JPH05284666A - Battery temperature detecting system for cahrger - Google Patents

Abstract

PURPOSE:To provide a battery temperature detecting system for a charger in which battery temperature is detected easily and accurately at the time of quick charge in particular while eliminating adverse effect of noise, voltage drop, and the like caused by a current flowing through a common part of the battery and the circuitry of a temperature sensor. CONSTITUTION:The battery temperature detecting system comprises a charge control circuit 2 producing a charge current control command based on the battery temperature, and a switch Q2 controlling the charge current of a secondary charging circuit based on a control command fed from the charge control circuit 2. When the battery temperature is detected, the switch Q2 opens the secondary charging circuit based on the control command fed from the charge control circuit 2 to bring the charge current to zero, and the charge control circuit 2 reads out the resistance or voltage of a thermister 4 for detecting the temperature of the battery 3. Since the charging current flowing on the secondary is brought to zero based on a control command fed from the charge control circuit 2, adverse effect of noise, voltage drop, and the like caused by a current flowing through a common part between the battery 3 and a temperature sensor, i.e., the thermister 4, is eliminated resulting in a correct temperature detection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery temperature detecting method for a battery charger which charges a battery with a charge current of 1C or more, and more particularly to a battery temperature detecting method for a battery charger which detects the battery temperature in a battery open state. ..

[0002]

2. Description of the Related Art An example of the prior art will be described with reference to FIG. In the figure, T1 is a transformer, 6 is a DC voltage generating circuit, Q1 is a switch composed of elements such as FETs for switching the primary side voltage of the transformer T1, D1,
D2 is a rectifier diode on the secondary side of the transformer T1, C1 is a smoothing capacitor, and CH is a choke. Reference numeral 5 denotes a battery pack, in which the battery 3 and the thermistor 4 are housed. Thermistor 4 is battery 3
Is a temperature sensor for detecting temperature, and detects temperature by a change in resistance value or a voltage change due to temperature change. 1
Is a PWM control IC for PWM controlling the switch Q1. Reference numeral 2 is a charge control circuit composed of a 4-bit CPU or the like, and detects the temperature and voltage of the battery 3.

It is necessary to protect the battery 3 by monitoring the temperature of the battery 3 at the time of charging and controlling the flow of charge depending on the temperature of the battery 3 to prevent overcharging or stop charging when the temperature is abnormal. is there. In the quick charger, the temperature of the battery 3 is changed to the battery pack 5
The temperature may be detected by the temperature detecting thermistor 4 placed inside. The resistance value of the thermistor 4 or the voltage-converted data by the resistance is used as C of the charge control circuit 2.
It is processed by PU or the like to control charging.

The DC voltage on the primary side is pulsed by the switch Q1 at the frequency and pulse width set by the PWM control IC1 and transmitted to the secondary side via the transformer T1. On the secondary side, this waveform is rectified by diode R
1, D2, choke CH, smoothing capacitor C1 is used to charge the battery 3 with a charging current that is made into a direct current. When detecting the temperature of the battery 3, the charge control circuit 2 reads the information from the thermistor 4 via the terminal T based on the command from the charge control circuit 2.

[0005]

However, in the battery temperature detecting method of the charger in the conventional example, the negative terminal of the battery and the negative terminal of the thermistor are common. Due to the influence of the impedance of the common portion and the like, in a charger that charges with a charging current of 1 C or more, the temperature detected by the thermistor is easily affected by noise, voltage drop, etc. in the circuit input to the charge control circuit. There are challenges.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a battery temperature detection system for a charger which can accurately and easily detect the temperature of the battery.

[0007]

In order to solve the above-mentioned problems, the battery temperature detecting method for a charger according to the present invention is a battery for a charger which detects a battery temperature by charging the battery with a charging current of 1C or more. In the temperature detection method, a charging control circuit that issues a control command for the charge-diffusion based on the battery temperature, and a switch that controls the charge-diffusion of the secondary-side charging circuit based on the control command of the charge control circuit are provided. , When detecting the battery temperature,
The switch is characterized in that the charging circuit on the secondary side is opened so that the charging flow is zero based on a control command from the charging control circuit.

[0008]

In the battery temperature detecting method for the charger according to the present invention, the semiconductor switch is used to control the charge flow that flows in the charging circuit, and the charge flow that flows to the secondary side is made zero by the control command of the charge control circuit. .. That is, the charge control circuit reads the battery voltage and the resistance value of the thermistor or the converted voltage of the thermistor while the semiconductor switch is OFF.
Normally, when the charging flow is flowing, this loop is affected by noise and voltage drop, but if you read the resistance value only when this loop is cut off, current does not flow, so it is accurate. You can measure.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In the figure, the elements denoted by the same reference numerals as those in FIG. 2 indicate the same elements, and the description thereof will be omitted. First, Q2 is a switch, which is a semiconductor transistor in the example. When the temperature of the battery 3 is detected, the switch Q2 cuts off the charge flow to the battery 3 based on the command from the charge control circuit 2. In the charge control circuit 2, the switch Q2 is turned on in the same manner as the temperature rises in synchronization with the voltage of the battery 3.
Go to read in the state of FF. As described above, in a charger that charges at 1C or more, it is preferable to measure the information on the battery voltage with the charging circuit as an open circuit in order to control charging. In this case, the battery voltage is detected even when the temperature of the battery is detected. By performing the measurement in synchronization with, it is possible to detect without being affected by external factors. These are CPs that make up the charge control circuit 2.
It is controlled by U etc.

[0010]

As described above, according to the battery temperature detecting method of the charger of the present invention, the charging control circuit that issues the control command of the charge flow and the control command of the charging control circuit based on the battery temperature. And a switch for controlling the charging flow of the secondary side charging circuit, and when detecting the battery temperature, the switch opens the secondary side charging circuit based on a control command of the charging control circuit. As the charging flow is set to zero,
The battery temperature can be detected accurately and easily. That is, it is possible to eliminate the influence of noise or a voltage drop when the charging flow is flowing, and to easily and accurately detect the battery temperature as well as the battery voltage.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a battery temperature detection system of a charger according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of a battery temperature detection system of a charger in a conventional example.

[Explanation of symbols]

 C1 Smoothing capacitor CH Choke D1, D2 Rectifier diode Q1, Q2 Switch T1 Transformer 1 PWM control IC 2 Charge control circuit 3 Battery 4 Thermistor 5 Battery pack 6 DC voltage generation circuit

Claims (1)

[Claims] 1. In a battery temperature detection system of a charger for charging a battery with a charging current of 1C or more and detecting the battery temperature, a charging control circuit for issuing a control command of the charging current based on the battery temperature, A switch for controlling the charging flow of the secondary side charging circuit based on the control command of the charging control circuit, and the switch based on the control command of the charging control circuit when detecting the battery temperature. A battery temperature detection method for a charger characterized in that the charging circuit on the secondary side is an open circuit so that the charging flow is zero.