CN204947671U - A kind of multifunctional electric energy meter battery charge circuit - Google Patents

Abstract

A kind of multifunctional electric energy meter battery charge circuit, is characterized in that, by rechargeable battery BT1, BT2, and button cell BT3, diode D1, D2, switch S 11, S12, S21 and S22, electric capacity C1, C2, resistance R, voltage detecting end UB1, UB2, UR form; The utility model has the following advantages and beneficial effect: solve current battery capacity check inaccurate, shallow fill shallowly to put, the problem such as on-line maintenance is few, poor universality, avoid electric energy meter due to outside have a power failure and battery electric quantity low and cause register data to lose, electricity cannot be recorded and cause economic loss.Improve the reliability of electric energy meter data, reduce manual maintenance cost.The 4 kinds of operating states that the utility model proposes regularly can carry out on-line maintenance to battery, and activated batteries dormancy electricity, extends the life-span of battery, effectively solve that battery is shallow fills shallow problem of putting, and reduce the impact of memory effect.

Description

A kind of multifunctional electric energy meter battery charge circuit

Technical field

The utility model belongs to Electric Energy Metering Technology, especially relates to a kind of multifunctional electric energy meter battery charge circuit.

Background technology

Electric energy meter is the important part of electric power meter, and electric energy meter is installed and used huge numbers of families, for the electricity charge clearing and collect.Electric energy consumption sharp increase in recent years, power department needs to have multi-purpose electric energy meter to be come fairer and more reasonable to collect electric energy expense, and better plans electrical energy production.Battery is the vitals in electric energy meter, the reliably working under relation electric energy extra-portion's power failure condition.The battery variety of onsite application is more, and charging management system must can carry out management of charging and discharging to the battery such as ni-mh, NI-G.

According to the requirement of electric energy meter associated specifications, after the complete power down of electric energy meter, rechargeable battery at least maintains internal time and register data is not less than 90 days, and the electric energy meter of particular/special requirement is held time and register data is 1 year.But in actual motion, part electric energy meter battery after a power failure voltage sharply declines, and cannot provide required electricity, has a strong impact on the accuracy of continuous data.In electric energy meter equipment mainly there is following problem in existing rechargeable battery management system:

1. calculate dump energy with cell voltage, truly cannot reflect dump energy, when battery capacity reduces, warning information cannot be sent in time, prompting changing battery.

2. lack battery maintenance function, when battery does not work for a long time, suitably cannot activate maintenance to battery, cause battery actual capacity significantly to reduce.

3. frequent charge, shortens battery.Most of electric energy meter adopts constant-voltage method to charge to battery, instead of when battery electric quantity just starts charging lower than during threshold value, causes battery frequent charge.

4. poor universality, the characteristic of different rechargeable batteries there are differences, and battery management system is only applicable to a certain type cell usually, cannot meet the requirement of battery interchangeability.

Summary of the invention

In order to solve the problem, extend battery, improve the stability and safety of electric energy meter standby power system, the utility model provides a kind of electric energy meter battery charge circuit, by rechargeable battery BT1, BT2, button cell BT3, diode D1, D2, switch S 11, S12, S21 and S22, electric capacity C1, C2, resistance R, voltage detecting end UB1, UB2, UR form.

Wherein, button cell BT3 positive pole connects diode D1 positive pole, BT3 negative pole connects diode D2 negative pole, rechargeable battery BT1 meets power supply U+ and U-by switch S 11, rechargeable battery BT2 meets power supply U+ and U-by switch S 21, electric capacity C1, C2 and resistance R parallel connection, be connected by switch S 12 in the middle of C1 with R, be connected by switch S 22 in the middle of C2 with R.

The utility model adopts the capacity of ampere-hour integration method assessment battery, first carries out charging to battery and makes voltage reach higher limit, then utilize resistance R to discharge, detect and recording voltage UB1, UB2, UR and discharge time t, until cell voltage is down to lower limit.Then the capacity of battery can be calculated by formula (1):

$C={\∫}_0^t\frac{U_R\left(\mathrm{\τ}\right)}{R}d\mathrm{\τ}---\left(1\right)$

Detect battery capacity compared to open circuit voltage method, the testing result of ampere-hour integration method is more accurate.

The current grid power blackout time is fewer and feweri, and operational reliability is very high, and electric energy meter in use interruption duration is less, and rechargeable battery is not in discharge condition for a long time.From the characteristic of Ni-MH battery and lithium battery, if battery does not carry out discharge and recharge for a long time, then its life-span can be affected.Therefore, after each charge and discharge cycles, record T standby time, when T exceedes threshold value Td, then needs to safeguard battery.Td according to the featured configuration of battery, generally can be set to 3 months.Nickel-cadmium cell, then due to " memory effect ", needs to carry out full maintenance electric discharge at set intervals, recovers battery performance.Consider the redundancy feature of battery, rechargeable battery BT1 and BT2 can not discharge simultaneously.Just allow after must completing the maintenance of a batteries to safeguard another batteries, ensure that electric energy meter has suitable electricity for subsequent use.When safeguarding, BT1 or BT2 all utilizes resistance R to discharge.By formula (2), discharging current i _rarranged by the duty ratio of switch S 12 or S22, can discharge to battery according to default discharge curve.

$i_R=\frac{U_{BT}\·D}{R}---\left(2\right)$

Current satisfactory ni-mh, nickel-cadmium cell there are differences in capacity, charge cutoff voltage etc.In order to the different types of battery of compatibility, meet the requirement of on-the-spot battery interchangeability, charging current is preferably set to 60mA, and the discharging current in maintenance state is preferably set to 120mA.Charge cutoff voltage is preferably set to 6.6V, and charged state is constant current voltage limiting.For reducing " memory effect " to the impact of battery capacity, charging lower voltage limit is preferably set to 4.4V.The battery discharge that dump energy is less is first selected during electric discharge, until voltage is down to 4.2V, then the battery discharge selecting dump energy larger.Because the electric energy meter overwhelming majority time is in externally fed state, therefore the charge circuit of electric energy meter battery does not pursue quick charge, but selects less charging current.

