Control arrangement for increasing the available output from a source
A control arrangement for use in controlling the electrical supply from a power supply unit including an internal capacitance to an output is described, the control arrangement comprising an inductor, a switch arranged in parallel with internal capacitance, and a controller operable to control the operation of the switch such that closing of the switch results in the formation of an LCR circuit, the internal capacitance forming the capacitance of the LCR circuit. An associated control method is also described.
1. A control arrangement for use in controlling the electrical supply from a power supply unit including an internal capacitance to an output, the control arrangement comprising an inductor of small inductance that matches the internal capacitance, a switch arranged in parallel with internal capacitance, and a controller operable to control the operation of the switch such that closing of the switch results in the formation of an LCR circuit, the internal capacitance forming the capacitance of the LCR circuit, wherein the controller is operable to cause the switch to move between open and closed positions at a high frequency in the range of 150 kHz-700 kHz.
2. An arrangement according to claim 1 and in which no maximum power point tracking algorithm is provided.
3. An arrangement according to claim 1 , wherein the internal capacitance is a variable capacitance, and the controller causes the switch to move between its opened and closed positions at a frequency chosen to maintain resonance, or a harmonic of a frequency which would maintain resonance, depending upon the instantaneous internal capacitance.
4. An arrangement according to claim 1 , wherein the supply unit comprises a solar panel.
5. An arrangement according to claim 1 , wherein the internal capacitance is formed, at least in part, for the junction capacitance of a pn junction diode located within the unit.
6. An arrangement according to claim 1 , in which two inductances are provided in parallel with one another, a respective switch being associated with each inductance.
7. An arrangement according to claim 6 , wherein each inductance forms part of a bifilar winding, and wherein blocking diodes are provided.
8. A method for controlling the output of a power supply unit using a control arrangement as claimed in claim 1 , the method comprising the steps of:
opening the switch, thereby allowing the internal capacitance of the unit to become charged;
closing the switch, thereby allowing the internal capacitance of the unit to discharge, increasing the current supplied to the inductor; and
re-opening the switch, thereby allowing the internal capacitance of the unit to become recharged whilst extracting energy from the inductor to satisfy the electrical demand of a load,
wherein the opening and closing of the switch is undertaken at a high frequency in the range of 150 kHz to 700 kHz.
9. A method according to claim 8 , wherein opening and closing of the switch is controlled by a controller which causes the switch to move between its opened and closed positions at the high frequency.
10. A control arrangement for use in controlling the electrical supply from a power supply unit including an internal capacitance to an output, the control arrangement comprising an inductor, a switch arranged in parallel with internal capacitance, and a controller operable to control the operation of the switch such that closing of the switch results in the formation of the LCR circuit, the internal capacitance forming the capacitance of the LCR circuit, wherein the internal capacitance is a variable capacitance, and the controller causes the switch to move between its open and closed positions at a frequency chosen to maintain resonance, or a harmonic of a frequency which would maintain resonance, depending upon the instantaneous internal capacitance.