1230 results about "Low speed" patented technology

Disclosed is a low-precision incremental encoder-based method for ultra-low speed control of a servo system. According to the present invention, a fast speed observer in an ultra-low-speed working state is achieved, only a sampling speed and load torque in an M / T method need to be observed, and position information of an electric motor does not need to be observed, such that the structure of the observer is simplified, and calculation is simple and fast; moreover, the influence of a friction force and cogging torque on a speed change is considered, such that the speed observation precision is further improved. The fast speed observer can reduce hysteresis and measurement dead zones, such that the speed response and the speed control precision in a low-speed working state are greatly improved, the problem in a traditional observer of a large position deviation caused by nonlinear factors such as an external load is avoided, improving the stability and robustness of the system. According to the present invention, the processing of sampling measurement time at a medium-high speed and the processing of switching the observer at a low speed in the M / T method can optimize the speed measurement precision at both the medium-high speed and the ultra-low speed, and can better satisfy the requirements of apparatuses such as a radar on rotating speed control.

Disclosed in the present application is a wheel anti-lock braking system applicable to hill braking. In the wheel anti-lock braking system, a wheel speed identification module is used for identifying a vehicle wheel speed signal and a wheel acceleration signal; a vehicle speed acquisition module is used for calculating a vehicle body speed signal; a driving intention identification module is used for obtaining a front and a rear axle enable flag bit; a state machine module is used for determining whether the working state of a low-speed hill anti-lock braking system is a standby state or a shutdown state, and starting a conventional anti-lock braking system when the working state of the low-speed hill anti-lock braking system is a shutdown state; the state machine module receives the front and rear axle enable flag bits, and transmits the front and rear axle enable flag bits to a control logic module when the working state of the low-speed hill anti-lock braking system is a standby state; and the control logic module is used for sending a low-speed hill anti-lock braking system control command when wheels show a tendency to lock up. The present application realizes anti-lock braking control over wheels at low speeds, especially during hill braking, which cannot be achieved by conventional wheel anti-lock braking systems.

The invention provides a switched reluctance motor low-speed rotor position estimation method, and belongs to the technical field of switched reluctance motor control. The method comprises the following steps: firstly, discretizing a winding voltage equation of the switched reluctance motor, obtaining predicted current of each phase through programming calculation and formula recombination of a controller, and acting the predicted current on hysteresis control of a conduction region; secondly, in combination with a partition PWM hysteresis variable-duty-ratio pulse injection method, setting three high-frequency pulses with different duty ratios to be injected into a conduction region, a follow current region and a non-conduction region respectively, and increasing the number of sampling current slope difference values when a switch tube in the conduction region is switched off; and finally, performing logic combination and comparison on the three-phase current slope difference curve generated by calculation to obtain a real-time rotor position. According to the method, the rotor position estimation precision is improved, the rotating speed range is widened, the amplitude of response current in a non-conducting region is limited, negative torque is avoided, and low-speed stable operation of the motor is facilitated.

The invention relates to an ice and snow disaster variable speed limit control method and system based on a friction coefficient, and belongs to the field of intelligent traffic. According to the method, a set of variable speed limit control units are arranged on a road at intervals, and all the variable speed limit control units are in communication connection with a centralized decision-making unit through communication modules; each set of variable speed-limiting control unit detects traffic flow data, meteorological environment data and road condition data of a lane level in real time, uploads the data to the centralized decision-making unit, determines an optimal lane-level variable speed-limiting control scheme and an optimal deicing and snow-removing scheme through a decision-making optimization algorithm, and issues the optimal lane-level variable speed-limiting control scheme and the optimal deicing and snow-removing scheme to the variable speed release module; and the variable speed release module releases a lane level variable speed limit control scheme of a corresponding section, namely the lowest speed limit value, the highest speed limit value, the suggested speed and the like of each lane, and performs deicing and snow removal operation according to the deicing and snow removal scheme so as to ensure road traffic safety in ice and snow weather. The road traffic safety guarantee level is improved through variable speed limiting.

