TWI853338B - Charging circuitry, charging method and power system for supercapacitor - Google Patents

Abstract

A charging circuitry for charging or discharging a supercapacitor includes a power electronic converter, a current sensor, a voltage boost/buck controller and a charging mode controller. The power electronic converter is configured to charge or discharge the supercapacitor according to a control command. The current sensor is coupled to the supercapacitor for detecting a first sensed voltage and a second sensed voltage. The voltage boost/buck controller is configured to generate the control command and a current command according to the first sensed voltage, the second sensed voltage and an overall feedback. The charging mode controller is configured to generate a current feedback and a voltage feedback to the voltage boost/buck controller according to a driving voltage, the current command and a third sensed voltage of the supercapacitor. The third sensed voltage, the current feedback and the voltage feedback are superposed and then inputted to the same input terminal of the voltage boost/buck converter as the overall feedback.

Description

Charging circuit, charging method and power system for supercapacitor

The present disclosure relates to a charging circuit, a charging method and a power system, and in particular to a charging circuit, a charging method and a power system for a supercapacitor.

Currently, the main charging methods for supercapacitors include constant current charging, constant voltage charging, constant current to constant voltage charging, pulse current charging, and constant power charging. Constant current charging has high efficiency, but in the later stages of charging, the voltage at both ends of the capacitor will be too large, affecting the energy storage capacity of the supercapacitor; constant voltage charging has low efficiency and a slow charging time; and constant power charging control circuits are more complex. In addition, it is known that the constant voltage charging mode uses a digital-to-analog converter (DAC) to control the chip to output a dynamic voltage command and make the voltage rise and fall controller follow the voltage command, but this function requires additional circuit costs. On the other hand, since completely discharging a battery will seriously affect its service life, ordinary batteries will not be charged from zero voltage. However, supercapacitors have no such limitation and their charging cycles are all charged from zero voltage to the rated voltage.

One aspect of the present disclosure is a charging circuit for charging or discharging a supercapacitor, and includes a power electronic converter, a current flow sensor, a voltage step-up and step-down controller, and a charging mode controller. The power electronic converter is used to charge or discharge the supercapacitor according to a control command. The current flow sensor is coupled to the supercapacitor and is used to sense a first sensing voltage and a second sensing voltage. The voltage step-up and step-down controller is coupled to the supercapacitor, the power electronic converter, and the current flow sensor, and is used to generate the control command and a current command according to the first sensing voltage, the second sensing voltage, and a total feedback. The charging mode controller is coupled to the supercapacitor and the voltage step-up controller, and is used to generate a current feedback and a voltage feedback to the voltage step-up controller according to a driving voltage, the current command and a third sensing voltage of the supercapacitor. The third sensing voltage, the current feedback and the voltage feedback are summed up and input to the same input terminal of the voltage step-up controller as the total feedback.

Another aspect of the present disclosure is a power system, comprising the aforementioned charging circuit, a supercapacitor and a power supply. The power supply is coupled to the charging circuit and is used to provide a charging power source and a driving voltage to the charging circuit during charging, so that the charging circuit charges the supercapacitor according to the charging power source and the driving voltage; and to store the power from the supercapacitor during discharging.

Another aspect of the present disclosure is a charging method for the aforementioned charging circuit, and includes: generating a current command according to a first sensing voltage, a second sensing voltage and a total feedback; providing a driving voltage, the current command and a third sensing voltage to a charging mode controller; converting the driving voltage into a first preset potential, a second preset potential, and converting the third sensing voltage into a fourth sensing voltage; and when the fourth sensing voltage is less than the second preset potential, When the fourth sensed voltage is greater than or equal to the second preset potential, a first constant power charging mode is performed on a super capacitor; when the fourth sensed voltage is greater than or equal to the second preset potential, a second constant power charging mode is performed on the super capacitor; and when the current command is less than the first preset potential, a constant voltage charging mode is performed on the super capacitor; wherein the third sensed voltage, the current feedback and the voltage feedback are summed up and input to the same input terminal of a voltage step-up and step-down controller to serve as the total feedback.

The following is a detailed discussion of embodiments of the present disclosure. However, it will be appreciated that the embodiments provide many applicable concepts that can be implemented in a variety of specific contexts.

FIG1 is a block diagram of a power system 10 according to an embodiment of the present disclosure. As shown in FIG1 , the power system 10 includes a power supply 11, a supercapacitor 12, and a charging circuit 10A. The charging circuit 10A is used to charge the supercapacitor 12, and includes a power electronic converter 13, a current sensor 14, a voltage step-up and step-down controller 15, and a charging mode controller 16. The charging mode controller 16 includes a constant current controller 16A and a constant voltage controller 16B.

The power supply 11 is used to provide charging power, driving voltage CV, and also to store power from the supercapacitor 12. The power supply 11 can be a DC power supply. The supercapacitor 12 can be an electrical double-layer capacitor (EDLC) or other suitable high-capacity electrochemical capacitors.

The power electronic converter 13 is coupled to the power supply 11, the current sensor 14 and the voltage step-up/down controller 15, and is used to convert the input power into the output power according to the control command CTRL of the voltage step-up/down controller 15. When the supercapacitor 12 is charged, the power electronic converter 13 converts the input power provided by the power supply 11 into the output power for the supercapacitor 12; when the supercapacitor 12 is discharged, the power electronic converter 13 converts the input power provided by the supercapacitor 12 into the output power for the power supply 11. The power electronic converter 13 can be a bi-directional DC-to-DC converter, a bi-directional buck-boost converter or other suitable bi-directional power electronic converters.

