DE112012007202T5 - Systems and methods for controlling regulators for maximum power point tracking - Google Patents

Abstract

One method of operating a Maximum Power Point Tracking (MPPT) controller, which includes a switch circuit configured to transfer power between an input terminal and an output terminal, includes the following steps: (a) in a first operating mode of the MPPT controller Causing a first switching device of the switching circuit to operate at a fixed duty cycle; and (b) in a second mode of operation of the MPPT controller, causing a switching device of the switching circuit to repeatedly switch between its conducting and non-conducting states to maximize an amount of power coupled out of a photovoltaic device electrically connected to the input port.

Description

background

worin

I_L

= photogenerierter Strom

R_S

= Reihenwiderstand

R_SH

= Nebenschlusswiderstand

I₀

= Sättigungs-Rückwärtsstrom

n

= Dioden-Idealitätsfaktor (1 für eine ideale Diode)

q

= Elementarladung

k

= Boltzmann-Konstante

T

= absolute Temperatur

I

= Ausgangsstrom an Zellenklemmen

V

= Spannung an Zellenklemmen Für Silizium bei 25 °C: kT/q = 0,0259 V.

Photovoltaic cells generate a voltage that varies with current, cell operating conditions, cell physics, cell defects and cell illumination. A mathematical model for a photovoltaic cell, as in 1 is shown modeling the output current as:

wherein

I _L

= photogenerated stream

R _S

= Series resistance

R _SH

= Shunt resistance

I ₀

= Saturation reverse current

n

= Diode ideality factor (1 for an ideal diode)

q

= Elementary charge

k

= Boltzmann constant

T

= absolute temperature

I

= Output current at cell terminals

V

= Voltage at cell terminals For silicon at 25 ° C: kT / q = 0.0259 V.

Typical cell output voltages are low and depend on the bandgap of the material used to make the cell. The cell output voltages can be as low as half a volt for silicon cells, well below the voltage needed to charge batteries or drive most other loads. Because of these low voltages, cells are typically connected in series with one another to form a module or array with a much higher output voltage than that produced by a single cell. In addition, sometimes two or more strings of multiple photovoltaic cells are electrically connected in parallel to increase the capacity.

Photovoltaic cells in the real world often have one or more microscopic defects. These cell defects can cause mismatch of series resistance R _S , shunt resistance R _SH, and photogenerated current I _L from cell to cell in one module. Further, the cell illumination may vary from cell to cell in a system of photovoltaic cells, and may even vary from cell to cell in a module, for reasons such as tree shadows, bird droppings, shielding parts of a cell or module, dust, dirt and other effects. These lighting mismatches can vary from day to day and with the time of day - a shadow can shift over a module during a day, and rain can wash away any dust or dirt that shades a cell.

According to Eq. 1, the output voltage is greatest at output current zero, and the output voltage V drops non-linearly with increasing output current I. 2 represents the effect of increasing current drawn from a photovoltaic device under constant illumination. When the current I is increased under constant illumination, the voltage V drops slowly, but when the current I is increased to an output current near the photocurrent I _L , the output voltage V drops sharply. Similarly, the cell power, the product of current and voltage, increases as the current I increases until the falling voltage V overcomes the effect of the rising current, whereupon further increases in the current I drawn from the cell cause the power P to rapidly decrease reduced. For a given illumination, each cell, module and array of cells and modules therefore has a maximum power point (MPP) representing the voltage-current combination at which the output power from the device is maximized. The MPP of a cell, a module, or an array changes with temperature and illumination, and therefore the photogenerated current I _{L changes} . The MPP of a cell, module, or assembly may also be affected by factors such as shading and / or aging of the cell, module, or assembly.

Maximum Power Point Tracking (MPPT) controllers for operating a photovoltaic device at or near its maximum power point have been proposed. These regulators typically determine an MPP voltage and current for a photovoltaic device connected to its input and adjust its effective impedance to hold the photovoltaic device at the MPP.

Photovoltaic devices are typically subjected to one or more manufacturing tests. For example, a photovoltaic device is often characterized using a "flash test" in which the device is exposed to light of known intensity, such as from a "1 sun" (1000 watts per square meter) light source, while a load of the device is from open to short Voltage and current data are recorded during the load sweep, and open circuit voltage (Voc), short circuit current (Isc) and maximum power point (Pmp) power of the device are determined from the recorded data These characteristics of the device are used, for example to ensure the quality of the device and / or to screen out devices according to Voc, Isc and / or Pmp.

As another example, photovoltaic devices are often subjected to electroluminescent (EL) tests one or more times during manufacture of the device. The EL test involves driving a test current through the photovoltaic device in a direction opposite to that in which the current normally flows through the device, thereby causing the device to emit infrared light. The infrared light is imaged to detect imperfections of the device, such as cracks in the device, thereby helping to ensure the quality of the device.

A photovoltaic device may also be exposed to reverse current, i. Current flowing through the device in an opposite direction to that in normal operation. For example, consider a scenario in which a first and a second string of photovoltaic devices are electrically connected in parallel and each string contains a plurality of photovoltaic devices connected in series. Forward current flows through both strings if the strings have identical current-voltage characteristics, with the current-voltage characteristic of a string depending on both its physical properties and operating conditions. For example, consider a situation where the first string is exposed to strong sunlight and the second string is mostly shadowed. This illumination difference causes the first string to produce a larger photogenerated current than the second string, so the strings have different current-to-voltage characteristics that may potentially cause reverse current to flow through the second string.

Summary

In one embodiment, a method of operating a maximum power point tracking (MPPT) controller including a circuit configured to transfer power between an input port and an output port comprises the steps of: (a) in a first mode of operation of the MPPT controller causing a first switching device of the circuit to operate at a fixed duty cycle; and (b) in a second mode of operation of the MPPT controller, causing a control switching device of the circuit to repeatedly switch between its conductive and non-conductive states to maximize a power output coupled out of a photovoltaic device electrically coupled to the input terminal.

In one embodiment, a method of testing a photovoltaic device electrically connected to an input terminal of a Maximum Power Point Tracking (MPPT) controller, the MPPT controller including a circuit therefor, includes power between the input port and an output port of the MPPT controller. To transfer the regulator, the following steps: (a) driving a test current into the output terminal of the MPPT controller; (b) detecting the presence of the test current; and (c) in response to detecting the presence of the test current, causing the circuit to provide a path for the test current from the output terminal to the photovoltaic device.

In one embodiment, a Maximum Power Point Tracking (MPPT) controller includes an input and an output port, a circuit configured to transfer power between the input and output ports of the MPPT controller, and a control subsystem. The control subsystem is configured to (a) cause a first switching device of the circuit to operate at a fixed duty cycle in a first operating mode of the MPPT controller, and (b) in a second operating mode of the MPPT controller, a control switching device of the Circuit to repeatedly switch between its conducting and non-conducting state to one from one to the Input terminal electrically connected photovoltaic device to maximize disengaged amount of electrical power.

Brief description of the drawings

1 shows a model of a photovoltaic cell.

2 shows a graph of voltage and power as a function of current for a photovoltaic cell.

3 FIG. 10 illustrates a photovoltaic power generation system according to an embodiment including an MPPT controller including at least two modes of operation.

4 verifies EL testing of a photovoltaic device of the power generation system 3 according to an embodiment.

5 detects flash testing of the photovoltaic device of the power generation system 3 according to an embodiment.

6 restores reverse current operation of the photovoltaic device of the power generation system 3 according to an embodiment.

7 sets forth a possible method of operating the MPPT controller 3 according to an embodiment.

8th According to one embodiment, illustrates a method of determining whether a fixed duty cycle mode is appropriate.

9 According to one embodiment, another method of determining whether a fixed duty cycle mode is appropriate.

10 According to one embodiment, illustrates a method of determining when to exit a fixed duty cycle mode.

11 According to one embodiment, another method of determining when to exit a fixed duty cycle mode.

12 According to one embodiment, it is another photovoltaic power generation system that includes an MPPT controller that includes at least two modes of operation.

13 According to one embodiment, it is a photovoltaic power generation system including multiple MPPT controllers, each MPPT controller comprising at least two modes of operation.

14 According to one embodiment, it is a photovoltaic power generation system that includes three parallel strings of the MPPT controller of FIG 3 includes.

15 shows a curve of the reverse current versus voltage for a photovoltaic cell.

16 shows, according to one embodiment, an example of a linear output current-voltage characteristic.

17 shows, according to one embodiment, an example of a non-linear output current-voltage characteristic.

Detailed description of the embodiments

As described above, an MPPT controller can be used to operate a photovoltaic device at or near its MPP. However, conventional MPPT controllers typically interfere with manufacturing testing of the photovoltaic device. For example, conventional MPPT controllers can prevent backward test current and / or overheat when subjected to EL testing. As another example, transfer characteristics of conventional MPPT controllers change during the flash test and thereby interfere with the determination of Voc, Isc and Pmp. Accordingly, photovoltaic devices typically can not be electrically connected to conventional MPPT controllers during factory testing of the device.

This limitation of conventional MPPT controllers is a particularly serious drawback in applications where multiple MPPT controllers are assembled with multiple photovoltaic devices in a single package. In these applications, the MPPT controllers typically provide a portion of the interconnect between the photovoltaic devices. Thus, temporary connectors are required to interconnect the photovoltaic devices during the manufacturing test because the MPPT controllers may not be present during the test.

In addition, conventional MPPT controllers may overheat or otherwise operate incorrectly when exposed to reverse current. Accordingly, conventional MPPT controllers may not be suitable for parallel string applications.

Applicants, however, have developed MPPT controllers that partially or completely overcome one or more of the problems described above. These MPPT controllers include a fixed duty cycle mode of operation in addition to one or more other operating modes, thereby allowing the regulators to be used during one or more manufacturing tests and / or with reverse current. For example, certain embodiments of the controllers support flash or EL tests. Accordingly, the new MPPT controllers described herein potentially facilitate fabrication and testing of photovoltaic devices, particularly in applications that include a number of photovoltaic devices and MPPT controllers assembled in a package.

3 represents a power generation system 300 This is an MPPT controller 302 that is between a photovoltaic device 304 and a load 306 electrically connected. As described below, the MPPT controller supports 302 at least one fixed duty cycle mode of operation and an MPPT operating mode, thereby potentially enabling the manufacturing test of the photovoltaic device 304 with electrically connected MPPT controller 302 and potentially supports reverse current operation.

The MPPT controller 302 includes an input port 308 containing the input terminals 310 . 312 , and an output terminal 314 containing the output terminals 316 . 318 , A positive clamp 320 the photovoltaic device 304 is electrically connected to the input terminal 310 connected, and a negative terminal 322 the photovoltaic device 304 is electrically connected to the input terminal 312 connected so that the photovoltaic device 304 with the input connector 308 electrically connected in series. The clamps 310 . 320 form part of a positive supply node or supply rail (Vddh), and the terminals 312 . 322 form part of a reference supply node or supply rail (Vss). The photovoltaic device 304 For example, a photovoltaic module including a plurality of interconnected photovoltaic cells, a single photovoltaic cell or a multiple photovoltaic cell.

The system 300 optionally includes one or more input capacitors 324 that over the input terminal 308 are electrically connected. The capacitors 324 help, the ripple component of the input current Iin of the regulator 302 thereby helping to minimize the amount of ripple current passing through the photovoltaic device 304 flows. A low amount of ripple current through the photovoltaic device 304 in turn favors efficient operation of the device. In certain embodiments, where the MPPT controller 302 switching at a relatively high frequency, such as at 500 kilohertz or higher, are the capacitors 324 Multilayer ceramic capacitors to favor small capacitor size and long capacitor life.

