Hybrid single-phase current sensor control strategy for permanent magnet synchronous motor

Abstract

A method for operating a motor drive to supply power to a motor includes: determining a first voltage command based on a torque command and an electrical speed; measuring a phase current in the electric machine; determining an estimated motor current based on the phase current; verifying the accuracy of the estimated motor current; determining a second voltage command based on the estimated motor current; calculating a reconstructed alpha-axis current based on the phase current; determining a difference between the measured phase current and the reconstructed alpha-axis current as an estimated error; comparing the estimated error to an error threshold to determine an estimation condition; selecting one of the first voltage command or the second voltage command as a final voltage command based on an estimation condition; and controlling the inverter to supply AC power to the motor based on the final voltage command.

Description

Cross-application of related applications

[0001] This PCT international patent application claims the benefit and priority of U.S. Provisional Patent Application Serial No. 63 / 545,409, filed on October 24, 2023, entitled “Hybrid Single-Phase Current Sensor Control Strategy For Permanent Magnet Synchronous Machines,” the entire disclosure of which is incorporated herein by reference. Technical Field

[0002] This disclosure generally relates to methods and systems for controlling motor drives. More specifically, the methods and systems of this disclosure can be used to control a motor drive coupled to a motor configured as a traction motor for propelling a motor vehicle, such as a bus or truck. Background Technology

[0003] Permanent magnet synchronous motors (PMSMs) are widely used in servo control, automotive, aerospace, and wind power systems due to their high power density, high efficiency, and simple structure. PMSMs are typically driven by voltage source inverters and use inputs such as current, position, and / or voltage measurements to perform motor control.

[0004] Field-oriented control (FOC) is a well-known control method for PMSMs. An FOC drive system may include a PMSM driven by a voltage source inverter, and motor control is based on inputs including current, position, and / or voltage measurements. Two or three hardware phase current sensors are typically used for current measurement in FOC drive systems. However, such hardware phase current sensors can be expensive. This includes not only the cost of the sensors themselves, but also wiring, appropriate connectors and interfaces, and all associated costs. Furthermore, current sensors can fail due to physical damage or environmental conditions, which can affect the performance of the control system and even lead to downtime. This can be particularly problematic in EV applications. Therefore, employing a reliable control strategy to ensure continuous operation of the motor drive system is crucial when some of the current sensors fail to serve. Thus, a single current sensor (SCS) control strategy may be advantageous for both reducing costs and improving the robustness of the motor drive system.

[0005] SCS (Search Engine Control) methods can reconstruct three-phase current signals using a single DC-link current sensor or a single-phase current sensor, enabling closed-loop current control in PMSM (Motor Motor Module) drive systems. For DC-link current sensor-based SCS control, additional effort may be required to compensate for dead time. Furthermore, DC-link current sensors may not be available for all three-phase motor drive systems. Observer-based SCS control systems can use a current state observer to reconstruct the three-phase motor current using a single measured phase current. This method requires no additional hardware. By using a current observer, only a single-phase current sensor may be needed, reducing the complexity and cost of the control system. However, observer-based SCS control systems may struggle to accurately determine the phase current at zero speed. With observer-based SCS control, the motor drive system may not generate accurate torque at rest. Therefore, system uncertainties and disturbances cannot be suppressed, and safe startup cannot be guaranteed. Summary of the Invention

[0006] This disclosure provides a method for operating a motor driver to supply power to a motor. The method includes: determining a first voltage command based on a torque command and an electrical speed; measuring a phase current in the motor; determining an estimated motor current based on the phase current; determining a second voltage command based on the estimated motor current; calculating a reconstructed α-axis current based on the phase current; determining an estimation error as the difference between the measured phase current and the reconstructed α-axis current; comparing the estimation error with an error threshold to determine estimation conditions; selecting either the first voltage command or the second voltage command as a final voltage command based on the estimation conditions; and controlling an inverter to supply alternating current (AC) to the motor based on the final voltage command.

[0007] This disclosure also provides a motor drive system. The motor drive system includes: an inverter having at least three pairs of switches operable to supply alternating current (AC) power to a motor; a current sensor configured to measure phase current in the motor; and a controller. The controller is configured to: determine a first voltage command based on a torque command and an electric speed; determine an estimated motor current based on the phase current; determine a second voltage command based on the estimated motor current; calculate a reconstructed α-axis current based on the measured phase current; determine an estimation error as the difference between the phase current and the reconstructed α-axis current; compare the estimation error with an error threshold to determine an estimation condition; select one of the first voltage command or the second voltage command as a final voltage command based on the estimation condition; and control the inverter to supply AC power to the motor based on the final voltage command. Attached Figure Description

[0008] Further details, features, and advantages of the design of the present invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings.

