Abstract: A control apparatus for a series-connected multi-level matrix converter includes each voltage commanding device provided for each of single-phase matrix converters to generate a voltage reference to each of the single-phase matrix converters. The series-connected multi-level matrix converter includes the single-phase matrix converters. Each of the single-phase matrix converters includes a snubber circuit and a DC voltage detecting section configured to detect a DC voltage of the snubber circuit to output a DC voltage detection value. ADC over-voltage detector is configured to output a DC over-voltage signal when the DC voltage detection value exceeds a set voltage value. A voltage modifying device is, when the DC over-voltage signal is outputted, configured to decrease the voltage reference to a corresponding single-phase matrix converter among the single-phase matrix converters based on a deviation between the DC voltage detection value and the set voltage value.

Abstract: Disclosed are full-bridge power converters providing DC output power at increased conversion efficiencies, and methods of operating full-bridge power converters providing DC output power at increased conversion efficiencies. In disclosed embodiments, the switches of the full-bridge are operated to reduce conduction losses and to provide for zero-voltage switching.

Abstract: In one embodiment, a power converter system includes an input terminal for receiving a DC input voltage. The power converter system delivers AC power to a load at an output terminal. A transformer is coupled between the input terminal and the output terminal. The transformer has a first winding, a second winding, and a third winding. The output terminal is coupled to the second winding. A half-bridge circuit, coupled between the input terminal and the first winding of the transformer, includes a first switch and a second switch coupled at a common node. The first and second switches are operable to be turned on and off for causing current to flow in the transformer during operation of the power converter system. Circuitry is close coupled to the first winding of the transformer.

Abstract: A system and method for digital management and control of power conversion from battery cells. The system utilizes a power management and conversion module that uses a CPU to maintain a high power conversion efficiency over a wide range of loads and to manage charge and discharge operation of the battery cells. The power management and conversion module includes the CPU, a current sense unit, a charge/discharge unit, a DC-to-DC conversion unit, a battery protection unit, a fuel gauge and an internal DC regulation unit. Through intelligent power conversion and charge/discharge operations, a given battery type is given the ability to emulate other battery types by conversion of the output voltage of the battery and adaptation of the charging scheme to suit the battery.

Abstract: A switching power supply has an inductor that includes a coil. A chopper circuit chops the primary current drawn through the coil, for the inductor to output an induced current. A multifunction junction of the power supply has a multifunction voltage that is a function of a primary voltage that drives the coil. A first circuit suspends the chopping in response to a first sensed voltage crossing a first threshold, the first sensed voltage being a function of the multifunction voltage. A second circuit suspends the chopping in response to a second sensed voltage crossing a second threshold, the second threshold being a function of the multifunction voltage.

Abstract: A transistor is brought into conduction when, for example, a voltage between both ends of a second clamp capacitor exceeds a predetermined reference voltage. A resistance value of a discharge resistor is smaller than a value obtained by dividing the reference voltage by the maximum value of a current flowing through the discharge resistor. When the transistor is brought into conduction as a result of a voltage between both ends of the second clamp capacitor exceeding the predetermined reference voltage, a voltage applied to the discharge resistor, which results from a regenerative current, is larger one of the voltage between both ends of the second clamp capacitor and a voltage drop of the discharge resistor due to the regenerative current. The voltage drop and the voltage between both ends are smaller than a voltage between DC power supply lines, whereby it is possible to reduce an electrostatic capacitance of the discharge resistor.

Abstract: The control circuit for power supplying includes a driving module and a control module, wherein the driving module includes a first switch, a second switch, a third switch, and a fourth switch. In a first power supply mode, the first switch and the second switch are turned on, and the third switch and the fourth switch are turned off. The load current flows to the ground terminal via the first switch, the inductive load, and the second switch. When the control module sends a switching signal to the driving module, the first switch and the second switch are turned off and the third switch and the fourth switch are turned on, and the load current flows to the high potential terminal via the fourth switch, the inductive load, and the third switch due to the current inertia.

Abstract: A switching power supply circuit that obtains a predetermined DC voltage output from an input AC power supply includes a full-wave rectifier and a boost circuit connected to the rectifier. The boost circuit generates a DC output having a predetermined voltage value from the rectifier output. A power factor improving circuit controls an ON-period of an output transistor of the boost circuit, based on feedback of the DC voltage output, and a dynamic over-voltage-protection circuit controls the ON-period of the output transistor as it performs a switching operation. The switching power supply circuit facilitates an over-voltage-protection function that prevents inductor buzzing with an integrated circuit having a small number of pins.