The MPPT controller 302 contains a circuit 326 that is above the input connector 308 electrically connected. The circuit 326 contains a control switching device 328 between the input terminal 310 and a switching node Vx is electrically connected, and a free-running switching device 330 between the switching node Vx and the input terminal 312 electrically connected. The output terminal 316 is electrically connected to the switching node Vx, and the output terminal 318 is with the input terminal 312 electrically connected. In this document, a switching device includes, but is not limited to, a bipolar junction transistor, a field effect transistor (eg, an N-channel or P-channel metal oxide semiconductor field effect transistor (MOSFET), such as a laterally diffused metal oxide Semiconductor transistor (LDMOS), a junction field effect transistor, a metal-semiconductor field effect transistor), an insulated gate bipolar junction transistor, a thyristor, or a controllable one Silicon rectifier. Although the switching devices 328 . 330 As N-channel enhancement field effect transistors, the switching devices could 328 . 330 be replaced by alternative switching devices without departing from the scope of the present.

Weight 306 is with the output connector 314 electrically connected in series to form part of an output circuit 332 to form the load 306 with the circuit 326 connects electrically. Weight 306 contains, for example, an inverter or a battery charger. One or more output capacitors 334 are over the load 306 electrically connected to absorb the ripple component of the output current Iout. The capacitors 334 however, are optionally omitted in embodiments where the load 306 contains significant capacity, such as in embodiments, where the load 306 is an inverter with significant input capacity. In certain embodiments, where the MPPT controller 302 switching at a relatively high frequency, such as at 500 kilohertz or higher, are the capacitors 334 Multilayer ceramic capacitors to favor small capacitor size and long capacitor life. The output circuit 332 contains an energy storage inductance 336 , In some embodiments, the energy storage inductance includes 336 one or more discrete inductors, as in 3 shown symbolically. However, in some other embodiments, discrete energy storage inductances are eliminated, and those that form the loop that make up the output circuit 332 forms, belonging "parasitic" connection inductance serves as energy storage inductance 336 ,

The MPPT controller 302 also contains a rule subsystem 338 , The circuit 326 , the energy storage inductance 336 and the capacitors 334 together form one through the rule subsystem 338 regulated down-converter. In an MPPT operating mode of the controller 302 is the rule subsystem 338 designed to switch the circuit 326 so that the buck converter power from the input terminal 308 to the output terminal 314 transmits and thereby power from the photovoltaic device 304 to the load 306 transfers. More specifically, the rule subsystem causes 338 the control switching device 328 repeatedly toggling between its conducting and nonconducting states, typically at a frequency of at least 100 kilohertz, to power from the input port 308 to the output terminal 314 transferred to. The switching device 328 is referred to as a "rule" switching device because the ratio of input voltage Vin to output voltage Vout across the load 306 a function of the duty cycle of the switching device 328 is.

The rule subsystem 338 Also controls the switching of the free-running switching device 330 such that it performs a free-running function, or in other words, such that the free-running switching device 330 a path for between the output terminals 316 . 318 flowing output current Iout provides when the control switching device 328 in its non-conducting state. In some alternative embodiments, the free-running switching device is 330 is replaced by an alternative free-wheeling device, such as a diode whose anode is electrically connected to the reference node Vss, and whose cathode is electrically connected to the switching node Vx.

The MPPT controller 302 optionally further includes a stream reconstruction subsystem 340 configured to generate a signal Io representative of the output current Iout coming from the output terminal 314 flows. In some embodiments, the power reconstruction subsystem uses 340 for generating the signal Io systems and methods described in one or more of U.S. Pat. Nos. 6,160,441 and 6,445,244 to Stratakos et al. are disclosed, each of which is incorporated herein by reference. However, the power reconstruction subsystem 340 be carried out in other ways without departing from the scope of the present In some embodiments, signal Io is used for MPPT to verify the photovoltaic device 304 to detect and / or reverse current to recognize, that is, when the output current Io has a negative value.

The MPPT controller 302 further includes optionally a voltage regulator 342 which generates from Vddh / Vss a "self-powered" power supply node or rail (Vcc). Vcc is used, for example, to at least partially the rule subsystem 338 to supply as shown.

Although input capacitors 324 , Output capacitors 334 and energy storage inductance 336 as external to the MPPT controller 302 shown could be one or more of these components in the controller 302 be integrated without departing from the scope of the present. Also, some or the whole of the MPPT controller is 302 In certain embodiments, they are implemented in a common integrated circuit to favor small package size, small parasitic impedance between components, and fast signal transfer times. In these embodiments, the integrated circuit is optional with the photovoltaic device 304 Packed in a housing to small system size and minimum Impedance between the device 304 and the controller 302 to favor. However, the MPPT controller is 302 is not limited to an integrated circuit design and could instead be partially or fully formed from discrete components.

As described above, the MPPT controller 302 at least two modes of operation, namely an MPPT mode of operation and a fixed duty cycle mode of operation. In MPPT operating mode, the control subsystem initiates 338 the control switching device 328 repeatedly toggling between its conducting and non-conducting states, at least substantially one of a photovoltaic device 304 decoupled and to the load 306 to maximize the delivered amount. For example, in some embodiments, the rule subsystem maximizes 338 the power in the input terminal 308 and thereby maximizes those from the photovoltaic device 304 decoupled power. In some other embodiments, the rule subsystem maximizes 338 the power from the output terminal 314 What effectively removes the photovoltaic device 304 decoupled power maximizes, as the power from the output port 314 same as the power in the input terminal 308 if you have losses in the MPPT controller 302 neglected.

The MPPT controller 302 may be configured to directly maximize the power of the input terminal or output terminal in MPPT mode of operation. For example, in some embodiments, the rule subsystem estimates 338 the input power from the product of the input voltage Vin and the input current Iin and controls the operation of the circuit 326 to maximize input power. As another example, the rule subsystem estimates 338 the output power of the product of the output current Iout and the output voltage Vout or the average value of the switching node voltage Vp and controls the operation of the circuit 326 to maximize output power. However, the MPPT controller can 302 alternatively, be designed to maximize the input or output port power by maximizing a signal related to input or output port power. For example, the controller maximizes 338 in a particular embodiment in which the output current Iout is substantially constant, the output terminal power is achieved by maximizing the output voltage Vout or an average of the switching node / output terminal voltage Vp.

In fixed duty cycle mode, the control subsystem initiates 338 the control switching device 328 to work at a fixed duty cycle to get a known DC transformation between input terminal 308 and output connection 314 to reach. In many embodiments, the rule subsystem causes 338 the control switching device 328 operate at a large fixed duty cycle, such as a ninety percent or one hundred percent duty cycle, to facilitate testing and minimize losses, as described below. In the context of this document, "duty cycle" refers to the portion of each switching cycle in which a switching device operates in its conducting state. For example, consider a scenario in which the control switching device 328 switches between its conducting and non-conducting state at a frequency of 100 kilohertz, so that the switching device 328 has a switching period of ten microseconds. When the control switching device 328 Nine microseconds of each switching period operates in its conducting state, the control switching device 328 a duty cycle of ninety percent on. When the control switching device 328 operates continuously in its conductive state, the control switching device 328 a duty cycle of one hundred percent.

Operating the control switching device 328 at a fixed duty cycle, determining Voc, Isc and Pmp facilitates measured Iout and Vout values during flash testing. In particular, the MPPT controller works 302 as a fixed DC voltage transformer, when the control switching device 328 operates at a fixed duty cycle, so that the following relationships apply during operation in continuous line mode, where D is the duty cycle of the control switching device 328 is: Vout = D · Vin Eq. 2 Iout = Iin / D Eq. 3

Thus, the voltage and current of the photovoltaic device 304 In the fixed duty cycle operation, it can be determined simply by scaling the output voltage measurement value Vo and the output current measurement value Io by D. If the MPPT controller 302 while not working at a fixed duty cycle during flash testing, it would be difficult to control the voltage and current of the photovoltaic device 304 from the measurements for Vo and Io, since the duty cycle would vary due to the MPPT function.

In addition, it facilitates operation of the control switching device 328 at a fixed duty cycle EL testing by allowing the amount of test current through the photovoltaic device 304 to be determined without further ado. As described above, the ratio of regulator input and output current is a function of the duty cycle. Thus, the amount of EL test current through the photovoltaic device 304 simply by scaling the amount of to the output port 314 applied EL test current can be determined when the duty cycle is fixed. If the MPPT controller 302 whereas, during EL testing, it did not operate at a fixed duty cycle, it would be difficult to control the amount of current of the photovoltaic device 304 from the to the output terminal 314 applied current, since the duty cycle would vary due to the MPPT function.

Further facilitates operation of the control switching device 328 at a high duty cycle flash and EL testing as well as reverse current operation, favoring low amount of current. As from Eq. 3, the magnitude of the regulator output current is inversely proportional to the magnitude of the regulator input current. Thus, for a given amount of input current, the amount of output current is minimized by operating at a large duty cycle, such as a duty cycle of at least ninety percent. A low amount of output current in turn favors low losses of the regulator 302 because there are losses in the controller 302 generally increase with increasing amount of output current. Low losses in the controller 302 Helps to minimize warm-up during flash tests, EL testing and reverse current operation. Low losses in the controller 302 also help to minimize the amount of current required during flash tests and EL tests. Low losses of the regulator 302 may be particularly important during EL testing because EL testing typically requires a relatively high amount of test current.

Although reverse power operation is generally described herein in connection with fixed duty cycle operation, it should be understood that the duty cycle need not be fixed during reverse power operation because a fixed DC transformation is not required. Instead, the duty cycle need only be large, such as ninety percent or greater, to achieve low losses, as described above.

4 shows an example of the EL testing of the photovoltaic device 304 with the MPPT controller connected to it electrically 302 , One electrically with the output connection 314 series-connected test current source 402 injects a test current I_test into the output terminal 314 , I_test is considered a "backward" test current because it is in the output terminal 314 in a direction opposite to the output current Iout during normal system operation. The MPPT controller 302 operates in its fixed duty cycle mode, with the rule subsystem 338 the control switching device 328 caused to operate at a fixed duty cycle and thereby a known DC transformation between input terminal 308 and output connection 314 provided. The current I_test flows through the photovoltaic device 304 in a direction opposite to that of normal operation, what the photovoltaic device 304 causes infrared light 404 which is reproduced for purposes of quality assurance of the device. In embodiments in which the energy storage inductance 336 is one or more discrete inductors, is the inductance 336 optionally omitted during the EL test.

5 shows an example of the flash testing of the photovoltaic device 304 with the MPPT controller electrically connected to it 302 , A light source 502 projects light 504 known intensity on the photovoltaic device 304 while a load 506 from idle to short circuit. The output voltage Vout and the output current Iout are recorded during the load pass, and these values are used to represent Voc, Isc and Pmp of the photovoltaic device 304 to determine. The MPPT controller 302 works in its fixed-duty mode during the flash test, so the rule subsystem 338 the control switching device 328 caused to switch at a fixed duty cycle. Operating the control switching device 328 at a fixed duty cycle, a known DC transformation looks between the photovoltaic device 304 and the load 506 thereby facilitating measurement of the output current Iout during the load sweep. In embodiments in which the energy storage inductance 336 is one or more discrete inductors, is the inductance 336 optionally omitted during the flash test.

