81 results about "Droop speed control" patented technology

A pumping system for moving water of a swimming pool includes a water pump, an infinitely variable speed motor, and an arrangement for operating the motor. In one example, the pumping system includes a memory configured to store a plurality of retained speed values, an arrangement for providing a plurality of retained speed values to the memory, and an arrangement for reading a selected one of the plurality of retained speed values from the memory. In addition or alternatively, the pumping system includes a storage medium for digitally storing a plurality of pre-established motor speed values and an arrangement for receiving input from a user to select one of the pre-established motor speeds. In addition or alternatively, the pumping system further includes an arrangement for restarting operation of the motor at a previously selected speed value when power supplied to the motor is interrupted during operation of the motor. A method for controlling the pumping system is also provided.

A wastewater pumping system includes a centrifugal pump operatively connected to an electric motor via a coupling. The speed of the electric motor is automatically varied responsive to the head or load realized by the pump of the system as it varies with the composition of the slurry mixture. A variable frequency drive is operatively connected to the motor and the electrical power supply that affects a shift or change in electrical frequency delivered to the electrical motor so that the speed of the motor and consequently the pump is varied. This allows the electrical power deliver to the system to remain substantially unchanged for varying loads realized by the pump.

The invention relates to a grid connection presynchronization control method of a microgrid inverter based on droop control. When the microgrid operates in island, as a voltage source type inverter which functions as the support in the microgrid works in accordance with droop characteristic, a microgrid voltage has a deviation from a high power grid voltage; and the problem of synchronization between the microgrid voltage and the high power grid voltage during the grid connection is the key to realize smooth switchover. The grid connection presynchronization control method provided by the invention comprises the following steps: obtaining frequency and phase position information of the high power grid voltage through a three phase software phase-locked loop (SPLL); carrying out dq (Direct Quadrate) conversion to an output voltage of the inverter based on a power grid voltage phase obtained from the locked phase; subsequently carrying out PI (Physical Impairment) regulation on a q-axis component; overlapping a synchronization angle frequency output by a PI regulator with an angle frequency generated by the droop control to be used as a reference angle frequency of the output voltage of the inverter; and finally realizing the tracking and synchronization of the output voltage of the microgrid inverter to the high power grid voltage through the closed-loop control. The impact current during the grid connection is avoided effectively.

The invention discloses a micro-grid multi-inverter parallel voltage control method for droop control of robust power. The method comprises the following steps of: specific to each inverter in a micro-grid, computing and synthesizing an inverter output reference voltage by adopting a robust power droop controller; and introducing virtual complex impedance containing a resistance component and an inductive impedance component, and keeping inverter output impedance in a pure resistance state under a power frequency condition by adopting a multi-loop voltage control method based on virtual impedance and quasi-resonance PR (Proportional-Resonant) control, thereby realizing micro-grid multi-inverter parallel running and power equation, wherein the robustness of a micro-grid parallel system on numeric value computing errors, parameter drift, noise interference and the like is enhanced. Due to the adoption of the method, the defects of larger loop current of a parallel system, non-uniform power distribution and the like caused by the inductivity of the impedance output by inverters in the conventional droop method are overcome; and the method is suitable for multi-grid parallel uniform current control in a low-voltage micro-grid.

The invention discloses a variable speed-variable pitch combined control method of a variable speed constant-frequency wind turbine generator. According to the control method, an optimal rotating speed estimated value and a rotating speed reference value are introduced to respectively serve as reference quantities of rotating speed control and variable pitch control. A rotating speed PID controller performs torque command regulation according to the deviation of the optimal rotating speed estimated value and the rated rotating speed of the wind turbine generator, a variable pitch PID controller performs pitch angle command regulation according to the deviation of the rotating speed reference value and the rated rotating speed of the wind turbine generator, decoupling control between rotating speed control and variable pitch control is achieved, and interference between rotating speed control and variable pitch control is avoided. When wind speed fluctuates nearby the rated value and pneumatic power captured by the wind turbine generator is larger than rated power, the rotating speed reference value corresponding to a pneumatic power estimated value is larger than the rated rotating speed of the wind turbine generator, the variable pitch PID controller regulates a pitch angle command before a torque command output by the rotating speed PID controller reaches the rated value, and variable speed-variable pitch combined control is achieved in advance to control rotating speed of the wind turbine generator and overshooting of output power.

