Method for controlling a permanent magnet synchronous motor

Abstract

The present invention provides a method for controlling a permanent magnet synchronous motor used in electric vehicles such as hybrid vehicles, fuel cell vehicles, and the like. The method for controlling the permanent magnet synchronous motor preferably comprises: detecting the absolute angular position of the permanent magnet synchronous motor; calculating the rotational speed of the permanent magnet synchronous motor based on the detected absolute angular position; detecting the voltage of a battery as a current source; and calculating a compensated rotational speed, for which a battery voltage fluctuation is compensated, from the rotational speed of the permanent magnet synchronous motor based on a torque command, the rotational speed of the permanent magnet synchronous motor, and the battery voltage.Generating a d-axis current command and a q-axis current command according to the torque command and the compensated speed using a predetermined current command characteristic map; converting three-phase currents flowing in the permanent magnet synchronous motor into a d-axis feedback current and a q-axis feedback current based on the detected absolute angular position; calculating a d-axis voltage command and a q-axis voltage command based on the d-axis current command, the q-axis current command, the d-axis feedback current, and the q-axis feedback current; converting the d-axis voltage command and the q-axis voltage command into three-phase voltage commands based on the detected absolute angular position; and controlling the operation of the permanent magnet synchronous motor based on the three-phase voltage commands.

Description

BACKGROUND(a) Technical field

[0001] The present application relates generally to a method for controlling a motor. In particular, it relates to a method for controlling a permanent magnet synchronous motor used in electric vehicles such as hybrid vehicles, fuel cell vehicles and the like. (b) State of the art

[0002] A permanent magnet synchronous motor (PMSM) is a high-performance and high-efficiency motor that is widely used in the fields of electric vehicles, including hybrid vehicles, fuel cell vehicles, and the like, as well as in other industries.

[0003] An internal permanent magnet synchronous motor (IPMSM) is specifically a synchronous motor with a permanent magnet embedded in a rotor iron core. The IPMSM exhibits excellent durability and drivability at high speeds, making it suitable for use as an electric vehicle motor.

[0004] For example, US patent 2008 0309264 A1 discloses a control device for controlling a rotating electric machine and a drive device for a vehicle, which includes an AC motor that rotates wheels and is driven by power supplied by a battery. The device comprises an AC motor that rotates wheels and is driven by power supplied by a battery, a unit for detecting instantaneous fluctuations provided in a motor control unit, which detects an instantaneous fluctuation in the current or voltage of the battery, and a current command operating unit that modifies a current command to be sent to the AC motor in such a way as to increase the internal loss of the AC motor.

[0005] As in Fig. As shown in Figure 1, according to a conventional method for controlling a permanent magnet synchronous motor, a current command generator 35 receives a torque command T. e* and a rotational speed ω rpm of the permanent magnet synchronous motor and generates a d-axis current command i d * and a q-axis current command i q * based on current command map data 36a and 36b.

[0006] When the current command generator 35 generates the d-axis and q-axis current commands i d * and i q * outputs, a current controller (not shown) generates d-axis and q-axis voltage commands V d * and V q * based on the d-axis and q-axis stream commands i d * and i q *. The permanent magnet synchronous motor is then driven by the generation of three-phase voltage commands V u *, V v * and V w * and controlled accordingly by pulse width modulation (PWM) and three-phase current control of an inverter.

[0007] Conventionally, however, a predetermined current command is generated in a suitable manner and the torque at the corresponding speed is generated accordingly according to the torque command and the motor speed based on a predetermined reference voltage map, without regard to the voltage of a battery as a current source for the motor, i.e., based on a map that is set to the lowest DC link voltage that meets the rated power of the motor.

[0008] Consequently, the battery voltage fluctuation cannot be reflected in real time, which reduces the voltage utilization of the inverter accordingly when the battery voltage increases during operation.

[0009] Particularly in electric vehicles such as hybrid vehicles, fuel cell vehicles and the like, generating the current command based on the characteristic map that is set to the reference voltage is disadvantageous with regard to the use of a voltage and a current, since the battery voltage during operation of a vehicle drive motor is correspondingly higher than the reference voltage at which the characteristic map is set.

[0010] Therefore, it is possible to perform linear interpolation using a current command map for each voltage step up to the maximum voltage generated while a vehicle is in motion. However, this requires a large data storage capacity as well as considerable time and effort.

