Temperature sampling circuit and temperature detection method

A power conversion system, comprising a temperature sampling circuit, wherein the temperature sampling circuit comprises:

• a thermistor having a first terminal and a second terminal, wherein the first terminal is configured to be connected to a power supply voltage, and the second terminal is configured to be grounded;
• an adjustable reference resistor module connected to at least one of the first terminal and the second terminal, wherein the adjustable reference resistor module has a plurality of stages of different reference resistance values, and the reference resistance values of different stages correspond to different preset sampling voltage ranges;
• a sampling circuit having a sampling terminal and a sampling circuit output terminal, wherein the sampling terminal is connected to at least one of the first terminal and the second terminal to obtain a sampling voltage value;
• and
• a control circuit having a control circuit input terminal and a control circuit output terminal, wherein the control circuit input terminal is connected to the sampling circuit output terminal to receive the sampling voltage value, and the control circuit output terminal is connected to the adjustable reference resistor module;
• the control circuit is configured to determine a resistance value of the thermistor based on the sampling voltage value in response to the sampling voltage value falling within a preset sampling voltage range corresponding to a reference resistance value of the current stage, and the control circuit is further configured to switch to another stage with a different reference resistance value in response to the sampling voltage value not falling within a preset sampling voltage range corresponding to a reference resistance value of the current stage, so that a newly obtained sampling voltage value falls within a preset sampling voltage range corresponding to the reference resistance value of the stage after switching.

A temperature detection method, applied in temperature detection of a power conversion system by a temperature sampling circuit, the temperature sampling circuit comprises a thermistor, an adjustable reference resistor module, a sampling circuit, and a control circuit, the adjustable reference resistor module has a plurality of stages of different reference resistance values, and the reference resistance values of different stages correspond to different preset sampling voltage ranges,

• wherein the temperature detection method comprises:
• selecting a stage with a reference resistance value;
• obtaining, by the sampling circuit, a sampling voltage value at a sampling point under the current stage;
• transmitting the sampling voltage value to the control circuit;
• determining, by the control circuit, the sampling voltage value:
• when the sampling voltage value falls within a preset sampling voltage range corresponding to the reference resistance value of the current stage, determining a resistance value of the thermistor based on the sampling voltage value, and obtaining a current ambient temperature value based on the resistance value of the thermistor, or
• when the sampling voltage value does not fall within the preset sampling voltage range corresponding to the reference resistance value of the current stage, switching to another stage with a different reference resistance value, obtaining a new sampling voltage value at the sampling point under the stage after switching, and continue determining the new sampling voltage value.