Method for preventing step-out phenomenon of rotor of motor at low temperature and device therefor

Abstract

Disclosed, in one embodiment of the present invention, is a method for preventing a step-out phenomenon of a rotor of a motor at a low temperature, the method comprising the steps of: by driving a stopped motor by a first mode, increasing the speed of the motor up to a first RPM value at which a first back electromotive force starts to be measured; monitoring whether the speed of the motor is stably maintained at the first RPM value; as a result of the monitoring, if the speed of the motor is maintained at the first RPM value, processing the first back electromotive force, thereby calculating a first back electromotive force processed value and a second back electromotive force processed value; estimating the magnitude of a harmonic component of the first back electromotive force by using a result of comparing the calculated first back electromotive force processed value and second back electromotive force processed value; determining whether the motor is in a normal rotation state by analyzing the estimated magnitude of the harmonic component; if the motor is in the normal rotation state, increasing the speed of the motor up to a second RPM value; and, in the process of increasing the speed up to the second RPM value, if the motor is maintained in the normal rotation state, controlling so that the speed of the motor is further increased up to a third RPM value so as to switch the motor to a second mode.

Description

Method for preventing rotor slippage of a motor at low temperatures and device therefor

[0001] The present invention relates to a method for preventing a synchronizing phenomenon that may occur in a rotor of a motor, and more specifically, to a method and device for preventing a synchronizing phenomenon of a rotor that is highly likely to occur when a motor operates at low temperatures.

[0002] Pumps used in existing vehicles are physically connected to the engine's rotating shaft and are designed to rotate immediately when the engine starts, ensuring rapid rotational response. Recently, these pumps are being replaced by Permanent Magnet Synchronous Motors (PMSM) motors, and Hall sensors and encoders are being utilized to control PMSM motors.

[0003] However, motors that include hall sensors or encoders have a high unit price, which increases the overall cost. To solve this problem, research on sensor-less type motors is actively being conducted.

[0004] FIG. 1a and FIG. 1b are drawings for explaining cogging torque according to the position of the rotor in a sensor-less type motor.

[0005] Fig. 1a shows a rotor in which six types of wires are wound around a magnet, and the wires may be referred to as a, b, c, d, e, and f, respectively. The six types of wires in Fig. 1b each have different characteristics in terms of changes in cogging torque according to angle.

[0006] Sensorless type motors have the characteristic of going through a 'magnet arrangement process' for initial driving. Sensorless type motors fix the magnets at the desired position through magnet alignment, and then apply a voltage vector (voltage pulse) to create the minimum BEMF voltage (Back EMF Voltage) for sensorless control. Then, based on the generated BEMF voltage, the motor estimates the angle and rotates based on the estimated value.

[0007] The above method fails to meet the pump's specifications. Specifically, the pump must operate at 2,600 rpm and achieve a response time of 0.3 to 0.6 seconds. However, sensorless motors like the one described above require a magnetic alignment time of at least 1 second, making them unable to meet the pump's demanding, rapid response.

[0008] To solve this problem, the magnet alignment process can be omitted through an initial position estimation process that takes about 0.01 seconds. However, the conventional initial position estimation process has limitations in that it operates only for a motor consisting of only 6 sectors, causes noise in the motor by applying high-frequency current, or causes the rotor to move unintentionally during position estimation, resulting in an incorrect position being determined. Therefore, an improved method is needed.

[0009] Meanwhile, motors using permanent magnets (IPM motors) can be applied to various vehicle oil pumps, fuel pumps, and water pumps. Among the methods for implementing pumps based on IPM motors, the latest trend is to implement a sensorless type motor that removes various sensors. Among the methods for controlling sensorless type motors, one method is to utilize back-EMF.

[0010] Back electromotive force is an induced electromotive force generated when the motor is operated and the motor rotor rotates, and it is not generated before the rotor rotates. When operating an IPM motor as a sensorless type motor, a minimum back electromotive force must be observed in order to determine the position of the north pole of the magnet, so a forced start (open-loop) must inevitably be performed first. That is, during the forced start process, the motor speed must be increased to a level where the minimum back electromotive force can be stably measured. If the back electromotive force is stably observed above a preset value in the forced start mode, the motor can be switched to sensorless mode.

[0011] Figure 2 is a diagram schematically showing the positions where inductance is maximum and minimum depending on the rotor position in a sensor-less type motor.

[0012] Referring to Fig. 2, it can be seen that the sensor-less type motor is divided into a total of 6 sectors, and for convenience of explanation, the base sector is assumed to be sector 0.

[0013] In Fig. 2, when the N pole of the permanent magnet coincides with sector 0, the reference line of the horizontal N pole and S pole is the point where the inductance of the rotor is minimum, and the Q-axis, where the vertical line to the reference lines of the N pole and S pole is located, is the point where the inductance is maximum.

[0014] In addition, in Fig. 2, when the N pole of the permanent magnet coincides with the reference line drawn at an angle of 15 degrees added to sector 0, it can be seen that the reference line of the N pole and S pole that is tilted by 15 degrees is the point where the inductance of the rotor is minimum, and the Q-axis where the perpendicular to the reference lines of the N pole and S pole is located is the point where the inductance is maximum.

[0015] Motor-based pumps tend to experience very high pipeline resistance or very poor ripple characteristics in cryogenic conditions due to the increased viscosity of the refrigerant or oil. In such cryogenic conditions, it is difficult to control the motor speed consistently during the initial open-loop start-up, making it difficult to secure a stable back-EMF value above a certain level. This increases the possibility of a step-out phenomenon when switching to sensorless mode. Furthermore, in such cryogenic conditions, the motor may start too quickly during the mode switch, potentially causing the motor to stall due to insufficient torque as soon as it switches to sensorless mode.

[0016] Therefore, in implementing an in-vehicle pump based on an IPM motor in an extremely low temperature environment, a methodology is needed to prevent the motor from losing its synchronism as described above or the motor from stopping immediately after switching to sensor-read mode.

