Marathon Electric Manufacturing Corporation

Other

Contrology Techniques Limited

Alistair A Macfarlane

Ross C McKemmie

Described are improvements in power factor control and systems embodying said improved power factor control. Improvements lie in a method of zero voltage switching in which a capacitor is placed in parallel with a switching device, and the switching device is operated responsive to a change in the polarity of the current through the capacitor. Switching therefore occurs at zero or close to zero voltage across the switching device in both on and off modes resulting in very low switching losses and electromagnetic interference. Systems employing the method include a power factor controller, LED light source, boost converter and a power source comprising one or more photovoltaic cells.

Semi resonant switching regulator, power factor control and LED lighting

An alternator regulator includes a status sensor connected to monitoring the connection of a voltage sensor to the alternator and a separate current limited monitor unit to regulate the output in accordance with the alternator current output. The sensor monitor unit includes a continuity circuit detector coupled to the voltage sensor and operable to continuously monitor the state of the connection to the alternator. A fault in the circuit connection such as a loose terminal, a broken lead or other such faults, opens the continuity circuit and generates a signal which drive the regulator off and terminates operation of the alternator, thereby protecting the alternator from possible destruction. A voltage/current mode selector receives a voltage related signal and a current related signal. A signal comparator is coupled to the voltage related signal and the sensed current related signal and generates a logic control signal applied to the selector to transmit one of the two signals. If the voltage drops, the current control is automatically triggered at a selective level to control the alternator output in accordance with the current output. The current limit control will limit the alternator output when zero voltage is occasioned by a short circuit condition. The conjoint control effected by the separate status sensing monitor positively shuts down the alternator, preventing operation of the current mode and insuring total protection of the alternator system.

Alternator regulator having output monitoring and limiting controls

A voltage regulator for a diesel engine driven alternator includes speed dip control permitting engine recovery, and a voltage signal circuit and a speed signal circuit producing a linear volts per hertz signal for controlling the RMS voltage of the alternator. A speed sensor is connected to the output of the permanent magnet generator. The signal is a filtered square wave with an accurate 50% mark-to-space ratio and converted to a pulse train coincident with the zero crossovers. A ramp circuit followed by a threshold detector and filter produces a linearly increasing voltage with decreasing speed. A level amplifier produces an output at a selected level. A rate amplifier responds to a derivative of the speed signal and clamps the level amplifier off at speed changes below a selected rate. A large and rapid speed change creates an output signal coupled to the reference side of an error amplifier to unload the alternator. The degree and rate of unloading is limited. The linear speed signal is summed with a linear RMS voltage error signal to produce a highly linear volts per hertz signal. The root mean square voltage signal is derived from the mean square of the sensed output voltage. The square root circuit is a pulse-height-width multiplier connected in a negative feedback loop to an operational amplifier to produce an implicit divider circuit. The non-inverting input is connected to the mean square signal and the amplifier forces the squared output signal equal to such mean square value, such that the output is in fact the square of the mean value.

Alternator voltage regulator with speed responsive control

A permanent magnet generator and rectifier is connected to the exciter of an alternator and a separate rectifier provides a D.C. voltage supply to a voltage regulator. A thyristor is connected in series with a second fuse across the exciter rectifier to short circuit the supply in series with a main external fuse. If the main fuse fails to open, the second fuse opens. The second fuse is potted in the regulators to prevent tampering. An overexcitation and a low voltage demand signal are sensed. The two signals are coupled to a NAND logic gate to produce an output shut-down signal. If either even is established and the first produces a signal, a shut-down signal is generated to a second comparator amplifier of latch circuit. A delay circuit connects the shut-down signal to a triggered oscillator for firing the thyristor. A voltage detector senses the rectified voltage on the thyristor and holds the oscillator off until an appropriate voltage exists to insure operation of the voltage regulator and the safety circuit. The oscillator develops a high peak, narrow current pulse for driving the thyristor fully on to trip one of the fuses.

Regulated alternator with positive fault related shut down apparatus

An automatic voltage regulator comprises means for monitoring the voltage of an alternator with a voltage crossover detector and a pulse generator so that a train of output control pulses are produced which are controlled in their mark to space ratio by the output of a circuit which senses the amplitude of the alternator output voltage.

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East Kilbride, United Kingdom

Alistair A Macfarlane