[0011] Therefore, there is a need in the prior art for methods for controlling a permanent magnet synchronous motor used in electric vehicles.

[0012] The information disclosed above in this background section is intended only to improve the understanding of the background of the invention and may therefore contain information that does not constitute the prior art already known to a person skilled in the art in this country. OVERVIEW OF THE REGISTRATION

[0013] The object of the present invention is to provide a method for controlling a permanent magnet synchronous motor used in electric vehicles such as hybrid vehicles, fuel cell vehicles and the like, which can reflect a battery voltage fluctuation in real time.

[0014] The problem is solved by a method having the features of claim 1. Advantageous further developments are found in the dependent claims.

[0015] In certain preferred embodiments, the present invention provides a method for controlling a permanent magnet synchronous motor in which a battery voltage fluctuation is compensated in real time in order to improve the voltage utilization of a motor-inverter system and in turn to improve the fuel economy of the vehicle.

[0016] In a preferred embodiment, the present invention provides a method for controlling a permanent magnet synchronous motor, wherein the method preferably comprises detecting an absolute angular position of a permanent magnet synchronous motor; calculating a rotational speed of the permanent magnet synchronous motor based on the detected absolute angular position; detecting a voltage of a battery as a current source; calculating a compensated rotational speed, for which a battery voltage fluctuation is compensated, from the rotational speed of the permanent magnet synchronous motor based on a torque command, the rotational speed of the permanent magnet synchronous motor and the battery voltage; generating a d-axis current command and a q-axis current command according to the torque command and the compensated rotational speed using a predetermined current command characteristic map;Converting three-phase currents flowing into the permanent magnet synchronous motor into a d-axis feedback current and a q-axis feedback current based on the detected absolute angular position; calculating a corresponding d-axis voltage command and a q-axis voltage command based on the d-axis current command, the q-axis current command, the d-axis feedback current, and the q-axis feedback current; converting the d-axis voltage command and the q-axis voltage command into three-phase voltage commands based on the detected absolute angular position; and controlling the operation of the permanent magnet synchronous motor based on the three-phase voltage commands, wherein the step to calculate the compensated speed may preferably include determining whether the speed of the permanent magnet synchronous motor is greater than a predetermined weight application speed;The calculation of an operating load by applying a load to the speed and torque command if the speed of the permanent magnet synchronous motor is greater than the load application speed; and the calculation of the compensated speed, for which a battery voltage fluctuation is compensated, from the speed of the permanent magnet synchronous motor based on the operating load and a reference voltage used when the current command map is set. The operating load is calculated using the following equation E1 based on a predetermined speed load and a torque command load: KN=Kω(ωrpm−ωo)+KT|Te*| where K N which represents the operating load, K ω The speed load is represented by ω. rpm ω0 represents the motor speed, ω0 the load application starting speed, K T represents the torque load and T e * represents the torque command.

[0017] In another preferred embodiment, the operating load is zero if the speed of the permanent magnet synchronous motor is correspondingly lower than the load application speed.

[0018] In yet another preferred embodiment, the step for calculating the compensated speed can further comprise determining whether the battery voltage is greater than a predetermined compensation start voltage, wherein the compensated speed can be calculated accordingly and used as an input variable of the current command map data if the battery voltage is greater than the compensation start voltage, and if the battery voltage is less than the compensation start voltage, the speed of the permanent magnet synchronous motor can be used as an input variable of the current command map data instead of the compensated speed.

[0019] In yet another preferred embodiment, the compensated speed can be calculated using a motor speed normalization formula, in which the operating load, the battery voltage and the speed of the permanent magnet synchronous motor are used as input variables.

[0020] In another preferred embodiment, the compensated speed can be a normalized motor speed, which can be calculated using the motor speed normalization formula, represented by the following equation E2: ωrpm.Nom=[1+F{(1+KN)VDC,MAPVDC−1}]ωrpm where ω rpm, Nom which represents the normalized engine speed, K N represents the operating load, V DC,MAP The reference voltage is used when setting the characteristic map, V DC represents the battery voltage and F equals 1 (V DC ≥V0) or 0 (V DC < V0), in which V DCV0 represents the battery voltage and V0 represents the compensation start voltage.