[0017] The technical problem to be solved by the present invention is to provide a method for preventing the motor from losing its synchronism at low temperatures and a device for implementing the method.

[0018] According to one embodiment of the present invention for solving the above technical problem, a method comprises: starting a stopped motor in a first mode, thereby increasing the speed of the motor to a first RPM value at which a first counter electromotive force starts to be measured; monitoring whether the speed of the motor is stably maintained at the first RPM value; if the monitoring result shows that the speed of the motor is maintained at the first RPM value, processing the first counter electromotive force to produce a first counter electromotive force processed value and a second counter electromotive force processed value; estimating the magnitude of a harmonic component of the first counter electromotive force using a result of comparing the produced first counter electromotive force processed value and the second counter electromotive force processed value; determining whether the motor is in a normal rotation state by analyzing the magnitude of the estimated harmonic component; if the motor is in a normal rotation state, increasing the speed of the motor to a second RPM value; And in the process of increasing to the second RPM value, if the motor maintains a normal rotation state, a step of controlling the motor to further increase the speed of the motor to a third RPM value and switch the motor to the second mode is included.

[0019] According to another embodiment of the present invention for solving the above technical problem, a device is provided as a device for preventing a rotor of a motor from being out of sync at low temperatures, comprising: a memory storing at least one program; And a processor that performs an operation by executing at least one program; wherein the processor starts the stopped motor in a first mode, thereby increasing the speed of the motor to a first RPM value at which a first counter electromotive force starts to be measured, monitors whether the speed of the motor is stably maintained at the first RPM value, and if the speed of the motor is maintained at the first RPM value as a result of the monitoring, processes the first counter electromotive force to calculate a first counter electromotive force processed value and a second counter electromotive force processed value, estimates the magnitude of a harmonic component of the first counter electromotive force using a result of comparing the calculated first counter electromotive force processed value and the second counter electromotive force processed value, and determines whether the motor is in a normal rotation state by analyzing the magnitude of the estimated harmonic component, and if the motor is in a normal rotation state, increases the speed of the motor to a second RPM value, and if the motor maintains a normal rotation state in the process of increasing to the second RPM value, further increases the speed of the motor to a third RPM value to operate the motor in the second mode. You can control it to switch.

[0020] One embodiment of the present invention can provide a computer-readable recording medium storing a program for executing the above method.

[0021] According to the present invention, when using a sensor-less type motor at low temperatures, the phenomenon of motor loss can be prevented.

[0022] In addition, according to the present invention, when using a sensor-less type motor at low temperatures, the phenomenon of the motor stopping when switching from open loop mode to forced start mode can be prevented.

[0023] FIG. 1a and FIG. 1b are drawings for explaining cogging torque according to the position of the rotor in a sensor-less type motor.

[0024] Figure 2 is a diagram schematically showing the positions where inductance is maximum and minimum depending on the rotor position in a sensor-less type motor.

[0025] FIG. 3 is a flowchart showing an example of scripts of a loss prevention control algorithm installed in a low-temperature loss prevention device according to the present invention.

[0026] Figure 4 is a flowchart for explaining an example of the scripts of the anti-slip control algorithm described in Figure 3.

[0027] FIG. 5 is a flowchart illustrating another example of the anti-slip control algorithm described in FIGS. 3 and 4.

[0028] Figure 6 is a diagram schematically showing an example of the result of actually applying the anti-slip control algorithm according to the present invention.

[0029] Fig. 7 is a diagram schematically showing another example of the result of actually applying the anti-slip control algorithm according to the present invention.

[0030] Figure 8 is a diagram schematically showing another example of the result of actually applying the anti-slip control algorithm according to the present invention.

[0031] Figure 9 is a block diagram showing an example of a low-temperature escape prevention device according to the present invention.

[0032] According to one embodiment of the present invention for solving the above technical problem, a method comprises: starting a stopped motor in a first mode, thereby increasing the speed of the motor to a first RPM value at which a first counter electromotive force starts to be measured; monitoring whether the speed of the motor is stably maintained at the first RPM value; if the monitoring result shows that the speed of the motor is maintained at the first RPM value, processing the first counter electromotive force to produce a first counter electromotive force processed value and a second counter electromotive force processed value; estimating the magnitude of a harmonic component of the first counter electromotive force using a result of comparing the produced first counter electromotive force processed value and the second counter electromotive force processed value; determining whether the motor is in a normal rotation state by analyzing the magnitude of the estimated harmonic component; if the motor is in a normal rotation state, increasing the speed of the motor to a second RPM value; And in the process of increasing to the second RPM value, if the motor maintains a normal rotation state, a step of controlling the motor to further increase the speed of the motor to a third RPM value and switch the motor to the second mode is included.

[0033] In the above method, the first mode may be an open-loop operation mode, and the second mode may be a sensor-less operation mode.

[0034] In the above method, the step of calculating the first counter electromotive force processing value and the second counter electromotive force processing value may calculate the first counter electromotive force processing value and the second counter electromotive force processing value, respectively, using an LPF (Low Pass Filter) based on a filter frequency lower than a preset value.

[0035] In the above method, the first counter electromotive force processing value may be a value calculated by applying an LPF according to the filter frequency to the measured first counter electromotive force, and the second counter electromotive force processing value may be a value calculated based on a result of comparing the measured first counter electromotive force and the first counter electromotive force processing value.

[0036] In the above method, the motor may be an IPM (Interior Permanent Magnet) motor.

[0037] In the above method, the motor may be a motor driven by a sensor-less control method.

[0038] According to another embodiment of the present invention for solving the above technical problem, a device is provided as a device for preventing a rotor of a motor from being out of sync at low temperatures, comprising: a memory storing at least one program; And a processor that performs an operation by executing at least one program; wherein the processor starts the stopped motor in a first mode, thereby increasing the speed of the motor to a first RPM value at which a first counter electromotive force starts to be measured, monitors whether the speed of the motor is stably maintained at the first RPM value, and if the speed of the motor is maintained at the first RPM value as a result of the monitoring, processes the first counter electromotive force to calculate a first counter electromotive force processed value and a second counter electromotive force processed value, estimates the magnitude of a harmonic component of the first counter electromotive force using a result of comparing the calculated first counter electromotive force processed value and the second counter electromotive force processed value, and determines whether the motor is in a normal rotation state by analyzing the magnitude of the estimated harmonic component, and if the motor is in a normal rotation state, increases the speed of the motor to a second RPM value, and if the motor maintains a normal rotation state in the process of increasing to the second RPM value, further increases the speed of the motor to a third RPM value to operate the motor in the second mode. You can control it to switch.

