7 results about "Capacitor voltage" patented technology

The invention discloses a light emitting diode (LED) drive circuit. The LED drive circuit comprises a transformer, a metal oxide semiconductor (MOS) tube, a power adjusting resistor, a direct current buffer circuit, a rectifying circuit and a voltage control circuit. When the voltage of a control end of the voltage control circuit is higher than of the threshold voltage of the MOS tube, breakover of the MOS tube is achieved, a current input by an external power supply passes by a first winding of the transformer, the MOS tube and the power adjusting resistor sequentially, and the rectifying circuit is powered on. When the voltage of the power adjusting resistor is similar to the voltage of a standard end of the voltage control circuit, the MOS tube is cut off, a second winding of the transformer charges a capacitor of the MOS tube through the direct buffer circuit, the rectifying circuit is powered on, and the first winding of the transformer supplies power to LED load through the rectifying circuit. When the capacitor voltage of the MOS tube is higher than the threshold voltage, breakover of the MOS is achieved again. The LED drive circuit can replace a power source to manage an integrated circuit (IC), simplifies the LED drive circuit and reduces the cost.

The invention discloses a modulation and voltage stabilization control method suitable for a single-power binary hybrid cascaded H-bridge multilevel inverter. In modulation, a modulated wave vm obtained through taking an absolute value of a sinusoidal modulated wave vref is compared with triangular carriers vca, vcb', vcr1' and vcr2' and a voltage constant value 2E to obtain five logic pulse signals A, B, R1, R2 and P; the sinusoidal modulated wave vref is compared with zero voltage to obtain a polar pulse signal D; and an optimized PWM drive signal is generated from the logic pulse signals and the polar pulse signal through a drive logic operational circuit. In voltage stabilization control, real-time adjustment is carried out on amplitudes of triangular carriers vcb, vcr1 and vcr2 through a signal obtained through operation of DC side voltage sampling signals Vdc1 and Vdc2 and voltage reference signals Vdc1* and Vdc2* of auxiliary units, thereby achieving voltage stabilization control on the auxiliary units through combining modulation. According to the control method disclosed by the invention, the stability of capacitor voltage can be controlled, output levels and the equivalent switching frequency of output voltage of the inverter can be improved and the output characteristics of a system are improved.

The invention relates to a current source converter driven asynchronous motor torque control method and system, and the method is characterized in that the method comprises the steps: adding the output filtering capacitor voltage of a current source converter into a cost function used for predicting torque control on a pre-constructed current source converter driven asynchronous motor model; and determining an optimal switching vector which minimizes the cost function so as to control the output filter capacitor voltage and the output torque of the current source type converter, and carrying out resonance suppression on an LC network formed by the output filter capacitor of the current source type converter and the stator inductance of the asynchronous motor. According to the method, energy oscillation between the filter capacitor and the stator inductor can be effectively suppressed, electromagnetic torque pulsation is reduced, meanwhile, the method has excellent steady-state performance and rapid torque dynamic response, and the method can be widely applied to the field of asynchronous motor torque control.