37results about How to "No overcurrent" patented technology

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 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.