The invention discloses a permanent magnet synchronous motor extremely-low-speed robust position sensorless control method, device and system. The method comprises the following steps: performing ESO current-disturbance observation on dq-axis current values, voltage reference values and rotor position information at a k moment to obtain an observation current and a q-axis disturbance observation value at a k + 1 moment; the dq-axis current value, the observation current and the dq-axis current reference value at the k moment are observed through a rotor position observer, and the position and the rotating speed of a motor rotor at the k + 1 moment are obtained; adopting a feed-forward compensation method to obtain a q-axis voltage feed-forward value at the k + 1 moment according to the q-axis disturbance observation value at the k + 1 moment and the rotating speed of the motor at the k + 1 moment; and dynamically adjusting a q-axis voltage feed-forward value according to the position of the motor rotor at the k + 1 moment and the q-axis disturbance observation value, and realizing effective suppression of the torque ripple in the low-speed region. According to the method, the robustness and the anti-interference capability of a low-speed region are enhanced while the steady-state performance and the dynamic response of the system are improved.

The invention discloses an automobile lane changing auxiliary system which comprises a steering lamp operating rod assembly, an electronic control unit, a left rearview mirror module, a right rearview mirror module, a position sensor, a rearview mirror position memory module and an automobile state detection module, and the steering lamp operating rod assembly is arranged on the left side of a steering wheel and provided with a neutral position, a first gear and a second gear; the electronic control unit receives an operating rod signal and outputs a control instruction; the left rearview mirror module comprises a left rearview mirror horizontal rotation actuator and a left rearview mirror lens; the right rearview mirror module comprises a right rearview mirror horizontal rotation actuator and a right rearview mirror lens. Therefore, 0-20-degree adjustment of the rearview mirror is related to the vehicle speed, a blind area is covered at a low speed in a large angle, interference is avoided at a high speed in a small angle, risks are reduced, multi-gear linkage simplifies operation, the rearview mirror returns after being loosened, automatic centering is achieved after lane changing, distraction is reduced, navigation and a corner sensor recognize the road condition, manual reset is not needed, and adaptability is high.

The invention discloses a permanent magnet synchronous motor full-speed-domain position-sensorless hybrid control method and a permanent magnet synchronous motor full-speed-domain position-sensorless hybrid control system, and the permanent magnet synchronous motor full-speed-domain position-sensorless hybrid control method is constructed by taking a permanent magnet synchronous motor nonlinear dynamic system model as a starting point. A hybrid control method combining high-frequency pulsating square wave signal injection under a linear dynamic system model, a rotor polarity judgment and rotor initial position estimation algorithm and an unscented Kalman filtering extension algorithm in an additive noise form under a nonlinear discrete dynamic system model is adopted; and obtaining the optimal estimation observation value of the system state variable in the static, low-speed, medium-speed and high-speed full-speed domain range under the condition that the permanent magnet synchronous motor is not provided with a mechanical position sensor. The optimal estimation observation value is used for compensating and feeding back a permanent magnet synchronous motor drive control system adjusting strategy, disturbance of load torque is improved, the noise amount and disturbance amount introduced by three-phase current measurement are eliminated, and efficient and accurate control operation of the permanent magnet synchronous motor is achieved.

The invention relates to the technical field of mortar detection, and discloses a mortar consistency detection device, which comprises a bottom plate, the top of the bottom plate is fixedly connected with a placing seat, the top of the placing seat is provided with a conical cylinder, the bottom of the conical cylinder is provided with a hexagonal hole, the top of the placing seat is fixedly connected with a fixing rod, and the fixing rod is fixedly connected with the bottom of the conical cylinder. The top of the fixing rod is fixedly connected with a supporting ring, the supporting ring makes contact with the outer wall of the conical barrel, a flattening mechanism is arranged on the containing base, and the flattening mechanism comprises a low-speed motor, a rotating rod, a hexagonal block, a fixing block, a first rotating shaft, a fixing plate, an adjusting bolt, a limiting groove, a lifting plate, a limiting rod, a sliding block and a flattening plate. Through mutual cooperation of the low-speed motor, the rotating rod, the hexagonal block and the hexagonal hole, the conical cylinder is driven to rotate at a low speed, so that various components of mortar are distributed more uniformly in the cylinder, abnormal stress of a cone caused by non-uniform components of the mortar is avoided, and a detection result is more accurate.

The invention provides a steering-by-wire vehicle variable transmission ratio design method and system based on a fuzzy neural network, and belongs to the field of vehicle steering-by-wire. According to a fixed gain method, the steering angle transmission ratio is too small at a low speed, and the sensitivity is low at a high speed; the existing intelligent algorithm excessively depends on the experience of a designer and the quality of a data sample. The method comprises the following steps: establishing a closed-loop driver-vehicle system, designing a multi-target evaluation method by using a quadratic cost function of a vehicle dynamic state, and obtaining a data relationship between a vehicle ideal variable transmission ratio characteristic and a vehicle longitudinal speed and a steering wheel angle; a nonlinear control model is established through a fuzzy RBF network, and a globally optimal solution is obtained based on nonlinear model learning. The robustness of the control system is improved, the stable and reliable transmission ratio can be provided under various vehicle conditions, and the problem that a steering system is light and flexible is solved, so that the experience feeling of a driver under various vehicle conditions is improved, and meanwhile the operation stability and safety of the vehicle are improved.

