Gate drive latching circuit for an auxiliary resonant commutation circuit
First Claim
1. A latching driver circuit for a relatively high power auxiliary resonant commutation pole (ARCP) circuit, the ARCP circuit including at least two electronic switching devices connected in series in opposite polarity to each other and in series with an inductor forming part of a resonant circuit, the inductor including a current sense winding for providing a signal representative of current therethrough, said latching driver circuit;
- an optical isolator for transmitting firing signals to said driver circuit for enabling gating of each of said at least two switching devices into conduction concurrently, said firing signals being relatively short in time duration compared to the desired on-time of a one of the switching devices conducting current;
first and second power stages responsive to said firing signals for generating gating signals for application to said at least two switching devices;
current sense means coupled for receiving the current representative signal and for determining therefrom the polarity of current through the inductor for identifying the one of the switching devices conducting current and generating a latch signal representative thereof; and
latch means responsive to said latch signal for latching the gating signal to the current conducting one of the switching devices into an on state for the time duration of current through the one of the switching devices.
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Accused Products
Abstract
A gate drive latching circuit for an auxiliary resonant commutation circuit for a power switching inverter includes a current monitor circuit providing a current signal to a pair of analog comparators to implement latching of one of a pair of auxiliary switching devices which are used to provide commutation current for commutating switching inverters in the circuit. Each of the pair of comparators feeds a latching circuit which responds to an active one of the comparators for latching the associated gate drive circuit for one of the pair of auxiliary commutating switches. An initial firing signal is applied to each of the commutating switches to gate each into conduction and the resulting current is monitored to determine current direction and therefore the one of the switches which is carrying current. The comparator provides a latching signal to the one of the auxiliary power switches which is actually conducting current and latches that particular power switch into an on state for the duration of current through the device. The latching circuit is so designed that the only time one of the auxiliary switching devices can be latched on is during the duration of an initial firing command signal.
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Citations
12 Claims
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1. A latching driver circuit for a relatively high power auxiliary resonant commutation pole (ARCP) circuit, the ARCP circuit including at least two electronic switching devices connected in series in opposite polarity to each other and in series with an inductor forming part of a resonant circuit, the inductor including a current sense winding for providing a signal representative of current therethrough, said latching driver circuit;
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an optical isolator for transmitting firing signals to said driver circuit for enabling gating of each of said at least two switching devices into conduction concurrently, said firing signals being relatively short in time duration compared to the desired on-time of a one of the switching devices conducting current; first and second power stages responsive to said firing signals for generating gating signals for application to said at least two switching devices; current sense means coupled for receiving the current representative signal and for determining therefrom the polarity of current through the inductor for identifying the one of the switching devices conducting current and generating a latch signal representative thereof; and latch means responsive to said latch signal for latching the gating signal to the current conducting one of the switching devices into an on state for the time duration of current through the one of the switching devices. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. In an auxiliary resonant commutated pole power converter phase leg of the type having at least two main switching devices coupled in series between relatively positive and negative dc voltage buses, each of said main switching devices having corresponding anti-parallel diodes connected thereacross, an auxiliary resonant commutated pole (ARCP) circuit comprising a pair of auxiliary switching devices connected in series in opposite polarity to one another, each of said auxiliary switching devices having corresponding anti-parallel diodes connected thereacross, and a resonant circuit coupled in series with said auxiliary switching devices, said resonant circuit including an inductor having a current sense winding embedded therein, each of the auxiliary switching devices being responsive to firing signals for establishing a resonant commutation interval for soft switching of the main switching devices, a method comprising the steps of:
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receiving a firing signal for the ARCP circuit and generating therefrom a gating signal to each of the auxiliary switching devices concurrently; detecting current in the inductor by sensing voltage on the current sense winding and determining; the polarity of the voltage so as to identify the one of the auxiliary switching devices conducting current; generating a latching signal in response to the step of detecting wherein the latching signal is associated with the current conducting one of the auxiliary switching devices;
applying the latching signal to maintain the gating signal to the current conducting one of the auxiliary switching devices so long as current continues through the inductor; andremoving the gating signal from the non-current conducting one of the auxiliary switching devices concurrently with cessation of the firing signal, wherein the firing signal is shorter in time duration than the gating signal. - View Dependent Claims (9, 10, 11, 12)
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Specification