Power supply with dual conversion circuits and discharge path for output capacitors
A power supply including a first conversion circuit, a second conversion circuit, a first output capacitor, a second output capacitor, a first discharge circuit, and a second discharge circuit is provided. The first conversion circuit converts a first alternating current (AC) power to a first direct current (DC) power. The second conversion circuit converts a second AC power to a second DC power. The first output capacitor is configured to store the first DC power. The second output capacitor is configured to store the second DC power. The first discharge circuit provides a first discharge path to discharge the first output capacitor in response to the first DC power being greater than the second DC power. The second discharge circuit provides a second discharge path to discharge the second output capacitor in response to the second DC power being greater than the first DC power.
1 . A power supply comprising: a first conversion circuit converting a first alternating current (AC) power to a first direct current (DC) power; a second conversion circuit converting a second AC power to a second DC power; a first output capacitor configured to store the first DC power; a second output capacitor configured to store the second DC power; a first discharge circuit creating a first discharge path to discharge the first output capacitor in response to the first DC power being greater than the second DC power; and a second discharge circuit creating a second discharge path to discharge the second output capacitor in response to the second DC power being greater than the first DC power, wherein: the first conversion circuit comprises: an AC-DC converter converting the first AC power to a first voltage; a boost circuit processing the first voltage to generate a second voltage; a buck circuit processing the second voltage to generate the first DC power; and a feedback compensation circuit generating a feedback signal according to the first DC power, wherein the buck circuit adjusts the first DC power according to the feedback signal; wherein the buck circuit comprises: a first pulse-width modulation (PWM) circuit generating a first switching signal and a second switching signal according to the feedback signal; a first switch receiving the first switching signal and coupled between a first node and a second node; a second switch receiving the second switching signal and coupled between the second node and the ground terminal; a resonant circuit coupled between the second node and the ground terminal to generate a resonant voltage; and a transformer generating the first DC power according to the resonant voltage.
2 . The power supply as claimed in claim 1 , wherein the first discharge circuit comprises:
a discharge switch coupled to the first output capacitor;
a resistance element coupled between the discharge switch and the ground terminal; and
a comparator circuit turning on the discharge switch in response to the first DC power being greater than the second DC power,
wherein in response to the discharge switch being turned on, the discharge switch and the resistance element form the first discharge path.
3 . The power supply as claimed in claim 1 , wherein the resonant circuit comprises:
a first inductor;
a second inductor; and
a resonant capacitor,
wherein the first inductor, the second inductor, and the resonant capacitor are connected in series with one another and between the second node and the ground terminal.
4 . The power supply as claimed in claim 3 , wherein the second inductor is connected to a primary winding of the transformer in parallel.
5 . The power supply as claimed in claim 4 , wherein the first discharge circuit comprises:
a discharge switch coupled between the first output capacitor and the second inductor; and
a comparator circuit turning on the discharge switch in response to the first DC power being greater than the second DC power,
wherein in response to the discharge switch being turned on, the discharge switch, the second inductor, and the resonant capacitor form the first discharge path.
6 . The power supply as claimed in claim 5 , wherein the feedback compensation circuit comprises:
a first voltage divider circuit processing the first DC power to generate a first divided voltage;
a compensation capacitor receiving the first divided voltage and coupled to the comparator circuit;
a voltage regulator coupled between the compensation capacitor and the ground terminal and receiving the first divided voltage;
a linear optical coupler generating the feedback signal according to the first DC power;
a turn-on resistor coupled between the first output capacitor and the linear optical coupler; and
a feedback capacitor coupled between the linear optical coupler and the ground terminal.
7 . The power supply as claimed in claim 6 , wherein the AC-DC converter comprises:
a bridge-type rectifier converting the first AC power to generate the first voltage; and
an input capacitor storing the first voltage.
8 . The power supply as claimed in claim 7 , further comprising:
a second voltage divider circuit processing the first voltage to generate a second divided voltage;
a second PWM circuit receiving the second divided voltage and providing a third switching signal;
a power switch receiving the third switching signal;
a boost inductor coupled between the second voltage divider circuit and the power switch;
an output diode coupled between the boost inductor and the first node; and
a boost capacitor coupled between the first node and the ground terminal.