[0009] Figure 1 A schematic block diagram of a system according to one aspect of this disclosure is shown;

[0010] Figure 2 A schematic block diagram of a motor drive system with a current estimator according to one aspect of this disclosure is shown;

[0011] Figure 3 A schematic block diagram of an orthogonal signal generator (OSG) according to one aspect of this disclosure is shown;

[0012] Figure 4 A flowchart illustrating a mode selection method for operating a motor drive system according to one aspect of this disclosure is shown;

[0013] Figures 5A to 5B A graph showing the motor speed and motor torque during operation of the motor drive system as described in this disclosure is presented on a common timescale.

[0014] Figures 6A to 6C The graphs showing the errors of d-axis current, q-axis current, and phase current on a common time scale and when the motor drive system is operated without using an OSG-based correction method are presented.

[0015] Figures 7A to 7C The diagram shows graphs illustrating the errors of d-axis current, q-axis current, and phase current on a common timescale, and when the motor drive system is operated using the OSG-based correction method of this disclosure; and

[0016] Figures 8A to 8C A flowchart illustrating the steps of a method for operating a motor driver according to some embodiments of this disclosure is shown. Detailed Implementation

[0017] The present invention will be described in detail with reference to the accompanying drawings and in view of the following embodiments.

[0018] To overcome the technical limitations of existing methods, this disclosure provides a hybrid SCS control strategy for controlling motor drive systems. The hybrid SCS control strategy can ensure smooth and safe starting of motors with single-phase hardware current sensors.

[0019] In the zero-speed and low-speed range, direct voltage control is used to generate torque, and observer-based SCS control is activated when the estimation error is minimized. However, direct voltage control has inherent limitations because it lacks the ability to dynamically adapt to changing load conditions and changes in motor operating states, resulting in suboptimal performance over a wide speed range. Therefore, a rapid and seamless transition to observer-based SCS control after motor startup becomes crucial.

[0020] At zero speed, the current state observer may suffer from large initial estimation errors due to unobservability issues and parameter mismatch. For safety reasons, it may be important to avoid switching to an observer-based approach before minimizing the current error in the observer. To address this issue, an orthogonal signal generation (OSG) block is also introduced into the proposed hybrid SCS control framework. This OSG block utilizes a single measured A-phase current to construct the β-axis current, thereby enabling rapid correction of the observer estimation error during startup in hybrid SCS control.

[0021] By leveraging the advantages of both control strategies, the motor can operate efficiently and effectively in the zero-speed and low-speed ranges using direct voltage control, and seamlessly switch to observer-based SCS control, enabling enhanced performance and stability across the entire operating range. Additionally, the integration of the OSG block can rapidly correct any errors in current estimation during startup, potentially achieving optimal performance from the outset. This innovative hybrid SCS control strategy not only enhances overall system stability but also ensures reliable and efficient motor operation, making it a promising solution for a wide range of applications in motor drive systems.

[0022] Figure 1A block diagram of a system 10 according to one aspect of this disclosure is shown. System 10 is disposed in a vehicle 12 having four wheels 14. System 10 includes an inverter 20 having one or more pairs of solid-state switches 22, such as field-effect transistors (FETs), configured to switch current from a DC power supply 23 and generate AC power on a set of motor leads 24. The motor leads 24 transmit power between the inverter 20 and a motor 26. The motor 26 may be a permanent magnet synchronous motor (PMSM). The motor 26 is shown as a 3-phase motor; however, the motor 26 may have any number of phases. For example, the motor 26 may be a 3-phase motor or a higher-order multiphase motor. The motor 26 may be used as a motor, a generator, or a motor / generator that is both a motor and a generator. The motor 26 may be coupled to one or more of the wheels 14 of the vehicle 12 for driving the vehicle 12. Alternatively, the motor 26 may be used for one or more auxiliary functions of the vehicle 12, such as for operating actuators, fans, pumps, etc. In some embodiments, the system 10 of this disclosure may have non-transportation applications, such as motor control for industrial or manufacturing applications.

[0023] A current sensor 28 is arranged to measure the phase current in one of the motor leads 24. In some embodiments, and as... Figure 1 As shown, current sensor 28 measures the phase A current on one of the motor leads 24 corresponding to phase A. However, system 10 can measure the current on any of the motor leads 24. System 10 may include other sensors, such as voltage sensors configured to measure the voltage on or between the motor leads 24.

