Single-resistance detection method, motor control method, controller, and control system

Abstract

The application discloses a single-resistance detection method, a motor control method, a controller and a control system. The method comprises the following steps: acquiring a DC bus current flowing through a single sampling resistor, and determining a conduction current of a lower tube of at least one phase bridge arm when the lower tube is turned on according to the DC bus current; acquiring a conduction tube voltage drop of the lower tube of the at least one phase bridge arm when the lower tube is turned on; determining a conduction resistance of the lower tube of the at least one phase bridge arm when the lower tube is turned on according to the conduction current and the conduction tube voltage drop of the lower tube of the at least one phase bridge arm when the lower tube is turned on; determining three-phase currents outside a current detection blind area according to the DC bus current, determining three-phase currents inside the current detection blind area according to the conduction tube voltage drop and the conduction resistance, and determining three-phase feedback currents of the motor according to the three-phase currents outside the blind area and the three-phase currents inside the blind area. The method can avoid the problems of motor noise increase caused by current detection in the blind area by PWM phase shift, and the problems of high current sampling cost and introduction of additional power consumption caused by using multiple resistors for current sampling.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese Patent Application No. 202111655481.6, filed on December 30, 2021, entitled "Single Resistance Detection Method, Motor Control Method, Controller and Control System", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to the field of motor control technology, and in particular to a single resistance detection method in a motor control system, a motor control method, a motor controller, a computer-readable storage medium, and a motor control system. Background Technology

[0004] In the fields of home appliance motor control and small, lightweight electric vehicle control, motor controllers often employ single-resistor current sampling to control the motor due to cost and space considerations, while switching devices are largely implemented using discrete components. However, when using a single resistor for current sampling, there is a current sampling blind zone (i.e., the unobserved area). A common solution is PWM (Pulse Width Modulation) phase shifting, but this leads to three-phase PWM asymmetry, introducing current harmonics and increasing motor noise, which is unacceptable for applications with high noise requirements. Using three or two resistors in the lower bridge arm for current sampling can effectively avoid the sampling blind zone and motor noise, but this increases the cost of current sampling and introduces additional power consumption. Summary of the Invention

[0005] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, the first objective of this invention is to propose a single-resistor detection method in a motor control system. This method obtains the three-phase current outside the dead zone by sampling with a single resistor, and obtains the three-phase current within the dead zone based on the voltage drop and on-resistance of the conducting tube when the lower tube is on. This effectively reconstructs the three-phase feedback current of the motor without requiring PWM phase shifting, effectively avoiding the increased motor noise caused by using PWM phase shifting for current detection in the dead zone. Furthermore, using a single resistor for current sampling avoids the high cost and additional power consumption associated with using multiple resistors for current sampling.

[0006] The second objective of this invention is to provide a motor control method.

[0007] The third objective of this invention is to propose another method for motor control.

[0008] The fourth objective of this invention is to provide a motor controller.

[0009] The fifth objective of this invention is to provide a computer-readable storage medium.

[0010] The sixth objective of this invention is to provide a motor control system.

[0011] To achieve the above objectives, a first aspect of the present invention provides a single-resistance detection method in a motor control system. The motor control system includes a three-phase inverter bridge for driving the motor and a single sampling resistor corresponding to the negative terminal of the DC bus. The method includes: acquiring the DC bus current flowing through the single sampling resistor, and determining the conduction current when the lower tube of at least one phase arm of the three-phase inverter bridge is turned on based on the DC bus current; acquiring the voltage drop across the conducting tube when the lower tube of at least one phase arm of the three-phase inverter bridge is turned on; determining the on-resistance when the lower tube of at least one phase arm of the three-phase inverter bridge is turned on based on the conduction current and the voltage drop across the conducting tube; determining the three-phase current outside the current detection blind zone based on the DC bus current, and determining the three-phase current within the current detection blind zone based on the voltage drop across the conducting tube and the on-resistance; and determining the three-phase feedback current of the motor based on the three-phase current outside the current detection blind zone and the three-phase current within the current detection blind zone.

[0012] According to the single-resistance detection method in the motor control system of the present invention, the DC bus current flowing through a single sampling resistor is obtained, and the three-phase current outside the current detection blind zone is determined based on the DC bus current; simultaneously, the conduction current when the lower tube of at least one phase arm of the three-phase inverter bridge is turned on is determined based on the DC bus current, and the conduction tube voltage drop when the lower tube of at least one phase arm of the three-phase inverter bridge is turned on is obtained, and the conduction resistance when the lower tube is turned on is determined based on the conduction current and the conduction tube voltage drop, and the three-phase current within the current detection blind zone is determined based on the conduction tube voltage drop and the conduction resistance; finally, the three-phase feedback current of the motor is determined based on the three-phase current outside the current detection blind zone and the three-phase current within the current detection blind zone. Therefore, by obtaining the three-phase current outside the dead zone based on single-resistor sampling, and obtaining the three-phase current inside the dead zone based on the on-tube voltage drop and on-resistance when the lower tube is turned on, the three-phase feedback current of the motor is effectively restored. Moreover, there is no need to perform PWM phase shifting, which effectively avoids the problem of increased motor noise caused by using PWM phase shifting for current detection in the dead zone. At the same time, using a single resistor for current sampling avoids the problems of high current sampling cost and additional power consumption caused by using multiple resistors for current sampling.

[0013] According to an embodiment of the present invention, before obtaining the DC bus current and the conduction tube voltage drop, the method further includes: determining a first sampling window time, a second sampling window time, and a third sampling window time, wherein the first sampling window time is the time from the underflow interruption moment of the PWM triangular wave to the time when the upper tube of any one phase arm of the three-phase inverter bridge is turned on; the second sampling window time is the time from the time when the upper tube of any one phase arm of the three-phase inverter bridge is turned on and delayed by a first preset time to the time when the upper tube of the next phase arm of the three-phase inverter bridge is turned on; and the third sampling window time is the time from the time when the upper tube of the next phase arm of the three-phase inverter bridge is turned on and delayed by a first preset time to the time when the upper tube of the last phase arm of the three-phase inverter bridge is turned on.

[0014] According to one embodiment of the present invention, determining the conduction current when the lower tube of at least one phase arm of the three-phase inverter bridge is turned on based on the DC bus current includes: sampling the DC bus current during a second sampling window time and a third sampling window time to obtain the phase current of the motor, and determining the conduction current when the lower tube of at least one phase arm of the three-phase inverter bridge is turned on based on the phase current of the motor.

[0015] According to one embodiment of the present invention, obtaining the conduction tube voltage drop when the lower tube of at least one phase arm of a three-phase inverter bridge is turned on includes: sampling the conduction tube voltage drop during at least one sampling window time, including a first sampling window time, a second sampling window time, and a third sampling window time, to obtain the conduction tube voltage drop when the lower tube of at least one phase arm of the three-phase inverter bridge is turned on.

[0016] According to one embodiment of the present invention, the conduction tube voltage drop includes the conduction tube voltage drop when the lower tube of two-phase bridge arm or three-phase bridge arm in a three-phase inverter bridge is turned on.

[0017] According to one embodiment of the present invention, the method further includes: obtaining the turn-off transistor voltage drop when the lower transistor of at least one phase arm of the three-phase inverter bridge is turned off; and determining the three-phase output line voltage and DC bus voltage of the motor based on the turn-off transistor voltage drop.

[0018] According to an embodiment of the present invention, before obtaining the voltage drop of the turn-off transistor, the method further includes: determining a second sampling window time, a third sampling window time, and a fourth sampling window time, wherein the second sampling window time is the time from when the upper transistor of any one phase arm of the three-phase inverter bridge is turned on and delayed by a first preset time to when the upper transistor of the next phase arm of the three-phase inverter bridge is turned on; the third sampling window time is the time from when the upper transistor of the next phase arm of the three-phase inverter bridge is turned on and delayed by a first preset time to when the upper transistor of the last phase arm of the three-phase inverter bridge is turned on; and the fourth sampling window time is the time from when the overflow interruption of the PWM triangular wave occurs to when the upper transistor of any one phase arm of the three-phase inverter bridge is turned off.

[0019] According to one embodiment of the present invention, obtaining the turn-off tube voltage drop when the lower tube of at least one phase arm of a three-phase inverter bridge is turned off includes: sampling the turn-off tube voltage drop during at least one of the second sampling window time, the third sampling window time, and the fourth sampling window time to obtain the turn-off tube voltage drop when the lower tube of at least one phase arm of the three-phase inverter bridge is turned off.

[0020] According to one embodiment of the present invention, the turn-off voltage drop includes the turn-off voltage drop when the lower tube of two-phase bridge arm or three-phase bridge arm in a three-phase inverter bridge is turned off.

[0021] To achieve the above objectives, a second aspect of the present invention provides a motor control method, comprising: executing the single-resistance detection method in the aforementioned motor control system to obtain the three-phase feedback current and three-phase output line voltage of the motor; performing coordinate transformation on the three-phase feedback current to obtain DC current and quadrature-axis current, and performing coordinate transformation on the three-phase output line voltage to obtain direct-axis voltage and quadrature-axis voltage; performing flux linkage and speed observation based on the DC current, quadrature-axis current, and direct-axis voltage and quadrature-axis voltage to obtain the rotor angle and rotor speed of the motor; and performing vector control on the motor based on the DC current, quadrature-axis current, rotor angle and rotor speed.

[0022] According to the motor control method of the present invention, based on the aforementioned single-resistor detection method, the three-phase current outside the blind zone is obtained by sampling with a single resistor, and the three-phase current inside the blind zone is obtained by the on-state voltage drop and on-resistance when the lower transistor is turned on. This effectively restores the three-phase feedback current of the motor, and eliminates the need for PWM phase shifting, thus effectively avoiding the problem of increased motor noise caused by using PWM phase shifting for current detection in the blind zone. At the same time, using a single resistor for current sampling avoids the problems of high current sampling cost and additional power consumption caused by using multiple resistors for current sampling. Furthermore, obtaining the three-phase output line voltage based on the off-state voltage drop of the lower transistor can effectively solve the problem of large errors between the actual voltage and the estimated voltage caused by the internal calculation of command voltage by the flux linkage and speed observer during vector control, which leads to low speed control accuracy and small control range, thus effectively improving the lower speed limit range and control accuracy of speed control.

[0023] To achieve the above objectives, a third aspect of the present invention proposes another motor control method, comprising: performing the single-resistance detection method in the aforementioned motor control system to obtain the three-phase feedback current of the motor; performing coordinate transformation on the three-phase feedback current to obtain DC current and quadrature-axis current; performing angle identification on the motor to obtain the rotor angle and rotor speed of the motor; and performing vector control on the motor based on the DC current and quadrature-axis current, as well as the rotor angle and rotor speed.

[0024] According to the motor control method of the present invention, based on the aforementioned single-resistor detection method, the three-phase current outside the dead zone is obtained by sampling with a single resistor, and the three-phase current inside the dead zone is obtained by the voltage drop and on-resistance of the conducting tube when the lower tube is turned on. This effectively restores the three-phase feedback current of the motor, and there is no need to perform PWM phase shifting. This effectively avoids the problem of increased motor noise caused by using PWM phase shifting for current detection in the dead zone. At the same time, using a single resistor for current sampling avoids the problems of high current sampling cost and additional power consumption caused by using multiple resistors for current sampling.

[0025] To achieve the above objectives, a fourth aspect of the present invention provides a motor controller, including a memory, a processor, and a single resistance detection program for a motor control system stored in the memory and executable on the processor. When the processor executes the single resistance detection program, it implements the aforementioned single resistance detection method for a motor control system.

[0026] According to the motor controller of the present invention, based on the aforementioned single-resistor detection method, the three-phase current outside the dead zone is obtained by sampling with a single resistor, and the three-phase current inside the dead zone is obtained by the voltage drop and on-resistance of the conducting tube when the lower tube is turned on. This effectively restores the three-phase feedback current of the motor, and there is no need to perform PWM phase shifting. This effectively avoids the problem of increased motor noise caused by using PWM phase shifting for current detection in the dead zone. At the same time, using a single resistor for current sampling avoids the problems of high current sampling cost and additional power consumption caused by using multiple resistors for current sampling.

[0027] To achieve the above objectives, a fifth aspect of the present invention provides a computer-readable storage medium storing a single resistance detection program for a motor control system, which, when executed by a processor, implements the aforementioned single resistance detection method for a motor control system.

[0028] According to the computer-readable storage medium of the present invention, based on the aforementioned single-resistor detection method, the three-phase current outside the dead zone is obtained by sampling with a single resistor, and the three-phase current inside the dead zone is obtained by the voltage drop and on-resistance of the conducting tube when the lower tube is turned on. This effectively restores the three-phase feedback current of the motor, and there is no need to perform PWM phase shifting. This effectively avoids the problem of increased motor noise caused by using PWM phase shifting for current detection in the dead zone. At the same time, using a single resistor for current sampling avoids the problems of high current sampling cost and additional power consumption caused by using multiple resistors for current sampling.

[0029] To achieve the above objectives, a sixth aspect of the present invention provides a motor control system, comprising: a three-phase inverter bridge connected between DC buses and driving a motor to operate; a current detection unit, including a single sampling resistor configured to detect the DC bus current; at least two voltage detection units configured to sample the conduction voltage drop when the lower transistor of at least two phase arms of the three-phase inverter bridge is turned on; and a control unit configured to determine the three-phase inverter bridge current based on the DC bus current. The control unit is configured to: obtain the conduction current when the lower tube of at least one phase arm of the three-phase inverter bridge is turned on; obtain the conduction voltage drop of the lower tube when the lower tube of at least one phase arm of the three-phase inverter bridge is turned on; determine the conduction resistance when the lower tube of at least one phase arm of the three-phase inverter bridge is turned on based on the conduction current and the conduction voltage drop; determine the three-phase current outside the current detection blind zone based on the DC bus current; and determine the three-phase current inside the current detection blind zone based on the conduction voltage drop and the conduction resistance. The control unit is also configured to determine the three-phase feedback current of the motor based on the three-phase current outside the current detection blind zone and the three-phase current inside the current detection blind zone.

