Abstract: A method for voltage balancing series-connected power switching devices (IGBTs) each connected in parallel with a respective diverter having controllable impedance to controllably conduct current diverted from the associated power switching device, the method comprising the step of controlling each diverter to follow a series of at least two successively higher impedance states during an OFF period of the power switching devices. The series of impedance states for each diverter comprises a first impedance and then a second, higher impedance, the first impedance occurring in response to an indication of a start of the OFF period. The first impedance state preferably occurs during a tail current of the power switching device in parallel with the respective diverter and the second or later impedance state during a leakage current of that power switching device.

Abstract: A power switch driver for driving a control terminal of a power switch to drive a load, the power switch driver having a negative feedback circuit to control current delivered to the control terminal. The negative feedback circuit has a current output circuit having a current source and a current sink and serving for providing the current of the control terminal and configured to receive an output current control signal to control a magnitude of the current provided by the current output circuit, a terminal voltage input circuit for receiving a voltage from the control terminal and to output an indication of the voltage, an amplifier coupled to the terminal voltage input circuit for amplifying the terminal voltage indication to generate an amplifier output, and a reference voltage input circuit for receiving a reference voltage, having at least one resistor, and coupled to a charge supply input of the amplifier.

Abstract: A method for voltage balancing series-connected power switching devices (IGBTs) each connected in parallel with a respective diverter having controllable impedance to controllably conduct current diverted from the associated power switching device, the method comprising the step of controlling each diverter to follow a series of at least two successively higher impedance states during an OFF period of the power switching devices. The series of impedance states for each diverter comprises a first impedance and then a second, higher impedance, the first impedance occurring in response to an indication of a start of the OFF period. The first impedance state preferably occurs during a tail current of the power switching device in parallel with the respective diverter and the second or later impedance state during a leakage current of that power switching device.

Abstract: Power switch driver for driving a control terminal of a power switch to drive a load, the power switch driver having a in negative feedback circuit to control current delivered to the control terminal, the negative feedback circuit comprising:—a current output circuit comprising at least one of a current source and a current sink, the current output circuit for providing a said current of a said control terminal and configured to receive an output current control signal to control magnitude of the current provided by the current output circuit;—a terminal voltage input circuit for receiving a voltage from a said control terminal and to output an indication of said voltage;—an amplifier coupled to amplify the terminal voltage indication to generate an amplifier output; and—a reference voltage input circuit for receiving a reference voltage, comprising at least one resistor, the reference voltage input circuit coupled to a charge supply input of the amplifier, wherein—the power switch driver is configured to ge

Abstract: We describe a system for controlling very large numbers of power semiconductor switching devices (132) to switch in synchronization. The devices are high power devices, for example carrying hundreds of amps and/or voltages of the order of kilovolts. In outline the system comprises a coordinating control system (110, 120), which communicates with a plurality of switching device controllers (130) to control the devices into a plurality of states including a fully-off state, a saturated-on state, and at least one intermediate state between the fully-off and saturated-on states, synchronizing the devices in the at least one intermediate state during switching.

Abstract: The invention generally relates to methods and circuits for controlling switching of parallel coupled power semiconductor switching devices (3), for example for use in a power converter.

Abstract: Switching data is communicated in a power semiconductor switching device control system having a coordinating control system and a switching device controllers each coupled to the coordinating control system and each configured to control a respective power semiconductor switching device. Switching control data is formatted as one or more switching control data packets whose switching control data comprises data for controlling switching of the power semiconductor switching devices. The switching control data packets are sent from the coordinating control system to the switching device controllers. State data is detected, provided, and then formatted to represent states of the power semiconductor switching devices controlled in combination by the switching control data packets into acknowledgment data packets from the power semiconductor switching devices. The acknowledgment data packets are sent from the switching device controllers to the coordinating control system.

Abstract: We describe a fault-tolerant power semiconductor switching device control system (100), the control system comprising: a coordinating control system (110); and a plurality of switching device controllers (120) each coupled to said coordinating control system and each configured to control a respective power semiconductor switching device (130); wherein said coordinating control system is configured to send real time switching control data to said switching device controllers to control switching of said power semiconductor switching devices, and to receive real time acknowledgement data from said switching device controllers; wherein a said switching device controller is configured to receive said real time switching control data from said coordinating control system, to control a said power semiconductor switching device responsive to said real time switching control data, and to provide said real time acknowledgement data confirming said switching device control to said coordinating control system; and wher

Abstract: The invention generally relates to methods and circuits for controlling switching of parallel coupled power semiconductor switching devices (3), for example for use in a power converter.