6 Fig. 10 shows an example of the reverse current operation of the photovoltaic device 304 with the MPPT controller connected to it electrically 302 , An external circuit (not shown), such as one or more photovoltaic devices connected in parallel, drives a reverse current I_reverse into the output terminal 314 , I_reverse is considered a "backward" stream because it is in the output port 314 in a direction opposite to the output current Iout during normal system operation. Of the MPPT controller 302 operates in its fixed duty cycle mode, with the rule subsystem 338 the control switching device 328 caused to operate at a large duty cycle and thereby provide a path for the reverse current I_reverse to flow through the photovoltaic device 304 provided. As described above, no fixed duty cycle is required for reverse current operation. Thus, in some alternative embodiments, the control switching device operates 328 at a large, non-fixed duty cycle, such as ninety percent or greater, when conducting I_reverse.

The rule subsystem 338 is optionally designed, a duty cycle of the control switching device 328 to cause it to rise to its fixed duty cycle when the MPPT controller is started 302 operate in its fixed duty cycle operating mode rather than starting immediately at the fixed duty cycle. Such control of the change in duty cycle, sometimes referred to as "soft start", helps eliminate parasitic transient associated with changes in operating condition.

In some embodiments, each time the MPPT controller is triggered 302 starts, the rule subsystem 338 the MPPT controller 302 to work in its fixed duty cycle mode. In some other embodiments, the MPPT controller operates 302 in its fixed duty cycle mode in response to an external signal, such as a signal generated by testers designed to perform flash and / or EL testing. In certain embodiments, the rule subsystem determines 338 whether operating mode with fixed duty cycle is appropriate, and if so, it operates the regulator 302 in its fixed duty cycle mode.

For example 7 a procedure 700 for operating the MPPT controller 302 which includes determining whether operation in the fixed duty cycle mode is appropriate. The procedure 700 For example, when the MPPT controller starts up 302 executed, so the controller 302 in its fixed duty cycle mode, if appropriate. However, that's the procedure 700 not to use when starting up the regulator 302 limited and could instead be executed in other situations, such as after a fault condition.

The procedure 700 begins with a decision step 702 determining whether operation in fixed duty cycle mode is appropriate. An example of the step 702 is determining by the rule subsystem 338 whether operation in fixed duty cycle mode is appropriate. Some specific examples of the step 702 are down regarding 8th and 9 described. If the decision step 702 determines that operation in fixed duty cycle mode is not appropriate, the procedure goes 700 proceed to MPPT mode of operation 704 , An example of the step 704 is that the rule subsystem 338 the MPPT controller 302 in its MPPT mode of operation.

If, on the other hand, the decision step 702 determines that operation is appropriate in the fixed duty cycle mode, the procedure goes 700 ahead to the step 706 with operation in fixed duty cycle mode. An example of step 706 is that the rule subsystem 338 the control switching device 328 caused to work at a fixed duty cycle of at least ninety percent. The decision step 708 determines whether operation is completed in fixed duty cycle mode. If not, the operation is running 706 in fixed duty cycle mode. If operation is completed in fixed duty cycle mode, the procedure advances to MPPT operation mode 704 , An example of the step 708 is the determination by the rule subsystem 338 whether operation is completed in fixed duty cycle mode. Some specific examples of the step 708 are down regarding 10 and 11 described.

The procedure 700 could be modified to include one or more additional modes of operation in addition to the MPPT mode 704 and the fixed duty cycle mode 706 to contain. For example, some alternative embodiments further include a bypass mode of operation in which the control switching device 328 operates in its non-conductive state and the free-running switching device 330 working in her senior state. In these alternative embodiments, the bypass mode of operation is entered, for example, by decision step 702 or 708 if operation in fixed duty cycle mode is not adequate or complete and the amount of input voltage Vin is too low to warrant MPPT operation. Operation then proceeds from Bypass mode to MPPT mode of operation 704 for example, if the amount of Vin increases sufficiently to support MPPT operation.

In some embodiments, the rule subsystem determines 338 based on characteristics of its operating environment, whether operation in fixed duty cycle mode is appropriate. For example 8th a procedure 800 for determining whether fixed duty cycle operating mode is appropriate when starting up an MPPT controller. The procedure 800 for example, as part of the step 702 of the procedure 700 executed. However, that's the procedure 800 not to use in the process 700 limited, but could be used in other situations. Besides, the step is 702 not to use in the process 800 limited.

The procedure 800 begins with the decision step 802 detecting the presence of an output terminal voltage prior to operation of the circuit at start-up when the devices of the circuit are in their non-conducting states. Existence of an output terminal voltage under these conditions indicates that the MPPT controller is powered from its output terminal rather than its input terminal, indicating possible presence of a test current and an EL test. For example, consider the EL test example of 4 , In this example, the test current source causes 402 in that a voltage Vp at the output terminal 314 exists before the circuit 326 starts to work. If, however, the source 402 would not be present, the output terminal voltage Vp before the operation of the circuit 326 typically substantially zero when the output port 314 would not be driven in any other way. Accordingly, the decision step determines 802 in that operation in the fixed duty cycle mode is appropriate if the magnitude of the output terminal voltage is greater than a threshold, the threshold being zero or a small positive value. An example of the step 802 is that the rule subsystem 338 before the operation of the circuit 326 when starting while the switching devices 328 . 330 in their non-conducting states, comparing the switching node or output terminal voltage Vp or a signal representing Vp to a threshold and the MPPT controller 302 causes it to operate in its fixed duty cycle mode if Vp is greater than a threshold.

If the decision step 802 determines that operation in fixed duty cycle mode is not appropriate, the procedure goes 800 proceeding to enter the MPPT mode of operation in step 804 , However, in some alternative embodiments, the method steps in step 804 instead of the MPPT mode in an alternative operating mode, such as in the bypass mode described above.

If, on the other hand, the decision step 802 determines that operation is appropriate in the fixed duty cycle mode, the procedure goes 800 proceeding to enter the fixed duty cycle mode in step 806 , However, some embodiments of the method are included 800 optional steps 808 and 810 , as shown. These steps delay entry into the fixed duty cycle mode until a power rail of the MPPT controller has reached a level necessary to support reliable controller operation.

In particular, the decision step compares 808 an amount of voltage on a regulator power rail, such as the amount of Vcc in the regulator 302 , with a minimum value (Vmin) required for reliable MPPT controller operation. If the amount of voltage of the power rail is greater than or equal to Vmin, the process proceeds to step 806 to enter the fixed duty cycle mode. Otherwise, the operation proceeds to step 810 in that the circuit is deactivated so that its switching devices are in their non-conducting states. The procedure 800 returns from step 810 to step 808 so that the circuit remains disabled until the voltage of the power rail reaches Vmin. An example of the steps 808 and 810 is that the rule subsystem 338 the switching devices 328 . 330 causes to remain in their non-conducting states until Vcc one for reliable operation of the converter 302 required minimum value reached.

Include the optional steps 808 and 810 in the procedure 800 may, in some embodiments, start up the MPPT controller 302 accelerate. For example, consider again the EL test example of 4 , The the rule switching device 328 converting transistor includes a body diode 344 with an anode electrically connected to the switching node Vx and one electrically connected to the input terminal 310 connected cathode. Accordingly, the test current I_test flows through the body diode 344 as indicated by the current I_diode in 4 shown in the positive power rail Vddh before the circuit 326 is in operation. The test current charges the positive power supply rail Vddh. In addition, the test current charges the self-operation power supply rail Vcc via the positive power supply rail Vddh and the voltage regulator 342 , Accordingly, the power supply rails Vddh and Vcc become in the fixed-duty-cycle mode from the output terminal during the EL test or during the reverse current operation 314 supplied. Delaying the operation in fixed duty cycle mode until Vcc one for reliable operation of the controller 302 required minimum value, favoring fast loading of Vddh / Vcc rails and subsequent operation in fixed duty cycle mode. If, on the other hand, the steps 808 . 810 are omitted, the free-running switching device 330 while charging the Vddh / Vcc rails, thereby delaying charging of the rails and operation in fixed duty cycle mode.

9 represents another procedure 900 for determining whether a fixed duty cycle mode is appropriate. The procedure 900 for example, as part of the step 702 of the procedure 700 executed. However, that's the procedure 900 not to use in the process 700 limited, but could be used in other situations. Besides, the step is 702 not to use in the process 900 limited.

The procedure 900 starts with step 902 determining whether current flowing from the output terminal of the MPPT regulator has a negative value, or in other words, whether current is flowing into the output terminal. Such a condition represents possible driving of the converter with a test current and associated EL test or reverse current operation. For example, consider the EL test example of FIG 4 , During the EL test drives the Prüfstromquelle 402 the test current I_test in the output terminal 314 so Iout has a negative value. As another example, consider the reverse flow example of 6 , An external circuit (not shown) drives a reverse current I_reverse into the output terminal 314 so Iout has a negative value. Accordingly, operation in the fixed duty cycle mode is appropriate if the output current value is less than a threshold Ith, where Ith is zero or a value near zero. Although step 902 however, if the output current is negative, it may still be desirable to set Ith to a value other than zero, such as a value slightly below zero, to erroneously trigger the fixed duty cycle mode due to errors in measuring the output current Iout to prevent. An example of the step 902 is comparisons by the rule subsystem 338 of the signal Io, which is the current from the output terminal 314 , with a threshold such as zero or near zero, and determining that fixed duty cycle operation is appropriate if the amount of Io is less than the threshold.

If the decision step 902 determines that operation in fixed duty cycle mode is not appropriate, the procedure goes 900 proceeding to enter the MPPT mode in step 904 , However, in some alternative embodiments, the method steps in step 904 instead of the MPPT mode in an alternative operating mode, such as in the bypass mode described above.

If, on the other hand, the decision step 902 determines that operation is appropriate in the fixed duty cycle mode, the procedure goes 900 proceeding to enter the fixed duty cycle mode in step 906 , However, some embodiments of the method are included 900 optional steps 908 and 910 , as shown. These steps are analogous to the steps 808 and 810 from 8th , delay entry into the fixed duty cycle mode until a power rail of the MPPT controller reaches a level necessary to support reliable controller operation.

10 represents a procedure 1000 determining when to exit the fixed duty cycle mode of operation. The procedure 1000 for example, as part of the step 708 of the procedure 700 executed. However, that's the procedure 1000 not to use in the process 700 but instead could be used to determine in other situations when to leave the fixed duty cycle mode. Besides, the step is 708 not to use in the process 1000 limited.

The procedure 1000 begins with a decision step 1002 determining if a predetermined time has elapsed. This predetermined time period is chosen to allow sufficient time to complete applicable tests of the photovoltaic device, such as EL and flash testing. If the specified time has not elapsed, the step repeats 1002 ; otherwise the process will proceed to enter the MPPT mode in step 1004 , An example of the steps 1002 . 1004 is that the rule subsystem 338 at the beginning of the operation in the fixed duty cycle mode, starts a timer and enters the MPPT mode after a predetermined time has elapsed. However, in some alternative embodiments, the method steps in step 1004 instead of the MPPT mode in an alternative operating mode, such as in the bypass mode described above.

11 represents a procedure 1100 determining when to exit the fixed duty cycle mode of operation. The procedure 1100 for example, as part of the step 708 of the procedure 700 executed. However, procedure is 1100 not to use in the process 700 limited, but could instead be used to determine in other situations when to leave the fixed duty cycle mode. Besides, the step is 708 not to use in the process 1100 limited.

