CN113241823A

CN113241823A - Voltage regulating circuit and method for simulating discharge characteristic of primary battery based on fixed duty ratio

Info

Publication number: CN113241823A
Application number: CN202110544543.XA
Authority: CN
Inventors: 任谦
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-05-19
Filing date: 2021-05-19
Publication date: 2021-08-10

Abstract

The invention provides a voltage regulating circuit and a method for the discharge characteristic of a primary battery, which comprises a lithium battery, a PWM (pulse width modulation) circuit with a fixed duty ratio and a power output circuit, wherein the lithium battery comprises a fixed duty ratio PWM circuit and a power output circuit; the fixed duty ratio PWM circuit is electrically connected with the lithium battery and the power output circuit, and the power output circuit is also electrically connected with the lithium battery; the fixed duty ratio PWM circuit converts the output voltage of the lithium battery into the analog set primary battery voltage by outputting the set fixed duty ratio to the power output circuit. The invention can avoid the loss caused by sudden power failure of the lithium battery.

Description

Voltage regulating circuit and method for simulating discharge characteristic of primary battery based on fixed duty ratio

Technical Field

The invention relates to the technical field of battery design, in particular to a voltage regulating circuit and a method for simulating the discharge characteristic of a primary battery based on a fixed duty ratio.

Background

Because the energy density of the lithium battery is far greater than that of the traditional primary battery, the lithium battery can be used for a longer time under the same volume instead of the traditional primary battery, the charging times are reduced, and the user experience is improved, so that A-type, AA-type, AAA-type, AAAA-type, C-type, D-type and SC-type batteries which replace the primary battery are available in the market.

The scheme of replacing a primary battery by the existing lithium battery is that the lithium battery is converted into a fixed 1.5 or 9V output through DC-DC conversion. One problem with this solution is that: the equipment uses the lithium battery of the existing scheme to replace the primary battery, so that the residual electric quantity information of the battery cannot be accurately acquired, and the risk of sudden power failure is caused. The specific reason is analyzed as follows:

the equipment that uses current primary battery, like wireless microphone, universal meter, hand-held type instrument, remote controller etc. all need carry out the electric quantity and detect, remind the user in advance when the low electric quantity appears or appears soon in equipment: the battery is required to be replaced in time when the battery is low, so that inconvenience, problems and even accidents caused by sudden power failure of the battery are avoided. At present, equipment powered by a primary battery is used for estimating and measuring electric quantity based on battery voltage, for example, the equipment powered by the primary battery is used for judging that the battery is in a full-charge state when the battery voltage is 1.5V, and judging that the battery is out of charge when the battery is reduced to 1.15V (the threshold value is slightly different due to different products), and the battery is reminded to be replaced in time when the voltage is possibly 1.2-1.3V. However, the conventional scheme that the lithium battery outputs 1.5V through DC-DC constant voltage is adopted, so long as the voltage of the battery can provide a DC-DC circuit for working, the voltage is stabilized at 1.5V, and when the lithium battery is not electrified, the DC-DC circuit directly turns off the output, so that the equipment is directly powered off.

That is, the existing scheme adopting constant voltage DC-DC output has the problems that the constant voltage output is 1.5V, but the voltage directly drops to 0V when the power is off, and the power is suddenly cut off due to no intermediate transition.

Disclosure of Invention

In view of the above, the present invention provides a voltage regulating circuit and method for primary battery discharge characteristics, which can avoid the loss caused by sudden power failure of the lithium battery.

The invention is realized by adopting the following scheme: a voltage regulation method for simulating the discharge characteristic of a primary battery based on a fixed duty ratio specifically comprises the following steps:

the output voltage of the lithium battery is converted into a set primary battery voltage according to a fixed duty ratio.

Further, the fixed duty cycle is calculated using the following equation:

fixed duty cycle = set nominal voltage of full charge of primary battery/nominal voltage of full charge of lithium battery.

Further, when a nominal 4.2V ternary lithium battery is used to simulate a 1.5V output primary battery, the duty cycle is fixed at 35.7% + -0.2%.

