Compensated droop method for paralleling of power supplies (C-droop method)
View Patent ↗A power supply has multiple power supply modules connected in parallel. Each power supply module has a power conversion circuit having an input coupled for receiving an input voltage. A resistor is serially coupled in an output of the power conversion circuit. A current limit amplifier has first and second inputs coupled to first and second terminals of the first resistor. A feedback amplifier has a first input coupled for receiving an output voltage of the power supply module, a second input coupled for receiving a reference signal, and an output coupled for providing a feedback signal to the power conversion circuit. A compensation resistor is coupled between an output of the current limit amplifier and the second input of the feedback amplifier for adjusting the reference signal to compensate for variation in output current of the power conversion circuit.
1. A power supply system, having multiple power modules connected in parallel, each power module comprising:
a power train, with an input connected to an input voltage, and output connected to the load through output droop resistance and current sensor;
a voltage feedback amplifier, with negative input connected to the output voltage, and positive input connected to the sum of a reference voltage and an output voltage of the current sensor; and
a control circuit, with one input connected to the output of current sensor, a second input connected to the output of the voltage feedback amplifier, and the output connected to the power train.
2. A power supply having a plurality of power supply modules connected in parallel, each power supply module comprising:
a power conversion circuit having an input coupled for receiving an input voltage and an output providing an output voltage of the power supply module;
a first resistor serially coupled in the output of the power conversion circuit;
a first amplifier having first and second inputs coupled to first and second terminals of the first resistor;
a second amplifier having a first input coupled for receiving the output voltage of the power supply module, a second input coupled for receiving a first reference signal, and an output coupled for providing a feedback signal to the power conversion circuit;
a second resistor coupled between an output of the first amplifier and the second input of the second amplifier for adjusting the first reference signal to compensate for variation in output current of the power supply module;
an I/O trim pin coupled for receiving a trim voltage; and
a third resistor coupled between the I/O trim pin and the second input of the second amplifier.
3. In a power supply module having a power conversion circuit for converting an input voltage to an output voltage, a compensation circuit comprising:
a feedback control loop having a first input coupled for receiving the output voltage of the power supply module, a second input coupled for receiving a reference signal, and an output coupled for providing a feedback signal to the power conversion circuit for controlling its output voltage;
a current sensor coupled in an output of the power conversion circuit and having an output coupled to the feedback control loop for adjusting the reference signal to compensate for variation in output current of the power supply module;
a first resistor serially coupled in the output of the power conversion circuit;
a first amplifier having first and second inputs coupled to first and second terminals of the first resistor;
a second resistor coupled between an output of the first amplifier and the second input of the feedback control loop;
an I/O trim pin coupled for receiving a trim voltage; and
a third resistor coupled between the I/O trim pin and the second input of the feedback control loop.
4. A method of compensating an output voltage of a power supply module, comprising:
monitoring an output current of the power supply module;
generating a compensation voltage representative the output current of the power supply module;
controlling an output voltage of the power supply module by comparing a signal representative of the output voltage of the power supply module to a reference signal;
utilizing the compensation voltage to adjust the reference signal and compensate for variation in output current of the power supply module; and
adjusting the reference signal with a trim voltage.
5. The method of claim 4 , further including providing load regulation of a plurality of power supply modules connected in parallel by adjusting a reference signal with a respective compensation voltage of each power supply module.
6. The method of claim 4 , further including connecting a plurality of the power supply modules in parallel.