[0024] Figure 1 System 10 also includes an electronic control unit (ECU) 30 that communicates with current sensor 28 to measure current in motor leads 24. ECU 30 can also functionally communicate with inverter 20 to control the operation of inverter 20 and / or monitor parameters measured by sensors associated with inverter 20. ECU 30 includes a processor 32 coupled to storage memory 34. Storage memory 34 stores instructions (such as program code executed by processor 32) in instruction storage device 36. Storage memory 34 also includes a data memory 38 for storing data to be used by processor 32. Data memory 38 can record, for example, values ​​of parameters measured by current sensor 28 and / or results of functions calculated by processor 32.

[0025] Speed / position sensor 42 can measure electrical rotational position The corresponding rotational position of motor 26 Alternatively or additionally, the speed / position sensor 42 can measure the electrical speed of the motor 26. The corresponding rotational speed of motor 26 In some embodiments, the speed / position sensor 42 may include an encoder or resolver connected to the shaft 40 of the motor 26. The speed / position sensor 42 can detect the rotational position of the motor 26. and / or rotational speed Transmitted to ECU 30.

[0026] Figure 2 A schematic block diagram of a motor drive system 100 according to one aspect of this disclosure is shown. The motor drive system 100 includes a controller 102 configured to perform several computational functions. The controller 102 may include an ECU 30 and may implement associated functions in hardware, software, or a combination of hardware and software.

[0027] Controller 102 includes a start controller 103, which is configured to be based on torque commands. and motor speed Generate first voltage command The start controller 103 does not use any current measurement results to generate the first voltage command. First voltage command This includes d-axis and q-axis voltage values ​​representing the voltage applied by inverter 20 to motor 26. Start-up controller 103 can be based on torque commands. and motor speed To calculate the first voltage command For example, the start controller 103 can use the following equation (3) to calculate the first voltage command. Alternatively or additionally, the start controller 103 may use one or more lookup tables to generate the first voltage command. .

[0028] Controller 102 also includes commands configured to generate current. The speed / torque controller 104 can generate current commands using lookup tables or control loops such as proportional-integral (PI) loops or proportional-integral-derivative (PID) loops. The speed / torque controller 104 can be configured as a speed controller to cause the motor 26 to respond to speed commands. With the electric speed of the motor Rotation. Alternatively or additionally, the speed / torque controller 104 can be configured as a torque controller to cause the motor 26 to rotate according to torque commands. It generates output torque.

[0029] The controller 102 also includes a current regulator 106, which is configured to be based on current commands. And based on the estimated current To generate the second voltage command Second voltage command This includes d-axis and q-axis voltage values ​​representing the voltage applied by inverter 20 to motor 26. Current regulator 106 can use a control loop (such as a proportional-integral (PI) loop or a proportional-integral-derivative (PID) loop) to generate a second voltage command. .

[0030] Controller 102 also includes a dq-abc transformer 108, which is configured to provide a final voltage command based on the dq reference frame. And based on the electric rotation position of motor 26 To calculate phase voltage , , The dq-abc transformer 108 can realize inverse direct orthogonal zero transformation, such as the transformation described in equation (8).

[0031] The controller 102 also includes a pulse width modulator (PWM) 110, which is configured to generate a plurality of gate driver signals 112 for controlling the switching devices of the inverter 20, so that the inverter 20 generates signals corresponding to the phase voltage on the motor leads 24. , , AC power.

[0032] Controller 102 also includes a first current selector 120, which is configured to respond to a first voltage command based on an estimated conditional control mode. Or second voltage command One of the ways to set the final voltage command This estimation condition can be represented as a Boolean value. For example, if the estimation condition control mode has a first state such as zero, the first current selector 120 can command the final voltage. Set to equal to the first voltage command Furthermore, if the estimated conditions have a second state such as a non-zero value, the first current selector 120 can deliver the final voltage command. Set to equal the second voltage command .

[0033] The controller 102 also includes a current estimator 130, which is configured to base its calculations on the A-phase current measured from the current sensor 28. To determine the estimated current .

[0034] The current estimator 130 also includes an orthogonal signal generator (OSG) 132, which is configured to base its calculations on the A-phase current measured from the current sensor 28. To calculate the reconstructed α-axis current and reconstructed β-axis current The internal details of the OSG 132 are in Figure 3 It is shown in the figure and described below.