The current flow sensor 14 is coupled to the super capacitor 12, the power electronic converter 13 and the voltage step-up/down controller 15, and is used to sense the first sensing voltage ISENSE+ and the second sensing voltage ISENSE-. The current flow sensor 14 can be equivalent to a resistor RS, wherein the first end of the resistor RS is coupled to the power electronic converter 13 to sense the first sensing voltage ISENSE+, and the second end of the resistor RS is coupled to the super capacitor 12 to sense the second sensing voltage ISENSE-. It is worth noting that the current flow sensor 14 is arranged after the energy storage element (such as an inductor, not shown in FIG. 1 ) or the output end of the power electronic converter 13 to avoid sensing the noise from the input end of the power supply 11. The current flow sensor 14 may be a direct current resistor (DRC), a shunt resistor, a surface mount device (SMD) chip resistor or other suitable current flow sensing components or circuits.

The voltage step-up/down controller 15 is coupled to the power supply 11, the supercapacitor 12, the power electronic converter 13, the current sensor 14 and the charging mode controller 16, and is used to generate a control command CTRL and a current command IMON_OUT according to the first sensing voltage ISENSE+, the second sensing voltage ISENSE- and the total feedback FB_OUT. Specifically, the voltage step-up/down controller 15 calculates the charging current of the supercapacitor 12 according to the voltage difference between the first sensing voltage ISENSE+ and the second sensing voltage ISENSE- and the equivalent resistance value of the resistor RS. Then, the voltage boost controller 15 provides a control command CTRL to the power electronic converter 13 to adjust the output voltage and output current according to the charging current of the supercapacitor 12 and the total feedback FB_OUT, and provides a current command IMON_OUT to the charging mode controller 16 to adjust the total feedback FB_OUT.

The charging mode controller 16 is coupled to the power supply 11, the supercapacitor 12 and the voltage step-up controller 15, and is used to provide current feedback FB1 and voltage feedback FB2 according to the driving voltage CV, the current command IMON_OUT and the third sense voltage VSENSE. It is worth noting that the third sense voltage VSENSE from the supercapacitor 12 and the current feedback FB1 and voltage feedback FB2 from the charging mode controller 16 are summed and input to the same input terminal of the voltage step-up controller 15 as the total feedback FB_OUT, that is, FB_OUT=VSENSE+FB1+FB2. In one embodiment, the lines for transmitting the third sense voltage VSENSE, the current feedback FB1 and the voltage feedback FB2 are electrically connected or short-circuited to the same input terminal of the voltage step-up controller 15.

The constant current controller 16A is coupled to the power supply 11 and the voltage step-up/down controller 15 to generate a current feedback FB1 according to the driving voltage CV and the current command IMON_OUT. The constant voltage controller 16B is coupled to the power supply 11 and the super capacitor 12 to generate a voltage feedback FB2 according to the driving voltage CV and the third sensing voltage VSENSE.

In operation, at the beginning of charging, the third sense voltage VSENSE is zero volts. When the charging mode controller 16 is powered on and started, the constant voltage controller 16B generates a voltage feedback FB2 to the voltage step-up controller 15 according to the driving voltage CV, so that the voltage step-up controller 15 generates a control command CTRL to the power electronic converter 13 to start charging the supercapacitor 12. Then, the voltage step-up controller 15 generates a current command IMON_OUT to the constant current controller 16A according to the first sense voltage ISENSE+, the second sense voltage ISENSE- and the total feedback FB_OUT, so that the constant current controller 16A generates a current feedback FB1 according to the driving voltage CV and the current command IMON_OUT. At the same time, the constant voltage controller 16B continues to generate a voltage feedback FB2 according to the driving voltage CV and the third sensing voltage VSENSE.

It is worth noting that, since the third sensing voltage VSENSE, the current feedback FB1 and the voltage feedback FB2 are summed and input to the voltage step-up controller 15, the storage capacity of the supercapacitor 12 observed by the voltage step-up controller 15 will be higher than the actual storage capacity. Assuming that at the initial stage of charging, the storage capacity of the supercapacitor 12 is zero volt (i.e., the third sensing voltage VSENSE is zero volt), the voltage step-up controller 15 will consider the storage capacity of the supercapacitor 12 to be the voltage feedback FB2 (or the sum of the current feedback FB1 and the voltage feedback FB2), so the voltage step-up controller 15 controls the power electronic converter 13 to charge the supercapacitor 12 with a lower charging current and voltage. In this way, the present disclosure can prevent the supercapacitor 12 from generating a surge or inrush current at the initial charging stage (when the stored charge is zero volts), thereby protecting the internal components of the power system 10.

On the other hand, when the supercapacitor 12 is charged to a preset voltage or discharged, the charging mode controller 16 is turned off, and the voltage boost controller 15 controls the power electronic converter 13 to perform power conversion only according to the third sensing voltage VSENSE (ie, the actual stored energy).

In brief, the charging mode controller 16 of the present disclosure generates a voltage feedback FB2 to the voltage step-up controller 15 at the initial stage of charging (the storage capacity of the supercapacitor 12 is zero volts) to charge the supercapacitor 12 with a lower current; and when the supercapacitor 12 is charged to a preset level or discharged, the charging mode controller 16 is turned off so as not to affect the operation of the voltage step-up controller 15. In this way, the charging mode controller 16 of the present disclosure can avoid generating a surge or inrush current at the initial stage of charging without affecting the operation of the power system 10, so as to protect the internal components of the power system 10.