The utility model belongs to the technical field of motors, and relates to a magnetic-adjustable back-wound motor structure, which comprises a stator iron core, the stator iron core comprises an annular stator yoke part, a plurality of stator inner teeth are uniformly distributed on the inner wall of the stator yoke part, and the outer surface of the stator yoke part is respectively provided with a stator outer tooth corresponding to each stator inner tooth; groove-shaped adjustable flux winding upper positioning grooves and adjustable flux winding lower positioning grooves are symmetrically formed in the two sides of the stator outer teeth, adjustable flux windings are wound on the adjustable flux winding upper positioning grooves and the adjustable flux winding lower positioning grooves of the stator outer teeth respectively, and the two sides of coils of the adjustable flux windings are located in the adjustable flux winding upper positioning grooves and the adjustable flux winding lower positioning grooves respectively. The turns of the windings on the two sides are equal; according to the utility model, by arranging the adjustable magnetic windings on the outer stator teeth, the magnetic field modulation effect generated after the adjustable magnetic windings are electrified is utilized to increase and demagnetize the internal magnetic field of the motor and adjust the air-gap magnetic field, thereby realizing transmission of large torque at a low speed or flux-weakening speed expansion at a high rotating speed.

The present invention provides a method for controlling the automatic start of a commercial vehicle AMT, including a control state model and the jump conditions of the control state model. Through the collaborative control of the vehicle control system, the transmission control system, the engine control system and the handle control system, when the vehicle is in the D / R gear position, releasing the foot brake and not stepping on the accelerator, the transmission control system controls the clutch to automatically engage, and the vehicle travels stably at a low speed. When the vehicle encounters other harsh working conditions with large driving resistances such as a large slope, in order to avoid the risk of engine stalling, the engagement depth of the clutch is adjusted in real time to ensure the power response and driving smoothness of the vehicle's automatic start condition, and enhance the driver's control performance.

The invention provides a road adhesion coefficient estimation method based on an adaptive slip speed tire model. The method comprises the following steps: establishing a vehicle dynamics model; estimating a tire force based on vehicle dynamics; estimating the vehicle speed by using an unscented Kalman filtering algorithm based on singular value decomposition; a tire model based on the slip speed is constructed, and normalized tire force is calculated according to the tire model; estimating a road adhesion coefficient by using an unscented Kalman filtering algorithm based on singular value decomposition; according to the self-adaptive slip speed tire model provided by the invention, the problem of denominator singularity of a current slip rate-based tire model at a low speed and the limitation of a fixed stiffness parameter are overcome, so that the estimation precision and the response speed of the road adhesion coefficient are improved.

A hybrid electric gas turbine engine two speed transmission for a low spool drive including an accessory gearbox in operative communication with a low speed spool motor-generator; a transmission in operative communication with the accessory gearbox and the low speed spool motor-generator; a low speed spool angled gearbox in operative communication with the transmission; and a low speed spool in operative communication with the low speed spool angled gearbox.

The invention relates to a motor filtering speed measurement method based on an FPGA, and belongs to the technical field of motor speed measurement. The filtering speed measurement method comprises the following steps: detecting rotation of a motor through a Hall encoder and outputting a pulse signal, outputting the pulse signal to a digital quantity input interface of an FPGA (Field Programmable Gate Array), and realizing a filtering speed measurement algorithm in the FPGA in a hardware form; and performing data operation processing on the pulse signal by using an FPGA based on a filtering speed measurement algorithm to realize measurement of the rotating speed of the motor. Compared with a speed measurement method in the prior art, the method has the advantages that the FPGA is combined with a filtering speed measurement algorithm, so that the rotation speed of the motor can be measured, the problem of low speed measurement precision of the motor in an unstable state can be effectively solved, the anti-interference capability of motor speed measurement can be improved, and the response speed of a speed measurement system can be increased.

