Inverter modulation method and related device

Abstract

The embodiment of the invention relates to the technical field of inverters, and discloses a modulation method of an inverter and a related device, the inverter adopts a space vector pulse width modulation mode, a target voltage vector is obtained in each modulation period, and when the target voltage vector is in an overmodulation second region of the inverter, the overmodulation second region of the inverter is subjected to overmodulation. And calculating a synthetic voltage vector according to the angle value and the modulation degree of the target voltage vector, and controlling the inverter to output the synthetic voltage vector. The voltage vector actually required to be output by the inverter can be determined according to the angle value and the modulation degree of the target voltage vector, voltage fluctuation is suppressed, the continuity of the actual output voltage of the inverter is improved, and the output voltage of the inverter is improved. And the jump degree of the output voltage and the voltage waveform distortion rate are reduced.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of inverters, and in particular to a modulation method of an inverter and related devices. Background Art

[0002] An inverter is a power electronic device that converts direct current (DC) into alternating current (AC). Currently, pulse width modulation (PWM) technology is commonly used to control its output voltage. Under PWM control, the inverter's modulation range can be divided into linear modulation, overmodulation region 1, and overmodulation region 2. Compared to PWM modulation in the linear modulation and overmodulation regions 1, PWM modulation in overmodulation region 2 can increase the inverter's voltage output capability.

[0003] Currently, when the inverter operates in overmodulation zone 2, the modulation index is typically used as the only variable in vector allocation to determine the voltage vector the inverter actually needs to output. The modulation index is the ratio of the reference phase voltage fundamental amplitude to the inverter's maximum output phase voltage fundamental amplitude.

[0004] In the process of implementing this application, the inventors found that there are at least the following problems in the prior art: this method of determining the actual output voltage vector of the inverter only by using the modulation index as a variable will cause the actual output voltage of the inverter to be discontinuous, the voltage jump to be severe, and the voltage waveform distortion to increase. Summary of the Invention

[0005] The embodiments of the present application aim to provide a modulation method and related devices for an inverter, so as to improve the continuity of the actual output voltage of the inverter and reduce the degree of jump of the output voltage and the voltage waveform distortion rate.

[0006] The embodiments of this application provide the following technical solutions:

[0007] In a first aspect, an embodiment of the present application provides a modulation method for an inverter, wherein the inverter adopts a space vector pulse width modulation method. The modulation method for the inverter includes:

[0008] Obtaining the target voltage vector in each modulation cycle;

[0009] When the target voltage vector is in the second overmodulation zone of the inverter, a synthetic voltage vector is calculated according to the angle value of the target voltage vector and the modulation index;

[0010] Control the inverter to output a synthetic voltage vector.

[0011] In some embodiments, before obtaining the target voltage vector in each modulation cycle, the method further includes:

[0012] According to the modulation range of the target voltage vector, the modulation area of ​​the inverter is divided into a linear modulation area, an overmodulation area 1 and an overmodulation area 2;

[0013] The modulation range is the range of the modulation index of the target voltage vector, and the modulation index is the ratio of the amplitude of the target voltage vector to the maximum phase voltage fundamental amplitude output by the inverter.

[0014] The linear modulation area corresponds to the first modulation range, the overmodulation area 1 corresponds to the second modulation range, and the overmodulation area 2 corresponds to the third modulation range. The first modulation range is the modulation index ∈(0, first preset value], the second modulation range is the modulation index ∈(first preset value, second preset value], and the third modulation range is the modulation index ∈(second preset value, 1].

[0015] In some embodiments, a modulation method for an inverter is applied to a controller, the controller includes a first current regulator and a second current regulator, and a target voltage vector is synthesized by a first voltage component and a second voltage component;

[0016] Get the target voltage vector, including:

[0017] Get the d-axis reference current and the q-axis reference current;

[0018] Perform coordinate transformation on the three-phase current output by the inverter to obtain the actual d-axis current and q-axis current in the two-phase rotating coordinate system;

[0019] Calculating a first error signal between a d-axis reference current and a d-axis actual current, and a second error signal between a q-axis reference current and a q-axis actual current;

[0020] Performing proportional control and integral control on the first error signal by a first current regulator to obtain a d-axis reference voltage in a two-phase rotating coordinate system;

[0021] Performing proportional control and integral control on the second error signal by a second current regulator to obtain a q-axis reference voltage in a two-phase rotating coordinate system;

[0022] Coordinate transformation is performed on the d-axis reference voltage and the q-axis reference voltage to obtain a first voltage component and a second voltage component in a two-phase stationary coordinate system.

[0023] In some embodiments, before calculating the synthetic voltage vector according to the angle value of the target voltage vector and the modulation coefficient, the method further includes:

[0024] Calculate the modulation depth based on the target voltage vector;

[0025] When the modulation index is greater than a second preset value, determining that the target voltage vector is in the second overmodulation region;

[0026] The modulation index is calculated using the following formula:

[0027]

[0028] Among them, MI represents the modulation index, u α represents the first voltage component of the target voltage vector in the α-axis direction of the two-phase stationary coordinate system, u β The second voltage component of the target voltage vector in the β-axis direction of the two-phase stationary coordinate system, V dc Indicates the bus voltage value of the inverter.

[0029] In some embodiments, each operating state of the inverter corresponds to a basic space vector, the basic space vector includes a zero vector or a non-zero vector, and the multiple non-zero vectors divide the space voltage vector plane into a plurality of sectors;

[0030] The synthetic voltage vector is calculated based on the angle value of the target voltage vector and the modulation index, including:

[0031] Determine the sector where the target voltage vector is located and divide the sector into two angle intervals;

[0032] Calculating an angle value of a target voltage vector, and determining an angle interval of the target voltage vector according to the angle value, wherein the angle interval is an interval consisting of a first angle and a second angle, and the first angle is smaller than the second angle;

[0033] Calculate a first proportional coefficient according to the modulation index;

[0034] Multiplying the first proportional coefficient by the second angle to obtain a third angle;

[0035] When the angle value of the target voltage vector is greater than or equal to the first angle and the angle value of the target voltage vector is less than the third angle, calculating a synthetic voltage vector according to the first proportional coefficient, the basic space vector, and the target voltage vector;

[0036] When the angle value of the target voltage vector is greater than or equal to the third angle and the angle value of the target voltage vector is less than the second angle, the second proportional coefficient is calculated based on the first proportional coefficient, and the synthetic voltage vector is calculated based on the first proportional coefficient, the second proportional coefficient, the basic space vector, and the target voltage vector.

[0037] In some embodiments, the angle value of the target voltage vector is calculated using the following formula:

[0038]

[0039] Where θ represents the angle value of the target voltage vector, u β The second voltage component of the target voltage vector in the β-axis direction of the two-phase stationary coordinate system, u αrepresents the first voltage component of the target voltage vector in the α-axis direction of the two-phase stationary coordinate system;

[0040] The first proportionality factor is calculated using the following formula:

[0041]

[0042] Wherein, P1 represents the first proportional coefficient, MI represents the modulation index, and a represents the second preset value.

[0043] In some embodiments, the vector endpoints of the plurality of non-zero vectors are sequentially connected to form a regular hexagon;

[0044] Calculating a synthetic voltage vector according to the first proportional coefficient, the basic space vector, and the target voltage vector includes:

[0045] Scaling the target voltage vector to the boundary of the regular hexagon to obtain a first vector, wherein the first vector has the same direction as the target voltage vector;

[0046] Determine the angle between the target voltage vector and each non-zero vector, and use the non-zero vector with the smallest angle as the second vector;

[0047] Calculate the synthetic voltage vector based on the first vector, the second vector and the first proportional coefficient:

[0048] The resultant voltage vector is calculated using the following formula:

[0049] Vreal=(1-P1)*V1+P1*V2

[0050] Wherein, Vreal represents the resultant voltage vector, P1 represents the first proportional coefficient, V1 represents the first vector, and V2 represents the second vector.

[0051] In some embodiments, calculating the second proportionality coefficient based on the first proportionality coefficient includes:

[0052] taking the difference between the second angle and the third angle as the first difference;

[0053] taking the difference between the second angle and the angle value of the target voltage vector as a second difference;

[0054] Calculating a second proportional coefficient based on the first proportional coefficient, the first difference, and the second difference;

[0055] The second proportional coefficient is calculated using the following formula:

[0056]

[0057] Wherein, P2 represents the second proportional coefficient, θ1 represents the first difference, θ2 represents the second difference, and P1 represents the first proportional coefficient.

[0058] In some embodiments, the vector endpoints of the plurality of non-zero vectors are sequentially connected to form a regular hexagon;

[0059] Calculating a synthetic voltage vector according to the first proportional coefficient, the second proportional coefficient, the basic space vector, and the target voltage vector includes:

[0060] Scaling the target voltage vector to the boundary of the regular hexagon to obtain a first vector, wherein the first vector has the same direction as the target voltage vector;

[0061] Determine the angle between the target voltage vector and each non-zero vector, and use the non-zero vector with the smallest angle as the second vector;

[0062] The resultant voltage vector is calculated based on the first vector, the second vector, the first proportional coefficient, and the second proportional coefficient:

[0063] The resultant voltage vector is calculated using the following formula:

[0064] Vreal=(1-P2)*V1+P1*V2

[0065] Wherein, Vreal represents the resultant voltage vector, P2 represents the second proportional coefficient, V1 represents the first vector, P1 represents the first proportional coefficient, and V2 represents the second vector.

[0066] In a second aspect, an embodiment of the present application provides a controller, the controller comprising:

[0067] at least one processor, and

[0068] a memory communicatively coupled to at least one processor, wherein:

[0069] The memory stores instructions that can be executed by at least one processor. The instructions are executed by the at least one processor to enable the at least one processor to perform the modulation method of the inverter according to the first aspect.

[0070] In a third aspect, an embodiment of the present application provides a drive system, the drive system comprising:

[0071] As the controller of the second aspect;

[0072] The inverter is connected to the controller and is used to convert direct current into alternating current according to the control signal sent by the controller.

[0073] In a fourth aspect, an embodiment of the present application provides a refrigerator compressor, comprising:

[0074] Such as the drive system of the third aspect;

[0075] The motor is connected to the drive system and is used to convert alternating current into mechanical energy.