Please refer to FIG2 , which is a schematic diagram of a charging mode controller 16 according to a first embodiment of the present disclosure. The charging mode controller 16 includes a constant current controller 16A and a constant voltage controller 16B.

Structurally, the constant current controller 16A includes a resistor R1, an operational amplifier OP1, a diode D1, resistors R7, R8, R9, R10 and a capacitor C2. The operational amplifier OP1 includes a positive input terminal for receiving the current command IMON_OUT; a negative input terminal for receiving the first preset potential CC1; and an output terminal coupled to a first end of the resistor R1. The diode D1 includes an anode coupled to a second end of the resistor R1; and a cathode coupled to the voltage boost controller 15 and the constant voltage controller 16B, wherein the diode D1 is used to output the current feedback FB1 and block the external voltage current. The resistor R7 includes a first end coupled to a driving voltage CC, and a second end coupled to the negative input terminal of the operational amplifier OP1. The resistor R8 includes a first end coupled to the negative input end of the operational amplifier OP1, and a second end coupled to a ground voltage, wherein a first preset potential CC1 is generated by dividing the driving voltage CC by the resistors R7 and R8. The resistor R9 includes a first end coupled to the current command IMON_OUT, and a second end coupled to a first end of the resistor R10. The resistor R10 includes a first end coupled to the second end of the resistor R9, and a second end coupled to the positive input end of the operational amplifier OP1. The capacitor C2 is connected in parallel with the resistor R10 to block a DC current of the current command IMON_OUT.

In operation, at the beginning of charging, when the current command IMON_OUT is greater than the first preset potential CC1, the constant current controller 16A outputs the current feedback FB1, so that the voltage step-up and step-down controller 15 charges the supercapacitor 12 with a lower current; and until the supercapacitor 12 is charged to the preset potential, when the current command IMON_OUT is less than or equal to the first preset potential CC1, the constant current controller 16A is turned off so as not to affect the operation of the voltage step-up and step-down controller 15.

In one embodiment, the constant current controller 16A further includes a hysteresis circuit HY1, which can maintain a stable output voltage (i.e., reduce output voltage ripple) when the input voltage of the operational amplifier OP1 is interfered by noise. The hysteresis circuit HY1 includes a capacitor C1 and a resistor R2. The capacitor C1 is coupled between the negative input terminal of the operational amplifier OP1 and the resistor R2. A first end of the resistor R2 is coupled to the capacitor C1, and a second end of the resistor R2 is coupled to the second end of the resistor R1 and the anode of the diode D1.

In one embodiment, a person skilled in the art can select the size of resistors R7 and R8 according to application requirements to adjust the ratio between the driving voltage CC and the first preset potential CC1. In one embodiment, a person skilled in the art can select resistors R9 and R10 according to application requirements to adjust the voltage component of the current command IMON_OUT input to the operational amplifier OP1. In one embodiment, a filter capacitor Cf can be connected in parallel between the negative input terminal of the operational amplifier OP1 and the ground voltage to filter out high-frequency noise of the first preset potential CC1.

Structurally, the constant voltage controller 16B includes a comparator CP, a transistor M, resistors R11, R12, R13, R14, R15, R16 and a capacitor C3. The resistor R11 includes a first end coupled to the third sensing voltage VSENSE. The resistor R12 includes a first end coupled to a second end of the resistor R11, and a second end coupled to a ground voltage, wherein a fourth sensing voltage VSEN1 is generated by dividing the third sensing voltage VSENSE by the resistors R11 and R12. The resistor R13 includes a first end coupled to the driving voltage CV. The resistor R14 includes a first end coupled to a second end of the resistor R13, and a second end coupled to the ground voltage, wherein a second preset potential CV2 is generated by dividing the driving voltage CV by the resistor R13 and the resistor R14. The capacitor C3 includes a first end coupled to the fourth sensing voltage VSEN1, and a second end coupled to the second preset potential CV2. The comparator CP includes a positive input end for receiving the fourth sensing voltage VSEN1; a negative input end for receiving the second preset potential CV2; and an output end coupled to a third preset potential VS3, the ground voltage and a gate of the transistor M. The transistor M includes a gate for receiving a third preset potential VS3 or a ground voltage; a source coupled to the ground voltage; and a drain coupled to a fourth preset potential VS4 and a first end of a resistor R3. The resistor R15 includes a first end coupled to a driving voltage VS. The resistor R16 includes a first end coupled to a second end of the resistor R15 and a gate of the transistor M, and a second end coupled to the ground voltage and a source of the transistor M, wherein the third preset potential VS3 is generated by dividing the driving voltage VS by the resistor R15 and the resistor R16.

In operation, at the beginning of charging, when the fourth sensing voltage VSEN1 is less than the second preset potential CV2, the gate of transistor M receives the ground voltage to turn off transistor M, so that the charging circuit 10A performs a first constant power charging mode. Until the supercapacitor 12 is charged to the preset potential, when the fourth sensing voltage VSEN1 is greater than or equal to the second preset potential CV2, the gate of transistor M receives the third preset potential VS3 to turn on transistor M, so that the charging circuit 10A performs a second constant power charging mode.