The utility model has the following advantages and beneficial effect: solve current battery capacity check inaccurate, shallow fill shallowly to put, the problem such as on-line maintenance is few, poor universality, avoid electric energy meter due to outside have a power failure and battery electric quantity low and cause register data to lose, electricity cannot be recorded and cause economic loss.Improve the reliability of electric energy meter data, reduce manual maintenance cost.The 4 kinds of operating states that the utility model proposes regularly can carry out on-line maintenance to battery, and activated batteries dormancy electricity, extends the life-span of battery, effectively solve that battery is shallow fills shallow problem of putting, and reduce the impact of memory effect.

Accompanying drawing explanation

Fig. 1 is circuit theory diagrams of the present utility model.

Embodiment

Below in conjunction with accompanying drawing, the technical solution of the utility model is clearly and completely described:

As shown in Figure 1, the utility model provides a kind of multifunctional electric energy meter battery charge circuit, by rechargeable battery BT1, BT2, button cell BT3, diode D1, D2, switch S 11, S12, S21 and S22, electric capacity C1, C2, resistance R, voltage detecting end UB1, UB2, UR form.

Wherein, button cell BT3 positive pole connects diode D1 positive pole, BT3 negative pole connects diode D2 negative pole, rechargeable battery BT1 meets power supply U+ and U-by switch S 11, rechargeable battery BT2 meets power supply U+ and U-by switch S 21, electric capacity C1, C2 and resistance R parallel connection, be connected by switch S 12 in the middle of C1 with R, be connected by switch S 22 in the middle of C2 with R.

Described voltage detecting end UB1 is for detecting rechargeable battery BT1 voltage.

Described voltage detecting end UB2 is for detecting rechargeable battery BT2 voltage.

Described voltage detecting end UR is for detecting resistance R voltage.

Described button cell BT3 preferred voltage is 6V.

Described rechargeable battery BT1, BT2 preferred voltage is 6V, and rated capacity is all greater than 500mAh.

The utility model has 4 kinds of operating states: normal condition, maintenance state, power-down state, guard mode.

One, normal condition

When electric energy meter externally fed is normal, management system runs on normal condition, realizes the charge function to battery.When switch S 11, S21 close, when S12, S22 disconnect, system is in normal condition.Now battery BT1, BT2 is connected to power supply U+ and U-two ends.Power supply U+ and U-can charge to battery, and charging current is arranged by the duty ratio of switch S 11, S21.When capacity or the dump energy difference of two batteries, different charging currents is set by switch S 11, S21, optimizes the charge efficiency of every batteries, shorten the overall charging interval.

Two, maintenance state

Maintenance state is that battery provides discharge loop.When switch S 11, S21, S22 disconnect, S12 close, or switch S 11, S12, S21 disconnect, when S22 closes, system is in maintenance state, and battery BT1 or BT2 discharges to load resistance R separately.The major function of maintenance state, one is for test battery capacity, and two is safeguard for the activation of battery.After battery uses for a long time, capacity can reduce, and therefore needs routine test battery capacity.

Three, power-down state

When electric energy meter externally fed is abnormal, the voltage of power supply U+ and U-is lower than settings, and preferred 4.2V, electric energy meter is in power-down state.Now switch S 12, S22 disconnect, and S11, S21 are closed, and battery BT1 and BT2 parallel connection is powered to electric energy meter.If when internal resistance difference comparatively greatly or voltage difference is larger when BT1 and BT2 is in parallel, may output effect be affected.By the discharging current regulating the duty ratio of S11 and S21 to arrange BT1 and BT2 respectively, the discharging current of balanced two batteries, improves the discharging efficiency under power-down state.

Four, guard mode

When switch S 11, S12, S21, S22 disconnect, system is in guard mode, and now battery BT1 and BT2 and electric energy meter electric source depart from completely.Detect the voltage of power supply U+ and U-, and detect the change in voltage of voltage detecting end UB1, UB2, UR.When electric energy meter causes power supply U+ and U-too high because external power source is disturbed (as surge impact, overvoltage), in order to protect BT1 and BT2 from excessive pressure damages, battery system enters guard mode.Treat that external power source recovers normal reverse and goes out guard mode.

If now complete power-down state appears in electric energy meter, power supply U+ and U-is in complete power-down state, and button cell BT3 is powered to electric energy meter by power supply U+ and U-, ensures that clock of power meter and register data are not lost.Button cell BT3 both positive and negative polarity place is provided with diode D1, D2, can not be subject to external power source surge impact, overvoltage is impacted or electromagnetic distu at guarantee BT3.

Claims (2)

1. a multifunctional electric energy meter battery charge circuit, is characterized in that, by rechargeable battery BT1, BT2, and button cell BT3, diode D1, D2, switch S 11, S12, S21 and S22, electric capacity C1, C2, resistance R, voltage detecting end UB1, UB2, UR form;

Wherein, button cell BT3 positive pole connects diode D1 positive pole, BT3 negative pole connects diode D2 negative pole, rechargeable battery BT1 meets power supply U+ and U-by switch S 11, rechargeable battery BT2 meets power supply U+ and U-by switch S 21, electric capacity C1, C2 and resistance R parallel connection, be connected by switch S 12 in the middle of C1 with R, be connected by switch S 22 in the middle of C2 with R.

2. a kind of multifunctional electric energy meter battery charge circuit according to claim 1, is characterized in that, described button cell BT3 preferred voltage is 6V.