Power source device and charge controlling method to be used in same

• US 7,566,828 B2
• Filed: 05/12/2005
• Issued: 07/28/2009
• Est. Priority Date: 05/14/2004
• Status: Active Grant

• Current Assignee: Envision AESC Energy Devices Ltd.
• Original Assignee: NEC Tokin Corporation (Yageo Corporation)
• Inventors: Sasaki, Hiroshi
• Primary Examiner(s): Neckel; Alexa D
• Assistant Examiner(s): Gardner; Shannon
• Application Number:
  US11/127,296
• Publication Number:
  US 20050252546A1
• Time in Patent Office: 1,538 Days
• Field of Search: None
• US Class Current: 136/243
• CPC Class Codes: H02J 7/35 with light sensitive cells
• CPC Class Codes: H02S 40/38 Energy storage means, e.g. batteries, structurally associated with PV modules
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers
• CPC Class Codes: Y02E 70/30 Systems combining energy storage with energy generation of non-fossil origin
• CPC Class Codes: Y10S 136/293 Circuits

Abstract

A power source device is provided which is capable of charging a secondary cell in a stable manner even in an environment in which power generated by a solar cell varies due to changes in sunlight intensity and/or ambient temperatures. By power generated by a solar cell module, an electric double-layer capacitor is charged and, by using a charging voltage of the electric double-layer capacitor, a booster-type DC-DC (Direct Current-Direct Current) converter is driven. A charge on/off controlling circuit detects the voltage of the electric double-layer capacitor and, when the voltage exceeds a high level threshold voltage, keeps a charge controlling signal (output signal from a terminal) in an active mode and performs a charge starting operation and, after that, when the voltage of the electric double-layer capacitor reaches a low level threshold value, holds the charge controlling signal in a non-active mode and performs a charge stopping operation.

Claims

1. A power source device comprising:

a solar cell module;

an electric double-layer capacitor;

a first reverse-current preventing element and a current limiting element connected in series between the solar cell module and the electric double-layer capacitor;

an overvoltage protecting element connected in parallel with the electric double-layer capacitor;

a secondary cell pack;

a secondary cell charge controlling circuit connected to the secondary cell pack for controlling a charging current or voltage to the secondary cell pack, the secondary cell charge controlling circuit including a charge controlling switch and a gate switch, the charge controlling switch controlling a charging current to the secondary cell pack;

a DC Direct Current-DC converter connected in series with the electric double-layer capacitor and the charge controlling switch of the secondary cell charge controlling circuit to supply an electric current for charging the secondary cell pack; and

a charge on/off controlling circuit connected to the electric double-layer capacitor and controlling the secondary cell charge controlling circuit, the charge on/off controlling circuit including a capacitor detecting circuit and a gate switch controlling circuit powered by the DC-DC converter, the capacitor detecting circuit including a low voltage detector and a low voltage threshold VL reference voltage source, a high voltage detector and a high voltage threshold VH reference voltage source wherein VL<

VH, when the charging voltage of the electric double-layer capacitor is lower than the threshold voltage “

VL”

, a Low signal having a low level is output from an output terminal VDL of the low voltage detector and, when the charging voltage of the electric double-layer capacitor is higher than the threshold voltage “

VL”

, a High signal having a high level is output from an output terminal VDH of the high voltage detector, the threshold voltage “

VL”

having a hysteresis in a range between VL(−

) and VL(+) and, when the charging voltage of the electric double-layer capacitor is lower than the threshold voltage “

VH”

, a Low signal is output from the output terminal VDL of the low voltage detector and when the charging voltage of the electric double-layer capacitor is higher than the threshold voltage “

VH”

a High signal is output from an output terminal VDH of the high voltage detector, the threshold voltage “

VH”

having a hysteresis in a range between VH(−

) and VH(+), the gate switch controlling circuit including a set/reset flip-flop circuit and responsive to a signal from the VDL terminal to be reset and responsive to a signal from the VDH terminal to be set, an output of the set/reset flip-flop controlling the gate switch of the secondary cell charge controlling circuit.