[0030] According to the motor control system of the present invention, the DC bus current flowing through a single sampling resistor is acquired, and the three-phase current outside the current detection blind zone is determined based on the DC bus current. Simultaneously, the conduction current when the lower tube of at least one phase arm of the three-phase inverter bridge is turned on is determined based on the DC bus current, and the conduction tube voltage drop when the lower tube of at least one phase arm of the three-phase inverter bridge is turned on is acquired. The conduction resistance when the lower tube is turned on is determined based on the conduction current and the conduction tube voltage drop, and the three-phase current within the current detection blind zone is determined based on the conduction tube voltage drop and the conduction resistance. Finally, the three-phase feedback current of the motor is determined based on the three-phase current outside the current detection blind zone and the three-phase current within the current detection blind zone. Therefore, by obtaining the three-phase current outside the dead zone based on single-resistor sampling, and obtaining the three-phase current inside the dead zone based on the on-tube voltage drop and on-resistance when the lower tube is turned on, the three-phase feedback current of the motor is effectively restored. Moreover, there is no need to perform PWM phase shifting, which effectively avoids the problem of increased motor noise caused by using PWM phase shifting for current detection in the dead zone. At the same time, using a single resistor for current sampling avoids the problems of high current sampling cost and additional power consumption caused by using multiple resistors for current sampling.

[0031] According to one embodiment of the present invention, at least two voltage detection units are further configured to sample the voltage drop of the turn-off transistor when the lower transistor of at least one phase arm of the three-phase inverter bridge is turned off; the control unit is further configured to acquire the voltage drop of the turn-off transistor when the lower transistor of at least one phase arm of the three-phase inverter bridge is turned off, and determine the three-phase output line voltage and DC bus voltage of the motor based on the voltage drop of the turn-off transistor.

[0032] According to one embodiment of the present invention, at least two voltage detection units include two voltage detection units or three voltage detection units.

[0033] According to one embodiment of the present invention, the control unit is further configured to: perform coordinate transformation on the three-phase feedback current to obtain DC current and quadrature-axis current, and perform coordinate transformation on the three-phase output line voltage to obtain direct-axis voltage and quadrature-axis voltage; perform flux linkage and speed observation based on the DC current and quadrature-axis current, as well as the direct-axis voltage and quadrature-axis voltage, to obtain the rotor angle and rotor speed of the motor; and perform vector control on the motor based on the DC current and quadrature-axis current, as well as the rotor angle and rotor speed.

[0034] According to one embodiment of the present invention, the control unit is further configured to: perform coordinate transformation on the three-phase feedback current to obtain DC current and quadrature-axis current; perform angle identification on the motor to obtain the rotor angle and rotor speed of the motor; and perform vector control on the motor based on the DC current and quadrature-axis current, as well as the rotor angle and rotor speed.

[0035] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0036] Figure 1a This is a schematic diagram of the structure of a motor control system according to an embodiment of the present invention;

[0037] Figure 1b This is a schematic diagram of the structure of a motor control system according to another embodiment of the present invention;

[0038] Figure 2 This is a schematic flowchart of a single resistance detection method according to an embodiment of the present invention;

[0039] Figure 3 This is a sector diagram for space voltage vector control;

[0040] Figure 4a This is a schematic diagram of voltage and current sampling according to an embodiment of the present invention;

[0041] Figure 4b This is a schematic diagram of voltage and current sampling according to another embodiment of the present invention;

[0042] Figure 5 This is a schematic flowchart of a motor control method according to an embodiment of the present invention;

[0043] Figure 6 This is a topology diagram of motor vector control according to an embodiment of the present invention;

[0044] Figure 7This is a flowchart illustrating a motor control method according to another embodiment of the present invention;

[0045] Figure 8 This is a topology diagram of motor vector control according to another embodiment of the present invention;

[0046] Figure 9 This is a schematic diagram of the structure of a voltage detection unit according to an embodiment of the present invention. Detailed Implementation

[0047] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0048] In an embodiment of the present invention, the motor control system may include a three-phase inverter bridge and a single sampling resistor, wherein the three-phase inverter bridge is used to drive the motor to work, and the single sampling resistor is set to the negative terminal of the DC bus.

[0049] Specifically, refer to Figure 1a or Figure 1bAs shown, the three-phase inverter bridge includes a U-phase bridge arm, a V-phase bridge arm, and a W-phase bridge arm. The U-phase bridge arm includes an upper tube VT1 and a lower tube VT4; the V-phase bridge arm includes an upper tube VT3 and a lower tube VT6; and the W-phase bridge arm includes an upper tube VT5 and a lower tube VT2. The first end of the upper tube VT1 is connected to the positive terminal of the DC bus; the first end of the lower tube VT4 is connected to the second end of the upper tube VT1, and the second end of the lower tube VT4 is connected to the negative terminal of the DC bus; the first end of the upper tube VT3 is connected to the positive terminal of the DC bus; the first end of the lower tube VT6 is connected to the second end of the upper tube VT3, and the second end of the lower tube VT6 is connected to the negative terminal of the DC bus; the first end of the upper tube VT5 is connected to the positive terminal of the DC bus; the first end of the lower tube VT2 is connected to the second end of the upper tube VT5, and the second end of the lower tube VT2 is connected to the negative terminal of the DC bus; the control terminals of the upper tube VT1, lower tube VT4, upper tube VT3, lower tube VT6, upper tube VT5, and lower tube VT2 are respectively connected to the control unit. The control unit may include a microcontroller with memory, a DSP (Digital Signal Processing), or other control devices. This control unit controls the on / off state of six switching transistors to invert the DC power on the DC bus into AC power, supplying it to downstream loads such as motors to enable motor operation. The DC power source can be a battery or rectified AC power; there are no specific limitations. A DC bus capacitor is installed between the positive and negative terminals of the DC bus for energy storage and voltage regulation. A single-sampling resistor R is connected in series with the negative terminal of the DC bus for current sampling.

[0050] When using a single resistor for current sampling, a current sampling blind zone exists. A common solution is PWM phase shifting, but this leads to three-phase PWM asymmetry, introducing current harmonics and increasing motor noise, which is unacceptable for applications with high noise requirements. Using three or two resistors in the lower bridge arm for current sampling can effectively avoid the sampling blind zone and motor noise, but this increases current sampling cost and introduces additional power consumption. Therefore, this application provides a single-resistor detection method that can achieve current sampling within the blind zone without PWM phase shifting, avoiding the increased motor noise caused by PWM phase shifting for current detection in the blind zone. Furthermore, using a single resistor for current sampling avoids the high cost and additional power consumption associated with using multiple resistors.

[0051] Figure 2 This is a schematic flowchart of a single-resistance detection method according to an embodiment of the present invention. (Reference) Figure 2 As shown, the single resistance detection method may include the following steps:

[0052] Step S10: Obtain the DC bus current flowing through the single sampling resistor, and determine the conduction current when the lower tube of at least one phase arm of the three-phase inverter bridge is turned on based on the DC bus current.

[0053] It should be noted that the conduction current refers to the current flowing through the switching transistor when it is turned on, such as... Figure 1a As shown, the conduction current of the lower transistor VT4 is the current flowing through it when VT4 is turned on, the conduction current of the lower transistor VT6 is the current flowing through it when VT6 is turned on, and the conduction current of the lower transistor VT2 is the current flowing through it when VT2 is turned on. Since there is a correlation between the DC bus current and the conduction current of the lower transistors, the conduction currents of the lower transistors VT4, VT6, and VT2 can be obtained based on the DC bus current. For example, the conduction current of some of the lower transistors VT4, VT6, and VT2 can be directly obtained based on the loop current flow when they are turned on, while the conduction current of other transistors can be obtained based on the single-resistor current reconstruction method. Therefore, it is not necessary to set up a sampling resistor and current detection unit for each lower transistor, which helps to reduce cost and space occupation.

[0054] Step S20: Obtain the voltage drop of the conducting tube when the lower tube of at least one phase arm of the three-phase inverter bridge is turned on.

[0055] It should be noted that the conduction voltage drop refers to the voltage difference between the first and second terminals of the switching transistor when it is turned on. Figure 1a As shown, the conduction voltage drop of the lower transistor VT4 is the voltage difference between its first and second terminals when it is turned on; the conduction voltage drop of the lower transistor VT6 is the voltage difference between its first and second terminals when it is turned on; and the conduction voltage drop of the lower transistor VT2 is the voltage difference between its first and second terminals when it is turned on.

[0056] When obtaining the conduction voltage drop of the lower tube, a voltage detection unit can be set up for each lower tube. The voltage detection unit detects the conduction voltage drop of the corresponding lower tube, that is, the conduction voltage drop includes the conduction voltage drop when the lower tube of the three-phase bridge arm is conducting. For example Figure 1a As shown, a first voltage detection unit can be set for the lower transistor VT4 to detect the on-state voltage drop of the lower transistor VT4; a second voltage detection unit can be set for the lower transistor VT6 to detect the on-state voltage drop of the lower transistor VT6; and a third voltage detection unit can be set for the lower transistor VT2 to detect the on-state voltage drop of the lower transistor VT2.

[0057] When obtaining the conduction voltage drop of the lower tube, a voltage detection unit can be set up for each section of the lower tube. The voltage detection unit detects the conduction voltage drop of the corresponding lower tube, that is, the conduction voltage drop includes the conduction voltage drop when the lower tube of the two phase bridge arms is conducting. For example Figure 1bAs shown, a first voltage detection unit can be set for the lower transistor VT4 to detect the on-state voltage drop of VT4, and a second voltage detection unit can be set for the lower transistor VT6 to detect the on-state voltage drop of VT6; alternatively, a first voltage detection unit can be set for the lower transistor VT4 to detect the on-state voltage drop of VT4, and a third voltage detection unit can be set for the lower transistor VT2 to detect the on-state voltage drop of VT2 (this case is not shown); alternatively, a second voltage detection unit can be set for the lower transistor VT6 to detect the on-state voltage drop of VT6, and a third voltage detection unit can be set for the lower transistor VT2 to detect the on-state voltage drop of VT2 (this case is not shown).

[0058] Step S30: Determine the on-resistance of the lower tube of at least one phase arm of the three-phase inverter bridge when it is turned on based on the on-current and voltage drop of the lower tube.

[0059] Specifically, when the on-state voltage drop and on-state current of the switching transistor are obtained, a resistor can be calculated based on the relationship between voltage and current. This resistor is the on-state resistance of the switching transistor when it is turned on. For example... Figure 1a As shown, after obtaining the on-state voltage drop and on-state current of the lower transistor VT4, the on-state resistance of the lower transistor VT4 can be calculated; after obtaining the on-state voltage drop and on-state current of the lower transistor VT6, the on-state resistance of the lower transistor VT6 can be calculated; after obtaining the on-state voltage drop and on-state current of the lower transistor VT2, the on-state resistance of the lower transistor VT2 can be calculated. Specifically, these can be calculated using the following formula (1):

[0060]

[0061] Among them, R dson-real For the on-resistance, V ds(u,v,w)_on For the voltage drop of the conduction tube, I (u,v,w) To conduct current. It should be noted that in this application... (u,v,w) Indicates an or relationship.

[0062] like Figure 1b As shown, after obtaining the on-state voltage drop and on-state current of the lower transistor VT4, the on-state resistance of the lower transistor VT4 can be calculated; after obtaining the on-state voltage drop and on-state current of the lower transistor VT6, the on-state resistance of the lower transistor VT6 can be calculated.

[0063] Specifically, the results can be calculated using the following formula (2):

[0064]

[0065] Among them, R dson-real For the on-resistance, Vds(u,v)_on For the voltage drop of the conduction tube, I (u,v) To conduct current. It should be noted that in this application... (u,v) Indicates an or relationship.

[0066] Step S40: Determine the three-phase current outside the current detection blind zone based on the DC bus current, determine the three-phase current inside the current detection blind zone based on the voltage drop and on-resistance of the conducting tube, and determine the three-phase feedback current of the motor based on the three-phase current outside the current detection blind zone and the three-phase current inside the current detection blind zone.

[0067] It should be noted that, typically, when generating a PWM modulation wave, the output voltage is obtained by synthesizing two adjacent non-zero voltage vectors, such as... Figure 3 As shown, the output voltage Uo is synthesized from non-zero voltage vectors Uα and Uβ. When the output voltage Uo is near the boundary between adjacent sectors, the length of one of the non-zero voltage vectors will be very short, resulting in insufficient sampling time for the single-resistor current and thus causing a blind zone in current detection. Figure 3 As shown, the dark area is the current detection blind zone, while the light area has higher accuracy in current detection. Therefore, in this application, the three-phase current of the motor is obtained directly from the DC bus current outside the current detection blind zone, while the three-phase current of the motor is obtained from the conduction voltage drop of the lower tube in the blind zone and the conduction resistance of the lower tube determined in step S30 within the current detection blind zone. Then, the three-phase feedback current of the motor is obtained from the three-phase currents inside and outside the current detection blind zone.

[0068] When determining the three-phase current within the current detection dead zone, the on-state voltage drop of the lower tube within the current detection dead zone can be divided by the on-state resistance of the corresponding lower tube to obtain the three-phase current within the current detection dead zone.