The procedure 1100 begins with a decision step 1102 determining whether a voltage across the input terminal or a voltage that is a function of the input terminal voltage has dropped below a threshold. The threshold is typically chosen to be zero or near zero, so the step 1102 detects when the input terminal voltage or an associated voltage is substantially zero. A zero input terminal voltage may indicate completion of the photovoltaic device test. For example, the input terminal voltage is substantially zero upon completion of the flash test when a load goes from idle to short. As another example, the input terminal voltage may drop to near zero after removing an EL test current source. If the voltage is not lower than the threshold, step repeats 1102 ; otherwise the process will proceed to enter the MPPT mode in step 1104 ,

An example of the steps 1102 . 1104 is that the rule subsystem 338 compares the input terminal voltage Vin or the power rail voltage Vcc with a threshold value and enters the MPPT mode if the voltage is lower than the threshold value. However, in some alternative embodiments, the method steps in step 1104 instead of the MPPT mode in an alternative operating mode, such as in the bypass mode described above.

Flash testing may be difficult to detect in some applications because current flows through the photovoltaic device in its normal direction during flash testing. Accordingly, some embodiments of the regulator 302 are designed to remain in their fixed duty cycle mode upon completion of EL testing to allow subsequent flash testing while remaining in fixed duty cycle mode. The fixed duty cycle mode could also be operated in embodiments which, as described above 9 Detect negative output current by initially driving the output terminal with a reverse current.

Fixed duty cycle operating modes may also be implemented in MPPT controller applications with a topology other than a buck converter topology, such as a boost converter topology or a buck-boost topology. For example 12 a power generation system 1200 This is an MPPT controller 1202 that is between a photovoltaic device 1204 and a load 1206 electrically connected. The MPPT controller 1202 is similar to the MPPT controller 302 , but is designed to support an up-converter topology rather than a down-converter topology.

The MPPT controller 1202 includes an input port 1208 with the input terminals 1210 . 1212 and an output terminal 1214 with the output terminals 1216 . 1218 , A positive clamp 1220 the photovoltaic device 1204 is at the input terminal 1210 electrically connected, and a negative terminal 1222 the photovoltaic device 1204 is at the input terminal 1212 electrically connected, so the photovoltaic device 1204 with the input connector 1208 electrically connected in series. The clamps 1210 . 1220 form part of a positive supply node or supply rail (Vddh), and the terminals 1212 . 1222 form part of a reference supply node or supply rail (Vss). The photovoltaic device 1204 For example, a photovoltaic module including a plurality of interconnected photovoltaic cells, a single photovoltaic cell or a multiple photovoltaic cell.

The system 1200 optionally includes one or more input capacitors 1224 that over the input terminal 1208 are electrically connected. The capacitors 1224 contribute to the ripple component of the input current Iin of the regulator 1202 thereby helping to minimize the amount of ripple current passing through the photovoltaic device 1204 flows. The MPPT controller 1202 further includes one between the input terminal 1210 and a switching node Vx electrically connected energy storage inductance 1236 , The energy storage inductance 1236 may include one or more discrete inductors as shown.

The MPPT controller 1202 further includes one between the energy storage inductance 1236 and the output terminal 1214 electrically connected circuit 1226 , The circuit 1226 includes one between the switching node Vx and the input and output terminal terminals 1212 . 1218 electrically connected control switching device 1228 and one between the switching node Vx and the output terminal 1216 electrically connected free-running switching device 1230 , The output terminal 1218 is with the input terminal 1212 electrically connected. Although the switching devices 1228 . 1230 As N-channel enhancement field effect transistors, the switching devices could 1228 . 1230 be replaced by alternative switching devices without departing from the scope of the present.

Weight 1206 is with the output connector 1214 electrically connected in series. Weight 1206 contains, for example, an inverter or a battery charger. One or more output capacitors 1234 are over the load 1206 electrically connected to absorb the ripple component of the output current Iout. The capacitors 1234 however, are optionally omitted in embodiments in which the load 1206 contains significant capacity, such as in embodiments where the load 1206 is an inverter with significant input capacity.

The MPPT controller 1202 also contains a rule subsystem 1238 , The circuit 1226 , the energy storage inductance 1236 and the capacitors 1234 together form one through the rule subsystem 1238 regulated boost converter. In an MPPT operating mode of the controller 1202 is the rule subsystem 1238 designed, switching the circuit 1226 so that the boost converter has power from the input terminal 1208 to the output terminal 1214 transmits and thereby power from the photovoltaic device 1204 to the load 1206 transfers. More specifically, the rule subsystem causes 1238 the control switching device 1228 repeatedly toggling between its conducting and nonconducting states, typically at a frequency of at least 100 kilohertz, to power from the input port 1208 to the output terminal 1214 transferred to. The switching device 1228 is referred to as a "rule" switching device because the ratio of input voltage Vin to output voltage Vout across the load 1206 a function of the duty cycle of the switching device 1228 is.

The rule subsystem 1238 Also controls the switching of the free-running switching device 1230 such that it performs a free-running function, or in other words such that the free-running switching device 1230 a path for through the energy storage inductance 1236 flowing current provides when the control switching device 1228 in its non-conducting state.

The MPPT controller 1202 optionally further includes a stream reconstruction subsystem 1240 adapted to generate a signal Io which is from the output terminal 1214 represents flowing output current Iout. In addition, in some embodiments, the MPPT controller includes 1202 continue a voltage regulator 1242 which generates from Vddh / Vss a "self-powered" power supply node or rail (Vcc). Vcc is used, for example, to at least partially the rule subsystem 1238 to supply as shown.

Although input capacitors 1224 and output capacitors 1234 as external to the MPPT controller 1202 shown could be one or more of these components in the controller 1202 be integrated without departing from the scope of the present. In addition, in cases where the energy storage inductance could 1236 consists of one or more discrete inductors, the inductors external to the regulator 1202 be arranged. Next is some or all of the MPPT controller 1202 In certain embodiments, they are implemented in a common integrated circuit to favor small package size, small parasitic impedance between components, and fast signal transfer times. In these embodiments, the integrated circuit is optional with the photovoltaic device 1204 Packaged in a housing to minimize system size and minimum impedance between the device 1204 and the controller 1202 to favor. However, the MPPT controller is 1202 is not limited to an integrated circuit design and could instead be partially or fully formed from discrete components. The MPPT controller 1202 has at least two modes of operation, namely an MPPT mode of operation and a fixed duty cycle mode of operation. In MPPT operating mode, the control subsystem initiates 1238 the control switching device 1228 repeatedly toggling between its conductive and non-conductive states to at least substantially equal an amount from a photovoltaic device 1204 decoupled and to the load 1206 maximize delivered performance. For example, in some embodiments, the rule subsystem maximizes 1238 the power in the input terminal 1208 and thereby maximizes those from the photovoltaic device 1204 decoupled power. In some other embodiments, the rule subsystem maximizes 1238 the power from the output terminal 1214 What effectively removes the photovoltaic device 1204 decoupled power maximizes, as the power from the output port 1214 same as the power in the input terminal 1208 if you look at the losses in the MPPT controller 1202 neglected.

In fixed duty cycle mode, the control subsystem initiates 1238 the MPPT controller 1202 , a fixed DC transformation between the input and output terminals 1208 . 1214 to check the photovoltaic device 1204 or backward current operation in a similar manner as above with respect to the MPPT controller 302 ( 3 ). More specifically, the rule subsystem causes 1238 the control switching device 1228 to work at a fixed duty cycle to provide a fixed DC transformation between input terminal 1208 and output connection 1214 to reach. However, unlike the MPPT controller 302 the rule subsystem 1238 typically the free-running switching device 1230 instead of the control switching device 1228 to work at a high duty cycle, such as a duty cycle of at least ninety percent.

The rule subsystem 1238 is designed, for example, using one or more techniques similar to those above with respect to the MPPT controller 302 to determine when the regulator 1202 to operate in its fixed duty cycle mode, and when the regulator 1202 switch from its fixed duty cycle mode to MPPT mode. For example, the rule subsystem 1238 in some embodiments, in a similar manner to that described above 8th and 9 to determine that operation in fixed duty cycle mode is appropriate if voltage across the output terminal during startup 1214 is present, or if the output current Iout has a negative value. Another example is the rule subsystem 1238 in some embodiments, to exit the fixed duty cycle mode of operation after a predetermined period of time, or if the voltage across the input terminal 1208 below a threshold, in a similar way as above 10 and 11 described.

In down-boost topology applications, the control switching device operates in a fixed duty cycle operating mode at a fixed duty cycle, such as a fifty percent duty cycle, to achieve a fixed DC transformation.

The use of fixed duty cycle MPPT controllers is not limited to photovoltaic power generation systems with single photovoltaic device and single MPPT controller. For example 13 a photovoltaic power generation system 1300 represents the implementations of the MPPT controller 302 in a photovoltaic application, where N is an integer greater than one. This document may refer to certain implementations of an object by using a number in parentheses (eg, MPPT control 302 (1) ), While numbers without parentheses refer to any such item (eg MPPT controller) 302 ). Some of the building blocks of the MPPT controller 302 are in 13 not shown to favor a clear presentation.

The input connection 308 each MPPT controller 302 is to a respective photovoltaic device 1304 a common photovoltaic module 1305 electrically connected. photovoltaic devices 1304 are, for example, individual photovoltaic cells or groups of electrically interconnected photovoltaic cells. However, the arrangement of photovoltaic devices 1304 be varied without departing from the scope of the present For example, in some alternative embodiments, photovoltaic devices are 1304 discrete photovoltaic devices and are not part of a common module. In another example, in some other embodiments, two or more photovoltaic devices 1304 different arrangements. A respective input capacitor 1324 is also above each input terminal 308 electrically connected.

The output connections 314 the MPPT controller 302 are with a load 1306 electrically connected in series. One or more output capacitors 1334 are over the load 1306 are electrically connected and are from each of the N MPPT controllers 1302 shared. However, in some alternative embodiments, the load includes 1306 significant capacity, and the capacitors 1334 are therefore omitted. In addition, in some alternative embodiments, each MPPT controller 302 a respective capacitor (not shown) connected across its output terminal 314 electrically connected.

The MPPT controller 302 use the interconnect inductance 1336 an output circuit 1332 that the circuits 326 with the load 1306 electrically connects, as energy storage inductance. Although this interconnect inductance is shown symbolically as a single element, it is actually distributed along a loop that is the output circuit 1332 forms. However, some alternative embodiments include one or more discrete inductors (not shown) connected to the output circuit 1332 are electrically connected in series. For example, in embodiments where each MPPT controller is 302 a respective, above its output terminal 314 electrically connected capacitor typically requires that each MPPT regulator 302 a respective discrete inductance connected to its output terminal 314 electrically connected in series.

Each MPPT controller 302 operates in much the same way as described with respect to power generation systems including a single embodiment of the MPPT controller 302 contain. For example, in an MPPT mode of operation, each MPPT controller maximizes 302 the from his respective photovoltaic device 1304 decoupled power. In a fixed duty cycle mode, on the other hand, each MPPT controller operates so that its control switching device has a fixed duty cycle. For example, flash testing can be done by replacing the load 1306 by a variable load and passing through the load resistor while the photovoltaic devices 1304 a light source of known strength is exposed. EL testing can be done by replacing the load 1306 through a test current source and driving a test current into the output terminals 314 in a direction opposite to the normal output current Iout.

Operation in reverse current mode may have problems sharing power in applications with two or more MPPT controllers connected in parallel 302 prepare. For example 14 a photovoltaic power generation system 1400 that is, three parallel strings 1403 contains where each string contains three executions of the MPPT controller 302 with output terminals electrically connected in series 314 contains. A respective photovoltaic device 1404 is at the input port 308 every regulator 302 electrically connected. For clarity, only the input and output terminals 308 . 314 the regulator 302 shown.