Further, when a 1.5V output primary battery is simulated by using a nominal 3.6V lithium iron phosphate battery, the duty ratio is fixed at 41.7% ± 0.2%.

The invention also provides a voltage regulating circuit for simulating the discharge characteristic of the primary battery based on the fixed duty ratio, which comprises a lithium battery, a PWM circuit with the fixed duty ratio and a power output circuit;

the fixed duty ratio PWM circuit is electrically connected with the lithium battery and the power output circuit, and the power output circuit is also electrically connected with the lithium battery; the fixed duty ratio PWM circuit converts the output voltage of the lithium battery into the analog set primary battery voltage by outputting the set fixed duty ratio to the power output circuit.

Furthermore, the fixed duty ratio PWM circuit adopts a PWM generating circuit, and comprises a PWM circuit consisting of a 555 timer, a singlechip, a multivibrator and an operational amplifier or a comparator.

Further, the power output circuit is a voltage reduction circuit, a voltage boosting circuit or a voltage boosting and reducing circuit.

Further, the power output circuit adopts a DAC circuit.

Compared with the prior art, the invention has the following beneficial effects:

1. according to the invention, the voltage of the lithium battery is converted into the voltage of the simulation target primary battery in real time by setting the fixed duty ratio, the voltage is correspondingly reduced along with the reduction of the electric quantity, and the loss caused by sudden power failure is avoided.

2. The invention can provide a simpler and lower-cost circuit scheme, so that a lithium battery with larger capacity can be placed under the same volume, the cruising ability of a larger size is provided, and the cost is lower than that of the existing scheme under the condition of the same electric quantity.

3. The circuit of the invention only requires to output a signal with a fixed duty ratio due to complete open-loop control, so the control is extremely simple, even if a singlechip is used, the circuit can also be a minimum pin, for example, an SOT23-6 packaged singlechip, and the singlechip resource can also use the minimum resource, so the cost can also be extremely low.

Drawings

Fig. 1 is a schematic diagram of the principle of the embodiment of the present invention.

Fig. 2 is a circuit diagram 1 according to an embodiment of the invention.

Fig. 3 is a circuit diagram 2 according to an embodiment of the invention.

Detailed Description

The invention is further explained below with reference to the drawings and the embodiments.

It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

As shown in fig. 1, the present embodiment provides a voltage regulation method for simulating a discharge characteristic of a primary battery based on a fixed duty ratio, which specifically includes the following steps:

In this embodiment, the fixed duty cycle is calculated by the following formula:

In this example, the duty cycle is fixed at 35.7% ± 0.2% when a 1.5V output primary battery is simulated using a nominally 4.2V ternary lithium battery.

In this example, the duty cycle was fixed at 41.7% ± 0.2% when a 1.5V output primary cell was simulated using a nominal 3.6V lithium iron phosphate cell.

The embodiment also provides a voltage regulating circuit for simulating the discharge characteristic of the primary battery based on the fixed duty ratio, which comprises a lithium battery, a PWM circuit with the fixed duty ratio and a power output circuit;

In this embodiment, the fixed duty ratio PWM circuit may adopt a commercially available PWM generating circuit, including a PWM circuit composed of a 555 timer, a single chip, a multivibrator, an operational amplifier, or a comparator.

Further, when the fixed duty ratio PWM circuit is controlled by the single chip microcomputer, the single chip microcomputer is a low-power consumption single chip microcomputer, and after the single chip microcomputer starts PWM, other circuits are all in a dormant state.

The control of the circuit is extremely simple because of complete open-loop control, even if a singlechip is used, the circuit can also be a minimum pin, for example, an SOT23-6 packaged singlechip, and the singlechip resources can also use minimum resources, so the cost can also be extremely low.

In this embodiment, the power output circuit is a buck circuit, a boost circuit or a buck-boost circuit.

In this embodiment, the power output circuit may also be a buck switch circuit based on a triode or a MOS transistor, a DAC circuit, or the like.