Abstract: A battery pack includes at least one secondary battery, a fuse, and a control section. The fuse is configured to cut off charge or discharge current of the secondary battery upon detection of an abnormality of the secondary battery. The control section is configured to detect the abnormality of the secondary battery, and to perform a fusion-cutting process of fusion-cutting the fuse in accordance with the result of the detection. Upon detection of the abnormality, the control section measures a first potential being the potential of a subsequent stage of the fuse and a second potential being the potential of the secondary battery. If it is found from the result of the measurement that the first potential and the second potential are equal, the control section determines that the fuse has not been fusion-cut by the fusion-cutting process, and stops the fusion-cutting process.

Abstract: A power system is configured to provide a regulated voltage to an electrical load connected to a power source through at least one power line. The power system includes a first voltage control loop based on a remote sense signal indicative of voltage level at the load. The power system further includes a second voltage control loop based on a local sense signal indicative of a level of output voltage at the power source. The voltage level of the local sense signal is generally at a higher voltage level relative to the voltage level of the remote sense signal. Circuitry is configured to pass just the signal with the higher voltage level to ensure that the local sense control loop is a dominant control loop with respect to the remote sense control loop. This avoids effects on the power source from one or more failure modes that can occur in interconnections of the system.

Abstract: Methods and apparatus are provided for operation of a voltage source inverter. A method of operating a voltage source inverter having an output with multiple voltage phases having a DC voltage level, the method comprising sensing a low output frequency condition; determining a DC voltage offset responsive to the low output frequency condition; and applying the DC voltage offset when operating the voltage source inverter resulting in a change to the DC voltage level of the multiple voltage phases.

Abstract: Embodiments of the present technology provide short-circuit detection and protection suitable for a discharge lamp system. In several embodiments, the transformer's primary current is sensed and used to provide short-circuit protection of the secondary winding side or high voltage side.

Abstract: A control system for a power inverter is disclosed. The power inverter may be configured to supply power to a grid. The control system may include a plurality of output voltage sensors and a plurality of output current sensors configured to measure output line voltages and output line currents of the power inverter. The control system may further include a controller coupled to the power inverter. The controller may be configured to provide a control signal associated with a disturbance frequency to the power inverter. The controller may be further configured to determine an output power of the power inverter based on the output line voltages and output line currents, and determine an amplitude of oscillation in the output power caused by the disturbance frequency. The controller may also be configured to detect an islanding condition, if the amplitude of oscillation is below a threshold.

Abstract: A surge voltage target setting unit obtains a main circuit power supply voltage of a semiconductor power conversion device based on an inter-terminal voltage of a semiconductor switching element detected by a voltage detection unit, and sets a control target of a surge voltage in accordance with the obtained main circuit power supply voltage. An active gate control unit, when the semiconductor switching element is turned off, sets a quantity of voltage modification so as to modify a gate voltage in a direction raising the gate voltage, that is, in a direction lowering a turn-off speed, based on feedback of the inter-terminal voltage, when the inter-terminal voltage exceeds the control target.

Abstract: This invention relates to an ACDC converter (1) comprising a converter input (3) and a converter output (5), a pre-regulation stage (7) and a DC transformer stage (9) comprising a transformer input stage (11) and a transformer output stage (13). The transformer input stage comprises a double ended converter and there is further provided a controller (17) for providing a control signal to the double ended converter. The controller (17) operates the ACDC converter using burst mode control and by sending control signals comprising pulse sets that are designed to provide substantially zero net magnetising current in the double ended converter. The pre-regulation stage preferably comprises a buck converter which in turn also provides power factor correction to the input of the ACDC converter.

Abstract: A witching power supply unit, which suppresses switching loss in switching elements and surge voltage onto an output rectifier device and reduces the number of components, is provided. The switching power supply unit include: a switching circuit of full bridge type disposed on the input side; a rectifier circuit disposed on the output side; a transformer disposed between the switching circuit and the rectifier circuit and including a first winding on the input side, a second winding on the output side, a third winding; a surge voltage suppressing circuit connected in parallel with the switching circuit; and a driving circuit. The third winding is connected to the full bridge circuit to form a H-bridge configuration. Magnetic coupling between the first and second windings and magnetic coupling between the first and third windings are both looser than that between the second and third windings.