The invention provides an aircraft ground steering system and an aircraft ground steering control method, which can realize steering and runway separation of an aircraft under a low-speed condition even if a front wheel turning system cannot work normally, and can inhibit or avoid additional weight increase. The aircraft ground steering system comprises a turning hand wheel assembly used for controlling a front wheel turning system to achieve steering of an aircraft when the aircraft slides on the ground at a low speed; the brake system comprises a brake control part, and the brake control part is used for controlling the brake pressure of the left main undercarriage wheel and the brake pressure of the right main undercarriage wheel; and a standby turning control unit capable of switching to a standby mode in which the brake pressure of the left main landing gear wheel and the brake pressure of the right main landing gear wheel are controlled via a brake control unit according to the angle of the hand wheel of the turning hand wheel assembly operated by a pilot.

The invention relates to a sealing structure, in particular to a combined sealing structure for an output shaft of a marine gearbox. The problem that an existing sealing component can cause leakage under the conditions that an output shaft is static, low in speed, large in lubricating oil amount, too large in oil pressure and the like is solved. A three-stage combined sealing structure is formed by the oil slinger, the labyrinth sealing ring and the lip-shaped sealing assembly. The oil slinger arranged on the output shaft is simple in structure, convenient to transform and good in economical efficiency. The labyrinth sealing ring not only can meet the sealing requirement of a rotating part, but also has self-adaptive flexural deflection, and can be automatically adjusted in a limited manner, so that a good sealing effect is achieved. The lip-shaped sealing assembly structurally achieves the bidirectional sealing effect, internal lubricating oil can be sealed, and water, dust, silt and other external impurities are prevented from entering the gearbox. Through the application of the combined sealing structure, leakage is reduced step by step. The invention belongs to the technical field of gearbox sealing.

The invention belongs to the technical field of traffic intelligent perception, and particularly relates to a road area traffic perception and intervention low-speed operation vehicle collision early warning system and method, and the system comprises a data collection module, a data transmission module, a data processing module, a collision risk judgment module and an early warning information issuing module. Data used by the method are collected data of millimeter wave radar and camera detection equipment installed on a movable device, the method is convenient and rapid to use, real-time radar data is adopted, the method has the characteristics of high detection precision and high detection speed, real-time video data is adopted, the method has the characteristics of light weight and low deployment cost, and the method is suitable for popularization and application. And real-time sensing of vehicle position and size information, weather information and personnel position information can be realized through the edge calculation unit. And the constructor out-of-bound early warning module can judge the position information of the constructors according to the outer contour of the construction operation area and perform early warning prompt on the constructors exceeding the construction operation area, so that the possible interference of the constructors on traffic operation is reduced.

The invention discloses a suspension pitching cooperative control system and method combining dynamic vertical force distribution and multi-mode braking, and particularly relates to the field of vehicle suspensions. Meanwhile, the braking torque distribution unit and the suspension system are controlled in real time by defining a state machine; vehicle low-speed target braking torque and tire vertical force are calculated through the expected deceleration and correspondingly input into a braking torque distribution unit and a four-degree-of-freedom suspension model; converting the four-degree-of-freedom suspension model into a state-space equation and discretizing the state-space equation to obtain a prediction model, and further deriving a state prediction equation of the future N steps; designing a cost function comprising a state quantity weight matrix Q, an input quantity weight matrix R and a state final value weight matrix F, substituting a prediction state into the cost function to obtain an optimal input sequence, dynamically adjusting suspension rigidity, damping and a braking force distribution strategy, and correcting a control instruction in real time by using closed-loop feedback of a vehicle body attitude sensor, so as to improve the stability of a vehicle body. And the suspension pitching control is realized.

The invention discloses a clutch mechanism and an unmanned aerial vehicle. The clutch mechanism comprises a shell; the connecting piece is arranged in the shell and used for being connected with an engine; the first rotor is provided with an inner cavity, and the first rotor is rotationally arranged in the shell and used for being connected with the paddle seat; the second rotor is located in the inner cavity of the first rotor and comprises a base and a plurality of friction plates, the base is connected with the connecting piece, the first ends of the friction plates are movably connected with the base, the second ends are provided with elastic pieces, the elastic pieces are used for making the second ends away from the inner wall of the first rotor, and the second ends can be attached to the inner wall of the first rotor to make the first rotor rotate. By means of the structure, power transmission is kept, and meanwhile it is ensured that the propellers can be kept static in the low-speed and idle-speed states and cannot interfere with a launcher.