[0021] Further embodiments and preferred embodiments of the invention are explained below.

[0022] It should be noted that the term "vehicle" or "vehicle-" or other equivalent terms as used herein include motor vehicles in general, such as passenger cars including sports utility vehicles (SUVs), buses, trucks, various utility vehicles, watercraft including a variety of boats and ships, aircraft and the like, and hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other vehicles using alternative fuels (for example, fuel derived from sources other than petroleum). As referenced herein, a hybrid vehicle is a vehicle that has two or more sources of propulsion, such as both gasoline-powered and electric-powered vehicles.

[0023] The above features and advantages of the present invention will be evident or explained in detail in the accompanying drawings, which are included and form part of the description, and in the present detailed description, which together serve to explain the principles of the present invention by means of examples. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above and further features of the present invention will now be described in detail with reference to certain exemplary embodiments shown in the accompanying drawings, which below serve only for illustration and are therefore not limiting to the present invention, and wherein: Fig. Figure 1 shows a schematic diagram representing a conventional current command generator for generating current commands. Fig. Figure 2 shows a schematic diagram illustrating a system for controlling a permanent magnet synchronous motor according to an exemplary embodiment of the present invention. Fig. Figure 3 shows a schematic diagram representing a current command generator for generating current commands according to an exemplary embodiment of the present invention. Fig. Figure 4 shows a flowchart illustrating a method for controlling a permanent magnet synchronous motor according to an exemplary embodiment of the present invention.

[0025] The reference symbols shown in the drawings include a reference to the following elements as further explained below: 11 permanent magnet synchronous motor 13 PWM inverters 15 Spatial vector pulse duration modulation algorithm module 17 Position detector 21 Battery 19 Current detector 23 Voltage detector 31 Angular velocity calculating device 33 Three-phase / dq coordinate converters 35 Current command generator 35a Voltage fluctuation compensator 37 current regulators 39 dq / three-phase coordinate converters

[0026] It should be noted that the accompanying drawings are not necessarily to scale and represent a somewhat simplified depiction of various preferred features that illustrate the principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, installation locations, and shapes, are partly determined by the application specifically provided for this purpose and the working environment.

[0027] In the figures, the reference numerals throughout the individual figures of the drawings refer to the same or equivalent parts of the present invention. DETAILED DESCRIPTION

[0028] As described herein, the present invention is characterized by a method for controlling a permanent magnet synchronous motor, wherein the method comprises detecting an absolute angular position of a permanent magnet synchronous motor, calculating a rotational speed of the permanent magnet synchronous motor based on the detected absolute angular position, detecting a voltage of a battery as a current source, calculating a compensated rotational speed, wherein a battery voltage fluctuation is compensated from the compensated rotational speed, generating a d-axis current command and a q-axis current command corresponding to the torque command and the compensated rotational speed using a predetermined current command characteristic map, and converting three-phase currents flowing into the permanent magnet synchronous motor into a d-axis feedback current and a q-axis feedback current based on the detected absolute angular position.Calculating a d-axis voltage command and a q-axis voltage command based on the d-axis current command, the q-axis current command, the d-axis feedback current, and the q-axis feedback current; converting the d-axis voltage command and the q-axis voltage command into three-phase voltage commands based on the detected absolute angular position; and controlling the operation of the permanent magnet synchronous motor based on the three-phase voltage commands.

[0029] In one embodiment, the compensated speed is calculated from the speed of the permanent magnet synchronous motor based on a torque command, the speed of the permanent magnet synchronous motor and the battery voltage.

[0030] The various embodiments of the present invention will now be described in detail, with examples illustrated in the accompanying drawings and described below. Although the invention is described in connection with exemplary embodiments, it should be noted that this description is not intended to limit the invention to those exemplary embodiments. On the contrary, the invention is intended to cover not only the exemplary embodiments but also a wide variety of alternatives, modifications, equivalents, and further embodiments that may be included within the spirit and scope of the invention as defined in the accompanying claims.