[0076] In a fifth aspect, an embodiment of the present application provides a non-volatile computer-readable storage medium, wherein the non-volatile computer-readable storage medium stores computer-executable instructions, and the computer-executable instructions are used to enable a controller to execute the modulation method of the inverter of the first aspect.

[0077] Beneficial effects of the embodiments of the present application: Different from the prior art, the embodiments of the present application provide a modulation method for an inverter, wherein the inverter adopts a space vector pulse width modulation method, and the modulation method of the inverter includes: obtaining a target voltage vector in each modulation cycle; when the target voltage vector is in the second overmodulation zone of the inverter, calculating a synthetic voltage vector according to the angle value of the target voltage vector and the modulation index; and controlling the inverter to output the synthetic voltage vector.

[0078] By obtaining the target voltage vector in each modulation cycle, when the target voltage vector is in the second overmodulation zone of the inverter, the synthetic voltage vector is calculated according to the angle value and modulation index of the target voltage vector, and the inverter is controlled to output the synthetic voltage vector. The present application can determine the voltage vector that the inverter actually needs to output according to the angle value and modulation index of the target voltage vector, suppress voltage fluctuations, improve the continuity of the actual output voltage of the inverter, and reduce the degree of output voltage jump and the voltage waveform distortion rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0079] One or more embodiments are exemplarily illustrated by corresponding drawings, which do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0080] Figure 1 This is a structural diagram of an inverter provided in an embodiment of the present application;

[0081] Figure 2 is a schematic diagram of a sector provided in an embodiment of the present application;

[0082] Figure 3 This is a flow chart of a method for controlling an inverter provided in an embodiment of the present application;

[0083] Figure 4 1 is a schematic diagram of a controller provided in an embodiment of the present application controlling a motor through a magnetic field oriented control method;

[0084] Figure 5 is a schematic diagram of an angle interval provided in an embodiment of the present application;

[0085] Figure 6This is a structural diagram of a modulation device for an inverter provided in an embodiment of the present application;

[0086] Figure 7 This is a schematic diagram of the structure of a controller provided in an embodiment of the present application;

[0087] Figure 8 This is a schematic structural diagram of a drive system provided in an embodiment of the present application;

[0088] Figure 9 This is a structural diagram of a refrigerator compressor provided in an embodiment of the present application.

[0089] Description of Figure Numbers:

[0090] Label name Label name 10 Inverter 11 First bridge arm 12 Second bridge arm 13 The third bridge arm 20 motor 30 Controller 301 First comparator 302 Speed ​​controller 303 Second comparator 304 Second current regulator 305 First current regulator 306 Park Inverse Converter 307 Space Vector Modulator 308 Field weakening controller 309 The third comparator 310 Park converter 311 Clark converter 312 Motor State Estimator 600 Modulation device of inverter 601 Get Unit 602 Computing Unit 603 Output unit 31 processor 32 Memory 800 Drive system 900 refrigerator compressor DETAILED DESCRIPTION

[0091] In order to facilitate understanding of the present application, the present application is described in more detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that when an element is described as "fixed to" another element, it can be directly on the other element, or there can be one or more centered elements therebetween. When an element is described as "connected to" another element, it can be directly connected to the other element, or there can be one or more centered elements therebetween. The terms "vertical", "horizontal", "left", "right" and similar expressions used in this specification are for illustrative purposes only.

[0092] Unless otherwise defined, all technical and scientific terms used in this specification have the same meanings as those commonly understood by those skilled in the art to which this application belongs. The terms used in this specification and in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" as used in this specification includes any and all combinations of one or more of the relevant listed items.

[0093] The technical solution of this application is described in detail below with reference to the accompanying drawings:

[0094] An inverter is a power electronic device that converts direct current into alternating current. In modern electric drive systems, inverters are commonly used to drive motors. Motors are devices that convert electrical energy into mechanical energy using the principle of electromagnetic induction. To meet increasing operational efficiency requirements, the back-EMF constant of motors is being designed to be higher. For example, the back-EMF constant of the permanent-magnet synchronous motor (PMSM) inside a refrigerator compressor is designed to be higher to improve its efficiency. However, a higher back-EMF constant causes the motor to generate a higher back-EMF well before reaching its rated speed, thus limiting further speed increases.

[0095] Currently, by optimizing the pulse width modulation (PWM) method, the voltage utilization rate of the inverter is improved, so that the inverter can output a higher effective AC voltage, thereby increasing the driving voltage supplied to the motor, increasing the motor speed, reducing the motor operating current, and thus improving the operating efficiency of the refrigerator compressor.

[0096] PWM is a technology that controls output voltage or power by adjusting the duty cycle (i.e., pulse width) of a pulse signal. By controlling the on and off times of the power switching devices in the inverter, the inverter generates a specific voltage waveform, thereby controlling the operation of the motor. Under PWM control, the inverter's operating state is called the modulation region, which includes the linear modulation region and the nonlinear modulation region (also known as the overmodulation region).

[0097] Specifically, PWM modulation technology is used to control the inverter's output voltage to transition from a linear modulation region to a nonlinear modulation region to improve the inverter's voltage utilization. The nonlinear modulation region includes a nonlinear modulation region 1 (i.e., overmodulation region 1) and a nonlinear modulation region 2 (i.e., overmodulation region 2).

[0098] In the linear modulation region, the PWM signal's modulation amplitude remains within the carrier's linear range, resulting in a nearly sinusoidal output voltage waveform and low harmonic content. However, compared to the overmodulation region, voltage utilization is lower. When the motor requires a higher output voltage, linear modulation cannot meet the demand, requiring nonlinear modulation, entering the overmodulation region.

[0099] In the overmodulation region 1, the modulation wave amplitude exceeds the carrier's linear range, resulting in clipping or pulse width saturation, and distorted output voltage waveforms. However, compared to the linear modulation region, voltage utilization is improved, and the amplitude of the fundamental component of the output voltage gradually approaches the theoretical value as the modulation depth increases. The theoretical value is greater than the maximum output voltage in the linear modulation region and less than the theoretical limit of the six-step waveform.

[0100] In the second overmodulation zone, the output voltage waveform tends to be a square wave, the harmonic content increases, and the waveform quality decreases, but the voltage utilization rate reaches the maximum, and the amplitude of the fundamental component of the output voltage gradually reaches the theoretical limit as the modulation depth increases.

[0101] Some PWM modulation methods operate in the linear modulation region and overmodulation region 1. In this case, the inverter's output voltage waveform is continuously adjustable without jumps, but the voltage output capacity has an upper limit, preventing higher voltages. To maintain the required motor speed, deeper field weakening regulation is required for compensation, which fails to optimize the refrigerator compressor's operating efficiency.

[0102] In some PWM modulation methods, PWM modulation is performed in the linear modulation region, overmodulation region 1, and overmodulation region 2. Compared to PWM modulation in the linear modulation region and overmodulation region 1, PWM modulation in overmodulation region 2 can increase the inverter's voltage output capability, thereby increasing the motor speed and reducing the motor's operating current, thereby improving the operating efficiency of the refrigerator compressor.

[0103] However, when the inverter operates in overmodulation zone 2, existing solutions use only the modulation index as a variable in vector allocation to determine the actual voltage vector the inverter needs to output. This approach, which uses only the modulation index as a variable to determine the actual output voltage vector of the inverter, can result in discontinuous voltage output, severe voltage jumps, and increased voltage waveform distortion, further leading to large fluctuations in motor torque.

[0104] The modulation index is the ratio of the reference phase voltage fundamental amplitude to the inverter's maximum output phase voltage fundamental amplitude. Voltage continuity refers to the degree of temporal continuity of the output voltage. Voltage jump refers to a significant change in the output voltage over a short period of time. Voltage waveform distortion refers to the deviation of the output voltage waveform from the ideal waveform (usually a sine wave).

[0105] Based on this, an embodiment of the present application provides a modulation method for an inverter, which determines the voltage vector that the inverter actually needs to output based on the angle value of the target voltage vector and the modulation index, thereby suppressing voltage fluctuations, improving the continuity of the actual output voltage of the inverter, and reducing the degree of output voltage jumps and the voltage waveform distortion rate.

[0106] See also Figure 1 , Figure 1 This is a structural diagram of an inverter provided in an embodiment of the present application;

[0107] like Figure 1 As shown, the inverter 10 includes a capacitor C1, a capacitor C2 and three bridge arms, which are a first bridge arm 11, a second bridge arm 12 and a third bridge arm 13. Each bridge arm includes an upper bridge arm and a lower bridge arm. Figure 1 Taking the example that both the upper bridge arm and the lower bridge arm include a switch tube, the midpoint of each bridge arm is connected to one end of a winding of the motor 20, and the other ends of the three windings of the motor 20 are connected to each other.

[0108] The inverter 10 is connected to a DC power supply (not shown), which provides the capacitors C1 and C2 with Voltage, V dc is the inverter bus voltage (i.e., the DC bus voltage). The DC bus is the common connection point between the DC power supply and the inverter. Capacitors C1 and C2 are both used to smooth the DC voltage and reduce voltage ripple.

[0109] The upper arm of the first bridge arm 11 includes a switch transistor Q11, and the lower arm of the first bridge arm 11 includes a switch transistor Q21. The connection point a between the switches Q11 and Q21 is the midpoint of the first bridge arm 11. The upper arm of the second bridge arm 12 includes a switch transistor Q12, and the lower arm of the second bridge arm 12 includes a switch transistor Q22. The connection point b between the switches Q12 and Q22 is the midpoint of the second bridge arm 12. The upper arm of the third bridge arm 13 includes a switch transistor Q13, and the lower arm of the third bridge arm 13 includes a switch transistor Q23. The connection point c between the switches Q13 and Q23 is the midpoint of the third bridge arm 13. Connection points a, b, and c are respectively connected to the first ends of the three windings of the motor 20, and the second ends of the three windings of the motor 20 are connected to each other.

[0110] Figure 1 For example, each switch tube is an insulated gate bipolar transistor (IGBT). This application does not limit the type of switch tube. In other embodiments, each switch tube can be any controllable switch, such as an integrated gate-commutated thyristor (IGCT), a gate turn-off thyristor (GTO), a silicon controlled rectifier (SCR), a junction field-effect transistor (JFET), a MOS-controlled thyristor (MCT), etc.

