CN204304467U - A kind of and from net inversion commutation circuit - Google Patents

Abstract

The utility model discloses an on-off-grid inverter switching circuit, which comprises a double-pole double-throw relay (RL1). The double-pole double-throw relay (RL1) is provided with two sets of synchronous contacts. The two terminals are respectively connected with the grid live terminal (GRID_L) and one of the moving terminals of the first single-pole double-throw relay (RL2), and the two terminals of the other set of contacts on the double-pole double-throw relay (RL1) are respectively connected with The grid neutral terminal (GRID_N) is connected to the first moving end of the second SPDT relay (RL3); the fixed ends of the first SPDT relay (RL2) and the second SPDT relay (RL3) are respectively connected to The two EPS output terminals (L_PLOCAL and N_PLOCAL) are connected; the second moving ends of the first SPDT relay (RL2) and the second SPDT relay (RL3) are respectively connected to the two H-bridge inverters of the inverter The subsequent stages (L_RELAY and N_RELAY) are connected.

Description

An off-grid inverter switching circuit

technical field

The utility model relates to a grid-connected and off-grid inverter switching circuit, in particular to a circuit for switching off-grid and grid-connected modes in a photovoltaic inverter circuit.

Background technique

In the field of photovoltaic power generation, in order to solve the instability and intermittency of photovoltaic power for the two-way power supply mode of grid-connected and off-grid, it is necessary to apply photovoltaic power in areas with electricity and complement it with mains power to provide users with satisfactory The continuous and uninterrupted power demand of the load requires the mutual switching between the off-grid photovoltaic power system and the mains power supply system. Under normal circumstances, if a photovoltaic inverter needs to have two working modes of grid-connected and off-grid, it needs to be able to switch between the grid-connected and off-grid states. Therefore, it is usually necessary to detect and detect the grid situation in real time.

Utility model content

The purpose of the utility model is to provide a grid-connected and off-grid inverter switching circuit. It can conveniently switch between on-grid and off-grid states, effectively enabling the inverter to switch in time when the user's load demand changes.

The technical scheme of the utility model: a parallel and off-grid inverter switching circuit, which is characterized in that it includes a double-pole double-throw relay, and the double-pole double-throw relay is provided with two sets of synchronous contacts. The two terminals are respectively connected with the live wire end of the power grid and one of the moving ends of the first SPDT relay, and the two terminals of the other group of contacts on the double pole double throw relay are respectively connected with the neutral wire terminal of the power grid and the second SPDT relay. The first moving end of the throwing relay is connected; the fixed ends of the first SPDT relay and the second SPDT relay are respectively connected to the two EPS output ends; the first SPDT relay and the second SPDT The second moving end of the relay is respectively connected with the two H-bridge inverter rear stages of the inverter.

In the above-mentioned grid-connected and off-grid inverter switching circuit, when the inverter is connected to the grid, the two sets of contacts of the double-pole double-throw relay are closed, and the switches of the first single-pole double-throw relay and the second single-pole double-throw relay are turned to The first moving end; when the utility power fails, the inverter quickly switches to EPS mode, the two sets of contacts of the double-pole double-throw relay are opened at the same time, and the switches of the first single-pole double-throw relay and the second single-pole double-throw relay are simultaneously Dial to the second moving end.

In the above-mentioned grid-connected and off-grid inverter switching circuit, three capacitors connected in parallel are connected between the two H-bridge inverter stages of the inverter, which are used for adjusting the parameter C of the capacitor among the LC parameters of the EPS off-grid.

Compared with the prior art, the utility model uses a combination of various simple relays to realize fast switching of the on-grid and off-grid states, and the utility model can share the same H-bridge inverter in the off-grid mode and the grid-connected mode circuit, reducing the system construction cost.

Description of drawings

Fig. 1 is a structural representation of the utility model.

Detailed ways

The utility model will be further described below in conjunction with the accompanying drawings and embodiments, but it is not used as a basis for limiting the utility model.

Example. An off-grid inverter switching circuit, as shown in Figure 1: it includes a double-pole double-throw relay RL1, and the double-pole double-throw relay RL1 is provided with two sets of synchronous contacts, and the two terminals of one set of contacts They are respectively connected to the grid live terminal GRID_L and one of the moving terminals of the first single-pole double-throw relay RL2, and the two terminals of the other set of contacts on the double-pole double-throw relay RL1 are respectively connected to the grid neutral terminal GRID_N and the second single-pole The first moving end of the double-throw relay RL3 is connected; the fixed ends of the first single-pole double-throw relay RL2 and the second single-pole double-throw relay RL3 are respectively connected to the two EPS output terminals L_PLOCAL and N_PLOCAL; the first single-pole double-throw The second moving ends of the relay RL2 and the second SPDT relay RL3 are respectively connected with the two H-bridge inverter rear stages L_RELAY and N_RELAY of the inverter. Three capacitors C1, C2 and C3 connected in parallel are connected between the two H-bridge post-inversion stages L_RELAY and N_RELAY of the inverter.

When the inverter is connected to the grid, the two sets of contacts of the double-pole double-throw relay RL1 are closed, and the switches of the first single-pole double-throw relay RL2 and the second single-pole double-throw relay RL3 are turned to the first moving end; After a fault occurs, the inverter quickly switches to the EPS mode, the two sets of contacts of the double-pole double-throw relay RL1 are opened at the same time, and the switches of the first single-pole double-throw relay RL2 and the second single-pole double-throw relay RL3 are simultaneously turned to the second. end.

Claims (2)

1. one kind and from net inversion commutation circuit, it is characterized in that: comprise dpdt relay (RL1), dpdt relay (RL1) is provided with two groups of synchronous contacts, wherein two terminals of one group of contact are connected with the first single-pole double-throw relay (RL2) one of them moved end with electrical network live wire end (GRID_L) respectively, and two terminals of described dpdt relay (RL1) another group contact upper are connected with the second single-pole double-throw relay (RL3) first moved end with electrical network zero line side (GRID_N) respectively; Described first single-pole double-throw relay (RL2) is connected with two EPS outputs (L_PLOCAL with N_PLOCAL) respectively with the not moved end of the second single-pole double-throw relay (RL3); Described first single-pole double-throw relay (RL2) is connected with two H bridge inversions rear class (L_RELAY with N_RELAY) of inverter respectively with the second moved end of the second single-pole double-throw relay (RL3).

2. according to claim 1 and from net inversion commutation circuit, it is characterized in that: between two H bridge inversions rear class (L_RELAY and N_RELAY) of described inverter, to be connected with three electric capacity (C1, C2 and C3) in parallel.