JPH01186134A - Charger for vehicle - Google Patents

Abstract

PURPOSE:To prevent a battery from quickly discharging by providing a circuit for detecting the discharging state of the battery, a booster for raising a battery voltage to a predetermined voltage to apply it to a rotor coil, and a control circuit for operating the booster when the battery discharge is detected. CONSTITUTION:A discharging state detector 108 detects the collector voltage of a transistor 101 to know its operation duty, and generates a '1' level output when the duty becomes 100%. A control circuit 110 inputs one phase voltage of a stator coil 22 to know its generation start, and receives the generation start and '1' level output of a discharging state detector 109 to operates a DC/DC converter 111 due to boosting means of rear stage. The converter 111 raises the output voltage of a charging generator 2 to a predetermined voltage, and applies it to a rotor coil 21 through a diode 112.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a vehicle charging device, and particularly to a vehicle charging device that is capable of suppressing the amount of battery discharge to a small level even when a large electrical load is used, such as when the vehicle is idling. Regarding a charging device.

[Prior Art] FIG. 2 shows a change in a charging generator output current according to the rotational speed of a rotating generator (rotor coil) connected to an engine with the rotor coil in a fully excited state.

As is known from Figure 2, the output current of the generator rapidly decreases as its rotational speed decreases, and when the maximum current value of the onboard electrical load is shown by the broken line in the figure, it In the range, the output current of the charging generator becomes smaller than the load current.

Therefore, in this case, constant voltage control by the regulator is impossible, and the battery voltage is closer to the battery's rated voltage (e.g. 12V) than the normal regulation voltage (e.g. 14.5V).
V).

[Problems to be Solved by the Invention] Normally, the excitation voltage of the rotor coil is supplied from a battery, so a decrease in battery voltage causes a decrease in the rotor coil excitation current, reducing the generator output current, and reducing the battery voltage. This promotes discharge and causes what is called a dead battery.

Therefore, in order to solve this problem, the present invention provides a vehicle charging device that can suppress the amount of battery discharge to a small level even when a large capacity load is used when the charging generator rotates at low speed, such as when the vehicle is idling. The purpose is to provide.

[Means for Solving the Problems] A vehicle charging device that excites the rotor coil 21 of the charging generator 2 with the battery voltage and charges the battery 3 with the generated voltage generated in the stator coil 22 has the following features: a booster circuit 111 that boosts the battery voltage to a predetermined voltage and applies it to the rotor coil 21; and a control circuit 110 that operates the booster circuit 111 when the battery discharge is detected.
It is equipped with.

The discharge state detection circuit 109 includes the rotor coil 21
The operating duty of the transistor 101 that drives the is 10
The battery discharge is detected when the voltage is 0%, or the battery discharge is detected when the battery voltage decreases.

[Function] In the vehicle charging device with the above configuration, when a large-capacity electrical load exceeding the output current of the charging generator is used, the battery enters a discharge state to supply the insufficient output current of the charging generator, and the battery voltage decreases. The excitation current of the rotor coil decreases. As a result, the output current of the charging generator becomes smaller, and the current shortage increases.

Here, the discharge state detection circuit detects the discharge of the battery, activates the booster circuit, boosts the battery voltage to a predetermined voltage, and applies this to the rotor coil.

In this way, a sufficient excitation current is supplied to the rotor coil, and as a result, a drop in the output current of the charging generator is avoided, and as a result, the current shortage is kept small and rapid discharge of the battery is prevented.

[Embodiment] In FIG. 1, a charging generator 2 that charges an on-vehicle battery 3 and an on-vehicle electric load "4" connected in parallel thereto has its output voltage adjusted to a constant regulated voltage by a regulator 1.

That is, the transistor 102 provided in the regulator 1
, Zener diode 103, resistor 104.105.1
06.107, the capacitor 108 constitutes a known constant voltage feedback circuit, and the transistor 101 switches the excitation current of the charging generator rotor coil 21.
The generated voltage generated in the stator coil 22 is maintained constant by controlling the operation of the stator coil 22 .

The generated voltage is converted into direct current by a rectifier 23, and then supplied to the battery 3 and the like.

109 is a discharge state detection circuit, and the transistor 1
The collector voltage of 01 is detected to know the operating duty, and when the operating duty becomes 100%, a "1" level output is generated.

Reference numeral 110 designates a control circuit which inputs the single-phase voltage of the stator coil 22 to detect the start of power generation, receives the start of power generation and the "1" level output of the discharge state detection circuit 109, and controls the DC/DC which is the boosting means in the subsequent stage. Converter 111 is activated.

The converter 111 boosts the output voltage of the charging generator 2 to a predetermined voltage (for example, 14.5V), and
It is applied to the rotor coil 21 through.

Note that the control circuit 110 has the “+” of the rotor coil 21.
The terminal output is fed back to accurately maintain the predetermined voltage.

Further, the "+" terminal is connected to the output terminal of the charging generator 2 via a diode 113.

In the charging device with the above configuration, the rotation speed of the charging generator is low when the vehicle is running at low speed or idling, and if a large electrical load is used in this state, the current supply capacity of the charging generator will be exceeded, so the output voltage will no longer be adjusted. Voltage (14,
5V), and the voltage drops to the battery's rated voltage (12V). Therefore, the excitation current of the rotor coil decreases, and if this continues, the current supply capacity of the charging generator will further decrease, and the load on the battery will increase.

In this state, the operating duty of transistor 101 should be 100%, and discharge state detection circuit 109 causes converter 111 to start operating.

The converter 111 boosts the input voltage of approximately 12V to 14.5V, and transfers this to the rotor coil 2.
Supply to 1.

In this way, a decrease in the power generation capacity of the charging generator is avoided, an increase in the load on the battery is prevented, and the battery does not run out.

In the above embodiment, feedback of the stator coil-phase output and the rotor coil "+" terminal output to the control circuit is not necessarily required.

[Effects] According to the vehicle charging device of the present invention configured as described above, even when the battery is in a discharge state due to an electrical load exceeding the current supply capacity of the charging generator, the excitation voltage of the rotor coil remains unchanged. By properly maintaining the battery, it is possible to effectively prevent the battery from dying due to an increase in battery load.

Note that the battery discharge state detection circuit may be one that detects the operating duty of the transistor as in the above embodiment, or one that detects the battery voltage (charging generator output voltage), both of which have the same effect.

[Brief explanation of the drawing]

FIG. 1 is an overall circuit diagram of the charging device, and FIG. 2 is a diagram showing the rotation speed dependence characteristics of the generator output current. 1...Regulator 101...Transistor 109...Battery discharge state detection circuit 110...Control circuit 111...DC/DC converter (boost circuit) 2...
・Charging generator 21...Rotor coil 22...Stator coil 3...Battery 4...In-vehicle electrical load

Claims (3)

[Claims] (1) In a vehicle charging device that excites the rotor coil of a charging generator with battery voltage and charges the battery with the generated voltage generated in the stator coil, the battery voltage is set to a predetermined voltage. A charging device for a vehicle, comprising: a booster circuit that boosts the voltage to the rotor coil and applies the voltage to the rotor coil; and a control circuit that operates the booster circuit when the battery discharge is detected. (2) Claim 1, wherein the discharge state detection circuit is set to detect battery discharge when the operating duty of the transistor that drives the rotor coil is 100%.
Charging device for the vehicle described (3) The vehicle charging device according to claim 1, wherein the discharge state detection circuit is set to detect battery discharge based on a decrease in the battery voltage.