Abstract: A transformer 6 and a photocoupler 5 are provided to ensure insulation between a primary side circuit section 10 connected to an alternating current power supply 2, and a secondary side circuit section 20 for applying a voltage to a lamp 4. A detection circuit section 22E, provided in the secondary side circuit section 20, detects an output voltage and an output current of the lamp 4 to detect a deviation from a predetermined power. A signal corresponding to the deviation, which has been detected by the detection circuit section 22E, is transmitted to the primary side circuit section 10 via the photocoupler 5 provided between the primary side circuit section 10 and the secondary side circuit section 20. A switching control section 13, provided in the primary side circuit section 10, carries out switching control for constant power lighting based on the signal transmitted from the photocoupler 5.

Abstract: A voltage sag generator device for use in an electrical generator machine such as a wind turbine, connected to an electrical network including one to three parallel transformers connected on one side to the wind turbine via a coupling switch and circuit breakers, and earthed on the other side via circuit breakers and a control switch. The device includes mechanisms for causing short-circuits when the coupling switch and the control switch are actuated in such a way that a voltage sag having the required duration and type is generated, and mechanisms for protecting the transformers during voltage sag generation.

Abstract: The subject matter of the invention is an inverter (3), more specifically for use in a photovoltaic plant (1) with a direct voltage input (connection terminals 4; 5) for connection to a generator (2) and an alternating voltage output (connection terminals 7; 8) for feeding into an energy supply network (6) as well as with a DC-AC converter (12) with semiconductor switch elements (15) and an intermediate circuit (11), at least one short-circuit switch element (18) being connected in parallel to the generator (2), so that the voltage will not exceed a maximum voltage value neither at the connection terminals (4; 5) of the generator (2) nor between the connection terminals (9; 10) of the inverter.

Abstract: Of a pair of switching transistors connected in series between a high voltage power source and the ground, when the switching transistor on the high potential side is controlled by an RS flip-flop in response to an input signal, in order to prevent a malfunction caused by the influence of dv/dt transient phenomena of an output terminal for driving a load, a latch circuit is reset using an input signal from a low side input terminal LIN in a period during which the voltage of the output terminal for driving the load abruptly decreases.

Abstract: In one embodiment, a power converter system includes an input terminal for receiving a DC input voltage. The power converter system delivers AC power to a load at an output terminal. A transformer is coupled between the input terminal and the output terminal. The transformer has a first winding, a second winding, and a third winding. The output terminal is coupled to the second winding. A half-bridge circuit, coupled between the input terminal and the first winding of the transformer, includes a first switch and a second switch coupled at a common node. The first and second switches are operable to be turned on and off for causing current to flow in the transformer during operation of the power converter system. Circuitry is close coupled to the first winding of the transformer.

Abstract: The invention makes it possible to secure a maximum output within the capacity range of an electrical power source by preventing an output from being cut by a protective function of a converter at the time of a temporary overload. A bidirectional DC-DC converter 4 for stepping up a voltage of DC power supplied from a battery 5 is provided. A stepped-up DC power is converted to an AC power by an inverter 3-2 via a regulator 3-1 and is outputted to the load side. An input voltage V1 of the regulator 3-1 is detected by a voltage detecting portion 15 and is inputted into an output limit determining portion 16. The output limit determining portion 16 determines an output voltage value for starting to limit an inverter output according to a distance from when the input voltage V1 fell below a limit starting voltage value Vlim to a limit voltage value Va. An inverter driving portion 17 limits an output by switching FETs in the inverter 3 in accordance with this output voltage value.

Abstract: The method and circuit of the present invention provides short-circuit detection and protection in a discharge lamp system. The transformer's primary current is sensed and used to provide short-circuit protection of the secondary winding side or high voltage side. The system and method with the present invention provides short-circuit detection and protection even when the transformer's secondary winding is shorted.

Abstract: The present invention relates a system for compensating for a voltage dip and undervoltage containing a primary side and secondary side transformer, a voltage dip/swell detector, and a level detector/switch selector device, wherein the secondary side of the transformer possesses a minimally sufficient number of taps to allow the system to be modified to meet supply voltage dips. The system, in particular, allows for long term compensation of voltage dips and quick adjustment of load voltage, usually within one cycle. Methods of using the present invention are also presented.

