JP2005033951A - Power supply device equipped with protection circuit of battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce erroneous operation caused by noise by using an inexpensive electronic part low in withstand voltage. <P>SOLUTION: This power supply device comprises secondary batteries 1 connected in series to one another, a battery state detection circuit 2 outputting a state signal that indicates a normal state or an abnormal state by detecting the state of each secondary battery 1, a level shift circuit 3 that level-shifts the output signal of the battery state detection circuit 2, and an operation circuit 4 that operates the level-shifted output signal. The level shift circuit 3 converts the output signal of the battery state detection circuit 2 to the magnitude of a current and transmits it. The operation circuit 4 logically operates the signal transmitted from the level shift circuit 3 and the output signal of the battery state detection circuit 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a power supply device in which a plurality of secondary batteries are connected in series, and to a power supply device including a protection circuit that detects the state of each secondary battery. In particular, the present invention relates to a power supply device including a protection circuit that detects a state of each secondary battery by connecting a large number of secondary batteries in series.

  It is important to use a power supply device including a plurality of secondary batteries while charging and discharging while detecting overcharge and overdischarge of the battery to protect the battery. This is because overcharge and overdischarge significantly deteriorate the battery. This power supply apparatus includes a type including a protection circuit that manages a plurality of batteries in total and a protection circuit that manages the state of each battery independently. The battery management type can simplify the protection circuit. However, all the batteries are not overcharged or overdischarged in the same way, and batteries with a reduced charge capacity are easily overcharged and overdischarged. If it will be in this state, the battery in which charge capacity decreased will be overcharged or overdischarged, and battery performance will fall rapidly. For this reason, when any battery deteriorates and performance falls, there exists a fault that the performance of this battery deteriorates rapidly.

  A power supply device including a protection circuit that independently detects the state of all batteries can charge and discharge so as to prevent overcharging and overdischarging of the battery even if the charging capacity of any battery is small. For this reason, overcharging and overdischarging of all the batteries can be prevented, safety can be improved, and battery life can be significantly prolonged.

  However, the power supply device including this protection circuit has a complicated circuit configuration of the protection circuit. In particular, a protection circuit that connects a large number of secondary batteries in series and independently detects overcharge and overdischarge of all the batteries increases the cost of the electronic components used. This is because a large number of batteries are connected in series to increase the power supply voltage, so that an electronic component that can withstand this power supply voltage, that is, a high voltage is used. In particular, power supply devices for applications requiring high output, such as power bicycles, electric vehicles, power tools, etc., need to increase the output voltage by connecting a number of secondary batteries in series. In addition, it is necessary to use an element that can withstand a high voltage for the electronic components used in the protection circuit, which increases the cost.

In order to solve this drawback, the voltage of each battery is detected by a voltage detection circuit and the output signal detected by each voltage detection circuit is level-shifted and calculated, or the output of each voltage detection circuit is a photocoupler. A circuit has been developed that provides insulation and output. (See Patent Document 1)
Japanese Patent Laid-Open No. 2003-111297

  Since the circuit described in this publication is detected by a voltage detection circuit that uses the negative side of each battery as the ground potential, the withstand voltage of the electronic components used in the voltage detection circuit is one battery voltage. For this reason, it is not necessary to use an expensive transistor or FET that can withstand a high voltage in the voltage detection circuit. Also, since the output of each voltage detection circuit is transmitted to the voltage determination means or insulated and output by a photocoupler, a transistor or FET that withstands a high voltage is also used in the circuit that processes the output signal of the voltage detection circuit. It is not necessary and can be manufactured with inexpensive elements.

  However, such a circuit is easily affected by noise in a device that requires a high output or a motor-driven device. Therefore, it is particularly important how much the influence of the noise can be reduced on the battery protection circuit. .

  The present invention has been developed for the purpose of realizing this, and an important object of the present invention is that an inexpensive electronic component having a low withstand voltage can be used as an electronic component to be used. It is an object of the present invention to provide a power supply device including a battery protection circuit that can be significantly reduced.

  The power supply device of the present invention includes a secondary battery 1 connected in series with each other, and a normal or abnormal condition of the secondary battery 1 by detecting the state of each secondary battery 1 connected to each secondary battery 1. A battery state detection circuit 2 that outputs a state signal indicating a level, a level shift circuit 3 that level-shifts the output signal of the battery state detection circuit 2, and an arithmetic circuit 4 that calculates an output signal level-shifted by the level shift circuit 3; Is provided. The level shift circuit 3 converts the output signal of the battery state detection circuit 2 into a current magnitude and transmits it.