A current sensor is installed in a generator set to measure the current being delivered from the generator set to a refrigeration unit. A control is responsive to the current transformer to reduce the speed of the drive engine to a lower speed when the current being delivered to the refrigeration unit is determined to be below a predetermined higher level. Provision is made to override the system when the sensed current is determined to be transient caused or in the event that ambient temperature is determined to be above a predetermined temperature threshold.

The invention belongs to the technical field of droop control of DC converters, relates to a droop control method of a DC converter with a function of secondary adjustment of adaptive impedance, and aims to solve the problems that distributed generating unit cable impedance difference causes poor droop current homogenization effect to the DC distributed power supply system and the DC micro grid based on droop control and the parallel DC converters is low in steady state and dynamic current homogenization precision. The method has the advantages that the steady state and dynamic current homogenization precision of the parallel DC converters in the distributed DC power supply system and the DC micro grid based on droop control is improved; parameters, such as voltage, current and droop coefficient, of the parallel converters are transmitted in real time through low-speed communication, the droop coefficient is adjusted in self-controllers of the parallel converters, and finally external characteristic impedances of the parallel converters are equalized; droop curves are subjected to shifting adjustment, and bus voltage drop caused by droop control is improved.

A motor-generator is feedback-controlled by adopting the rotation speed information from a resolver when the rotation speed of a motor-generator is low, and by adopting the rotation speed information from a north marker when the rotation speed thereof is high. If the gradient of change in the rotation speed thereof based on the presently adopted rotation speed information is greater than or equal to a predetermined value, the rotation speed information switching operation is prohibited to prevent the shift shock during the ratio shifting operation of a reduction mechanism. That is, in a construction in which the rotation speed of the motor-generator can be detected via the resolver and the north marker, the power output device capable of properly performing the rotation speed control of the motor-generator and the like by making proper the timing at which the rotation speed information adopted for the control is switched.

Active droop current sharing among power supply units may regulate output currents of power supply units supplying shared current to a common load. The regulation may employ a combination of droop control and active current control. The shared current may be regulated such that each power supply unit provides a substantially equal share of the total current supplied. A current difference between two power supplies may be regulated to be within a desired maximum threshold for current difference.

The invention discloses an interconnection line-free secondary control method of parallel inverters in a micro grid and belongs to the coordinated control field of parallel inverters in a micro grid. According to the method of the invention, the inverters monitor the frequency and voltage amplitude of a system in real time; when the deviation of the frequency or voltage is large, the inverters estimate the power requirement of a load and load power which is required to be borne by the inverters in an on-line manner according to monitored frequency and voltage information, and then calculate new droop characteristics; and therefore, the inverters can automatically adjust the deviation of the droop characteristics of the inverters, and the output power of the inverters can be changed, and the recovery of the frequency and voltage amplitude of the system can be facilitated, and the deviation of the frequency and voltage amplitude caused by droop control can be effectively eliminated. The method does not depend on communication between the inverters. With the method adopted, accurate control on the frequency and voltage amplitude can be realized, and at the same time, equipartition of load power, which is in direct proportion to the capacity of the inverters, can be obtained between the inverters, and excellent references can be provided for engineering application.

The invention discloses an adaptive multi slope droop control system and an adaptive multi-slope droop control method for a direct current microgrid. Aiming at the problem that in the direct current microgrid, the system average current is contradictory with busbar voltage deviation in distributed microsource parallel operation, a load current is divided into three areas including a light load area, a rate load area and a heavy load area, and then multi slope droop control (MSDC) is implemented for the different load areas, to focus on improvement of system average current performance and busbar voltage deviation of the rate load area and the heavy load area. An MSDC converter output characteristic curve is different from a traditional constant droop output characteristic, the light load area, the rate load area and the heavy load area in the load area can be flexibly distributed according to system requirements on average current error and busbar voltage deviation, and an adaptive adjustment capacity to the load is provided, so that optimal configuration and design for the droop characteristic within a relatively wide load range can be achieved.