[0069] As one implementation method, when each lower tube is equipped with a corresponding voltage detection unit, the conduction voltage drop of each lower tube in the current detection dead zone can be obtained through the voltage detection unit. Then, based on the conduction voltage drop of each lower tube and the corresponding conduction resistance of the lower tube, the three-phase current in the current detection dead zone can be calculated using the following formula (3):

[0070]

[0071] Among them, R dson-real For the on-resistance, V ds(u,v,w)_on For the voltage drop of the conduction tube, I' (u,v,w) For current detection of phase current within the dead zone.

[0072] For example, by dividing the on-state voltage drop of the lower transistor VT4 within the current detection blind zone by its corresponding on-resistance, the on-state current of VT4 within the current detection blind zone can be calculated. This current is the phase current of the bridge arm where VT4 is located, i.e., the U-phase current. Similarly, by dividing the on-state voltage drop of the lower transistor VT6 within the current detection blind zone by its corresponding on-resistance, the on-state current of VT6 within the current detection blind zone can be calculated. This current is the phase current of the bridge arm where VT6 is located, i.e., the V-phase current. Likewise, by dividing the on-state voltage drop of the lower transistor VT2 within the current detection blind zone by its corresponding on-resistance, the on-state current of VT2 within the current detection blind zone can be calculated. This current is the phase current of the bridge arm where VT2 is located, i.e., the W-phase current. Thus, the three-phase currents within the current detection blind zone can be obtained with high accuracy.

[0073] As another implementation method, when a voltage detection unit is set on a portion of the lower tube, the conduction tube voltage drop of the portion of the lower tube in the current detection blind zone can be obtained through the voltage detection unit. Then, based on the conduction tube voltage drop of the portion of the lower tube and the conduction resistance of the corresponding lower tube, the three-phase current in the current detection blind zone can be calculated by the following formulas (4)-(6).

[0074] For example, when voltage detection units are set for both lower transistors VT4 and VT6, the conduction current of lower transistor VT4 in the current detection blind zone can be calculated by dividing the conduction voltage drop of lower transistor VT4 in the current detection blind zone by the corresponding conduction resistance. This current is the phase current of the bridge arm where lower transistor VT4 is located, i.e., the U-phase current. The conduction current of lower transistor VT6 in the current detection blind zone can be calculated by dividing the conduction voltage drop of lower transistor VT6 in the current detection blind zone by the corresponding conduction resistance. This current is the phase current of the bridge arm where lower transistor VT6 is located, i.e., the V-phase current. Then, based on the fact that the sum of the three-phase currents is zero, the W-phase current is reconstructed, as shown in formula (4).

[0075]

[0076] Among them, R dson-real For the on-resistance, V ds(u,v)_on For the voltage drop of the conduction tube, I' (u,v) and I' w This is the phase current within the current detection dead zone. Therefore, the three-phase current within the current detection dead zone can be obtained, with lower hardware costs and higher accuracy.

[0077] For example, when voltage detection units are set for both lower transistors VT4 and VT2, the conduction current of lower transistor VT4 in the current detection blind zone can be calculated by dividing the conduction voltage drop of lower transistor VT4 in the current detection blind zone by the corresponding conduction resistance. This current is the phase current of the bridge arm where lower transistor VT4 is located, i.e., the U-phase current. The conduction current of lower transistor VT2 in the current detection blind zone can be calculated by dividing the conduction voltage drop of lower transistor VT2 in the current detection blind zone by the corresponding conduction resistance. This current is the phase current of the bridge arm where lower transistor VT2 is located, i.e., the W-phase current. Then, based on the fact that the sum of the three-phase currents is zero, the V-phase current is reconstructed from the U-phase current and the W-phase current, as shown in formula (5).

[0078]

[0079] Among them, R dson-real For the on-resistance, V ds(u,w)_on For the voltage drop of the conduction tube, I' (u,w) and I' v This is the phase current within the current detection dead zone. Therefore, the three-phase current within the current detection dead zone can be obtained, with lower hardware costs and higher accuracy.

[0080] For example, when voltage detection units are set for both lower transistors VT6 and VT2, the conduction current of lower transistor VT6 in the current detection blind zone can be calculated by dividing the conduction voltage drop of lower transistor VT6 in the current detection blind zone by the corresponding conduction resistance. This current is the phase current of the bridge arm where lower transistor VT6 is located, i.e., the V-phase current. The conduction current of lower transistor VT2 in the current detection blind zone can be calculated by dividing the conduction voltage drop of lower transistor VT2 in the current detection blind zone by the corresponding conduction resistance. This current is the phase current of the bridge arm where lower transistor VT2 is located, i.e., the W-phase current. Then, based on the fact that the sum of the three-phase currents is zero, the U-phase current is reconstructed, as shown in formula (6):

[0081]

[0082] Among them, R dson-real For the on-resistance, V ds(v,w)_on For the voltage drop of the conduction tube, I' (v,w) and I' u This is the phase current within the current detection dead zone. Therefore, the three-phase current within the current detection dead zone can be obtained, with lower hardware costs and higher accuracy.

[0083] In the above embodiments, by obtaining the three-phase current outside the dead zone based on single-resistor sampling, and obtaining the three-phase current within the dead zone based on the on-state voltage drop and on-resistance when the lower transistor is on, the three-phase feedback current of the motor is effectively restored. Furthermore, PWM phase shifting is unnecessary, effectively avoiding the increased motor noise caused by using PWM phase shifting for current detection within the dead zone. Simultaneously, using a single resistor for current sampling avoids the high cost and additional power consumption associated with using multiple resistors. Moreover, compared to the scheme of directly obtaining the three-phase current within the detection current dead zone based on the on-state voltage drop and standard on-resistance, the method... The on-resistance is an actual value, taking into account the influence of various factors such as temperature and current. Moreover, this on-resistance will not change abruptly in a short period of time, meaning the on-current will not change abruptly. Therefore, the obtained three-phase current in the dead zone has high accuracy, which is beneficial to the stability of the system. Furthermore, when using the on-tube voltage drop and on-resistance when all the lower tubes are on to obtain the three-phase current in the dead zone, it has high accuracy. When using the on-tube voltage drop and on-resistance when some of the lower tubes are on to obtain the three-phase current in the dead zone, it not only has high accuracy but also lower hardware costs, such as reducing the use of voltage detection units.

[0084] In some embodiments of the present invention, the single-resistance detection method further includes: obtaining the turn-off transistor voltage drop when the lower transistor of at least one phase arm of the three-phase inverter bridge is turned off; and determining the three-phase output line voltage and DC bus voltage of the motor based on the turn-off transistor voltage drop.

[0085] It should be noted that the turn-off voltage drop refers to the voltage difference between the first and second terminals of the switching transistor when the transistor is turned off. Figure 1a As shown, the turn-off voltage drop of the lower transistor VT4 is the voltage difference between its first and second terminals when it is turned off; the turn-off voltage drop of the lower transistor VT6 is the voltage difference between its first and second terminals when it is turned off; and the turn-off voltage drop of the lower transistor VT2 is the voltage difference between its first and second terminals when it is turned off.

[0086] When obtaining the voltage drop across the shut-off tube of the lower tube, it can be done through... Figure 1a The voltage detection unit corresponding to each lower transistor shown is used to detect the voltage drop across the turn-off transistor, which includes the voltage drop across the turn-off transistor when the lower transistor of each of the three phase arms of the three-phase inverter bridge is turned off; or, through... Figure 1b The voltage detection unit corresponding to the two lower transistors shown in the figure detects the voltage drop of the turn-off transistor, which includes the voltage drop of the turn-off transistor when the lower transistor of two phase arms in the three-phase inverter bridge is turned off. After obtaining the voltage drop of the turn-off transistor of the lower transistor, the three-phase output line voltage and DC bus voltage of the motor can be obtained based on the voltage drop of the turn-off transistor.

[0087] Specifically, the voltage drop across the turn-off transistor of the lower transistor of the three-phase inverter bridge is equal to the terminal voltage of the three phases at the negative terminal of the DC bus (with the negative terminal as reference point N), that is, the terminal voltage satisfies the following formula (7):

[0088]

[0089] Where Vun is the voltage at the U-phase terminal, Vvn is the voltage at the V-phase terminal, Vwn is the voltage at the W-phase terminal, Vdsu_off is the voltage drop across the turn-off transistor of the lower U-phase transistor, Vdsv_off is the voltage drop across the turn-off transistor of the lower V-phase transistor, and Vdsw_off is the voltage drop across the turn-off transistor of the lower W-phase transistor.

[0090] The three-phase output line voltage is:

[0091]

[0092] Where Vuv is the UV line voltage, Vvw is the VW line voltage, and Vwu is the WU line voltage.

[0093] The DC bus voltage is:

[0094] Vdc=Vdsu_off+Vds_upu=Vdsv_off+Vds_upv=Vdsw_off+Vds_upv (8)

[0095] Where Vdc is the DC bus voltage, Vds_upu is the on-circuit voltage drop of the upper tube of phase U, Vds_upv is the on-circuit voltage drop of the upper tube of phase V, and Vds_upw is the on-circuit voltage drop of the upper tube of phase W. Furthermore, Vdc is much larger than Vds_upu, Vds_upv, and Vds_upw, meaning the DC bus voltage is much larger than the on-circuit voltage drop of the upper tubes of each phase. Therefore, simplifying the above formula (8) yields the DC bus voltage as:

[0096] Vdc=Vdsu_off=Vdsv_off=Vdsw_off (9)

[0097] That is, the DC bus voltage is equal to the voltage drop of the turn-off transistor of each phase.

[0098] It should be noted that when there are only two turn-off transistor voltage drops, the third turn-off transistor voltage drop can be calculated based on the two turn-off transistor voltage drops, assuming that the sum of the voltages is zero. Thus, the three-phase output line voltage and DC bus voltage can be obtained while saving hardware costs.

[0099] Therefore, by obtaining the three-phase output line voltage based on the voltage drop across the turn-off transistor of the lower transistor, sensorless vector control can be performed. This effectively solves the problem of low speed accuracy and small control range in vector control when operating at low voltage and high current. This is due to the dead zone of the output voltage, transistor voltage drop, and line losses, which cause a large error between the command voltage and the actual voltage. Consequently, when using the command voltage as the input for the flux linkage and speed observer, this leads to a decline in control performance. This effectively improves the lower speed limit range and control accuracy of speed control. At the same time, the DC bus voltage can be obtained from the voltage drop across the turn-off transistor of the lower transistor. This allows for the acquisition of other key parameters that can improve vector control performance while achieving single-resistor current detection, without the need for separate output voltage detection units and DC bus voltage detection units, effectively reducing cost and space requirements.

[0100] In some embodiments of the present invention, the single-resistance detection method further includes: determining a first sampling window time, a second sampling window time, and a third sampling window time, wherein the first sampling window time is the time from the underflow interruption moment of the PWM triangular wave to the turn-on time of the upper transistor of any one phase arm of the three-phase inverter bridge; the second sampling window time is the time from the turn-on time of the upper transistor of any one phase arm of the three-phase inverter bridge after a first preset time delay to the turn-on time of the upper transistor of the next phase arm of the three-phase inverter bridge; and the third sampling window time is the time from the turn-on time of the upper transistor of the next phase arm of the three-phase inverter bridge after a first preset time delay to the turn-on time of the upper transistor of the last phase arm of the three-phase inverter bridge.

[0101] Furthermore, the single-resistance detection method also includes: determining the fourth sampling window time based on the conduction timing of the switching transistors in the three-phase inverter bridge, wherein the fourth sampling window time is the time from the overflow interruption moment of the PWM triangular wave to the turn-off time of the upper transistor of any phase arm in the three-phase inverter bridge.

[0102] It should be noted that the underflow interrupt time refers to the moment when the timer of the triangular wave is interrupted at the bottom of the triangular wave, that is, the moment when the triangular wave reaches its trough; the overflow interrupt time refers to the moment when the timer of the triangular wave is interrupted at the top of the triangular wave, that is, the moment when the triangular wave reaches its peak.

[0103] Specifically, refer to Figure 4aAs shown, corresponding to different PWM U, PWM V, and PWM W voltage vector moments, after avoiding current fluctuations caused by switching signal triggering, different acquisition signal moments appear. At the bottom of the triangular wave, the triangular wave timer will experience an underflow interrupt. At this time, PWM U, PWM V, and PWM W are all 0, the upper transistors VT1, VT3, and VT5 of the three-phase bridge arm are all off, and the lower transistors VT4, VT6, and VT2 of the three-phase bridge arm are all on. From this moment until any first turned-on upper transistor turns on (at... Figure 4a In the example shown, the time between the upper tube VT1 of the U-phase bridge arm (which is the first upper tube to be turned on, and Ta being the turn-on time of the upper tube VT1 of the U-phase bridge arm) and the time between these two points is the first sampling window time Ts1.

[0104] After the first sampling window time Ts1 ends, the turn-on voltage vector changes. After avoiding the current fluctuation caused by the switching signal trigger, a second sampling window time Ts2 appears. This second sampling window time Ts2 is from the turn-on of any first turned-on upper transistor (in... Figure 4a In the example shown, the upper tube VT1 of the U-phase bridge arm is the first upper tube to be turned on, and after a first preset time Tdelay, the conduction begins until the second upper tube is turned on (in...). Figure 4a In the example shown, the upper tube VT3 of the V-phase bridge arm is the second upper tube to be turned on, and Tb is the time when the upper tube VT3 of the V-phase bridge arm is turned on.

