Control system for an engine-driven AC generator

A control system for an engine driven generator including a field coil wherein the generator is coupled to a battery, wherein the system has control means for providing on and off signals for switching the field current to the field coil of the generator on and off respectively in response to a comparator which compares the battery voltage with a reference voltage for developing an on time for switching said field current on, wherein the control means comprises:

• a controller for detecting a present on time;
• means for determining whether said present on time equals or exceeds a predetermined control period set by said controller;
• and
• means for forcibly switching said control means to temporarily provide said off signal and switch said field current off for a predeterdined off time set by said controller when said on time equals or exceeds said predetermined control period.

A control system for an engine driven AC generator connected in parallel to a battery, wherein a field winding of the generator is controlled in on and off states for on and off times respectively by a controller in response to an output signal of a comparator which compares the battery voltage with a reference voltage for developing an on time for switching said field winding into an on state so that said battery voltage is caused to change to said reference voltage, and wherein said field winding is forcibly switched into said on and off states a number of times, characterized in that the controller includes:

• means for measuring and holding a present on time of the field winding;
• means for detecting that the present on time is longer than a previous on time by a present prescribed time which is variably set by said controller a s function of a previous prescribed time and the number of forcible switches of the field widing to the off state;
• and
• means for forcibly switching the field winding of the generator to the of state temporarily for an off time if said present on time is longer than said previous on time by said prescribed time.

A control system for an engine driven AC generator connected in parallel with a battery, wherein the generator includes a field coil and the field coil current for the generator is controlled by a controller to be switched on and off in response to an output signal of a comparator for comparing the battery voltage with a predetermined reference voltage in order that the battery voltage is caused to be brought to the level of the reference voltage said control system for the engine driven generator comprising:

• means for switching said reference voltage of said comparator between a high voltage level and a low voltage level so that said reference voltage is set at said high voltage level or said low voltage level according to electrical load conditions and engine operating conditions;
• means for detecting that the field coil current for the generator has continued on for a predetermined first period of time;
• means for detecting that the field coil current for the generator has continued on for a predetermined first period of time;
• means for forcibly switching the field coil current off for a predetermined second period of time set by said controller when the above detection is made;
• and
• means for varying said first period according to said high or low voltage level of said reference voltage.

An AC generator system including a field coil, and a voltage regulator including a comparator for comparing a battery voltage with a reference voltage and outputting a pulse signal to the field coil, comprising:

• timer means for detecting a present on time of the pulse signal;
• first means for detecting whether the present on time equals or exceeds a predetermined period;
• and
• second means for forcibly switching said field coil off by temporarily providing an off signal to the field coil for a predetermined off period regardless of the output of the comparator, in response to the first means.