[0039] One embodiment of the present invention can provide a computer-readable recording medium storing a program for executing the above method.

[0040] The present invention is capable of various modifications and embodiments. Specific embodiments are illustrated in the drawings and described in detail in the detailed description. The effects and features of the present invention, as well as the methods for achieving them, will become clearer with reference to the embodiments described in detail below, along with the drawings. However, the present invention is not limited to the embodiments disclosed below and can be implemented in various forms.

[0041] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. When describing with reference to the drawings, identical or corresponding components are given the same drawing reference numerals, and redundant descriptions thereof will be omitted.

[0042] In the following examples, the terms first, second, etc. are not used in a limiting sense, but are used for the purpose of distinguishing one component from another.

[0043] In the examples below, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0044] In the following examples, terms such as “include” or “have” mean that a feature or component described in the specification is present, and do not preclude the possibility that one or more other features or components may be added.

[0045] In some embodiments, where the implementation is otherwise feasible, a particular process sequence may be performed in a different order than described. For example, two processes described in succession may be performed substantially simultaneously, or in a reverse order from the described order.

[0046] Hereinafter, a device implementing a method for preventing a motor rotor from losing its synchronism at low temperatures according to the present invention will be abbreviated as a "low-temperature loss-prevention device." The low-temperature loss-prevention device according to the present invention is physically or logically incorporated into various vehicles and functions as a device that controls the operating characteristics of a motor for driving an oil pump, a fuel pump, a water pump, etc.

[0047] The low-temperature step-out prevention device according to the present invention is considered to be capable of a stable sensor-less starting mode with a counter electromotive force by a rotational force of at least X1 RPM. Here, X1 is pre-stored in the memory of the low-temperature step-out prevention device, and depending on the embodiment, the pre-stored value may be changed. As an example, X1 may be 300, but may vary depending on the embodiment. The value of the counter electromotive force of the motor can be measured even when the motor is in an extremely slow state, but if this value is compared with the actual rotational state of the motor, a step-out phenomenon of the motor can be detected. Here, the step-out phenomenon means a phenomenon in which a current of a constant frequency is applied to the motor, but the motor does not operate normally and vibrates (shakes) due to a high load. Typically, a low-temperature loss-of-synchronization prevention device cannot directly detect a loss-of-synchronization phenomenon of a motor through the results of observing the motor's counter electromotive force. Instead, when the motor's rotor is not rotating and is vibrating, it can definitively detect a loss-of-synchronization phenomenon of the rotor by additionally observing the harmonic phenomenon of the counter electromotive force proportional to the rotational force.

[0048] In order for the low-temperature loss-of-step prevention device to observe the harmonic phenomenon of the counter electromotive force, a total of two stages of filtering processes are required. When the low-temperature loss-of-step prevention device detects the harmonic phenomenon, it determines that the rotor is not rotating and can reduce the speed of the motor rotor to X2RPM. At this time, the reason why the low-temperature loss-of-step prevention device reduces the speed of the motor rotor is because the pump operated by the motor requires a torque equivalent to the square of the rotational speed of the impeller. At this time, the impeller is a type of rotor used to increase the pressure and flow of the fluid, and can be interpreted equivalently to the rotor in the present invention.

[0049] That is, if a step-out is detected during open-loop acceleration from the motor's standstill to the 300 RPM state required for measuring the counter electromotive force, the low-temperature step-out prevention device reduces the speed of the motor (the RPM value of the motor's impeller) to reduce the load caused by the flow rate generated by the impeller, thereby controlling the motor to be able to handle the reduced load through the maximum torque that the motor can generate.

[0050] When the motor speed is reduced and the rotor rotates at a low speed again, the cryogenic synchronizing device accelerates the rotor speed again. The above active open-loop speed control algorithm can gradually eliminate the oil friction phenomenon in the pipeline caused by the cryogenic standstill state. As the oil circulates throughout the vehicle's system, the oil temperature rises, and at the same time, the load on the motor decreases, and due to the actively generated open-loop speed, the motor reaches X1 RPM, which can be stably switched to the sensor-less starting mode, and can be stably operated after switching to the sensor-less starting mode. In this specification, the speed profile collected while operating the cryogenic synchronizing device in an actual cryogenic pump will be described through FIGS. 6 to 8, and how the open-loop synchronizing device operates in an actual system while changing the motor load in a dynamo system will be described.

[0051] FIG. 3 is a flowchart showing an example of scripts of a loss prevention control algorithm installed in a low-temperature loss prevention device according to the present invention.

[0052] The method according to FIG. 3 can be implemented by the low-temperature escape prevention device according to the present invention, and any description that overlaps with what has already been described will be omitted. Furthermore, the flowchart illustrated in FIG. 3 comprehensively describes the script of the low-temperature escape prevention device, and depending on the embodiment, it may not necessarily be selective or may not proceed in a time-series manner.

[0053] The low-temperature escape prevention device can initiate an escape prevention control algorithm by executing a program stored in memory (S305).

[0054] The low-temperature loss prevention device can operate a stopped motor in an open-loop start mode to gradually increase the speed of the motor (the speed of the motor's rotor) and check whether it reaches A rpm (S310). In step S310, the low-temperature loss prevention device can check the speed of the motor at regular intervals.

[0055] If the speed of the motor operating in open-loop start mode quickly reaches A rpm (S315), the low-temperature loss-of-speed prevention device may consider that a loss-of-speed phenomenon has occurred, stop the motor, and terminate the loss-of-speed prevention control algorithm (S320). In particular, the low-temperature loss-of-speed prevention device does not check the speed of the motor in real time, but rather monitors it periodically, so the speed of the motor may quickly reach A rpm or reach a value higher than A rpm.

