Inverter tube current sampling circuit

Abstract

The invention discloses an inverter tube current sampling circuit. The circuit comprises: a half-bridge circuit, an inverter and a current transformer. One input terminal of the inverter is connected with the half-bridge circuit and the other input terminal is connected with one end of a primary winding of the current transformer. The other end of the primary winding is connected with the half-bridge circuit. Two output terminals of the inverter are high voltage terminals. One end of a secondary winding of the current transformer is grounded and the other end of the secondary winding is connected with an anode of a rectifier diode and one end of a sampling resistor respectively. A cathode of the rectifier diode is connected with a current sampling terminal. The other end of the sampling resistor is grounded. In the invention, the primary winding of the current transformer is connected between the input terminal of the inverter and the half-bridge circuit. A skeleton of the current transformer does not need to be high-pressure-resistant. A signal of the current sampling terminal can reflect the current of the tube and stability of the tube current can be increased.

Description

[technical field] [0001] The invention relates to lamp tubes, in particular to an inverter lamp tube current sampling circuit. [Background technique] [0002] The current sampling circuit of the inverter lamp tube in the prior art, such as figure 1 , including a half-bridge circuit, an inverter T1, and a current transformer T2. The two input terminals 6 and 7 of the inverter T1 are connected to the half-bridge circuit. The output terminal 3 of the inverter T1 is the high-voltage terminal + HV1, and the inverter The output terminal 1 of the transformer T1 is connected to one end 4 of the primary winding of the current transformer T2, the other end 3 of the primary winding is the high voltage terminal +HV2, one end 1 of the secondary winding of the current transformer T2 is grounded, and the secondary winding The other end 2 is connected to the current sampling terminal Isense through the rectification diode D1, and the cathode of the rectification diode D1 is connected to th...

AI Technical Summary

Problems solved by technology

[0004] Since the current transformer T2 is connected to the high-voltage side to detect the lamp current, the frame of the current transformer T2 is required to have a high withstand voltage, and it needs to be made of a high-voltage frame material (such as LCP); in addition, the working voltage of the high-voltage end + HV2 is 1000Vrms Around, the working frequency is between 50-80KHz. At this time, capacitors C2 and C3 will have leakage current, and a voltage will be generated on the sampling resistor R2. The signal of the current sampling terminal Isense will include two signals: ①The lamp current passes through the current mutual inductance The current signal induced by the device T2; ②The leakage current signal through the capacitor C3; in this way, when the capacitor C2, C3, and the high voltage terminal +HV1 change, it will cause the signal change of the current sampling terminal Isense, and this signal cannot truly reflect the lamp. Current, can not meet the required lamp current requirements

Images