[0111] Six switching transistors control the output voltage state of inverter 10. To prevent short circuits, the upper and lower switching transistors in the same bridge arm are complementary. Therefore, determining the switching state of the three switching transistors in the upper bridge arm can determine the operating state of the entire inverter.

[0112] The switch state includes the on state and the off state. The on state is represented by the number 1 and the off state is represented by the number 0. a Indicates the switching state of the switch tube Q11, S b Indicates the switching state of the switch tube Q12, S c Indicates the switching state of the switch tube Q13, using a set of numbers (i.e. S a -S b -S c The specific value of ) can represent all the working states of the inverter.

[0113] The inverter has eight working states: State 0 (at this time S a -S b -S c The values ​​are 000), state 1 (at this time S a -S b -S c The values ​​are 100), state 2 (at this time S a -S b -S c The values ​​are 110 and 110 respectively), state 3 (at this time S a -S b -S c The values ​​are 010), state 4 (at this time S a -S b -S c The values ​​are 011), state 5 (at this time S a -S b -S c The values ​​are 001), state 6 (at this time S a -S b -S c The values ​​are 101 and 7 respectively (at this time S a -S b -S c The values ​​are 111 in sequence).

[0114] Each working state of the inverter corresponds to a basic space vector. The basic space vector refers to the voltage vector with fixed direction and amplitude generated by the different switching states of the inverter. The basic space vectors include zero vectors and non-zero vectors. The zero vector refers to a voltage vector in which all output voltage components are zero, that is, there is no actual voltage output. The non-zero vector refers to a voltage vector with actual voltage output. The basic space vectors corresponding to states 0 and 7 of the inverter are both zero vectors, and the basic space vectors corresponding to the other six working states are all non-zero vectors. The six non-zero vectors divide the space voltage vector plane into 6 sectors. The space voltage vector plane is a two-dimensional plane used to describe the distribution of the basic space vectors of the inverter, for example: the plane where the two-phase stationary coordinate system (i.e., the two-dimensional αβ coordinate system) is located.

[0115] See also Figure 2 , Figure 2 is a schematic diagram of a sector provided in an embodiment of the present application;

[0116] like Figure 2 As shown in the figure, u0 and u7 are zero vectors, and u1, u2, u3, u4, u5, and u6 are non-zero vectors. Every two adjacent non-zero vectors differ by 60 degrees in space. The six non-zero vectors divide the spatial voltage vector plane into six symmetrical sectors (i.e., sector I, sector II, sector III, sector IV, sector V, and sector VI), each with an angle of 60 degrees.

[0117] Among them, u0 is the basic space vector corresponding to state 0, u1 is the basic space vector corresponding to state 1, u2 is the basic space vector corresponding to state 2, u3 is the basic space vector corresponding to state 3, u4 is the basic space vector corresponding to state 4, u5 is the basic space vector corresponding to state 5, u6 is the basic space vector corresponding to state 6, and u7 is the basic space vector corresponding to state 7.

[0118] Space Vector Pulse Width Modulation (SVPWM) is a modulation technique used to control three-phase inverters. It generates a rotating voltage vector in space by appropriately selecting and combining the inverter's switching states. SVPWM technology synthesizes a rotating voltage vector with constant amplitude and continuously changing direction in space. This drives the inverter to output a smooth, continuous voltage waveform, thereby improving the smoothness of motor torque control and, consequently, the operational stability of refrigerator compressors.

[0119] Among them, the rotating voltage vector with constant amplitude and continuously changing direction is used as the given reference voltage vector (for example: Figure 2 u in * ). Since the reference voltage vector u *The eight basic space vectors that can be synthesized at the output of the inverter are evenly distributed in space. Therefore, the SVPWM modulation technology uses the eight basic space vectors u0-u7 to synthesize the reference voltage vector u at different positions. * , so that the voltage vector output by the inverter is a rotating vector with constant amplitude.

[0120] See also Figure 3 , Figure 3 This is a flow chart of a method for controlling an inverter provided in an embodiment of the present application;

[0121] The inverter uses space vector pulse width modulation. The inverter control method is applied to a controller. Specifically, the inverter control method is executed by one or at least two processors in the controller. The controller includes, but is not limited to, a microcontroller unit (MCU) or a digital signal processing (DSP) controller.

[0122] like Figure 3 As shown, the control method of the inverter includes:

[0123] Step S301: obtaining a target voltage vector in each modulation cycle;

[0124] The modulation period is the complete time period of the control signal generated by the controller, that is, the time interval from one starting point to the next identical starting point of the control signal. The control signal is the command signal sent by the controller to the inverter to control the switching state of the inverter's switches. It is a periodic PWM signal generated by the controller based on the synthesized voltage vector. The target voltage vector is the reference voltage vector calculated by the controller based on the desired motor operating state.

[0125] Specifically, the controller collects the stator current of the motor at the beginning of each modulation cycle and determines the target voltage vector based on the stator current of the motor. The stator current is the current flowing through the stator winding of the motor.

[0126] In the embodiment of the present application, the controller uses Field-Oriented Control (FOC) to control the motor. This method collects the motor's stator current and determines the angle of the motor's rotor based on the stator current. This information then generates a PWM signal, which controls the inverter's output of a three-phase AC voltage, thereby controlling the motor's torque.

[0127] It can be understood that the three-phase current output by the inverter flows directly through the stator winding of the motor and can be regarded as the three-phase stator current of the motor.

[0128] See also Figure 4 , Figure 4 1 is a schematic diagram of a controller provided in an embodiment of the present application controlling a motor through a magnetic field oriented control method;

[0129] like Figure 4 As shown, the controller 30 includes a first comparator 301, a speed controller 302, a second comparator 303, a second current regulator 304, a first current regulator 305, a Park inverse converter 306, a space vector modulator 307, a magnetic field weakening controller 308, a third comparator 309, a Park converter 310, a Clark converter 311, and a motor state estimator 312. The controller 30 is connected to the inverter 10 and the motor 20, and the inverter 10 is connected to the motor 20.

[0130] The first comparator 301 is connected to the motor state estimator 309 and the speed controller 302, and is used to compare the input reference speed signal (i.e. Figure 4 Spd_ref in) and the speed estimation signal (i.e. Figure 4 The difference is Spd_est) in the output to obtain a third error signal.

[0131] Among them, the reference speed signal is the speed signal that a person skilled in the art expects the motor to achieve. The reference speed signal can be set by a person skilled in the art according to the application scenario and specific model of the motor, and is not limited here. The speed estimation signal is a signal that reflects the rotation speed of the motor rotor estimated by the motor state estimator 312. The third error signal is a signal obtained by subtracting the reference speed signal from the speed estimation signal at each time point. The first comparator 301 includes but is not limited to a comparator such as a dynamic comparator for generating an error signal.

[0132] The speed controller 302 is connected to the first comparator 301 and the second current regulator 303, and is used to perform proportional control and integral control on the third error signal to obtain the q-axis reference current (i.e. Figure 4 I in q_ref ).

[0133] Proportional control involves multiplying the error signal by a proportional coefficient to generate a proportional term. Integral control involves calculating the integral term based on the historical accumulation of the error signal. The q-axis reference current is the sum of the proportional and integral terms corresponding to the third error signal. Speed ​​controller 301 includes, but is not limited to, a proportional-integral (PI) controller. The formulas used for proportional and integral control are conventional and will not be further described here.

[0134] The second comparator 303 is connected to the speed controller 302 and the second current regulator 304, and is used to compare the input q-axis reference current (i.e. Figure 4 I in q_ref ) and the actual q-axis current (i.e. Figure 4 I in q ) to obtain a second error signal.

[0135] The q-axis actual current is the q-axis current in the two-phase rotating coordinate system output by Park converter 310, and the second error signal is a signal obtained by subtracting the q-axis reference current from the q-axis actual current at each time point. The second comparator 303 includes, but is not limited to, a comparator for generating an error signal, such as a dynamic comparator.

[0136] The second current regulator 304 is connected to the second comparator 303 and the Park inverse converter 306, and is used to perform proportional control and integral control on the second error signal to obtain the q-axis reference voltage (i.e. Figure 4 u in q ).

[0137] The q-axis reference voltage is the sum of the proportional term and the integral term corresponding to the second error signal. The second current regulator 304 includes but is not limited to a proportional-integral (PI) controller.

[0138] The first current regulator 305 is connected to the Park inverse converter 306 and the third comparator 309, respectively, and is used to perform proportional control and integral control on the first error signal to obtain the d-axis reference voltage (i.e. Figure 4 u in d ).

[0139] The first error signal is output by the third comparator 309, and the d-axis reference voltage is the sum of the proportional term and the integral term corresponding to the first error signal. The first current regulator 305 includes but is not limited to a proportional-integral (PI) controller.

[0140] The Park inverse converter 306 is connected to the second current regulator 304, the first current regulator 305, the space vector modulator 307, and the motor state estimator 312, respectively, and is used to generate a current signal according to the angle information of the motor rotor (i.e. Figure 4 Angle in), the q-axis reference voltage in the two-phase rotating coordinate system (i.e. Figure 4 u in q ) and the d-axis reference voltage (i.e. Figure 4 u in d ) to transform the coordinate system and obtain the first voltage component in the two-phase stationary coordinate system (i.e. Figure 4 u in α ) and the second voltage component (ie Figure 4 u inβ ).

[0141] The motor rotor angle information refers to the spatial angle of the motor rotor magnetic field relative to the stator reference system (e.g., a two-phase stationary coordinate system). The first voltage component is the voltage component of the q-axis reference voltage and the d-axis reference voltage in the two-phase rotating coordinate system, along the α-axis of the two-phase stationary coordinate system. The second voltage component is the voltage component of the q-axis reference voltage and the d-axis reference voltage in the two-phase rotating coordinate system, along the β-axis of the two-phase stationary coordinate system.

[0142] The space vector modulator 307 is connected to the Park inverse converter 306 and the inverter 10, respectively, and is used to perform SVPWM modulation on the inverter 10 according to the target voltage vector synthesized by the first voltage component and the second voltage component. For example, when the target voltage vector is in the second overmodulation zone of the inverter, the synthesized voltage vector is calculated based on the angle value of the target voltage vector and the modulation index; and the inverter is controlled to output the synthesized voltage vector.