  The power supply device of the present invention can connect two or more lithium ion batteries in series. The battery state detection circuit 2 can include either an overcharge detection circuit that detects overcharge of the secondary battery 1 or an overdischarge detection circuit that detects overdischarge of the secondary battery 1. The arithmetic circuit 4 includes a logic circuit such as an OR circuit and an AND circuit, and a signal level-shifted by the level shift circuit 3 and a signal not level-shifted can be input to the logic circuit. Furthermore, the power supply device of the present invention can transmit the calculation results of the calculation circuit 4 to other calculation circuits 4 one after another. Furthermore, the power supply device can detect a connection abnormality or a battery abnormality based on two or more signal transmission results.

  In the power supply device of the present invention, an inexpensive electronic component with a low withstand voltage can be used. The battery state detection circuit is connected to each battery, the state of each battery is detected by each battery state detection circuit, the detected signal is level-shifted by a level shift circuit, and processed by an arithmetic circuit. Because. Furthermore, the power supply device of the present invention has a feature that malfunctions due to noise can be remarkably reduced. This is because the level shift circuit has a configuration in which the input signal is converted into current and transmitted. This is particularly important for a power supply device in which a large number of secondary batteries are connected in series to increase the output voltage. This is because pulsed noise occurs when the power supply device with a high output voltage is switched, such as in an electric bicycle, electric tool, electric vehicle, etc., where the motor requires a high output. It is because it is suitable for the use to do. This is because in applications where noise is likely to be generated, normal operation cannot be performed unless the malfunction caused by noise is reduced.

  Embodiments of the present invention will be described below with reference to the drawings. However, the embodiments described below exemplify a power supply device for embodying the technical idea of the present invention, and the present invention does not specify the power supply device as follows.

  Further, in this specification, in order to facilitate understanding of the claims, numbers corresponding to the members shown in the examples are indicated in the “claims” and “means for solving the problems” columns. It is appended to the members shown. However, the members shown in the claims are not limited to the members in the embodiments.

  The power supply device shown in the circuit diagrams of FIG. 1 to FIG. 4 shows a secondary battery 1 connected in series with each other, and is connected to each battery to detect the state of each battery to indicate normality or abnormality of the battery. A battery state detection circuit 2 for outputting a state signal; a level shift circuit 3 for level shifting the output signal of the battery state detection circuit 2; and an arithmetic circuit 4 for calculating an output signal level-shifted by the level shift circuit 3. .

  The secondary battery 1 is a lithium ion battery. However, any secondary battery such as a nickel-hydrogen battery or a nickel-cadmium battery can be used as the battery. The power supply device shown in the figure has three secondary batteries 1 connected in series. However, the power supply device of the present invention can be applied to a device in which two or more secondary batteries are connected in series.

  The battery state detection circuit 2 detects overcharge and overdischarge of each battery. Since this battery state detection circuit 2 detects overcharge or overdischarge of the connected battery, the ground potential is set to the negative side of the battery. For this reason, each battery state detection circuit 2 will be in the state mutually connected in series, and earth potentials differ. Since the battery state detection circuit 2 detects the voltage of one battery and the like, the electronic components such as transistors and FETs used in this circuit are voltages that can withstand one battery voltage, and therefore use a high withstand voltage. There is no need.

  The battery state detection circuit 2 detects a battery voltage to detect overcharge or overdischarge, or loads a charge current or discharge current flowing through the battery to detect overcharge or overdischarge, or both voltage and current. Detects overcharge and overdischarge. The battery state detection circuit 2 outputs a normal signal when the charged battery can be charged, and outputs an abnormal signal when the battery is fully charged and overcharged. Also, a normal signal is output when the discharged battery can be discharged, and an abnormal signal is output when the battery is overdischarged.

  The battery state detection circuit 2 detects the battery temperature with a temperature sensor (not shown). The battery state detection circuit 2 outputs a normal signal in a temperature range in which the battery can be normally charged / discharged, that is, in a state where the battery temperature is lower than the set temperature, and the battery temperature becomes higher than the set temperature, An abnormal signal is output when charging / discharging of the battery is stopped.

  The battery state detection circuit 2 outputs a normal signal as “High” and an abnormal signal as “Low”, or outputs a normal signal as “Low” and an abnormal signal as “High”.