[0056] Meanwhile, the low-temperature anti-slip device gradually increases the speed of the motor in open-loop operation mode, and the counter electromotive force E gamma It can be determined whether the value that can be observed has been reached (S325). At this time, the counter electromotive force may be the minimum counter electromotive force value corresponding to the preset size. In addition, at this time, E gamma The speed of the motor at which the counter electromotive force can be observed may be slower than A rpm. The low-temperature anti-synchronization device can additionally monitor the motor for a preset period of time (several seconds) to ensure that the motor is operating stably while the counter electromotive force is observed at step S325, thereby confirming that the motor has not yet experienced a counter-synchronization phenomenon.

[0057] Low temperature anti-freeze device is E gamma After the motor is observed to operate stably for several seconds, the back electromotive force E gamma By applying a low pass filter (LPF) based on a preset low frequency value, E gamma _Produce LPF, E gamma As a derivative of _LPF, Egamma _High_Err can be calculated (S330). The counter electromotive force E observed in step S325 gamma Since the silver is obtained as a waveform (function) over time, the low-temperature anti-slip device can selectively obtain only the low-frequency component by applying an LPF to the counter electromotive force. In step S330, E gamma _LPF is the low frequency component of the counter electromotive force, and E gamma _High_Err is a derivative of the low-frequency component value of the counter electromotive force, and is defined as the value obtained by subtracting the low-frequency component value of the counter electromotive force from the counter electromotive force.

[0058] Next, the low temperature escape prevention device is E produced in step S330. gamma By applying a low-pass filter again to _High_Err, E gamma Produces _High_Err_LPF, and E gamma E in _LPF gamma By subtracting _High_Err_LPF, Diff_E gamma _THD_RMS can be calculated (S335). During steps S330 and S335, the low-temperature loss prevention device can continuously determine whether the motor speed is maintained stably, as described in step S325 (S340). If the motor speed is still maintained stably in step S340, the low-temperature loss prevention device can gradually increase the motor speed in open-loop starting mode to target B rpm according to the process described below (step S405).

[0059] If the low temperature escape prevention device detects that the speed of the motor is not maintained stably in step S340, the Diff_E calculated in step S335 gamma Determine whether _THD_RMS is greater than the preset X (S345), and Diff_E gammaIf _THD_RMS is greater than X, the low-temperature loss-of-speed prevention device, as described in step S325, continuously determines whether the speed of the motor is maintained stably by setting the Stable_A_RPM_Cnt value to the time during which the speed of the motor is stably operated (S350), and compares whether the value is greater than the preset Stable_Period (S355), and if so, the speed of the motor can be gradually increased while normally maintaining the open-loop starting mode (S360). If the Stable_A_RPM_Cnt value is less than the Stable_Period in step S350, the loss-of-speed prevention control algorithm can be terminated (S365).

[0060] Meanwhile, the low temperature anti-slip device is Diff_E calculated in step S335 gamma Determine whether _THD_RMS is greater than the preset X (S345), and Diff_E gamma If _THD_RMS is not greater than X, the process can be started to count the number of failures in the open-loop start mode and restart the synchronizing prevention control algorithm (S370, S375, S380). At this stage, the motor is in a state where it cannot operate at a stable speed while operating in the open-loop start mode while generating the minimum counter electromotive force, and the motor is stopped for a while. Later, when the user inputs or the synchronizing prevention control algorithm is run again after the preset waiting time has elapsed, the motor will operate again.

[0061] Figure 4 is a flowchart for explaining an example of the scripts of the anti-slip control algorithm described in Figure 3.

[0062] In Fig. 4, the low-temperature anti-slip device still stably generates the counter electromotive force E when the motor speed is increased from A rpm to B BRM in open-loop operation mode. gammaWhile generating the Diff_E, it is determined whether the de-synchronization phenomenon is not detected (S405), and if the de-synchronization phenomenon is still not detected, then Diff_E gamma It can be determined whether _THD_RMS is greater than X (S410). In step S410, Diff_E gamma If it is determined that _THD_RMS is greater than X, the low-temperature loss-of-step prevention device may further gradually increase the speed of the motor in the open-loop start mode to increase it to 400 RPM, which is the preset sensor-less start mode transition threshold. The low-temperature loss-of-step prevention device may determine whether the speed of the motor in the open-loop start mode has reached 400 RPM (S415), and if so, may switch the motor operation mode from the open-loop start mode to the sensor-less mode (S420). If the low-temperature loss-of-step prevention device does not properly determine whether the speed of the motor in the open-loop start mode has reached 400 RPM, the motor may continue to increase its speed to be greater than 400 RPM while maintaining the open-loop start mode, and after a certain period of time, an interrupt function may be triggered to stop the motor (S425).

[0063] Meanwhile, in step S410, the low temperature escape prevention device, Diff_E gamma If it is determined that _THD_RMS is not greater than X, the number of open loop failures is added once more (S430), the currently accumulated number of open loop failures is compared with a preset value (S435), and the speed of the motor is lowered from B rpm to A rpm (S440), or the anti-synchronization control algorithm is terminated (S445).

[0064] The low temperature anti-synchronization device is still stable in the open loop starting mode at step S405, when the motor speed is increased from A rpm to B BRM. gamma Determine whether the counter electromotive force E is generated gamma If it is determined that this does not occur stably, the Diff_E produced in step S335 gammaIt can be determined whether _THD_RMS is greater than X (S450). The low-temperature loss prevention device is Diff_E gamma If _THD_RMS is greater than X, Stable_B_RPM_Cnt can be added one more time (S455). In step S455, Stable_B_RPM_Cnt is a value for the number of times (count) that the motor speed is observed to operate stably at B rpm, and is initially set to 0 as a default value, and can be incrementally added as the motor starts operating.

