A current detection circuit
A technology of current detection circuit and comparison circuit, applied in the direction of measuring current/voltage, measuring device, measuring electrical variable, etc., can solve the problems of output voltage fluctuation, limited application range, difficulty in meeting output voltage accuracy and ripple requirements, etc. achieve low cost
Active Publication Date: 2020-08-18
MORNSUN GUANGZHOU SCI & TECH
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Problems solved by technology
However, this method will cause certain fluctuations in the output voltage because the output voltage sampling signal includes the voltage drop of the current sampling resistor. Occasions with high voltage accuracy and ripple requirements
[0005] To sum up, current sampling of the main power circuit on the high voltage side or output side is difficult to meet the performance and cost requirements, which limits its application range
Method used
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[0030] Figure 5 It is the circuit schematic diagram of the first embodiment of the current detection circuit of the present invention. The circuit also includes a control power supply, which is used to provide the input regulated power supply Vcc for the negative current conversion circuit, and provide the output voltage adjustment circuit and the inverting comparison circuit. Reference voltage Vref; the connection relationship of each circuit module is:
[0031] Output voltage adjustment circuit, including resistor R2, resistor R3, operational amplifier U1 and capacitor C1; one end of resistor R2 is used as the input end of the output voltage adjustment circuit to connect to the voltage output end to receive the input voltage Vo, and the other end of resistor R2 passes through resistor R3 Connect the reference ground, the series point of the resistor R2 and the resistor R3 is connected to the inverting input terminal of the operational amplifier U1, the non-inverting input t...
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The invention discloses a current detection circuit, comprising a main power circuit, a sampling resistor, an output voltage adjustment circuit, an inverted amplification circuit, a comparison circuit, a negative current transformation circuit and a drive circuit. The negative current transformation circuit collects and detects current information in the main power circuit to obtain a current sampling voltage. An output voltage of the main power circuit is collected through adoption of the output voltage adjustment circuit and then is output through utilization of a negative feedback circuit composed of an operational amplifier. Inverted amplification is carried out on the output voltage of the negative feedback circuit through utilization of the inverted amplification circuit. The inversely amplified negative feedback voltage is compared with a current sampling voltage through utilization of a comparer. The current sampling voltage is output by the negative current transformation circuit. The comparer outputs a control signal to control a main power tube of the main power circuit through utilization of the drive circuit. A voltage and current double-closed-loop control function isrealized, a current peak control effect can be realized, negative current detection cost also can be reduced, circuit performance is improved, and the current detection circuit has relatively high application value.
Description
technical field [0001] The invention relates to a current detection circuit, in particular to a negative current detection circuit. Background technique [0002] In practical applications of power converters, in order to realize overcurrent protection or current closed-loop control, it is necessary to detect the current on the main power circuit. [0003] The commonly used method is to detect the current flowing through the main power circuit when the main switch tube is turned on, and then convert the current into a voltage that is easy to measure through the processing of the corresponding circuit, so as to realize the overcurrent protection or current closed-loop control of the power circuit. [0004] For non-isolated step-down circuits, it is necessary to convert the rectified pulsating voltage of the mains to a low voltage, such as 375V to 36V or lower, and the main power tube needs to withstand high voltage stress. For the bootstrap driven buck circuit, one of the met...
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IPC IPC(8): G01R19/00
CPCG01R19/00
Inventor 吴辉李永昌李斌华
Owner MORNSUN GUANGZHOU SCI & TECH