The constant voltage controller 16B further includes an operational amplifier OP2, a diode D2, and resistors R3, R4, R5, R17, and R18. The resistor R17 includes a first end coupled to the driving voltage VS. The resistor R18 includes a first end coupled to a second end of the resistor R17 and the drain of the transistor M, and a second end coupled to the ground voltage, wherein the fourth preset potential VS4 is generated by dividing the driving voltage VS by the resistor R17 and the resistor R18. The operational amplifier OP2 includes a positive input end coupled to a second end of the resistor R3; a negative input end coupled to a second end of the resistor R4; and an output end coupled to a first end of the resistor R4. The resistor R4 includes a first end coupled to the output end of the operational amplifier OP2, and a second end coupled to the negative input end of the operational amplifier OP2 and a first end of a resistor R5. The diode D2 includes an anode coupled to a second end of the resistor R5; and a cathode coupled to the voltage step-up controller 15 and the constant voltage controller 16B, for outputting the voltage feedback FB2 and blocking the external voltage current.

In operation, during the first constant power charging mode, the driving voltage VS is divided by resistors R17 and R18 and limited by resistor R3 to generate a fifth preset potential CV5, which is input to the positive input terminal of the operational amplifier OP2. The operational amplifier OP2 can be used as a voltage follower to gradually pull up the potential of the output terminal and the negative input terminal to the potential of the positive input terminal. That is, during the first constant power charging mode, when the transistor M is turned off, the positive input terminal of the operational amplifier OP2 receives the fifth preset potential CV5 to gradually pull up the voltage feedback FB2, so that the voltage boost controller 15 charges the super capacitor 12 at the first constant power. During the second constant power charging mode, transistor M is turned on to gradually pull down the positive input terminal of operational amplifier OP2 from the fifth preset potential CV5 to the ground voltage, so that the voltage boost controller 15 charges the super capacitor 12 at the second constant power. When the negative input terminal of operational amplifier OP2 is pulled down to the ground voltage, the constant voltage controller 16B is turned off so as not to affect the operation of the voltage boost controller 15. That is, when transistor M is turned on, the positive input terminal of operational amplifier OP2 receives the ground voltage to gradually reduce the voltage feedback FB2 until the charging circuit 10A is turned off.

In one embodiment, the constant voltage controller 16B further includes a hysteresis circuit HY2, which can maintain a stable output voltage (i.e., reduce the output voltage ripple) when the input voltage of the comparator CP is interfered by noise. The hysteresis circuit HY2 includes a resistor R6 and a diode D3. A first end of the resistor R6 is coupled to the negative input end of the comparator CP, and a second end of the resistor R6 is coupled to a cathode of a diode D3. An anode of the diode D3 is coupled to the output end of the comparator CP.

In one embodiment, a person skilled in the art can select the size of resistors R13 and R14 according to application requirements to adjust the ratio between the driving voltage CV and the second preset potential CV2. In one embodiment, a person skilled in the art can select the size of resistors R15 and R16 according to application requirements to adjust the ratio between the driving voltage VS and the third preset potential VS3. In one embodiment, a person skilled in the art can select the size of resistors R17 and R18 according to application requirements to adjust the ratio between the driving voltage VS and the fourth preset potential VS4. In one embodiment, a person skilled in the art can select resistors R11 and R12 according to application requirements to adjust the ratio between the third sensing voltage VSENSE and the fourth sensing voltage VSEN1. In one embodiment, the driving voltages CC, VS and CV can be substantially the same, and by selecting the ratio between the voltage divider resistors, a single driving voltage can be converted into multiple preset potentials that meet application requirements; in another embodiment, the driving voltages CC, VS and CV can be substantially different, and a person skilled in the art can select the size of the driving voltages CC, VS and CV according to application requirements. The driving voltage CC corresponds to the constant current characteristic, the driving voltage CV corresponds to the constant voltage characteristic, and the driving voltage VS corresponds to the voltage signal characteristic of the voltage feedback FB2.

In one embodiment, another filter capacitor Cf may be connected in parallel between the comparator CP and the ground voltage to filter out high-frequency noise of the fourth sensing voltage VSEN1. In one embodiment, multiple filter capacitors Cf may be connected in parallel between the positive input terminal of the operational amplifier OP2 and the ground voltage to filter out high-frequency noise of the second preset potential CV2, the fourth preset potential VS4, and the fifth preset potential CV5, respectively.

In one embodiment, the transistor M may be an insulated gate bipolar transistor (IGBT), a metal-oxide semiconductor field effect transistor (MOSFET), or other suitable power transistors.

Please refer to FIG3, which is a schematic diagram of a charging mode controller 36 according to a second embodiment of the present disclosure. The charging mode controller 36 can replace the charging mode controller 16 of FIG1 and FIG2, and includes a constant current controller 36A, a constant voltage controller 36B and a voltage conversion unit 36C.

Structurally, the voltage conversion unit 36C is coupled to the power supply 11 and the super capacitor 12 to generate a first preset potential CC1 according to the driving voltage CC, to generate a fourth sensing voltage VSEN1 according to the third sensing voltage VSENSE, to generate a second preset potential CV2 according to the driving voltage CV, and to generate a third preset potential VS3 and a fourth preset potential VS4 according to the driving voltage VS. The constant current controller 36A is coupled to the voltage conversion unit 36C and the voltage step-up controller 15 to generate a current feedback FB1 to the voltage step-up controller 15 according to the first preset potential CC1 and the current command IMON_OUT. The constant voltage controller 36B is coupled to the voltage conversion unit 36C, the voltage step-up and step-down controller 15 and the super capacitor 12 to generate a voltage feedback FB2 to the voltage step-up and step-down controller 15 according to the first preset potential CC1 and the fourth sense voltage VSEN1.

It is worth noting that the resistors R7-R18, capacitor C2, multiple filter capacitors Cf and other equivalent components of FIG. 2 can be integrated into the voltage conversion unit 36C, so that the circuit design of the constant current controller 36A and the constant voltage controller 36B of FIG. 3 is more concise than the circuit design of FIG. 2. In one embodiment, the voltage conversion unit 36C can be integrated into the power supply 11.