[0105] After the second sampling window time Ts2 ends, the turn-on voltage vector changes. After avoiding the current fluctuation caused by the switching signal trigger, a third sampling window time Ts3 occurs. This third sampling window time Ts3 is from the turn-on of the second turned-on upper transistor (in... Figure 4a In the example shown, the upper tube VT3 of the V-phase bridge arm is the second upper tube to be turned on, and the process begins after a first preset time Tdelay, until the last upper tube is turned on (in...). Figure 4a In the example shown, the upper tube VT5 of the W phase bridge arm is the last upper tube to be turned on, and Tc is the time when the upper tube VT5 of the W phase bridge arm is turned on.

[0106] After the third sampling window time Ts3 ends, at the triangular wave overflow interrupt time Tpwm, i.e., at the top of the triangular wave, the triangular wave timer experiences an overflow interrupt. At this time, PWM U, PWM V, and PWM W are all 1, the upper transistors VT1, VT3, and VT5 of the three-phase bridge arm are all turned on, and the lower transistors VT4, VT6, and VT2 of the three-phase bridge arm are all turned off. From this moment until the first turned-off upper transistor turns off (in... Figure 4a In the example shown, the time between the upper tube VT5 of the W phase bridge arm (which is the first upper tube to be turned off) and the time between the two is taken as the fourth sampling window time Ts4.

[0107] After determining the sampling window times Ts1, Ts2, Ts3, and Ts4, some or all of them can be used as the sampling times for the on-state voltage drop, off-state voltage drop, and current of the lower transistor. Figure 1a or Figure 1b The first voltage detection unit, the second voltage detection unit, and the third voltage detection unit shown, along with the current detection unit, sample the voltage and bus current, and finally obtain the on-state voltage drop, off-state voltage drop, and on-state current of some or all of the lower tubes.

[0108] In some embodiments of the present invention, determining the conduction current when the lower tube of at least one phase arm of the three-phase inverter bridge is turned on based on the DC bus current includes: sampling the DC bus current during the second sampling window time and the third sampling window time to obtain the phase current of the motor, and determining the conduction current when the lower tube of at least one phase arm of the three-phase inverter bridge is turned on based on the phase current of the motor.

[0109] Specifically, refer to Figure 4a As shown, outside the current detection blind zone, sampling window times Ts2 and Ts3 are sufficient to complete current sampling. Therefore, within the sampling window times Ts2 and Ts3, the current can be sampled using... Figure 1a or Figure 1b The current detection unit shown detects the DC bus current. Based on the DC bus current, two phase currents of the motor's three-phase current are reconstructed. The third phase current is calculated using single-resistor current reconstruction technology, specifically according to the formula Iu + Iv + Iw = 0, where Iu is the motor's U-phase current, Iv is the motor's V-phase current, and Iw is the motor's W-phase current. Furthermore, the conduction current of the lower transistor can be obtained based on the three-phase current, such as... Figure 1a or Figure 1b As shown, the on-state current of the lower transistor VT4 is Iu, the on-state current of the lower transistor VT6 is Iv, and the on-state current of the lower transistor VT2 is Iw. Therefore, outside the current detection blind zone, the three-phase current of the motor can be reconstructed based on single-resistor current detection. Simultaneously, the on-state current of each phase's lower transistor can be obtained. This on-state current can be used as a reference current to obtain the on-resistance of each phase's lower transistor. Furthermore, the three-phase current within the current detection blind zone can be reconstructed based on the on-resistance, without the need for PWM phase shifting.

[0110] In some embodiments of the present invention, obtaining the conduction tube voltage drop when the lower tube of at least one phase arm of the three-phase inverter bridge is turned on includes: sampling the conduction tube voltage drop during at least one of the first sampling window time, the second sampling window time, and the third sampling window time to obtain the conduction tube voltage drop when the lower tube of at least one phase arm of the three-phase inverter bridge is turned on.

[0111] In other words, some or all of the sampling window times Ts1, Ts2, and Ts3 can be used as the sampling time for the conduction voltage drop of the lower tube, and then... Figure 1a or Figure 1b The first voltage detection unit, the second voltage detection unit, and the third voltage detection unit shown can sample the voltage drop of the lower tube to obtain the voltage drop of the lower tube in part or all of its conduction.

[0112] In some embodiments of the present invention, obtaining the turn-off tube voltage drop when the lower tube of at least one phase arm of the three-phase inverter bridge is turned off includes: sampling the turn-off tube voltage drop during at least one of the second sampling window time, the third sampling window time, and the fourth sampling window time to obtain the turn-off tube voltage drop when the lower tube of at least one phase arm of the three-phase inverter bridge is turned off.

[0113] In other words, some or all of the sampling window times Ts2, Ts3, and Ts4 can be used as the sampling time for the voltage drop across the turn-off tube of the lower tube, and then... Figure 1a or Figure 1b The first voltage detection unit, the second voltage detection unit, and the third voltage detection unit shown in the figure can sample the voltage of the lower tube to obtain the voltage drop of the lower tube when it is partially or completely turned off.

[0114] Furthermore, as a first example, when each lower tube is equipped with a corresponding voltage detection unit, the conduction tube voltage drop of each phase bridge arm when the lower tube is turned on can be obtained within the first sampling window; within the second sampling window, the conduction tube voltage drop of the lower tube of the U-phase bridge arm, the conduction tube voltage drop of the lower tube of the W-phase bridge arm, and the turn-off tube voltage drop of the lower tube of the U-phase bridge arm can be obtained; within the third sampling window, the conduction tube voltage drop of the lower tube of the W-phase bridge arm, the turn-off tube voltage drop of the lower tube of the U-phase bridge arm, and the turn-off tube voltage drop of the lower tube of the V-phase bridge arm can be obtained, or the conduction tube voltage drop of the lower tube of the V-phase bridge arm, the turn-off tube voltage drop of the lower tube of the U-phase bridge arm, and the turn-off tube voltage drop of the lower tube of the W-phase bridge arm can be obtained; within the fourth sampling window, the turn-off tube voltage drop of each phase bridge arm when the lower tube is turned off can be obtained.

[0115] Specifically, refer to Figure 4a As shown, within the first sampling window time Ts1, since the lower tubes VT4, VT6 and VT2 of the three-phase bridge arm are all conducting, the conducting tube voltage drops of the lower tubes VT4, VT6 and VT2 can be collected simultaneously to obtain the conducting tube voltage drops Vdsu_on, Vdsv_on and Vdsw_on.

[0116] Within the second sampling window time Ts2, since the upper transistor of one phase of the three-phase bridge arm is in the conducting state and the lower transistors of the other two phases are in the conducting state, there is current in the DC bus. At this time, the phase current of the phase containing the upper transistor can be obtained by sampling the DC bus current Idc. At the same time, the turn-off voltage drop of the lower transistor of the phase containing the upper transistor and the conduction voltage drops of the lower transistors of the other two phases can be sampled. Figure 4a As shown, during the second sampling window time Ts2, the upper tube VT1 of the U-phase bridge arm is in the on state. Therefore, the U-phase current Iu can be obtained by sampling the DC bus current Idc. At the same time, the turn-off voltage drop Vdsu_off of the lower tube VT4, and the on-tube voltage drops Vdsv_on and Vdsw_on of the lower tubes VT6 and VT2 can be obtained by voltage sampling.

[0117] Within the third sampling window time Ts3, since the upper transistors of two phases of the three-phase bridge arm are in the conducting state, and the lower transistor of the other phase is in the conducting state, there is current in the DC bus. At this time, the phase current of the phase containing the lower transistor can be obtained by sampling the DC bus current Idc. At the same time, the conducting voltage drop of the lower transistor and the turning-off voltage drop of the lower transistor of the phase containing the upper transistor can be sampled. Figure 4a As shown, within the third sampling window time Ts3, the upper transistor VT1 of the U-phase bridge arm and the upper transistor VT3 of the V-phase bridge arm are both in the on state. Therefore, the W-phase current Iw can be obtained by sampling the DC bus current Idc. At the same time, the turn-off transistor voltage drops Vdsu_off and Vdsv_off of the lower transistors VT4 and VT6, as well as the on-transistor voltage drop Vdsw_on of the lower transistor VT2, can be obtained by voltage sampling. Alternatively, within the third sampling window time Ts3, the upper transistor VT1 of the U-phase bridge arm and the upper transistor VT5 of the W-phase bridge arm are both in the on state (not shown in the figure). Therefore, the V-phase current IV can be obtained by sampling the DC bus current Idc. At the same time, the turn-off transistor voltage drops Vdsu_off and Vdsw_off of the lower transistors VT4 and VT2, as well as the on-transistor voltage drop Vdsv_on of the lower transistor VT6, can be obtained by voltage sampling. That is, the second open tube may be phase V or phase W, and the corresponding phase current, the voltage drop of the open tube and the voltage drop of the closed tube are different when different phases are turned on.

[0118] Within the fourth sampling window time Ts4, since the upper tubes of all three phase bridge arms are in the on state and the lower tubes are in the off state, the off-state voltage drop of each lower tube can be sampled. That is, the off-state voltage drop Vdsu_off of lower tube VT4, the off-state voltage drop Vdsv_off of lower tube VT6, and the off-state voltage drop Vdsw_off of lower tube VT2 can be sampled.

[0119] It should be noted that when the sampling of the turn-off and turn-on voltage drops of the three lower transistors cannot be completed due to the short sampling window time Ts1 and the fourth sampling window time Ts4, the turn-off and turn-on voltage drops of the corresponding lower transistors can be sampled at other vector occurrence times according to the three-phase PWM turn-on relationship, i.e., vector state. For example, the turn-on voltage drop Vdsu_on of lower transistor VT4 can be obtained by sampling the voltage drop of lower transistor VT4 within the first sampling window time Ts1; the turn-on voltage drops Vdsv_on and Vdsw_on of lower transistors VT6 and VT2 can be obtained by sampling the voltage drop of lower transistors VT6 and VT2 within the second sampling window time Ts2; the turn-off voltage drops Vdsu_off and Vdsv_off of lower transistors VT4 and VT6 can be obtained by sampling the voltage drop of lower transistors VT4 and VT6 within the third sampling window time Ts3; and the turn-off voltage drop Vdsw_off of lower transistor VT2 can be obtained by sampling the voltage drop of lower transistor VT2 within the fourth sampling window time Ts4, thus obtaining the turn-on and turn-off voltage drops of each lower transistor.

[0120] When the U-phase current Iu and W-phase current Iw are obtained through the aforementioned method, the V-phase current Iv can be calculated based on the fact that the sum of the three-phase currents is zero. Similarly, when the U-phase current Iu and V-phase current Iv are obtained through the aforementioned method, the W-phase current Iw can be calculated based on the fact that the sum of the three-phase currents is zero. Thus, the three-phase currents Iu, Iv, and Iw of the motor outside the current detection blind zone can be obtained. At the same time, based on the three-phase currents, the conduction current of the lower tube VT4 can be obtained as Iu, the conduction current of the lower tube VT6 as Iv, and the conduction current of the lower tube VT2 as Iw.

[0121] Thus, by detecting voltage and current within different sampling window periods, the three-phase current of the motor can be reconstructed. At the same time, the conduction current, conduction voltage drop, and turn-off voltage drop of the lower tube of each phase bridge arm can be obtained. Based on the conduction current and conduction voltage drop, the conduction resistance of the lower tube can be calculated. Then, the three-phase current of the motor in the current detection blind zone can be obtained based on the conduction resistance. Finally, the three-phase feedback current of the motor can be obtained, and the three-phase output line voltage and DC bus voltage can be obtained based on the turn-off voltage drop.

[0122] As a second example, when each lower tube is equipped with a corresponding voltage detection unit, outside the current detection blind zone, the conduction tube voltage drop of each phase bridge arm when the lower tube is turned on can be obtained within the first sampling window time; within the second sampling window time, the conduction tube voltage drop of the lower tube of the V phase bridge arm, the conduction tube voltage drop of the lower tube of the W phase bridge arm, and the turn-off tube voltage drop of the lower tube of the V phase bridge arm can be obtained; within the third sampling window time, the conduction tube voltage drop of the lower tube of the U phase bridge arm, the turn-off tube voltage drop of the lower tube of the V phase bridge arm, and the turn-off tube voltage drop of the lower tube of the W phase bridge arm can be obtained, or the conduction tube voltage drop of the lower tube of the W phase bridge arm, the turn-off tube voltage drop of the lower tube of the U phase bridge arm, and the turn-off tube voltage drop of the lower tube of the V phase bridge arm can be obtained; within the fourth sampling window time, the turn-off tube voltage drop of each phase bridge arm when the lower tube is turned off can be obtained.

[0123] As a third example, when each lower tube is equipped with a corresponding voltage detection unit, outside the current detection blind zone, the conduction tube voltage drop of each phase bridge arm when the lower tube is turned on can be obtained within the first sampling window time; within the second sampling window time, the W-phase current, the conduction tube voltage drop of the lower tube of the U-phase bridge arm, the conduction tube voltage drop of the lower tube of the V-phase bridge arm, and the turn-off tube voltage drop of the lower tube of the W-phase bridge arm can be obtained; within the third sampling window time, the U-phase current, the conduction tube voltage drop of the lower tube of the U-phase bridge arm, the turn-off tube voltage drop of the lower tube of the V-phase bridge arm, and the turn-off tube voltage drop of the lower tube of the W-phase bridge arm can be obtained, or the V-phase current, the conduction tube voltage drop of the lower tube of the V-phase bridge arm, the turn-off tube voltage drop of the lower tube of the U-phase bridge arm, and the turn-off tube voltage drop of the lower tube of the W-phase bridge arm can be obtained; within the fourth sampling window time, the turn-off tube voltage drop of each phase bridge arm when the lower tube is turned off can be obtained.

