JPH0595636A - Current resonance type step-down converter system charger - Google Patents

Abstract

PURPOSE:To materialize a light charger and use it for mounting on a car by stopping the operation of a switching regulator when the terminal voltage of a storage battery is low and does not reach the specified value, and when a specified time passes after it has reached the specified value by a charge stoppage circuit. CONSTITUTION:A charge stop circuit 3 outputs a signal 6', and a photocoupler 8 converts it into stoppage signals 7' and 8' so as to stop the operation of the exciting circuit of a rectifying circuit 9, whereby the charge is stopped. That is, when the voltage VB of a storage battery does not reach, for example, 16V, the circuit of an IC 5 detects this, and outputs a signal 6' through a diode D2. When a charge timer 6 receives the signal 4' being output after passage of, for example, three hours after operation of a battery voltage detection circuit 5, it outputs a signal 6' through a diode D3. When a key-on detection circuit 7 receives the signal 5' of the detection of the ON of a key switch, it outputs a signal 6' through a diode D5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a storage battery (battery) charger, which is particularly lightweight and suitable for use in vehicles.
The present invention relates to a current resonance type step-down converter system charger.

An electric vehicle is equipped with a storage battery and runs by supplying electric power to a motor. On the other hand, since the energy stored in the storage battery is limited, it is necessary to charge the storage battery from a commercial power source at any time using a charger.

However, if the charger is of a stationary type, the electric vehicle must move to the place where the charger is installed each time it is needed, which is inconvenient and imposes restrictions on the travelable distance. Become.

Therefore, if the charger itself can be mounted on an electric vehicle, it is very convenient because it can be charged from a household outlet, for example, but since the charger is generally heavy, it should be mounted on a vehicle. Is inappropriate.

Therefore, it is required to reduce the weight of the charger so that it can be mounted on an electric vehicle and used.

[0006]

2. Description of the Related Art Conventional chargers generally use a commercial power source of 5
Use a power transformer that operates at 0 [Hz] or 60 [Hz] to drop the voltage, rectify the low voltage on the secondary side with a diode, and then connect the storage battery directly without the smoothing circuit. , Is designed to be charged.

In this case, it is necessary to prevent an overcurrent when charging a deeply discharged storage battery. For this purpose, the power transformer is a leakage transformer to limit the current.

[0008]

As described above, in the conventional charger, since the step-down is performed by using the power transformer operated by the commercial power source, the weight becomes large and it is not possible to use it for the vehicle. It was suitable.

Further, in this case, since the charging current becomes a pulsating current (pulse current), there is a problem that noise (electromagnetic noise) having an audible frequency is generated. Also, because the charging current value fluctuates,
It is difficult to emphasize the protection fuse.

Further, there is a problem that the charging performance changes due to the fluctuation of the power supply voltage and the fluctuation of the power supply frequency.
Even when a leakage transformer is used as a power transformer, when a fully discharged storage battery is charged, an overcurrent is likely to occur and it is difficult to determine the capacity of the protective fuse.

In order to prevent overcurrent, there is also a system in which a part of the rectifying diode bridge is replaced with an SCR to limit the current. Even in such a case, however, the overcurrent is not enough for a fully discharged storage battery. Is difficult to control.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art by using a current resonance type step-down DC-DC converter which operates at a high frequency in a rectifier circuit and which has reduced weight. The purpose is to realize the device and make it usable for in-vehicle use.

[0013]

As shown in FIG. 1, a step-down converter type charger of the present invention is provided with respect to a rectifier circuit 9 having a current resonance type step-down high frequency switching regulator having constant voltage / constant current characteristics. The battery voltage detection circuit 5 is provided to generate a detection signal when the terminal voltage V _{B of the} storage battery B charged by the rectifier circuit 9 exceeds a predetermined value, and the charging timer 6 is provided to detect the battery voltage detection circuit 5. The charging stop circuit 3 generates an output by counting a predetermined time from the detection signal generation.
The provided, when the terminal voltage V _B of the battery B is less than or equal to another predetermined value, and when the output generation of the charging timer 6 generates an output to stop the operation of the switching regulator, is provided an abnormality detection timer 4, the charge Generates a signal that suppresses the operation of the charge stop circuit 3 for another predetermined time from the start, and
A backflow preventing diode D7 is connected between the output terminal of the rectifying circuit 9 and the storage battery B.

[0014]

The rectifier circuit according to the present invention is provided with a current resonance type step-down high frequency switching regulator,
Has constant current characteristics. Further contrast, the charging stop circuit, and when the terminal voltage V _B of the battery B does not reach the lower predetermined value, when the predetermined time has elapsed after reaching another predetermined value battery voltage rises, the switching regulator The rectification circuit and the storage battery are protected by stopping the operation of and stopping the charging.

Further, for another predetermined time from the start of charging, the operation of the charge stop circuit is suppressed to perform the forced charging, and when the storage battery voltage does not reach the predetermined value during that period, the charging is stopped so that the storage battery becomes abnormal. If, protect the rectifier circuit.