9 . A control system comprising: a first power supply comprising: a first input terminal configured to receive a first AC power; a first conversion circuit converting the first AC power to a first DC power; a first output capacitor configured to store the first DC power; a first discharge circuit creating a first discharge path to discharge the first output capacitor in response to the first DC power being greater than a second DC power;
and a first output terminal configured to output the first DC power; a second power supply comprising: a second input terminal configured to receive a second AC power; a second conversion circuit converting the second AC power to the second DC power; a second output capacitor configured to store the second DC power; a second discharge circuit creating a second discharge path to discharge the second output capacitor in response to the second DC power being greater than the first DC power; and a second output terminal configured to output the second DC power; and a system load comprising: a first interface comprising: a first power-receiving terminal; and a first connection terminal, wherein in response to the first output terminal being coupled to the first interface, the first power-receiving terminal receives the first DC power and the first connection terminal is connected to the first discharge circuit; and a second interface comprising: a second power-receiving terminal electrically connected to the first power-receiving terminal; and a second connection terminal electrically connected to the first connection terminal, wherein in response to the second output terminal being coupled to the second interface, the second power-receiving terminal receives the second DC power and the second connection terminal is connected to the second discharge circuit, Wherein:
the first conversion circuit comprises: an AC-DC converter converting the first AC power to a first voltage; a boost circuit processing the first voltage to generate a second voltage; a buck circuit processing the second voltage to generate the first DC power; and a feedback compensation circuit generating a feedback signal according to the first DC power, wherein the buck circuit adjusts the first DC power according to the feedback signal, the buck circuit comprises: a first pulse-width modulation (PWM) circuit generating a first switching signal and a second switching signal according to the feedback signal; a first switch receiving the first switching signal and coupled between a first node and a second node; a second switch receiving the second switching signal and coupled between the second node and the ground terminal; a resonant circuit coupled between the second node and the ground terminal to generate a resonant voltage; and a transformer generating the first DC power according to the resonant voltage.
10 . The control system as claimed in claim 9 , wherein the first discharge circuit comprises:
a discharge switch coupled to the first output capacitor;
a resistance element coupled between the discharge switch and the ground terminal; and
a comparator circuit turning on the discharge switch in response to the first DC power being greater than the second DC power,
wherein in response to the discharge switch being turned on, the discharge switch and the resistance element form the first discharge path.
11 . The control system as claimed in claim 10 , wherein in response to the first output terminal being coupled to the first interface, an inverting input terminal of the comparator circuit is electrically connected to the first connection terminal.
12 . The control system as claimed in claim 9 , wherein the resonant circuit comprises:
a first inductor;
a second inductor; and
a resonant capacitor,
wherein the first inductor, the second inductor, and the resonant capacitor are connected in series between the second node and the ground terminal.
13 . The control system as claimed in claim 12 , wherein the second inductor is connected to a primary winding of the transformer in parallel.
14 . The control system as claimed in claim 13 , wherein the first discharge circuit comprises:
a discharge switch coupled between the first output capacitor and the second inductor; and
a comparator circuit turning on the discharge switch in response to the first DC power being greater than the second DC power,
wherein in response to the discharge switch being turned on, the discharge switch, the second inductor, and the resonant capacitor form the first discharge path.
15 . The control system as claimed in claim 14 , wherein in response to the first output terminal being coupled to the first interface, an inverting input terminal of the comparator circuit is electrically connected to the first connection terminal.
16 . The control system as claimed in claim 15 , wherein the first power supply comprises:
a voltage divider circuit processing the first DC power to generate a divided voltage;
a compensation capacitor coupled between the voltage divider circuit and a non-inverting input terminal of the comparator circuit;
a voltage regulator coupled between the compensation capacitor and the ground terminal and receiving the divided voltage;
a linear optical coupler generating the feedback signal according to the first DC power;
a feedback capacitor coupled between the linear optical coupler and the ground terminal; and
a detection resistor coupled between the inverting input terminal and the non-inverting input terminal.