Abstract: As applications of variable frequency drives (VFD) (50) continue to grow so do challenges to provide VFD (50) systems meeting application specific requirements. For multiple reasons to include safety standards and electromagnetic interference, reduced ground leakage current is desirable. Building high output voltage VFDs (50) using transistors rated at voltages lower than the VFD output voltage is desirable for economic reasons. The apparatus and method described herein meet these challenges and others, in part by placing an electrically insulating plate (cp176) having high thermal conductivity, a low dielectric constant, and high dielectric strength between the heat sink plate of a VFD power semiconductor module and a grounded cooling plate (80 TE).

Abstract: A fault handling system for short circuit recovery in three-phase multiple-level inverter bridges, used to drive inductive loads, to assure a proper sequence for turning-off switches in the inverter bridge. Switches are selected for use in the inverter bridge so that outer switches toward the most positive and most negative bus voltage levels of the inverter bridge have lower transconductances than inner switches closest to an output phase of the inverter bridge. Additionally, driver cards driving outer switches utilize lower magnitude excitation control signals than driver cards driving inner switches. Driver cards driving outer switches, when detecting desaturation of an on-state switch, are set to automatically command the outer switch to an off-state, whereas driver cards driving inner switches wait for instructions from a controller before taking action.

Abstract: A fault handling system for short circuit recovery in three-phase multiple-level inverter bridges, used to drive inductive loads, to assure a proper sequence for turning-off switches in the inverter bridge. Switches are selected for use in the inverter bridge so that outer switches toward the most positive and most negative bus voltage levels of the inverter bridge have lower transconductances than inner switches closest to an output phase of the inverter bridge. Additionally, driver cards driving outer switches utilize lower magnitude excitation control signals than driver cards driving inner switches. Driver cards driving outer switches, when detecting desaturation of an on-state switch, are set to automatically command the outer switch to an off-state, whereas driver cards driving inner switches wait for instructions from a controller before taking action.

Abstract: A fault handling system for short circuit recovery in three-phase multiple-level inverter bridges, used to drive inductive loads, which waits for either desaturation of switches or expiration of a delay period based upon an amount of time before saturated switches are damaged before commanding off switches that are saturated, and which artificially creates a dead-short across the three-phase output to force switches conducting a fault current to desaturate. By delaying the switching-off of the inverter bridge during a fault, waiting for desaturation to occur, the statistical likelihood of switch survival is improved.

Abstract: A method and circuit enabling off-the-shelf controllers designed for use with a two-level AC drive inverter bridge (1920) to drive inverter bridges with three-or-more levels. Signals from an ordinary induction motor controller or a two-level induction motor controller (2200) are used to drive the twelve-or-more switches of a three-or-more level inverter bridge (1920), as are used in medium-and-high voltage applications. The proper sequence and timing of switching for the three-or-more-level inverter bridge is based in-part upon either the output of the six pulse-width modulators, or the output of the flux and torque control device, or the voltage control device (2210), of the two-level controller (2200).

Abstract: To protect people and equipment, three-phase AC drives need to be properly grounded, and ground faults need to be quickly detected. Conventional methods of detecting ground faults are affected by external factors that reduce their sensitivity. As an improvement on conventional methods, ground fault detection is accomplished by deriving a neutral point from the three-phase output of an AC drive, decoupling normal operating currents of the AC drive from the neutral point, resistively grounding the neutral point, and sensing when a magnitude of signals between the neutral point and ground exceed a maximum threshold level, ground faults are quickly detected. By effectively filtering normal operating currents from ground fault current, detection sensitivity is improved.

Abstract: A fault handling system for short circuit recovery in three-phase multiple-level inverter bridges, used to drive inductive loads, which waits for either desaturation of switches or expiration of a delay period based upon an amount of time before saturated switches are damaged before commanding off switches that are saturated, and which artificially creates a dead-short across the three-phase output to force switches conducting a fault current to desaturate. By delaying the switching-off of the inverter bridge during a fault, waiting for desaturation to occur, the statistical likelihood of switch survival is improved.