[0124] It should be noted that the second example involves sampling the phase current, the on-state voltage drop of the lower transistor, and the off-state voltage drop when the first switched-on upper transistor is phase V and the last switched-on upper transistor is phase U or W. The third example involves sampling the phase current, the on-state voltage drop of the lower transistor, and the off-state voltage drop when the first switched-on upper transistor is phase W and the last switched-on upper transistor is phase U or V. The sampling principle is the same as... Figure 4a The example shown is similar; please refer to the specific examples. Figure 4a As shown, this will not be elaborated further here. Table 1 presents the relationship between the phase current corresponding to the DC bus current in different sectors, and the sampling of the on-state voltage drop and off-state voltage drop of the lower transistor:

[0125] Table 1

[0126]

[0127] In Table 1, UH represents the conduction status of the upper tube of the U-phase bridge arm, VH represents the conduction status of the upper tube of the V-phase bridge arm, and WH represents the conduction status of the upper tube of the W-phase bridge arm. "1" indicates conduction, and "0" indicates disconnection. Idc is the DC bus current, Iu is the U-phase current, Iv is the V-phase current, Iw is the W-phase current, Vdsu_on is the conduction voltage drop of the lower tube of the U-phase bridge arm, Vdsv_on is the conduction voltage drop of the lower tube of the V-phase bridge arm, Vdsw_on is the conduction voltage drop of the lower tube of the W-phase bridge arm, Vdsu_off is the shutdown voltage drop of the lower tube of the U-phase bridge arm, Vdsv_off is the shutdown voltage drop of the lower tube of the V-phase bridge arm, and Vdsw_off is the shutdown voltage drop of the lower tube of the W-phase bridge arm.

[0128] It should be noted that in the above example, outside the current detection blind zone, since the sampling window times Ts2 and Ts3 are sufficient to complete the current sampling, the three-phase current of the motor can be reconstructed based on the two-phase currents of the detected three-phase current. Within the current detection blind zone, the sampling window time Ts2 or Ts3 is too short to complete current sampling, thus preventing the detection of two phases of the three-phase current and consequently making it impossible to reconstruct the motor's three-phase current. In this case, the conduction current of each phase's lower transistor can be obtained based on the three-phase current outside the current detection blind zone, and the on-resistance can be calculated based on the on-resistance voltage drop of the lower transistors outside the current detection blind zone. Then, within the current detection blind zone, instead of current sampling, the on-resistance voltage drop of at least two phases' lower transistors is sampled. Based on the on-resistance voltage drop and the calculated on-resistance, the conduction current of at least two phases within the current detection blind zone is calculated, thereby obtaining the motor's three-phase current (when only two phases are calculated, the third phase can be calculated based on the sum of the currents being zero). This achieves the acquisition of the three-phase current within the current detection blind zone. The three-phase output line voltage and DC bus voltage can be measured both outside and inside the current detection blind zone.

[0129] To facilitate understanding, the following specific example illustrates the process of obtaining the three-phase feedback current, three-phase output line voltage, and DC bus voltage of a motor.

[0130] Specifically, with Figure 4aTaking the example shown, four sampling window times Ts1, Ts2, Ts3 and Ts4 are first calculated based on the conduction timing. Ts1 = Ta - T, where Ta is the conduction time of the upper tube VT1 of the U-phase bridge arm. Since the sampling window time is timed by another timer (whose counting pulse can be at the same frequency as the PWM pulse), the initial time T = 0, so Ts1 = Ta; Ts2 = Tb - Ta - Tdelay, where Tb is the conduction time of the upper tube VT3 of the V-phase bridge arm, and Tdelay is the first preset time; Ts3 = Tc - Tb - Tdelay, where Tc is the conduction time of the upper tube VT5 of the W-phase bridge arm; Ts4 = Tc' - T, where Tc' is the turn-off time of the upper tube VT5 of the W-phase bridge arm. The initial time T = 0, so Ts4 = Tc'.

[0131] Then, the sampling window times Ts2 and Ts3 are judged. If both sampling window times Ts2 and Ts3 are greater than or equal to the minimum current sampling time tmin, it indicates that the current sampling window is in progress. Figure 3 Outside the current detection blind zone shown, if at least one of the sampling window times Ts2 and Ts3 is less than the minimum current sampling time tmin, it indicates that the current is currently in... Figure 3 The current detection blind zone is shown. It should be noted that the determination of whether a device is within the current detection blind zone can also be based on the lengths of two adjacent non-zero voltage vectors.

[0132] Assuming in Figure 4aDuring the first carrier cycle, the current is outside the current detection blind zone. Current sampling is then performed, and the three-phase current of the motor is reconstructed based on the sampling results. Simultaneously, the three-phase output line voltage and DC bus voltage are acquired. Specifically, when the triangular wave timer experiences an underflow interrupt (i.e., the PWM underflow interrupt begins), the first sampling window time Ts1 is entered. At this time, the sampling timer's timing is set to Ta+Tdelay, and the sampling timer is started. Simultaneously, sampling of the on-state voltage drop of the lower transistors begins. This involves sampling the on-state voltage drop of one or more lower transistors, such as sampling the on-state voltage drops of lower transistors VT4, VT6, and VT2 to obtain the on-state voltage drops Vdsu_on, Vdsv_on, and Vdsw_on, which are then saved. When the sampling timer reaches Ta+Tdelay, it enters the second sampling window time Ts2. At this time, the sampling timer is set to Ts2+Tdelay and the sampling timer is started. Simultaneously, the sampling of the on-state voltage drop of the lower transistors VT6 and VT2, the off-state voltage drop of the lower transistor VT4, and the DC bus current Idc are obtained. The on-state voltage drops Vdsv_on and Vdsw_on of the lower transistors VT6 and VT2, the off-state voltage drop Vdsu_off of the lower transistor VT4, and the U-phase current Iu are obtained and saved. When the sampling timer reaches Ts2 + Tdelay, the third sampling window Ts3 begins. At this time, sampling begins for the on-state voltage drop of the lower transistor VT2, the off-state voltage drops of the lower transistors VT4 and VT6, and the DC bus current Idc. This yields the on-state voltage drop Vdsw_on of VT2, the off-state voltage drops Vdsu_off and Vdsv_off of VT4 and VT6, and the W-phase current Iw, which are then saved. When an overflow interrupt occurs in the triangular wave timer (i.e., the PWM overflow interrupt begins), the fourth sampling window Ts4 begins. Sampling begins for the off-state voltage drops of the lower transistors, sampling the off-state voltage drops of one or more lower transistors. For example, sampling the off-state voltage drops of lower transistors VT4, VT6, and VT2 yields the off-state voltage drops Vdsu_off, Vdsv_off, and Vdsw_off, which are then saved. This completes the sampling for one carrier cycle.

[0133] Then, the V-phase current Iv can be calculated according to Iu+Iv+Iw=0, thereby obtaining the three-phase currents Iu, Iv and Iw of the motor outside the current detection blind zone. Based on the relationship between the three-phase current of the motor and the conduction current of the lower tube, the conduction current of the lower tube can be obtained, that is, the conduction current of the lower tube is Iu, Iv and Iw. Then, according to the conduction current of the lower tube and the conduction tube voltage drop Vdsu_on, Vdsv_on and Vdsw_on of the lower tube, the conduction resistance of each lower tube is calculated by the aforementioned formula (1) and saved. At the same time, according to the turn-off tube voltage drop Vdsu_off, Vdsv_off and Vdsw_off of the lower tube, the three-phase output line voltage Vuv, Vvw and Vwu of the motor and the DC bus voltage Vdc are obtained by the aforementioned formulas (8) and (9) and saved.

[0134] Next, the next carrier cycle begins. Assuming the next carrier cycle falls within the current detection blind zone, current sampling is not performed at this time. Instead, the three-phase current of the motor within the current detection blind zone is obtained based on the previously acquired on-resistance of the lower transistors of each phase. Simultaneously, the three-phase output line voltage and DC bus voltage are also acquired. Specifically, when the triangular wave timer experiences an underflow interrupt (i.e., the PWM underflow interrupt begins), the first sampling window time Ts1 is entered. At this time, the timing of the sampling timer is set to Ta+Tdelay, and the sampling timer is started. Simultaneously, sampling of the on-state voltage drop of the lower transistors begins, sampling the on-state voltage drop of one or more lower transistors. For example, sampling the on-state voltage drop of lower transistor VT4 yields the on-state voltage drop Vdsu_on (assuming the first sampling window time Ts1 is short, only one can be sampled), and this data is saved. When the sampling timer reaches Ta+Tdelay, the second sampling window time Ts2 begins. At this time, the sampling timer's timing is set to Ts2+Tdelay, and the sampling timer starts. Simultaneously, sampling begins for the on-state voltage drop of the lower transistors VT6 and VT2, as well as the off-state voltage drop of the lower transistor VT4. The on-state voltage drops Vdsv_on and Vdsw_on of VT6 and VT2, and the off-state voltage drop Vdsu_off of VT4 are obtained (assuming the second sampling window time Ts2 is long), and saved. When the sampling timer reaches Ts2+Tdelay, the third sampling window time Ts3 begins. Since the third sampling window time Ts3 is short (assuming it is less than the minimum current sampling time tmin), no sampling occurs at this time. When an overflow interrupt occurs in the triangular wave timer (i.e., the PWM overflow interrupt begins), the fourth sampling window time Ts4 begins. Sampling of the turn-off transistor voltage drops of one or more lower transistors is then performed. For example, the turn-off transistor voltage drops of lower transistors VT4, VT6, and VT2 are sampled to obtain the turn-off transistor voltage drops Vdsu_off, Vdsv_off, and Vdsw_off (assuming the fourth sampling window time Ts4 is long), and these values ​​are saved. This completes all sampling for one carrier cycle.

[0135] Then, based on the on-state voltage drops Vdsu_on, Vdsv_on, and Vdsw_on of the lower transistor and the on-state resistance of the corresponding lower transistor calculated at the end of the first carrier cycle, the on-state current of the lower transistor, i.e., the three-phase currents Iu', Iv', and Iw' of the motor, are calculated using the aforementioned formula (3). It should be noted that the ratio between the standard on-state resistance of the switching transistor and the calculated on-state resistance can also be calculated at the end of the first carrier cycle. Then, at the end of the carrier cycle, the initial three-phase current is first calculated based on the on-state voltage drops Vdsu_on, Vdsv_on, and Vdsw_on of the lower transistor and the standard on-state resistance. Then, the initial three-phase current is corrected using the ratio to obtain the three-phase currents Iu', Iv', and Iw' of the motor. Meanwhile, the three-phase output line voltages Vuv, Vvw, and Vwu of the motor and the DC bus voltage Vdc are obtained and saved using the above formulas (8) and (9) based on the voltage drops of the turn-off tubes Vdsu_off, Vdsv_off, and Vdsw_off.

[0136] Next, in the next carrier cycle, the aforementioned process is repeated. The three-phase currents Iu, Iv, and Iw outside the current detection blind zone and the three-phase currents Iu', Iv', and Iw' inside the current detection blind zone are combined to obtain the complete three-phase current as the three-phase feedback current of the motor and saved so that the motor can be controlled based on the three-phase feedback current, such as performing FOC (Field Oriented Control, also known as Voltage Vector Control) current loop control. At the same time, the motor is controlled based on the three-phase output line voltages Vuv, Vvw, and Vwu and the DC bus voltage Vdc. For example, the flux linkage observer is estimated using the three-phase output line voltages Vuv, Vvw, and Vwu, and the voltage vector width and conduction time of the PWM are calculated using the DC bus voltage Vdc when the output voltage is passed through SVPWM (Space Vector Pulse Width Modulation).

[0137] In the above embodiments, the deviation problem of current detection and restoration caused by temperature changes in the switching transistor due to temperature changes is corrected by the time-division current sampling technology. It also realizes the detection of multiple input voltage variables in the FOC calculation process. On the one hand, it avoids the harmonics and motor noise of the current sampled by a single resistor. On the other hand, it reduces the voltage sampling circuit, realizes multiple uses, and has high engineering application value.

[0138] It should be noted that, in order to provide comprehensive protection for each switching transistor, in the aforementioned example, a corresponding voltage sampling unit is set for each lower transistor. The voltage sampling unit samples the voltage drop of the lower transistor. However, the sampling method is not limited to sampling the voltage drop of all lower transistors. It is also possible to sample the voltage drop of one or two lower transistors and deduce all the results based on the principle of symmetry, so as to reduce costs.

[0139] As a first example, when the lower tubes VT4 and VT6 are equipped with corresponding voltage detection units, the conduction tube voltage drops of the lower tubes of the U-phase and V-phase bridge arms when they are turned on can be obtained within the first sampling window; within the second sampling window, the U-phase current, the conduction tube voltage drop of the lower tube of the V-phase bridge arm, and the turn-off tube voltage drop of the lower tube of the U-phase bridge arm can be obtained; within the third sampling window, the W-phase current, the turn-off tube voltage drop of the lower tube of the U-phase bridge arm, and the turn-off tube voltage drop of the lower tube of the V-phase bridge arm, or the V-phase current, the conduction tube voltage drop of the lower tube of the V-phase bridge arm, and the turn-off tube voltage drop of the lower tube of the U-phase bridge arm can be obtained; within the fourth sampling window, the turn-off tube voltage drops of the lower tubes of the U-phase and V-phase bridge arms when they are turned off can be obtained.

[0140] Specifically, refer to Figure 4b As shown, within the first sampling window time Ts1, since the lower tubes VT4, VT6 and VT2 of the three-phase bridge arm are all conducting, the conducting tube voltage drop of the lower tubes VT4 and VT6 can be collected to obtain the conducting tube voltage drops Vdsu_on and Vdsv_on.

