Patent US8441231

Bidirectional hysteretic power converter
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US8441231

1. A switching bidirectional power converter to efficiently convert power comprising: (6) (7)

an inductor coupled between a first main terminal of said power converter and a switching node;

a first power device coupled between said switching node and the negative terminal of said power converter;

a second power device coupled between said switching node and a second main terminal of said power converter; wherein the flow of power flows in a first direction from said first main terminal of said power converter to said second main terminal of said power converter when said power converter operates as a step up converter, and flows in a second direction from said second main terminal of said power converter to said first main terminal of said power converter when it operates as a step down converter;

a first feedback network to generate a first synthetic ripple signal when said power converter operates as a step up converter;

a second feedback network to generate a second synthetic ripple signal when said power converter operates as a step down converter;

a comparator providing hysteretic control of said power converter in response to said first and second synthetic ripple signals, to a reference signal, and to a mode selection signal; wherein said mode selection signal determines whether said power converter operates as a step up converter or as a step down converter, and

a control logic circuit and a pre-driver circuit for generating the signals to drive said first and second power devices in response to the output signal of said comparator.

2. The switching bidirectional power converter of claim 1, wherein said comparator is replaced by a first comparator to receive said first synthetic ripple signal from said first feedback network and by a second comparator to receive said second synthetic ripple signal from said second feedback network, and (0) (1)

3. The switching bidirectional power converter of claim 1, wherein said first and second feedback networks are replaced by one single feedback network to generate a synthetic ripple signal, in response to said mode selection signal, and (0) (1)

4. The switching bidirectional power converter of claim 1, wherein the switching frequency of said power converter is maintained substantially constant in continuous conduction mode by controlling the hysteresis levels of said comparator by means of a frequency control circuit. (0)

5. The switching bidirectional power converter of claim 1, wherein the switching frequency of said power converter is maintained substantially constant in continuous conduction mode by controlling the time constants of said first and second synthetic ripple signals of said first and second feedback networks by means of a frequency control circuit. (0)

6. The switching bidirectional power converter of claim 1, wherein the switching frequency in continuous conduction mode is substantially constant and (0) (1)

7. The switching bidirectional power converter of claim 1, wherein said first and said second feedback networks are comprising components to alter the operation of said switching bidirectional power converter depending on the conduction modes of said switching bidirectional power converter. (0)

8. A method to efficiently convert power from a first power source, coupled to a first main terminal of a power converter, to a second main terminal of said power converter or from a second power source, coupled to said second main terminal of said power converter, to said first main terminal of said power converter comprising: (6) (5)

switching a first power device and a second power device;

charging and discharging with a modulated duty cycle an inductor; whereby the flow of power in said inductor can be in a first direction or in a second direction in response to a mode selection signal;

generating a first synthetic ripple signal when the flow of power is in said first direction and a second synthetic ripple signal when the flow of power is in said second direction opposite to said first direction;

comparing said first or said second synthetic ripple signal to a reference signal by means of a comparator in response to said mode selection signal;

modulating the duty cycle of said first and second power devices in response to the output of said comparator, whereby the voltage appearing at said first main terminal when the flow of power is in said first direction or the voltage appearing at said second main terminal when the flow of power is in said second direction is regulated to be at a desired value, and

whereby the modulation of the duty cycle occurs by means of an hysteretic control.

9. The method of claim 8, wherein the voltage appearing at said second main terminal is regulated to be higher than the voltage of said first power source if the flow of power is in said first direction, and (0) (1)

10. The method of claim 8, wherein said comparator is replaced by a first comparator to receive said first synthetic ripple signal generated in a first feedback network, and by a second comparator to receive said second synthetic ripple signal generated in a second feedback network, and (0) (1)

11. The method of claim 8, wherein said first and second synthetic ripple signals are replaced by a single synthetic ripple signal generated by a feedback network in response to said mode selection signal and, (0) (1)

12. The method of claim 8, wherein the switching frequency is maintained substantially constant in continuous conduction mode by controlling the hysteresis levels of said comparator by means of a frequency control circuit. (0)

13. The method of claim 8, wherein the switching frequency is maintained substantially constant in continuous conduction mode by controlling the time constants of said first and second synthetic ripple signals by means of a frequency control circuit. (0)

14. The method of claim 8, wherein the switching frequency in continuous conduction mode is substantially constant and (0) (1)

15. A switching power converter to efficiently convert power from a power source to charge a battery comprising: (5) (8)

an inductor coupled between a first main terminal of said power converter and a switching node;

a first power device coupled between said switching node and the negative terminal of said power converter;

a second power device coupled between said switching node and a second main terminal of said power converter; wherein said battery is coupled to said first main terminal when said power source is coupled to said second main terminal, and

wherein said battery is coupled to said second main terminal when said power source is coupled to said first main terminal;

a first feedback network to generate a first synthetic ripple signal when said power converter operates in constant voltage mode;

a second feedback network to generate a second synthetic ripple signal when said power converter operates in constant current mode;

a first comparator providing hysteretic control of said switching power converter in response to said first synthetic ripple signal and to a first reference signal;

a second comparator providing hysteretic control of said switching power converter in response to said second synthetic ripple signal and to a second reference signal;

a control logic circuit and a pre-driver circuit for generating the signals to drive said first and second power devices in response to the output signals of said first and second comparator, and whereby the modulation of the duty cycle of said switching power converter occurs by means of an hysteretic control in constant current mode of operation and in constant voltage mode of operation.

16. The switching power converter of claim 15, wherein the flow of power flows in a first direction to charge said battery and in a second direction to convert power from said battery to a load when said power source is replaced by said load, and (0) (1)

17. The switching power converter of claim 15, wherein said second reference signal is replaced by the output signal of a transconductance amplifier that operates in response to a current reference signal and to an inductor current sensing signal. (0)

18. The switching power converter of claim 15, wherein the switching frequency is maintained substantially constant in continuous conduction mode by controlling the hysteresis levels of said first and second comparator by means of a frequency control circuit. (0)

19. The switching power converter of claim 15, wherein the switching frequency is maintained substantially constant in continuous conduction mode by means of a frequency control circuit, and (0) (1)

20. The switching power converter of claim 15, wherein said first and said second feedback networks are replaced by a single feedback network to generate a single synthetic ripple signal, and (0) (1)

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Patent US8441231

Bidirectional hysteretic power converter

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