[0031] The symbols used in the description and drawings are defined as follows: T e * Torque command Vq * q-axis voltage command i q * q-axis current command V e * d-axis tension command i d * d-axis current command i d d-axis feedback current i q q-axis feedback current V u * V v *, V w * Three-phase voltage commands D u ,D v ,D w Operating phases for switching control signals of the inverter V DC Battery voltage (DC link voltage) i us , i vs , i ws Three-phase currents ω rpm Engine speed ω0 Load application starting speed ω rpm, Nom normalized engine speed K ω Speed ​​load K N Operating load K T Torque command load V0 compensation start voltage F Voltage fluctuation flag V DC,MAP Characteristic map setting reference voltage (DC voltage during mapping)

[0032] According to preferred embodiments, the present invention provides a system and a method for controlling a permanent magnet synchronous motor which can reflect a voltage fluctuation of a battery as a current source of the motor during operation in real time using an existing reference voltage characteristic map, i.e., a characteristic map that is set at a predetermined voltage when a current command is generated according to a motor speed and a required torque (torque command).

[0033] According to certain preferred embodiments and such as in Fig. Figure 2 shows reference numeral 11 as a permanent magnet synchronous motor. In further preferred embodiments, the permanent magnet synchronous motor can, for example, be a synchronous motor with an internal permanent magnet.

[0034] In further preferred embodiments, reference numeral 21 denotes a battery (high-voltage battery) used as a power source for the permanent magnet synchronous motor 11. The battery 21 preferably supplies drive power to the motor in an electric vehicle (EV) mode or a hybrid electric vehicle (HEV) mode and stores the energy generated by the motor, which operates in a generation mode, in a regenerative braking (RB) mode. According to further preferred embodiments, in a fuel cell vehicle (with a fuel cell-battery hybrid system), the battery 21, together with a fuel cell stack (not shown), is provided as a main power source and serves as an auxiliary power source to supply the drive power to the motor.

[0035] According to certain exemplary embodiments, reference numeral 13 denotes a PWM inverter which supplies a three-phase alternating current to the permanent magnet synchronous motor 11. The PWM inverter 13 preferably controls a motor application voltage (inverter output voltage) by pulse width modulation (PWM) in order to control the three-phase currents i supplied to the motor 11. us , i vs and i ws to regulate. In further preferred embodiments, the PWM inverter 13 preferably comprises a power module (not shown) formed from a semiconductor switch (e.g. IGBT) capable of high-speed switching and a diode forming a current loop during energy generation.

[0036] Preferably, the PWM control method controls the voltage (or current) by appropriately modifying a switching pulse to switch the semiconductor switch in the inverter and preferably comprises a triangular wave comparison PWM method and a space vector PWM method. According to certain exemplary embodiments, Fig. 2. An example of the space vector PWM method. PWM and the three-phase control of the inverter are well known to experts, and therefore a detailed description is omitted.

[0037] According to other preferred embodiments, the control system according to the present invention comprises a position detector 17 for detecting an absolute angular position θ of a motor. Preferably, the absolute angular position θ means any angular position in which the current is supplied to the permanent magnet synchronous motor 11. According to certain preferred embodiments, the position detector 17 can be a rotary encoder.

[0038] In preferred embodiments, reference numeral 19 designates a current detector for detecting each of the phase currents i flowing into the permanent magnet synchronous motor 11. us , i vs and i ws by the output voltage of the PWM inverter 13. Preferably, the phase currents detected by the current detector can be used to control the inverter.

[0039] According to further preferred embodiments, the control system according to the present invention monitors the battery voltage fluctuation and reflects it accordingly when controlling the motor in order to compensate for the battery voltage fluctuation in real time. Preferably, a DC link voltage V is used. DC The inverter's voltage is detected and used as a voltage value to monitor battery voltage fluctuations.

[0040] Accordingly, the control system according to the present invention preferably comprises a voltage detector 23 for detecting the DC link voltage V DCthan the battery voltage. Preferably, the voltage detector can be configured to detect the voltage at both ends of a DC-link capacitor (not shown), which absorbs the high-frequency ripple component of the DC voltage generated by the operation of the inverter and smooths the DC voltage. According to further preferred embodiments, it is preferred that a characteristic curve, which at the lowest DC-link voltage V DC,MAP The voltage is set to meet the motor's rated power outputs, as reference voltage characteristics 36a and 36b (shown in Fig. 3) is used, the DC link voltage V DC to detect by the voltage detector 23 and then the detected DC link voltage V DC to use in order to compensate for the voltage fluctuation accordingly.