Further, by connecting a diode for preventing backflow between the output side of the rectifier circuit and the storage battery, the output impedance of the rectifier circuit is low.
Prevents backflow of current from the storage battery to the rectifier circuit.

[0017]

1 shows an embodiment of the present invention, in which a rectifier circuit 9 for generating a charging voltage for a storage battery B from a commercial power supply AC100V or 200V is mainly arranged, and a constant voltage circuit 1, The lamp display circuit 2, the charging stop circuit 3, the abnormality detection timer 4, the battery voltage detection circuit 5, the charging timer 6, the key-on detection circuit 7, and the photocoupler 8 are provided. Hereinafter, each unit will be described in more detail.

FIG. 2 shows an example of the structure of the rectifier circuit. The rectifier circuit 9 is composed of a high frequency switching regulator circuit that constitutes a current resonance type step-down converter. The DC voltage obtained by rectifying the commercial power input AC100V or 200V by the rectifier D8 and smoothing it by the capacitor C7 is supplied to the switching transistor Q1 via the primary side of the transformer T1.

Then, by controlling the on / off of the switching transistor Q1 by the excitation circuit EX, a high-frequency (about 1 MHz) intermittent current flows through the primary side of the transformer T1. The high frequency low voltage generated on the secondary side of the transformer T1 by this is rectified by the diodes D9 and D10, and current-resonated in the resonance circuit composed of the capacitor C8 and the choke L1.
It operates as a C-DC converter.

At this time, the output current value is detected by the series resistor R25, the output voltage value is detected by the voltage dividing resistors R26 and R27, and the error signal obtained by comparison with the reference voltage is sent to the photocouplers PC1 and PC2. After that, by being fed back to the excitation circuit EX, a stabilized DC output voltage is generated.

FIG. 3 shows the output characteristics of the switching regulator circuit, which has constant voltage and constant current characteristics. In FIG. 3, it is shown to have a constant voltage output with an output voltage of 30.5 V and a constant current output of 8.6 A.

The DC output voltage is the backflow prevention diode D.
It is supplied to the storage battery B via 7 and is charged. The voltage V _{B of the} storage battery B is supplied to each control circuit,
It is connected to the lamp display circuit 2 via the indicator lamp PL, and is connected to the key-on detection circuit 7 via the switch S which is turned on in association with turning off the key switch.

Further, the auxiliary power output is generated by stepping down the commercial power input by the transformer T2 and rectifying it via the rectifier D6. Auxiliary power output is constant voltage circuit 1
After that, it is supplied to each control circuit as a constant voltage output V _CC of DC 15V, for example.

Returning to FIG. 1, in the lamp display circuit 2, the indicator lamp PL is turned on and displayed when the charging current is flowing in accordance with the signal in which the charging current of the storage battery B is detected by the shunt resistor RS. Further, when the charging timer 6 has started to operate, the internal oscillation circuit is operated by the signal indicated by, thereby causing the indicator lamp PL to blink and display.

FIG. 4 shows a configuration example of the charge stop circuit. The charge stop circuit 3 outputs a signal of under the following conditions, and the photo coupler 8 converts the signal into a stop signal indicated by, and the excitation circuit EX in the rectifier circuit 9 outputs.
Charging is stopped by stopping the operation of.

(1) When the storage battery voltage V _B does not reach, for example, 16 V, the circuit of the IC 5 detects it and outputs a signal via the diode D2. (2) When the charge timer 6 receives a signal output, for example, 3 hours after the operation of the battery voltage detection circuit 5, the diode D
The signal is output via 3. (3) In the key-on detection circuit 7, when a signal generated by the operation of the switch S that detects the ON state of the key switch is received, the diode D5
To output a signal.

FIG. 5 shows a configuration example of the abnormality detection timer. The abnormality detection timer 4 generates a signal from the comparator IC4 for, for example, 3 minutes determined by the capacitor C4 and the resistor R14 after the power is turned on,
The output of the signal in the charge stop circuit 3 is suppressed to enable forced charging for 3 minutes. If the voltage does not rise due to the abnormality of the battery B even after the forced charging for 3 minutes, the charging stop circuit 3 operates to stop the charging after the elapse of this time.

FIG. 6 shows a configuration example of the battery voltage detection circuit. The battery voltage detection circuit 5 activates the charging timer 6 by generating a signal from the comparator IC3 when the charged amount reaches a storage battery voltage V _B 28.8 V corresponding to 80%, for example. It is given to the lamp display circuit 2 to blink the indicator lamp PL.

FIG. 7 shows an example of the configuration of the charge timer. The charging timer 6 has an internal timer circuit I
It has C1 and counts, for example, 3 hours from the time when a signal is generated from the battery voltage detection circuit 5 due to a rise in the storage battery voltage accompanying charging, and when that time has elapsed, outputs a signal and operates the charging stop circuit 3. By this, the charging is stopped.

