JP2010075032A - Charging method and charging circuit for hybrid capacitor - Google Patents

Abstract

A hybrid capacitor has a weak point that it is difficult to rapidly charge and discharge compared to a normal electric double layer capacitor. In addition, sufficient measures against overdischarge / overcharge and overcurrent were required during charging and discharging. (Overcharge protection is required even for ordinary electric double layer capacitors) Furthermore, when a capacitor is used as a storage element, its voltage fluctuates greatly due to charging and discharging, and it is necessary to assemble a charging circuit, output stabilization circuit and protection circuit on the customer side Yes, the volume of the entire system was increased.
[MEANS FOR SOLVING PROBLEMS] 4. Fast charging is possible for a single hybrid capacitor cell. The protection circuit enables measures against overdischarge, overcharge, and overcurrent. Further 1. 2. Buck-boost converter; Output controller, 4. The charge controller can cope with an unstable input, and a stable output is possible. Further, by integrating all of these, the size of the device can be reduced.
[Selection] Figure 2

Description

Technology field

  The present invention relates to a method for charging a hybrid capacitor and a charging circuit.

  The hybrid capacitor combines the characteristics of both a secondary battery such as a lithium ion battery and an electric double layer capacitor.

  Since the hybrid capacitor has a larger internal resistance than the electric double layer capacitor, it is necessary to limit the charging current in order to increase the charging efficiency. Moreover, the minimum operating voltage exists like secondary batteries, such as lithium ion, and at the time of charge / discharge, measures against overdischarge are required in addition to overcharge / overcurrent. Further, like the electric double layer capacitor, there is a problem that the voltage of the capacitor greatly varies depending on the charging capacity.

(1) In accordance with the characteristics of the hybrid capacitor, a step-down converter is embedded and integrated so that the capacitor cell can be quickly charged and the input current is reduced and the conductor loss is minimized.
(2) An overdischarge / overcharge / overcurrent prevention circuit is embedded between capacitor terminals and integrated.
(3) A converter for supplying a stable voltage is embedded and integrated with respect to the output of the capacitor whose voltage changes depending on the charging capacity.
(4) By integrating and integrating the above (1), (2), and (3) between capacitor terminals, a power supply with a built-in capacitor with a quick charge function is safe and easy to use for everyone, and a small and long-life power supply. Can be provided.

  According to the present invention, the hybrid capacitor can be rapidly charged, and sufficient measures against overdischarge, overcharge, and overcurrent can be taken, so that safety can be ensured. Even when the input is unstable, the charging circuit functions normally and the output voltage can be output stably. Further, by integrating all of these, the size of the device can be reduced.

One embodiment of the present invention is shown in FIG.
A protection circuit that combines overcharge / overcurrent and backflow prevention and current control for a single cell of a hybrid capacitor, a charge converter for quick charge, a step-up / down converter that stabilizes the output, and an output controller that controls these The charge controller is embedded and integrated between the capacitor terminals and in the immediate vicinity thereof.

"Effect of the embodiment"
According to this embodiment, the hybrid capacitor can be rapidly charged even if the input voltage is unstable. The charge converter has a built-in overcharge / overcurrent protection function, and the output converter has a built-in overdischarge function to separate charge control and discharge control, and when the charge power supply is not connected, the charge circuit has a backflow from the capacitor. Is preventing. Therefore, even an unstable and irregular power source such as a solar cell can be handled by changing the program of the charge controller. In addition, the output converter can supply a stable rated output voltage if the output voltage is within the operating voltage range of the hybrid capacitor, and the output converter operates even if a short circuit occurs on the output side device. Protect the capacitor from damage. In addition, downsizing of the equipment can be achieved by integration and integration.

It is a circuit diagram which shows the example of a primary protection circuit of a lithium ion secondary battery. It is a circuit diagram showing one embodiment of this invention.