[0065] The low-temperature loss-of-step prevention device determines whether the currently updated Stable_B_RPM_Cnt is greater than the preset Stable_Period (S460), and if so, assigns Stable_B_RPM_F to True, increases the current motor speed in the open-loop start mode from B rpm to C rpm, and initializes the number of failures in the open-loop start mode, Openloop_Fail_Cnt, to 0 (S465). The low-temperature loss-of-step prevention device terminates the loss-of-step prevention control algorithm if the currently updated Stable_B_RPM_Cnt is not greater than the preset Stable_Period (S470).

[0066] At step S450, the low temperature anti-slip device is Diff_E gamma If _THD_RMS is not greater than X, Stable_A_RPM_Cnt can be initialized to 0 and Openloop_Fail_Cnt can be increased by 1 more time (S475). Next, the low-temperature loss-of-step prevention device compares Openloop_Fail_Cnt with a preset Period value, and if Openloop_Fail_Cnt is greater, the speed of the motor can be lowered from B rpm to A rpm again (S485) or the loss-of-step prevention control algorithm can be terminated (S490).

[0067] FIG. 5 is a flowchart illustrating another example of the anti-slip control algorithm described in FIGS. 3 and 4.

[0068] More specifically, FIG. 5 can be understood as a method that re-describes the method performed by the low-temperature anti-slip device described in FIGS. 3 and 4 in a way that highlights its technical features. Since the method according to FIG. 5 can be implemented by the low-temperature anti-slip device described in FIGS. 3 and 4, any description that overlaps with what has already been described will be omitted.

[0069] The low-temperature escape prevention device can increase the speed of the motor to a first RPM value at which the first counter electromotive force begins to be measured by starting the stopped motor in the first mode (S510). The speed of the motor measured in step S510 is in RPM units, and the first RPM value may correspond to A rpm described in FIG. 3. In step S510, the motor may be an IPM (Interior Permanent Magnet) motor. In addition, in step S510, the motor may be a motor driven by a sensor-less control method.

[0070] The low-temperature anti-slip device can monitor whether the speed of the motor is stably maintained at the first RPM value (S520).

[0071] As a result of monitoring the speed of the motor in step S520, if the speed of the motor is stably maintained at the first RPM value, the low-temperature anti-slip device can process the first counter electromotive force generated at the first RPM to calculate the first counter electromotive force processing value and the second counter electromotive force processing value (S530).

[0072] The low-temperature anti-slip device can estimate the size of the harmonic component of the first counter electromotive force by using the result of comparing the first counter electromotive force processing value and the second counter electromotive force processing value calculated in step S530 (S540).

[0073] The low-temperature loss prevention device can determine whether the motor is in a normal rotation state by analyzing the size of the harmonic component estimated in step S540 (S550).

[0074] The low-temperature anti-slip device can increase the speed of the motor from the first RPM value to the second RPM value when the motor is in normal rotation state (S560).

[0075] The low-temperature anti-slip device can control the motor to change its operating mode from the first mode to the second mode by further increasing the speed of the motor to the third RPM value if the motor still maintains a normal rotation state during the process of increasing the speed of the motor to the second RPM value (S570).

[0076] In Fig. 5, the first mode may be an open-loop start mode, and the second mode may be a sensor-less start mode. In addition, the first RPM value, the second RPM value, and the third RPM value are exemplary values ​​for explaining that the speed of the motor gradually increases step by step and ultimately switches from the open-loop start mode to the sensor-less start mode, and the first RPM value may be set to the smallest value, and the third RPM value may be set to the largest value. As an example, the third RPM value may be 400, as in step S415, but is not limited thereto.

[0077] In the present invention, the section in which the motor is accelerated from a stopped state to a first RPM value (e.g., A rpm) may be abbreviated as the first stage, the section in which the speed of the motor is accelerated from the first RPM value to a second RPM value (e.g., B rpm) may be abbreviated as the second stage, and the section in which the speed of the motor is accelerated from the second RPM value to a third RPM value (e.g., C rpm, 300 RPM, or 400 RPM) and then switched to a sensor-less mode may be abbreviated as the third stage. As illustrated in FIGS. 3 and 4, the low-temperature loss-of-speed prevention device can control the speed of the motor to be switched from an open-loop starting mode to a sensor-less starting mode while continuously determining whether the motor is operating stably while exhibiting a constant counter electromotive force and processing the first to third stages in a time series or cyclical manner.

[0078] The low-temperature step-out prevention device according to the present invention can minimize the occurrence of step-out phenomena when the motor operates in a sensor-less starting mode at low temperatures through a detailed control process as described above, and can also prevent the phenomenon of the motor suddenly stopping due to insufficient torque caused by a situation where the viscosity of the pipeline is still high when switching to the sensor-less starting mode in a short period of time due to excessive torque generation. In particular, the low-temperature step-out prevention device according to the present invention is designed so that when harmonics are detected in the acceleration sections of the second and third stages and the rotor shakes, the speed of the motor is decelerated to the first stage so that protection (or interruption) does not occur immediately, thereby reducing the load on the pump and allowing the motor to rotate without suddenly stopping.

[0079] For motor-driven oil and water pumps, stable startup is more important than rapid start-up at cryogenic temperatures. In other words, motor-driven pumps must operate reliably and sensorlessly, without protection, at cryogenic temperatures.

[0080] Unlike the present invention, when the rotor vibrates when the motor is started from a standstill at an extremely low temperature to the 300 RPM required for sensorless mode, unlike the known technology, if the rotor is immediately accelerated in open-loop start mode and then sensorless switching is performed, an unexpectedly large current is generally suddenly generated in the FET. If the above phenomenon is repeated multiple times, the life of many components constituting the automobile may be reduced.

[0081] According to the prior art, it is not possible to know when the friction loss in the pipeline due to the cryogenic oil will decrease, and if an external cryogenic phenomenon is detected, the logic is used to rotate the motor for a time tuned through testing at a specific RPM and then accelerate so that it can operate according to the temperature of -35 degrees Celsius. However, this logic has the problem of having to consider the oil dispersion characteristics in advance and having to be readjusted if the motor specifications change. Moreover, according to the prior art, even at low temperatures higher than -35 degrees Celsius, the operation is performed according to the value set based on -35 degrees Celsius, which also causes a problem of loss of operating time.