FIG. 8 shows an example of the structure of the photocoupler. When a signal is generated from the charge stop circuit 3, the photocoupler 8 generates a stop signal that is insulated from the signal, and stops the operation of the excitation circuit EX in the rectifier circuit 9. As a result, the DC voltage output of the rectifier circuit 9 is stopped and charging is stopped.

Since the output impedance of the current resonance type DC / DC converter is relatively low when the charging is stopped, the diode D7 is inserted in series with the output of the storage battery to prevent the reverse flow of the storage battery current.

The switch S works in conjunction with the key switch,
It turns off when the key switch is on, and turns on when the key switch is off. As a result, the key-on detection circuit 7 generates a signal when the key switch is turned on, and the charge stop circuit 3
Is operated to stop charging in the rectifier circuit 9.

This is because if charging is performed with the key switch turned on, if the accelerator is mistakenly operated during charging, the electric vehicle will start moving with the power cord still connected, so the key switch must be turned off. This is to prevent charging.

FIG. 9 shows an operation timing chart of the charger of the present invention. Now, when charging is started at time t ₀ , the charging timer 6 is initially in the off state.
When the voltage V is 16 V or more when 3 minutes have passed from the time t _{0, the} charging proceeds and the charging is continued at the constant current I = 8.6A.

When the voltage V reaches 28.8 V, the charging timer 6 is started based on the signal from the battery voltage detection circuit 5. The storage battery voltage V rises, and at time t ₂ , 30.
At 5V, the voltage V becomes constant thereafter, but the charging current I
Gradually decreases and becomes constant at 3 A, for example. When the charge timer 6 ends after 3 hours, the rectifier circuit 9 stops operating due to the operation of the charge stop circuit 3, and both the voltage V and the current I become 0 and the charging ends.

Therefore, in the operation of the switching regulator in the rectifier circuit 9, the current I is constant at 8.6 A until the voltage V rises from 0 to 30.5 V, but the voltage reaches 30.5 V. When it reaches, the current I gradually decreases and settles in the state of I = 3A. Therefore, electrolysis of water in the battery can be minimized. Three
After a lapse of time, the current V and the voltage I become 0 by the operation of the charging timer 6, and the charging is completed.

[0037]

As described above, according to the present invention,
In the rectifier circuit, the power supply voltage is directly rectified to operate the switching regulator, and since the high frequency switching regulator is used, the weight of the switching transformer, the rectifying choke, and the capacitor can be reduced. It can be set to 1/5. Therefore, according to the present invention, a small and ultra-lightweight step-down converter system charger can be configured.

Further, since the charger of the present invention has a high switching frequency in the switching regulator of the rectifying circuit, it is possible to prevent low frequency noise from being generated from the transformer or the like.

Further, since the current resonance type step-down converter system charger of the present invention has the constant voltage characteristic, the output characteristic does not fluctuate with respect to the fluctuation of the power supply voltage, and the constant current characteristic allows the perfect discharge. Even in the case of the storage battery of No. 3, overcurrent does not flow, and it is easy to coordinate the power supply and the protection fuse in each unit, and the selection thereof is easy.

The current resonance type step-down converter system charger of the present invention is particularly suitable as a vehicle-mounted charger for an electric vehicle or the like, but is not limited to this, and can be used as a general-purpose stationary charger. It is possible.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an exemplary embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration example of a rectifier circuit.

FIG. 3 is a diagram showing output characteristics of a switching regulator circuit.

FIG. 4 is a diagram showing a configuration example of a charge stop circuit.

FIG. 5 is a diagram showing a configuration example of an abnormality detection timer.

FIG. 6 is a diagram showing a configuration example of a battery voltage detection circuit.

FIG. 7 is a diagram showing a configuration example of a charging timer.

FIG. 8 is a diagram showing a configuration example of a photocoupler.

FIG. 9 is a diagram showing an operation timing chart of the charger of the present invention.

[Explanation of symbols]

3 Charge stop circuit 4 Abnormality detection timer 5 Battery voltage detection circuit 6 Charge timer 9 Rectifier circuit B Battery V _B terminal voltage D7 Diode

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[Procedure amendment]

[Submission date] November 10, 1992

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 4

[Correction method] Change

[Correction content]

[Figure 4]

Claims (1)

[Claims] 1. A storage battery (B) which is charged by a rectifier circuit having a current resonance type step-down high frequency switching regulator having constant voltage / constant current characteristics.
A battery voltage detection circuit that generates a detection signal when the terminal voltage (V _B ) of the battery voltage exceeds a predetermined value, a charging timer that counts a predetermined time from the detection signal generation of the battery voltage detection circuit and generates an output, when battery terminal voltage (V _B) is different than a predetermined value (B), and when the output generation of the charging timer,
A charge stop circuit that generates an output that stops the operation of the switching regulator and another predetermined time from the start of charging,
An abnormality detection timer for generating a signal for suppressing the operation of the charge stop circuit is provided, and a diode (D) for preventing backflow is provided between the output terminal of the rectifier circuit and the storage battery (B).
A current resonance type step-down converter system charger characterized in that 7) is connected.