Abstract: A method of operating a converter circuit is disclosed, wherein the converter circuit has a converter unit with a multiplicity of controllable power semiconductor switches and the converter unit is connected at the AC voltage end to an electrical AC voltage network. According to the method, the controllable power semiconductor switches are controlled by means of a control signal.

Abstract: The inverter according to the invention includes a control microcomputer including a protector circuit that stops the inverter when an anomaly is caused, a counter that counts the driving clock signals of the microcomputer from the instance at which the protector circuit starts working, and a conversion circuit that converts the clock signals counted by the counter to a numerical time expression in the time units and outputs the converted numerical time expression. The inverter according to the invention, manufacturable with low manufacturing costs and easy to operate, facilitates informing the installation manager of the period of time from the instance at which the inverter stopped due to an anomaly and such a cause, without impairing the time measurement precision.

Abstract: An exemplary embodiment includes a method for balancing thyristor bridge circuits, the method comprising, determining currents of thyristors in a first leg of thyristors of a thyristor bridge circuit, determining a first set of gate firing times for the thyristors in the first leg of thyristors responsive to determining the current of the thyristors in the first gate of thyristors, wherein the first set of gate firing times are operative to balance a current load between the thyristors in the first leg of thyristors, and gating the thyristors in the first leg of thyristors according to the first set of gate firing times.

Abstract: An MF power generator includes a DC current supply connected to an inverter. The inverter includes at least one switching element connected to a first-polarity current supply potential, and an output network. Each switching element is provided with a decoupling circuit for decoupling the switching element from a voltage of the output network. This enables the low-loss switching of the switching elements.

Abstract: A power semiconductor device M includes: first and second frames for feeding unipolar power from outside; first and second switching units which are series-connected between the first and second frames; an output frame for outputting AC power which is generated by conduction and shutoff of each switching unit to outside; a connecting wire for electrically connecting at least one pair of the first frame and the first switching unit, the first switching unit and the output frame, the output frame and the second switching unit, and the second switching unit and the second frame; a third frame which is arranged close to the output frame; and a branching wire for electrically connecting the first switching unit or the second switching unit to the third frame, whereby sufficiently suppressing surge voltage which takes place within the module even using an external snubber circuit.

Abstract: An interconnection inverter device includes a pair of capacitors connected in series to a pair of direct-current buses each connecting a direct-current power supply and the inverter; an opening/closing unit connected to either one of the pair of direct-current buses; voltage monitor units that monitor terminal voltages of the pair of capacitors respectively; and a controller that controls opening or closing of the opening/closing unit based on monitor voltages detected by the voltage monitor units.

Abstract: A DC-to-DC converter and associated methods are provided for controlling the discharge of snubber capacitances during a light/no load buck mode of operation. An operating method for a DC-to-DC converter detects conditions corresponding to a light/no load buck mode of operation, and, in response to the detection of that mode, controls the states of a first switch, a second switch, a first switched diode element, a second switched diode element, a third switched diode element, and a fourth switched diode element to facilitate discharging of a first capacitance element and a second capacitance element through a secondary winding of a transformer.

Abstract: A motor drive circuit comprises a first power line; a second power line; an H-bridge circuit that includes a first source transistor and a first sink transistor connected serially, a second source transistor and a second sink transistor connected serially, a motor coil connected at a connection point between the first source transistor and the first sink transistor, and first to fourth regenerative diodes disposed respectively on the first and second source transistors and the first and second sink transistors, the H-bridge circuit being connected between the first power line and the ground, the first source transistor and the second sink transistor being switched complementarily to the second source transistor and the first sink transistor; and a voltage constraint circuit connected between the second power line and control electrodes of the first and second source transistors, the voltage constraint circuit constraining increase in the voltage of the control electrodes of the first and second source transis

Abstract: A controller for a driving circuit of power source comprises a frequency generator, a pulse width modulator, and a driving device. The frequency generator comprises a latch circuit. The frequency generator provides a pulse signal at a first frequency after the controller is started. After the frequency generator receives an indicating signal, the frequency generator changes the frequency of pulse signal from the first frequency to a second frequency and locks the frequency of pulse signal at the second frequency. The pulse width modulator provides a PWM signal according to the pulse signal and a feedback signal which indicates a status of electric power supply of the driving circuit. The driving device controls semiconductor switches according to the PWM signal.