The voltage variation corresponding to the fixed duty cycle output of this embodiment is as follows:

for a single 4.2V lithium battery, the corresponding output voltage is 1.5V, and the output ratio is fixed to 1.5/4.2 × 100% = 35.7%. When the battery voltage drops to 3.6V, the corresponding output is 3.6 × 35.7% = 1.2852V. Therefore, the voltage is continuously reduced along with the reduction of the electric quantity of the lithium battery, and the output voltage of the corresponding analog primary battery is correspondingly reduced according to the proportion, so that the risk of sudden power failure of equipment using the primary battery is avoided.

Because the internal resistance of the lithium battery is small, under the PWM working condition, the output impedance is equivalent to the internal resistance of the inductor plus the element, so that the voltage is still within the index range of the primary battery along with the fluctuation of the load, but the circuit is simple and easy to realize, and the cost can be the lowest of similar products.

The schematic block diagram of the power output circuit implemented by MOS transistors is shown in fig. 2. In fig. 2, the MOS transistor, the diode, the inductor, and the capacitor form a BUCK voltage reducing circuit. The diode of the power output circuit in fig. 2 can also adopt a MOS transistor, and the switching loss is reduced by synchronous rectification.

Further, in this embodiment, the fixed duty ratio PWM circuit may adopt a low power consumption MCU, as shown in fig. 3. In fig. 3, the U1 model is PIC10F320, and is used to generate a fixed PWM signal, control the on/off of the PMOS transistor Q1, and generate a voltage after voltage reduction with a fixed duty ratio after passing through L1 and C1. The output voltage Vp = Vbat D, the duty cycle D of a nominally ternary 4.2V ternary lithium battery is set to 35.7%, i.e., Vp =35.7% >. Vbat.

The present embodiment is an example of voltage reduction, and the same scheme can be used for voltage increase and voltage increase. On the basis of the fixed duty ratio, the power stage may adopt a boost circuit, a buck-boost circuit, etc., which belong to the well-known technology in the art and will not be described herein.

The foregoing is directed to preferred embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. However, any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention are within the protection scope of the technical solution of the present invention.

Claims

1. A voltage regulation method for simulating the discharge characteristic of a primary battery based on a fixed duty ratio is characterized by comprising the following steps:

2. The voltage regulation method for simulating the discharge characteristic of the primary battery based on the fixed duty ratio as claimed in claim 1, wherein the fixed duty ratio is calculated by the following formula:

3. The voltage regulation method for simulating the discharge characteristic of the primary battery based on the fixed duty ratio as claimed in claim 1, wherein when a nominal 4.2V ternary lithium battery is adopted to simulate a 1.5V output primary battery, the duty ratio is fixed to 35.7% ± 0.2%.

4. The voltage regulation method for simulating the discharge characteristic of a primary battery based on the fixed duty ratio as claimed in claim 1, wherein when a 1.5V output primary battery is simulated by using a nominal 3.6V lithium iron phosphate battery, the duty ratio is fixed to be 41.7% ± 0.2%.

5. A voltage regulating circuit for simulating the discharge characteristic of a primary battery based on a fixed duty ratio comprises a lithium battery, and is characterized by comprising a fixed duty ratio PWM circuit and a power output circuit;

6. The fixed duty cycle-based voltage regulation circuit for simulating the discharge characteristic of a primary battery according to claim 5, wherein the fixed duty cycle PWM circuit adopts a PWM generating circuit, and comprises a PWM circuit consisting of a 555 timer, a single chip microcomputer, a multivibrator, an operational amplifier or a comparator.

7. The fixed-duty-cycle-based voltage regulation circuit for simulating the discharge characteristic of a primary battery according to claim 5, wherein the power output circuit is a buck circuit, a boost circuit or a buck-boost circuit.

8. The fixed duty cycle based voltage regulation circuit for simulating the discharge characteristic of a primary battery of claim 5, wherein the power output circuit employs a DAC circuit.