[0082] The present invention has the characteristic of detecting signs of rotor out-of-synchronization during open-loop acceleration in advance and actively controlling speed deceleration or acceleration repeatedly, thereby quickly resolving the high viscosity state of the pipeline due to cryogenic oil, reducing pipeline friction loss, and stably switching to a sensor-less operation mode without causing motor protection. In addition, the present invention has the excellent characteristic of not requiring unnecessary tuning points (oil distribution characteristics, motor specifications, -35 degrees Celsius standard, etc.) unlike the prior art.

[0083] Figure 6 is a diagram schematically showing an example of the result of actually applying the anti-slip control algorithm according to the present invention.

[0084] In Fig. 6, the two waveforms are the same test waveforms, and the first is a waveform that shows the variable values ​​of the internal logic with a DAC (Digital - Analog Conversion) using an oscilloscope. In Fig. 6, the blue graph shows the speed of the motor (in RPM), and the pink graph shows the low-frequency component of the counter electromotive force, E gamma _LPF, the green graph is E gamma _High_Err_LPF respectively.

[0085] In Figure 6, section ⓐ shows that the motor is rising to A rpm and then rising to B rpm, but the loss of speed is detected and it is returned to A rpm. The low-temperature loss prevention device is E gamma _LPF is E gamma _High_Err_Lpf must be greater than that to detect that the motor rotor (impeller) is rotating normally, but as the load on the impeller increases while the motor speed increases from A rpm to B rpm, E gamma _Lpf decreases and E gamma _High_Err_Lpf was reduced, and as a result, a step-out was detected. According to the step-out in the open-loop starting mode using a dynamo, which will be described later through Fig. 8, it can be further clarified that section ⓐ in Fig. 6 is the section where a step-out was detected.

[0086] As shown in Fig. 6, after a total of two de-synchronizations, the motor speed (motor rotor speed) reaches B rpm. This phenomenon is due to the phenomenon in which the pump draws up oil, gradually filling the pipeline with oil, thereby reducing frictional loss of the oil due to extremely low temperatures.

[0087] Section ⓑ of Fig. 6 is a section in which the low-temperature loss-of-speed prevention device maintains the motor speed at B rpm and reduces pipe friction. The low-temperature loss-of-speed prevention device can reach the desired motor speed by directly accelerating the motor speed and continuously causing the speed to return to A rpm. However, the number of repetitions in which the motor speed returns to A rpm can be minimized by sufficiently releasing the load on the pipe without rapidly accelerating the motor speed. Referring to section ⓑ of Fig. 6, it can be confirmed that Egamma_Lpf gradually increases when B rpm is maintained, and the load due to viscous friction on the pipe is reduced.

[0088] Section ⓒ of Fig. 6 is the section where the motor speed increases to a speed that can be switched to the sensor-less start mode after satisfying B rpm by the low-temperature loss-of-synchronization prevention device. In section ⓒ of Fig. 6, one more loss-of-synchronization was detected. Since the motor speed was stably maintained at B rpm in the previous status, the motor speed temporarily returns to A rpm by the low-temperature loss-of-synchronization prevention device and is designed to immediately accelerate to the speed (300 RPM) for switching to the sensor-less start mode.

[0089] Section ⓓ of Fig. 6 schematically shows that the motor is stably controlled by the BEMF_Observer because the transition to the sensor-less start mode is performed stably. Comparing section ⓓ of Fig. 6 with section ⓒ, assuming that the low-temperature loss-of-synchronization prevention device did not detect a single loss-of-synchronization phenomenon in section ⓒ and the motor speed did not return to A rpm, the load would be so high that the open-loop start mode would not have been stably operated. Even if the open-loop start mode was transitioned to the sensor-less start mode without a problem, the load at the time of transition would be so large that the motor would eventually lose synchronism as soon as section ⓓ is entered, and protection would be performed.

[0090] As described in FIG. 6, the present invention is very convenient because the user does not have to worry about how long and at what speed to operate the open loop operation mode in order to solve the friction loss of the pipeline caused by oil or the like at extremely low temperatures.

[0091] Fig. 7 is a diagram schematically showing another example of the result of actually applying the anti-slip control algorithm according to the present invention.

[0092] FIG. 7 schematically illustrates the speed information, flow rate information, and pressure information of the motor measured at the equipment stand in a case where the anti-synchronization control algorithm according to the present invention is applied as described in FIG. 6. In particular, the flow rate information and pressure information in each section in FIG. 7 are very important information that allow the user to immediately know the status of the pump, not the motor.

[0093] In section ⓐ of Fig. 7, the user can see that although the motor speed has increased to A rpm, the flow rate is 0, indicating that the entire pipeline is not yet filled with oil, and that the pressure is gradually increasing due to air. Furthermore, the user can interpret the information in section ⓐ to anticipate that the load will rapidly increase.

[0094] Next, in section ⓑ of Fig. 7, the user can see that the motor is continuously rotating, as the speed of the motor repeats sections A and B rpm a total of two times. In addition, the user can confirm that oil is gradually filling up the pipe, and that the flow rate is observed in the flow meter of the output terminal from section ⓑ.

[0095] Next, in the ⓒ section of Fig. 7, the user can confirm that a constant flow rate is being discharged based on the fact that the motor speed is continuously maintained at B rpm, and that the pressure at the output end is maintained constant. In addition, the user can see that B rpm stably drives the motor at the maximum torque that it can produce in the ⓒ section of Fig. 7. In particular, the phenomenon observed in the oscilloscope, that the load is being released in the ⓒ section of Fig. 7, is due to the gradual decrease in the friction loss of the pipe as the oil temperature gradually increases.