[0141] Within the second sampling window time Ts2, since the upper transistor of one phase of the three-phase bridge arm is in the conducting state and the lower transistors of the other two phases are in the conducting state, there is current in the DC bus. At this time, the phase current of the phase containing the upper transistor can be obtained by sampling the DC bus current Idc. At the same time, the turn-off voltage drop of the lower transistor of the phase containing the upper transistor and the conduction voltage drops of the lower transistors of the other two phases can be sampled. Figure 4b As shown, during the second sampling window time Ts2, the upper tube VT1 of the U-phase bridge arm is in the on state. Therefore, the U-phase current Iu can be obtained by sampling the DC bus current Idc. At the same time, the voltage drop Vdsu_off of the turn-off tube VT4 and the voltage drop Vdsv_on of the turn-on tube VT6 can be obtained by voltage sampling.

[0142] Within the third sampling window time Ts3, since the upper transistors of two phases of the three-phase bridge arm are in the conducting state, and the lower transistor of the other phase is in the conducting state, there is current in the DC bus. At this time, the phase current of the phase containing the lower transistor can be obtained by sampling the DC bus current Idc. At the same time, the conducting voltage drop of the lower transistor and the turning-off voltage drop of the lower transistor of the phase containing the upper transistor can be sampled. Figure 4bAs shown, within the third sampling window time Ts3, both the upper transistor VT1 of the U-phase bridge arm and the upper transistor VT3 of the V-phase bridge arm are in the on state. Therefore, the W-phase current Iw can be obtained by sampling the DC bus current Idc, and the turn-off voltage drops Vdsu_off and Vdsv_off of the lower transistors VT4 and VT6 can be obtained by voltage sampling. Alternatively, within the third sampling window time Ts3, both the upper transistor VT1 of the U-phase bridge arm and the upper transistor VT5 of the W-phase bridge arm are in the on state (not shown in the figure). Therefore, the V-phase current IV can be obtained by sampling the DC bus current Idc, and the turn-off voltage drop Vdsu_off of the lower transistor VT4 and the on-state voltage drop Vdsv_on of the lower transistor VT6 can be obtained by voltage sampling. That is, the second transistor to be turned on may be either the V-phase or the W-phase, and the corresponding phase current, on-state voltage drop, and turn-off voltage drop are different when different phases are turned on.

[0143] Within the fourth sampling window time Ts4, since the upper tubes of the three-phase bridge arms are all in the on state and the lower tubes are all in the off state, the off-tube voltage drop Vdsu_off of the lower tube VT4 and the off-tube voltage drop Vdsv_off of the lower tube VT6 can be sampled.

[0144] It should be noted that when the sampling of the turn-off and turn-on voltage drops of the two lower transistors cannot be completed due to the short first sampling window time Ts1 and the fourth sampling window time Ts4, the turn-off and turn-on voltage drops of the corresponding lower transistors can be sampled at other vector occurrence times according to the three-phase PWM turn-on relationship, i.e., vector state. For example, the turn-on voltage drop Vdsu_on of the lower transistor VT4 can be obtained by sampling the voltage drop of the lower transistor VT4 within the first sampling window time Ts1, the turn-on voltage drop Vdsv_on of the lower transistor VT6 can be obtained by sampling the voltage drop of the lower transistor VT6 within the second sampling window time Ts2, and the turn-off voltage drops Vdsu_off and Vdsv_off of the lower transistors VT4 and VT6 can be obtained by sampling the voltage drops of the lower transistors VT4 and VT6 within the third sampling window time Ts3, thereby obtaining the turn-on and turn-off voltage drops of the two lower transistors.

[0145] When the U-phase current Iu and W-phase current Iw are obtained through the aforementioned method, the V-phase current Iv can be calculated based on the fact that the sum of the three-phase currents is zero. Similarly, when the U-phase current Iu and V-phase current Iv are obtained through the aforementioned method, the W-phase current Iw can be calculated based on the fact that the sum of the three-phase currents is zero. Thus, the three-phase currents Iu, Iv, and Iw of the motor outside the current detection blind zone can be obtained. At the same time, based on the three-phase currents, the conduction current of the lower tube VT4, Iu, and the conduction current of the lower tube VT6, Iv, can be obtained.

[0146] Thus, within different sampling window times, the three-phase current of the motor can be reconstructed by detecting voltage and current. At the same time, the conduction current, conduction voltage drop, and turn-off voltage drop of the lower tube of the two-phase bridge arm can be obtained. Based on the conduction current and conduction voltage drop, the conduction resistance of the lower tube can be calculated. Then, the three-phase current of the motor in the current detection blind zone can be obtained based on the conduction resistance. Finally, the three-phase feedback current of the motor can be obtained, and the three-phase output line voltage and DC bus voltage can be obtained based on the turn-off voltage drop.

[0147] As a second example, when the lower transistors VT4 and VT6 are equipped with corresponding voltage detection units, outside the current detection blind zone, the conduction voltage drop of the lower transistors of the U-phase and V-phase bridge arms when they are turned on can be obtained within the first sampling window time; within the second sampling window time, the V-phase current, the conduction voltage drop of the lower transistor of the U-phase bridge arm, and the turn-off voltage drop of the lower transistor of the V-phase bridge arm can be obtained; within the third sampling window time, the U-phase current, the conduction voltage drop of the lower transistor of the U-phase bridge arm, and the turn-off voltage drop of the lower transistor of the V-phase bridge arm can be obtained, or the W-phase current, the turn-off voltage drop of the lower transistor of the U-phase bridge arm, and the turn-off voltage drop of the lower transistor of the V-phase bridge arm can be obtained; within the fourth sampling window time, the turn-off voltage drop of the lower transistors of the U-phase and V-phase bridge arms when they are turned off can be obtained.

[0148] As a third example, when the lower transistors VT4 and VT6 are equipped with corresponding voltage detection units, outside the current detection blind zone, the conduction voltage drop of the lower transistors of the U-phase and V-phase bridge arms when they are turned on can be obtained within the first sampling window time; within the second sampling window time, the W-phase current, the conduction voltage drop of the lower transistor of the U-phase bridge arm, and the conduction voltage drop of the lower transistor of the V-phase bridge arm can be obtained; within the third sampling window time, the U-phase current, the conduction voltage drop of the lower transistor of the U-phase bridge arm, and the turn-off voltage drop of the lower transistor of the V-phase bridge arm can be obtained, or the V-phase current, the conduction voltage drop of the lower transistor of the V-phase bridge arm, and the turn-off voltage drop of the lower transistor of the U-phase bridge arm can be obtained; within the fourth sampling window time, the turn-off voltage drop of the lower transistors of the U-phase and V-phase bridge arms when they are turned off can be obtained.

[0149] It should be noted that the second example involves sampling the phase current, the on-state voltage drop of the lower transistor, and the off-state voltage drop when the first switched-on upper transistor is phase V and the last switched-on upper transistor is phase U or W. The third example involves sampling the phase current, the on-state voltage drop of the lower transistor, and the off-state voltage drop when the first switched-on upper transistor is phase W and the last switched-on upper transistor is phase U or V. The sampling principle is the same as... Figure 4b The example shown is similar; please refer to the specific examples. Figure 4b As shown, I will not go into details here.

[0150] It should be noted that in the above example, outside the current detection blind zone, since the sampling window times Ts2 and Ts3 are sufficient to complete the current sampling, the three-phase current of the motor can be reconstructed based on the two-phase currents of the detected three-phase current. Within the current detection blind zone, the sampling window time Ts2 or Ts3 is too short to complete current sampling, thus preventing the detection of two phases of the three-phase current and consequently making it impossible to reconstruct the motor's three-phase current. In this case, the conduction current of the lower transistors of the two phases outside the current detection blind zone can be obtained, and the on-resistance can be calculated based on the on-resistance voltage drop of the lower transistors outside the current detection blind zone. Then, within the current detection blind zone, instead of current sampling, the on-resistance voltage drop of the lower transistors of the two phases is sampled. Based on the on-resistance voltage drop and the calculated on-resistance, the conduction current of the lower transistors of the two phases within the current detection blind zone can be calculated. The third phase can be calculated based on the fact that the sum of the currents is zero, thus obtaining the motor's three-phase current. This achieves the acquisition of the three-phase current within the current detection blind zone. The three-phase output line voltage and DC bus voltage can be measured both outside and inside the current detection blind zone.

[0151] To facilitate understanding, the following specific example illustrates the process of obtaining the three-phase feedback current, three-phase output line voltage, and DC bus voltage of a motor.

[0152] Specifically, with Figure 4b Taking the example shown, four sampling window times Ts1, Ts2, Ts3 and Ts4 are first calculated based on the conduction timing. Ts1 = Ta - T, where Ta is the conduction time of the upper tube VT1 of the U-phase bridge arm. Since the sampling window time is timed by another timer (whose counting pulse can be at the same frequency as the PWM pulse), the initial time T = 0, so Ts1 = Ta; Ts2 = Tb - Ta - Tdelay, where Tb is the conduction time of the upper tube VT3 of the V-phase bridge arm, and Tdelay is the first preset time; Ts3 = Tc - Tb - Tdelay, where Tc is the conduction time of the upper tube VT5 of the W-phase bridge arm; Ts4 = Tc' - T, where Tc' is the turn-off time of the upper tube VT5 of the W-phase bridge arm. The initial time T = 0, so Ts4 = Tc'.

[0153] Then, the sampling window times Ts2 and Ts3 are judged. If both sampling window times Ts2 and Ts3 are greater than or equal to the minimum current sampling time tmin, it indicates that the current sampling window is in progress. Figure 3 Outside the current detection blind zone shown, if at least one of the sampling window times Ts2 and Ts3 is less than the minimum current sampling time tmin, it indicates that the current is currently in... Figure 3 The current detection blind zone is shown. It should be noted that the determination of whether a device is within the current detection blind zone can also be based on the lengths of two adjacent non-zero voltage vectors.

[0154] Assuming in Figure 4b During the first carrier cycle, the current is outside the current detection blind zone. Current sampling is then performed, and the three-phase current of the motor is reconstructed based on the sampling results. Simultaneously, the three-phase output line voltage and DC bus voltage are acquired. Specifically, when the triangular wave timer experiences an underflow interrupt (i.e., the PWM underflow interrupt begins), the first sampling window time Ts1 is entered. At this time, the sampling timer's timing is set to Ta+Tdelay, and the sampling timer is started. Simultaneously, sampling of the on-state voltage drop of the lower transistors begins. This involves sampling the on-state voltage drop of one or more lower transistors, for example, sampling the on-state voltage drops of lower transistors VT4 and VT6 to obtain the on-state voltage drops Vdsu_on and Vdsv_on, which are then saved. When the sampling timer reaches Ta+Tdelay, the second sampling window time Ts2 begins. At this time, the sampling timer's timing is set to Ts2+Tdelay, and the sampling timer starts. Simultaneously, sampling begins for the on-state voltage drop of the lower transistor VT6, the off-state voltage drop of the lower transistor VT4, and the DC bus current Idc. This yields the on-state voltage drop Vdsv_on of the lower transistor VT6, the off-state voltage drop Vdsu_off of the lower transistor VT4, and the U-phase current Iu, which are then saved. When the sampling timer reaches Ts2+Tdelay, the third sampling window time Ts3 begins. At this time, sampling begins for the off-state voltage drops of the lower transistors VT4 and VT6, as well as the DC bus current Idc. This yields the off-state voltage drops Vdsu_off and Vdsv_off of the lower transistors VT4 and VT6, and the W-phase current Iw, which are then saved. When an overflow interrupt occurs in the triangular wave timer (i.e., when the PWM overflow interrupt begins), the fourth sampling window time Ts4 begins, and sampling of the turn-off transistor voltage drop of the lower transistor starts. This involves sampling the turn-off transistor voltage drop of one or more lower transistors, for example, sampling the turn-off transistor voltage drops of lower transistors VT4 and VT6 to obtain the turn-off transistor voltage drops Vdsu_off and Vdsv_off, which are then saved. This completes all sampling for one carrier cycle.

[0155] Then, the V-phase current Iv can be calculated according to Iu+Iv+Iw=0, thereby obtaining the three-phase currents Iu, Iv and Iw of the motor outside the current detection blind zone. Based on the relationship between the three-phase current of the motor and the conduction current of the lower tube, the conduction current of the lower tube can be obtained, that is, the conduction current of the lower tube is Iu, Iv and Iw. Then, based on the conduction current of the lower tube and the conduction voltage drop Vdsu_on and Vdsv_on of the lower tube, the conduction resistance of the lower tube VT4 and VT6 can be calculated by the aforementioned formula (2) and saved. At the same time, Vdsw_off can be calculated based on Vdsu_off+Vdsv_off+Vdsw_off=0, and the three-phase output line voltages Vuv, Vvw and Vwu of the motor and the DC bus voltage Vdc can be obtained by the aforementioned formulas (8) and (9) and saved.