[0035] The current estimator 130 also includes an abc-αβ transformer 134, which is configured to: based on the A-phase current measured from the current sensor 28 Compared with the estimated phase B current and estimated C-phase current The combination of these methods is used to calculate the second α-axis current. Second β-axis current Second α-axis current Second β-axis current They can be indicated by the subscript “mix” because they are each based on a mixture of measured and estimated phase currents. The abc-αβ transformer 134 can realize the inverse of the transformation described in equation (10).

[0036] The current estimator 130 also includes a second current selector 136, which is configured to: control a mode based on estimation conditions, based on the first α-axis current from the OSG 132. and the first β-axis current Or based on the second α-axis current from the abc-αβ transformer 134 Second β-axis current One way to set the selected α-axis current and the selected β-axis current For example, if the estimation conditions have a first state such as zero, the second current selector 136 can select the α axis. and β-axis current Set them to be equal to the first α-axis current. and the first β-axis current If the estimation condition has a second state such as a non-zero value, the second current selector 136 can also select the α-axis current. and β-axis current Set them to be equal to the second α-axis current. Second β-axis current .

[0037] The current estimator 130 also includes an αβ-dq transformer 138, which is configured to be based on the α-axis current selected from the second current selector 136. and β-axis current To calculate the d-axis input current and q-axis input current The αβ-dq transformer 138 can realize the transformation described in equation (9).

[0038] The current estimator 130 also includes a current observer 140, which is configured to be based on the d-axis input current. and q-axis input current Final voltage command The electric speed of motor 26 To calculate the estimated motor current The current observer 140 may include a Luenberger current observer (LCO) structure, as described below, and is represented by equation (15). The estimated motor current... The current is supplied by the current observer 140 to the current regulator 106, which uses the estimated motor current. As a control loop to generate a second voltage command Feedback signals.

[0039] The current estimator 130 also includes a dq-αβ transformer 142, which is configured to be based on the d-axis component of the estimated motor current determined by the current observer 140. and q-axis components To calculate the estimated α-axis current and β-axis current The dq-αβ transformer 142 can realize the transformation described in equation (7).

[0040] The current estimator 130 also includes an αβ-abc transformer 144, which is configured to calculate the estimated α-axis current based on the dq-αβ transformer 142. and β-axis current To calculate the estimated phase current The αβ-abc transformer 144 can realize the transformation described in equation (10).

[0041] At zero speed and low speed (steady state), assuming the d-axis current is zero, the torque generated by the PMSM can be determined using equation (1): in, This is the q-axis current; It is a permanent magnet (PM) flux linkage; The number of pole pairs; This represents the motor torque.

[0042] The dq-axis voltage equation can be simplified and expressed as described in equation (2): in, Represents the d / q axis voltage; It is a q-axis inductor, and It is the speed of electricity.

[0043] Substituting equation (1) into equation (2), we can obtain the reference dq-axis voltage to generate the desired torque for the direct voltage control method as shown in equation (3): Among them, the symbol " "Indicates a reference value."

[0044] Using equation (3), the desired torque can be generated using only voltage commands without any current measurements. However, due to the neglect of current variations and the assumption of zero d-axis current, direct voltage control cannot guarantee good dynamic performance and efficiency, especially for high-speed operation. Therefore, this direct voltage control will only be used to start the motor in the zero-speed and low-speed ranges. In practical applications, the voltage drop across the power devices and the voltage error caused by inverter nonlinearity are not negligible compared to the reference dq-axis voltage values ​​in the zero-speed and low-speed regions. Therefore, it is recommended to use an offline lookup table of the dq-axis reference voltage to obtain accurate torque.

[0045] The current state observer structure in observer-based SCS control can be written as equation (4): in in, and These represent the d-axis current and the q-axis current, respectively. and These represent the d-axis inductance and the q-axis inductance, respectively. For winding resistance; and These represent system uncertainties and unknown external disturbances on the d-axis and q-axis, respectively; is the observer gain matrix; the symbol "^" represents the estimated value, and the superscript "T" indicates the transpose of the matrix.

[0046] To ensure a smooth control transition from direct voltage control to observer-based SCS control, the observer's current error needs to be minimized during the transition. However, due to system disturbances such as parameter mismatch and inverter nonlinearity, the observer may have a large estimation error at zero speed. An effective way to correct the observer's current estimation error at startup is to input the actual current into the observer. Therefore, an orthogonal signal generator (OSG) 132 is used to reconstruct the measured signal and a signal with a 90-degree shift.