[0096] Next, in section ⓓ of Fig. 7, the user can confirm that the speed of the motor is stably maintained at B rpm for a set period of time, and in section ⓓ of Fig. 7, the speed of the motor is accelerated from B rpm to 300 rpm. In section ⓓ of Fig. 7, as the rotational speed of the impeller increases, the flow rate increases and the pressure also increases. In other words, section ⓓ of Fig. 7 is a section in which the load of the motor rapidly increases. In particular, referring to section ⓓ of Fig. 7, it can be seen that during acceleration of the motor, the maximum torque of the motor is exceeded, a step-out occurs, and the speed of the motor rapidly drops to A rpm and then re-accelerates by the regression logic described in Fig. 4.

[0097] Finally, section ⓔ of Fig. 7 is a section where the motor is steadily accelerating in sensorless start mode. After the motor switches to sensorless start mode, the low-temperature escape prevention device can detect the position of the motor's rotor, so the motor can accelerate to the speed commanded by the user, and 500 rpm was input in section ⓔ of Fig. 7.

[0098] Figure 8 is a diagram schematically showing another example of the result of actually applying the anti-slip control algorithm according to the present invention.

[0099] Fig. 8 illustrates, by way of example, the results of an experiment conducted to visually confirm whether the algorithm according to the present invention can accurately detect the motor's out-of-step phenomenon in open-loop operation mode. Specifically, Fig. 8 illustrates information obtained through an oscilloscope during the process of verifying the accuracy of the algorithm according to the present invention prior to applying it to a system, since it is impossible to visually confirm whether the impeller is rotating normally or vibrating when the motor is attached to an actual oil pump.

[0100] Section ⓐ in Fig. 8 is the section where it was confirmed whether stable detection was achieved by applying a load of 1.7 N·m, which is less than the maximum torque of 1.8 N·m of the motor. Referring to section ⓐ in Fig. 8, E gamma _Lpf is E gamma Since it is calculated to be greater than _High_Err_Lpf, it can be seen that the motor is operating normally according to the principle explained above, and it can be confirmed with the naked eye that the motor is rotating stably in the dynamo system.

[0101] Section ⓑ in Fig. 8 is a section where the motor is recognized as being in a stable state and the load is increased to 2.1 N m during acceleration to prevent the motor from rotating. Referring to section ⓑ in Fig. 8, like the previously mentioned anti-synchronization control algorithm, E gamma _Lpf is E gamma It can be confirmed through the waveform that the motor is out of step when it is further away than _High_Err_Lpf, and the phenomenon of the motor shaking was also observed with the naked eye in an actual dynamo. In the ⓑ section of Fig. 8, the reason why the speed value observed by the controller matches the reference speed, Speed ​​Ref, is because the exact position of the rotor cannot be known in the open-loop starting mode. Therefore, since the speed is expressed assuming that the motor is rotating at Speed ​​Ref in the open-loop starting mode logically, the controller's speed information shows that it is rotating at Speed ​​Ref. This phenomenon is the biggest drawback of the open-loop starting, and for the same reason as above, it is necessary to enter a section of 300 rpm or more where the BEMF Observer can stably determine the position of the N pole of the motor.

[0102] In the ⓒ section of Fig. 8, the results of checking whether the loss of synchronism and normal rotation were determined in the Stable section by repeatedly changing the load between 1.7 N·m and 2.1 N·m at a point where the motor speed is A rpm are schematically shown. In fact, in the ⓒ section of Fig. 8, the loss of synchronism and normal rotation were determined very accurately, and the results observed with the naked eye were also the same.

[0103] Section ⓓ of Fig. 8 can be understood as a section to check whether the motor is operated stably until the point of transition to the sensor-less operation mode by applying 1.7 N·m to the motor and rotating it normally, since the motor's loss of synchronism and normal rotation were well determined in section ⓒ.

[0104] Figure 9 is a block diagram showing an example of a low-temperature escape prevention device according to the present invention.

[0105] Hereinafter, the low-temperature escape prevention device (900) of FIG. 9 is the same device as the low-temperature escape prevention device described in FIGS. 2 to 7, and therefore, it is considered that all processes of the low-temperature escape prevention device described in FIGS. 2 to 7 can be implemented. As described above, the low-temperature escape prevention device (900) can function as a device to assist the operation of a motor used in the process of operating a pump included in a vehicle such as an automobile or a bus, and therefore, can be included as a module (physically) or application (logically) in the interior of a tractor or other work vehicle.

[0106] Referring to FIG. 9, the low-temperature anti-slip device (900) may include a communication unit (910), a processor (920), and a database (930). Only components related to the embodiment are illustrated in the low-temperature anti-slip device (900) of FIG. 9. Therefore, those skilled in the art will understand that other general-purpose components may be included in addition to the components illustrated in FIG. 9.

[0107] The communication unit (910) may include one or more components that enable wired / wireless communication with an external server or external device. For example, the communication unit (910) may include at least one of a short-range communication unit (not shown), a mobile communication unit (not shown), and a broadcast receiving unit (not shown).

[0108] DB (930) is hardware that stores various data processed within the low-temperature dehydration prevention device (900), and can store a program for processing and controlling the processor (920).

[0109] DB (930) may include random access memory (RAM) such as dynamic random access memory (DRAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), CD-ROM, Blu-ray or other optical disk storage, hard disk drive (HDD), solid state drive (SSD), or flash memory.

[0110] The processor (920) controls the overall operation of the low-temperature anti-slip device (900). For example, the processor (920) can control the input unit (not shown), the display (not shown), the communication unit (910), the DB (930), etc., by executing programs stored in the DB (930). The processor (920) can control the operation of the low-temperature anti-slip device (900) by executing programs stored in the DB (930).