2. The power source device according to claim 1, wherein the secondary cell charge controlling circuit further includes:

a charging method selecting switch connected to the charge controlling switch by the gate switch;

a second reverse-current preventing element and a charging current detecting element connected in series between the charge controlling switch and the secondary cell pack;

a charging voltage detecting element connected in parallel with the secondary cell pack;

a CC Constant Current charge controlling circuit connected to a first terminal of the charging method selecting switch, the CC charge controlling circuit being responsive to the charging current detecting element to control a current level of a gate of the charge controlling switch so that a charging current detected by the charging current detecting element becomes a specified constant current; and

a CV Constant Voltage charge controlling circuit connected to a second termnal of the charging method selecting switch, the CV charge controlling circuit being responsive to the charging voltage detecting element to control a voltage level of the gate of the charge controlling switch so that a charging current detected by the charging voltage detecting element becomes a specified constant voltage,

wherein the secondary cell charge controlling circuit can be put in states of three types of operations depending on a state of the switches including the gate switch and the charging method selecting switch.

3. A power source device according to claim 1, further comprising:

an output converter mounted in a back-stage in a secondary cell pack, the output converter including a second DC-DC converter and a third DC-DC converter, input terminals of the second and third DC-DC converters being commonly connected to a positive polarity terminal of the secondary cell pack;

a first load connected to an output of the second DC-DC converter; and

a second load connected to an output of the third DC-DC converter, wherein stabilized power is fed to the first and second loads from the second and third DC-DC converters.

4. The power source device according to claim 3, wherein the secondary cell charge controlling circuit further includes:

a charging method selecting switch connected to the charge controlling switch by the gate switch;

a second reverse-current preventing element and a charging current detecting element connected in series between the charge controlling switch and the secondary cell pack;

a charging voltage detecting element connected in parallel with the secondary cell pack;

a CC Constant Current charge controlling circuit connected to a first terminal of the charging method selecting switch, the CC charge controlling circuit being responsive to the charging current detecting element to control a current level of a gate of the charge controlling switch so that a charging current detected by the charging current detecting element becomes a specified constant current; and

a CV Constant Voltage charge controlling circuit connected to a second termnal of the charging method selecting switch, the CV charge controlling circuit being responsive to the charging voltage detecting element to control a voltage level of the gate of the charge controlling switch so that a charging current detected by the charging voltage detecting element becomes a specified constant voltage,

wherein the secondary cell charge controlling circuit can be put in states of three types of operations depending on a state of the switches including the gate switch and the charging method selecting switch.

5. A power source device according to claim 1, wherein the electric double layer capacitor comprises a main capacitor and a sub-capacitor, and wherein the overvoltage protecting device comprises a main capacitor overvoltage protecting element and a sub-capacitor overvoltage protecting element, and the reverse-current preventing element comprises a main capacitor reverse-current preventing element and a sub-capacitor reverse-current preventing element, the power source device further comprising:

a charging capacitor selecting circuit, the charging capacitor selecting circuit comprising a selection switch controlling circuit and a selecting switch, the selection switch controlling circuit controlling the selecting switch according to a selection switch control signal output from the charge on/off controlling circuit;

a capacitor charging voltage comparing circuit, the capacitor charging voltage comparing circuit comprising a comparator to compare a voltage of the main capacitor with a voltage of the sub-capacitor and to output a switch controlling signal; and

a sub-capacitor discharge controlling circuit, the sub-capacitor discharge controlling circuit comprising a discharge switch, a sub-capacitor voltage detecting circuit, and a discharge switch controlling circuit the discharge switch having a control terminal first and second contacts, the sub-capacitor voltage detecting circuit having a Vsub detector to compare a voltage of the sub-capacitor with a threshold voltage “

VS”

of a reference voltage source to output a switch controlling signal “

VDS”

to the discharge switch, wherein the Vsub detector has a hysteresis characteristic.

6. The power source device according to claim 5, wherein the secondary cell charge controlling circuit further includes:

a charging method selecting switch connected to the charge controlling switchby the gate switch;

a second reverse-current preventing element and a charging current detecting element connected in series between the charge controlling switch and the secondary cell pack;

a charging voltage detecting element connected in parallel with the secondary cell pack;

a CC Constant Current charge controlling circuit connected to a first terminal of the charging method selecting switch, the CC charge controlling circuit being responsive to the charging current detecting element to control a current level of a gate of the charge controlling switch so that a charging current detected by the charging current detecting element becomes a specified constant current; and

a CV Constant Voltage charge controlling circuit connected to a second termnal of the charging method selecting switch, the CV charge controlling circuit being responsive to the charging voltage detecting element to control a voltage level of the gate of the charge controlling switch so that a charging current detected by the charging voltage detecting element becomes a specified constant voltage,

wherein the secondary cell charge controlling circuit can be put in states of three types of operations depending on a state of the switches including the gate switch and the charging method selecting switch.