[0047] Figure 3 The diagram shows the structure of the OSG 132. The input signal to the OSG 132 is the measured A-phase current. and the electric speed of the motor ( The OSG 132 is used to generate two orthogonal signals. and These two orthogonal signals have the same characteristics as... They have the same amplitude and are 90 degrees phase-shifted from each other.

[0048] The OSG 132 includes a first differential calculator 150, which is configured to read the measured A-phase current. Subtract the reconstructed α-axis current from To determine the phase difference signal of A The OSG 132 also includes a gain calculator 152, which is configured to input the A-phase error signal. Multiply by the predetermined gain value To determine the first intermediate value 153. The OSG 132 also includes a second difference calculator 154, which is configured to subtract the reconstructed β-axis current from the first intermediate value 153. To determine the second intermediate value 155. The OSG 132 also includes a first multiplier 156, which is configured to multiply the second intermediate value 155 by the motor's electrical speed. And determined as the second intermediate value 155 and the electric speed of the motor The third intermediate value 157 is the product of the product. The OSG 132 also includes a first integrator 158, which is configured to calculate the reconstructed α-axis current as the integral of the third intermediate value 157. .

[0049] like Figure 3 As shown, the OSG 132 also includes a second multiplier 160, which is configured to reconstruct the α-axis current. Multiplied by the electric speed of the motor And determine the α-axis current as the reconstructed current. With the electric speed of the motor The fourth intermediate value 161 is the product of the two. The OSG 132 also includes a second integrator 162, which is configured to calculate the reconstructed β-axis current as the integral of the fourth intermediate value 161. .

[0050] based on Figure 3 The closed-loop transfer function related to the input and output relationship in OSG 132 is expressed in equations (5) to (6). In the formula, This is the gain of the OSG 132. Compare equation (6) and equation (5). Showing relative to The OSG 132 achieves a 90-degree phase shift. Therefore, it can efficiently generate two orthogonal signals based on the input reference signal.

[0051] By using the reconstructed αβ axis current and This generates the input dq-axis current for the current observer. Here, the reconstructed α-axis current... The measured A-phase current can be used instead, as they are equivalent. This method facilitates rapid convergence of the observer, effectively corrects for any initial estimation errors, and enables the motor control system to start more smoothly.

[0052] To minimize the observer error and ensure the safety of switching to observer-based SCS control, in Figure 4 The document describes a process 200 based on an OSG-based control mode selection strategy. Process 200 comprises two main steps: Step 1: Evaluate the accuracy of the current signal reconstruction from OSG 132. Step 1 includes calculating the measured phase A current at point 202. The reconstructed α-axis current obtained from OSG 132 The difference between them. The first difference calculator 150 can be used to perform this calculation and determine the A phase difference signal. Step 1 also includes converting the A phase difference signal at position 204. Compared with the first error threshold The comparison indicates the OSG 132's ability to accurately reconstruct the current signal. Step 2: Verify the accuracy of the observer-based signal reconstruction Once the accuracy of the current signal of the OSG reconstructed by OSG 132 is determined, the next step involves measuring the estimated β-axis current at 206 using the current estimated from current observer 140. Subtract the reconstructed β-axis current from Determine the β axis difference signal Step 2 also includes converting the β-axis difference signal at 208. With the second error threshold The comparison indicates the ability of the current observer 140 to accurately reconstruct the current signal.

[0053] As shown in the figure, process 200 includes setting the estimation condition control mode to zero in response to the difference signal corresponding to either of the comparisons at 204 or 208 being not less than the corresponding threshold. As also shown in the figure, process 200 further includes setting the estimation condition control mode to one (i.e., a non-zero value) in response to the difference signals corresponding to both comparisons at 204 or 208 being less than the corresponding threshold.

[0054] By implementing this control mode switching strategy, the reliability of switching to observer-based SCS control can be determined. When the estimated condition control_mode is set to zero (i.e., control_mode = 0), direct voltage control mode is used; when the estimated condition control_mode is set to a non-zero value (e.g., control_mode = 1), control is switched to observer-based SCS control mode. Figure 2 The overall block diagram of the proposed hybrid SCS control framework is provided in the document. Figure 2 The coordinate transformations in the equations are defined as shown in equations (7), (8), (9), and (10):

[0055] Figure 2 The transformation matrix used in the transformation block , , ,and They are defined as equations (7), (8), (9) and (10), respectively. in, This indicates the position of the electric rotor. Observer-based current estimation

[0056] Considering system uncertainties and unknown external disturbances, the machine equations of the PMSM in the rotating orthogonal (dq) reference frame can be expressed as shown in equations (11) and (12): Among them, u d and u q These represent the d-axis voltage and the q-axis voltage, respectively; i d and i q These represent the d-axis current and the q-axis current, respectively; L d and L q These represent the d-axis inductance and the q-axis inductance, respectively. It is a permanent magnet flux linkage; For winding resistance; f is the electric speed of the motor. d and f q These represent system uncertainties and unknown external disturbances on the d-axis and q-axis, respectively; , , and This refers to the parameter variation between the actual motor parameters and the corresponding nominal parameters. E d and E q These represent the unknown external disturbance terms along the d-axis and q-axis, respectively.

