138 results about "Space vector pwm" patented technology

A space vector pulse-width modulator (SVPWM) and a method implemented by the modulator. A precalculation module accepts Ua and Ub modulation indexes and in response thereto, outputs modified Ua and Ub information; a sector finder has a U module which receives the modified Ua information and outputs a U sector; and a Z module which receives the U sector and the modified Ub information and outputs a Z sector. The U sector and the Z sector are 2-phase control signals for implementing 2-phase modulation. For 3-phase modulation, the SVPWM and method further possess an active vectors calculation module and an assign vectors module which receive the modified Ua and Ub information and the U sector, and which calculate active vectors for 3-phase modulation; a zero vector selector which receives the Z sector and calculates zero vectors for 3-phase modulation; and a PWM counter block which receives the active vectors and zero vectors and outputs 3-phase control signals for implementing 3-phase modulation. The SVPWM and method may have a symmetrical PWM mode, an asymmetrical PWM mode, or both. Advantageously there may also be a rescale and overmodulation module which receives duration information corresponding to the vectors and in response thereto, detects the occurrence of overmodulation. Overmodulation may be detected in response to a negative zero vector time. The module may respond to overmodulation by clamping the zero vector time to zero and rescaling the active vector times to fit within the PWM cycle. The rescaling may restrict a voltage vector to stay within hexagonal boundaries on the space vector plane, while preserving voltage phase.

The invention discloses a voltage-type PWM (pulse-width modulation) rectifier output power control method under a power grid unsymmetrical fault. The technical scheme provided by the invention is characterized in that through the voltage-type PWM rectifier output power control method under the power grid unsymmetrical fault, the output active power and output reactive power which are obtained through calculation are subjected to negation through a band pass filer and a controller; a double frequency offset voltage is obtained through offset voltage calculation, and is offset to the output voltage in traditional vector control; and finally a reference voltage under a two-phase static coordinate system is obtained, a voltage signal generates a switch signal for controlling the power device after being subjected to space vector pulse width modulation, and the output active power and the output reactive power are controlled stably. According to the invention, under the condition of power grid unsymmetrical fault, positive sequence component and negative sequence component in a system are not required to be calculated and resolved; the power pulse of the voltage-type PWM rectifier can be offset directly; the direct-current bus voltage is controlled stably; and the calculation method is simple and can be easily realized.