[0143] The magnetic field weakening controller 308 is connected to the third comparator 309 and the motor state estimator 312 respectively, and is used to estimate the speed of the motor according to the speed estimation signal (ie Figure 4 Spd_est in the d-axis reference current (i.e. Figure 4 I in d_ref The flux weakening controller 308 is a closed-loop control unit that uses a flux weakening control algorithm. The flux weakening control algorithm is a prior art and will not be described in detail herein.

[0144] The third comparator 309 is connected to the first current regulator 305, the weak magnetic controller 308, and the Park converter 310, and is used to compare the input d-axis reference current (i.e. Figure 4 I in d_ref ) and the actual d-axis current (i.e. Figure 4 I in d ) to obtain a first error signal.

[0145] The d-axis actual current is the d-axis current in the two-phase rotating coordinate system output by Park converter 310, and the first error signal is a signal obtained by subtracting the d-axis reference current from the d-axis actual current at each time point. The third comparator 303 includes, but is not limited to, a comparator for generating an error signal, such as a dynamic comparator.

[0146] The Park converter 310 is connected to the third comparator 309, the Clark converter 311, and the motor state estimator 312, respectively, and is used to calculate the motor state according to the angle information of the motor rotor (ie Figure 4 Angle in), for the first current in the two-phase stationary coordinate system (i.e. Figure 4 I in α ) and the second current (ie Figure 4 I in β ) to transform the coordinate system and obtain the actual d-axis current in the two-phase rotating coordinate system (i.e. Figure 4 I in d ) and the actual q-axis current (i.e. Figure 4 I in q ).

[0147] The first current is the current component of the three-phase current output by the inverter in the α-axis direction of the two-phase stationary coordinate system, and the second current is the current component of the three-phase current output by the inverter in the β-axis direction of the two-phase stationary coordinate system.

[0148] The Clark converter 311 is connected to the Park converter 310, the motor state estimator 312, the inverter 10 and the motor 20, and is used to perform a coordinate system transformation on the three-phase current output by the inverter (which can be regarded as the stator current of the motor) to obtain the first current in the two-phase stationary coordinate system (i.e. Figure 4 I in α ) and the second current (ie Figure 4 I in β ).

[0149] Among them, the three-phase current output by the inverter includes the current of phase A (i.e. Figure 4 I in a ), the current of phase B (i.e. Figure 4 I in b ) and the current of phase C (i.e. Figure 4 I in c ).

[0150] The motor state estimator 312 is connected to the first comparator 301, the Park inverse converter 306, the Park converter 310, and the Clark converter 311, and is used to estimate the motor state according to the first voltage component (i.e. Figure 4 u in α ), the second voltage component (i.e. Figure 4 u in β ), the first current (ie Figure 4 I in α ) and the second current (ie Figure 4 I in β ), determine the angle information of the motor rotor (i.e. Figure 4 Angle in) and the speed estimation signal (i.e. Figure 4 Spd_est in ).

[0151] The motor state estimator 312 includes an observer and a phase-locked loop (PLL). The observer estimates the rotor flux or back electromotive force using the first voltage component, the second voltage component, the first current, and the second current in a two-phase stationary coordinate system based on the mathematical model of the motor. The PLL extracts phase information from the flux or back electromotive force output by the observer and determines the angle information and speed estimation signal of the motor rotor using phase synchronization technology. Determining the angle information and speed estimation signal of the motor rotor using the observer and the PLL is a conventional technique and will not be described in detail here.

[0152] In the embodiment of the present application, the target voltage vector is obtained by synthesizing the first voltage component and the second voltage component. For example, the target voltage vector is obtained by synthesizing the first voltage component and the second voltage component using the parallelogram law in a two-phase stationary coordinate system. Step S301 specifically includes steps S311 to S316:

[0153] Step S311: obtaining a d-axis reference current and a q-axis reference current;

[0154] Wherein, the d-axis reference current is given by Figure 4 The d-axis reference current is output by the field weakening controller 308 in the two-phase rotating coordinate system, and is used as the current component along the d-axis (direct axis) direction in the two-phase rotating coordinate system for comparison with the d-axis actual current.

[0155] The q-axis reference current is given by Figure 4 The speed controller 302 outputs the q-axis reference current as a current component along the q-axis (quadrature axis) direction in the two-phase rotating coordinate system for comparison with the q-axis actual current.

[0156] Specifically, the field weakening controller 308 uses a field weakening control algorithm to calculate the required excitation current according to the speed estimation signal output by the motor state estimator 312, and then generates the d-axis reference current.

[0157] The speed controller 302 performs proportional control on the third error signal to obtain a proportional term corresponding to the third error signal, and performs integral control on the third error signal to obtain an integral term corresponding to the third error signal. The proportional term and the integral term corresponding to the third error signal are added to obtain the q-axis reference current.

[0158] The proportional term corresponding to the third error signal is the product of the magnitude of the third error signal and the first proportional coefficient, and the integral term corresponding to the third error signal is the product of the first integral gain and the integral of the third error signal over time. The first proportional coefficient is the proportional coefficient used by speed controller 302, and the first integral gain is the integral gain used by speed controller 302. Those skilled in the art can set the first proportional coefficient and the first integral gain based on the application scenario and are not limited here.

[0159] Step S312: performing coordinate system transformation on the three-phase current output by the inverter to obtain the d-axis actual current and the q-axis actual current in the two-phase rotating coordinate system;

[0160] The d-axis actual current is the current component actually measured along the d-axis (direct axis) in the two-phase rotating coordinate system, and the q-axis actual current is the current component actually measured along the q-axis (quadrature axis) in the two-phase rotating coordinate system.

[0161] Specifically, the three-phase current in the three-phase stationary coordinate system (i.e., the abc coordinate system) output by the inverter is subjected to a Clark transform by the Clark converter 311, and the three-phase current is converted into a first current (i.e., the current component in the α-axis direction) and a second current (i.e., the current component in the β-axis direction) in a two-phase stationary coordinate system (i.e., the α-β coordinate system); the first current and the second current in the two-phase stationary coordinate system are subjected to a Park transform by the Park converter 310 according to the angle information of the motor rotor output by the motor state estimator 312, and the d-axis actual current and the q-axis actual current in the two-phase rotating coordinate system (i.e., the dq coordinate system) are obtained.

[0162] The formula for converting the three-phase current in a three-phase stationary coordinate system into the first current and the second current in a two-phase stationary coordinate system using the Clark transform is prior art and will not be repeated here. The formula for converting quantities in a two-phase stationary coordinate system into quantities in a two-phase rotating coordinate system using the Park transform based on the angle information of the motor rotor is prior art and will not be repeated here.

[0163] Step S313: Calculating a first error signal between the d-axis reference current and the d-axis actual current, and a second error signal between the q-axis reference current and the q-axis actual current;

[0164] Specifically, the third comparator 309 subtracts the d-axis reference current from the d-axis actual current at each time point to obtain a first error signal, and the second comparator 303 subtracts the q-axis reference current from the q-axis actual current at each time point to obtain a second error signal.

[0165] Step S314: performing proportional control and integral control on the first error signal through the first current regulator to obtain a d-axis reference voltage in a two-phase rotating coordinate system;

[0166] Specifically, the first current regulator 305 performs proportional control on the first error signal to obtain a proportional term corresponding to the first error signal, and performs integral control on the first error signal to obtain an integral term corresponding to the first error signal. The proportional term and the integral term corresponding to the first error signal are added to obtain the d-axis reference voltage.

[0167] The proportional term corresponding to the first error signal is the product of the magnitude of the first error signal and the second proportional coefficient, and the integral term corresponding to the first error signal is the product of the second integral gain and the integral of the first error signal over time. The second proportional coefficient is the proportional coefficient used by first current regulator 305, and the second integral gain is the integral gain used by first current regulator 305. Those skilled in the art can set the second proportional coefficient and second integral gain based on the application scenario and are not limited here.

[0168] Step S315: performing proportional control and integral control on the second error signal through the second current regulator to obtain a q-axis reference voltage in a two-phase rotating coordinate system;

[0169] Specifically, the second current regulator 304 performs proportional control on the second error signal to obtain a proportional term corresponding to the second error signal, and performs integral control on the second error signal to obtain an integral term corresponding to the second error signal. The proportional term and the integral term corresponding to the second error signal are added to obtain the q-axis reference voltage.

[0170] The proportional term corresponding to the second error signal is the product of the magnitude of the second error signal and the third proportional coefficient, and the integral term corresponding to the second error signal is the product of the third integral gain and the integral of the second error signal over time. The third proportional coefficient is the proportional coefficient used by second current regulator 304, and the third integral gain is the integral gain used by second current regulator 304. Those skilled in the art can set the third proportional coefficient and third integral gain based on the application scenario and are not limited here.

[0171] Step S316 : performing coordinate transformation on the d-axis reference voltage and the q-axis reference voltage to obtain a first voltage component and a second voltage component in a two-phase stationary coordinate system.

[0172] Specifically, the Park inverse transformer 306 performs a Park inverse transform on the q-axis reference voltage and the d-axis reference voltage in the two-phase rotating coordinate system according to the angle information of the motor rotor output by the motor state estimator 312, and obtains the first voltage component (i.e., the voltage component in the α-axis direction) and the second voltage component (i.e., the voltage component in the β-axis direction) in the two-phase stationary coordinate system.

[0173] Among them, the formula for converting the quantity in the two-phase rotating coordinate system to the two-phase stationary coordinate system through Park inverse transformation based on the angle information of the motor rotor is an existing technology and will not be repeated here.

[0174] In an embodiment of the present application, before step S301 , the method further includes: dividing the modulation region of the inverter into a linear modulation region, a first overmodulation region, and a second overmodulation region according to the modulation range of the target voltage vector.

[0175] The modulation range is the range of the modulation index of the target voltage vector, and the modulation index is the ratio of the target voltage vector amplitude to the maximum phase voltage fundamental amplitude output by the inverter. It can be understood that the target voltage vector amplitude is the voltage value that the controller expects to be applied to the inverter bridge arm, which is also referred to as the reference phase voltage fundamental amplitude above.

