What are the PWM algorithms commonly used in inverter technology for electric vehicles 5

There are two common control methods for PWM inverter circuits, one is the calculation method; The second is the modulation method. Among them, the modulation method can be divided into two types, one is the asynchronous modulation method; The second is the synchronous modulation method.

The PWM inverter principle is characterized by changing the output voltage, the structure is simple, and the specific application is to control the charging current. PWM pulse width modulation controls the output voltage by changing the pulse width, and controls the output frequency by changing the period. The output frequency can be changed by changing the modulation period of this pulse.

Technical fundamentals

With the development of electronic technology, a variety of PWM technologies have emerged, including: phase voltage control PWM, pulse width PWM method, random PWM, SPWM method, line voltage control PWM, etc., and this paper introduces the pulse width PWM method used in the search section of the nickel-metal hydride battery intelligent charger.

It is to take the pulse train with equal width of each pulse as the PWM waveform, the frequency can be adjusted by changing the period of the pulse train, the voltage can be adjusted by changing the width or duty cycle of the pulse, and the voltage and frequency can be coordinated by using appropriate control methods. The purpose of controlling the charging current can be achieved by adjusting the period of PWM and the duty cycle of PWM.

In this way, the two functions of voltage regulation and frequency modulation are coordinated consistently, and they are independent of the intermediate DC link, so that the regulation speed is accelerated and the dynamic performance is improved. Since the output of equal amplitude pulses only needs to be supplied by a constant DC power supply, the phased rectifier can be replaced by an uncontrollable rectifier, which greatly improves the power factor on the grid side. The PWM inverter can suppress or eliminate the subharmonics of the low footage.

Coupled with the use of self-shut-off devices, the switching frequency is greatly increased, and the output waveform can be very close to the sine wave.

Answer]: The reversible PWM converter is a lead control system that uses the width of the positive and negative pulses of the driving voltage to control the forward and reverse rotation of the motor. When the positive pulse is wide, ton

t 2, then the average value of the output voltage is positive, the motor rotates forward, and vice versa; If the positive and negative pulses are equal, ton

t 2, the average output voltage of the balance excitation is zero, then the motor stops;

The irreversible PWM converter also uses the width and narrowness of the positive and negative pulses of the driving voltage to control the motor, but because the average voltage does not change the polarity, the motor can only work in the first place.

1. 2 quadrants.

1.An output voltage that is fairly close to a sine wave can be obtained.

2.The rectifier circuit uses a diode, which can obtain a power factor close to 1.

3.The circuit structure is simple.

4.The output voltage can be changed by Qi Conghui's control of the width of the output pulse, which accelerates the dynamic response of the frequency conversion process.

At present, the general inverter basically uses PWM control, so let's introduce the principle of PWM control.