[0057] Assuming that the changes in resistance, inductance, permanent magnet flux linkage, and external disturbances are small and negligible, the dynamic equation of the internal PMSM (IPMSM) on the dq axis can be expressed as equation (13):

[0058] The developed PMSM state-space model is given as shown in equation (14): Where A, B, and C are each defined as: , and among them It is a state vector. It is the input vector, and It is the output vector.

[0059] The observer structure can be written as equation (15): in, is the observer gain matrix, and the superscript T denotes the transpose of the matrix; k1, k2, ..., k8 are the observer gain coefficients. The symbol "^" indicates an estimated value. In the Luenberger observer, the dynamic performance of the system is determined by the eigenvalues ​​of (A-KC). in, Let ζ represent the natural frequency of the observer, and let ζ represent the damping ratio of the observer.

[0060] Figures 5A to 5B A graph showing the motor speed and motor torque during operation of the motor drive system as described in this disclosure is presented on a common timescale. Figure 5A The first curve, 220, shows the motor speed (in revolutions per minute) over time. Figure 5BA second curve 222 showing the actual motor torque and a third curve 224 showing the reference torque at the same time scale are shown.

[0061] Figures 6A to 6C The graphs show the errors of d-axis current, q-axis current, and phase current on a common time scale and when the motor drive system is operated without using an OSG-based correction method. Figure 6A The first curve 230 of the actual d-axis current and the second curve 232 of the estimated d-axis current are shown. Figure 6B The third curve 234 shows the actual q-axis current and the fourth curve shows the estimated q-axis current. Figure 6C The fifth curve 238 for the A-phase current estimation error, the sixth curve 240 for the B-phase current estimation error, and the seventh curve 242 for the C-phase current estimation error are shown.

[0062] Figures 7A to 7C The graphs showing the errors of d-axis current, q-axis current, and phase current on a common timescale and when operating a motor drive system using the OSG-based correction method of this disclosure are presented. Figure 7A The first curve 250 of the actual d-axis current and the second curve 252 of the estimated d-axis current are shown. Figure 7B The third curve (254) showing the actual q-axis current and the fourth curve showing the estimated q-axis current are illustrated. Figure 7C The fifth curve 258 for the A-phase current estimation error, the sixth curve 260 for the B-phase current estimation error, and the seventh curve 262 for the C-phase current estimation error are shown.

[0063] exist Figures 8A to 8C The flowchart illustrates a method 300 for operating a motor driver configured to supply power to motor 26. In some embodiments, motor 26 is a PMSM. According to some embodiments of this disclosure, method 300 may be executed by ECU 30. As can be understood from this disclosure, the sequence of operations within this method is not limited to... Figures 8A to 8C The order of execution shown may be used, but may be performed in one or more different orders as applicable and in accordance with this disclosure.

[0064] Method 300 includes determining a first voltage command based on a torque command and an electric speed at step 302. Step 302 can be executed, for example, by processor 32 executing program instructions for implementing the start controller 103.

[0065] Method 300 also includes measuring the phase current in the motor at step 304. Step 304 can be performed by the phase current sensor 28.

[0066] Method 300 further includes determining an estimated motor current based on the phase current at step 306. Step 306 can be executed, for example, by processor 32 executing program instructions for implementing current estimator 130.

[0067] Method 300 further includes determining a second voltage command at step 308 based on the estimated motor current. Step 308 can be executed, for example, by processor 32 executing program instructions for implementing current regulator 106.

[0068] Method 300 further includes calculating the reconstructed α-axis current based on the phase current at step 310. Step 310 can be executed, for example, by processor 32 executing program instructions for implementing OSG 132.

[0069] Method 300 further includes, at step 312, determining the difference between the measured phase current and the reconstructed α-axis current as an estimation error. Step 312 can be executed, for example, by processor 32. Figure 4 The program instructions for step 202 of the process 200 shown are executed.

[0070] Method 300 further includes comparing the estimation error with an error threshold at step 314 to determine estimation conditions. Step 314 may be executed, for example, by processor 32. Figure 4 The program instructions for step 204 of the process 200 shown are executed.

