53results about How to "Improve current control accuracy" patented technology

The invention relates to a constant-current control method of a power switch type LED drive circuit and a circuit thereof. The method comprises the following steps of: setting a reference voltage value corresponding to the constant average current value of an LED lamp group and the sustainable turn-off time T2 of a power switch; opening the power switch to acquire an induced voltage corresponding to the working current of the LED lamp group, and comparing the induced voltage and the reference voltage value; accumulating the sustainable opening time Ta of the power switch since the power switch is opened until the induced voltage reaches the reference voltage value; accumulating the sustainable opening time Tb of the power switch since the induced voltage of the LED lamp group reaches the induced voltage value, when Tb is equal to Ta, turning off the power switch; and since the power switch is turned off, timing the sustainable turn-off time of the power switch, and after the set sustainable turn-off time T2 is reached, opening the power switch. The invention realizes the direct control on average current and improves the control precision on the current.

The invention discloses a transversal magnetic flux variable-reluctance permanent magnet motor which relates to the field of a motor and solves the problems of complicated secondary structure and low reliability and current control accuracy. The secondary structure comprises a secondary iron core. The primary structure at least comprises a phase unit. Each phase unit consists of a phase unit iron core, a phase unit winding and a permanent magnet. The phase unit core consists of a plurality of iron core units and is provided with a sprocket hole. The sprocket hole is formed by stacking gear slots of the iron core units. A permanent magnet is arranged on the sprocket of each iron core units, and the magnetic field directions of the magnets on sprockets of adjacent iron core units are opposite to each other. A coil is wound into a one-phase phase unit winding through the gear hole of the phase unit core. The motor can be used as a motor and also can be used as a generator. The permanent magnet of the motor is arranged on the gear of the core unit, therefore the secondary structure has simple structure and high reliability. The vortex loss of the motor is reduced, the motor efficiency is enhanced, the control accuracy of the current is high, and the motor is easy to modularize.

The invention provides a current control method for a three-phase rectifying device in order to solve the problems of low current precision control and current waveform distortions in the prior art and modify a PI (potential intensity) controller to subject each phase point of grid current to PI adjustment. An attenuation coefficient K is used for attenuation of error values to enable previous accumulated errors to be attenuated along with time. According to a test that the magnitude of errors nearby the current grid cycle plays a leading role and current electric current can better track expected current, the current control method has the advantages that defects in the traditional methods can be effectively overcome, current control precision is improved, and the power factor of the three-phase rectifying device can be further improved while harmonic component is reduced.

The invention discloses a bending fretting fatigue test device for a dropper of a high-speed railway catenary, which comprises a dropper fixing end, a force compensating end, a fatigue load loading part and a data acquisition and processing unit. One end of a dropper sample is fixed on a support of the fixing end, and the other end is fixed on a support of the force compensating end. A pre-tightening force is applied to the dropper by a force compensating spring. The middle part of the dropper is connected to a fatigue test machine through a loading rod. During the whole test, the bending fretting fatigue test of the dropper with variable parameters and multiple working conditions is carried out by controlling the fatigue test machine after the pressure of the fixing end and the pre-tightening force of the dropper are set.

The invention discloses a current loop delay compensation method for a three-phase permanent magnet synchronous motor driving system. The method comprises steps that a d-q axis stator current of a next period based on a motor model is predicted, and the d-q axis stator current is taken as a PI regulator feedback value for calculation to obtain a stator voltage reference value; aiming at the influence of motor parameter change on prediction precision, the prediction model is further corrected, when actual parameters are inconsistent with motor parameter nominal values, an error voltage item inthe model plays a role in correcting a current prediction value. The method is advantaged in that hardware configuration does not need to be changed or extra logic devices do not need to be added, themethod is simple in operation, low in cost, simple to implement and easy to expand, weakens the limitation of digital delay on the adjustment speed of the current loop, accelerates the current tracking characteristic, still ensures higher control precision even under the condition of larger motor parameter change, and is suitable for permanent magnet synchronous motor driving occasions with higher requirements on dynamic tracking and control precision.

The invention discloses a grid-connected converter forecast control system with voltage compensation, and also discloses a grid-connected converter forecast control method having voltage compensation.The grid-connected converter forecast control method having voltage compensation comprises the steps of firstly, estimating a grid-connected converter power according to energy change of a capacitance electric field, calculating current changing quantity of an inductor according to the energy changing quantity of the capacitance electric field, and forecasting an instruction current; secondly, designing compensation virtual capacitance according to the energy change of the capacitance electric field, and compensating a DC bus voltage under disturbance; and finally, building a linear control relation between the DC bus voltage and the inductor current. By the grid-connected converter forecast control method, the problems that bidirectional flowing of power cannot be achieved, parameter adjustment exists and the system parameter influence is large due to low inertia and poor disturbance-resistant capability of a DC microgrid and control of a grid-connected converter in the prior art aresolved.