[0176] The maximum phase voltage fundamental amplitude output by the inverter is the maximum amplitude of the fundamental part of the phase voltage output by the inverter in the six-step square wave mode. The six-step square wave mode means that the inverter executes six non-zero vectors (i.e., u1-u6) in sequence in each modulation cycle, and only outputs one of the non-zero vectors at a time, thereby forming a periodic square wave waveform. The maximum phase voltage fundamental amplitude output by the inverter can be determined by performing Fourier analysis on the output voltage of the inverter. Fourier analysis is a mathematical tool for decomposing complex periodic signals into several simple sinusoidal wave components. The method of determining the maximum phase voltage fundamental amplitude output by the inverter by Fourier analysis is a prior art and will not be repeated here. For example, the maximum phase voltage fundamental amplitude output by the inverter is Among them, V dc The bus voltage value of the inverter, i.e., the DC bus voltage, can be set by those skilled in the art according to the application scenario and is not limited here.

[0177] The linear modulation area corresponds to the first modulation range, the overmodulation area 1 corresponds to the second modulation range, and the overmodulation area 2 corresponds to the third modulation range. The first modulation range is the modulation index ∈(0, first preset value], the second modulation range is the modulation index ∈(first preset value, second preset value], and the third modulation range is the modulation index ∈(second preset value, 1]. The first preset value is greater than 0, the first preset value is less than the second preset value, and the second preset value is less than 1.

[0178] The vector endpoints of the six non-zero vectors are connected in sequence to form a regular hexagon. The target voltage vector consists of a starting point and an end point, the starting point is the origin of the coordinate system, and the end point is the position pointed to by the target voltage vector. The first preset value is the modulation index when the end point of the target voltage vector is on the inscribed circle of the regular hexagon. The second preset value is the modulation index when the end point of the target voltage vector is on the boundary of the regular hexagon. The first preset value can be calculated by the calculation formula of the modulation index, and the second preset value can be determined by those skilled in the art according to the volt-second balance principle. The volt-second balance principle refers to ensuring that the total electrical energy (expressed in volt-seconds) generated by the voltage vector output by the inverter in the motor within a certain period of time matches the electrical energy expected to be generated by the target voltage vector by controlling the duration and amplitude of the inverter output voltage vector. By way of example, the first preset value is 0.906 and the second preset value is 0.952.

[0179] Specifically, the modulation area corresponding to the first modulation range is used as the linear modulation area, the modulation area corresponding to the second modulation range is used as the overmodulation area 1, and the modulation area corresponding to the third modulation range is used as the overmodulation area 2.

[0180] Please refer again Figure 3 ,like Figure 3 As shown, the vector endpoints of multiple non-zero vectors are sequentially connected to form a regular hexagon, and the regular hexagon has an inscribed circle.

[0181] In the linear modulation area, the target voltage vector is located at the boundary and inner area of ​​the inscribed circle. When the end point of the target voltage vector is located at the boundary of the inscribed circle, the PWM linear modulation reaches its maximum output limit. At this time, the reference phase voltage fundamental amplitude is The first preset value is That is, when the modulation index ∈ (0, 0.906], the target voltage vector can be actually output by linearly combining two adjacent basic space vectors (u0-u6). The output voltage vector in the linear modulation area shows a linear relationship and is continuous without jumps.

[0182] In the overmodulation zone 1, the endpoint of the target voltage vector is outside the boundary of the inscribed circle, and there are cases where the endpoint of the target voltage vector is outside the boundary of the regular hexagon. Because the maximum output voltage vector range of the overmodulation zone 1 is the boundary of the regular hexagon, the vector portion outside the boundary of the regular hexagon cannot be actually output by the inverter. In this case, the existing solution shortens the vector portion of the target voltage vector outside the boundary of the regular hexagon to the boundary of the hexagon by maintaining the direction of the target voltage vector unchanged. That is, the endpoint of the target voltage vector is moved along the original direction to the boundary of the regular hexagon, so that the endpoint of the actual output voltage vector is confined within the boundary of the regular hexagon.

[0183] At the same time, volt-second compensation is achieved by increasing the amplitude of the voltage vector within the regular hexagon until the endpoints of all actual output voltage vectors fall on the hexagon boundaries, reaching the maximum output limit of overmodulation zone 1. According to the volt-second balance principle, the modulation index at this point is the second preset value, i.e., 0.952. In other words, when the modulation index reaches the second preset value, the maximum boundary of the actual output voltage vector falls on the boundary of the regular hexagon, and the output voltage vectors within overmodulation zone 1 exhibit a nonlinear relationship, but remain continuous and without jumps.

[0184] It can be understood that within the first overmodulation region, the vector portion outside the boundaries of the regular hexagon is shortened to the boundary of the regular hexagon while maintaining its direction. The vector portion that cannot be actually output by the inverter is compensated in volt-seconds by the basic space vectors that have not yet reached the boundary of the regular hexagon. At this time, all the vector portions that cannot be output can be filled with all the voltage vectors that do not exceed the boundary of the regular hexagon. Therefore, the continuity of the output voltage can be maintained.

[0185] In the second overmodulation zone, the target voltage vector's endpoint lies outside the boundaries of the regular hexagon. The portion of the vector outside the boundaries of the regular hexagon is beyond the compensable range and cannot be fully compensated by the voltage vectors within the regular hexagon. Consequently, the target voltage vector can no longer be distributed continuously across the entire boundary of the regular hexagon. Existing solutions can only compensate by shifting the output time originally allocated to the shorter voltage vector to the longer voltage vector, but this approach results in discontinuous voltage output from the inverter.

[0186] Step S302: when the target voltage vector is in the second overmodulation region of the inverter, calculating a synthetic voltage vector according to the angle value of the target voltage vector and the modulation index;

[0187] The angle value of the target voltage vector is the angle formed by the target voltage vector and the α axis of the two-phase stationary coordinate system. The resultant voltage vector is the voltage vector that the inverter actually needs to output.

[0188] Specifically, when the target voltage vector is in the second overmodulation zone of the inverter, the angle range of the target voltage vector is determined according to the angle value of the target voltage vector and the modulation index, and different strategies are adopted according to different angle ranges to calculate the synthetic voltage vector.

[0189] In an embodiment of the present application, before step S302 , the method further includes: calculating a modulation index based on the target voltage vector; and determining that the target voltage vector is in the second overmodulation zone when the modulation index is greater than a second preset value.

[0190] Specifically, the modulation index is calculated using the following formula:

[0191]

[0192] Among them, MI represents the modulation index, u α represents the first voltage component of the target voltage vector in the α-axis direction of the two-phase stationary coordinate system, u β The second voltage component of the target voltage vector in the β-axis direction of the two-phase stationary coordinate system, V dc Indicates the bus voltage value of the inverter.

[0193] Furthermore, the modulation index is compared with a second preset value. When the modulation index is greater than the second preset value, it is determined that the target voltage vector is in overmodulation region 2. It will be appreciated that when the modulation index is less than or equal to the second preset value, the target voltage vector is in the linear modulation region or overmodulation region 1.

[0194] In the embodiment of the present application, step S302 specifically includes steps S321 to S326:

[0195] Step S321: determining the sector where the target voltage vector is located, and dividing the sector into two angle intervals;

[0196] Each sector corresponds to a different sector angle. The sector angle is the angular range between the boundaries of two adjacent sectors on a circle. The sector angle consists of the sector's starting and ending angles. For example, the sector angle of sector I is [0°, 60°), the sector angle of sector II is [60°, 120°), the sector angle of sector III is [120°, 180°), the sector angle of sector IV is [180°, 240°), the sector angle of sector V is [240°, 300°), and the sector angle of sector VI is [300°, 360°]. The angle interval refers to the angular range corresponding to each sub-region when a sector is divided into two sub-regions.

[0197] Specifically, the sector where the target voltage vector is located and the center angle of the sector are determined, and the sector is divided into two angle intervals based on the center angle. The center angle of the sector is the average of the sector's starting angle and ending angle. The two angle intervals include a first angle interval and a second angle interval. The first angle interval is [sector's starting angle, sector's center angle), and the second angle interval is [sector's center angle, sector's ending angle).

[0198] For example: for sector I, the center angle is 30°, the first angle interval is [0°, 30°), and the second angle interval is [30°, 60°).

[0199] In some embodiments, the step of determining the sector where the target voltage vector is located includes: calculating the angle value of the target voltage vector, and taking the sector corresponding to the sector angle to which the angle value of the target voltage vector belongs as the sector where the target voltage vector is located.

[0200] In some embodiments, the step of determining the sector where the target voltage vector is located includes: determining the sector where the target voltage vector is located based on a sign and magnitude relationship between a first voltage component and a second voltage component of the target voltage vector in a two-phase stationary coordinate system.

[0201] Specifically, in u α >0, and u β >0, and When the target voltage vector is located in the sector I, the sector I is determined to be the target voltage vector; α <0, and u β >0, and When the target voltage vector is located in the sector II, the sector II is determined; α <0, and u β >0, and When the target voltage vector is located in the sector III, the sector III is determined; α <0, and u β <0, and , the sector where the target voltage vector is located is determined to be sector IV.

[0202] in u α >0, and u β <0, and When the target voltage vector is located in sector V, the sector V is determined; α >0, and u β <0, and When , the sector where the target voltage vector is located is determined to be sector VI. α represents the first voltage component of the target voltage vector in the α-axis direction of the two-phase stationary coordinate system, u β Represents the second voltage component of the target voltage vector in the β-axis direction of the two-phase stationary coordinate system.

[0203] Step S322: Calculate the angle value of the target voltage vector, and determine the angle interval of the target voltage vector according to the angle value;

[0204] Specifically, the angle value of the target voltage vector is calculated using the following formula:

[0205]

[0206] Where θ represents the angle value of the target voltage vector, u β The second voltage component of the target voltage vector in the β-axis direction of the two-phase stationary coordinate system, u α Represents the first voltage component of the target voltage vector in the α-axis direction of the two-phase stationary coordinate system.