[0071] Method 300 further includes selecting a first voltage command at step 316 based on an estimated condition to be used as the final voltage command. Step 316 may be executed, for example, by processor 32 executing program instructions for implementing the first current selector 120, and wherein the estimated condition control_mode is equal to zero.

[0072] Method 300 further includes selecting a second voltage command at step 318 based on an estimation condition to be used as the final voltage command. Step 318 may be executed, for example, by processor 32 executing program instructions for implementing the first current selector 120, wherein the estimation condition control mode has a non-zero value.

[0073] Method 300 further includes calculating the reconstructed β-axis current based on the reconstructed α-axis current at step 320. Step 320 can be executed, for example, by processor 32 executing program instructions for implementing OSG 132.

[0074] Method 300 further includes determining an estimated β-axis current based on the estimated motor current at step 322. Step 322 can be executed, for example, by processor 32 executing program instructions for implementing the dq-αβ transformer 142 of the current estimator 130.

[0075] Method 300 further includes, at step 324, determining the difference between the estimated β-axis current and the reconstructed β-axis current as a second estimation error. Step 324 can be executed, for example, by processor 32. Figure 4 The program instructions for step 206 of the process 200 shown are executed.

[0076] Method 300 further includes comparing the second estimation error with a second error threshold at step 326 to determine the second estimation condition. Step 326 may be executed, for example, by processor 32. Figure 4 The program instructions for step 208 of the process 200 shown are executed.

[0077] Method 300 further includes setting a final voltage command based on the first voltage command at step 328 based on a second estimation condition. Step 328 may be executed, for example, by processor 32 executing program instructions for implementing the first current selector 120, wherein the estimation condition control_mode is equal to zero.

[0078] Method 300 further includes setting a final voltage command based on a second voltage command at step 330 based on a second estimation condition. Step 330 may be executed, for example, by processor 32 executing program instructions for implementing the first current selector 120, wherein the estimation condition control mode has a non-zero value.

[0079] Method 300 further includes controlling the inverter to supply alternating current (AC) power to the motor based on a final voltage command at step 332. Step 332 can be executed, for example, by processor 32 executing program instructions for implementing the dq-abc transformer 108 and pulse width modulator 110 to generate gate driver signals 112 for controlling the switching devices of inverter 20.

[0080] The systems, methods, and / or processes and their steps described above can be implemented in hardware, software, or any combination of hardware and software suitable for a particular application. Hardware may include general-purpose computers and / or special-purpose computing devices, or specific aspects or components of specific computing devices. These processes may be implemented in one or more microprocessors, microcontrollers, embedded microcontrollers, programmable digital signal processors, or other programmable devices, as well as internal and / or external memory. These processes may also be implemented, or alternatively, in application-specific integrated circuits, programmable gate arrays, programmable array logic, or any other device or combination of devices that can be configured to process electronic signals. It will also be understood that one or more of the processes may be implemented as computer-executable code capable of executing on a machine-readable medium.

[0081] Computer executable code can be created using structured programming languages ​​such as C, object-oriented programming languages ​​such as C++, or any other high- or low-level programming languages ​​(including assembly language, hardware description languages, and database programming languages ​​and techniques). Computer executable code can be stored, compiled, or interpreted to run on one of the following: the aforementioned devices and processors, heterogeneous combinations of processor architectures, or combinations of different hardware and software, or any other machine capable of executing program instructions.

[0082] Therefore, in one aspect, each of the methods and combinations thereof described above can be implemented as computer-executable code that, when executed on one or more computing devices, performs the steps of the method. In another aspect, these methods can be implemented in a system that performs their steps and can be distributed across devices in various ways, or all functionality can be integrated into a dedicated, stand-alone device or other hardware. In yet another aspect, the means for performing the steps associated with the above-described processes can include any of the aforementioned hardware and / or software. All such enumerations and combinations are intended to fall within the scope of this disclosure.

[0083] The foregoing description is not intended to be exhaustive or limiting of this disclosure. Elements or features of a particular embodiment are generally not limited to that particular embodiment, but are interchangeable where applicable and can be used in selected embodiments, even if not specifically shown or described. Elements or features of a particular embodiment can also vary in many ways. Such variations should not be considered as departing from this disclosure, and all such modifications are intended to be included within the scope of this disclosure.

