Control circuit applied to lifting platform and method of controlling the same

A control circuit applied to a lifting platform configured to control a motor to adjust a height of a platform, the control circuit comprising:

• a conversion circuit, configured to receive an input voltage and provide an output voltage to control the motor, the conversion circuit comprising:
• an AC/DC conversion circuit, configured to convert the input voltage into a DC voltage, and
• a DC/DC conversion circuit, configured to convert the DC voltage into the output voltage,
• a detection unit, configured to detect an output end of the AC/DC conversion circuit and provide a detection signal, and
• a control unit, configured to provide a PWM signal according to the detection signal to control the DC/DC conversion circuit so that the DC/DC conversion circuit converts the DC voltage into the output voltage,
• wherein the control unit sets a power supply threshold;
• when the control unit realizes that the DC voltage or a DC power provided by the AC/DC conversion circuit is less than the power simply threshold according to the detection signal, the control unit decreases a duty cycle of the PWM signal to decrease a rotation speed of the motor, and maintains the DC voltage or the DC power is greater than or equal to the power supply threshold, and
• wherein the power supply threshold is a voltage threshold;
• the detection unit detects the DC voltage and provides the detection signal to the control unit;
• the control unit compares the detection signal with the voltage threshold and decreases the duty cycle when the DC voltage corresponding to the detection signal is less than or equal to the voltage threshold.

A method of controlling a lifting platform, comprising steps of:

• setting a power supply threshold, and controlling a DC/DC conversion circuit to convert a DC voltage provided by an AC/DC conversion circuit into an output voltage to control a motor,
• detecting an output end of the AC/DC conversion circuit to provide a detection signal, and adjusting a PWM signal of controlling the DC/DC conversion circuit according to the detection signal, and
• decreasing a duty cycle of the PWM signal to decrease a rotation speed of the motor when the DC voltage or a DC power provided by the AC/DC conversion circuit is less than the power supply threshold according to the detection signal, and maintaining the DC voltage or the DC power to be greater than or equal to the power supply threshold, and
• wherein the power supply threshold is a power threshold, and the AC/DC conversion circuit provides a DC current to the DC/DC conversion circuit, the control method further comprises steps of:
• detecting the DC voltage and the DC current to provide the detection signal,
• calculating the DC power according to the detection signal, and setting a maximum output power as the power supply threshold when tracking the DC power at the maximum output power, and
• decreasing the duty cycle when the DC power is less than or equal to the maximum output power.

A method of controlling a lifting platform, comprising steps of:

• setting a power supply threshold, and controlling a DC/DC conversion circuit to convert a DC voltage provided by an AC/DC conversion circuit into an output voltage to control a motor,
• detecting an output end of the AC/DC conversion circuit to provide a detection signal, and adjusting a PWM signal of controlling the DC/DC conversion circuit according to the detection signal, and
• decreasing a duty cycle of the PWM signal to decrease a rotation speed of the motor when the DC voltage or a DC power provided by the AC/DC conversion circuit is less than the power supply threshold according to the detection signal, and maintaining the DC voltage or the DC power to be greater than or equal to the power supply threshold, and
• wherein the power supply threshold is a voltage threshold, and the control method further comprises steps of:
• detecting the DC voltage to provide the detection signal, and
• realizing the DC voltage according to the detection signal, and comparing the DC voltage with the voltage threshold to decrease the duty cycle when the DC voltage is less than or equal to the voltage threshold,
• wherein a power load curve is formed by the DC voltage and a DC current provided by the AC/DC conversion circuit, and the DC voltage corresponding to a maximum output power of the power load curve is set to the voltage threshold.