Abstract: We describe a controller (130) for controlling a power semiconductor switching device (132) into a selected one of a plurality of states, the states including a fully-off state, a saturated-on state, and at least one intermediate state. The switching device controller includes a voltage sense input (142) to sense a voltage on the device; a current sense input (current feedback) to sense a current passing through the device; a negative feedback control circuit (138) coupled to the sense inputs, a control output (136) to provide to the power semiconductor switching device a drive signal with a response dependent on one or more adjustable parameters; and a circuit controller (140) to control the adjustable parameters responsive to state command data, to control the switching device into a selected state, in particular by controlling an effective resistance of the device. Preferred intermediate states include an active low current state and an active low voltage state.

Abstract: We describe techniques suitable for communicating switching data in a control system controlling, for example, kilovolts at hundreds of amps. The system comprises a central controller (110) coupled to sub-controllers (120) and thence to a plurality of switching device controllers (SDs,130), preferably in a tree-structure, each SD controlling a power semiconductor switching device such as an IGBT. The method includes formatting switching control data as one or more switching control data packets comprising data for controlling switching of a combination of the devices, sending these from the central controller to the switching device controllers, at the SDs formatting state data representing states of the switching devices controlled in combination into a plurality of acknowledgement data packets, and sending these back to the central controller. The techniques may be employed for controlling the synchronised switching of potentially, tens, hundreds or thousands of power semiconductor switching devices.

Abstract: We describe a controller (130) for controlling a power semiconductor switching device (132) into a selected one of a plurality of states, the states including a fully-off state, a saturated-on state, and at least one intermediate state. The switching device controller includes a voltage sense input (142) to sense a voltage on the device; a current sense input (current feedback) to sense a current passing through the device; a negative feedback control circuit (138) coupled to the sense inputs, a control output (136) to provide to the power semiconductor switching device a drive signal with a response dependent on one or more adjustable parameters; and a circuit controller (140) to control the adjustable parameters responsive to state command data, to control the switching device into a selected state, in particular by controlling an effective resistance of the device. Preferred intermediate states include an active low current state and an active low voltage state.

Abstract: We describe a fault-tolerant power semiconductor switching device control system (100), the control system comprising: a coordinating control system (110); and a plurality of switching device controllers (120) each coupled to said coordinating control system and each configured to control a respective power semiconductor switching device (130); wherein said coordinating control system is configured to send real time switching control data to said switching device controllers to control switching of said power semiconductor switching devices, and to receive real time acknowledgement data from said switching device controllers; wherein a said switching device controller is configured to receive said real time switching control data from said coordinating control system, to control a said power semiconductor switching device responsive to said real time switching control data, and to provide said real time acknowledgement data confirming said switching device control to said coordinating control system; and wher

Abstract: We describe a system for controlling very large numbers of power semiconductor switching devices (132) to switch in synchronisation. The devices are high power devices, for example carrying hundreds of amps and/or voltages of the order of kilovolts. In outline the system comprises a coordinating control system (110, 120), which communicates with a plurality of switching device controllers (130) to control the devices into a plurality of states including a fully-off state, a saturated-on state, and at least one intermediate state between the fully-off and saturated-on states, synchronising the devices in the at least one intermediate state during switching.

Abstract: This invention generally relates to voltage balancing among series-connected power switching devices comprising one or more insulated gate bipolar transistor (IGBT), and more particularly to a method controlling sharing of voltage among series-connected power switching devices, wherein at least one said device is an insulated gate bipolar transistor (IGBT), the method comprising: controlling the IGBT dependent on a reference signal and collector or emitter voltage of the IGBT such that during an off period of said IGBT said reference signal limits an absolute value of collector-emitter voltage of said IGBT to be within a range; and control to temporarily change during said limiting said reference signal from an initial value to a temporary clamp value to reduce said range, said change when each of said devices is in a substantially non-conducting state.