CN105652062A

CN105652062A - Current detection circuit of full bridge converter power loop

Info

Publication number: CN105652062A
Application number: CN201410677577.6A
Authority: CN
Inventors: 谢君甫; 周振军; 张强
Original assignee: Leihua Electronic Technology Research Institute Aviation Industry Corp of China
Current assignee: Leihua Electronic Technology Research Institute Aviation Industry Corp of China
Priority date: 2014-11-21
Filing date: 2014-11-21
Publication date: 2016-06-08

Abstract

The invention, which belongs to the technical field of current detection, designs a current detection circuit of a full bridge converter power loop. The detection circuit consists of power MOSFET tubes, a transformer T1, transformers, a power supply and resistors. The MOSFET tubes S1 and S2 form a full-bridge left arm and the MOSFET tubes S3 and S4 form a full-bridge right arm. The transformer T1 is arranged between middle points of the full-bridge left arm and the full-bridge right arm in a bridging mode; one end of a primary side of each current transformer is connected to one of lower ends of the MOSFET tubes S2 and S4 and the other ends of the primary sides are connected together and are connected to a power supply ground terminal; and secondary sides of the transformers T2 and T3 are in an integrated half-wave rectification mode. The resistors R1 and R3 are connected in parallel to the secondary sides of the transformers T2 and T3; one end of each of the resistors R2 and R4 is connected in parallel to a half-wave rectification output terminal; and another end of each of the resistors R2 and R4 is connected with a CS and the other ends are of the resistors R2 and R4 grounded.

Description

The current detecting circuit of a kind of full-bridge converter loop of power circuit

Technical field

The invention belongs to current detection technology field, design the current detecting circuit of a kind of full-bridge converter loop of power circuit.

Background technology

The electric current detecting method in full bridge power loop conventional at present is as shown in Figure 1.

In upper figure, current sense transformer T2 is connected in main loop of power circuit. Under normal circumstances, this electrorheological depressor can normal operation. But in extreme circumstances, it may occur that the problems such as T2 magnetic bias, make T2 lose current sense function, and cause transformer T1 magnetic bias saturated further, damage full-bridge switch, cause the problems such as mapping fault.

Extreme situation is: full-bridge converter load is large capacitive load; Transformer secondary adopts synchronous rectification. When a big load changing occurs, due to the unexpected reduction of load current, causing output capacitance charging voltage higher than the regulating voltage of setting, at this moment regulation loop starts response to a minimum dutycycle. Meanwhile, the energy in output capacitance is discharged to primary return by synchronous rectifier, transformer T1, causes having reversible circulation to flow through at primary return. Owing to the balance of flux of current sense transformer T2 is destroyed, can not reset, cause magneticsaturation, lose current sense function. Control loop is when false current samples information, and the volt-second balance that can not maintain transformer T1 in the positive-negative half-cycle replaced causes T1 magneticsaturation, it is possible to damages loop of power circuit, causes mapping fault.

Summary of the invention

The technical problem that the present invention solves is: by changing the current detecting mode of current sense transformer, avoid the magneticsaturation that detection circuit itself occurs, reach complex condition still can accurate detection power loop current, correct control loop of power circuit work object.

The technical scheme of the present invention is: described detection circuit comprises power MOSFET tube, transformer T1, transformer, power supply and resistance, MOSFET pipe S1 and S2 forms the left arm of full bridge, MOSFET pipe S3 and S4 forms full bridge right arm, transformer T1 is connected across between the point midway of the left arm of full bridge and full bridge right arm, electric current primary one end is connected in the lower end of MOSFET pipe S2 and S4, the elementary the other end links together, and hold with being connected to power supply, the form of the secondary integrated half-wave rectification of transformer T2 and T3, resistance R1 and R3 is connected in parallel on the secondary of transformer T2 and T3, one end of resistance R2 and R4 is connected in parallel on the output terminal of half-wave rectification respectively, another termination CS place of resistance R2 and R4, the other end ground connection.

The technique effect of the present invention is: owing to each detection electrorheological depressor only flows through electric current in half switch periods, and only flow through forward current, magnetic extends reset time simultaneously, it is ensured that current sense transformer T2, T3 under various conditions can normal operation. Meanwhile, when left and right bridge arm occurs abnormal, when having the direct bridge arm from the left or right of electric current to circulate, also can be detected by transformer T2 and T3. This invention solves under specified conditions, the problem such as the full-bridge switch damage that causes due to magneticsaturation, mapping fault, it is to increase the reliability of circuit. This detection method can be applied in the Control protection circuit of full-bridge converter loop of power circuit.

Accompanying drawing explanation

Fig. 1 is prior art circuits schematic diagram;

Fig. 2 is circuit diagram of the present invention.

Embodiment

Four power switch S 1-S4 form full-bridge converter circuit. S1 is the upper pipe of the left arm of full bridge, and S2 is the lower pipe of the left arm of full bridge. S3 is the upper pipe of full bridge right arm, and S4 is the lower pipe of full bridge right arm. Power transformer T1 is connected across the point midway of full bridge left and right arms. Elementary one end of electrorheological depressor T2, T3 is connected in the lower end of S2 and S4 respectively, and the elementary the other end of T2, T3 links together, and holds with being connected to power supply. The form of the secondary integrated half-wave rectification of transformer T2 and T3, R1 and R3 is connected in parallel on the secondary of T2 and T3, plays the effect that magnetic resets. R2 and R4 is connected in parallel on the output terminal of half-wave rectification respectively, and meanwhile, R2 and R4 mono-termination CS, the other end is to ground. By the magnitude of voltage of CS, it is possible to the electric current that T1 flows through detected.

When transformer T1 secondary adopts synchronous rectification, and when the load of transformer T1 is large capacitive load. If a big load is dashed forward falls generation, due to the unexpected reduction of load current, causing exporting the regulating voltage of capacitive load charging voltage higher than setting, at this moment the voltage-regulation loop of circuit starts response to a minimum dutycycle. Meanwhile, the energy exported in capacitive load is discharged to primary return by synchronous rectifier, transformer T1, causes having reversible circulation to flow through at primary return.

Do not have due to electrorheological depressor T2 and T3 and T1 series connection, but connect with left and right bridge arm respectively, then it can only flow through electric current in half switch periods, and only flows through forward current, simultaneously magnetic extends reset time, it is ensured that current sense transformer T2, T3 when large capacitive load can normal operation.

When load is other kind load, T2 and T3 also can complete the detection of bridge arm current.

Meanwhile, when left and right bridge arm occurs abnormal, when having the direct bridge arm from the left or right of electric current to circulate, also can be detected by transformer T2 and T3.

So, this circuit can correctly detect out primary electric current and bridge arm fault current, completes the object of current detecting.

Claims

1. the current detecting circuit of a full-bridge converter loop of power circuit, it is characterized by: described detection circuit comprises power MOSFET tube, transformer T1, transformer, power supply and resistance, MOSFET pipe S1 and S2 forms the left arm of full bridge, MOSFET pipe S3 and S4 forms full bridge right arm, transformer T1 is connected across between the point midway of the left arm of full bridge and full bridge right arm, electric current primary one end is connected in the lower end of MOSFET pipe S2 and S4, the elementary the other end links together, and hold with being connected to power supply, the form of the secondary integrated half-wave rectification of transformer T2 and T3, resistance R1 and R3 is connected in parallel on the secondary of transformer T2 and T3, one end of resistance R2 and R4 is connected in parallel on the output terminal of half-wave rectification respectively, another termination CS place of resistance R2 and R4, the other end ground connection.