1. A filtering circuit comprising:
a clock selection unit configured to transfer a first clock or a second clock having a frequency lower than the first clock as an operating clock in response to a frequence signal; and
a filter configured to filter an input signal and generate a filtered signal in synchronization with the operating clock.
2. The filtering circuit of claim 1, wherein the filter is configured to sample the input signal in synchronization with the operating clock, and
wherein, when the second clock is transferred as the operating clock, the filter samples the input signal at a lower frequency than when the first clock is transferred as the operating clock.
3. The filtering circuit of claim 1, wherein, when the input signal of a first value is consecutively sampled at least a first critical number of times, the filter updates a logic value of the filtered signal to a first logic value corresponding to the first value, and, when the input signal of a second value is consecutively sampled at least a second critical number of times, the filter updates the logic value of the filtered signal to a second logic value corresponding to the second value.
4. The filtering circuit of claim 1, wherein, when the number of times for the input signal of a first value being sampled is greater by a first critical number of times than the number of times for the input signal of a second value being sampled, the filter updates a logic value of the filtered signal to a first logic value corresponding to the first value, and, when the number of times for the input signal of the second value being sampled is greater by a second critical number of times than the number of times for the input signal of the first value being sampled, the filter updates the logic value of the filtered signal to a second logic value corresponding to the second value.
5. The filtering circuit of claim 1, further comprising:
a clock division unit configured to divide the first clock and generate the second clock.
6. A delay locked loop comprising:
a first delay unit configured to delay an input clock and generate an output clock;
a second delay unit configured to delay the output clock and generate a feedback clock;
a phase comparison unit configured to compare a phase of the input clock to a phase of the feedback clock;
a filter unit configured to filter a comparison result of the phase comparison unit with a frequence which is determined by a lock signal and generate a filtered signal;
a lock signal generation unit configured to generate the lock signal in response to the filtered signal; and
a delay value control unit configured to control a delay value of the first delay unit in response to the filtered signal and the lock signal.
7. The delay locked loop of claim 6, wherein the filter unit is configured to filter the comparison result in synchronization with a first clock when the lock signal is deactivated and in synchronization with a second clock which has a frequency lower than the first clock when the lock signal is activated.
8. The delay locked loop of claim 6, wherein, when the lock signal is activated, the filter unit samples the comparison result of the phase comparison unit at a lower frequency than when the lock signal is deactivated.
9. The delay locked loop of claim 7, wherein the filter unit comprises:
a clock selection unit configured to transfer the first clock or the second clock as an operating clock in response to the lock signal; and
a filter configured to filter the comparison result of the phase comparison unit and generate the filtered signal in synchronization with the operating clock.
10. The delay locked loop of claim 9, wherein, when the comparison result of the phase comparison unit is consecutively sampled as a first value at least a first critical number of times, the filter updates a logic value of the filtered signal to a first logic value corresponding to the first value, and, when the comparison result of the phase comparison unit is consecutively sampled as a second value at least a second critical number of times, the filter updates the logic value of the filtered signal to a second logic value corresponding to the second value.
11. The delay locked loop of claim 9, wherein, when the number of times for the comparison result of the phase comparison unit being sampled as a first value is greater by a first critical number of times than the number of times for the comparison result being sampled as a second value, the filter updates a logic value of the filtered signal to a first logic value corresponding to the first value, and, when the number of times for the comparison result of the phase comparison unit being sampled as the second value is greater by a second critical number of times than the number of times for the input signal being sampled as the first value, the filter updates the logic value of the filtered signal to a second logic value corresponding to the second value.
12. The delay locked loop of claim 6, wherein the lock signal generation unit is configured to change a state of the lock signal when a logic value of the filtered signal transitions.
13. The delay locked loop of claim 6, wherein the delay value control unit is configured to increase or decrease the delay value of the first delay unit in response to the filtered signal and maintain the delay value of the first delay unit when the lock signal is activated.
14. A phase identity determination circuit comprising:
a phase comparison unit configured to compare a phase of a first input clock to a phase of a second input clock;
a clock selection unit configured to transfer a first clock or a second clock having a frequency lower than the first clock as an operating clock in response to a frequence signal;
a filter configured to filter a comparison result of the phase comparison unit and generate a filtered signal in synchronization with the operating clock; and
a signal generation unit configured to generate the frequence signal in response to the filtered signal.