Consider a scenario in which the string 1403 (1) produces a larger photogenerated current than either string 1403 (2) or 1403 (3) , such as partial shadowing of strings 1403 (2) . 1403 (3) , The forward current 1405 strong string 1403 (1) spans the weaker strings 1403 (2) . 1403 (3) in the forward direction, so that reverse currents 1407 . 1409 through the strings 1403 (2) respectively. 1403 (3) flow. If the strings 1403 (2) . 1403 (3) have the same current-voltage characteristics is the magnitude of the reverse currents 1407 . 1409 the same. If the strings 1403 (2) . 1403 (3) have different current-voltage characteristics, have the reverse currents 1407 . 1409 different amounts on, so the strings 1403 (2) . 1403 (3) do not divide the reverse flow equally.

The reverse current inequality may be due to the current-voltage characteristics of the photovoltaic devices 1404 be great. In particular, a photovoltaic cell has a similar current-voltage characteristic as a diode, as by the model of 1 which causes the cell voltage to be relatively insensitive to the amount of current as the cell conducts reverse current. Thus, any voltage imbalance that could exist between two discrete cells, when biased with the same amount of reverse current, can result in a large current imbalance when the cells are connected in parallel.

For example, shows 15 a curve 1500 the reverse current over the voltage for a photovoltaic cell 1502 , Suppose the cell 1502 work with a tension 1504 when with a reverse current 1506 is biased. Now suppose the cell 1502 be connected in parallel with another photovoltaic cell (not shown) with different current-voltage characteristic, so that the cell 1502 due to the parallel connection at the voltage 1508 Must work. The amount of reverse current jumps 1510 what a big change 1512 the amount of reverse current results to a small change 1514 the amount of voltage to compensate. Thus, small differences in the current-voltage characteristic between parallel-connected photovoltaic devices can cause significant reverse current imbalance in the devices.

Unequal splitting of the reverse current may cause a string to experience too high an amount of reverse current, which may be regulator 302 and / or photovoltaic devices 1404 of the string. There are also strings 1403 typically backed up for safety reasons, and too much of the reverse current in a string can blow the fuse of the string causing the string to be out of order and not generating power until the fuse is replaced.

Accordingly, certain embodiments of the MPPT controller are 302 designed to operate in a third mode of operation, sometimes referred to as a reverse current mode of operation, under reverse current conditions. In these embodiments, the rule subsystem is 338 designed, the control switching device 328 to repeatedly switch between its conductive and non-conductive states at a duty ratio that maintains a predetermined output current-voltage characteristic of the regulator as viewed from a load in the output terminal 314 , Operate each MPPT controller such that it has a common output-current-voltage characteristic allows each string to have a common output current-voltage characteristic, giving equal current sharing among the strings 1403 favors in reverse flow operation. The rule subsystem 308 causes the MPPT knob 302 enters the reverse current mode of operation when the magnitude of signal Io is, for example, less than or equal to a threshold, the threshold being negative or very low output current.

In some embodiments that support the reverse current mode of operation, the predetermined output current-voltage characteristic is linear, such that the magnitude of the average voltage across the output terminal 314 linear with a change in the average current in the output terminal 314 changes. 16 shows an example of a linear output current-voltage characteristic 1600 , In some other embodiments that support the reverse current mode of operation, the default output current-voltage characteristic is non-linear, such that the magnitude of the average voltage across the output terminal 314 non-linear with a change in the average current in the output terminal 314 changes. 17 shows an example of a non-linear output current-voltage characteristic 1700 ,

The fact that the characteristics 1600 . 1700 have relatively large effective resistances, ie the value of the voltage across the current, also favors the power distribution. In particular, the resistance of a string results in negative feedback because the resistor causes the string voltage to increase with the magnitude of the current, thereby reducing the amount of current needed to reach a given voltage. The nonlinear characteristic 1700 has a particularly large effective resistance for large amounts of current, possibly resulting in large negative feedback for large amounts of current. By contrast, a back-biased photovoltaic cell has a relatively small effective resistance, resulting in low negative feedback in parallel-connected applications.

A reverse current mode of operation is optionally in the MPPT controller 1202 ( 12 ) is implemented in a manner similar to the MPPT controller 302 ,