The invention discloses an electro-hydraulic proportional valve control pump/motor hydraulic power assisted system of an electric automobile, which comprises a hydraulic drive circuit, a compound brake system and an electric controller. The hydraulic drive circuit comprises a hydraulic pump/motor, a high-pressure accumulator, a low-pressure accumulator, an electromagnetic directional valve, an electric-hydraulic proportional pressure reducing valve and the like. The brake system comprises a brake pedal, a brake master cylinder, a direct-control sequence valve, a displacement sensor and the like. The hydraulic pump/motor is coupled with a power motor and a drive axle through a transfer case. When brake is performed, the hydraulic pump is driven by the inertia of the automobile to prefill the high-pressure accumulator, and a brake force is generated on the automobile by the drive torque of the pump. When emergency brake is performed, high-pressure oil is exported by the brake master cylinder to enter a brake cylinder, and the brake force is generated by the brake cylinder and the hydraulic pump together. When the automobile starts or is accelerated, if the current of the motor is out of limit, torque is output by the hydraulic motor to assist the motor in driving the automobile, the current of the motor is reduced, the discharge rate of a power battery is reduced, and the service life of the battery is prolonged.

The invention discloses a filament current control method and device. The method includes the following steps: acquiring a current filament current value; determining a current range in which the current filament current value is located; determining a corresponding relationship between the corresponding filament current and the control current according to the current range; and determining the current control current according to the current filament current value and the corresponding relationship. Thereby, the problem of large filament current control errors caused by the nonlinear characteristics of a filament transformer can be solved.

The invention discloses a silicon carbide based high-power low-voltage large-current-output direct-current power supply which comprises an input plug P1, a three-phase EMI (electro-magnetic interference) filter F1, a three-phase air switch K1, a phase-loss detection board B1, a three-phase rectification board B2, a direct-current busbar processing board B3 and a phase-shifting full-bridge board B4. Silicon carbide devices of the power supply are high in switching frequency, low in switching loss, low in conduction resistance R and low in conduction loss, and system efficiency is greatly improved; power density of the power supply is greatly increased by the aid of the silicon carbide devices, a sampling current hall sensor is placed in the middle of four direct-current filter capacitors ina direct-current and output-current sampling circuit, interference value in current sampling can be greatly reduced, and current control accuracy is improved; in addition, in multi-module parallel application, a fuse protector is serially connected to the output side of the circuit so as to prevent the situation that a certain module is infused with large current by other modules when damaged.

The invention discloses a multi-phase interleaving parallel DC-DC converter output current control method and system. The method comprises the steps of: setting interruption frequency fi=N*fs, wherein fs is the switching frequency; setting the triangular carrier frequency of a pulse width modulation register PWM to be fs, employing a counting mode adopting increase and decrease counting, and setting triangular carrier phases to be sequentially lagged by 360 degrees/N. The method further comprises the following steps of: S1, when triggering interruption occurs, reading current information of N-phase bridge arms, and calculating a duty ratio of a power switch tube of an Sth-phase bridge arm when the current of the Sth-phase bridge arm is just the average value current; S2, converting the duty ratio into a PWM signal; and S3, driving a power switch tube of the Sth-phase bridge arm by using the generated PWM signal. The system comprises a calculation module, a digital control module and a driving module, wherein the driving module is used for generating PWM signals and sequentially driving the power switch tubes of the N-phase bridge arms. According to the multi-phase interleaving parallel DC-DC converter output current control method, the problem of poor current control effect caused by relatively large current ripples of a multi-phase interleaving parallel DC-DC converter can be solved, meanwhile, good current sharing among phases can be realized, and the current control precision is improved.

The invention discloses a permanent magnet synchronous motor with an interphase uncoupled structure, relating to the field of motors and solving the problem that the control precision of current is influenced because magnetic coupling exists between phases and the defect that stator iron loss is larger because a magnetic circuit passed by magnetic flow generated by electrifying each group of windings is longer. The phase unit of a stator comprises a plurality of phase armature iron cores and a plurality of phase armature windings, wherein each phase armature iron core comprises 2k iron core units; each phase armature iron core is a phase armature iron core with comprises 2k iron core units and has a tooth hole; the tooth hole is formed by superposing tooth slots; the two teeth of each iron core unit are arranged along the axial direction; a magnet yoke section is connected between the two teeth; 2k iron core units are sequentially arranged in a housing case at equal intervals along the peripheral direction; and coils are wounded into single-phase armature windings by tooth holes. The motor has im phase units when being an m-phase motor, and the included angle between the axes of two adjacent phase armature windings is an electrical angle of [(j-1)+(1/m)]*180 degrees. The permanent magnet synchronous motor not only can be used as an electromotor but also can be used as a generator.