The constant current controller 36A includes a resistor R1, an operational amplifier OP1 and a diode D1. The operational amplifier OP1 includes a positive input terminal for receiving the current command IMON_OUT; a negative input terminal for receiving the first preset potential CC1; and an output terminal coupled to a first terminal of the resistor R1. The diode D1 includes an anode coupled to a second terminal of the resistor R1; and a cathode coupled to the voltage boost controller 15 and the constant voltage controller 36B, which is used to output the current feedback FB1 and block the external voltage current.

In operation, when the current command IMON_OUT is greater than the first preset potential CC1, the constant current controller 36A outputs the current feedback FB1; and when the current command IMON_OUT is less than or equal to the first preset potential CC1, the constant current controller 36A is turned off.

In one embodiment, the constant current controller 36A further includes a hysteresis circuit HY1, and the hysteresis circuit HY1 includes a capacitor C1 and a resistor R2. The capacitor C1 is coupled between the negative input terminal of the operational amplifier OP1 and the resistor R2; a first terminal of the resistor R2 is coupled to the capacitor C1, and a second terminal of the resistor R2 is coupled to the second terminal of the resistor R1 and the anode of the diode D1.

Structurally, the constant voltage controller 36B includes a comparator CP and a transistor M. The comparator CP includes a positive input terminal for receiving a fourth sensing voltage VSEN1; a negative input terminal for receiving a second preset potential CV2; and an output terminal coupled to the second preset potential CV2, a ground voltage, and a gate of the transistor M. The transistor M includes a gate for receiving a third preset potential VS3 or a ground voltage; a source coupled to the ground voltage; and a drain coupled to a fourth preset potential VS4 and a first end of a resistor R3. When the fourth sensing voltage VSEN1 is less than the second preset potential CV2, the gate of the transistor M receives the ground voltage to turn off the transistor M, so that the charging circuit 10A performs a first constant power charging mode. When the fourth sensing voltage VSEN1 is greater than or equal to the second preset potential CV2, the gate of the transistor M receives the third preset potential VS3 to turn on the transistor M, so that the charging circuit 10A performs a second constant power charging mode.

The constant voltage controller 36B includes an operational amplifier OP2, a diode D2, and resistors R3, R4, and R5. The operational amplifier OP2 includes a positive input terminal coupled to a second terminal of the resistor R3; a negative input terminal for receiving a fifth preset potential CV5, wherein the fourth preset potential VS4 generates the fifth preset potential CV5 after current limiting by the resistor R3; and an output terminal coupled to a first terminal of the resistor R4. The resistor R4 includes a first terminal coupled to the output terminal of the operational amplifier OP2, and a second terminal coupled to the negative input terminal of the operational amplifier OP2 and a first terminal of the resistor R5. The diode D2 includes an anode coupled to a second terminal of the resistor R5; and a cathode coupled to the voltage step-up and step-down controller 15 and the constant voltage controller 36B, for outputting the voltage feedback FB2 and blocking the external voltage current.

In operation, during the first constant power charging mode, the transistor M is turned off, and the constant voltage controller 36B gradually pulls up the voltage feedback FB2 according to the fifth preset potential CV5, so that the voltage boost controller 15 charges the super capacitor 12 with the first constant power. During the second constant power charging mode, the transistor M is turned on to gradually pull down the positive input terminal of the operational amplifier OP2 from the fifth preset potential CV5 to the ground voltage, so that the voltage boost controller 15 charges the super capacitor 12 with the second constant power. When the negative input terminal of the operational amplifier OP2 is pulled down to the ground voltage, the constant voltage controller 36B is turned off so as not to affect the operation of the voltage boost controller 15. That is, when the transistor M is turned on, the positive input terminal of the operational amplifier OP2 receives the ground voltage to gradually reduce the voltage feedback FB2 until the charging circuit 10A is turned off.

In one embodiment, the constant voltage controller 36B further includes a hysteresis circuit HY2, and the hysteresis circuit HY2 includes a resistor R6 and a diode D3. A first end of the resistor R6 is coupled to the negative input end of the comparator CP, and a second end of the resistor R6 is coupled to a cathode of the diode D3; an anode of the diode D3 is coupled to the output end of the comparator CP.

FIG4 is a flow chart of a charging method 40 for a supercapacitor according to an embodiment of the present disclosure. The charging method 40 can be performed by the charging circuit 10A and includes the following steps.

Step S40: providing the driving voltage CV, the current command IMON_OUT and the third sense voltage VSENSE to the charging mode controller 16 (or the charging mode controller 36).

Step S41: converting the driving voltage CV into the first preset potential CC1 and the second preset potential CV2, and converting the third sensing voltage VSENSE into the fourth sensing voltage VSEN1.

Step S42: Determine whether the fourth sensing voltage VSEN1 is less than the second preset voltage CV2. If yes, proceed to step S43; if no, proceed to step S44.

Step S43: Perform the first constant power charging mode. Return to step S42.

Step S44: Perform the second constant power charging mode.

Step S45: Determine whether the current command IMON_OUT is less than the first preset voltage CC1. If yes, proceed to step S46; if no, return to step S44.

Step S46: Perform constant voltage charging mode.