[0041] According to further preferred embodiments of the present invention, the control system preferably also comprises an angular velocity calculating device 31 for calculating a motor speed ω. rpm based on the signal from the position detector 17; a three-phase / dq coordinate converter for calculating a d-axis feedback current i d and a q-axis feedback current i q based on the signals from the position detector 17 and the current detector 19; a current command generator 35 for generating a corresponding d-axis current command i d * and a q-axis current command i q *, for which the voltage fluctuation is compensated, based on a torque command T provided by a higher-level controller e *, the motor speed ω entered by the angular velocity calculating device 31 rpmand the signal from the voltage detector 23; a current controller 37 for the corresponding calculation of a d-axis voltage command V d * or a q-axis voltage command V q *; and a dq / three-phase coordinate converter 39 for calculating three-phase voltage commands V u *, V v * and V w , based on the signal from position detector 17 and the d-axis voltage command V d * and the q-axis voltage command V q *, which are entered by the current controller 37.

[0042] The angular velocity calculating device 31 preferably receives the angular position θ measured by the position detector 17, i.e., rotary encoder, and calculates the motor speed ω. rpm based on the detected angular position θ. The angular velocity calculating device can, for example, preferably include a differentiator.

[0043] According to further preferred embodiments, the three-phase / dq coordinate converter 33 receives the angular position θ detected by the position detector 17 and the phase currents i detected by the current detector 19. us , i vs , and I ws and converts the three-phase currents i us , i vs , and I ws into the d-axis feedback current and q-axis feedback current using the angular position θ.

[0044] Furthermore, the current command generator 35 of the present invention receives the torque command T provided by the higher-level control system. e *, the motor speed ω calculated by the angular velocity calculator rpm and the DC link voltage V detected by the voltage detector 23 DC and accordingly generates the d-axis current command i d * and the q-axis current command i q*, for which the voltage fluctuation is compensated accordingly, using predetermined current command data based on the torque command T e *, the engine speed ω rpm and the DC link voltage V DC The higher-level control can be a typical hybrid control unit (HCU), which generates and outputs the torque command accordingly.

[0045] The predetermined current command data can preferably be the existing current command data with the torque command and the rotational speed as input variables. The predetermined current command data preferably includes predetermined d-axis current command data for generating the d-axis current command i. d * and predetermined q-axis current command data to generate the q-axis current command i q *, which correspond to the torque command and the speed.

[0046] The d-axis current command data and the q-axis current command data are preferably characteristic map data for the corresponding calculation of the current commands from the torque command, and the existing d-axis current command characteristic map 36a ( Fig. 3) and the existing q-axis current command map 36b ( Fig. 3), which are generated at a predetermined reference voltage, can be used as they are.

[0047] According to further embodiments of the present invention, the predetermined d-axis current command map 36a comprises a plurality of optimal d-axis current command values ​​mapped with reference to a plurality of torques or a plurality of rotational speeds, and the predetermined q-axis current command map 36b preferably comprises a plurality of optimal q-axis current command values ​​mapped with reference to a plurality of torques or a plurality of rotational speeds.

[0048] According to other preferred embodiments, the d-axis current command map and the q-axis current command map can be set using data obtained from a previous test. For example, according to certain exemplary embodiments, the d-axis current command map and the q-axis current command map can be set by calculating optimal d-axis current commands and q-axis current commands for each torque and speed using a bidirectional test bench (dynamometer) and then mapping these values.

[0049] To perform the voltage fluctuation compensation in the manner described above, the current command generator 35 of the present invention preferably further comprises a voltage fluctuation compensator 35a for calculating a compensated motor speed ω rpmbased on the torque command T provided by the higher-level controller e *, the motor speed ω calculated by the angular velocity calculator rpm and the DC link voltage (battery voltage) V detected by the voltage detector 23 DC (see Fig. 3).

[0050] In detail, the current command generator 35 according to the present invention generates the d-axis and q-axis current commands i d * and i q * using the d-axis and q-axis current command maps 36a and 36d and also receives the DC link voltage V DC , which is detected in real time to compensate for the battery voltage fluctuation. The voltage fluctuation compensator 35a preferably calculates the compensated motor speed ω. rpm,Nom using the torque command T e *, the detected engine speed ω rpm and the DC link voltage (battery voltage) VDC Preferably, the compensated motor speed ω rpm,Nom (hereinafter referred to as "compensated speed") and the torque command T e * used as input variables of the d-axis current command characteristic map 36a and the q-axis current command characteristic map 36b for the corresponding generation of the current commands.

