Electrical charge control apparatus and method for photovoltaic energy conversion systems

A method of multiple setpoint charge control for controlling the charging of a rechargeable electrical energy storage device by an electrical energy source, said method comprising:

• connecting one or more charge setpoint control terminations to one of the three electrical potential contacts storage device "+", no contact (NC), and common "-";
• monitoring the voltage of said storage device, and producing a bias voltage indicative of storage device state-of-charge and a reference voltage indicative of a predetermined charged level of the storage device;
• providing charge control, including termination and resumption of storage device charging, based on the measured values of said bias voltage and said reference voltage;
• providing a plurality of bias voltage possibilities by means of charge setpoint control terminations;
• measuring charge control apparatus temperature--and employing temperature compensation to maintain charge setpoint thresholds essentially constant with charge control apparatus temperature;
• measuring storage device temperature and employing temperature compensation to continuously modify charge setpoint thresholds in a predefined manner in accordance with temperature dependent storage device charging characteristics.

A charge control apparatus for controlling the charging of a rechargeable electrical energy storage device by an electrical energy source, said apparatus comprising charge control means, driver means, and setpoint control means, said setpoint control means comprising:

• means for monitoring the voltage of said rechargeable electrical energy storage device;
• means for producing a reference voltage indicative of a predetermined charged level of the storage device;
• means for producing a bias voltage indicative of said monitored storage device voltage;
• multiple charge setpoint control means capable of producing a plurality of bias voltage conditions, each bias voltage condition produced thereof corresponding to a predefined charge setpoint condition, including charge termination voltage threshold and charge resumption voltage threshold;
• one or more charge setpoint control terminations operative to effect said multiple charge setpoint control;
• comparator means for comparing the bias voltage potential and the reference voltage potential, said comparator means producing a first condition control signal for the termination of charging or reduction to float charging of the storage device, in response to said bias voltage potential exceeding the level of said reference voltage potential, and a second condition control signal for the resumption of high-rate charging of the storage device, in response to said bias voltage potential falling below said reference voltage potential, said second condition control signal occurring at a lower storage device voltage than said first condition signal, the difference in storage device voltage for said first and second conditions determined by hysteresis feedback means acting through comparator means.

A charge control apparatus for controlling the charging of a rechargeable electrical energy storage device by an electrical energy source, said apparatus comprising charge control means, driver means, and setpoint control means, said setpoint control means comprising:

• multiple charge setpoint control means capable of producing a plurality of bias voltage conditions, each bias voltage condition produced thereof corresponding to a predefined charge setpoint condition, including charge termination voltage threshold and charge resumption voltage threshold;
• one or more charge setpoint control terminations operative to effect said multiple charge setpoint control;
• temperature compensation means operative to measure the internal temperature of charge control apparatus and modify in a predefined manner said bias voltage employed in multiple charge setpoint control, in order to maintain charge setpoint thresholds substantially constant with changes in charge control apparatus temperature;
• means for sensing and measuring storage device temperature, said storage device temperature sensing and measuring means being operative to continuously modify charge setpoint thresholds, including charge termination and resumption voltage thresholds, in a predefined manner in accordance with temperature dependent storage device charging characteristics.

A charge control apparatus for controlling the charging of a rechargeable electrical energy storage device by an electrical energy source, said apparatus employing pulse-width-modulation charge control comprising:

• multiple charge setpoint control means capable of producing a plurality of bias voltage conditions, each bias voltage condition produced thereof corresponding to a predefined charge setpoint condition, including pulse-width-modulation charge termination voltage threshold and charge resumption voltage threshold;
• one or more charge setpoint control terminations operative to effect said multiple charge setpoint control;
• temperature compensation means operative to measure the internal temperature of charge control apparatus and modify in a predefined manner said bias voltage employed in multiple charge setpoint control, in order to maintain charge setpoint thresholds substantially constant with changes in charge control apparatus temperature;
• means for sensing and measuring storage device temperature, said storage device temperature sensing and measuring means being operative to continuously modify charge setpoint thresholds, including pulse-width-modulation charge termination and resumption voltage thresholds, in a predefined manner in accordance with temperature dependent storage device charging characteristics.