# A Design of PWM Controlled Calibrator of Non-Sinusoidal Voltage Waveforms

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## Abstract

**:**

## 1. Introduction

## 2. System Description

#### 2.1. Discrete Fourier Transform

_{1}is the fundamental voltage harmonic period and T

_{s}is the sample time, which specifies the algorithm execution rate. The magnitude and phase angle of the specified harmonics are then calculated from the complex output of the DFT block as seen in Figure 2.

#### 2.2. Voltage PI Controllers

_{p}and T

_{i}are PI controller proportional gain and integral time constants, respectively. Moreover, measures to prevent the PI controller windup effect are also implemented. The PI controller’s output magnitudes are limited to the values suitable for laboratory voltage reference generator while PI controllers phase angle outputs are limited from –π to π.

#### 2.3. Voltage Reference Generator

_{DC}is the DC link voltage.

## 3. Simulation Results

## 4. Laboratory Setup

#### 4.1. Anti-Aliasing Filter

#### 4.2. ControlDesk

## 5. Algorithm Optimization

_{s}. Sample time was set to 200 µs, thus according to reference (2), one period of fundamental voltage harmonic is described with 100 equally spaced samples.

_{2}) may be expressed as

_{1}and S

_{2}are calculated inside the triggered subsystem while M

_{1}and M

_{2}are obtained from the Master PPC.

## 6. Experimental Results

^{st}, 5

^{th}, and 7

^{th}harmonics as well as the first switching harmonics in the vicinity of 5 kHz, magnitudes of all other harmonics are below 0.1 % of the fundamental harmonic magnitude. The main reason why harmonics with magnitude less than 0.1 % of the fundamental harmonic magnitude are not considered is the 12-bit analog-to-digital (A/D) converter resolution of the DS1104 controller board. This is equivalent to the –60 dB and it is at least 10 dB greater than the noise floor. Higher accuracy and improved computational efficiency of presented calibrator can be achieved by replacing 12-bit with 24-bit A/D converters, using higher switching frequency and faster controllers based on the field programmable gate array (FPGA) technology, which is the objective of our future work. In this way, the calibrator will satisfy the requirements of Class A instruments [25].

## 7. Conclusions

## Author Contributions

## Funding

## Conflicts of Interest

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Harmonic Order | Parameter | Mean | Standard Deviation |
---|---|---|---|

1 | Magnitude Phase angle | 100 V 60 ° | 0.0084 V 0.0074 ° |

5 | Magnitude Phase angle | 8 V 30 ° | 0.0068 V 0.0643 ° |

7 | Magnitude Phase angle | 4 V –30 ° | 0.0081 V 0.1133 ° |

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**MDPI and ACS Style**

Petrovic, G.; Bosnic, J.A.; Majic, G.; Despalatovic, M. A Design of PWM Controlled Calibrator of Non-Sinusoidal Voltage Waveforms. *Energies* **2019**, *12*, 1966.
https://doi.org/10.3390/en12101966

**AMA Style**

Petrovic G, Bosnic JA, Majic G, Despalatovic M. A Design of PWM Controlled Calibrator of Non-Sinusoidal Voltage Waveforms. *Energies*. 2019; 12(10):1966.
https://doi.org/10.3390/en12101966

**Chicago/Turabian Style**

Petrovic, Goran, Juraj Alojzije Bosnic, Goran Majic, and Marin Despalatovic. 2019. "A Design of PWM Controlled Calibrator of Non-Sinusoidal Voltage Waveforms" *Energies* 12, no. 10: 1966.
https://doi.org/10.3390/en12101966