[0051] Consequently, according to preferred embodiments of the present invention, since the d-axis current command i d * and the q-axis current command i q * by the d-axis current command map 36a and the q-axis current command map 36b based on the torque command T e * and the compensated rotational speed ω rpm,Nom Each of the generated current commands is generated according to the current command for which the voltage fluctuation is compensated.

[0052] The process for calculating the compensated speed, i.e., the process for compensating the voltage fluctuation with respect to the motor speed ω. rpm , which is carried out by the voltage fluctuation compensator 35a of the current command generator 35 using the DC link voltage, is described with reference to Fig. 3 and Fig. 4 described.

[0053] According to further preferred embodiments of the present invention, the current controller 37 receives the d-axis current command i d * and the q-axis current command i q *, which are output by the current command generator 35, and the d-axis feedback current i d and the q-axis feedback current i q , which are output by the three-phase / dq converter 33, and generates the d-axis voltage command V d * and the q-axis voltage command V q* based on the same. Preferably, the rotational speed ω output by the angular velocity calculating device 31 can be rpm furthermore, it can be used to execute the d-axis current command i d * and the q-axis current command i q * to calculate.

[0054] According to other preferred embodiments, the dq / three-phase coordinate converter 39 converts the d-axis voltage command V d * and the q-axis voltage command V q *, which are entered by the current controller 37, into the three-phase voltage commands V u *, V v * and V w using the absolute angular position θ um, which is input by the position detector 17.

[0055] As a result, the three-phase voltage commands V u *, V v * and V w , which are output by the dq / three-phase coordinate converter 39, are fed into a space vector PWM algorithm module to determine operating phases D u,D v and D w to generate switching control signals, and the PWM inverter 13 controls the three-phase currents supplied to the permanent magnet synchronous motor 11 based on the operating modes.

[0056] The coordinate conversion process of each coordinate converter, the generation of operating modes using space vector pulse width modulation and the three-phase current control, as well as the voltage command calculation process described above, are well known in the prior art relating to the present invention, and a detailed description thereof is omitted.

[0057] According to further embodiments, the process for calculating the compensated speed, which is carried out by the voltage fluctuation compensator 35a of the current command generator, is described with reference to Fig. 3 and Fig. 4 described.

[0058] Firstly, with reference to Fig. 3 the current command generator 35 preferably the voltage fluctuation compensator 35a, which generates the torque command T e *, the engine speed ω rpm and the battery voltage V DC receives and calculates the motor speed accordingly, for which the voltage fluctuation is compensated, that is, the compensated speed ω. rpm,Nom based on the same.

[0059] In order to reflect the battery voltage fluctuation during operation accordingly, according to preferred embodiments of the present invention, the voltage fluctuation compensator 35a of the current command generator 35 compensates the voltage fluctuation with respect to the input quantities of the current command characteristic map 36a and 36b using the battery voltage (DC link voltage) V detected by the voltage detector 23. DCThe voltage fluctuation compensator 35a can preferably be configured to compensate for the voltage fluctuation with respect to the motor speed ω. rpm to compensate for the input variable of the current characteristic map data accordingly.

[0060] In particularly preferred embodiments, a motor speed normalization method is used in accordance with the voltage fluctuation described in the present invention, and the battery voltage fluctuation is compensated by a motor speed normalization method in which a load is applied to each motor speed, each torque command, and each battery voltage. As described herein, the battery voltage fluctuation in the present invention refers to the fluctuation of the battery voltage caused during operation based on the DC voltage during mapping, that is, a reference voltage at which the current command map is set. Preferably, when setting the current command map, the reference voltage (hereinafter referred to as the "map setting reference voltage") is generally determined to be the lowest DC link voltage that satisfies the rated power of the motor.

[0061] According to certain preferred embodiments and with reference to Fig. 4. For example, parameter values ​​should be predetermined that are required for the compensated speed calculation process carried out by the voltage fluctuation compensator.

[0062] According to the present invention, the parameter values ​​required for the logic include a load application starting speed ω0, a speed load K ω , a torque command load K T and a compensation start voltage V0, which is obtained and stored from a previous test under different conditions.

