory. When the executable instructions are executed, the processor can acquire initial switching times of three-phase switches based on three-phase PWM waves obtained by seven-segment SVPMW modulation, and then determine target switching times of the three-phase switches of the three-phase PWM waves based on the initial switching information and the minimum sampling time. Finally, the corresponding switches are controlled according to the target switching times, and sampling is performed after a preset time length of the first conduction of each-phase switch. In the present application, the target switching time is different from the initial switching time, but the interval of switching times of any two adjacent times is unchanged, that is, the duty cycle of the switch as a whole is unchanged, so the synthesized reference voltage vector is unchanged. After the initial switching time is changed to the target switching time, the first conduction time of the switch of the second phase is different from the first conduction time of the switch of the first phase by a preset time, and the first conduction time of the switch of the third phase is different from the first conduction time of the switch of the second phase by a preset time. Since the preset time is greater than or equal to the minimum sampling time, and the preset time length is less than the minimum sampling time, the sampling point is set at the preset time length of the first conduction of the switch, so that the sampling point is in the effective vector interval. At this time, since the switch that is turned on has been turned on for a certain time, and the state of the other switch has not been switched, the current is stable when sampling, and the sampling current error is small.

[0118] Based on the same inventive concept, the present application also provides an electric machine applying the single-resistor sampling method provided by the above-mentioned embodiments.

[0119] The motor provided in the embodiments of the present application can obtain initial switching time of three-phase switches of three-phase PWM waves based on seven-segment SVPMW modulation by applying the single-resistance sampling method provided in the above embodiments, and then determine target switching time of the three-phase switches of the three-phase PWM waves based on the minimum sampling time from the initial switching information; finally, the corresponding switches are controlled according to the target switching time, and sampling is performed after a preset time length of the first conduction of each-phase switch. In the present application, the target switching time is different from the initial switching time, but the interval of switching time of any two adjacent times is unchanged, that is, the duty cycle of the switches as a whole is unchanged, so the synthesized reference voltage vector is unchanged. After the initial switching time is changed to the target switching time, the first conduction time of the switch of the second phase is different from the first conduction time of the switch of the first phase by a preset time, and the first conduction time of the switch of the third phase is different from the first conduction time of the switch of the second phase by a preset time. Since the preset time is greater than or equal to the minimum sampling time, and the preset time length is less than the minimum sampling time, the sampling point is set at the preset time length of the first conduction of the switch, so as to ensure that the sampling point is in the effective vector interval. At this time, since the switch that is turned on has been turned on for a certain time, and the state of other switches has not been switched, the current is stable when sampling, and the sampling current error is small

[0120] Based on the same inventive concept, the present application further provides an electrical appliance device comprising the motor provided in the above embodiments.

[0121] It should be noted that in the description of the present application, the terms "first", "second" and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance. In addition, in the description of the present application, unless otherwise specified, the meaning of "a plurality of" is at least two.

[0122] It can be understood that the same or similar parts in the above embodiments can be mutually referred to, and the contents not described in detail in some embodiments can be referred to the same or similar contents in other embodiments.

Claims

1. A single resistor sampling method, characterized in that: include: Obtaining respectively the initial switching times of the three-phase switches of the three-phase PWM wave obtained based on seven-segment SVPMW modulation, wherein the initial switching times are used to control the time of each state switching of the switch of the corresponding phase within one cycle, and the initial switching times include a first initial switching time of the switch of the first phase, a second initial switching time of the switch of the second phase, and a third initial switching time of the switch of the third phase; The target switching time of the three-phase switch of the three-phase PWM wave is determined based on the initial switching time based on the minimum sampling time, wherein the first target switching time of the first-phase switch is the first initial switching time, the second target switching time of the second-phase switch is the second initial switching time minus the first difference, and the third target switching time of the third-phase switch is the third initial switching time minus the second difference, wherein the first difference = the first conduction time of the switch within the second initial switching time - the first conduction time of the switch within the first initial switching time + the preset time; the second difference = the first conduction time of the switch within the third initial switching time - the first conduction time of the switch within the second target switching time + the preset time, and the preset time is greater than or equal to the minimum sampling time; The corresponding switches are controlled respectively according to the target switching time, and sampling is performed after each phase switch is first turned on for a preset time, where the preset time is less than the minimum sampling time.

2. The method according to claim 1, characterized in that Also includes: When in a high modulation ratio area or a low modulation ratio area, the preset time is the minimum sampling time; When in the normal reconstruction area, the preset time is greater than the minimum sampling time.

3. The method according to claim 1, characterized in that Also includes: determining a duty cycle of the three-phase switch based on the initial switching time; The phase with the largest duty cycle is used as the first phase, the phase with the smallest duty cycle is used as the third phase, and the remaining phase is used as the second phase.

4. The method according to claim 1, wherein: The preset duration is half of the minimum sampling time.

5. A single resistor sampling device, characterized in that: include: An initial switching time acquisition module is used to respectively acquire the initial switching time of the three-phase switches of the three-phase PWM wave obtained based on the seven-segment SVPMW modulation. The initial switching time is used to control the time of each state switching of the switch of the corresponding phase within one cycle. The initial switching time includes a first initial switching time of the switch of the first phase, a second initial switching time of the switch of the second phase, and a third initial switching time of the switch of the third phase; a target switching time determination module, configured to determine, based on the minimum sampling time and the initial switching time, the target switching time of the three-phase switch of the three-phase PWM wave, wherein the first target switching time of the first-phase switch is the first initial switching time, the second target switching time of the second-phase switch is the second initial switching time minus the first difference, and the third target switching time of the third-phase switch is the third initial switching time minus the second difference, wherein the first difference = the first conduction time of the switch within the second initial switching time - the first conduction time of the switch within the first initial switching time + a preset time; the second difference = the first conduction time of the switch within the third initial switching time - the first conduction time of the switch within the second target switching time + a preset time, and the preset time is greater than or equal to the minimum sampling time; The switch control and sampling module is used to control the corresponding switches according to the target switching time and perform sampling after each phase switch is first turned on for a preset time, where the preset time is less than the minimum sampling time.

6. A computer-readable storage medium, characterized in that: A computer program is stored thereon, and when the computer program is executed by a processor, the method according to any one of claims 1 to 4 can be implemented.

7. A single resistor sampling system, characterized in that: include: at least one processor and at least one memory; The memory stores executable instructions of the processor; The processor is configured to execute the method according to any one of claims 1 to 4.

8. A motor, characterized in that: The method according to any one of claims 1 to 4 is used.

9. An electrical device, characterized in that: Including the motor according to claim 8.

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