Combinations of features

• (A1) Ein Verfahren zum Betreiben eines Reglers für das Maximum Power Point Tracking (MPPT-Reglers), der einen Schaltkreis enthält, ausgelegt, Leistung zwischen einem Eingangsanschluss und einem Ausgangsanschluss zu übertragen, kann folgende Schritte enthalten: (a) in einem ersten Betriebsmodus des MPPT-Reglers Veranlassen einer ersten Schaltvorrichtung des Schaltkreises, bei einem festen Tastverhältnis zu arbeiten; und (b) in einem zweiten Betriebsmodus des MPPT-Reglers Veranlassen einer Regel-Schaltvorrichtung des Schaltkreises, wiederholt zwischen ihrem leitenden und nichtleitenden Zustand umzuschalten, um einen aus einer an den Eingangsanschluss elektrisch angeschlossenen Photovoltaikvorrichtung ausgekoppelten Betrag an Leistung zu maximieren.
• (A2) In dem als (A1) bezeichneten Verfahren kann die erste Schaltvorrichtung mindestens eins aus der Regel-Schaltvorrichtung des Schaltkreises und einer freilaufenden Schaltvorrichtung des Schaltkreises enthalten.
• (A3) In jedem der beiden als (A1) oder (A2) bezeichneten Verfahren kann das feste Tastverhältnis ein Tastverhältnis von mindestens neunzig Prozent sein.
• (A4) In jedem der beiden als (A1) oder (A2) bezeichneten Verfahren kann das feste Tastverhältnis ein Tastverhältnis von einhundert Prozent sein.
• (A5) Beliebige der als (A1) bis (A4) bezeichneten Verfahren können weiter enthalten: Betreiben des MPPT-Reglers in seinem ersten Betriebsmodus als Reaktion auf das Bestimmen vor dem Betrieb des Schaltkreises beim Anlauf des MPPT-Reglers, dass ein Betrag eines Signals, das die Spannung über dem Ausgangsanschluss darstellt, größer ist als ein erster Schwellwert.
• (A6) Beliebige der als (A1) bis (A5) bezeichneten Verfahren können weiter enthalten: Veranlassen des Schaltkreises, in seinem nichtleitenden Zustand zu arbeiten, bis ein Betrag einer Spannung auf einer Stromversorgungsschiene des MPPT-Reglers einen vorgegebenen Wert überschreitet.
• (A7) Das als (A6) bezeichnete Verfahren kann weiter enthalten: im ersten Betriebsmodus des MPPT-Reglers Versorgen der Stromversorgungsschiene des MPPT-Reglers vom Ausgangsanschluss her.
• (A8) in dem als (A7) bezeichneten Verfahren kann die erste Schaltvorrichtung einen ersten Transistor enthalten, und das Verfahren kann elektrisches Einspeisen von Strom in die Stromversorgungsschiene des MPPT-Reglers unter Verwendung einer Bodydiode des ersten Transistors enthalten.
• (A9) Beliebige der als (A1) bis (A8) bezeichneten Verfahren können weiter enthalten: Betreiben des MPPT-Reglers in seinem ersten Betriebsmodus als Reaktion auf das Bestimmen, dass ein Signal, das aus dem Ausgangsanschluss fließenden Strom darstellt, niedriger als ein oder gleich einem zweiten Schwellwert ist.
• (A10) In dem als (A9) bezeichneten Verfahren kann der zweite Schwellwert darstellen, dass Strom aus dem Ausgangsanschluss in einer negativen Richtung fließt.
• (A11) Weiter kann das als (A10) bezeichnete Verfahren Weiterbetreiben des MPPT-Reglers in seinem ersten Betriebsmodus enthalten, nachdem ein Betrag aus dem Ausgangsanschluss fließenden Stroms auf null gefallen ist.
• (A12) Beliebige der als (A1) bis (A11) bezeichneten Verfahren können weiter enthalten: Betreiben des MPPT-Reglers in seinem ersten Betriebsmodus als Reaktion auf ein externes Signal.
• (A13) Beliebige der als (A1) bis (A12) bezeichneten Verfahren können weiter enthalten: Betreiben des MPPT-Reglers in seinem ersten Betriebsmodus jedes Mal, wenn der MPPT-Regler anläuft.
• (A14) Beliebige der als (A1) bis (A13) bezeichneten Verfahren können weiter enthalten: Veranlassen, dass ein Tastverhältnis der ersten Schaltvorrichtung zum festen Tastverhältnis hochläuft, wenn der MPPT-Regler beginnt, in seinem ersten Betriebsmodus zu arbeiten.
• (A15) Beliebige der als (A1) bis (A14) bezeichneten Verfahren können weiter enthalten: Schalten vom ersten Betriebsmodus zu einem anderen Betriebsmodus des MPPT-Reglers nach einem vorgegebenen Zeitraum.
• (A16) Beliebige der als (A1) bis (A15) bezeichneten Verfahren können weiter enthalten: Schalten vom ersten Betriebsmodus zu einem anderen Betriebsmodus des MPPT-Reglers, wenn ein erstes Spannungssignal unter einen dritten Schwellwert fällt.
• (A17) In dem als (A16) bezeichneten Verfahren kann das erste Spannungssignal eine Funktion einer Spannung über dem Eingangsanschluss sein.
• (A18) In jedem der als (A15) bis (A17) bezeichneten Verfahren kann der andere Betriebsmodus der zweite Betriebsmodus des MPPT-Reglers sein.
• (A19) Beliebige der als (A1) bis (A18) bezeichneten Verfahren können weiter enthalten: Veranlassen der Regel-Schaltvorrichtung, in einem dritten Betriebsmodus des MPPT-Reglers wiederholt zwischen ihrem leitenden und nichtleitenden Zustand bei einem Tastverhältnis umzuschalten, das eine vorgegebene Ausgangs-Strom-Spannungs-Kennlinie des MPPT-Reglers beibehält.
• (A20) Das als (A19) bezeichnete Verfahren kann weiter enthalten: Betreiben des MPPT-Reglers in seinem dritten Betriebsmodus als Reaktion auf das Bestimmen, dass ein Signal, das aus dem Ausgangsanschluss fließenden Strom darstellet, niedriger als ein oder gleich einem vierten Schwellwert ist, wobei der vierte Schwellwert darstellen kann, dass Strom aus dem Ausgangsanschluss in einer negativen Richtung fließt.
• (A21) In jedem der beiden als (A19) und (A20) bezeichneten Verfahren kann die vorgegebene Ausgangs-Strom-Spannungs-Kennlinie des MPPT-Reglers linear sein, sodass sich der Betrag der mittleren Spannung über dem Ausgangsanschluss linear mit einer Änderung des Betrags eines in den Eingangsanschluss fließenden mittleren Stroms ändert.
• (A22) In jedem der beiden als (A19) und (A20) bezeichneten Verfahren kann die vorgegebene Ausgangs-Strom-Spannungs-Kennlinie des MPPT-Reglers nichtlinear sein, sodass sich der Betrag der mittleren Spannung über dem Ausgangsanschluss nichtlinear mit einer Änderung des Betrags eines in den Eingangsanschluss fließenden mittleren Stroms ändert.
• (B1) Ein Verfahren zum Prüfen einer mit einem Eingangsanschluss eines Reglers für das Maximum Power Point Tracking (MPPT-Reglers) elektrisch verbundenen Photovoltaikvorrichtung, wobei der MPPT-Regler einen Schaltkreis enthält, ausgelegt, Leistung zwischen dem Eingangsanschluss und einem Ausgangsanschluss des MPPT-Reglers zu übertragen, kann folgende Schritte enthalten: (a) Treiben eines Prüfstroms in den Ausgangsanschluss des MPPT-Reglers; (b) Erkennen des Vorhandenseins des Prüfstroms; und (c) als Reaktion auf das Erkennen des Vorhandenseins des Prüfstroms Veranlassen des Schaltkreises, einen Weg für den Prüfstrom vom Ausgangsanschluss zur Photovoltaikvorrichtung vorzusehen.
• (B2) In dem als (B1) bezeichneten Verfahren kann der Schritt des Veranlassens des Schaltkreises, einen Weg für den Prüfstrom vom Ausgangsanschluss zur Photovoltaikvorrichtung vorzusehen, das Veranlassen einer Schaltvorrichtung des Schaltkreises enthalten, bei einem festen Tastverhältnis zu arbeiten.
• (B3) In dem als (B2) bezeichneten Verfahren kann das feste Tastverhältnis ein Tastverhältnis von mindestens neunzig Prozent sein.
• (B4) In dem als (B2) bezeichneten Verfahren kann das feste Tastverhältnis ein Tastverhältnis von einhundert Prozent sein.
• (B5) In jedem der als (B1) bis (B4) bezeichneten Verfahren kann der Schritt des Veranlassens des Schaltkreises, einen Weg für den Prüfstrom vom Ausgangsanschluss zur Photovoltaikvorrichtung vorzusehen, das Veranlassen des MPPT-Reglers enthalten, als fester Gleichstromtransformator zu wirken, der den Prüfstrom mit der Photovoltaikvorrichtung elektrisch verbindet.
• (B6) In jedem der als (B1) bis (B5) bezeichneten Verfahren kann der Schritt des Erkennens des Vorhandenseins des Prüfstroms das Erkennen des Vorhandenseins von Strom enthalten, der von einer externen Quelle in den Ausgangsanschluss fließt.
• (B7) In jedem der als (B1) bis (B6) bezeichneten Verfahren kann der Schritt des Erkennens des Vorhandenseins des Prüfstroms das Erkennen von Spannung über dem Ausgangsanschluss des Schaltkreises enthalten.
• (B8) In dem als (B7) bezeichneten Verfahren kann der Schritt des Erkennens von Spannung über dem Ausgangsanschluss des Schaltkreises das Vergleichen eines Signals, das die Spannung über dem Ausgangsanschluss darstellt, mit einem Schwellwert enthalten.
• (C1) Ein Regler für das Maximum Power Point Tracking (MPPT-Regler) kann einen Eingangs- und einen Ausgangsanschluss, einen Schaltkreis, ausgelegt, Leistung zwischen dem Eingangs- und dem Ausgangsanschluss zu übertragen, und ein Regel-Untersystem enthalten. Das Regel-Untersystem kann ausgelegt sein, (a) in einem ersten Betriebsmodus des MPPT-Reglers eine erste Schaltvorrichtung des Schaltkreises zu veranlassen, bei einem festen Tastverhältnis zu arbeiten; und (b) in einem zweiten Betriebsmodus des MPPT-Reglers eine Regel-Schaltvorrichtung des Schaltkreises zu veranlassen, wiederholt zwischen ihrem leitenden und nichtleitenden Zustand umzuschalten, um einen aus einer an den Eingangsanschluss elektrisch angeschlossenen Photovoltaikvorrichtung ausgekoppelten Betrag an elektrischer Leistung zu maximieren.
• (C2) In dem als (C1) bezeichneten MPPT-Regler kann die erste Schaltvorrichtung mindestens eins aus der Regel-Schaltvorrichtung des Schaltkreises und einer freilaufenden Schaltvorrichtung des Schaltkreises enthalten.
• (C3) In jedem der beiden als (C1) oder (C2) bezeichneten MPPT-Regler kann das feste Tastverhältnis ein Tastverhältnis von mindestens neunzig Prozent sein.
• (C4) In jedem der beiden als (C1) oder (C2) bezeichneten MPPT-Regler kann das feste Tastverhältnis ein Tastverhältnis von einhundert Prozent sein.
• (C5) In jedem der als (C1) bis (C4) bezeichneten MPPT-Regler kann das Regel-Untersystem weiter ausgelegt sein: (a) vor dem Betrieb des Schaltkreises beim Anlauf des MPPT-Reglers einen Betrag eines Signals, das die Spannung über dem Ausgangsanschluss darstellt, mit einem ersten Schwellwert zu vergleichen; und (b) den MPPT-Regler in seinem ersten Betriebsmodus zu betreiben als Reaktion auf das Bestimmen, dass der Betrag des Signals, das Spannung über dem Ausgangsanschluss darstellt, größer ist als der erste Schwellwert.
• (C6) In jedem der als (C1) bis (C5) bezeichneten MPPT-Regler kann das Regel-Untersystem weiter ausgelegt sein, den Schaltkreis zu veranlassen, in seinem nichtleitenden Zustand zu arbeiten, bis ein Betrag einer Spannung auf einer Stromversorgungsschiene des MPPT-Reglers einen vorgegebenen Wert überschreitet.
• (C7) In dem als (C6) bezeichneten MPPT-Regler kann der MPPT-Regler weiter so ausgelegt sein, dass im ersten Betriebsmodus des MPPT-Reglers die Stromversorgungsschiene des MPPT-Reglers vom Ausgangsanschluss her versorgt ist.
• (C8) In jedem der als (C1) bis (C7) bezeichneten MPPT-Regler: (a) kann die Regel-Schaltvorrichtung zwischen einer ersten Klemme des Eingangsanschlusses und einer ersten Klemme des Ausgangsanschlusses elektrisch verbunden sein; (b) kann der Schaltkreis weiter eine freilaufende Vorrichtung enthalten, die zwischen der ersten Klemme des Ausgangsanschlusses und einer zweiten Klemme des Ausgangsanschlusses elektrisch verbunden ist, wobei die freilaufende Vorrichtung ausgelegt ist, einen Weg für zwischen der ersten und der zweiten Klemme des Ausgangsanschlusses fließenden Strom vorzusehen, wenn sich die Regel-Schaltvorrichtung in ihrem nichtleitenden Zustand befindet; (c) kann die erste Schaltvorrichtungen die Regel-Schaltvorrichtung sein; und (d) kann die erste Klemme des Ausgangsanschlusses mit einem Schaltknoten elektrisch verbunden sein.
• (C9) In dem als (C8) bezeichneten MPPT-Regler kann die Regel-Schaltvorrichtung ein Regel-Transistor sein, wobei der Regel-Transistor eine Bodydiode mit einer mit dem Schaltknoten elektrisch verbundenen Anode und einer mit der ersten Klemme des Eingangsanschlusses verbundenen Kathode enthält.
• (C10) In jedem der als (C1) bis (C9) bezeichneten MPPT-Regler kann das Regel-Untersystem weiter ausgelegt sein: (a) ein Signal, das aus dem Ausgangsanschluss fließenden Strom darstellt, mit einem zweiten Schwellwert zu vergleichen; und (b) den MPPT-Regler in seinem ersten Betriebsmodus zu betreiben als Reaktion auf das Bestimmen, dass das Signal, das aus dem Ausgangsanschluss fließenden Strom darstellt, niedriger als der oder gleich dem zweiten Schwellwert ist.
• (C11) In dem als (C10) bezeichneten Verfahren kann der zweite Schwellwert darstellen, dass Strom aus dem Ausgangsanschluss in einer negativen Richtung fließt.
• (C12) In dem als (C11) bezeichneten MPPT-Regler kann das Regel-Untersystem weiter ausgelegt sein, den MPPT-Regler weiter in seinem ersten Betriebsmodus zu betreiben, nachdem ein Betrag aus dem Ausgangsanschluss fließenden Stroms auf null gefallen ist.
• (C13) In jedem der als (C1) bis (C12) bezeichneten MPPT-Regler kann das Regel-Untersystem weiter ausgelegt sein, den MPPT-Regler als Reaktion auf ein externes Signal in seinem ersten Betriebsmodus zu betreiben.
• (C14) In jedem der als (C1) bis (C13) bezeichneten MPPT-Regler kann das Regel-Untersystem weiter ausgelegt sein, den MPPT-Regler jedes Mal, wenn der MPPT-Regler anläuft, in seinem ersten Betriebsmodus zu betreiben.
• (C15) In jedem der als (C1) bis (C14) bezeichneten MPPT-Regler kann das Regel-Untersystem weiter ausgelegt sein zu veranlassen, dass ein Tastverhältnis der ersten Schaltvorrichtung zum festen Tastverhältnis hochläuft, wenn der MPPT-Regler beginnt, in seinem ersten Betriebsmodus zu arbeiten.
• (C16) In jedem der als (C1) bis (C15) bezeichneten MPPT-Regler kann das Regel-Untersystem weiter ausgelegt sein, den MPPT-Regler zu veranlassen, nach einem vorgegebenen Zeitraum von seinem ersten Betriebsmodus zu einem anderen Betriebsmodus umzuschalten.
• (C17) In jedem der als (C1) bis (C16) bezeichneten MPPT-Regler kann das Regel-Untersystem weiter ausgelegt sein: (a) ein erstes Spannungssignal mit einem dritten Schwellwert zu vergleichen, wobei das erste Spannungssignal eine Funktion einer Spannung über dem Eingangsanschluss ist; und (b) den MPPT-Regler zu veranlassen, von seinem ersten Betriebsmodus zu einem anderen Betriebsmodus des MPPT-Reglers umzuschalten, wenn das erste Spannungssignal unter den dritten Schwellwert fällt.
• (C18) In jedem der beiden als (C16) oder (C17) bezeichneten Verfahren kann der andere Betriebsmodus der zweite Betriebsmodus des MPPT-Reglers sein.
• (C19) In jedem der als (C1) bis (C18) bezeichneten MPPT-Regler kann das Regel-Untersystem weiter ausgelegt sein, die Regel-Schaltvorrichtung zu veranlassen, in einem dritten Betriebsmodus des MPPT-Reglers wiederholt zwischen ihrem leitenden und nichtleitenden Zustand bei einem Tastverhältnis umzuschalten, das eine vorgegebene Ausgangs-Strom-Spannungs-Kennlinie des MPPT-Reglers beibehält.
• (C20) In dem als (C19) bezeichneten MPPT-Regler kann das Regel-Untersystem weiter ausgelegt sein: (a) ein Signal, das aus dem Ausgangsanschluss fließenden Strom darstellt, mit einem vierten Schwellwert zu vergleichen; und (b) den MPPT-Regler in seinem dritten Betriebsmodus zu betreiben als Reaktion auf das Bestimmen, dass das Signal, das aus dem Ausgangsanschluss fließenden Strom darstellt, niedriger als der oder gleich dem vierten Schwellwert ist.
• (C21) In dem als (C20) bezeichneten MPPT-Regler kann der vierte Schwellwert darstellen, dass Strom aus dem Ausgangsanschluss in einer negativen Richtung fließt.
• (C22) In jedem der als (C19) bis (C21) bezeichneten MPPT-Regler kann die vorgegebene Ausgangs-Strom-Spannungs-Kennlinie des MPPT-Reglers linear sein, sodass sich der Betrag der mittleren Spannung über dem Ausgangsanschluss linear mit einer Änderung des Betrags eines in den Eingangsanschluss fließenden mittleren Stroms ändert.
• (C23) In jedem der als (C19) bis (C21) bezeichneten MPPT-Regler kann die vorgegebene Ausgangs-Strom-Spannungs-Kennlinie des MPPT-Reglers nichtlinear sein, sodass sich der Betrag der mittleren Spannung über dem Ausgangsanschluss nichtlinear mit einer Änderung des Betrags eines in den Eingangsanschluss fließenden mittleren Stroms ändert.