Abstract: In a bridge type power converter including series connectors of power semiconductor switches having first and second main terminals and a control terminal; plural steps of the series connectors connected in parallel, a gate drive circuit for limiting voltage between the first and second main terminals of the power semiconductor switch to a predetermined value only in turning off the power semiconductor switch is provided between the first main terminal and the control terminal of the power semiconductor switch.

Abstract: An inverter device includes an inverter circuit, an inverter driving unit, and a clamp diode. The inverter circuit includes an upper arm unit and a lower arm unit connected in series. The upper arm unit and the lower arm unit include switching elements that drive a load. The inverter driving unit includes a high-withstand-voltage IC that drives the switching elements of the upper arm unit and the lower arm unit. The high-withstand-voltage IC has a first terminal for supplying a reference voltage to the lower arm unit and a second terminal for supplying a high-voltage to the upper arm unit. The clamp diode clamps a potential difference between the first terminal and the second terminal.

Abstract: The present invention provides a switching power supply unit and a voltage converting method capable of suppressing a surge voltage applied to an output rectifier element more effectively. Energy in the direction of suppressing reverse voltages (surge voltages) applied to a plurality of rectifier diodes is injected into a rectifier circuit. Reverse voltages applied to the plurality of rectifier diodes are maintained to be lower than a voltage to be inherently applied for a predetermined period. Therefore, rise in the surge voltage is suppressed and rectifier elements (rectifier diodes) having low withstand voltage can be used.

Abstract: The subject matter of the invention is an inverter (3), more specifically for use in a photovoltaic plant (1) with a direct voltage input (connection terminals 4; 5) for connection to a generator (2) and an alternating voltage output (connection terminals 7; 8) for feeding into an energy supply network (6) as well as with a DC-AC converter (12) with semiconductor switch elements (15) and an intermediate circuit (11), at least one short-circuit switch element (18) being connected in parallel to the generator (2), so that the voltage will not exceed a maximum voltage value neither at the connection terminals (4; 5) of the generator (2) nor between the connection terminals (9; 10) of the inverter.

Abstract: An electronic ballast circuit for a lamp is described, wherein the ballast comprises a power factor correction circuit coupled to an inverter circuit. The inverter circuit is further coupled to a trigger circuit, which is in turn operatively connected to a hot or neutral line of a power supply by a control line. Upon closing a switch in the control line, the trigger circuit operates to place a capacitor in parallel with a base drive winding of a transistor in the inverter circuit, causing the inverter circuit to shut down. When the switch is opened, the trigger circuit shuts off and the inverter starts up and returns to an oscillating state.

Abstract: The invention relates to an energy transfer circuit. The energy transfer circuit has a first electromagnetic induction device, electrically connected to a first power supply node; a first switch circuit for connecting the first electromagnetic induction device and a second power supply node according to a first control signal; a snubber electrically connected between the first electromagnetic induction device and the second power supply node; a second electromagnetic induction device, coupled to the first electromagnetic induction device and electrically connected to the snubber and the second power supply node; and a third electromagnetic induction device coupled to the first and second electromagnetic induction devices and electrically connected to an output port of the energy transfer circuit.

Abstract: A drive transformer and associated circuitry for providing power and appropriate delays to primary switches and synchronous rectifiers in switch-mode power converters. The circuitry takes advantage of the leakage inductances of the drive transformer windings as well as the input capacitance of the primary switches (MOSFETs) to provide the necessary delays. No separate circuitry is needed to provide such delays, thereby providing reliability. Exemplary embodiments further disclose means to disable or enable the primary winding from a condition sensed on the secondary side even with a control and feedback circuit located on the secondary side.

Abstract: Feedback circuits capable of preventing output voltage overshoot in closed-loop DC regulated power supplies are presented. The circuits employ hysteresis at the input of an operational amplifier to improve the response time of the feedback circuits to a rising output voltage reaching a threshold. The feedback circuits substantially reduce, if not prevent, output voltage overshoot during start-up and hard and soft output shorts.