Explanation of symbols

1. 1. Buck-boost converter 2. Hybrid capacitor single cell Output controller 4. 4. Charge controller Protection circuit 6. Step-down converter FET1. Field effect transistor FET2. Field effect transistor FET3. Field effect transistor FET4. Field effect transistor

Claims (4)

A circuit equivalent to the primary protection of the lithium ion battery is embedded in the hybrid capacitor cell. (FIG. 1) Here, when the gate drive voltage of the switch elements FET1 and FET2 for cutting off the circuit is supplied from the capacitor cell, the gate voltage of the switch element becomes insufficient when the voltage of the capacitor cell decreases, The ON resistance of FET1 and FET2 increases. This increase in resistance value causes a voltage drop and heat generation, further causing a decrease in the gate voltage of FET1 and FET2, and the circuit becomes incompletely operated. In order to solve this problem and reduce the total loss by using the charging circuit backflow prevention element, as shown in Fig. 2, the charging circuit side also has overcharge protection + current detection and overcurrent protection + backflow prevention. These are FET3 and FET4. Current detection senses Vds of FET3 and FET4, thereby reducing current detection resistance and reducing loss. Also, FET3 and FET4 function as switches that prevent current from flowing in both directions by turning off both FET3 and FET4 by combining them in both directions as shown in FIG. For this reason, at the time of charging, when the capacitor voltage, current or other abnormality is detected, the FET 3 and FET 4 are turned off, so that the capacitor and the charging circuit can be opened and protected. In the state where FET3 and FET4 are ON, the Vds is sensed and fed back to the charging converter to control the charging current according to the quick charging program. Here, the drive for the charge converter and the FET3 and FET4 gate drive circuits are all supplied from the charge power supply, and are operated only when the charge power supply is connected, regardless of the voltage of the capacitor. Of course, FET3 and FET4 are OFF when the charging power supply is not connected, and backflow (more current) from the capacitor is prevented. The charge converter is a step-down current converter, and by charging the capacitor from a charging power source n times the capacitor voltage, only 1 / n times the current flowing in the capacitor flows, and the output of the capacitor and the step-down current converter is minimized. In this case, a voltage drop due to wiring = power loss can be reduced, and the charging power supply output line does not need to pass a large current, so that a general-purpose AC adapter or the like can be used as it is. For example, when a 12V charging power source for a hybrid capacitor of 4V to 2V is prepared, the magnification is n = 6 when the capacitor voltage is the minimum 2V and n = 3 when the capacitor voltage is 4V. Therefore, if it is desired to charge the capacitor at a constant current of 10 A, a charging power source of 4 V × 10 A = 40 W may be prepared, and an AC adapter of 40 W ÷ 12 V = 3.4 A may be used. In addition, when the voltage is 3.5 V or more, the AC adapter can be operated with a smaller one such as 30 W by being programmed to decrease the constant current stepwise or charging with constant power. What is important here is that if the power supply satisfies the charging power to the capacitor, the output voltage is not limited as long as the output voltage is in the range of the capacitor rated voltage + α or more and the maximum operating voltage of the charging circuit. Actually, a heavy-electric converter is assumed assuming a general-purpose power supply in the range of + 4.5V to + 30V = 5-24V, and it operates with a general-purpose power supply with a rating of 30W or more, greatly increasing the flexibility of customer choice and A flexible quick charging circuit that does not require a dedicated charger can be supplied. Naturally, it is compatible with car cigarette lighter power supplies, and by changing the quick charging program, it can also handle unstable power supplies such as solar cells. Next, in addition to the quick charge circuit having the above-mentioned degree of freedom, for the output stabilizing converter (FIG. 2) for stabilizing and outputting the output voltage of the hybrid capacitor, for the purpose of constantly monitoring the capacitor voltage, In the controller, an IC or microcomputer corresponding to the total operating voltage of the capacitor is embedded, and when an overdischarge is detected, the output converter is shut down to minimize the discharge loss. In addition, since the capacitor cell terminal is not exposed and the input / output terminals (charging power input terminal and output converter output terminal) are both protected by the charging converter and the output converter even if an external short circuit occurs, Capacitor primary protection and secondary protection can be combined, miniaturization, a large current path and elements can be minimized, and loss can be reduced. The connection between each circuit and the capacitor is directly connected between the capacitor terminals, is a case-integrated type, and the internal electrode is protected by the case. There are a total of four terminals that go to the outside, but the input terminal to the charging converter is a jack terminal in accordance with the general-purpose AC adapter, and the stabilized power output is a USB terminal for 5V output. (However, if there is a 12V output or other requirements, it can be changed to the required voltage and terminal.)

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