The features described above and the features claimed below can be combined in various ways without deviating from the present scope. The following examples are some possible combinations.

• (A1) A method of operating a maximum power point tracking (MPPT) controller including a circuit configured to transfer power between an input terminal and an output terminal may include the following steps: (a) in a first mode of operation the MPPT controller causing a first switching device of the circuit to operate at a fixed duty cycle; and (b) in a second mode of operation of the MPPT controller, causing a control switching device of the circuit to repeatedly switch between its conducting and non-conducting states to maximize an amount of power coupled out of a photovoltaic device electrically coupled to the input port.
• (A2) In the method referred to as (A1), the first switching device may include at least one of the control switching device of the switching circuit and a free-running switching device of the switching circuit.
• (A3) In either of the two methods (A1) or (A2), the fixed duty cycle may be a duty cycle of at least ninety percent.
• (A4) In either of the two methods (A1) or (A2), the fixed duty cycle may be a duty cycle of one hundred percent.
• (A5) Any of the methods referred to as (A1) to (A4) may further include: operating the MPPT controller in its first mode of operation in response to determining before operation of the circuit during start-up of the MPPT controller that an amount of a signal representing the voltage across the output terminal is greater than a first threshold.
• (A6) Any of the methods referred to as (A1) to (A5) may further include: causing the circuit to operate in its non-conductive state until an amount of voltage on a power rail of the MPPT controller exceeds a predetermined value.
• (A7) The procedure referred to as (A6) may further include: in the first operating mode of the MPPT controller, supplying the power supply rail of the MPPT controller from the output terminal.
• (A8) In the method referred to as (A7), the first switching device may include a first transistor, and the method may include electrically feeding current to the power rail of the MPPT controller using a body diode of the first transistor.
• (A9) Any of the methods referred to as (A1) to (A8) may further include: operating the MPPT controller in its first mode of operation in response to determining that a signal representing current flowing out of the output terminal is lower than or is equal to a second threshold.
• (A10) In the method referred to as (A9), the second threshold may represent that current flows from the output terminal in a negative direction.
• (A11) Further, the method referred to as (A10) may include further driving the MPPT controller in its first operation mode after an amount of current flowing out of the output terminal has dropped to zero.
• (A12) Any of the methods referred to as (A1) to (A11) may further include: operating the MPPT controller in its first mode of operation in response to an external signal.
• (A13) Any of the methods referred to as (A1) to (A12) may further include: operating the MPPT controller in its first mode of operation each time the MPPT controller starts up.
• (A14) Any of the methods referred to as (A1) to (A13) may further include: causing a duty cycle of the first fixed duty switching device to ramp up when the MPPT controller starts to operate in its first mode of operation.
• (A15) Any of the methods referred to as (A1) to (A14) may further include: switching from the first operation mode to another operation mode of the MPPT controller after a predetermined period of time.
• (A16) Any of the methods referred to as (A1) to (A15) may further include: switching from the first mode of operation to another mode of operation of the MPPT controller when a first voltage signal falls below a third threshold.
• (A17) In the method referred to as (A16), the first voltage signal may be a function of a voltage across the input terminal.
• (A18) In each of the methods referred to as (A15) to (A17), the other operating mode may be the second operating mode of the MPPT controller.
• (A19) Any of the methods referred to as (A1) to (A18) may further include: causing the control switching device to repeatedly switch between its conducting and non-conducting states at a duty cycle in a third mode of operation of the MPPT controller which is a predetermined output Maintains the current-voltage characteristic of the MPPT controller.
• (A20) The method referred to as (A19) may further include: operating the MPPT controller in its third mode of operation in response to determining that a signal representing current flowing out of the output terminal is less than or equal to a fourth threshold wherein the fourth threshold may represent that current flows from the output terminal in a negative direction.
• (A21) In either of the two methods (A19) and (A20), the predetermined output-current-voltage characteristic of the MPPT controller may be linear, so that the amount of average voltage across the output terminal becomes linear with a change in magnitude a mean current flowing in the input terminal changes.
• (A22) In either of the two methods (A19) and (A20), the predetermined output current-voltage characteristic of the MPPT controller may be non-linear, so that the amount of the average voltage across the output terminal is non-linear with a change in magnitude a mean current flowing in the input terminal changes.
• (B1) A method of testing a photovoltaic device electrically connected to an input port of a Maximum Power Point Tracking (MPPT) controller, the MPPT controller comprising a circuit configured to output power between the input port and an output port of the MPPT controller may include the steps of: (a) driving a test current into the output terminal of the MPPT controller; (b) detecting the presence of the test current; and (c) in response to detecting the presence of the test current, causing the circuit to provide a path for the test current from the output terminal to the photovoltaic device.
• (B2) In the method referred to as (B1), the step of causing the circuit to provide a path for the test current from the output terminal to the photovoltaic device may include causing a switching device of the circuit to operate at a fixed duty ratio.
• (B3) In the method referred to as (B2), the fixed duty cycle may be a duty cycle of at least ninety percent.
• (B4) In the method referred to as (B2), the fixed duty ratio may be a duty factor of one hundred percent.
• (B5) In each of the methods referred to as (B1) to (B4), the step of causing the circuit to provide a path for the test current from the output terminal to the photovoltaic device may include causing the MPPT controller to act as a fixed DC transformer electrically connects the test current to the photovoltaic device.
• (B6) In each of the methods referred to as (B1) to (B5), the step of detecting the presence of the test current may include detecting the presence of current flowing into the output terminal from an external source.
• (B7) In each of the methods referred to as (B1) to (B6), the step of detecting the presence of the test current may include detecting voltage across the output terminal of the circuit.
• (B8) In the method referred to as (B7), the step of detecting voltage across the output terminal of the circuit may include comparing a signal representing the voltage across the output terminal with a threshold value.
• (C1) A Maximum Power Point Tracking (MPPT) controller can provide an input and output port, a circuit designed to transfer power between the input and output ports, and a control subsystem. The control subsystem may be configured to: (a) cause, in a first mode of operation of the MPPT controller, a first switching device of the circuit to operate at a fixed duty cycle; and (b) in a second mode of operation of the MPPT controller, causing a control switching device of the circuit to repeatedly switch between its conducting and non-conducting states to maximize an amount of electrical power coupled out of a photovoltaic device electrically connected to the input port.
• (C2) In the MPPT controller (C1), the first switching device may include at least one of the control switching device of the switching circuit and a free-running switching device of the switching circuit.
• (C3) In each of the two (C1) or (C2) MPPT controllers, the fixed duty cycle may be a duty cycle of at least ninety percent.
• (C4) In each of the two MPPT controllers (C1) or (C2), the fixed duty cycle can be a duty cycle of one hundred percent.
• (C5) In each of the MPPT controllers denoted as (C1) to (C4), the control subsystem may be further configured: (a) before operation of the circuit during start-up of the MPPT controller, an amount of a signal exceeding the voltage the output port is to compare with a first threshold; and (b) operate the MPPT controller in its first mode of operation in response to determining that the magnitude of the signal representing voltage across the output terminal is greater than the first threshold.
• (C6) In each of the MPPT controllers labeled (C1) through (C5), the control subsystem may be further configured to cause the circuit to operate in its non-conductive state until an amount of voltage is applied to a power rail of the MPPT controller. Controller exceeds a predetermined value.
• (C7) In the MPPT controller labeled (C6), the MPPT controller can be further designed so that in the first operating mode of the MPPT controller, the power rail of the MPPT controller is powered from the output terminal.
• (C8) In each of the MPPT controllers denoted as (C1) to (C7): (a) the control switching device may be electrically connected between a first terminal of the input terminal and a first terminal of the output terminal; (b) the circuit may further include a free-wheeling device electrically connected between the first terminal of the output terminal and a second terminal of the output terminal, the free-wheeling device configured to provide a path for current flowing between the first and second terminals of the output terminal provided when the control switching device is in its non-conductive state; (c) the first switching device may be the regulation switching device; and (d) the first terminal of the output terminal may be electrically connected to a switching node.
• (C9) In the MPPT controller (C8), the control switching device may be a regulation transistor, the regulation transistor including a body diode having an anode electrically connected to the switching node and a cathode connected to the first terminal of the input terminal ,
• (C10) In each of the MPPT controllers labeled (C1) to (C9), the control subsystem may be further configured to: (a) compare a signal representing current flowing from the output terminal with a second threshold value; and (b) operate the MPPT controller in its first mode of operation in response to determining that the signal representing current flowing out of the output terminal is lower than or equal to the second threshold.
• (C11) In the method referred to as (C10), the second threshold may represent that current flows from the output terminal in a negative direction.
• (C12) In the MPPT controller (C11), the control subsystem may be further configured to continue operating the MPPT controller in its first mode of operation after an amount of current flowing out of the output terminal has dropped to zero.
• (C13) In each of the MPPT controllers labeled (C1) to (C12), the control subsystem may be further configured to operate the MPPT controller in response to an external signal in its first mode of operation.
• (C14) In each of the MPPT controllers labeled (C1) to (C13), the control subsystem may be further configured to operate the MPPT controller in its first mode of operation each time the MPPT controller is started up.
• (C15) In each of the MPPT controllers denoted as (C1) to (C14), the control subsystem may be further configured to cause a duty cycle of the first duty factor switching device to ramp up when the MPPT controller starts, in its first Operating mode to work.
• (C16) In each of the MPPT controllers labeled (C1) through (C15), the control subsystem may be further configured to cause the MPPT controller to switch from its first mode of operation to another mode of operation after a predetermined period of time.
• (C17) In each of the MPPT controllers labeled (C1) to (C16), the control subsystem may be further configured to: (a) compare a first voltage signal to a third threshold, the first voltage signal being a function of a voltage across the Input terminal is; and (b) cause the MPPT controller to switch from its first mode of operation to another mode of operation of the MPPT controller when the first voltage signal falls below the third threshold.
• (C18) In either of the two methods (C16) or (C17), the other mode of operation may be the second mode of operation of the MPPT controller.
• (C19) In each of the MPPT controllers labeled (C1) through (C18), the control subsystem may be further configured to cause the control switching device to repeatedly switch between its conductive and non-conductive states in a third mode of operation of the MPPT controller switch a duty cycle, which maintains a predetermined output current-voltage characteristic of the MPPT controller.
• (C20) In the MPPT controller (C19), the control subsystem may be further configured to: (a) compare a signal representing current flowing from the output terminal with a fourth threshold value; and (b) operate the MPPT controller in its third mode of operation in response to determining that the signal representing current flowing out of the output terminal is less than or equal to the fourth threshold.
• (C21) In the MPPT controller (C20), the fourth threshold may represent that current flows from the output terminal in a negative direction.
• (C22) In each MPPT controller labeled (C19) to (C21), the default output current-voltage characteristic of the MPPT controller may be linear such that the magnitude of the average voltage across the output terminal is linear with a change in MPPT Amount of flowing in the input terminal medium current changes.
• (C23) In each MPPT controller labeled (C19) to (C21), the default output current-voltage characteristic of the MPPT controller may be non-linear, such that the magnitude of the average voltage across the output terminal is non-linear with a change in MPPT Amount of flowing in the input terminal medium current changes.