A method of starting a wind turbine generator of any type of polyphase AC machine, including, but not limited to, brushless DC or permanent magnet machines is disclosed. The machine starts from a dead stop or from low speed operation and is accelerated to the cut in speed for power production. The start-up is realized utilizing the common set of electrical conductors and the power converter also used for capturing the generated power. Under initial operation, the power converter executes a PWM modulation technique to drive the machine. Periodically, the PWM modulation is stopped to read the electrical position of the generator.

In a frequency control system, a system controller assigns load-specific threshold frequencies to electrical loads of a fleet of electrical loads. Load controllers perform load monitoring and control operations for controlled electrical loads of the fleet including (i) comparing a measurement of the electrical frequency with the threshold frequency assigned to the controlled electrical load and (ii) operating the controlled electrical load based on the comparison. For example, each load controller may perform operation (ii) by turning the controlled electrical load on if the measurement of the electrical frequency is greater than the threshold frequency assigned to the controlled electrical load, and turning the controlled electrical load off if the measurement of the electrical frequency is less than the threshold frequency assigned to the controlled electrical load. The threshold frequencies may be assigned based on State of Charge (SOC) values for the loads.

A method for the closed-loop speed control of an internal combustion engine-generator unit with a coupling, in which method, when the engagement of the coupling is detected, a change is made from a first set of parameters to a second set of parameters. In the second set of parameters, a second run-up ramp is set, which determines the presetting of the set speed, and second controller parameters are set as the determining factors for computing controller components of a speed controller.

A change-speed control system is provided for a utility vehicle having a stepless change-speed apparatus for speed-changing an engine output and transmitting the speed-changed output to a traveling unit. The system includes an engine speed governor for adjusting speed of the engine, an accelerator controller and a change-speed control linkage device for providing operative displacements in the stepless change-speed apparatus and the engine speed governor in association with an operation of the accelerator controller. The change-speed control linkage device sets an operation amount for the stepless change-speed apparatus and an operation amount for the engine speed governor in correlation with the operation amount of the accelerator controller, such that an acceleration ratio for the engine speed is greater than an acceleration ratio for the stepless change-speed apparatus until the engine reaches a predetermined speed and also the stepless change-speed apparatus reaches a predetermined speed.

To suppress vibration and noises generated in a low speed rotation zone and secure a wide low speed rotation zone by performing optimum torque control even under a condition that a load of a compressor is low. A speed control part 20, an inverter output part 22 and a drive circuit 14 controls drive voltage applied to a motor driving a compressor. In parallel, a position detection part 16 and a torque control part 18 estimate a load of the compressor. The torque control part 18 and an output voltage synthesis part 21 regulates drive voltage based on the estimated load and controls fluctuation of rotary acceleration of a rotary mechanism of the compressor.

The invention provides a rotation speed control system and method of a CPU (Central Processing Unit) fan. The method comprises the steps of: obtaining a system environment temperature by using a temperature sensor, adjusting a fan rotation speed to be a first rotation speed and obtaining a first working temperature of the CPU at the first rotation speed; figuring out a first optimization temperature of the CPU at the first rotation speed; adjusting the fan rotation speed to be a second rotation speed and obtaining a second working temperature of the CPU at the second rotation speed; figuring out a second optimization temperature of the CPU at the second rotation speed; figuring out a temperature difference value according to the first optimization temperature and the second optimization temperature; judging whether the temperature difference value is less than a preset temperature parameter or not; and controlling the rotation speed of the CPU fan within an optimal rotation speed range while the temperature difference value is less than the temperature parameter. By implementing the invention, a heat radiation effect and fan noise of an electronic device system can be balanced to optimize the heat radiation effect of the system and reduce the fan noise.

The invention discloses a DC micro-grid system and a variable droop coefficient control method thereof. The DC micro-grid system comprises three converter units, two resistive loads, a TMS320F28335 controller and its accessory circuit. The variable droop coefficient control method, compared with the conventional droop control, incorporates voltage recovery control and droop coefficient correctioncontrol. The method performs voltage compensation control on the output voltage minimum value, achieves a control objective that the converter output voltage minimum value is the same as a set reference value, and solves the large deviation of the conventional droop control DC bus voltage and the set voltage reference value. The method fixes the droop coefficient of one converter, and obtains thedroop coefficient compensation terms of the remaining converters by the droop coefficient correction control. The droop coefficient reference value is superimposed onto the droop coefficient compensation terms so as to form a corrected droop coefficient. Then the droop control is performed, thereby achieving a control objective that the converters equally distribute the load current under the condition that the line resistances have a large difference, and solving the problem that the shunt accuracy decreases when the line resistances of the converters are inconsistent.

