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Initiate/Close Timing Design on inverter

Initiate/Close Timing Design on inverter

The content is from internet, and is used to explain what happens when you start inverter.

The initiation and termination of timing sequences are crucial to the system’s operational process. Timing sequences define the process from startup to normal operation and subsequently to shutdown. It is assumed here that startup and shutdown conditions have been set in the specification (Spec). Additionally, depending on how the SPS (Supervisory Protective System) is connected (whether it draws power from the PV or the Bus), the corresponding startup timing sequence may vary. In this scenario, we assume that the SPS is connected to the PV.

Initiate Timing

“When the SPS connects to PV, the startup process is as follows:

Step 1: After the SPS is powered on, before starting up, it first performs DSP initialization and Eeprom reading. Subsequently, the software system establishes eight tasks, and finally, the entire system is started.

Step 2: After the system starts, it goes through condition judgments in the Super Task, successively passing through four operating modes: PowerOn Mode, Idle Mode, PreCheck Mode, and Normal Mode (divided into two types: CanSinglePVMode, which allows bypassing, and NoSinglePVMode, which does not allow bypassing), to reach a normal operating state. These four modes are explained as follows:

PowerOn Mode:

After the SPS is powered on and the operating system takes over the entire software system, it enters Wait Mode after a delay of 500ms.

Idle Mode:

Entered from PowerOn Mode, it counts down for 20 seconds. When entered from other modes, it counts down for 60 seconds. After the countdown, it checks if the start-up conditions are met (PV voltage reaches the start-up voltage, insulation impedance detection is complete, grid phase sequence and frequency detection are complete). If met, it enters sPreChkMode after a delay.

PreCheck Mode:

Begins with a soft start of the BUS, then checks GFCI devices, relays, starts inverting PWM, and waits for the end of PV connection mode determination. Based on the results of the PV connection mode detection, it determines which Boost control to enable. If it can switch to bypass, it enters sCanSinglePVMode; otherwise, it enters sNoSinglePVMode.


A stable operating mode where bypassing is possible. In this mode, the switch between the entire system and bypass is handled, with a difference in two routes of DUTY.


A stable operating mode where bypassing is not possible. In this mode, the Boost control of the front stage of the entire system is handled.”

Close Timing

Fault Mode:

In Normal Mode, if a fault occurs, the system enters Fault Mode. After the fault is cleared, it enters Idle Mode and then sequentially executes the startup sequence. If the PV voltage is less than the shutdown voltage, it enters Shutdown Mode and shuts down the SPS.

Shutdown Mode:

Upon entering this mode, the SPS is shut down, and the entire system is in a de-energized state.”

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