[0063] In a state where the parameter values ​​are predetermined accordingly, the motor speed ω detected during the operation of the permanent magnet synchronous motor will therefore be rpm The instantaneous DC voltage V is entered accordingly by the angular velocity calculating device. DCis entered by the voltage detector and the torque command T e * is entered by the higher-level controller (S11). Preferably, it is determined whether the motor speed ω rpm The load application requires (S12).

[0064] Therefore, the detected motor speed ω rpm compared with the load application starting speed ω0 to determine if the motor speed ω rpm corresponds to the load application speed. If the motor speed ω rpm If the load application starting speed ω0 is greater than the motor speed ω, it is determined that the motor speed ω rpm corresponds to the load application speed, and the operating load K N is achieved accordingly by applying the appropriate loads K ω and K T calculated with reference to the rotational speed and the torque command from the following equation 1 (S13). KN=Kω(ωrpm−ωo)+KT|Te*|

[0065] If the engine speed ω rpmless than the load application starting speed ω0, that is, if it is determined that the motor speed ω rpm If the load application condition does not correspond, the operating load is preferably zero (K). N = 0) (S13').

[0066] Preferably, with regard to operating performance, it is undesirable for the load to be applied at every motor speed. Therefore, an optimal limit at which the load should be applied is determined experimentally, taking into account the operating performance and the improvement of the voltage utilization caused by voltage fluctuations. Preferably, the optimal limit is set to the load application starting speed ω0, so that the load can only be applied when it corresponds to the load application condition.

[0067] As soon as the operating load K N The compensated rotational speed ω is obtained in the manner described above. rpm,Nom, for which the battery voltage fluctuation is compensated, from the engine speed ω rpm using battery voltage V DC and the map setting reference voltage V DC,MAP as well as the operating load K N calculated.

[0068] In a further exemplary embodiment of the present invention, it is determined accordingly whether voltage fluctuation compensation is required based on the battery voltage, that is, the DC link voltage V detected by the voltage detector. DC (S14). If it is determined that the DC link voltage V DC The voltage fluctuation compensation required is the compensated rotational speed ω. rpm,Nom calculated according to the voltage fluctuation from a predetermined equation (S15 and S16).

[0069] According to further exemplary embodiments, the DC link voltage V is specified in detail. DCThe DC link voltage is compared to the predetermined compensation start voltage V0 to determine whether voltage fluctuation compensation is required. DC If the compensation start voltage V0 is greater than the compensation start voltage, it is preferably determined that voltage fluctuation compensation is required (S15) and the compensated speed ω rpm,Nom The voltage fluctuations are obtained from a predetermined equation (S16).

[0070] For example, in exemplary embodiments, the equation described above can be a motor speed normalization formula according to the voltage fluctuation, and the motor speed normalization formula can be represented by the following equation 2: ωrpm.Nom=[1+F{(1+KN)VDC,MAPVDC−1}]ωrpm where V DC,MAP represents the map setting reference voltage.

[0071] In equation 2 above, F represents a flag in the logic, indicating whether or not compensation is applied. If the DC link voltage V DC The voltage fluctuation compensation required corresponds to F 1 (F = 1) (S15), whereas if the DC link voltage V DC Voltage fluctuation compensation is not needed, F zero corresponds to (F = 0) (S15').

[0072] Equation 2 is used to calculate the normalized motor speed ω. rpm using the operating load K calculated from equation 1 N , the detected DC link voltage V DC and the engine speed ω rpm to be calculated as input variables. The normalized motor speed ω calculated from equation 2. rpm,Nom This corresponds to the compensated speed, which is entered into the current command map. The compensated speed corresponds to a speed value for which the voltage fluctuation is compensated, derived from the motor speed ω. rpm, which is entered by the angular velocity calculating device.

[0073] If the DC link voltage V DC However, if F is lower than the compensation start voltage V0, then F corresponds to zero (F = 0) in equation 2. Consequently, the instantaneous motor speed ω rpm used as an input variable of the current command map data instead of the compensated speed.

[0074] According to further embodiments, the compensation start voltage V0 is obtained by obtaining an optimal limit voltage to determine whether the compensation from the previous test is needed, taking into account the improvement in voltage utilization caused by the voltage fluctuation compensation.