[0156] Next, the next carrier cycle begins. Assuming the next carrier cycle falls within the current detection blind zone, current sampling is not performed at this time. Instead, the three-phase current of the motor within the current detection blind zone is obtained based on the previously acquired on-resistance of the lower transistors of phases U and V. Simultaneously, the three-phase output line voltage and DC bus voltage are also acquired. Specifically, when the triangular wave timer experiences an underflow interrupt (i.e., the PWM underflow interrupt begins), the first sampling window time Ts1 is entered. At this time, the timing of the sampling timer is set to Ta+Tdelay, and the sampling timer is started. Simultaneously, sampling of the on-state voltage drop of the lower transistors begins, sampling the on-state voltage drop of one or more lower transistors. For example, sampling the on-state voltage drops of lower transistors VT4 and VT6 yields the on-state voltage drops Vdsu_on and Vdsv_on (assuming the first sampling window time Ts1 is long enough to sample two), and these are saved. When the sampling timer reaches Ta+Tdelay, the second sampling window time Ts2 begins. At this time, the sampling timer's timing is set to Ts2+Tdelay, and the sampling timer starts. Simultaneously, sampling of the turn-off voltage drop of the lower transistor VT4 begins, obtaining the turn-off voltage drop Vdsu_off of VT4 (assuming the second sampling window time Ts2 is long), and saving it. When the sampling timer reaches Ts2+Tdelay, the third sampling window time Ts3 begins. Since the third sampling window time Ts3 is short (assuming it is less than the minimum current sampling time tmin), no sampling occurs at this time. When an overflow interrupt occurs in the triangular wave timer, i.e., when the PWM overflow interrupt begins, the fourth sampling window time Ts4 begins, and sampling of the turn-off voltage drop of the lower transistor begins. This involves sampling the turn-off voltage drop of one or more lower transistors, for example, sampling the turn-off voltage drop of the lower transistor VT6 to obtain the turn-off voltage drop Vdsv_off (assuming the fourth sampling window time Ts4 is short), and saving it. This completes all sampling for one carrier cycle.

[0157] Then, based on the on-state voltage drops Vdsu_on and Vdsv_on of the lower transistor and the on-state resistance of the corresponding lower transistor calculated at the end of the first carrier cycle, the on-state current of the lower transistor, i.e., the two-phase currents Iu' and Iv' of the motor, is calculated using the aforementioned formula (4), and Iw' is calculated based on Iu' and Iv'. It should be noted that the ratio between the standard on-state resistance of the switching transistor and the calculated on-state resistance can also be calculated at the end of the first carrier cycle. Then, at the end of the carrier cycle, the initial three-phase current is calculated based on the on-state voltage drops Vdsu_on and Vdsv_on of the lower transistor and the standard on-state resistance. Then, the ratio is used to correct the initial three-phase current to obtain the three-phase currents Iu', Iv' and Iw' of the motor. Meanwhile, Vdsw_off is calculated based on the voltage drop of the turn-off tube Vdsu_off and Vdsv_off of the lower tube, and Vdsw_off is calculated based on the voltage drop of the turn-off tube Vdsu_off and Vdsv_off of the lower tube. The three-phase output line voltages Vuv, Vvw and Vwu of the motor and the DC bus voltage Vdc are obtained through the above formulas (8) and (9) and saved.

[0158] Next, in the next carrier cycle, the aforementioned process is repeated. The three-phase currents Iu, Iv, and Iw outside the current detection blind zone and the three-phase currents Iu', Iv', and Iw' inside the current detection blind zone are synthesized to obtain the complete three-phase current as the three-phase feedback current of the motor and saved so as to control the motor based on the three-phase feedback current, such as performing FOC current loop control. At the same time, the motor is controlled based on the three-phase output line voltages Vuv, Vvw, and Vwu and the DC bus voltage Vdc. For example, the flux linkage observer is estimated using the three-phase output line voltages Vuv, Vvw, and Vwu, and the voltage vector width and conduction time of the PWM are calculated using the DC bus voltage Vdc when the SVPWM output voltage is applied.

[0159] In the above embodiments, the deviation problem of current detection and reconstruction using the internal resistance of the switching transistor due to temperature changes is corrected by the current time-division sampling technology. It also achieves the detection of multiple input voltage variables in the FOC calculation process. On the one hand, it avoids harmonics and motor noise from single-resistor current sampling; on the other hand, it reduces the voltage sampling circuit, achieving multiple uses and possessing high engineering application value. Furthermore, as can be seen from the foregoing analysis, when reconstructing the three-phase current of the motor using the conduction voltage drops of the two lower transistors, the number of time windows for obtaining the conduction voltage drops of the lower transistors can be reduced in some cases. For example, the conduction voltage drops of the two lower transistors can be obtained within one or two time windows, instead of obtaining the conduction voltage drops of the three lower transistors from two or three time windows. This reduces the time deviation in obtaining the conduction voltage drops, making the reconstructed three-phase current closer to the true value, ensuring the accuracy of the three-phase current, and further reducing costs.

[0160] In summary, the single-resistance detection method according to embodiments of the present invention acquires or corrects the current in the current detection blind zone when using single-resistance current sampling to obtain three-phase current by real-time sampling of the conduction voltage drop of the lower tube. At the same time, it acquires the three-phase output line voltage and DC bus voltage by real-time sampling of the turn-off voltage drop of the lower tube in a staggered manner. Thus, by sharing the tube voltage drop sampling circuit of the lower tube, not only is the current sampling error improved, but when the motor is controlled based on the three-phase output line voltage, the voltage error problem of the flux linkage observer input can be solved. It is truly multi-purpose, simple, and easy to implement in engineering applications.

[0161] Figure 5 This is a schematic flowchart illustrating a motor control method according to an embodiment of the present invention. (Reference) Figure 5 As shown, the motor control method may include the following steps:

[0162] Step S110: Perform the single-resistance detection method in the aforementioned motor control system to obtain the three-phase feedback current and three-phase output line voltage of the motor.

[0163] Specifically, refer to Figure 6 As shown, during motor control, based on the aforementioned single-resistance detection method, the three-phase current of the motor outside the current detection blind zone can be obtained through the non-blind zone current restoration module, and the three-phase current of the motor within the current detection blind zone can be obtained through the blind zone current restoration module. Furthermore, the three-phase feedback currents Iu, Iv, and Iw of the motor can be synthesized by the current synthesis and restoration module. Simultaneously, based on the aforementioned single-resistance detection method, the three-phase output line voltages Vuv, Vvw, and Vwu of the motor can be obtained through the terminal voltage sampling and restoration unit. For detailed procedures, please refer to the aforementioned description of the single-resistance detection method; they will not be repeated here.

[0164] Step S120: Perform coordinate transformation on the three-phase feedback current to obtain DC current and quadrature-axis current, and perform coordinate transformation on the three-phase output line voltage to obtain direct-axis voltage and quadrature-axis voltage.

[0165] Specifically, refer to Figure 6 As shown, the three-phase feedback currents Iu, Iv, and Iw can be transformed into DC current Id and quadrature-axis current Iq through the coordinate transformation module and saved; at the same time, the three-phase output line voltages Vuv, Vvw, and Vwu can be transformed into direct-axis voltage Vd and quadrature-axis voltage Vq through the coordinate transformation module and saved.

[0166] Step S130: Based on the DC current and quadrature axis current, as well as the direct axis voltage and quadrature axis voltage, the flux linkage and speed are observed to obtain the rotor angle and rotor speed of the motor.

[0167] Specifically, refer to Figure 6 As shown, the DC current Id, quadrature axis current Iq, direct axis voltage Vd, and quadrature axis voltage Vq can be input into the flux linkage and speed observer to perform flux linkage and speed calculations without position sensors, thereby obtaining the rotor speed ω. The rotor speed ω is then converted into the motor rotor angle θ using an integration module. This rotor angle θ can be used for coordinate transformation and PWM signal generation.

[0168] Step S140: Perform vector control on the motor based on the DC current and quadrature shaft current, as well as the rotor angle and rotor speed.

[0169] Specifically, refer to Figure 6 As shown, the difference between the rotor speed setpoint ω* and the rotor speed ω is first calculated, and the difference is then adjusted by the speed loop PI controller to obtain the quadrature axis current setpoint Iq*. Next, the difference between the quadrature axis current setpoint Iq* and the quadrature axis current Iq is calculated, and the difference is adjusted by the flux linkage current loop PI controller to obtain the quadrature axis voltage setpoint. Simultaneously, the difference between the direct axis current setpoint Id* and the direct axis current Id is calculated, and the difference is adjusted by the torque current loop PI controller to obtain the direct axis voltage setpoint. Finally, based on the quadrature axis voltage setpoint, the direct axis voltage setpoint, and the rotor angle θ, a PWM signal is generated through coordinate transformation and the SVPWM control module to control the motor.

[0170] In some embodiments of the present invention, the DC bus voltage is obtained based on the aforementioned single-resistance detection method, and the motor is controlled by generating a PWM signal through coordinate transformation and the SVPWM control module based on the DC bus voltage, quadrature-axis voltage setpoint, direct-axis voltage setpoint, and rotor angle θ.

[0171] In the above embodiments, based on the aforementioned single-resistor detection method, the three-phase current outside the dead zone is obtained by sampling with a single resistor, and the three-phase current inside the dead zone is obtained based on the on-state voltage drop and on-resistance of the lower transistor. This effectively restores the three-phase feedback current of the motor, and eliminates the need for PWM phase shifting, thus avoiding the increased motor noise caused by using PWM phase shifting for current detection in the dead zone. Furthermore, using a single resistor for current sampling avoids the high cost and additional power consumption associated with using multiple resistors. Simultaneously, the three-phase feedback current of the motor is obtained based on the on-state voltage drop of the lower transistor. Obtaining the three-phase output line voltage effectively solves the problem of large errors between the actual and estimated voltages caused by the use of internally calculated command voltages by the flux linkage and speed observer during vector control. This leads to a decrease in control performance, such as low speed accuracy and small control range at low speeds. It effectively improves the lower speed limit range and control accuracy of speed control. At the same time, the DC bus voltage can be obtained from the voltage drop of the turn-off transistor, and the voltage vector pulse width and conduction time can be calculated based on the DC bus voltage. There is no need to set up a DC bus voltage detection unit, which effectively reduces cost and space occupation.

[0172] Figure 7 This is a schematic flowchart of a motor control method according to another embodiment of the present invention. (See reference...) Figure 7 As shown, the motor control method may include the following steps:

[0173] Step S210: Execute the single-resistance detection method in the aforementioned motor control system to obtain the three-phase feedback current of the motor.

[0174] Specifically, refer to Figure 8 As shown, during motor control, based on the aforementioned single-resistance detection method, the three-phase current of the motor outside the current detection blind zone can be obtained through the non-blind zone current restoration module, and the three-phase current of the motor within the current detection blind zone can be obtained through the blind zone current restoration module. Furthermore, the three-phase feedback currents Iu, Iv, and Iw of the motor can be obtained by combining the three-phase currents outside and within the current detection blind zone through the current synthesis and restoration module. For details, please refer to the aforementioned description of the single-resistance detection method; it will not be repeated here.

[0175] Step S220: Perform coordinate transformation on the three-phase feedback current to obtain the DC current and quadrature-axis current.

[0176] Specifically, refer to Figure 8 As shown, the three-phase feedback currents Iu, Iv, and Iw can be transformed into DC current Id and quadrature-axis current Iq through the coordinate transformation module and then saved.

[0177] Step S230: The angle of the motor is identified to obtain the rotor angle and rotor speed of the motor.

[0178] Specifically, the position of the motor rotor can be obtained through a position sensor, and the rotor angle and rotor speed of the motor can be obtained by identifying the rotor position through an angle identification module and an integration module.

[0179] Step S240: Perform vector control on the motor based on the DC current and quadrature shaft current, as well as the rotor angle and rotor speed.

[0180] Specifically, refer to Figure 8 As shown, the difference between the rotor speed setpoint ω* and the rotor speed ω is first calculated, and the difference is then adjusted by the speed loop PI controller to obtain the quadrature axis current setpoint Iq*. Next, the difference between the quadrature axis current setpoint Iq* and the quadrature axis current Iq is calculated, and the difference is adjusted by the flux linkage current loop PI controller to obtain the quadrature axis voltage setpoint. Simultaneously, the difference between the direct axis current setpoint Id* and the direct axis current Id is calculated, and the difference is adjusted by the torque current loop PI controller to obtain the direct axis voltage setpoint. Finally, based on the quadrature axis voltage setpoint, the direct axis voltage setpoint, and the rotor angle θ, a PWM signal is generated through coordinate transformation and the SVPWM control module to control the motor.

[0181] In the above embodiments, based on the aforementioned single-resistor detection method, the three-phase current outside the dead zone is obtained by sampling with a single resistor, and the three-phase current inside the dead zone is obtained by the on-state voltage drop and on-resistance when the lower transistor is turned on. This effectively restores the three-phase feedback current of the motor, and eliminates the need for PWM phase shifting, thus avoiding the problem of increased motor noise caused by using PWM phase shifting for current detection in the dead zone. At the same time, using a single resistor for current sampling avoids the problems of high current sampling cost and additional power consumption caused by using multiple resistors for current sampling. Furthermore, the DC bus voltage can be obtained from the off-state voltage drop of the lower transistor, and the voltage vector pulse width and conduction time can be calculated based on the DC bus voltage, eliminating the need for a DC bus voltage detection unit and effectively reducing cost and space occupation.

[0182] In some embodiments of the present invention, a motor controller is also provided, including a memory, a processor, and a single resistance detection program for a motor control system stored in the memory and executable on the processor. When the processor executes the single resistance detection program, it implements the aforementioned single resistance detection method for a motor control system.

[0183] According to the motor controller of the present invention, based on the aforementioned single-resistance detection method, the current in the current detection blind zone when obtaining three-phase current by sampling the conduction voltage drop of the lower transistor in real time is acquired or corrected by sampling the current drop of the lower transistor in real time. At the same time, the three-phase output line voltage and DC bus voltage are acquired by sampling the turn-off voltage drop of the lower transistor in real time by means of staggered timing. Thus, by sharing the lower transistor's transistor voltage drop sampling circuit, not only is the current sampling error improved, but the voltage error problem of the flux linkage observer input can also be solved. It is truly multi-purpose, and the method is simple and easy to implement in engineering applications.

[0184] In some embodiments of the present invention, a computer-readable storage medium is also provided, on which a single resistance detection program for a motor control system is stored, which, when executed by a processor, implements the aforementioned single resistance detection method for a motor control system.