In step S43, the charging mode controller 16 (or the charging mode controller 36) provides both current feedback FB1 and voltage feedback FB2, and the third sense voltage VSENSE from the supercapacitor 12 and the current feedback FB1 and voltage feedback FB2 from the charging mode controller 16 (or the charging mode controller 36) are summed up and input to the same input terminal of the voltage step-up controller 15 to perform the first constant power charging mode. In step S44, the charging mode controller 16 (or the charging mode controller 36) only provides voltage feedback FB2, and the third sense voltage VSENSE from the supercapacitor 12 and the voltage feedback FB2 from the charging mode controller 16 (or the charging mode controller 36) are summed up and input to the same input terminal of the voltage step-up controller 15 to perform the second constant power charging mode. For details of the charging method 40, please refer to the relevant descriptions of FIG. 2 and FIG. 3, which will not be elaborated here.

FIG5 is a signal waveform diagram of the power system 10 of FIG1 during the charging of the supercapacitor 12, wherein curve 51 is the output voltage of the power electronic converter 13, curve 52 is the third sense voltage VSENSE (i.e., the storage capacity of the supercapacitor 12), and curve 53 is the output current of the power electronic converter 13. As shown in FIG5, between time points T1 and T2, the charging circuit 10A performs a first constant power charging mode, wherein the charging current and voltage of the supercapacitor 12 are substantially fixed, and the third sense voltage VSENSE rises substantially at a first rate. Between time points T2 and T3, the charging circuit 10A performs a second constant power charging mode, wherein the third sense voltage VSENSE rises substantially at a second rate (the first rate is greater than the second rate). After time point T3, the charging mode controller 16 (or charging mode controller 36) is turned off, and the charging circuit 10A enters the constant voltage charging mode until the supercapacitor 12 is fully charged.

In summary, the charging mode controller disclosed in the present invention generates total feedback to the voltage step-up and step-down controller at the initial stage of charging (when the supercapacitor has a storage capacity of zero volts) so as to charge the supercapacitor with a lower current; and when the supercapacitor is charged to a preset level or discharged, the charging mode controller is turned off so as not to affect the operation of the voltage step-up and step-down controller. The disclosed embodiments have at least the following advantages: (1) the charging mode controller disclosed herein can avoid generating surge or inrush current at the initial stage of charging to protect the internal components of the power system; (2) unlike the existing voltage step-up/step-down controller that controls charging based solely on the storage capacity of the supercapacitor, the total feedback disclosed herein includes signal components of current feedback and voltage feedback, thereby improving control accuracy; and (3) the induction current sensor is disposed after the energy storage inductor of the power electronic converter to avoid sensing noise at the input end of the power supply.

Although the present disclosure has been disclosed as above by way of embodiments, any person having ordinary knowledge in the relevant technical field may make some changes and modifications without departing from the spirit and scope of the present disclosure. Therefore, the protection scope of the present disclosure shall be determined by the scope of the attached patent application.

10: Power system 10A: Charging circuit 11: Power supply 12: Super capacitor 13: Power electronic converter 14: Current sensor 15: Voltage boost controller 16,36: Charging mode controller 16A,36A: Constant current controller 16B,36B: Constant voltage controller 36C: Voltage conversion unit 40: Charging method 51,52,53: Curve C1~C3: Capacitor CC,CV,VS: Driving voltage CC1: First preset potential Cf: Filter capacitor CP: Comparator CTRL: Control command CV2: Second preset potential CV5: Fifth preset potential D1,D2,D3: Diode FB_OUT: total feedback FB1: current feedback FB2: voltage feedback HY1,HY2: hysteresis circuit IMON_OUT: current command ISENSE+: first sensing voltage ISENSE-: second sensing voltage M: transistor OP1,OP2: operational amplifier R1~R18,RS: resistor S40~S46: step VS3: third preset voltage VS4: fourth preset voltage VSEN1: fourth sensing voltage VSENSE: third sensing voltage

In order to more fully understand the embodiments and their advantages, reference is now made to the following description in conjunction with the attached figures. FIG. 1 is a block diagram of an electric power system according to an embodiment of the present disclosure. FIG. 2 is a schematic diagram of a charging mode controller according to a first embodiment of the present disclosure. FIG. 3 is a schematic diagram of a charging mode controller according to a second embodiment of the present disclosure. FIG. 4 is a flow chart of a supercapacitor charging method according to an embodiment of the present disclosure. FIG. 5 is a signal waveform diagram of a supercapacitor during charging according to an embodiment of the present disclosure.

10: Power system

10A: Charging circuit

11: Power supply

12:Supercapacitor

13: Power electronic converter

14:Electromagnetic flow detector

15: Voltage boost controller

16: Charging mode controller

16A: Constant current controller

16B: Constant voltage controller

CTRL: Control command

CV: driving voltage

FB_OUT: total feedback

FB1: Current feedback

FB2: Voltage feedback

IMON_OUT: Current command

ISENSE+: First sensing voltage

ISENSE-: Second sensing voltage

RS:resistance

VSENSE: Third sensing voltage

Claims (16)