[0075] According to preferred embodiments of the present invention, the compensated motor speed ω is therefore rpm,Nom, i.e., the compensated rotational speed as an input variable of the d-axis current command map 36a and the q-axis current command map 36b together with the torque command T e * used to obtain the d-axis and q-axis commands (see Fig. 3) Preferably, when the d-axis and q-axis current commands, in which the voltage fluctuation is reflected accordingly, are obtained, they are used to control the permanent magnet synchronous motor.

[0076] As described herein, according to the method for controlling the permanent magnet synchronous motor of the present invention, the battery voltage fluctuation can be reflected in real time when controlling the permanent magnet synchronous motor, which improves the voltage utilization of the motor-inverter system and in turn improves vehicle performance (such as energy efficiency, fuel saving and the like).

[0077] Furthermore, it is possible to ensure the stability of current control in the high-voltage and high-speed range, reduce the amount of data required to generate current commands and the data storage, and save personnel and time required for data setup and data verification, compared to conventional methods for performing linear interpolation using the current command map for each voltage step up to the maximum voltage.

Claims

[1] Method for controlling a permanent magnet synchronous motor, wherein the method comprises: Detecting the absolute angular position of a permanent magnet synchronous motor; Calculating the rotational speed of the permanent magnet synchronous motor based on the detected absolute angular position; Detecting the voltage of a battery as a power source; Calculating a compensated speed, for which a battery voltage fluctuation is compensated, from the speed of the permanent magnet synchronous motor based on a torque command, the speed of the permanent magnet synchronous motor and the battery voltage; Generating a d-axis current command and a q-axis current command according to the torque command and the compensated speed using a predetermined current command map; Converting three-phase currents flowing into the permanent magnet synchronous motor into a d-axis feedback current and a q-axis feedback current based on the detected absolute angular position; Calculating a d-axis voltage command and a q-axis voltage command based on the d-axis current command, the q-axis current command, the d-axis feedback current, and the q-axis feedback current; Converting the d-axis voltage command and the q-axis voltage command into three-phase voltage commands based on the detected absolute angular position; and Controlling the operation of the permanent magnet synchronous motor based on the three-phase voltage commands, where calculating the compensated speed, for which a battery voltage fluctuation is compensated from the speed of the permanent magnet synchronous motor, includes: Determine whether the speed of the permanent magnet synchronous motor is greater than a predetermined load application speed; Calculating an operating load by applying a load to the speed and torque command if the speed of the permanent magnet synchronous motor is greater than the load application speed; Calculating the compensated speed, for which a battery voltage fluctuation is compensated, from the speed of the permanent magnet synchronous motor based on the operating load and a reference voltage that is used when the current command map is set. where the operating load is calculated by the following equation E1 based on a predetermined speed load and a torque command load: KN=Kω(ωrpm−ωo)+KT|Te*| where K N which represents the operating load, K ω The speed load is represented by ω. rpm ω0 represents the motor speed, ω0 the load application starting speed, KT represents the torque load and T e * represents the torque command. [2] Method according to claim 1, wherein the operating load is zero if the speed of the permanent magnet synchronous motor is lower than the load application speed. [3] Method according to claim 1, wherein the calculation of the compensated speed further comprises determining whether the battery voltage is greater than a predetermined compensation start voltage, wherein, if the battery voltage is greater than the compensation start voltage, the compensated speed is calculated and used as an input variable of the current command map data, and if the battery voltage is lower than the compensation start voltage, the speed of the permanent magnet synchronous motor is used as an input variable of the current command map data instead of the compensated speed. [4] Method according to claim 3, wherein the compensated speed is calculated by a motor speed normalization formula in which the operating load, the battery voltage and the speed of the permanent magnet synchronous motor are used as input variables. [5] Method according to claim 5, wherein the compensated speed is a normalized speed calculated by the motor speed normalization formula represented by the following equation E2: ωrpm.Nom=[1+F{(1+KN)VDC,MAPVDC−1}]ωrpm where ω rpm,Nom which represents the normalized engine speed, K N represents the operating load, V DC,MAP The reference voltage is used when setting the characteristic map, V DC represents the battery voltage and F equals 1 (V DC >V0) or 0 (V DC < V0), in which V DC V0 represents the battery voltage and V0 represents the compensation start voltage.

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