1000W positive sine wave inverter production detailed explanation (illustration)

This is a 1000W sine wave inverter with an impressive efficiency of up to 94%, along with excellent protection features. It is designed to handle a variety of electrical loads, ensuring both reliability and performance.

Figure 1:

Figure 2:

Image 3:

Figure 4:

Figure 5:

Figure 6:

Figure 7:

Figure 8:

Figure 9:

Figure 10:

Figures 9 and 10 illustrate the inverter under a 1200W load, monitored using a WT230 power meter to track voltage, current, and power. An oscilloscope was used to monitor the inverter's output waveform. The inverter demonstrates a robust load-carrying capacity, capable of starting 1/2 HP motors, chainsaws, refrigerators, TVs, induction cookers, and microwaves. It includes various monitoring displays such as battery high voltage alarms, high voltage protection, battery low voltage alarms, low voltage protection, overtemperature alarms, overtemperature protection, output overvoltage protection, overload protection, short circuit protection, and remote control functionality.

Figure 11:

Figure 11 provides a detailed view of the PCB layout for a 1000W sine wave inverter.

Figure 12:

The schematic in Figure 11 comprises an auxiliary power supply, a DC-DC boost control section, and monitoring of DC input voltage, current, and power via a microprocessor.

Figure 13:

The schematic in Figure 13 consists of a DC-DC power section, a DC-AC power section, a DC-AC control section, and an output protection circuit. The DC-AC control primarily generates a pure sine wave through Microchip’s 16-bit DSP DSPIC30F2010 SPWM in the DC-AC power section. For more details on the SPWM generation algorithm, refer to the DSP programming section.

Figure 14:

Figure 15:

Figures 14 and 15 showcase the DSP DSPIC30F2010 program design. The algorithm for generating SPWM is briefly outlined below. A constant list is first created based on the alternating current expression Umsinωt, where Um represents the amplitude of the alternating current and also the DC boost. The software derives the SPWM with a varying duty cycle from the sinusoidal function by referencing the table, converting it into a pure sine wave voltage through the DC-AC power section. When Um remains constant, the output is a stable AC voltage; however, the actual DC boost is not entirely stable. Hence, it becomes necessary to multiply the AC expression Umsinωt by a coefficient C for compensation, resulting in a pure and stable sinusoidal AC voltage. The compensated AC expression is UmCsinωt, where C=Um/U. Um is the output sinusoidal AC voltage amplitude, and U is the current DC boost. The output achieves a stable sinusoidal AC voltage when U≥Um.

Here’s an example of compensation:

Assume the current DC boost U is 360V, the output voltage is 220V AC, and the AC power amplitude Um is 311.08V. Thus, C=311.08/360=0.864. At this point, the software looks up the constant in Umsinωt and multiplies it by 0.864 to obtain the current SPWM duty cycle.