Abstract: A permanent magnet made of ferrite magnet material used for a generator may be irreversibly demagnetized by a factor such as current supplied to a field coil, temperature of the permanent magnet and/or output current of an armature coil. When the field current exceeds a preset value, and also the output current exceeds a preset value, the field current is limited to prevent the irreversible demagnetization. Thus, the irreversible demagnetization of the permanent magnet can be prevented, while ensuring a sufficient amount of the output power. It is also effective that the field current or armature current is limited when the temperature of the permanent magnet is in a range of possible irreversible demagnetization.

Abstract: A generator control device disposed in a generator has a signal terminal to be connected to an outside control unit. The control device is composed of a voltage regulating circuit, a first circuit for controlling the regulating circuit according to a potential change of the signal terminal and a second circuit for changing potential level of the signal terminal according to a generator condition. The generator condition signal is transmitted through a signal wire to the outside control unit, and a switch-on signal of the ignition switch is sent to the control device through the signal wire from the outside control unit.

Abstract: A generation-stop detection system of an alternator is provided. A unit provides a generation-stop condition signal when an output voltage of the alternator is lower than a reference voltage. A rotation speed detection unit detects a rotation speed. A reference voltage changing unit changes the reference voltage proportionally to the rotation speed of the alternator. A warning signal unit provides a warning signal if the generation-stop condition signal is provided at a rotation speed lower than a predetermined speed. The warning signal is maintained even when the rotation speed of the alternator becomes higher than the predetermined speed. The warning signal is interrupted when the output voltage of the alternator is higher than the voltage of the battery.

Abstract: An inductive load driving apparatus for controlling current supplied from a battery to an inductor such as a generator field coil is composed of a first N-channel MOSFET switching element connected between a high-side terminal of the inductor and a high-side terminal of the battery, a second N-channel MOSFET switching element connected in parallel with the inductive load and a protection circuit having a back-flow current detecting element turning off the second N-channel MOSFET switching element when the inductor does not generate back-flow current. The second N-channel MOSFET switching element is turned on when the first N-channel MOSFET switching element is turned off and turned off when the first switching element is turned on. The first and second N-channel MOSFET switching elements are disposed integrally with each other on a semiconductor chip.

Abstract: To provide a vehicle power generating apparatus capable of transmitting plural kinds of control signals from an external control device to a generated voltage control unit provided in a generator for power generation control while curbing increases in the size of apparatus or wiring required and without degrading the noise reduction characteristics, a generated voltage control device is normally disposed integrally with a generator for maintaining the generated voltage at a predetermined target level. For transmission of a vehicle condition signal from an external control device to the generated voltage control device, the vehicle condition signal is converted into a binary pulse train signal before being transmitted. The generated voltage control device holds the binary pulse train signal received or a vehicle condition signal decoded from the binary pulse signal until the next reception. Thereby, complicated power generation control can be achieved with a small amount of communications.

Abstract: The rotor of a generator is provided with permanent magnets to ensure start-up of electricity generation without externally supplied field current after a vehicle engine starts. When the generation is detected, the external field current is supplied from a battery so that the battery is charged by the generator, thereby to prevent battery discharge in a low speed range.

Abstract: Duty ratio of a power switching transistor connected to the field coil is controlled according to whether or not a high-power load is connected. When the high power load is not connected, the duty ratio is made 60%, for example, so that excessive power not generated. On the other hand, when the high power load is connected, the duty ratio is increased to 100% so that full power is generated by the generator. The power switching transistor is also controlled according to the battery voltage in a well known manner.

Abstract: The present invention relates to a device which supplies a field current to the field coil of an alternator for a vehicle in a gradually changing manner. In the device, a pulse voltage which has a pulse width corresponding to a phase difference between output signals of first and a second counters (15 and 16) is generated by a maximum duty ratio limiting circuit (19). When the alternator output voltage becomes higher than a reference voltage, the full-scale count time of the second counter is shortened relative to the full-scale count time of the first counter. On the other hand, when the output voltage becomes lower than the reference voltage, the same is elongated to thereby increase the phase difference. A switching transistor (12) is provided to control the field current supplied to the alternator field coil in response to the above pulse voltage.