The application discloses a highway traffic monitoring system based on unmanned aerial vehicle aerial photography, which comprises a camera arranged on a holder, the holder being arranged on an unmanned aerial vehicle, the unmanned aerial vehicle flying at a low speed above a designated highway lane, and the unmanned aerial vehicle driving towards vehicles on the highway lane; the camera is used for photographing a road surface image of the designated highway lane based on the unmanned aerial vehicle and sending the road surface image to an image recognition unit; the image recognition unit recognizes the vehicles in the road surface image; and a road surface monitoring unit determines whether traffic congestion occurs on the designated highway lane based on the positions of the vehicles in adjacent frames.

The invention discloses a distributed steering control method, and belongs to the technical field of vehicle steering. The control method comprises the following steps: acquiring real-time driving data of a vehicle, wherein the real-time driving data comprises a steering wheel angle, a vehicle speed, a road adhesion coefficient and a side slip angle; determining a target Ackerman rate according to the real-time driving data; and controlling the wheels of the vehicle according to the target Ackerman rate and the real-time driving data. According to the real-time driving data of the vehicle, the Ackerman rate is determined, the vehicle turning angle control value is determined according to the Ackerman rate determined in real time and the real-time driving data, and then vehicle wheels are controlled according to the vehicle turning angle control value. Namely, the Ackerman rate of the vehicle in the driving process can adapt to different real-time driving data of the vehicle, the real-time driving data of the vehicle is fully considered, the control stability of the vehicle in key scenes such as high speed, low attachment and low speed is effectively improved, the driving burden of a driver is relieved, and the risk that the vehicle is unstable or even out of control is reduced.

A power tool includes a housing, a motor supported within the housing, a transmission operatively coupled to the motor, the transmission shiftable between a low speed high torque mode and a high speed low torque mode, a spindle configured to receive torque from the motor through the transmission, a speed selector including an actuator movable to shift the transmission between the low speed high torque mode and the high speed low torque mode, a shaft movable in response to movement of the actuator, a magnet coupled to the shaft, and a controller configured to vary an operating speed of the motor based on a detected position of the magnet.

The invention provides a direct-drive control method and device of a vehicle and the vehicle, the method is applied to the technical field of vehicles, and the method comprises the steps that under the condition that the actual vehicle speed of the vehicle is smaller than the preset vehicle speed, if the actual driving mode of the vehicle is a pure electric four-wheel-drive mode, the target driving mode is a direct-drive mode, and the predicted rotating speed of an input shaft is smaller than the first preset rotating speed; if yes, the clutch is controlled to enter a sliding friction state, the sliding friction state of the clutch is maintained according to the target rotating speed of the engine, a first motor is used for generating electricity to charge a power battery, and the rotating speed difference between the actual rotating speed of the engine and the actual rotating speed of an input shaft is calculated in the actual vehicle speed rising process; the clutch is controlled to enter an overpressure state through the rotating speed difference value and the actual rotating speed of the input shaft, the vehicle is controlled to enter a direct drive mode, effective direct drive and stable power transition of an engine can be achieved when the vehicle is at a low speed, meanwhile, the battery charging efficiency is guaranteed, and the driving stability and the overall efficiency of the vehicle within the low-speed range are improved.

The invention relates to a self-vehicle speed estimation method and device, an electronic device and a storage medium, and the method comprises the steps: obtaining trace point data captured by a radar sensor, the trace point data comprising the radial speed and azimuth angle of each target trace point; determining a static target trace point from the target trace points based on the azimuth angle of each target trace point; based on the radial speed and the azimuth angle of the stationary target plot, calculating a target ground speed corresponding to each stationary target plot; dividing a speed interval for the target ground speed based on a preset step length; based on the trace point distribution feature information of the static target trace point in each target speed interval, determining a target effective interval; and calculating the average value of the radial speed of each static target trace point in the target effective interval to obtain a self-vehicle speed estimation value. According to the invention, the problem that the precision of the vehicle speed calculated through the millimeter wave radar is insufficient when the vehicle runs at a low speed is solved, and the low-speed vehicle high-precision estimation independent of external vehicle speed input is realized.

