Toko America, Inc.

Toko, Inc.

Combustion Electromagnetics Inc.

Richard Redl

Fernando Ramon Martin-Lopez

Michael A Ward

A pulse width modulated controller controls a zero-voltage switching resonant power converter or inverter. The on time of the power switch (110) of the converter or inverter is varied by an error amplifier (280) such that the output voltage of the converter or inverter maintains proportionality to a reference voltage (290). The off time is terminated by a switch-voltage detector (320) when the voltage across the power switch (110) drops below a threshold voltage (330) due to the natural resonance of the external resonating capacitor (120) and inductors (130 and 150). In the first two embodiments of the invention, a single timing capacitor (260) is employed both for determining the on time and the off time. In two other embodiments, two timing capacitors (262 and 264) are employed for separately determining the maximum allowed off time and the variable on time. A cycle-by-cycle current limit circuit comprising a current sensor (605), a comparator (610), and an R-S latch (620) may be added to the circuits representing each of the embodiments. By incorporating a soft start subcircuit (775) and an overlap detector (710, 715, 20, 725), protection against overdissipation of the power switch caused by loss of zero-voltage switching can also be implemented. The soft start subcircuit can also be triggered by a voltage detector (740, 745), which monitors the output voltage of the power converter or some other voltage within the system, such as the peak voltage across the power switch (110), to effectively implement overvoltage protection.

PWM controller for resonant converters

An error signal isolator circuit for conveying an error signal across an electrical isolation boundary such as an external pulse transformer employs a level shifting process whereby a controllable voltage is measured with respect to a reference voltage and, with any gain implemented in the process, is level shifted upward such that the higher potential is referenced to a supply voltage and the lower potential is used dynamically to control the magnitude of voltage conveyed in a pulse amplitude modulation (PAM) process. In the PAM process, an ON pulse is terminated by monitoring when a PAM current has increased to a predetermined and controllable level. An ON pulse is initiated by monitoring when the voltage across a clamp diode has decayed below its normal forward bias level, indicating a commensurate decay in PAM current, following termination of the previous ON pulse.

Error signal isolator circuit

A primary side controller for regulated power converters may be implemented as a monolithic integrated circuit in which fewer pins are required as compared to the prior art 3842 controller. The present controller includes a current limit protection function having an extended time period over which a predetermined current value is reached.

Primary side controller for regulated power converters

High efficiency, high output, compact CD ignition coil

A gate charge recovery circuit prevents generation of the voltage spike that would otherwise appear across the sense resistor that is employed to detect the current flowing through the switched terminal of a gate-driven semiconductor device when the device is turned on. The gate charge recovery circuit comprises the combination of a capacitor connected between the reference terminal of the semiconductor device and the positive terminal of a driver and a filter resistor connected between the positive terminal of the driver and the positive terminal of a voltage source.

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Onnens, Switzerland

Richard Redl