The invention discloses a wind turbine generator primary frequency modulation system dynamic response modeling method based on the rotation speed control. The modeling method comprises the steps: solving a small-signal increment delta omega del_ref of a wind turbine generator suboptimum rotor speed omega del_ref according to a suboptimum power track model; solving a small-signal increment delta Pm of the mechanical power Pm according to an aerodynamic model; solving a small-signal increment of a related condition variable according to a speed controller model; solving a small-signal increment delta Tadd of additional electromagnetic torque Tadd according to a primary frequency modulation controller model; solving a small-signal increment delta Pe of the electromagnetic power Pe according to a converter model; solving a small-signal increment delta omega r of a wind turbine generator rotor speed omega r according to a generator electromechanical transient model; establishing a state equation of a rotation speed primary frequency modulation control input output system; constructing a system state space model and solving a system input output transfer function. The modeling method is similar to a double-fed wind turbine generator primary frequency modulation system dynamic modeling method which is described by synchronous generator prime motor-speed controller primary frequency modulation system dynamic response, so that a mathematic description method of the wind turbine generator primary frequency modulation response under the power system frequency disturbance can be obtained.

The invention relates to idle speed control of an engine, and discloses a method for controlling idle speed of an electronically-controlled unit of a motorcycle engine. The method comprises the following steps: determining whether the engine is in an idle speed working condition or not; if so, starting the electronically-controlled unit; determining whether driving condition of an electromagnetic valve is fulfilled or not; if so, waiting for driving and calculating driving time simultaneously; transmitting a calculating result to the electromagnetic valve to drive the electromagnetic valve; checking the driving time to determine whether driving is completed or not; and if not, stopping driving the electromagnetic valve. The invention realizes excellent real-time control by the electronically-controlled unit to ensure that the engine can work at minimum rotating speed normally, and controls air input inside a cylinder based on the best air-fuel ratio to ensure that fuel of the engine can be combusted more sufficiently under the idle speed working condition, thereby reducing content of harmful gases in tail gas emission at this moment, and achieving specified emission standard.

The invention provides an inversion terminal sliding mode control method based on a load torque observer for a permanent magnet synchronous motor (PMSM) speed control system. An extended state observer is used to estimate a load torque in real time, and the real-time estimated load torque is introduced into the output of the speed loop to give a q-axis current to form feedforward compensation so as to enhance the ability of the system to resist load disturbance. Aiming at the perturbation problem of motor parameters in the design of current loop, the idea of high-order terminal sliding mode control is introduced, and the high-order terminal sliding mode control method of d and q currents is designed, so that the current tracks the current given value in the limited time to ensure the stability of the speed control system and achieve robustness to motor parameter perturbation.

The present invention relates to a droop control method in a multi-micro power grid interconnection scene. The method includes the steps as follows: measuring an actual exchange power value among micro power grids; calculating a deviation between the actual exchange power value and a pre-set exchange power value, if the deviation exceeds a pre-set deviation permissible value, the deviation is set as a control reference deviation of the micro power grids; setting a tiny increasing rate of a generating cost according to the control reference deviation, and calculating power modification values of various converters in the micro power grids according to the tiny increasing rate; calculating exchange power planned values of the various converters according to the power modification values, and comparing the exchange power planned values of the various converters with a maximum power permissible value set by the converters, if one exchange power planned value of one converter exceeds the maximum power permissible value set by the converters, correcting the control reference deviation and returning the previous step; otherwise, executing the net step: modifying the droop control reference power of the converters as the maximum power permissible value.

Variable speed drives are utilized in refrigerant systems to operate motors of the system components at varying speeds, typically for the purposes of capacity adjustment, efficiency enhancement, reliability improvement or power consumption limitation. However, variable speed controls are expensive. The present invention offers flexibility to utilize a variable speed drive to provide variable speed functionality between compressor and fans (or other rotating components having electric motors) within a refrigerant system depending on operational and environmental conditions and external load demands. The switching device switches the variable speed drive between component motors as indicated by a control for the refrigerant system.