  The battery state detection circuit 2 described above detects the state of the battery using the battery voltage, the current flowing through the battery, and the battery temperature as parameters. However, the power supply device of the present invention does not specify a parameter for the battery state detection circuit 2 to detect the state of the battery. Further, the state detected from the detected parameters is not specified as overcharge, overdischarge, temperature, or the like. The battery state detection circuit 2 detects various states so as not to deteriorate the electrical performance of the power supply, or detects a state where the battery can be charged / discharged safely, and outputs the detected signal by switching from the normal signal to the abnormal signal. To do.

  Since each of the battery state detection circuits 2 is out of ground potential, the level shift circuit 3 level-shifts the output signal and inputs it to the arithmetic circuit 4. The level shift circuit 3 for level shifting the output signal of the battery state detection circuit 2 includes a series circuit of a switching element 5 and a constant current circuit 6 that are switched on and off by the battery state detection circuit 2. The series circuit is connected to both ends of the batteries that are adjacently connected in series. The level shift circuit 3 switches the switching element 5 on and off by the battery state detection circuit 2 and outputs a level-shifted signal from an intermediate connection point 7 between the constant current circuit 6 and the switching element 5. The level-shifted output signal is input to the arithmetic circuit 4.

  The level shift circuit 3 of FIGS. 1 and 2 performs level shift so as to raise the ground potential of the output signal output from the battery state detection circuit 2 connected to the lower stage in the figure, and this level shifted signal The output signal of the upper battery state detection circuit 2 is input to the arithmetic circuit 4. In the level shift circuit 3, the constant current circuit 6 is connected to the upper stage, that is, the positive side of the battery, and the switching element 5 is connected to the negative side of the battery.

  The level shift circuit 3 in FIG. 3 and FIG. 4 performs level shift so as to lower the ground potential of the output signal output from the battery state detection circuit 2 connected to the upper stage in the figure, and this level shifted signal The output signal of the lower battery state detection circuit 2 is input to the arithmetic circuit 4. In the level shift circuit 3, the constant current circuit 6 is connected to the lower stage, that is, the negative side of the battery, and the switching element 5 is connected to the positive side of the battery.

  The arithmetic circuit 4 shown in FIGS. 1 and 3 includes an OR circuit. The battery state detection circuit 2 shown in these drawings sets the normal signal to “Low” and the abnormal signal to “High”. For example, the battery state detection circuit 2 outputs “Low” as a normal signal until the charged battery is fully charged, and outputs “High” as an abnormal signal to be fully charged. The switching element 5 of the level shift circuit 3 is switched on by “High” output from the battery state detection circuit 2. The switching element 5 is in an off state when “Low” is output from the battery state detection circuit 2.

  In FIG. 1, when the battery at the lowermost stage is fully charged and the output signal of the battery state detection circuit 2 at the lowermost stage is switched from “Low” of the normal signal to “High” of the abnormal signal, the “High” signal is The switching element 5 is switched from off to on. The level shift circuit 3 switched to this state inputs the level-shifted “High” to the lower OR circuit which is the arithmetic circuit 4. The OR circuit switches the output from “Low” to “High” when “High” is input to one side. The “High” signal output from the lower OR circuit switches the switching element 5 of the level shift circuit 3 connected to the upper stage from OFF to ON, and the upper OR circuit from the intermediate connection point 7 of the level shift circuit 3. To output a “High” signal. In the upper OR circuit, “High” is input to one input, and the output signal is set to “High”. In this way, “High” output from the lowermost battery state detection circuit 2 is level-shifted and output as an “High” signal of an abnormal signal from the uppermost OR circuit. That is, when any one of the batteries is fully charged and “High” that is an abnormal signal is output, the level is shifted and the final output is set to “High”. When “High” is output as the final signal, it is determined that one of the batteries is fully charged and charging needs to be stopped, and charging is stopped.

  The above shows the state where the bottom battery is fully charged, but when the second battery from the bottom is fully charged, the output signal of the intermediate battery state detection circuit 2 changes from “Low” to “High”. Then, this “High” sets the output of the lower OR circuit to “High”, and thereafter operates in the same manner as when the lowermost battery is fully charged, and the final output signal becomes “High”. When the uppermost battery is fully charged and the output signal becomes “High”, this “High” is input to the uppermost OR circuit, and the output of the uppermost OR circuit is set to “High”.