Changes may be made to the above methods and systems without departing from the present scope. For example, with appropriate changes to the associated circuitry, N-channel field effect transistors could be replaced by P-channel field effect transistors or vice versa. As another example, with appropriate changes to the associated circuit, field effect transistors could be replaced by bipolar junction transistors. It is therefore to be understood that the matter contained in the above description and shown in the accompanying drawings should be interpreted as illustrative and not in a limiting sense. The following claims are intended to cover generic and specific features described herein, as well as all statements regarding the scope of the present method and system that could linguistically be said to fall in between.

Claims (63)

A method of operating a maximum power point tracking (MPPT) controller including a circuit configured to transfer power between an input port and an output port, comprising the steps of: in a first mode of operation of the MPPT controller, causing a first switching device of the circuit to operate at a fixed duty cycle; and in a second mode of operation of the MPPT controller, causing a control switching device of the circuit to repeatedly switch between its conductive and non-conductive states to maximize an amount of power coupled out of a photovoltaic device electrically coupled to the input terminal. The method of claim 1, wherein the first switching device includes at least one of the control switching device of the circuit and a free-running switching device of the circuit.  The method of claim 2, wherein the fixed duty cycle is a duty cycle of at least ninety percent.  The method of claim 3, wherein the fixed duty cycle is a duty cycle of one hundred percent.  The method of claim 2, further comprising operating the MPPT controller in its first mode of operation in response to determining prior to operation of the circuit during start-up of the MPPT controller that an amount of a signal representing the voltage across the output terminal is greater as a threshold.  The method of claim 5, further comprising causing the circuit to operate in its non-conductive state until an amount of voltage on a power rail of the MPPT controller exceeds a predetermined value.  The method of claim 6, further comprising, in the first mode of operation of the MPPT controller, providing the power supply rail of the MPPT controller from the output port.  The method of claim 7, wherein the first switching device includes a first transistor, and the method further includes electrically feeding power to the power rail of the MPPT controller using a body diode of the first transistor.  The method of claim 2, further comprising operating the MPPT controller in its first mode of operation in response to determining that a signal representing current flowing out of the output terminal is less than or equal to a threshold.  The method of claim 9, wherein the threshold represents that current flows from the output terminal in a negative direction.  The method of claim 10, further comprising causing the circuit to operate in its non-conducting state until an amount of voltage on a power rail of the MPPT controller exceeds a predetermined value.  The method of claim 11, further comprising, in the first mode of operation of the MPPT controller, providing the power supply rail of the MPPT controller from the output port.  The method of claim 12, wherein the first switching device includes a first transistor and the method includes electrically injecting current into the power rail of the MPPT controller using a body diode of the first transistor.  The method of claim 10, further comprising continuing the MPPT controller in its first mode of operation after an amount of current flowing out of the output terminal has dropped to zero.  The method of claim 2, further comprising operating the MPPT controller in its first mode of operation in response to an external signal.  The method of claim 2, further comprising operating the MPPT controller in its first mode of operation each time the MPPT controller starts up.  The method of claim 2, further comprising causing a duty cycle of the first fixed duty cycle switching device to start up when the MPPT controller begins to operate in its first mode of operation.  The method of claim 2, further comprising switching from the first mode of operation to another mode of operation of the MPPT controller after a predetermined period of time. The method of claim 18, wherein the other mode of operation is the second mode of operation of the MPPT controller.  The method of claim 2, further comprising switching from the first mode of operation to another mode of operation of the MPPT controller when a first voltage signal falls below a threshold.  The method of claim 20, wherein the first voltage signal is a function of a voltage across the input terminal.  The method of claim 20, wherein the other mode of operation is the second mode of operation of the MPPT controller.  The method of claim 2, further comprising causing the control switching device to repeatedly switch between its conductive and non-conductive states at a duty cycle that maintains a predetermined output-current-voltage characteristic of the MPPT controller in a third mode of operation of the MPPT controller.  The method of claim 23, further comprising operating the MPPT controller in its third mode of operation in response to determining that a signal representing current flowing out of the output terminal is less than or equal to a threshold.  The method of claim 24, wherein the threshold represents that current flows from the output terminal in a negative direction.  The method of claim 23, wherein the predetermined output-current-voltage characteristic of the MPPT controller is linear such that the magnitude of the average voltage across the output terminal varies linearly with a change in the amount of average current flowing into the input terminal.  The method of claim 23, wherein the predetermined output-current-voltage characteristic of the MPPT controller is non-linear such that the magnitude of the average voltage across the output terminal varies non-linearly with a change in the amount of average current flowing into the input terminal.  A method of testing a photovoltaic device electrically connected to an input port of a Maximum Power Point Tracking (MPPT) controller, the MPPT controller including a circuit configured to transfer power between the input port and an output port of the MPPT controller, wherein the method comprises the following steps: Driving a test current into the output terminal of the MPPT controller; Detecting the presence of the test current; and in response to detecting the presence of the test current, causing the circuit to provide a path for the test current from the output terminal to the photovoltaic device.  The method of claim 28, wherein the step of causing the circuit to provide a path for the test current from the output terminal to the photovoltaic device comprises causing a switching device of the circuit to operate at a fixed duty cycle.  The method of claim 29, wherein the fixed duty cycle is a duty cycle of at least ninety percent.  The method of claim 30, wherein the fixed duty cycle is a duty cycle of one hundred percent.  The method of claim 28, wherein the step of causing the circuit to provide a path for the test current from the output terminal to the photovoltaic device, comprises causing the MPPT controller to act as a fixed dc transformer electrically connecting the test current to the photovoltaic device. The method of claim 28, wherein the step of detecting the presence of the test current comprises detecting the presence of current flowing into the output terminal from an external source.  The method of claim 28, wherein the step of detecting the presence of the test current comprises detecting voltage across the output terminal of the circuit.  The method of claim 34, wherein the step of detecting voltage across the output terminal of the circuit comprises comparing a signal representing the voltage across the output terminal with a threshold.  Maximum Power Point Tracking (MPPT) controller, comprising: an input and an output terminal; a circuit configured to transfer power between the input and output terminals; and a rule subsystem, designed: in a first mode of operation of the MPPT controller, causing a first switching device of the circuit to operate at a fixed duty cycle, and in a second mode of operation of the MPPT controller, causing a control switching device of the circuit to repeatedly switch between its conductive and non-conductive states to maximize an amount of electrical power coupled out of a photovoltaic device electrically coupled to the input terminal.  The MPPT controller of claim 36, wherein the first switching device includes at least one of the control switching device of the circuit and a free-running switching device of the circuit.  The MPPT controller of claim 37, wherein the fixed duty cycle is a duty cycle of at least ninety percent.  The MPPT controller of claim 38, wherein the fixed duty cycle is a duty cycle of one hundred percent.  The MPPT controller of claim 37, wherein the rule subsystem is further configured: prior to operation of the circuit during start-up of the MPPT controller, comparing an amount of a signal representing the voltage across the output terminal with a threshold; and operate the MPPT controller in its first mode of operation in response to determining that the magnitude of the signal representing voltage across the output terminal is greater than the threshold.  The MPPT controller of claim 40, wherein the control subsystem is further configured to cause the circuit to operate in its non-conducting state until an amount of voltage on a power rail of the MPPT controller exceeds a predetermined value.  The MPPT controller of claim 41, wherein the MPPT controller is further configured such that in the first mode of operation of the MPPT controller, the power rail of the MPPT controller is powered from the output port.  The MPPT controller of claim 41, wherein the control switching device is electrically connected between a first terminal of the input terminal and a first terminal of the output terminal; the circuit further comprises a free-wheeling device electrically connected between the first terminal of the output terminal and a second terminal of the output terminal, the free-wheeling device configured to provide a path for current flowing between the first and second terminals of the output terminal when the control switching device is in its non-conducting state; the first switching device is the control switching device; and the first terminal of the output terminal is electrically connected to a switching node.  The MPPT controller of claim 43, wherein the control switching device comprises a control transistor, the control transistor including a body diode having an anode electrically connected to the switching node and a cathode connected to the first terminal of the input terminal. The MPPT controller of claim 37, wherein the rule subsystem is further configured: compare a signal representing current flowing from the output terminal with a threshold value; and operate the MPPT controller in its first mode of operation in response to determining that the signal representing current flowing out of the output terminal is less than or equal to the threshold.  The MPPT controller of claim 45, wherein the threshold represents that current flows from the output terminal in a negative direction.  The MPPT controller of claim 46, wherein the control subsystem is further configured to cause the circuit to operate in its non-conductive state until an amount of voltage on a power rail of the MPPT controller exceeds a predetermined value.  The MPPT controller of claim 47, wherein the MPPT controller is configured such that in the first mode of operation of the MPPT controller, the power rail of the MPPT controller is powered from the output port.  The MPPT controller of claim 47, wherein the control switching device is electrically connected between a first terminal of the input terminal and a first terminal of the output terminal; the circuit further comprises a free-wheeling device electrically connected between the first terminal of the output terminal and a second terminal of the output terminal, the free-wheeling device configured to provide a path for current flowing between the first and second terminals of the output terminal when the control switching device is in its non-conducting state; and the first switching device is the control switching device.  The MPPT controller of claim 49, wherein the control switching device comprises a control transistor, the control transistor including a body diode having an anode electrically connected to the first terminal of the output terminal and a cathode connected to the first terminal of the input terminal.  The MPPT controller of claim 46, wherein the control subsystem is further configured to continue operating the MPPT controller in its first mode of operation after an amount of current flowing out of the output terminal has dropped to zero.  The MPPT controller of claim 37, wherein the control subsystem is further configured to operate the MPPT controller in response to an external signal in its first mode of operation.  The MPPT controller of claim 37, wherein the control subsystem is further configured to operate the MPPT controller in its first mode of operation each time the MPPT controller powers up.  The MPPT controller of claim 37, wherein the control subsystem is further configured to cause a duty cycle of the first fixed duty cycle switching device to ramp up when the MPPT controller begins to operate in its first mode of operation.  The MPPT controller of claim 37, wherein the control subsystem is further configured to cause the MPPT controller to switch from its first mode of operation to another mode of operation after a predetermined period of time.  The MPPT controller of claim 55, wherein the other mode of operation is the second mode of operation of the MPPT controller.  The MPPT controller of claim 37, wherein the rule subsystem is further configured: comparing a first voltage signal with a threshold, the first voltage signal being a function of a voltage across the input terminal; and cause the MPPT controller to switch from its first mode of operation to another mode of operation of the MPPT controller when the first voltage signal falls below the threshold. The MPPT controller of claim 57, wherein the other mode of operation is the second mode of operation of the MPPT controller.  The MPPT controller of claim 37, wherein the control subsystem is further configured to cause the control switching device to repeatedly switch between its conducting and non-conducting states at a duty cycle in a third mode of operation of the MPPT controller that is a predetermined output current. Maintains the voltage characteristic of the MPPT controller.  The MPPT controller of claim 59, wherein the rule subsystem is further configured: compare a signal representing current flowing from the output terminal with a threshold value; and operate the MPPT controller in its third mode of operation in response to determining that the signal representing current flowing out of the output terminal is less than or equal to the threshold.  The MPPT controller of claim 60, wherein the threshold represents that current flows from the output terminal in a negative direction.  The MPPT controller of claim 59, wherein the predetermined output-current-voltage characteristic of the MPPT controller is linear such that the magnitude of the average voltage across the output terminal changes linearly with a change in the amount of average current flowing into the input terminal.  The MPPT controller of claim 59, wherein the predetermined output current-voltage characteristic of the MPPT controller is non-linear, such that the magnitude of the average voltage across the output terminal varies non-linearly with a change in the amount of average current flowing into the input terminal.

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