A charging circuit for charging or discharging a supercapacitor comprises: a power electronic converter for charging or discharging the supercapacitor according to a control command; an inductive flow sensor coupled to the supercapacitor for sensing a first sensing voltage and a second sensing voltage; a voltage step-up and step-down controller coupled to the supercapacitor, the power electronic converter and the inductive flow sensor for sensing a first sensing voltage, a second sensing voltage and a total feedback voltage. to generate the control command and a current command; and a charging mode controller coupled to the supercapacitor and the voltage step-up controller, for generating a current feedback and a voltage feedback to the voltage step-up controller according to a driving voltage, the current command and a third sensing voltage of the supercapacitor; wherein the third sensing voltage, the current feedback and the voltage feedback are summed up and input to the same input terminal of the voltage step-up controller as the total feedback. A charging circuit as described in claim 1, wherein the charging mode controller comprises: a voltage conversion unit coupled to a power supply and the supercapacitor, for generating a first preset potential, a second preset potential, a third preset potential and a fourth preset potential according to the driving voltage, and for generating a fourth sensing voltage according to the third sensing voltage; a constant current controller coupled to the voltage conversion unit and the voltage step-up and step-down controller, which is used to generate the current feedback to the voltage step-up and step-down controller according to the first preset potential and the current command; and a certain voltage controller, which is coupled to the voltage conversion unit, the voltage step-up and step-down controller and the supercapacitor, which is used to generate the voltage feedback to the voltage step-up and step-down controller according to the second preset potential, the third preset potential, the fourth preset potential and the fourth sensing voltage. A charging circuit as described in claim 2, wherein the constant current controller comprises: a first resistor; a first operational amplifier, comprising: a positive input terminal for receiving the current command; a negative input terminal for receiving the first preset potential; and an output terminal coupled to a first terminal of the first resistor; a first diode, comprising: an anode coupled to a second terminal of the first resistor; and a cathode coupled to the voltage step-up controller and the constant voltage controller for outputting the current feedback; wherein, when the current command is greater than the first preset potential, the constant current controller outputs the current feedback; and when the current command is less than or equal to the first preset potential, the constant current controller is turned off. The charging circuit as described in claim 3, wherein the constant current controller further includes a first hysteresis circuit, the first hysteresis circuit includes a first capacitor and a second resistor, wherein: the first capacitor is coupled between the negative input terminal of the first operational amplifier and the second resistor; a first end of the second resistor is coupled to the first capacitor, and a second end of the second resistor is coupled to the second end of the first resistor and the anode of the first diode. A charging circuit as described in claim 3, wherein the constant voltage controller comprises: a comparator, comprising: a positive input terminal for receiving the fourth sensing voltage; a negative input terminal for receiving the second preset potential; and an output terminal coupled to the first preset potential, a ground voltage and a gate of a transistor; the transistor comprises: the gate for receiving the third preset potential or the ground voltage; a source coupled to the ground voltage; and a drain coupled to the first preset potential, a ground voltage and a drain. The fourth preset potential and a first end of a third resistor; wherein, when the fourth sensing voltage is less than the second preset potential, the gate of the transistor receives the ground voltage to turn off the transistor, so that the charging circuit performs a first constant power charging mode; when the fourth sensing voltage is greater than or equal to the second preset potential, the gate of the transistor receives the third preset potential to turn on the transistor, so that the charging circuit performs a second constant power charging mode. A charging circuit as described in claim 5, wherein the constant voltage controller comprises: the third resistor; a second operational amplifier comprising: a positive input terminal coupled to a second terminal of the third resistor; a negative input terminal for receiving a fifth preset potential, wherein the fourth preset potential is generated after the third resistor limits the current; and an output terminal; a fourth resistor comprising a first terminal coupled to the output terminal of the second operational amplifier, and a second terminal coupled to the negative input terminal of the second operational amplifier and a fifth resistor. A first end; the fifth resistor; a second diode, comprising: an anode coupled to a second end of the fifth resistor; and a cathode coupled to the voltage step-up and step-down controller and the constant voltage controller, for outputting the voltage feedback; wherein, when the transistor is turned off, the positive input end of the second operational amplifier receives the fifth preset potential to gradually pull up the voltage feedback; when the transistor is turned on, the positive input end of the second operational amplifier receives the ground voltage to gradually reduce the voltage feedback until the charging circuit is turned off. The charging circuit as described in claim 6, wherein the constant voltage controller further comprises a second hysteresis circuit, the second hysteresis circuit comprises a sixth resistor and a third diode, wherein: a first end of the sixth resistor is coupled to the negative input end of the comparator, and a second end of the sixth resistor is coupled to a cathode of the third diode; an anode of the third diode is coupled to the output end of the comparator. The charging circuit as described in claim 1, wherein the charging mode controller includes: a constant current controller coupled to a power supply and the voltage step-up controller, for generating the current feedback to the voltage step-up controller according to a first preset potential and the current command; and a constant voltage controller coupled to the power supply, the voltage step-up controller and the supercapacitor, for generating the voltage feedback to the voltage step-up controller according to a second preset potential, a third preset potential, a fourth preset potential and the third sensing voltage. A charging circuit as described in claim 8, wherein the constant current controller comprises: a first resistor; a first operational amplifier, comprising: a positive input terminal for receiving the current command; a negative input terminal for receiving the first preset potential; and an output terminal coupled to a first terminal of the first resistor; a first diode, comprising: an anode coupled to a second terminal of the first resistor; and a cathode coupled to the voltage step-up controller and the constant voltage controller for outputting the current feedback; a seventh resistor, comprising a first terminal coupled to the driving voltage, and a second terminal coupled to the negative input terminal of the first operational amplifier; an eighth resistor, comprising a first terminal coupled to the negative input terminal of the first operational amplifier , and a second end