  The arithmetic circuit 4 shown in FIGS. 2 and 4 includes an AND circuit. The battery state detection circuit 2 shown in these figures sets the normal signal to “High” and the abnormal signal to “Low”. For example, the battery state detection circuit 2 outputs “High” as a normal signal until the discharged battery is completely discharged, and outputs “Low” as an abnormal signal when the battery is completely discharged. The switching element 5 of the level shift circuit 3 is switched on by “High” output from the battery state detection circuit 2. The switching element 5 is in an off state when “Low” is output from the battery state detection circuit 2.

  In FIG. 2, when the battery at the lowermost stage is completely discharged and the output signal of the battery state detection circuit 2 at the lowermost stage is switched from “High” of the normal signal to “Low” of the abnormal signal, the switching element 5 Switch from on to off. The level shift circuit 3 switched to this state inputs the level shifted “Low” to the lower AND circuit which is the arithmetic circuit 4. When “Low” is input to one of the AND circuits, the output is switched from “High” to “Low”. The “Low” signal outputted from the lower AND circuit switches the switching element 5 of the level shift circuit 3 connected to the upper stage from on to off, and the upper AND circuit from the intermediate connection point 7 of the level shift circuit 3. Output a “Low” signal. In the upper AND circuit, “Low” is input to one input and the output signal is set to “Low”. In this way, “Low” output from the lowermost battery state detection circuit 2 is level-shifted and output as an “Low” signal of an abnormal signal from the uppermost AND circuit. That is, when any one of the batteries is overdischarged and an abnormal signal “Low” is output, the level is shifted and the final output is set to “Low”. When “Low” is output as the final signal, it is determined that one of the batteries is overdischarged, and the discharge is stopped.

  The above shows the state in which the battery at the lowest stage is overdischarged. However, when the battery at the second stage from the bottom is overdischarged, the output signal of the intermediate battery state detection circuit 2 changes from “High” to “Low”. Then, this “Low” sets the output of the lower AND circuit to “Low”, and thereafter operates in the same manner as when the lowermost battery is overdischarged, and the final output signal becomes “Low”. When the uppermost battery is overdischarged and the output signal becomes “Low”, this “Low” is input to the uppermost AND circuit, and the output of the uppermost AND circuit is set to “Low”.

  In the level shift circuit example of the above embodiment, a signal is transmitted with and without current. However, by transmitting a signal with large and small current, it can be made more resistant to noise.

  Further, when an abnormal signal is detected at the same time in response to the transmission results of overcharge and overdischarge, it can be easily understood that a battery cell balance abnormality or disconnection from the battery has occurred.

1 is a circuit diagram of a power supply device according to an embodiment of the present invention. The circuit diagram of the power supply device concerning the other Example of this invention. The circuit diagram of the power supply device concerning the other Example of this invention. The circuit diagram of the power supply device concerning the other Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Secondary battery 2 ... Battery state detection circuit 3 ... Level shift circuit 4 ... Arithmetic circuit 5 ... Switching element 6 ... Constant current circuit 7 ... Intermediate connection point

Claims (6)

Secondary battery (1) connected in series with each other, and connected to each secondary battery (1) to detect the state of each secondary battery (1) The battery level detection circuit (2) that outputs a status signal indicating abnormality, the level shift circuit (3) that level shifts the output signal of the battery status detection circuit (2), and the level shift circuit (3) are level shifted. A power supply device comprising an arithmetic circuit (4) for calculating an output signal,
A power supply device comprising a battery protection circuit, wherein the level shift circuit (3) converts the output signal of the battery state detection circuit (2) into a current magnitude and transmits the signal.   A power supply device comprising the battery protection circuit according to claim 1, wherein two or more lithium ion batteries are connected in series.   The battery state detection circuit (2) comprises either an overcharge detection circuit for detecting overcharge of the secondary battery (1) or an overdischarge detection circuit for detecting overdischarge of the secondary battery (1). A power supply device comprising the battery protection circuit described in 1.   The battery protection circuit according to claim 1, wherein the arithmetic circuit (4) includes a logic circuit, and a signal level-shifted by the level shift circuit (3) and a signal not level-shifted are input to the logic circuit. A power supply device comprising:   The power supply device comprising the battery protection circuit according to claim 1, wherein the arithmetic circuit (4) transmits the calculation results to the other arithmetic circuits (4) one after another. 2. A power supply apparatus comprising a battery protection circuit according to claim 1, wherein a connection abnormality or a battery abnormality is detected based on two or more signal transmission results.

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