PWM rectifier

About: PWM rectifier is a research topic. Over the lifetime, 2254 publications have been published within this topic receiving 25614 citations.

Switch combination changing direct power control method of three-level PWM rectifier

Abstract: The invention discloses a switch combination changing direct power control method of a three-level PWM rectifier. First, instantaneous active power and instantaneous reactive power of a current moment and a next moment are computed, then the instantaneous active power and the instantaneous reactive power are compared with reference active power and reference reactive power, two groups of switch list selecting signals are obtained, the two groups of signals are used, the sector numbers which voltage reference vectors belong to under an alpha-beta coordinate system are combined, a PWM rectifier direct power control switch list is searched, and two three-phase switch combinations are selected. Then, the minimum power pulse of a next cycle is used as a control target, a time distribution factor is obtained by computing, and in one cycle, the output time of the two selected three-phase switch combinations is distributed. According to the method, the phenomenon of overstriking during a power adjusting process can be avoided, and steady-state performance of a three-level PWM rectifier direct power control system is effectively improved.

Study of PWM Rectifier/Inverter for a High Speed Generator Power System

Abstract: The main advantages of the high speed machine are small size and high power density. However, the high speed machine suffers from higher loss density and cooling difficulty due to small cooling area, especially the high frequency harmonic currents produced by the power conversion system increase the loss and temperature of high speed machine. The output high frequency AC power of the high speed PM generator needs to be converted into the AC power with constant frequency and constant voltage using AC/DC/AC converter. The normal AC/DC conversion through diode rectifier will generate harmonic currents in the generator winding which will cause additional losses and increase temperature rise of the generator. How to reduce the harmonic components is an important problem to be solved for the power conversion system. In order to reduce the current harmonics produced by the AC/DC power conversion and meet the requirements on self-starting, a PWM rectifier/inverter with current harmonics repression function is investigated. The mathematical model of PWM Rectifier is established. Space voltage vector phase angle is determined by testing the zero crossing of line voltage, the no-error of current in the stable state is obtained through double closed loop. The simulation results and experimental results show the feasibility of the proposed design structure and control strategy.

Power source higher harmonic restraining equipment

Abstract: PROBLEM TO BE SOLVED: To miniaturize equipment and reduce carrier frequencies. SOLUTION: A phase is divided into sections every 60 degrees by a power source phase section determining part 32. When a phase voltage is positive, one of transistors 224a, 225a, 226a in transistors of a transistor module 22 for 3-phase pulse width modulation(PWM) rectifier circuit in a power source phase, wherein the absolute value of phase voltage in each section becomes maximum is fixed, and controlled in the state of on during the section. When a phase voltage is negative, one of transistors 224b, 225b, 226b is fixed and controlled, in the state of on during the section. As to the two left phase, the control amount due to the difference component between the command value of an input current to the transistor module 22 for the 3-phase PWM rectifier circuit, and the detected value is compared with a triangular wave carrier frequency waveform, and the transistor of each phase is on/off controlled by a PWM control part 34.

Self-checking device of motor short circuit and application method thereof

Abstract: The invention relates to the field of emergency protective circuit devices which react to overcurrents, in particular to a self-checking device of a motor short circuit and an application method thereof. The self-checking device of the motor short circuit includes current sensors (1) and is characterized by further including a motor controller (2), and a microprocessor (21) outputs a three phase pulse signal to a PWM (Pulse Width Modulation) rectifier (22) through a three phase signal line. The application method of the self-checking device of the motor short circuit is characterized in that when a motor (3) stops working, the following steps are performed sequentially: the microprocessor (21) outputs a three phase pulse detection signal to the PWM rectifier (22) through the three phase signal line; and the microprocessor (21) calculates L according to the formula delta I=U0/L*delta t, if L

Quick soft start circuit for three-phase voltage PWM rectifier and control method thereof

Abstract: The invention discloses a quick soft start circuit for a three-phase voltage PWM rectifier and a control method of the quick soft start circuit. The quick soft start circuit comprises a first small capacitor, a second large capacitor, a seventh switching tube and a DSP. The anode of the first small capacitor, the output end of the positive electrode of a three-phase rectifier bridge and the collector electrode of the seventh switching tube are connected together. The cathode of the first small capacitor, the output end of the negative electrode of the three-phase rectifier bridge, the cathode of the second large capacitor and one end of a load are connected together. The emitting electrode of the seventh switching tube, the anode of the second large capacitor and the other end of the load are connected together. The DSP controls the on-off state of the seventh switching tube through a signal output by an IO port. The quick soft start circuit for the three-phase voltage PWM rectifier achieves soft start by charging the second large capacitor in a time-sharing mode. Besides, the start speed is high, the circuit is not provided with a current-limiting resistor, and therefore loss is small in the starting process.