coupled to a ground voltage, wherein the first preset potential is generated by dividing the driving voltage by the seventh resistor and the eighth resistor; a ninth resistor, including a first end coupled to the current command, and a second end coupled to a first end of a tenth resistor; the tenth resistor, including a first end coupled to the second end of the ninth resistor, and a second end coupled to the positive input end of the first operational amplifier; a second capacitor, connected in parallel with the tenth resistor, to block a DC current of the current command; wherein, when the current command is greater than the first preset potential, the constant current controller outputs the current feedback; and when the current command is less than or equal to the first preset potential, the constant current controller is turned off. A charging circuit as described in claim 9, wherein the constant current controller further includes a first hysteresis circuit, the first hysteresis circuit includes a first capacitor and a second resistor, wherein: The first capacitor is coupled between the negative input terminal of the first operational amplifier and the second resistor; a first end of the second resistor is coupled to the first capacitor, and a second end of the second resistor is coupled to the second end of the first resistor and the anode of the first diode. A charging circuit as described in claim 9, wherein the constant voltage controller comprises: an eleventh resistor, comprising a first end coupled to the third sensing voltage; a twelfth resistor, comprising a first end coupled to a second end of the eleventh resistor, and a second end coupled to a ground voltage, wherein a fourth sensing voltage is generated by voltage division of the eleventh resistor and the twelfth resistor; a thirteenth resistor, comprising a first end coupled to the driving voltage; a fourteenth resistor, comprising a fourth sensing voltage; a first terminal coupled to a second terminal of the thirteenth resistor, and a second terminal coupled to the ground voltage, wherein the second preset potential is generated by voltage division between the thirteenth resistor and the fourteenth resistor; a third capacitor, comprising a first terminal coupled to the fourth sensing voltage, and a second terminal coupled to the first preset potential; a comparator, comprising: a positive input terminal for receiving the fourth sensing voltage; a negative input terminal for receiving the second preset potential; and an output terminal coupled to the fourth sensing voltage; three preset potentials, a ground voltage and a gate of a transistor; the transistor comprises: the gate for receiving the third preset potential or the ground voltage; a source coupled to the ground voltage; and a drain coupled to the first preset potential and a first end of a third resistor; a fifteenth resistor comprising a first end coupled to the driving voltage; a sixteenth resistor comprising a first end coupled to a second end of the fifteenth resistor and the gate of the transistor, and a The second end is coupled to the ground voltage and the source of the transistor; wherein, when the fourth sensing voltage is less than the second preset potential, the gate of the transistor receives the ground voltage to turn off the transistor, so that the charging circuit performs a first constant power charging mode; when the fourth sensing voltage is greater than or equal to the second preset potential, the gate of the transistor receives the third preset potential to turn on the transistor, so that the charging circuit performs a second constant power charging mode. The charging circuit as claimed in claim 11, wherein the constant voltage controller further comprises: a seventeenth resistor, comprising a first end coupled to the driving voltage; an eighteenth resistor, comprising a first end coupled to a second end of the seventeenth resistor and the drain of the transistor, and a second end coupled to the ground voltage; the third resistor; a second operational amplifier, comprising: a positive input end coupled to a second end of the third resistor; a negative input end for receiving a fifth preset potential, wherein the driving voltage is divided by the seventeenth resistor and the eighteenth resistor and the third resistor is used to limit the current to generate the fifth preset potential; and an output end coupled to a first end of the first resistor; a fourth resistor , comprising a first end coupled to the output end of the second operational amplifier, and a second end coupled to the negative input end of the second operational amplifier and a first end of a fifth resistor; the fifth resistor; a second diode, comprising: an anode coupled to a second end of the fifth resistor; and a cathode coupled to the voltage step-up controller and the constant voltage controller, for outputting the voltage feedback; wherein, when the transistor is turned off, the positive input end of the second operational amplifier receives the fifth preset potential to gradually pull up the voltage feedback; when the transistor is turned on, the positive input end of the second operational amplifier receives the ground voltage to gradually reduce the voltage feedback until the charging circuit is turned off. A charging circuit as described in claim 12, wherein the constant voltage controller further comprises a second hysteresis circuit, the second hysteresis circuit comprises a sixth resistor and a third diode, wherein: a first end of the sixth resistor is coupled to the negative input end of the comparator, and a second end of the sixth resistor is coupled to a cathode of the third diode; an anode of the third diode is coupled to the output end of the comparator. A charging circuit as described in claim 1, wherein: A first end of the current flow sensor is coupled to the power electronic converter to sense the first sensing voltage, and a second end of the current flow sensor is coupled to the super capacitor to sense the second sensing voltage; the voltage step-up and step-down controller is also used to calculate a charging current of the super capacitor according to the first sensing voltage, the second sensing voltage and an equivalent resistance value of the current flow sensor. A power system, comprising: a charging circuit as described in claim 1; a supercapacitor; and a power supply coupled to the charging circuit, for: providing a charging power source and a driving voltage to the charging circuit during charging, so that the charging circuit charges the supercapacitor according to the charging power source and the driving voltage; and storing power from the supercapacitor during discharge. A charging method, used in a charging circuit as described in claim 1, comprising: generating a current command according to a first sensing voltage, a second sensing voltage and a total feedback; providing a driving voltage, the current command and a third sensing voltage to a charging mode controller; converting the driving voltage to a first preset voltage, a second preset voltage, and converting the third sensing voltage to a fourth sensing voltage; When the fourth sensing voltage is less than the second preset voltage, performing a supercapacitor A first constant power charging mode; when the fourth sensed voltage is greater than or equal to the second preset potential, the supercapacitor is subjected to a second constant power charging mode; and when the current command is less than the first preset potential, the supercapacitor is subjected to a constant voltage charging mode; wherein the third sensed voltage of the supercapacitor, a current feedback and a voltage feedback generated by the charging mode controller are summed and input to the same input terminal of a voltage step-up and step-down controller as the total feedback.

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