This video explains the concept of Sine Pulse Width Modulation (SPWM) and demonstrates its application in creating a pure sine wave inverter. The creator first explains the theory behind SPWM, detailing how varying the duty cycle of a pulse-width modulated signal can reconstruct an analog waveform. They then showcase a practical implementation using an Arduino and a low-pass filter. The main focus shifts to the EGS002 pure sine wave inverter module, highlighting its features, including voltage, current, and temperature protection, and a feedback system. The video details the process of building an inverter using the EGS002 module and a companion PCB (EGP 1000W), encountering challenges with component selection and a lack of proper English documentation. Despite initial issues with under-voltage shutdowns and waveform quality, the system is eventually made to work, although with significant standby power consumption and inaccurate LCD readings, leading to a cautionary conclusion about relying on Chinese products without clear English manuals.
Building a Pure Sine Wave Inverter with SPWM and the EGS002 Module
0:00-0:15 Introduction to SPWM: The video begins by explaining that a previous circuit produced a modified square wave inverter and that many viewers requested a demonstration of SPWM for pure sine wave output.
0:07-0:15 Sine Wave Inverter Concept: The basic idea of stepping up a modified square wave to mains voltage is presented, but the resulting waveform is not sinusoidal.
0:15-0:39 SPWM Explained:
SPWM stands for Sine Pulse Width Modulation.
It involves varying the duty cycle of a pulse-width modulated (PWM) signal to mimic an analog waveform.
By changing the duty cycle, the average voltage of the pulses is altered.
A sine wave can be reconstructed by using different duty cycles for different voltage levels of the sine wave.
An Arduino's 16-bit timer is used to create a PWM signal.
The sine wave is divided into 100 segments, and corresponding duty cycle values are stored in a lookup table.
The timer then adjusts the duty cycle according to this table.
A carrier frequency of 10 kHz is observed.
0:47-0:51 Low-Pass Filtering: An inductor and capacitor (LC filter) are used to filter out the high carrier frequency of the SPWM signal, converting it into a purer sine wave.
0:50-0:59 Challenges of SPWM Implementation: Building a practical hardware implementation of SPWM can be complex.
1:00-1:10 Introduction to EGS002 Module: The EGS002 is presented as a cheap pure sine wave inverter module with voltage, current, and temperature protection, and a feedback system.
1:13-1:32 Video Goal: To understand SPWM, build an inverter using the EGS002, and assess its viability as a DIY alternative.
1:45-2:00 Sponsorship: The video is sponsored by JLCPCB for PCB manufacturing.
2:00-2:27 Deeper Dive into SPWM: Reinforces the explanation of SPWM, duty cycles, and how they relate to average voltage.
2:50-4:06 Arduino SPWM Example: Details the use of an Arduino timer, lookup table, and oscilloscope to demonstrate SPWM generation and the need for a low-pass filter.
4:06-4:25 Applying SPWM to H-Bridge: Explains how the SPWM signal is applied to an H-bridge for power output.
5:20-6:27 EGS002 Module Analysis:
The module uses an EGE-A800 IC for feedback (voltage, current, temperature) and SPWM signal generation.
It operates at a high carrier frequency of 23.5 kHz.
Includes an LM393 op-amp for current feedback and IR2113 drivers for MOSFETs.
6:30-6:55 PCB (EGP 1000W) Issues:
The accompanying PCB design uses very small SMD components despite ample space.
The only available manual was in Chinese and difficult to understand.
The translated English manual was poor.
7:51-8:43 Assembly and Initial Testing: The creator sourced components, assembled the PCB, and connected the module. The initial output showed a pure sine wave at 8.5V RMS, but an under-voltage shutdown occurred due to a lack of high-voltage feedback.
9:55-10:25 Troubleshooting and Feedback Connection: Following the Chinese datasheet, modifications were made to connect the feedback capacitor and inductor to the high-voltage side. Adjustments to a potentiometer were needed to achieve stable operation.
10:25-10:38 Waveform Quality: The high-voltage waveform appeared acceptable, but the output voltage was not the desired 230V.
10:46-10:54 High Standby Power Consumption: The circuit drew approximately 20 watts even when idle, which is considered very poor efficiency.
10:57-11:05 LCD Issues: The optional LCD displayed incorrect values.
11:05-11:21 Overall Assessment: The module and PCB function acceptably, but lack of proper English documentation makes tweaking difficult.
11:21-11:36 Conclusion: The video concludes with a lesson on SPWM inverters and a cautionary note about the unreliability of Chinese products without clear English manuals.