The invention relates to the field of Stirling engines, and provides a Stirling engine oil-free lubrication cylinder sleeve and a Stirling engine, the Stirling engine oil-free lubrication cylinder sleeve comprises a cylinder sleeve body, and the inner hole wall of the cylinder sleeve body is divided into a high-speed section and low-speed sections located on the two sides of the high-speed section in the axial direction of the cylinder sleeve body; continuous net-shaped textures are arranged on the surface of the inner wall of the high-speed section, pit textures distributed in an array mode are arranged on the surface of the inner wall of the low-speed section, and the net-shaped textures and the pit textures form gradient surface textures in the axial direction of the cylinder sleeve body. The gradient surface texture is arranged on the inner surface of the cylinder sleeve according to the reciprocating speed characteristic of a piston, the high-speed section strengthens gas dynamic pressure bearing through the net-shaped texture, the low-speed section optimizes adhesion resistance and abrasive dust storage through the pit texture, the gas lubrication potential is fully released, friction reduction and service life prolonging of a dynamic sealing friction pair are achieved, and the service life is prolonged. The problems that a single surface structure of a traditional cylinder sleeve cannot be matched with the reciprocating speed difference of a piston, and the gas lubrication effect is insufficient are solved.

The invention provides a bumper assembly low-speed collision test system and method, and the system comprises a mobile barrier trolley, a universal rapid installation clamp, a multi-sensor integrated measurement module, and a data collection and processing system, and can adapt to different bumper assemblies to be tested through the universal rapid installation clamp, simulates the real collision process, and improves the test precision. In the process that the traction system drives the movable barrier trolley to move along the track to conduct the collision test, the multi-sensor integrated measurement module can collect collision data and draw a data curve, and the accuracy of the collision test result is improved. And then the data acquisition and processing system scores the maintenance economy, the energy absorption efficiency, the passenger protectiveness and the structural integrity according to the collision data and the data curve, grades the collision test result according to the scoring result, and finally can output a depth test report containing rating and improvement suggestions. The method is used for supporting and improving the design and optimization capability of the bumper assembly.

The utility model relates to the technical field of full-vector drive-by-wire chassis, in particular to a full-vector drive-by-wire chassis steering device. Comprising a dual-redundancy full-vector drive-by-wire steering gear and a dual-wishbone independent suspension mechanism, the dual-redundancy full-vector drive-by-wire steering gear comprises a steering gear body, the steering gear body is provided with a gear mechanism, a turbine worm mechanism, a rack mechanism and a rack output shaft tube, and the gear mechanism and the turbine worm mechanism are arranged in a parallel structure. The turbine worm mechanism comprises a turbine and a worm, and the gear mechanisms on the two sides are correspondingly connected with steering motors respectively; the double-wishbone independent suspension mechanism is of a bilateral symmetry structure and comprises an upper wishbone, a lower wishbone, a full vector steering knuckle, a shock absorber, a suspension parameter adjusting device, a balance rod and a steering knuckle arm. According to the utility model, the independent steering of each wheel at a low speed can be ensured, and the stability, the safety and the reliability of the vehicle during high-speed driving can also be ensured.

The present invention is an apparatus for moderating the speed of a vehicle. A non-Newtonian fluid is encased in a durable, flexible enclosure that is positioned in a traffic area. An example embodiment is a form that is higher than a road surface. A vehicle approaching the apparatus at a low speed imparts an impact force below the threshold, causing the fluid to remain in its liquid state. This allows the vehicle's wheels to depress into the apparatus, thereby passing over the apparatus with little to no resistance. A vehicle approaching the apparatus at a high speed imparts an impact force above the threshold, causing the fluid to behave as a solid, thus impeding or stopping the vehicle's movement. Another embodiment is lower than a road surface and is configured to trap slow moving vehicles while allowing fast moving vehicles to pass.

To improve power efficiency of a synchronous motor in a wide speed range from a low speed to a high speed.SOLUTION: In a pole-number switching method, the current value of AC current supplied to an armature is reduced at low speed by increasing the number of poles and increasing the torque multiplier of the electric motor, thereby reducing copper loss, and loss at high-speed rotation (mainly iron loss) is reduced at high speed by decreasing the number of poles and lowering the voltage and frequency of the AC current supplied to the armature. Furthermore, a further power-efficiency improvement effect is provided by connecting the circuit such that, during driving of the electric motor, inverter power-supply current of an armature winding becomes a power supply for a field winding, and such that, during regenerative braking, current generated from the armature winding is regenerated to a battery efficiently.SELECTED DRAWING: Figure 2

A sensor system for a vehicle low speed parking maneuver, which includes a first curb with a groove, and a plurality of proximity sensors contained within the groove, the plurality of sensors to detect a vehicle tire within a determined distance from the first curb during a vehicle parking maneuver, and the plurality of sensors wirelessly transmit detection data to a controller for parking validation.