[0207] Further, the angle value of the target voltage vector is compared with the center angle of the sector determined in step S321. When the angle value of the target voltage vector is less than the center angle of the sector, the angle interval in which the target voltage vector is located is determined to be the first angle interval. When the angle value of the target voltage vector is greater than or equal to the center angle of the sector, the angle interval in which the target voltage vector is located is determined to be the second angle interval.

[0208] The angle interval is a range from a first angle to a second angle, where the first angle is smaller than the second angle. When the target voltage vector is within the first angle interval, the first angle is the starting angle of the sector, and the second angle is the center angle of the sector. When the target voltage vector is within the second angle interval, the first angle is the center angle of the sector, and the second angle is the ending angle of the sector.

[0209] Step S323: Calculating a first proportional coefficient according to the modulation index;

[0210] The first proportional coefficient is a coefficient calculated according to the modulation index and the second preset value.

[0211] Specifically, the first proportional coefficient is calculated by the following formula:

[0212]

[0213] Wherein, P1 represents the first proportional coefficient, MI represents the modulation index, and a represents the second preset value.

[0214] Exemplarily, when the second preset value is 0.952, the modulation range corresponding to the second overmodulation zone is (0.952, 1], and the value range of the first proportional coefficient is [0, 1].

[0215] Step S324: multiplying the first proportional coefficient by the second angle to obtain a third angle;

[0216] The third angle is the product of the first proportional coefficient and the second angle. The third angle is greater than the first angle and smaller than the second angle.

[0217] Step S325: When the angle value of the target voltage vector is greater than or equal to the first angle and the angle value of the target voltage vector is less than the third angle, calculating a synthetic voltage vector according to the first proportional coefficient, the basic space vector, and the target voltage vector;

[0218] Specifically, the target voltage vector angle is compared with the third angle. If the target voltage vector angle is less than the third angle, a composite voltage vector is calculated based on the first proportionality factor, the basic space vector, and the target voltage vector. If the target voltage vector angle is greater than or equal to the third angle, the process proceeds to step S326.

[0219] In the embodiment of the present application, step S325 specifically includes steps S3251 to S3253:

[0220] Step S3251: scaling the target voltage vector to the boundary of a regular hexagon to obtain a first vector;

[0221] The first vector has the same direction as the target voltage vector, and the first vector is a vector obtained by scaling the target voltage vector, with its end point located on the boundary of the regular hexagon.

[0222] Specifically, the starting point and direction of the target voltage vector are kept unchanged, and the length (ie, amplitude) of the target voltage vector is scaled so that the end point of the target voltage vector is located on the boundary of the regular hexagon. The target voltage vector obtained at this time is used as the first vector.

[0223] For example: calculate the maximum voltage vector length, divide the maximum voltage vector length by the amplitude of the target voltage vector to obtain a scaling ratio, multiply the scaling ratio by the first voltage component to obtain a third voltage component, multiply the scaling ratio by the second voltage component to obtain a fourth voltage component, and synthesize the third voltage component and the fourth voltage component using the parallelogram rule to obtain the first vector.

[0224] The maximum voltage vector length is the distance from the vertex to the center of the regular hexagon. The target voltage vector amplitude is the square root of the sum of the squares of the first and second voltage components. The third voltage component is the voltage component of the first vector on the α-axis in the two-phase stationary coordinate system, and the fourth voltage component is the voltage component of the first vector on the β-axis in the two-phase stationary coordinate system. The formulas for calculating the maximum voltage vector length and the target voltage vector amplitude, as well as the vector synthesis using the parallelogram rule, are all known techniques and are not detailed here.

[0225] Step S3252: Determine the angle between the target voltage vector and each non-zero vector, and use the non-zero vector with the smallest angle as the second vector;

[0226] The second vector is a non-zero vector having the smallest angle with the target voltage vector.

[0227] Specifically, the angle value between the target voltage vector and each non-zero vector is calculated to obtain several angle values, the several angle values ​​are sorted to determine the minimum angle value, and the non-zero vector corresponding to the minimum angle value is used as the second vector.

[0228] Step S3253: Calculate a composite voltage vector according to the first vector, the second vector and the first proportional coefficient.

[0229] Specifically, the synthetic voltage vector is calculated using the following formula:

[0230] Vreal=(1-P1)*V1+P1*V2

[0231] Wherein, Vreal represents the resultant voltage vector, P1 represents the first proportional coefficient, V1 represents the first vector, and V2 represents the second vector.

[0232] If the angle value of the target voltage vector is not considered and only the modulation index is used as a variable to determine the actual output voltage vector of the inverter, that is, only the formula in step S3253 is used to calculate the synthetic voltage vector, the following three situations may occur:

[0233] In the first case, when the modulation index is the second preset value (ie, 0.952), P1=0. At this time, Vreal=V1, and the end point of the synthetic voltage vector is located on the boundary of the regular hexagon, that is, the inverter can control the synthetic voltage vector to be output along the boundary of the regular hexagon.

[0234] In the second case, when the modulation index is 1, P1=1, at this time, Vreal=V2, the inverter can only select one non-zero vector output at a time, and synthesize the required output voltage vector by quickly switching six non-zero vectors. At this time, the inverter has reached its designed maximum voltage output capability.

[0235] In the third case, when the modulation index is an intermediate value, for example, 0.975, P1 = 0.023 / 0.048 = 0.479, and Vreal = 0.521*V1+0.479*V2. In this case, due to the addition of V2 as the output component, Vreal deviates from V1 in both amplitude and phase. Especially in the center of each sector, the actual output vector cannot accurately locate the target voltage vector. As a result, the actual output vector exhibits nonlinearity, discontinuity, and even jumps in this region.

[0236] It can be seen that using only the modulation index as a variable in vector allocation to determine the voltage vector that the inverter actually needs to output will result in discontinuous voltage, severe voltage jumps, and increased voltage waveform distortion.

[0237] Therefore, the present application introduces the angle value of the target voltage vector as a correction coefficient, and adopts different strategies to calculate the synthetic voltage vector according to different angle ranges of the target voltage vector.

[0238] Step S326: When the angle value of the target voltage vector is greater than or equal to the third angle and the angle value of the target voltage vector is less than the second angle, a second proportional coefficient is calculated based on the first proportional coefficient, and a composite voltage vector is calculated based on the first proportional coefficient, the second proportional coefficient, the basic space vector, and the target voltage vector.

[0239] The second proportional coefficient is a coefficient calculated according to the first proportional coefficient, the angle value of the target voltage vector, the second angle, and the third angle.

[0240] Specifically, when the angle value of the target voltage vector is greater than or equal to the third angle and the angle value of the target voltage vector is less than the second angle, the second proportional coefficient is first calculated based on the first proportional coefficient, and then the synthetic voltage vector is calculated based on the first proportional coefficient, the second proportional coefficient, the basic space vector, and the target voltage vector.

[0241] In the embodiment of the present application, the step of calculating the second proportional coefficient according to the first proportional coefficient includes steps S3261 to S3263:

[0242] Step S3261: taking the difference between the second angle and the third angle as the first difference;

[0243] The first difference is the difference between the second angle and the third angle.

[0244] Step S3262: taking the difference between the second angle and the angle value of the target voltage vector as a second difference value;

[0245] The second difference is the difference between the second angle and the angle value of the target voltage vector.

[0246] Step S3263: Calculate a second proportional coefficient according to the first proportional coefficient, the first difference, and the second difference.

[0247] Specifically, the second proportional coefficient is calculated by the following formula:

[0248]

[0249] Wherein, P2 represents the second proportional coefficient, θ1 represents the first difference, θ2 represents the second difference, and P1 represents the first proportional coefficient.

[0250] In the embodiment of the present application, the step of calculating the synthetic voltage vector according to the first proportional coefficient, the second proportional coefficient, the basic space vector, and the target voltage vector includes steps S3264 to S3266:

[0251] Step S3264: scaling the target voltage vector to the boundary of the regular hexagon to obtain a first vector;

[0252] The first vector has the same direction as the target voltage vector, and the first vector is a vector obtained by scaling the target voltage vector, with its end point located on the boundary of the regular hexagon.

[0253] Specifically, the starting point and direction of the target voltage vector are kept unchanged, and the length (ie, amplitude) of the target voltage vector is scaled so that the end point of the target voltage vector is located on the boundary of the regular hexagon. The target voltage vector obtained at this time is used as the first vector.

[0254] The specific implementation of this step is the same as that of step S3251 and will not be repeated here.

[0255] Step S3265: Determine the angle between the target voltage vector and each non-zero vector, and use the non-zero vector with the smallest angle as the second vector;

[0256] The second vector is a non-zero vector having the smallest angle with the target voltage vector.

[0257] Specifically, the angle value between the target voltage vector and each non-zero vector is calculated to obtain several angle values, the several angle values ​​are sorted to determine the minimum angle value, and the non-zero vector corresponding to the minimum angle value is used as the second vector.

[0258] Step S3266: Calculate a composite voltage vector according to the first vector, the second vector, the first proportional coefficient, and the second proportional coefficient.

[0259] Specifically, the synthetic voltage vector is calculated using the following formula:

[0260] Vreal=(1-P2)*V1+P1*V2

[0261] Wherein, Vreal represents the resultant voltage vector, P2 represents the second proportional coefficient, V1 represents the first vector, P1 represents the first proportional coefficient, and V2 represents the second vector.

[0262] See also Figure 5 , Figure 5 is a schematic diagram of an angle interval provided in an embodiment of the present application;

[0263] Figure 5 Taking sector I as an example, the other sectors are similar and will not be described here.

[0264] like Figure 5 As shown, the target voltage vector u * The sector is sector I, the center angle of sector I is 30°, and sector I is divided into two angle intervals: the first angle interval is [0°, 30°), and the second angle interval is [30°, 60°]. When the angle interval where the target voltage vector is located is the first angle interval, the first angle is 0°, the second angle is 30°, and the third angle θ0 is P1*30°.

[0265] When the angle value θ of the target voltage vector is greater than or equal to 0° and the angle value of the target voltage vector is less than the third angle θ0, the composite voltage vector is calculated according to the formula in step S325.

[0266] When the angle value θ of the target voltage vector is greater than or equal to the third angle θ0 and the angle value of the target voltage vector is less than 30°, the first difference θ1 is 30°-θ0, and the second difference θ2 is 30°-θ.