Abstract: An AC drive which can be applied to any power using device and in particular is a medium voltage AC drive. In a preferred embodiment, a multilevel AC drive topology is implemented, with the drive including a plurality of inverters and converter electrically coupled through electrical buses and physically coupled through their respective modular bases, and sharing a common cooling system connected to the respective heat exchangers of each component. The AC drive generally is made up of a plurality of inverter modules, which are connected to a converter module, and with each of the above components packaged in a relatively small unit having a cooling apparatus.

Abstract: An AC drive which can be applied to any power using device and in particular is a medium voltage AC drive. In a preferred embodiment, a multilevel AC drive topology is implemented, with the drive including a plurality of inverters and converter electrically coupled through electrical buses and physically coupled through their respective modular bases, and sharing a common cooling system connected to the respective heat exchangers of each component. The AC drive generally is made up of a plurality of inverter modules, which are connected to a converter module, and with each of the above components packaged in a relatively small unit having a cooling apparatus.

Abstract: To protect people and equipment, three-phase AC drives need to be properly grounded, and ground faults need to be quickly detected. Conventional methods of detecting ground faults are affected by external factors that reduce their sensitivity. As an improvement on conventional methods, ground fault detection is accomplished by deriving a neutral point from the three-phase output of an AC drive, decoupling normal operating currents of the AC drive from the neutral point, resistively grounding the neutral point, and sensing when a magnitude of signals between the neutral point and ground exceed a maximum threshold level, ground faults are quickly detected. By effectively filtering normal operating currents from ground fault current, detection sensitivity is improved.

Abstract: A ground fault relay, especially useful to detect motor leakage currents due to insulation failure. The invention operates in two (2) modes. The first mode is a “look-ahead” mode where possible motor circuit insulation failure is detected prior to the electrical motor being turned on, and the second mode is “real time” mode which detects leakage currents after the motor is turned on and during running of the motor. Processing circuitry is disclosed which enables a user to set predetermined values of leakage current to be detected and to trip the relay after comparison of the leakage current and the predetermined value, if the former is larger than the latter. This invention is able to accurately detect extremely small values of ground leakage current without experiencing nuisance tripping due to extraneous noise.

Abstract: A driver circuit is provided to control current flow through a solenoid coil of an electric liquid dispensing device including a valve element and a dispensing orifice. The driver circuit includes a bidirectional current source coupled to the solenoid coil for applying current in opposite directions through the coil. In a forward current direction, a magnetic attraction is created between the solenoid coil and the valve element to retract the valve element from the dispensing orifice. In a reverse current direction, a magnetic repulsion is created between the solenoid coil and the valving element to force the valving element toward the dispensing orifice. The magnetic flux generated in the solenoid coil by the forward current is calculated, and the reverse current is applied to substantially demagnetize the solenoid.

Abstract: An electric gun driver for controlling a solenoid within a dispenser which dispenses a liquid material, such as a heated adhesive, for application to packaging materials. The electric gun driver includes a switch mode power supply for receiving a wide range of input voltages so that the electric gun driver is adaptable to various power supply systems throughout the world. The improved electric gun driver also includes a computer for monitoring and regulating the operation of the dispenser device, a power circuit, and a hysteresis band modulator for receiving a reference current from the computer and a feedback current from an operational amplifier so as to provide a modulation signal to the power circuit. The power circuit includes two switches in the form of insulated gate bipolar transistors respectively controlled by gate driver and detector circuits so as to modulate the solenoid current for controlling and regulating the dispenser.

Abstract: A device for identifying the number of solenoids/inductive loads connected in parallel to an electric gun driver is provided. In particular, the electric gun driver, which operates a multiple number of dispensing devices with a like number of solenoids for dispensing liquid adhesive on packaging materials, determines the number of solenoids or inductive loads connected in parallel thereto for operation thereof. The device includes an input/output device, a first and a second terminal wherein any number of solenoids are connected therebetween, and a micro-controller connected to the input/output device for determining the number of solenoids connected between the first and second terminals and for supplying an operating current to control the operation of the solenoids as desired by the operator.