Browse Prior Art Database

A DC Capacitor Voltage Balancing SPWM Algorithm Utilized in 3 Levels Vienna Converters

IP.com Disclosure Number: IPCOM000249859D
Publication Date: 2017-Apr-19
Document File: 7 page(s) / 369K

Publishing Venue

The IP.com Prior Art Database

Related People

Lin Ma: AUTHOR [+4]

Abstract

DC bus voltage balancing is a key issue for multi-level converters. Different PWM methods are utilized to balance the DC bus voltage, most of the PWM methods are based on Space Vector Pulse Width Modulation (SVPWM). Usually, the related SVPWM control the DC bus voltage by using different zero sequence vector. However, for the Vienna converter as shown in Fig.1, there are only 3 bi-directional switches needed to be controlled. Using SVPWM will increase the software complexity. This disclosure proposed a DC balancing method based on SPWM through modifying the modulation waveforms.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 45% of the total text.

1. Disclosure Title:

A DC Capacitor voltage balancing SPWM algorithm utilized in 3 levels Vienna converters

2. Inventor:

Lin Ma, TinHo Li, KuenFaat Yuen &. Kai Tian.

3. Principal Applications/Uses of the Disclosure

Full DC Bus Voltage Components

Half DC Bus Voltage Components

AC

DC

VDC_UP

VDC_DW

Figure 1: Application Topology

• DC bus voltage balancing is a key issue for multi-level converters;

• Different PWM methods are utilized to balance the DC bus voltage, most of the PWM methods

are based on Space Vector Pulse Width Modulation (SVPWM) [1-3]. Usually, the related SVPWM

control the DC bus voltage by using different zero sequence vector;

• However, for the Vienna converter as shown in Fig.1, there are only 3 bi-directional switches

needed to be controlled. Using SVPWM will increase the software complexity;

• This ID proposed a DC balancing method based on SPWM through modifying the modulation

waveforms.

4. Problem Overcome by the Disclosure

Background and Existing Problems

1. To build a new 3 phases, 20~25 kW, 3-level Vienna rectifier with MOSFET and medium

switching frequency (30~40 kHz);

2. Generally, SVPWM is widely utilized in 3 phases 3 level system [1, 2], which could widen the

DC voltage range, improve the efficiency and realize DC bus balancing by modifying the zero

vector usage;

3. However, for Vienna converter, there are only three bi-directional switches. Using SVPWM will

increase the software complexity and it’s a kind of wasting the limited MCU resource;

4. Compared with SVPWM, SPWM is more simply and easy to be implemented;

5. And the DC voltage range could be widen with 3rd harmonic injection technique;

6. However, the SPWM DC bus balancing control is not easy to be implemented within 4 quarters

running condition [3];

7. BUT, in EV charger applications, the Vienna converter only has one power factor working point,

which makes the DC bus balancing control easy to be implemented;

8. For DC bus balancing control based on SPWM, the inventors found some papers [4] discussed

about. But the simulation results cannot satisfy the inventors. And some results of the papers

has obviously errors.

9. Then, the inventors has to figure out a new DC bus balancing control algorithm based on

SPWM and utilized in our designed Vienna converter. That’s the ID came from.

Solution with the Disclosure

1. By using the proposed SPWM method, the DC bus voltage could be balanced ideally;

2. It only cost less than 3 us MCU resource with 150 M DSP to realize the whole PWM generation

control algorithm (including anti-Park transformation, 3rd harmonic injection calculation, DC bus

balancing control and PWM generation);

Business Benefits

The possible benefits that could be obtained from this Disclosure are:

- Saving MCU resource, saving hardware cost

- Easy to be implemented;

- Robust performance.

Detailed Description of the Disclosure

This Disclosure proposed a SPWM method to balance the DC bus voltage of 3 level Vienna converter

as shown in Fig.1. Fig.2 sh...