[0267] According to the formula for calculating the synthesized voltage vector in step S3266, it can be seen that: when the target voltage vector angle θ is 30°, P1 = 0, P2 = 0, and Vreal = V1, the inverter can actually output a voltage vector in the 30° direction. As θ gradually approaches θ0, according to the formula in step S325, the output ratio of V2 increases with the increase in angle. That is, as θ gradually approaches θ0, the value of P2 gradually increases. In the formula Vreal = (1-P2)*V1+P1*V2, the contribution of V1 gradually decreases, while the contribution of V2 gradually increases. Therefore, the actual output voltage of the inverter can be made continuous, and the degree of output voltage jump and voltage waveform distortion rate can be reduced.

[0268] In an embodiment of the present application, by determining the voltage vector that the inverter actually needs to output based on the angle value of the target voltage vector and the modulation index in the overmodulation zone 2, on the one hand, it is possible to suppress voltage fluctuations, improve the continuity of the actual output voltage of the inverter, reduce the harmonic content of the output voltage, reduce the jump degree of the output voltage and the voltage waveform distortion rate, thereby reducing the fluctuation of the motor stator current, improving the smoothness of the motor torque control, and thereby improving the operating efficiency of the refrigerator compressor and enhancing the operating stability of the refrigerator compressor; on the other hand, the method is simple and has a small amount of calculation, which is convenient for the controller to perform online real-time calculations.

[0269] Step S303: controlling the inverter to output a synthetic voltage vector.

[0270] Specifically, the controller calculates the on-time of each switch tube according to the synthesized voltage vector, thereby generating a periodic control signal (ie, a PWM signal), and sends the control signal to the inverter to enable the inverter to output the synthesized voltage vector.

[0271] The control signal is a command signal sent by the controller to the inverter to control the switching state of the inverter's switches. It is also a periodic PWM signal generated by the controller based on the synthesized voltage vector. Calculating the on-time of the switches based on the voltage vector and generating the periodic PWM signal accordingly is a prior art technique and will not be further elaborated here.

[0272] In an embodiment of the present application, a modulation method for an inverter is provided, in which the inverter adopts a space vector pulse width modulation method. The modulation method for the inverter includes: obtaining a target voltage vector in each modulation cycle; when the target voltage vector is in the second overmodulation zone of the inverter, calculating a synthetic voltage vector based on the angle value of the target voltage vector and the modulation index; and controlling the inverter to output the synthetic voltage vector.

[0273] By obtaining the target voltage vector in each modulation cycle, when the target voltage vector is in the second overmodulation zone of the inverter, the synthetic voltage vector is calculated according to the angle value and modulation index of the target voltage vector, and the inverter is controlled to output the synthetic voltage vector. The present application can determine the voltage vector that the inverter actually needs to output according to the angle value and modulation index of the target voltage vector, suppress voltage fluctuations, improve the continuity of the actual output voltage of the inverter, and reduce the degree of output voltage jump and the voltage waveform distortion rate.

[0274] See also Figure 6 , Figure 6 This is a structural diagram of a modulation device for an inverter provided in an embodiment of the present application;

[0275] The modulation device of the inverter is applied to a controller, specifically, the modulation device of the inverter is applied to one or at least two processors of the controller. The inverter adopts space vector pulse width modulation.

[0276] like Figure 6 As shown, the modulation device 600 of the inverter includes:

[0277] The acquisition unit 601 is configured to acquire a target voltage vector in each modulation period.

[0278] The calculation unit 602 is configured to calculate a synthetic voltage vector according to the angle value of the target voltage vector and the modulation index when the target voltage vector is in the second overmodulation region of the inverter.

[0279] The output unit 603 is used to control the inverter to output a synthetic voltage vector.

[0280] In the embodiments of the present application, the modulation device of the inverter can also be constructed by hardware devices. For example, the modulation device of the inverter can be constructed by one or more chips, and the chips can work in coordination with each other to complete the modulation method of the inverter described in the above embodiments. For another example, the modulation device of the inverter can also be constructed by various logic devices, such as a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), a single-chip microcomputer, an ARM processor (Advanced RISC Machines, ARM) or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combination of these components.

[0281] The modulation device of the inverter in the embodiment of the present application may be a device having an operating system. The operating system may be an Android operating system, an iOS operating system, or other possible operating systems, which are not specifically limited in the embodiment of the present application.

[0282] The modulation device of the inverter provided in the embodiment of the present application can achieve Figure 3 To avoid repetition, the various implementation processes will not be described here.

[0283] It should be noted that the inverter modulation device described above can execute the inverter modulation method provided in the above embodiments and has the corresponding functional modules and beneficial effects of executing the method. For technical details not fully described in the inverter modulation device embodiment, please refer to the inverter modulation method provided in the above embodiments.

[0284] In an embodiment of the present application, a modulation device for an inverter is provided, and the inverter adopts a space vector pulse width modulation method. The modulation device of the inverter includes: an acquisition unit, which is used to obtain a target voltage vector in each modulation cycle; a calculation unit, which is used to calculate a synthetic voltage vector based on the angle value and modulation index of the target voltage vector when the target voltage vector is in the second overmodulation zone of the inverter; and an output unit, which is used to control the inverter to output the synthetic voltage vector.

[0285] The present application can determine the voltage vector that the inverter actually needs to output based on the angle value of the target voltage vector and the modulation index, suppress voltage fluctuations, improve the continuity of the actual output voltage of the inverter, and reduce the output voltage jump degree and voltage waveform distortion rate.

[0286] See also Figure 7 , Figure 7 This is a schematic diagram of the structure of a controller provided in an embodiment of the present application;

[0287] like Figure 7 As shown, the controller 30 includes one or more processors 31 and a memory 32. Figure 7 A processor 31 is taken as an example.

[0288] The processor 31 and the memory 32 may be connected via a bus or other means. Figure 7 The bus connection is taken as an example.

[0289] The processor 31 is used to provide computing and control capabilities to control the controller 30 to perform corresponding tasks, for example, to control the controller 30 to perform the modulation method of the inverter in any of the above method embodiments.

[0290] The processor 31 includes a first comparator 301 , a speed controller 302 , a second comparator 303 , a second current regulator 304 , a first current regulator 305 , a Park inverse converter 306 , a space vector modulator 307 , a flux weakening controller 308 , a third comparator 309 , a Park converter 310 , a Clark converter 311 and a motor state estimator 312 .

[0291] The processor 31 may be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), a hardware chip, or any combination thereof; it may also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or any combination thereof. The PLD may be a complex programmable logic device (CPLD), a field-programmable gate array (FPGA), a generic array logic (GAL), or any combination thereof.

[0292] The memory 32 is a non-transitory computer-readable storage medium that can be used to store non-transitory software programs, non-transitory computer executable programs and modules, such as the program instructions / modules corresponding to the modulation method of the inverter in the embodiment of the present application. The processor 31 can implement the modulation method of the inverter in any of the above method embodiments by running the non-transitory software programs, instructions and modules stored in the memory 32. Specifically, the memory 32 may include a volatile memory (VM), such as a random access memory (RAM); the memory 32 may also include a non-volatile memory (NVM), such as a read-only memory (ROM), a flash memory, a hard disk drive (HDD) or a solid-state drive (SSD) or other non-transitory solid-state storage device; the memory 32 may also include a combination of the above types of memories.

[0293] The memory 32 may include high-speed random access memory and non-volatile memory, such as at least one disk storage device, flash memory device, or other non-volatile solid-state memory device. In some embodiments, the memory 32 may optionally include a memory remotely located relative to the processor 31, and such remote memory may be connected to the processor 31 via a network. Examples of such networks include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0294] One or more modules are stored in the memory 32, and when executed by one or more processors 31, the modulation method of the inverter in any of the above method embodiments is executed, for example, the modulation method described above is executed. Figure 3 The steps shown.

[0295] In the embodiment of the present application, the controller 30 may also have components such as a wired or wireless network interface, an input and output interface, etc., for input and output. The controller 30 may also include other components for realizing the functions of the device, which will not be described in detail here.

[0296] See also Figure 8 , Figure 8 This is a schematic structural diagram of a drive system provided in an embodiment of the present application;

[0297] like Figure 8 As shown, the drive system 800 includes a controller 30 and an inverter 10. The controller 30 is connected to the inverter 10, and the inverter adopts a space vector pulse width modulation method.

[0298] The controller 30 is configured to execute the modulation method of the inverter in any of the above embodiments, for example, obtaining a target voltage vector in each modulation cycle; calculating a synthetic voltage vector based on the angle value of the target voltage vector and the modulation index when the target voltage vector is in the second overmodulation zone of the inverter; and controlling the inverter to output the synthetic voltage vector.

[0299] Inverter 10 is connected to controller 30 and is configured to convert DC power into AC power based on a control signal sent by controller 30. The control signal is a command signal sent by the controller to the inverter to control the switching state of the inverter's switches. This signal is a periodic PWM signal generated by the controller based on the synthesized voltage vector.

[0300] In an embodiment of the present application, a drive system is provided, comprising: a controller configured to execute the inverter modulation method described in any of the above embodiments; and an inverter connected to the controller configured to convert direct current (DC) power into alternating current (AC) power based on a control signal sent by the controller. This application can improve the continuity of the inverter's actual output voltage and reduce the degree of output voltage fluctuations and voltage waveform distortion.

[0301] See also Figure 9 , Figure 9 This is a schematic structural diagram of a refrigerator compressor provided in an embodiment of the present application;

[0302] like Figure 9 As shown, the refrigerator compressor 900 includes a drive system 800 and a motor 20. The drive system 800 is connected to the motor 20.

[0303] The drive system 800 includes a controller 30 and an inverter 10. The controller 30 is used to execute the modulation method of the inverter in any of the above embodiments, and the inverter 10 is used to convert direct current into alternating current according to a control signal sent by the controller 30.

[0304] Motor 20, connected to drive system 800, is used to convert alternating current into mechanical energy. Motors include, but are not limited to, permanent magnet synchronous motors (PMSMs). The PMSM operates by using permanent magnets to generate a magnetic field on the rotor. When three-phase current flows through the stator windings, a rotating magnetic field is generated. This rotating magnetic field interacts with the magnetic field of the permanent magnets on the rotor, generating synchronously rotating electromagnetic torque, thereby driving the motor rotor.