[0185] According to the computer-readable storage medium of the present invention, based on the aforementioned single-resistance detection method, the current in the current detection blind zone when obtaining three-phase current by sampling the on-state voltage drop of the lower transistor in real time is acquired or corrected by sampling the current drop of the lower transistor in real time. At the same time, the three-phase output line voltage and DC bus voltage are acquired by sampling the off-state voltage drop of the lower transistor in real time by means of timing stagger. Thus, by sharing the lower transistor's transistor voltage drop sampling circuit, not only is the current sampling error improved, but the voltage error problem of the flux linkage observer input can also be solved. It is truly multi-purpose, and the method is simple and easy to implement in engineering applications.

[0186] In some embodiments of the present invention, a motor control system is also provided.

[0187] refer to Figure 1a or Figure 1b As shown, the motor control system includes: a three-phase inverter bridge 10, a current detection unit 20, at least two voltage detection units (such as some or all of the first voltage detection unit 30, the second voltage detection unit 40, and the third voltage detection unit 50) and a control unit (not specifically shown in the figure).

[0188] The three-phase inverter bridge 10 is connected between the DC buses and drives the motor. The current detection unit 20 includes a single sampling resistor R, which is positioned at the negative terminal of the DC bus and used to detect the DC bus current. At least two voltage detection units are positioned at the lower transistors of at least two phase arms of the three-phase inverter bridge and are used to sample the conduction voltage drop when the lower transistor of at least one phase arm of the three-phase inverter bridge is turned on. Figure 1aAs shown, the first voltage detection unit 30 corresponds to the lower tube setting of the U-phase bridge arm in the three-phase inverter bridge 10 and is used to detect the voltage drop of the lower tube of the U-phase bridge arm; the second voltage detection unit 40 corresponds to the lower tube setting of the V-phase bridge arm in the three-phase inverter bridge 10 and is used to detect the voltage drop of the lower tube of the V-phase bridge arm; the third voltage detection unit 50 corresponds to the lower tube setting of the W-phase bridge arm in the three-phase inverter bridge 10 and is used to detect the voltage drop of the lower tube of the W-phase bridge arm. The control unit is used to determine the conduction current when the lower tube of at least one phase arm of the three-phase inverter bridge is turned on based on the DC bus current, and to obtain the conduction tube voltage drop when the lower tube of at least one phase arm of the three-phase inverter bridge is turned on, and to determine the conduction resistance when the lower tube of at least one phase arm of the three-phase inverter bridge is turned on based on the conduction current and the conduction tube voltage drop, and to determine the three-phase current outside the current detection blind zone based on the DC bus current, and to determine the three-phase current inside the current detection blind zone based on the conduction tube voltage drop and the conduction resistance; the control unit is also used to determine the three-phase feedback current of the motor based on the three-phase current outside the current detection blind zone and the three-phase current inside the current detection blind zone.

[0189] In some embodiments of the present invention, at least two voltage detection units are further configured to sample the voltage drop of the turn-off transistor when the lower transistor of at least one phase arm of the three-phase inverter bridge is turned off; the control unit is further configured to obtain the voltage drop of the turn-off transistor when the lower transistor of at least one phase arm of the three-phase inverter bridge is turned off, and determine the three-phase output line voltage and DC bus voltage of the motor based on the voltage drop of the turn-off transistor.

[0190] In some embodiments of the present invention, at least two voltage detection units include two voltage detection units or three voltage detection units.

[0191] In some embodiments of the present invention, the control unit is further configured to: perform coordinate transformation on the three-phase feedback current to obtain DC current and quadrature-axis current; perform coordinate transformation on the three-phase output line voltage to obtain direct-axis voltage and quadrature-axis voltage; perform flux linkage and speed observation based on the DC current and quadrature-axis current, as well as the direct-axis voltage and quadrature-axis voltage, to obtain the rotor angle and rotor speed of the motor; and perform vector control on the motor based on the DC current and quadrature-axis current, as well as the rotor angle and rotor speed.

[0192] In some embodiments of the present invention, the control unit is further configured to: perform coordinate transformation on the three-phase feedback current to obtain DC current and quadrature-axis current; perform angle identification on the motor to obtain the rotor angle and rotor speed of the motor; and perform vector control on the motor based on the DC current and quadrature-axis current, as well as the rotor angle and rotor speed.

[0193] In some embodiments of the present invention, the first voltage detection unit 30, the second voltage detection unit 40, and the third voltage detection unit 50 have the same structure, as shown in the reference. Figure 9As shown, it specifically includes: a voltage divider circuit 61, a turn-off voltage detection circuit 62, a turn-on voltage detection circuit 63, and a filter 64. The turn-off voltage detection circuit 62 has the ability to detect the turn-off voltage, and the turn-on voltage detection circuit 63 has the ability to detect the turn-on voltage. The turn-off voltage detection circuit 62 and the turn-on voltage detection circuit 63 share the voltage divider circuit 61 and the filter 64, which can significantly reduce the number of circuit components used, and is beneficial to reducing costs and space occupation.

[0194] It should be noted that for other descriptions of the motor control system, please refer to the aforementioned single-resistance detection method and motor control method; details will not be repeated here.

[0195] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0196] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0197] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0198] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0199] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0200] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for detecting a single resistor in a motor control system, characterized in that, The motor control system includes a three-phase inverter bridge for driving the motor and a single sampling resistor corresponding to the negative terminal of the DC bus. The method includes: Obtain the DC bus current flowing through the single sampling resistor, and determine the conduction current when the lower tube of at least one phase arm of the three-phase inverter bridge is turned on based on the DC bus current. Obtain the voltage drop across the conduction tube when the lower tube of at least one phase arm of the three-phase inverter bridge is turned on; The on-resistance of the lower tube of at least one phase arm of the three-phase inverter bridge when it is turned on is determined based on the on-current and voltage drop of the lower tube of at least one phase arm of the three-phase inverter bridge. The three-phase current outside the current detection blind zone is determined based on the DC bus current, and the three-phase current inside the current detection blind zone is determined based on the voltage drop of the conducting tube and the conducting resistance. The three-phase feedback current of the motor is determined based on the three-phase current outside the current detection blind zone and the three-phase current inside the current detection blind zone. Before obtaining the DC bus current and the voltage drop across the conducting tube, the method further includes: The first sampling window time, the second sampling window time, and the third sampling window time are determined. The first sampling window time is the time from the underflow interruption of the PWM triangular wave to the turn-on of the upper transistor of any one phase arm of the three-phase inverter bridge. The second sampling window time is the time from the turn-on of the upper transistor of any one phase arm of the three-phase inverter bridge after a first preset time delay to the turn-on of the upper transistor of the next phase arm of the three-phase inverter bridge. The third sampling window time is the time from the turn-on of the upper transistor of the next phase arm of the three-phase inverter bridge after a first preset time delay to the turn-on of the upper transistor of the last phase arm of the three-phase inverter bridge.

2. The method according to claim 1, characterized in that, Determining the conduction current when the lower switch of at least one phase arm of the three-phase inverter bridge is turned on based on the DC bus current includes: During the second sampling window time and the third sampling window time, the DC bus current is sampled to obtain the phase current of the motor, and the conduction current when the lower tube of at least one phase arm of the three-phase inverter bridge is turned on is determined based on the phase current of the motor.

3. The method according to claim 1, characterized in that, Obtaining the conduction voltage drop of at least one phase arm of the three-phase inverter bridge when the lower tube is turned on includes: During at least one of the first sampling window time, the second sampling window time, and the third sampling window time, the conduction tube voltage drop is sampled to obtain the conduction tube voltage drop when the lower tube of at least one phase arm of the three-phase inverter bridge is turned on.

4. The method according to any one of claims 1-3, characterized in that, The voltage drop across the conductive tube includes the voltage drop across the conductive tube when the lower tube of either a two-phase or a three-phase arm of the three-phase inverter bridge is conducting.

5. The method according to any one of claims 1-3, characterized in that, Also includes: Obtain the voltage drop across the turn-off tube when the lower tube of at least one phase arm of the three-phase inverter bridge is turned off; The three-phase output line voltage and DC bus voltage of the motor are determined based on the voltage drop of the shut-off transistor.

6. The method according to claim 5, characterized in that, Before obtaining the voltage drop across the shut-off tube, the method further includes: The second sampling window time, the third sampling window time, and the fourth sampling window time are determined. The second sampling window time is the time from when the upper tube of any phase arm of the three-phase inverter bridge is turned on and delayed by a first preset time until the upper tube of the next phase arm of the three-phase inverter bridge is turned on. The third sampling window time is the time from when the upper tube of the next phase arm of the three-phase inverter bridge is turned on and delayed by a first preset time until the upper tube of the last phase arm of the three-phase inverter bridge is turned on. The fourth sampling window time is the time from when the overflow interruption of the PWM triangular wave occurs until the upper tube of any phase arm of the three-phase inverter bridge is turned off.

7. The method according to claim 6, characterized in that, Obtaining the turn-off voltage drop when the lower switch of at least one phase arm of the three-phase inverter bridge is turned off includes: During at least one of the second sampling window time, the third sampling window time, and the fourth sampling window time, the turn-off tube voltage drop is sampled to obtain the turn-off tube voltage drop when the lower tube of at least one phase arm of the three-phase inverter bridge is turned off.

8. The method according to claim 5, characterized in that, The shut-off tube voltage drop includes the shut-off tube voltage drop when the lower tube of two-phase or three-phase bridge arm in the three-phase inverter bridge is turned off.

9. A motor control method, characterized in that, include: The single-resistance detection method in the motor control system according to any one of claims 1-8 is executed to obtain the three-phase feedback current and three-phase output line voltage of the motor; The coordinate transformation of the three-phase feedback current is performed to obtain the DC current and quadrature-axis current, and the coordinate transformation of the three-phase output line voltage is performed to obtain the direct-axis voltage and quadrature-axis voltage. Based on the DC current and quadrature axis current, as well as the direct axis voltage and quadrature axis voltage, flux linkage and speed are observed to obtain the rotor angle and rotor speed of the motor; The motor is vector controlled based on the DC current and quadrature-axis current, as well as the rotor angle and rotor speed.

10. A motor control method, characterized in that, include: The three-phase feedback current of the motor is obtained by performing the single-resistance detection method in the motor control system according to any one of claims 1-8. The three-phase feedback current is transformed by coordinates to obtain the DC current and quadrature-axis current. The motor is angle-identified to obtain the rotor angle and rotor speed. The motor is vector controlled based on the DC current and quadrature-axis current, as well as the rotor angle and rotor speed.

11. A motor controller, characterized in that, The method includes a memory, a processor, and a single resistance detection program for a motor control system stored in the memory and executable on the processor. When the processor executes the single resistance detection program, it implements the single resistance detection method for a motor control system according to any one of claims 1-8.

12. A computer-readable storage medium, characterized in that, It stores a single resistance detection program in a motor control system, which, when executed by a processor, implements the single resistance detection method in a motor control system according to any one of claims 1-8.

13. A motor control system, wherein the system implements the single resistance detection method in the motor control system according to any one of claims 1-8, characterized in that, include: A three-phase inverter bridge is connected between DC buses and drives a motor to operate. A current detection unit, comprising a single sampling resistor, wherein the single sampling resistor is configured corresponding to the negative terminal of the DC bus and is used to detect the DC bus current; At least two voltage detection units are provided, each corresponding to the lower tube of at least two phase arms of the three-phase inverter bridge, for sampling the conduction tube voltage drop when the lower tube of at least one phase arm of the three-phase inverter bridge is turned on. The control unit is configured to determine the on-state current when the lower tube of at least one phase arm of the three-phase inverter bridge is turned on based on the DC bus current, and to obtain the on-state voltage drop when the lower tube of at least one phase arm of the three-phase inverter bridge is turned on, and to determine the on-state resistance when the lower tube of at least one phase arm of the three-phase inverter bridge is turned on based on the on-state current and the on-state voltage drop, and to determine the three-phase current outside the current detection blind zone based on the DC bus current, and to determine the three-phase current within the current detection blind zone based on the on-state voltage drop and the on-state resistance; The control unit is further configured to determine the three-phase feedback current of the motor based on the three-phase current outside the current detection blind zone and the three-phase current within the current detection blind zone.

14. The motor control system according to claim 13, characterized in that, At least two of the voltage detection units are also used to sample the turn-off voltage drop when the lower switch of at least one phase arm of the three-phase inverter bridge is turned off; The control unit is also used to obtain the turn-off tube voltage drop when the lower tube of at least one phase arm of the three-phase inverter bridge is turned off, and to determine the three-phase output line voltage and DC bus voltage of the motor based on the turn-off tube voltage drop.

15. The motor control system according to claim 13 or 14, characterized in that, The at least two voltage detection units include two voltage detection units or three voltage detection units.

16. The motor control system according to claim 14, characterized in that, The control unit is also used for, The coordinate transformation of the three-phase feedback current is performed to obtain the DC current and quadrature-axis current, and the coordinate transformation of the three-phase output line voltage is performed to obtain the direct-axis voltage and quadrature-axis voltage. Based on the DC current and quadrature axis current, as well as the direct axis voltage and quadrature axis voltage, flux linkage and speed are observed to obtain the rotor angle and rotor speed of the motor; The motor is vector controlled based on the DC current and quadrature-axis current, as well as the rotor angle and rotor speed.

17. The motor control system according to claim 13, characterized in that, The control unit is also used for, The three-phase feedback current is transformed by coordinates to obtain the DC current and quadrature-axis current. The motor is angle-identified to obtain the rotor angle and rotor speed. The motor is vector controlled based on the DC current and quadrature-axis current, as well as the rotor angle and rotor speed.

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