Introduction to TI's three-phase Vienna PFC solution

alan000345

Introduction to TI's three-phase Vienna PFC solution [Copy link]

TI three-phase Vienna PFC is mainly used in electric vehicle chargers, so first take a look at the typical classification and topology of electric vehicle chargers.

The Vienna rectifier is a popular active PFC topology. It has the following features: inherent three-level switching, reduced inductor size requirements, reduced switching frequency losses, stress switching at half the output voltage, and low electromagnetic interference.

Here we use TI's TIDM-1000: PFC 3PH VIENNA system to introduce it. Let's take a look at the overall introduction of this system.

The design concept of Vienna rectifier is shown in the figure below.

Let’s take a look at the basic modules of Vienna rectifier design as shown in the figure below.

It should be noted that in this system, isolated bus voltage sensor is used for the following reasons:

Due to the high power characteristics of the application using Vienna rectifier, isolated voltage sensing is required for the bus voltage.

Since the bus voltage is divided into two capacitors, both need to be measured to enable the bus balancing controller.

Measuring three-phase voltage to neutral in a three-wire system:

The line-to-neutral voltage is a key measurement signal used in control to track the input voltage, but due to application restrictions, a direct neutral point connection may not be available. Therefore, a virtual neutral point is created and used to measure the LN voltage using a star connection of resistors and capacitors. Next, an isolation amplifier can be used to measure the input AC voltage.

There is also a current protection device here, and the protection principle is shown in the figure below.

Introduction to Vienna PFC Control Loop Design

The single-phase model of the Vienna rectifier is as follows,

The single-phase model of the Vienna rectifier can be considered to begin to understand the power topology.

The goal of the controller is to maintain the diode bridge input voltage so that a clean unity power factor current is drawn, as shown in the phasor diagram above.

To achieve this, the duty cycle (D) is controlled so that the bridge input voltage is directly regulated. The PWM modulation scheme is appropriately chosen to achieve this.

The current loop model is introduced as follows:

Let’s take a look at the voltage loop model.

Finally, let’s take a look at the control structure.

Okay, here we only introduce the hardware, the software is the soul, as for the control software, interested friends can download it from the TI official website, study it, I won’t introduce it here.

qwqwqw2088

The current type model is more complicated and has many formulas.

alan000345

qwqwqw2088 posted on 2018-11-29 16:15 The current type model is more complicated and has many formulas

Yes, but TI's PFC Vienna system is very famous. When we did wireless charging, we planned to use their method. The wireless charging of electric vehicles at Oak Ridge National Laboratory in the United States basically uses TI chips.

1316564416

Learned a lesson

alan000345

1316564416 posted on 2018-12-8 16:57 I have learned a lesson

dengguancun

This explanation is still not detailed enough. After reading it, many people still don’t know how to complete product design.