Power supply system and apparatus
View Patent ↗The present invention relates to a switched mode power supply with programmable digital control and to a power supply system comprising a plurality of switched mode power supplies. The input terminals and the output terminals of the switched mode power supply system are separated by an insulation barrier, and the switched mode power supply comprises a conversion stage having at least one switching element. The switching element of the conversion stage, as well as any switching elements of a possible pre-regulator, is digitally controlled by a programmable digital circuit. In one embodiment of the switched mode power supply, the programmable digital circuit is located on the primary side of the insulation barrier.
1. A switched power supply comprising:
input terminals for receiving electric power and output terminals for delivering an output signal having an output voltage and an output current;
wherein the input terminals are separated from the output terminals by an insulation barrier so that the input terminals are provided on a primary side of the insulation barrier and the output terminals are provided on a secondary side of the insulation barrier;
a converter stage coupled between the input terminals and the output terminals, the converter stage having at least one controllable first switching element for generating a converter state duty cycle so as to cause the converter stage to generate the output signal; and
a digital circuit for controlling the switching element in dependence of at least one signal, wherein the digital circuit is located on the primary side of the insulation barrier, and
the switched mode power supply further comprises an amplifier located on the secondary side and arranged to receive the output voltage on a first amplifier input and produce an amplifier output signal that is to be transferred across the insulation barrier to the digital circuit,
wherein the digital circuit is a programmable digital circuit comprising a processing means, a working memory, and an at least partly non-volatile memory for storing executable commands,
and that the amplifier is frequency dependant having a transfer function characteristic that amplifies higher frequency components relative to the lower frequency components.
2. The switched mode power supply of claim 1 , wherein the amplifier is arranged to receive an output reference voltage signal from an auxiliary processor on a second amplifier input and that the amplifier output signal is an analogue output error signal.
3. The switched mode power supply of claim 1 , wherein the output voltage is the sole input to the amplifier and wherein the output reference voltage signal is generated within the programmable digital circuit.
4. The switched mode power supply of claim 1 , wherein the amplifier is frequency dependent having a transfer function characteristic that attenuates lower frequency components and amplifies higher frequency components.
5. The switched mode power supply of claim 1 , wherein
the converter stage can operate in a mode for delivering a substantially constant output power; and
the converter stage can operate in a mode for delivering a substantially constant output current.
6. The switched mode power supply of claim 1 , wherein
the programmable digital circuit comprises means for receiving a signal representing the input current of the converter stage;
the programmable digital circuit is adapted to deriving the output current from the signal representing the input current of the converter stage; and
the programmable digital circuit is further adapted to using the derived value of the output current in the control of the first switching element.
7. The switched mode power supply of claim 1 , further comprising a converter stage output controller adapted to control the value of the converter stage duty cycle; the converter stage output controller being at least party embodied by the programmable digital circuit.
8. The switched mode power supply of claim 5 , wherein the programmable digital circuit is further adapted to operate the converter stage so as to deliver a substantially constant output current in dependence on the derived value of the output current and information indicative of the converter stage duty cycle.
9. The switched mode power supply of claim 8 , wherein the programmable digital circuit is further adapted to enable the operation of the converter stage so as to deliver a substantially constant output current in dependence on the derived output current value and the information is indicative of the converter stage duty cycle when the value of the duty cycle is higher than a predetermined threshold value.
10. The switched mode power supply of claim 8 , wherein predetermined threshold value is a value of 0.4 or less.
11. The switched mode power supply of claim 1 , wherein the converter stage is a DCIDC converter stage.
12. The switched mode power supply of claim 1 , wherein the converter stage comprises four switching elements arranged in a full bridge, the programmable digital circuit being adapted to controlling the four switching elements.
13. The switched mode power supply of claim 12 , wherein
the programmable digital circuit is adapted to generating and sending one pulse width modulated signal to each of the four switching elements; and
the programmable digital circuit is further adapted to determining a phase shift in two, of the four pulse width modulated signals with respect to the other two of the four pulse width modulated signals, the phase shift being determined based on a desired value of the duty cycle of the full bridge.
14. The switched mode power supply of claim 1 , wherein the programmable digital circuit is adapted to use the mains frequency in determining timing of re-start attempts of the switched mode power supply.
15. The switched mode power supply of claim 1 , wherein
the programmable digital circuit is adapted to receiving a signal indicative of the mains voltage to which the input terminals of the switched mode power supply are connected; and
the programmable digital circuit is further adapted to using the signal in determining the maximum power delivered by the switched mode power supply.
16. The switched mode power supply of claim 1 , wherein the converter stage output controller is adapted to control the value of the converter stage duty cycle so that the converter stage operates in a mode for delivering a substantially constant output voltage.
17. The switched mode power supply of claim 1 , wherein at least one optocoupler is used for transmitting at least one signal across the insulating barrier.
18. The switched mode power supply of claim 1 , wherein the switched mode power supply comprises:
means for measuring a quantity;
means for generating a reference value of the quantity;
means for generating the difference between the measured value and the reference value of the quantity; and
the programmable digital circuit comprises means for converting the difference between the measured value and the reference value of the quantity into digital representation.
19. The switched mode power supply of claim 18 , wherein
the quantity is the output voltage of the switched mode power supply; and
the programmable digital circuit is further adapted to using the difference in the control of the first switching element.
20. A power supply system comprising:
a first switched mode power supply of claim 1 , the first switched mode power supply being adapted to deliver a first power output; and
a second switched mode power supply of claim 1 ; the second switched mode power supply being adapted to deliver a second power output;
and a distribution unit comprising:
a distribution unit input being connected to receive the fist power output and the second power output; and
at least one distribution unit output for supplying electric power to a load.
21. The switched mode power supply of claim 20 , wherein
the programmable digital circuit is adapted to receiving a signal indicative of the mains voltage to which the input terminals of the switched mode power supply are connected; and
the programmable digital circuit is further adapted to using the signal in determining the maximum power delivered by the switched mode power supply.
22. The switched mode power supply of claim 1 , wherein the programmable digital circuit is further arranged to apply a reverse transfer function on the amplifier output signal to retrieve a digital representation of the output voltage.