초록 ▼

A drive circuit for delivering high-level power to a load, and method of stopping a high power load from operating, are disclosed. The drive circuit includes a high power circuit capable of being coupled to the load and delivering the high level power thereto, and a to power circuit that controls th

A drive circuit for delivering high-level power to a load, and method of stopping a high power load from operating, are disclosed. The drive circuit includes a high power circuit capable of being coupled to the load and delivering the high level power thereto, and a to power circuit that controls the high power circuit. The low power circuit includes a first circuit portion that provides at least one control signal that is at least indirectly communicated to the high power circuit and that controls the delivering of the high level power by the high power circuit, and a second circuit portions coupled to the first circuit portion. The second circuit portion is capable of disabling the first circuit portion so that the at least one control signal avoids taking on values that would result in the high power circuit delivering the high level power to the load.

대표청구항 ▼

1. A drive circuit for delivering high-level power to an AC motor, the drive circuit comprising: a high power circuit including a set of semiconductor switching devices capable of being coupled to the motor and delivering the high level power thereto;a logic circuit generating signals to control the

1. A drive circuit for delivering high-level power to an AC motor, the drive circuit comprising: a high power circuit including a set of semiconductor switching devices capable of being coupled to the motor and delivering the high level power thereto;a logic circuit generating signals to control the semiconductor switching devices;a low power circuit to transmit the signals from the logic circuit to the high power circuit only when the low power circuit is receiving electrical power; anda safety relay having a contact connected to a power terminal of the low power circuit to control the application of power to the low power circuit, wherein the safety relay couples the power terminal of the low power circuit to ground to disable the low power circuit, and wherein the safety relay is electrically isolated from the logic circuit;wherein the safety relay is coupled to a pull-up resistor of the low power circuit, wherein the safety relay further disables the low power circuit by at least one of coupling the pull-up resistor to ground and decoupling the pull-up resistor from a power supply;wherein the safety relay is coupled to an override port of the low power circuit, and wherein the safety relay disables the power circuit by providing a first signal to the override port of the low power circuit. 2. The drive circuit of claim 1, wherein providing the first signal to the override port tri-states the output of the low power circuit. 3. The drive circuit of claim 1, wherein the safety relay includes a hardware switch that is capable of being switched between first and second states, and wherein, when the switch is switched in the first state, the safety relay provides the first signal to the override port of the low power circuit. 4. The drive circuit of claim 3, wherein the high power circuit includes at least one coil that outputs a signal indicative of a current delivered by the high power circuit to the motor, and wherein a determination is made regarding whether the signal indicative of the current is proper when the switch is switched in the first state. 5. The drive circuit of claim 1, wherein the power terminal of the low power circuit is connected to the power supply via a low-level resistor having a resistance value less than the pull-up resistor. 6. The drive circuit of claim 1, wherein the semiconductor switching devices are insulated gate bipolar transistors. 7. The drive circuit of claim 1, wherein the semiconductor switching devices deliver first, second and third phases of power. 8. The drive circuit of claim 1, wherein the semiconductor switching devices are light sensitive devices that respond to light signals. 9. A drive circuit for delivering high-level power to an AC motor, the drive circuit comprising: a high power circuit including a set of semiconductor switching devices capable of being coupled to the motor and delivering the high level power thereto;a logic circuit generating signals to control the semiconductor switching devices;a low power circuit to transmit the signals from the logic circuit to the high power circuit only when the low power circuit is receiving electrical power; andan isolation device having a terminal connected to a power terminal of the low power circuit to control the application of power to the low power circuit, wherein the isolation device couples the power terminal of the low power circuit to an externally provided signal having a first state, wherein communicating the first state is operable to disable the low power circuit, and wherein the isolation device is electrically isolated from the logic circuit;wherein the isolation device is coupled to a pull-up resistor of the low power circuit, wherein the isolation device further disables the low power circuit by coupling the pull-up resistor to the externally provided signal communicating the first state;wherein the isolation device is coupled to an override port of the low power circuit, and wherein the isolation device disables the lower power circuit by coupling the externally provided signal communication the first state to the override port of the low power circuit. 10. The drive circuit of claim 9, wherein the isolation device includes a DC-to-DC converter. 11. The drive circuit of claim 9, wherein the isolation device includes an optical isolator 12. The drive circuit of claim 9, wherein communicating the first state provides ground to the low power circuit. 13. The drive circuit of claim 9, wherein the voltage range of the externally provided signal differs from the voltage range for the application of power to the low power circuit. 14. The drive circuit of claim 13, wherein the voltage range of the externally provided signal is 0 to 12 Volts, and the voltage range for the application of power to the low power circuit is 0 to 5 Volts. 15. The drive circuit of claim 9, wherein coupling the externally provided signal communicating the first state to the override port tri-states the output of the low power circuit. 16. The drive circuit of claim 9, further comprising a hardware switch that is capable of being switched between first and second positions, and wherein, when the switch is switched in the first position, the isolation device couples the externally provided signal communicating the first state to the override port of the low power circuit. 17. The drive circuit of claim 16, wherein the high power circuit includes at least one coil that outputs a signal indicative of a current delivered by the high power circuit to the motor, and wherein a determination is made regarding whether the signal indicative of the current is proper when the switch is switched in the first state.