[0111] As an example, the processor (920) increases the speed of the motor to a first RPM value at which a first counter electromotive force starts to be measured by starting a stopped motor in a first mode, monitors whether the speed of the motor is stably maintained at the first RPM value, and if the speed of the motor is maintained at the first RPM value as a result of the monitoring, processes the first counter electromotive force to calculate a first counter electromotive force processed value and a second counter electromotive force processed value, estimates the magnitude of the harmonic component of the first counter electromotive force using the result of comparing the calculated first counter electromotive force processed value and the second counter electromotive force processed value, and determines whether the motor is in a normal rotation state by analyzing the magnitude of the estimated harmonic component, and if the motor is in a normal rotation state, increases the speed of the motor to a second RPM value, and if the motor maintains a normal rotation state during the process of increasing to the second RPM value, controls the motor to be switched to the second mode by further increasing the speed of the motor to a third RPM value.

[0112] The processor (920) may be implemented using at least one of application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), controllers, micro-controllers, microprocessors, and other electrical units for performing functions.

[0113] The embodiments of the present invention described above may be implemented in the form of a computer program that can be executed through various components on a computer, and such a computer program may be recorded on a computer-readable medium. At this time, the medium may include a magnetic medium such as a hard disk, a floppy disk, and a magnetic tape, an optical recording medium such as a CD-ROM and a DVD, a magneto-optical medium such as a floptical disk, and a hardware device specifically configured to store and execute program instructions, such as a ROM, a RAM, a flash memory, etc.

[0114] Meanwhile, the computer program may be specifically designed and constructed for the present invention, or may be one known and available to those skilled in the computer software field. Examples of computer programs may include not only machine language code, such as that generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like.

[0115] The specific implementations described in the present invention are exemplary embodiments and do not limit the scope of the present invention in any way. For the sake of brevity, descriptions of conventional electronic components, control systems, software, and other functional aspects of the systems may be omitted. In addition, the lines connecting or connecting members between components illustrated in the drawings are merely representative of functional connections and / or physical or circuit connections, and may be replaced or represented as various additional functional connections, physical connections, or circuit connections in an actual device. In addition, unless specifically mentioned as “essential,” “important,” etc., a component may not be absolutely necessary for the application of the present invention.

[0116] The use of the term "above" and similar referential terms in the specification of the present invention (especially in the claims) may refer to both singular and plural. Furthermore, if a range is described in the present invention, it includes inventions that apply individual values ​​within the range (unless otherwise stated), and is equivalent to describing each individual value constituting the range in the detailed description of the invention. Finally, unless the order of the steps constituting the method according to the present invention is explicitly stated or otherwise stated to the contrary, the steps may be performed in any appropriate order. The present invention is not necessarily limited by the order in which the steps are described. The use of all examples or exemplary terms (e.g., "for example," etc.) in the present invention is merely intended to illustrate the present invention in detail, and the scope of the present invention is not limited by the examples or exemplary terms, unless otherwise defined by the claims. Furthermore, those skilled in the art will appreciate that various modifications, combinations, and variations can be made within the scope of the appended claims or their equivalents, depending on design conditions and factors.

[0117] One embodiment of the present invention can be used in an industry that manufactures sensor-less motors.

Claims

1. A step of starting a stopped motor in the first mode to increase the speed of the motor to a first RPM value at which the first counter electromotive force starts to be measured; A step of monitoring whether the speed of the above motor is stably maintained at the first RPM value; As a result of the above monitoring, if the speed of the motor is maintained at the first RPM value, a step of processing the first counter electromotive force to calculate a first counter electromotive force processing value and a second counter electromotive force processing value; A step of estimating the size of the harmonic component of the first counter electromotive force by using the result of comparing the first counter electromotive force processing value and the second counter electromotive force processing value produced above; A step of analyzing the size of the estimated harmonic component to determine whether the motor is in a normal rotation state; When the above motor is in a normal rotation state, a step of increasing the speed of the motor to a second RPM value; and A method for preventing a motor rotor from losing its synchronism at low temperatures, comprising: a step of controlling the motor to further increase its speed to a third RPM value and switch the motor to a second mode when the motor maintains a normal rotation state during the process of increasing the speed to the second RPM value.

2. In paragraph 1, The above first mode is an open loop operation mode, The second mode is a method for preventing the rotor of a motor from losing its synchronism at low temperatures, which is a sensor-less operation mode.

3. In paragraph 1, The step of calculating the first and second counter electromotive force processing values ​​is as follows: A method for preventing the rotor from losing its synchronism at low temperatures, wherein a first counter electromotive force processing value and a second counter electromotive force processing value are each calculated using a LPF based on a filter frequency lower than a preset value.

4. In paragraph 3, The above first reverse electromotive force processing value is, This is a value calculated by applying LPF according to the filter frequency to the first counter electromotive force measured above, The above second reverse electromotive force processing value is, A method for preventing the rotor slippage of a motor at low temperatures, the method comprising: calculating a value based on a comparison of the measured first counter electromotive force and the first counter electromotive force processing value.

5. In paragraph 1, The above motor, A method for preventing rotor slippage of an IPM (Interior Permanent Magnet) motor at low temperatures.

6. In paragraph 1, The above motor, A method for preventing rotor slippage of a motor at low temperatures, the motor being driven by a sensor-less control method.

7. A computer-readable recording medium storing a program for executing the method according to Article 1.

8. As a device to prevent the rotor from slipping at low temperatures, memory in which at least one program is stored; and A processor that performs an operation by executing at least one program; The above processor, By starting the stopped motor in the first mode, the speed of the motor is increased to the first RPM value at which the first counter electromotive force starts to be measured, Monitor whether the speed of the above motor is stably maintained at the first RPM value, As a result of the above monitoring, if the speed of the motor is maintained at the first RPM value, the first counter electromotive force is processed to calculate the first counter electromotive force processing value and the second counter electromotive force processing value. The size of the harmonic component of the first counter electromotive force is estimated using the results of comparing the first counter electromotive force processing value and the second counter electromotive force processing value. By analyzing the size of the above estimated harmonic components, it is determined whether the motor is in normal rotation state, When the above motor is in normal rotation state, increase the speed of the motor to the second RPM value, A device for preventing the rotor from slipping out of sync at low temperatures, which controls the speed of the motor to be further increased to a third RPM value so that the motor is switched to a second mode when the motor maintains a normal rotation state during the process of increasing to the second RPM value.

Images