Apparatus and method for forced sharing of parallel MOSFET switching losses
AssigneeKollmorgen Corporation
InventorScott B. Donaldson
Life of this patent
Estimating the term…
Abstract
A system for sharing of switching losses of parallel transistors is disclosed. The system includes a plurality of switching transistors connected in parallel for providing a current to a load. A pulse generator provides pulse width modulated pulse cycles in response to the load current each pulse cycle having a pulse signal. An alternate selector is responsive to said pulse cycles, and provides the pulse cycles to the transistors, such that for each pulse cycle a predetermined transistor turns ON substantially prior to the other transistors, dissipating substantially all the turn ON losses, and a predetermined transistor turns OFF substantially later than other transistors, dissipating substantially all the turn OFF losses.
Claims20
A system for sharing of switching losses of parallel transistors comprising:
- a plurality of switching transistors connected in parallel for providing a current to a load;
- a pulse generator providing pulse width modulated pulse cycles in response to said current each pulse cycle having a pulse signal;
- an alternate selector responsive to said pulse cycles, said alternate selector providing said pulse cycles to said transistors, such that for each pulse cycle a predetermined transistor turns ON substantially prior to the other transistors, dissipating substantially all the turn ON losses, and a predetermined transistor turns OFF substantially later than other transistors, dissipating substantially all the turn OFF losses.
In a system for sharing of switching losses of MOSFET transistors connected in parallel, said MOSFET transistors being turned ON and OFF in response to a cyclic pulse train, each cycle beginning at a start of a pulse, an alternate selector comprising:
- a time delay circuit providing a delayed version of said pulse;
- a multiplex controller responsive to said pulse;
- and
- a plurality of multiplexers responsive to said multiplex controller, such that for each cycle a different multiplexer is selected, said selected multiplexer coupling said pulse to a selected transistor to turn ON substantially prior to the other transistors thereby dissipating substantially all the turn ON losses, said selected multiplexer coupling said delayed version of said pulse to said selected transistor to turn OFF substantially later than the other transistors thereby dissipating substantially all the turn OFF losses.
In a system for sharing of switching losses of MOSFET transistors connected in parallel, said MOSFET transistors being turned ON and OFF in response to a cyclic input pulse train, each cycle beginning at a start of an input pulse, an alternate selector comprising:
- a logic circuit providing for each said cycle a switching loss pulse having no turn ON delay and having a turn OFF delay, said switching loss pulse driving a selected MOSFET transistor, said logic circuit further providing a plurality of remaining switching pulses having turn ON delay and having no turn OFF delay, said plurality of remaining switching pulses driving remaining MOSFET transistors.
A method for sharing of switching losses of parallel switching transistors comprising the steps of:
- providing a current to a load via said plurality of switching transistors connected in parallel;
- providing pulse cycles each having a pulse in response to said current to turn ON and OFF said transistors;
- substantially turning ON a predetermined transistor among said plurality of transistors prior to other transistors in each pulse cycle thereby dissipating substantially all the turn ON losses in said pulse cycle;
- and
- substantially turning OFF a predetermined transistor among said plurality of transistors later than other transistors in each pulse cycle, thereby dissipating all the turn OFF losses in said pulse cycle.
Dependencies are inferred from the claim text.