Abstract: A snubber circuit for use with, for example, a self-driven synchronous rectifier in a power converter is disclosed. The snubber circuit, in various embodiments, captures and recirculates energy from the leakage inductance of the converter in a substantially lossless manner. The snubber circuit comprises a capacitance for storing the energy accumulated in the leakage inductance of a transformer winding of the converter. The snubber circuit further includes a discontinuous inductor, and a switch for transferring, when on, the energy stored in the capacitance to the inductor. The energy in the inductor may then be discharged when the switch is off.

Abstract: A power converter includes a current source providing an input current, a transformer having primary and secondary windings, a switch network coupling the current source and the primary winding, and a clamping circuit coupled to the switch network. An output bus is coupled to the secondary winding and provides an output voltage. A control circuit has inputs based on the output voltage and the input current, and generates switch network control signals based on those inputs. The control circuit also generates clamping circuit control signals based on the switch network control signals. The power converter may also include a start-up control circuit configured to selectively control the switch network and the clamping circuit so as to raise the output voltage to a desired level. In some embodiments, the switch network is a full bridge, and the clamping circuit includes first and second clamping switches.

Abstract: The invention relates to a VSC-converter for converting direct voltage into auxiliary voltage and vice versa, which comprises a series connection of at least two current valves (5, 6) arranged between two poles (7, 8), a positive and a negative, of a direct voltage side of the converter, each current valve comprising several series connected circuits (12), each of which circuits comprising a semiconductor component (13) of turn-off type and a rectifying component (14) connected in anti-parallel therewith, an alternating voltage phase line (16) being connected to a midpoint (15), denominated phase output, of the series connection of current valves (5, 6) between two of said current valves while dividing the series connection into two equal parts.

Abstract: An efficient and cost effective bidirectional DC/DC converter reduces switch voltage stress via accelerated commutation allowing use of a low-cost passive clamp circuit in boost mode. The converter includes a primary circuit, transformer and secondary circuit. The primary circuit takes the form of a “full bridge converter,” a “push-pull converter,” or an “L-type converter.”. The primary circuit may include a dissipator such as a snubber circuit or small buck converter. A secondary side of the transformer is momentarily shorted by the secondary circuit by, for example, turning on at least two switches in the secondary circuit simultaneously for a minimal calibratable period when a pair of primary circuit controllers turn off to protect the primary circuit switches from voltage spikes during switching conditions.

Abstract: The Voltage Sense Method is introduced and a number of its implementations using Voltage Sense Circuit are demonstrated to solve problems associated with the start-up of parallel switching converters, each converter having output synchronous rectifiers or more general Current Bi-directional Switches: prevention of the excessive reverse current, elimination of the excess voltage stress of the input switches and elimination of the voltage overshoot in the common output voltage. The Voltage Sense circuit added to each converter generates a Simulated Output Voltage, which predicts how would the output voltage of each particular unit rise during the start-up with enabled synchronous rectifiers if that particular unit were to operate alone.

Abstract: Feedback circuits capable of preventing output voltage overshoot in closed-loop DC regulated power supplies are presented. The circuits employ hysteresis at the input of an operational amplifier to improve the response time of the feedback circuits to a rising output voltage reaching a threshold. The feedback circuits substantially reduce, if not prevent, output voltage overshoot during start-up and hard and soft output shorts.

Abstract: A protection system for an integrated circuit is disclosed. A detection system detects an overvoltage condition and provides an overvoltage condition signal to indicate a condition in which overvoltage protection may be desired. In response to the overvoltage condition signal, one or more variable resistance devices in the system, such as power devices of associated driver circuitry, are controlled to limit the voltage across such devices.

Abstract: A device which can be supplied with a given DC voltage and with a current of limited strength via a supply line. A capacitor is connected to an input of the device.

Abstract: Switching devices conjointly use snubber circuits without disposing for each switching device and is interposed between a DC neutral point N and a positive terminal plate of a DC power source. A second snubber circuit is interposed between the DC neutral point N and a negative plate terminal of a DC power source. A third snubber circuit is interposed between the DC neutral point N and an AC output terminal O. The snubber circuit suppresses the rise of the voltage when each switching device shifts from ON to OFF. The snubber circuit clamps a voltage applied to the switching device when this voltage exceeds the power source voltage during the process in which the switching device shifts from ON to OFF. The snubber circuit clamps a voltage applied to the switching device or when this voltage exceeds the power source voltage during the process.