37results about How to "No overcurrent" patented technology

The invention discloses a static off-line parameter identification method of a permanent magnet synchronous motor. The method comprises the steps that firstly, high-frequency rotation voltage with the angular frequency being omegac and the amplitude being urot is input into a stator winding of the permanent magnet synchronous motor, and the amplitude urot of the input voltage is gradually adjusted until the appropriate amplitude of the input high-frequency rotation voltage is found; secondly, the appropriate high-frequency rotation voltage obtained in the first step is input into the stator winding of the permanent magnet synchronous motor for 1000ms, and rotor magnetic pole initial position identification, direct-axis inductance identification and quadrature axis inductance identification are conducted; thirdly, stator resistance is identified through an automatic-adaption two-point type voltammetry in the direction of a rotor magnetic pole obtained through identification in the second step. By the adoption of the static off-line parameter identification method of the permanent magnet synchronous motor, the influence of saturation of a magnetic circuit of a rotor on inductance identification is eliminated, the influence of system non-linear factors on the resistance identification is eliminated, the identification precision is high, the identification time is short, and the rotor can be kept static.

A motor controlling device of electrical fishing line reel capable of preventing the motor loading weighting to prevent the motor being burnout when controlling the speed of the motor at multiple stages, comprising a brake unit , a winding reel sensor detecting the rotating speed of the winding reel; a current detecting portion for detecting the load of the winding reel by current value; an adjusting rod; the rotating speed of the winding reel is divided into high and low grades; the adjusting rod sets the speed upper limit value of each grade; when satisfying the first condition, for the load detected by the load detecting portion, if the motor current maintains time t5 by state of above the first current value less than the maximum current value, the fishing line reel controlling portion degrades the speed of the motor to at least a grade and setting the speed corresponding to the speed upper limit value below the grade as the target speed; comparing the first load setting the target speed and trhe second load after t5, if the second load is more than the second load in set quantity, setting the target speed as a lower speed upper limit value; when satisfying the first speed, the speed of the winding reel is accordant with the target speed.

The invention discloses a method and system for controlling energy of a two-motor controller with a boosting apparatus. The method comprises the following steps: calculating surplus power by virtue of current parameters, ensuring the output power of one motor system of the two-motor controller in priority according to a current working mode and state, feeding back an allowable output torque of the motor system in real time, and ensuring a first motor system and a second motor system not to have over-current phenomenon in an application process. A maximum demand of an entire car can be satisfied, and the maximum output performance of the two-motor controller is played. In addition, current value is adopted for calculation, so that time delay is reduced, and the over-current fault of the two-motor system or the risk of damaging the two-motor system are reduced.

The invention discloses a low-voltage ride-through control method for a grid-connected inverter. Whether a power grid works properly can be judged through a dropping state judgment device, so the method has the advantage of being fast in power grid judgment. In specific configuration, the method includes the steps of controlling a given current calculation module to calculate given current target values of the power grid in a normal working state and in a dropping state, and controlling a feedforward weight calculation module to distribute reasonable specific gravity of different voltage feedforward quantities according to the voltage state of the power grid agine. Consequently, current impact at the instant of voltage drop of the power grid can be restrained, and the recovery rate of the current waveform after voltage drop of the power grid can be increased so that the balance of three-phase current output by the inverter during voltage drop of the power grid can be maintained. Thus, it is guaranteed that the grid-connected inverter is in a fault ride-through state and accords with national standard inverter grid-connection requirements.

The invention discloses a closed loop starting method for a resonant converter. The resonant converter comprises a bridge circuit, a resonant circuit, a transformer, a rectifier circuit, a filter circuit, an input detection circuit, a driving circuit, a peak detection circuit, an output detection circuit and a digital processor, wherein the bridge circuit, the resonant circuit, the transformer, the rectifier circuit and the filter circuit are sequentially connected in series. The input detection circuit is connected to the input end of a resonant transformation device to detect the input voltage and send the input voltage to the digital processor. The driving circuit is connected to the digital processor and converts a PWM signal into the driving level so as to drive the bridge circuit. The peak detection circuit is connected with the resonant circuit, detects the resonant current peak and sends the resonant current peak to the digital processor. The output detection circuit detects the output voltage and the output current and sends the output voltage and the output current to the digital processor. According to the closed loop starting method for the resonant converter, due to the fact that the peak detection circuit detects the resonant current peak, implementation is easy. Closed loop control is conducted on the resonant current peak in the starting process, control is easy, it is ensured that the overcurrent of the resonant converter cannot occur in the starting process, and the starting time is made optimal.

The present invention provides a DC converter station and its control method and control system. The DC converter station control method includes controlling the sending-end converter station by using a constant DC voltage control method; controlling the receiving-end converter station by using an active-reactive power control method. flow station; wherein, wherein, the step of controlling the receiving end converter station using the active-reactive power control method includes: adding an input power adjustment module at the input end of the power loop of active-reactive power control, and the input power adjustment module is connected with the The power loop connection of the active-reactive power control; the input power adjustment module adjusts the input power command of the active-reactive power control according to the grid voltage of the receiving end and the DC bus voltage of the receiving end. With the present invention, reactive power can be continuously provided to the power grid when the voltage drops in the power grid at the receiving end, and no overcurrent phenomenon will occur in the converter station. DC bus voltage, the system can operate stably after the fault is restored.

Disclosed are a control circuit, a control method and a resonant converter. By generating a start control signal that changes correspondingly following the duration of the soft start process as a loop variable, the loop variable presents different changing trends when the resonant current intensity is in different intervals, and then controls the converter so that the The resonant circuit starts. Therefore, according to the actual situation of the resonant circuit current, the change speed of the soft-start loop variable is dynamically adjusted, so that the resonant circuit can start quickly without causing the resonant circuit current to over-current. Resonant circuit design process.

The invention discloses a mixed bipolar DC transmission system. The system comprises a rectification converter station and an inversion converter station which are connected through a DC transmission line, wherein the rectification converter station is formed by two thyristor converters through serial connection, and the serial connection node is grounded; and the inversion converter station is formed by two modular multilevel converters (MMCs) through serial connection, the serial connection node is grounded, and positive and negative ends after serial connection are connected with one-way connection power devices. The system has the advantages of low cost and loss, high reliability and the like of the existing thyristor converter, flexible control of the MMCs, low harmonic, active-reactive power decoupling control, low dependence on an alternating current system and the like; and the system is divided into positive and negative poles, so that operating reliability is strengthened, and the power devices provided with the one-way connection capacity and additionally arranged at outlets of inverters can effectively handle DC faults. The system is suitable for occasions such as high-power long-distance high-voltage DC transmission and island current delivery, provided with broad development space, and worthy of being popularized vigorously.