The invention provides a rotating speed control method, a rotating speed control system and an air conditioner. The rotating speed control method comprises the following steps: detecting a first rotating speed and a first current of a first fan in the air conditioner during working; detecting a second rotating speed and a second current of a second fan in the air conditioner during working; determining a current difference between the first current and the second current, and judging the relation between the current difference and a preset current difference; and adjusting the first rotating speed or the second rotating speed according to the judgment result. By the technical scheme, when the power is imbalanced when the first fan and the second fan work, one of the fans is adjusted to achieve the state of balanced running power of the two fans, and therefore, the service lives of the fans are prolonged.

The invention discloses a frequency injection based DC microgrid power sharing control method and system, which are applied to the technical field of microgrid control, and aim to solve the problem that the power cannot be shared due to the line impedance, and droop control cannot achieve power sharing on the premise of the stable output voltage; and the frequency injection based DC microgrid power sharing control method can achieve power sharing of a plurality of convertors in a DC microgrid. The frequency can allow the voltage droop problem existing in the classical droop control to transferto the frequency, so that in the DC microgrid, the stability of the output voltage is ensured, and the power sharing effect is ensured.

A change-speed control system is provided for a utility vehicle having a stepless change-speed apparatus for speed-changing an engine output and transmitting the speed-changed output to a traveling unit. The system includes an engine speed governor for adjusting speed of the engine, an accelerator controller and a change-speed control linkage device for providing operative displacements in the stepless change-speed apparatus and the engine speed governor in association with an operation of the accelerator controller. The change-speed control linkage device sets an operation amount for the stepless change-speed apparatus and an operation amount for the engine speed governor in correlation with the operation amount of the accelerator controller, such that an acceleration ratio for the engine speed is greater than an acceleration ratio for the stepless change-speed apparatus until the engine reaches a predetermined speed and also the stepless change-speed apparatus reaches a predetermined speed.

The invention discloses a frequency observation method for droop control of a grid-connected inverter, and belongs to the technical field of distributed power generating / micro power grids. The method includes the steps of carrying out Clarke transformation for the three-phase grid voltage, obtaining the voltage value on a two-phase static coordinate system, conducting quadratic differential operation on the value to construct a linear equation group, eliminating negative sequence and second harmonic components by solving the equation, extracting positive sequence components in cooperation with low-pass filtering under a rotating coordinate system calculating real-time grid phase angle accordingly, selecting a shorter calculation window, and fitting the frequency value according to the angle and time sequence in the window by using an improved least squares method. Modified LSM is used to calculate the low-frequency component frequency value in the rotating coordinate system, so as to compensate the phase angle lagging caused by low-pass filtering, and to accurately observe the grid phase angle.

The invention discloses an engineering vehicle and an engine rotating speed control system and method of the vehicle. The engine rotating speed control system of the engineering vehicle comprises a chassis ECU and a controller, wherein the chassis ECU is used for sending a first message including the current torque percentage and receiving a second message including set rotating speed, the controller is used for being in signal connection with the chassis ECU, receiving the first message and calculating the current torque according to the current torque percentage, the set rotating speed corresponding to the current torque is determined according to a preset mapping table of torques corresponding to rotating speeds, and the second message including the set rotating speed is sent to the chassis ECU. The engine rotating speed control system of the engineering vehicle can avoid giant fuel consumption in the low load, saves energy and is simple and reliable.

The invention discloses a wind turbine generator protective control system under various working conditions. The wind turbine generator protective control system is characterized in that a control model of the control system is firstly established according to control characteristics of a wind turbine generator; a rotation speed controller which adopts a transient-state control strategy and a steady-state control strategy to operate in parallel is used for judging which rotation speed protective control method is adopted according to the specific condition of the special working condition; when a power grid is in a steady state, the rotation speed controller under the steady-state control strategy is adopted, so that a fan safely operates under rated rotation speed; when the wind turbine generator operates under a special working condition, rotation speed control under the transient-state control strategy must be automatically switched to, a phenomenon that the wind turbine generator exceeds speed as a result of a special working condition or power of the wind turbine generator sharply increases as a result of voltage fluctuation of the power grid can be restrained by quick response, and input power of the wind turbine generator is reduced to adapt to reduction of output electric energy under faults of the power grid.