Claims

1. A method for operating a motor driver to supply power to a motor, comprising: The first voltage command is determined based on the torque command and the electric speed. Measure the phase current in the motor; The estimated motor current is determined based on the phase current; The second voltage command is determined based on the estimated motor current; The reconstructed α-axis current is calculated based on the phase current; The difference between the measured phase current and the reconstructed α-axis current is defined as the estimation error; The estimation error is compared with an error threshold to determine the estimation conditions; Based on the estimation conditions, one of the first voltage command or the second voltage command is selected as the final voltage command; as well as The inverter is controlled to supply AC power to the motor based on the final voltage command.

2. The method according to claim 1, wherein, The motor is a permanent magnet synchronous motor (PMSM).

3. The method according to claim 1, further comprising: The reconstructed β-axis current is calculated based on the reconstructed α-axis current; The estimated β-axis current is determined based on the estimated motor current; The difference between the estimated β-axis current and the reconstructed β-axis current is determined as the second estimation error; as well as The second estimation error is compared with a second error threshold to determine the second estimation condition, and Selecting either the first voltage command or the second voltage command as the final voltage command includes: further selecting either the first voltage command or the second voltage command based on the second estimation condition.

4. The method according to claim 1, wherein, Determining the estimated motor current also includes using a current observer to determine the estimated motor current based on the measured phase current.

5. The method according to claim 4, wherein, The current observer includes the Luenberger current observer (LCO).

6. The method according to claim 1, further comprising: Determine an estimated phase current for one or more other phases of the motor, different from the phase current; The second α-axis current is calculated based on the estimated phase current; as well as Based on the estimation conditions, one of the reconstructed α-axis current or the second α-axis current is selected as the selected α-axis current; Determining the estimated motor current includes: further determining the estimated motor current based on the selected α-axis current.

7. The method according to claim 1, wherein, Determining the first voltage command includes at least one of the following: calculating the first voltage command, or using a lookup table to determine the first voltage command.

8. The method according to claim 1, wherein, Determining the first voltage command includes calculating the first voltage command according to the following set of equations: ,in, It is the d-axis component of the first voltage command. It is the electric speed of the motor, L q It is a q-axis inductor. It is the torque command, It is an absolute quantity. It is a permanent magnet chain. It is the stator winding resistance, and It is the q-axis component of the first voltage command.

9. A motor drive system, comprising: An inverter having at least three pairs of switches that are operable to supply alternating current (AC) power to a motor; A current sensor configured to measure the phase current in the motor; The controller is configured to: The first voltage command is determined based on the torque command and the electric speed. The estimated motor current is determined based on the phase current; The second voltage command is determined based on the estimated motor current; The reconstructed α-axis current is calculated based on the measured phase current; The difference between the phase current and the reconstructed α-axis current is defined as the estimation error; The estimation error is compared with an error threshold to determine the estimation conditions; Based on the estimation conditions, one of the first voltage command or the second voltage command is selected as the final voltage command; as well as The inverter is controlled to supply AC power to the motor based on the final voltage command.

10. The motor drive system according to claim 9, wherein, The motor is a permanent magnet synchronous motor (PMSM).

11. The motor drive system according to claim 9, wherein, The controller is also configured to: The reconstructed β-axis current is calculated based on the reconstructed α-axis current; The estimated β-axis current is determined based on the estimated motor current; The difference between the estimated β-axis current and the reconstructed β-axis current is determined as the second estimation error; as well as The second estimation error is compared with a second error threshold to determine the second estimation condition; Selecting either the first voltage command or the second voltage command as the final voltage command includes: further selecting either the first voltage command or the second voltage command based on the second estimation condition.

12. The motor drive system according to claim 9, wherein, Determining the estimated motor current also includes using a current observer to determine the estimated motor current based on the measured phase current.

13. The motor drive system according to claim 12, wherein, The current observer includes the Luenberger current observer (LCO).

14. The motor drive system according to claim 9, wherein, The controller is also configured to: Determine an estimated phase current for one or more other phases of the motor, different from the phase current; The second α-axis current is calculated based on the estimated phase current; as well as Based on the estimation conditions, either the reconstructed α-axis current or the second α-axis current is selected as the selected α-axis current; as well as Determining the estimated motor current includes: further determining the estimated motor current based on the selected α-axis current.

15. The motor drive system according to claim 9, wherein, Determining the first voltage command includes calculating the first voltage command according to the following set of equations: ,in, It is the d-axis component of the first voltage command. It is the electric speed of the motor, L q It is a q-axis inductor. It is the torque command, It is an absolute quantity. It is a permanent magnet chain. It is the stator winding resistance, and It is the d-axis component of the first voltage command.

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