Electrical switch circuits are used in many applications including amplification, power, and inverter circuits. In particular, electrical switch circuits are typically used in phase switch modules. Phase switch modules are used in many applications, such as electric motor drives for industrial or automotive application to convert a direct current (hereinafter sometimes D.C.) signal to an alternating current (hereinafter sometimes A.C.) signal. Depending upon the number of electrical switch circuits in the phase switch module, a single or multiple phase switch circuit can be designed.
A typical electrical switch circuit 100 is shown schematically in FIG. 9. The switch circuit 100 includes a first and second electrical device 102, 104, respectively. In the embodiment illustrated in FIG. 9, the devices 102, 104 are transistors. In particular, the devices 102, 104 may be, for example, Metal Oxide Semiconductor Field-Effect Transistors (hereinafter sometimes MOSFET), Insulated Gate Bipolar Transistors (hereinafter sometimes IGBT) with an antiparallel diode or the like. The devices 102, 104 illustrated in FIG. 9 are configured in a half-bridge electrical configuration. A supply terminal 106 is coupled to the drain/collector (MOSFET/IGBT) of the first electrical device 102. The source/emitter of the first device 102 is coupled to the drain/collector of the second device 104. An output terminal 108 is also coupled to the source/emitter of the first device 102 and the drain/collector of the second device 104. A reference terminal 110 (e.g., ground potential) is coupled to the source/emitter of the second device 104. Switching terminals 112, 114 are separately coupled to the gates of the devices 102, 104 through gate resistors 116, 118, respectively. Additionally, diodes 120, 122 are coupled across the drain/collector and the source/emitter of the devices 102,104, respectively. In applications using MOSFET devices, the diodes 120, 122 may be either the body diode of the MOSFET or an additional diode.
A periodic full-wave, single phase A.C. drive signal is created on the output terminal 108 by switching the devices 102, 104. The devices 102, 104 are switched on by applying a trigger voltage to the terminals 112, 114, respectively. When the first device 102 is switched on, the second device 104 is switched off and the output terminal 108 is coupled to the supply terminal 106 through the first device 102. Conversely, when the second device 104 is switched on, the first device 102 is switched off and the output terminal 108 is coupled to the reference terminal 110 through the second device 104. Through the proper switching of devices 102 and 104 between the positive supply terminal 106 and the reference terminal 110, and by properly modulating each device's duty-cycle, the waveform created on the output terminal 108 is a positive full-wave, single phase drive signal.
A three phase A.C. drive signal can be created in a known manner by the cooperation of three electrical switch circuits 100A, 100B, and 100C as illustrated schematically in FIG. 10. The drains/collectors of the first transistor 102A of each circuit 100A, 100B, 100C are coupled together to a positive supply terminal 106A. Similarly, the sources/emitters of the second transistor 104A of each circuit 100A, 100B, 100C are coupled together to a reference terminal 110A. A full-wave, three phase A.C. drive signal can be created by triggering each circuit 100A, 100B, 100C at alternating times. Separate full-wave, single phase drive signals are created at each output terminal 108A, 108B, 108C. Each of the three full-wave, single phase drive signals is 120° out of phase with each other. When combined, the three full-wave, single phase A.C. drive signals create a full-wave, three phase A.C. drive signal.
A typical phase module may include one or more of the circuits illustrated in FIG. 9 and FIG. 10. In particular, some phase modules include a plurality of switch circuits 100 coupled in parallel configuration so as to increase the current capability of the phase module. The phase modules generally use a planar geometry distribution for the electrical devices of the circuits 100 in which the electrical devices are positioned on the same plane. Positioning the electrical devices on the same plane generally increases the footprint of the phase module and may require sophisticated wiring techniques such as wire bonding and laser welding. In some phase module applications, for example electric motor vehicle applications, the size and ease of manufacturability of the phase modules are important considerations.