[0305] In an embodiment of the present application, a refrigerator compressor is provided, comprising a drive system and a motor, wherein the drive system comprises a controller and an inverter, wherein the controller is configured to execute the inverter modulation method described in any of the above embodiments, the inverter is configured to convert direct current into alternating current according to a control signal sent by the controller, and the motor is configured to convert the alternating current into mechanical energy. The present application can improve the continuity of the actual output voltage of the inverter, reduce the degree of jumps in the output voltage and the voltage waveform distortion rate, thereby reducing the fluctuation of the motor stator current and improving the smoothness of the motor torque control, thereby improving the operating efficiency and operational stability of the refrigerator compressor.

[0306] The embodiment of the present application further provides a non-volatile computer-readable storage medium, wherein the non-volatile computer-readable storage medium stores computer-executable instructions. When the computer-executable instructions are executed by a processor, the processor executes the modulation method of the inverter in any of the above embodiments, for example, Figure 3 The modulation method of the inverter is shown.

[0307] In the embodiment of the present application, the storage medium can be a memory such as FRAM, ROM, PROM, EPROM, EE PROM, flash memory, magnetic surface memory, optical disk, or CD-ROM; or it can be various devices including one or any combination of the above memories.

[0308] In an embodiment of the present application, executable instructions may be in the form of a program, software, software module, script or code, written in any form of programming language (including compiled or interpreted languages, or declarative or procedural languages), and may be deployed in any form, including as a standalone program or as a module, component, subroutine or other unit suitable for use in a computing environment.

[0309] As an example, executable instructions may, but need not, correspond to a file in a file system, may be stored as part of a file that stores other programs or data, such as, for example, in one or more scripts in a HyperText Markup Language (HTML) document, in a single file dedicated to the program in question, or in multiple coordinating files (e.g., files storing one or more modules, subroutines, or code portions).

[0310] As an example, executable instructions may be deployed to be executed on a computing device (including devices such as smart terminals and servers), or on multiple computing devices located in one location, or on multiple computing devices distributed in multiple locations and interconnected by a communication network.

[0311] The present application also provides a computer program product comprising one or more program codes stored in a non-volatile computer-readable storage medium. A processor of a controller reads the program code from the non-volatile computer-readable storage medium and executes the program code to perform the steps of the inverter modulation method provided in the above-described embodiment.

[0312] Those skilled in the art will understand that all or part of the steps for implementing the above embodiments may be accomplished by hardware, or by hardware related to program code, and the program may be stored in a non-volatile computer-readable storage medium. The non-volatile computer-readable storage medium mentioned above may be a read-only memory, a disk, or an optical disk, etc.

[0313] Through the description of the above embodiments, it is clear to those skilled in the art that each embodiment can be implemented by means of software plus a general hardware platform, or of course by hardware. It is understood by those skilled in the art that all or part of the processes in the above embodiment methods can be implemented by instructing the relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM).

[0314] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Based on the idea of ​​the present application, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations in different aspects of the present application as above, which are not provided in detail for the sake of simplicity. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A modulation method for an inverter, characterized in that: The inverter adopts a space vector pulse width modulation mode, and the method includes: Obtaining the target voltage vector in each modulation cycle; When the target voltage vector is in the second overmodulation region of the inverter, a synthetic voltage vector is calculated according to the angle value of the target voltage vector and the modulation index; The inverter is controlled to output the synthetic voltage vector.

2. The method according to claim 1, characterized in that Before obtaining the target voltage vector in each modulation cycle, the method further includes: According to the modulation range of the target voltage vector, the modulation area of ​​the inverter is divided into a linear modulation area, an overmodulation area 1 and an overmodulation area 2; The modulation range is the range of the modulation index of the target voltage vector, and the modulation index is the ratio of the amplitude of the target voltage vector to the maximum phase voltage fundamental amplitude output by the inverter; The linear modulation area corresponds to the first modulation range, the overmodulation area 1 corresponds to the second modulation range, and the overmodulation area 2 corresponds to the third modulation range. The first modulation range is a modulation index ∈(0, first preset value], the second modulation range is a modulation index ∈(first preset value, second preset value], and the third modulation range is a modulation index ∈(second preset value, 1].

3. The method according to claim 1, characterized in that The method is applied to a controller, the controller including a first current regulator and a second current regulator, the target voltage vector being synthesized by a first voltage component and a second voltage component; The obtaining of the target voltage vector includes: Get the d-axis reference current and the q-axis reference current; Perform coordinate transformation on the three-phase current output by the inverter to obtain the actual d-axis current and q-axis current in the two-phase rotating coordinate system; calculating a first error signal between the d-axis reference current and the d-axis actual current, and a second error signal between the q-axis reference current and the q-axis actual current; Performing proportional control and integral control on the first error signal by the first current regulator to obtain a d-axis reference voltage in a two-phase rotating coordinate system; Performing proportional control and integral control on the second error signal by the second current regulator to obtain a q-axis reference voltage in a two-phase rotating coordinate system; Coordinate transformation is performed on the d-axis reference voltage and the q-axis reference voltage to obtain a first voltage component and a second voltage component in a two-phase stationary coordinate system.

4. The method according to claim 3, characterized in that Before calculating the synthetic voltage vector according to the angle value of the target voltage vector and the modulation coefficient, the method further includes: calculating a modulation index according to the target voltage vector; When the modulation index is greater than a second preset value, determining that the target voltage vector is in the second overmodulation region; The modulation index is calculated using the following formula: Among them, MI represents the modulation index, u α represents the first voltage component of the target voltage vector in the α-axis direction of the two-phase stationary coordinate system, u β The second voltage component of the target voltage vector in the β-axis direction of the two-phase stationary coordinate system, V dc Indicates the bus voltage value of the inverter.

5. The method according to claim 4, characterized in that Each working state of the inverter corresponds to a basic space vector, wherein the basic space vector includes a zero vector or a non-zero vector, and a plurality of non-zero vectors divide the space voltage vector plane into a plurality of sectors; The calculating of the synthetic voltage vector according to the angle value of the target voltage vector and the modulation index includes: determining a sector where a target voltage vector is located, and dividing the sector into two angular intervals; calculating an angle value of a target voltage vector, and determining an angle interval of the target voltage vector according to the angle value, wherein the angle interval is an interval consisting of a first angle and a second angle, and the first angle is smaller than the second angle; Calculating a first proportional coefficient according to the modulation degree; multiplying the first proportional coefficient by the second angle to obtain a third angle; When the angle value of the target voltage vector is greater than or equal to the first angle and the angle value of the target voltage vector is less than the third angle, calculating a synthetic voltage vector according to the first proportional coefficient, the basic space vector, and the target voltage vector; When the angle value of the target voltage vector is greater than or equal to the third angle and the angle value of the target voltage vector is less than the second angle, a second proportional coefficient is calculated based on the first proportional coefficient, and a synthetic voltage vector is calculated based on the first proportional coefficient, the second proportional coefficient, the basic space vector, and the target voltage vector.

6. The method according to claim 5, characterized in that The angle value of the target voltage vector is calculated using the following formula: Where θ represents the angle value of the target voltage vector, u β The second voltage component of the target voltage vector in the β-axis direction of the two-phase stationary coordinate system, u α represents the first voltage component of the target voltage vector in the α-axis direction of the two-phase stationary coordinate system; The first proportionality factor is calculated using the following formula: Wherein, P1 represents the first proportional coefficient, MI represents the modulation index, and a represents the second preset value.

7. The method according to claim 5, characterized in that The vector endpoints of multiple non-zero vectors are connected in sequence to form a regular hexagon; The calculating of a synthetic voltage vector according to the first proportional coefficient, the basic space vector, and the target voltage vector includes: Scaling the target voltage vector to the boundary of the regular hexagon to obtain a first vector, wherein the first vector has the same direction as the target voltage vector; determining an angle between the target voltage vector and each of the non-zero vectors, and taking the non-zero vector with the smallest angle as the second vector; A synthetic voltage vector is calculated according to the first vector, the second vector and the first proportional coefficient: The resultant voltage vector is calculated using the following formula: Vreal=(1-P1)*V1+P1*V2 Wherein, Vreal represents the resultant voltage vector, P1 represents the first proportional coefficient, V1 represents the first vector, and V2 represents the second vector.

8. The method according to claim 5, characterized in that The calculating the second proportional coefficient according to the first proportional coefficient includes: taking the difference between the second angle and the third angle as a first difference; taking the difference between the second angle and the angle value of the target voltage vector as a second difference; Calculating a second proportional coefficient according to the first proportional coefficient, the first difference, and the second difference; The second proportional coefficient is calculated using the following formula: Wherein, P2 represents the second proportional coefficient, θ1 represents the first difference, θ2 represents the second difference, and P1 represents the first proportional coefficient.

9. The method according to claim 5, characterized in that The vector endpoints of multiple non-zero vectors are connected in sequence to form a regular hexagon; The calculating of the synthetic voltage vector according to the first proportional coefficient, the second proportional coefficient, the basic space vector, and the target voltage vector includes: Scaling the target voltage vector to the boundary of the regular hexagon to obtain a first vector, wherein the first vector has the same direction as the target voltage vector; determining an angle between the target voltage vector and each of the non-zero vectors, and taking the non-zero vector with the smallest angle as the second vector; A synthetic voltage vector is calculated according to the first vector, the second vector, the first proportional coefficient, and the second proportional coefficient: The resultant voltage vector is calculated using the following formula: Vreal=(1-P2)*V1+P1*V2 Wherein, Vreal represents the resultant voltage vector, P2 represents the second proportional coefficient, V1 represents the first vector, P1 represents the first proportional coefficient, and V2 represents the second vector.

10. A controller, characterized in that: include: at least one processor, and a memory communicatively coupled to the at least one processor, wherein: The memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the method according to any one of claims 1 to 9.

11. A drive system, characterized in that: include: The controller according to claim 10; The inverter is connected to the controller and is used to convert direct current into alternating current according to a control signal sent by the controller.

12. A refrigerator compressor, characterized in that: include: The drive system according to claim 11; The motor is connected to the drive system and is used to convert alternating current into mechanical energy.

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