The invention discloses an application method of a wireless discharging device of an accumulator cell, which is realized by the following steps: (1) merging a temporary accumulator cell group into a running direct current (DC) loop, retreating an accumulator cell group in an original DC loop from running and using the accumulator cell group in an original DC loop as an accumulator cell group to bedetected; (2) accessing the wireless discharging device to the accumulator cell group to be detected; (3) setting discharging parameters of the wireless discharging device, detecting wire connectionsand patrolling data; (4) discharging and charging the accumulator cell group to be detected for a circle; (5) judging whether the accumulator cell group to be detected is qualified or not according to a discharging result obtained in step (4); if the accumulator cell group to be detected is qualified, turning to step (6); if not, turning to step (4); and (6) recovering original wire connection manner. The invention has the advantages of high accuracy of current control, continuously adjustable discharging current of accumulator cells, error within the range of 0.5 A, simple wire connection, small size for carrying conveniently, diverse operation modes, and clearer discharging data for comparing data conveniently.

The invention relates to a high-power linear electromagnetic acceleration system and belongs to the field of motors. The driving system of a conventional high-power linear electromagnetic accelerationsystem has a great difficulty in dynamic current-sharing control and does not have a fault-tolerant function. The high-power linear electromagnetic acceleration system is characterized in that coilsin a primary starting region has a large number of series turns, a coil driver has a small output current, a purpose of driving the low-speed section of a linear motor by using a driver with a small current and a high chopping frequency is achieved; coils in a primary terminal region has a small number of series turns and the coil driver has a large output current. When the high-speed section is driven, multiple parallel unit coils are connected in parallel, and each parallel unit coil is driven separately, thereby realizing a purpose of driving a high-power motor in parallel by using small and medium power drivers, avoiding the great difficulty in dynamic current-sharing control caused by parallel connection of multiple power switching devices and achieving the fault tolerance of the driving system.

The invention discloses a fractional order model prediction control method for the power of an electricity-hydrogen hybrid energy storage system, and the method comprises the eight steps: respectively giving equivalent circuit diagrams when a switching tube is switched on and switched off in two working modes of a BOOST circuit and a BUCK circuit, and monitoring an inductive current change process and a capacitor voltage change process. A fractional order calculus algorithm and model prediction control are combined for power control of an electricity-hydrogen combined hybrid energy storage system and device, a fractional order type voltage and current prediction model is obtained, double-loop control is adopted, the switching state of an energy storage converter is selected through prediction output, the output current of the converter relative to a bus is accurately controlled, and the energy storage efficiency is improved. The power fluctuation of distributed power generation is stabilized more finely, and the defects that the response speed of current common double-loop PI control is low, deviation possibly occurs during prediction of existing integer order model prediction control, and the current control precision is low are overcome.

The invention discloses an impulse type linear constant current drive LED circuit and relates to the technical field of LEDs. A half-wave sine wave signal is formed by a bridge rectifier circuit under the control of an alternating-current voltage; a linear constant-current circuit is connected between a positive electrode of the bridge rectifier circuit and a negative electrode of the bridge rectifier circuit and used for outputting constant current according to the half-wave sine wave signal; an LED circuit is connected between an output end of the linear constant-current circuit and the negative electrode of the bridge rectifier circuit; an impulse control circuit is connected with the bridge rectifier circuit and the linear constant-current circuit and used for forming an impulse voltage signal according to the half-wave sine wave signal and outputting the impulse voltage signal to the LED circuit. The LED circuit will be opened when alternating-current sine voltage increases to be higher than the forwarding voltage of the LED circuit and will be closed when the alternating-current sine voltage drops to be approximate to the forwarding voltage of the LED circuit, loss of the part by which sine voltage is higher than the forwarding voltage of the LED circuit is avoided, efficiency of the linear constant-current circuit is improved, the temperature of a power supply is prevented from being too high, and the impulse type linear constant current drive LED circuit has the advantages that the number of devices is small and the circuit is simple.

The invention discloses a microgrid energy storage PCS control system and method. An input end of a three-phase bridge inverter circuit is connected to a storage battery through a direct current EMI filter circuit, and an output end is connected to a three-phase power grid through an LCL filter circuit; a current sensors and a voltage sensor are separately disposed on a three phase line of the output end of the three-phase bridge inverter circuit, and output ends of current transformers and the voltage sensor are separately connected to a control module; the control module receives an externalthree-phase command signal, and according to the received command signals corresponding to each of phases, and a voltage or a current feedback value input by a corresponding phase voltage sensor andcurrent sensor, turn-on or turn-off of each of switching devices in the three-phase bridge inverter circuit is controlled. The control module of the system and the method can achieve phase splitting control of microgrid energy storage, and the power control precision can be improved.