Power detection circuit for switching power supply

Abstract

The invention discloses a power detection circuit for a switching power supply, and the circuit is disposed on a power line. The power line is provided with at least one current sampling resistor. The circuit comprises a current detection circuit which is provided with a current sampling end and a current output end in parallel connection with the current sampling resistor and is used for detecting the value of a current in the power line; a voltage detection circuit which is provided with a voltage sampling end and a voltage output end, which are in connection with a positive electrode and a negative electrode, and is used for detecting the value of a voltage in the power line; and a multiplying circuit which is connected with the current output end and the voltage output end, enables the detected current and voltage to be multiplied, and outputs the power value. The current detection circuit comprises a first current-limiting resistor, a decoupling capacitor, an optical coupled isolator and a first differential amplification circuit, wherein the first current-limiting resistor, the decoupling capacitor, the optical coupled isolator and the first differential amplification circuit are connected sequentially. The voltage detection circuit comprises a second differential amplification circuit. The voltage measurement value and the current measurement value are multiplied through the multiplying circuit, thereby obtaining the power. The whole power detection circuit is precise in voltage detection, is small in operation current, and is low in cost.

Description

technical field [0001] The invention belongs to the field of power detection and relates to a power detection circuit for detecting current, voltage and power of the output of a switching power supply. Background technique [0002] At present, switching power supplies are widely used in the electrical industry, especially in the field of power electronics technology. When using a switching power supply, the power of the switching power supply is detected, and the output of current and voltage is constantly grasped to facilitate the diagnosis and maintenance of the equipment and avoid unnecessary emergencies. However, there are three problems in the switching power supply power detection circuit used today: 1. The power detection circuit is mainly realized by a power meter, and rarely detects current and voltage at the same time; 2. The current sensor used in the power detection circuit cannot detect small currents. Accurate detection; 2. Most power detection circuits use cu...

AI Technical Summary

Problems solved by technology

However, there are three problems in the switching power supply power detection circuit used today: 1. The power detection circuit is mainly realized by a power meter, and rarely detects current and voltage at the same time; 2. The current sensor used in the power detection circuit cannot detect the tiny current. Accurate detection; 2. Most power detection circuits use current or voltage sensors, which greatly increases the manufacturing cost

[0003] When using a power meter to measure the power of the switching power supply, since the power meter can only test the power of the whole product, limited by the current measurement range, it is impossible to measure the power of micro-power components

When a large system fails, it is impossible to find out the fault point and diagnose the fault only by analyzing the output power.

[0004] When the input of the circuit has unexpected interference or the output is connected to a sensitive load, when the signal passes through the operational amplifier, the interference signal will be superimposed, and the current sensor cannot isolate the input and output signals, which will increase the detection error

[0005] When detecting tiny signals, if only the operational amplifier is used, the signal will be covered by the interference signal in the operational amplifier, making the circuit unable to work normally

[0006] Therefore, the prior art lacks a power detection circuit capable of simultaneously detecting current and voltage with low production cost, or requires a device to accurately detect tiny currents

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