15. The phase identity determination circuit of claim 14, wherein the filter is configured to sample the comparison result of the phase comparison unit in synchronization with the operating clock, and
wherein, when the second clock is transferred as the operating clock, the filter samples the comparison result of the phase comparison unit at a lower frequency than when the first clock is transferred as the operating clock.
16. The phase identity determination circuit of claim 14, further comprising:
a clock division unit configured to divide the first clock and generate the second clock.
17. The delay locked loop of claim 14, wherein the signal generation unit is configured to activate the frequence signal when a phase difference between the first and second input clocks is smaller than a set value.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1) An electrical powertrain for use with an engine and a traction device, comprising;
a DC motorgenerator operable to:
receive at least a portion of a first mechanical output from the engine and produce a DC power output for the traction device; and
receive DC power and produce a second mechanical output to drive the engine; and
a drivetrain operable to:
receive the DC power output from the DC motorgenerator and use the DC power output to drive the traction device; and
generate DC power directed to the DC motorgenerator to drive the engine
when the traction device is operated in a dynamic braking mode.
2) The electric powertrain of claim 1, further including a braking grid operable to dissipate as heat a portion of the DC power generated by the drivetrain.
3) The electric powertrain of claim 2, further including a chopper operable to control an amount of DC power dissipated by the braking grid.
4) The electric powertrain of claim 1, wherein the drivetrain includes at least one DC traction motor operable to act as a DC motor and a DC generator.
5) The electric powertrain of claim 1, wherein the drivetrain includes at least one AC traction motor operable to act as an AC motor and an AC generator.
6) The electric powertrain of claim 1, further including:
an AC alternator operable to receive a portion of the first mechanical output from the engine and produce an AC power output; and
a rectifier coupled with the AC alternator, the rectifier being operable to convert the AC power output to a DC power output combinable with the DC power output of the DC motorgenerator.
7) The electric powertrain of claim 6, further including a controller operable to:
set the DC motorgenerator to act as a DC motor;
set the DC motorgenerator to act as a DC generator; and
block a current from flowing from the rectifier to the AC alternator.
8) The electric powertrain of claim 6, wherein:
the engine is rated to produce a first amount of mechanical power and to receive a second amount of mechanical power, the second amount of mechanical power being less than the first amount of mechanical power;
the DC motorgenerator is sized based on the second amount of mechanical power; and
the AC alternator is sized based on a difference between the first and second amounts of mechanical power.
9) The electric powertrain of claim 8, wherein the AC alternator is further sized based on a frequency of the portion of the first mechanical output delivered to the AC alternator.
10) The electric powertrain of claim 1, wherein:
the engine is rated to produce a maximum amount of mechanical power; and
the DC motorgenerator is sized based on the maximum amount of mechanical power.
11) The electric powertrain of claim 1, wherein the drivetrain includes:
at least one AC traction motor operable to act as an AC motor and an AC generator; and
a bidirectional power converter coupled between the DC motorgenerator and the at least one AC traction motor, the bidirectional power converter being operable to act as an inverter and a rectifier to receive the DC power output from the DC motorgenerator and us the DC power output to drive the at least one AC traction motor, and to generate DC power directed to the DC motorgenerator to drive the engine when the at least one AC traction motor is operated in the dynamic mode.
12) The electric powertrain of claim 1, further including a connection to an off-board DC power source, the connection operable to receive DC power from the off-board DC power source to supplement the generated DC power.
13) The electric powertrain of claim 12, wherein the DC motorgenerator is further operable to convert at least a portion of the DC power received from the off-board DC power source to at least a portion of the second mechanical output.
14) An electric powertrain for use with an engine and a traction device, comprising:
a DC motorgenerator configured to receive at least a portion of a first mechanical output from the engine and produce a DC power output for the traction device, and to receive DC power and produce a second mechanical output to drive the engine;
at least one AC traction motor operable to act as an AC motor and an AC generator; and
a bidirectional power converter coupled between the DC motorgenerator and the at least one AC traction motor, the bidirectional power converter being operable to act as an inverter and a rectifier to receive the DC power output from the DC motorgenerator and use the DC power output to drive the at least one AC traction motor, and to generate DC power directed to the DC motorgenerator to drive the engine when the at least one AC traction motor is operated in a dynamic braking mode.
15) The electric powertrain of claim 14, further including a braking grid operable to dissipate as heat a portion of the DC power generated by the bidirectional power converter.
16) The electric powertrain of claim 15, further including a chopper operable to control an amount of DC power dissipated by the braking grid.
17) The electric powertrain of claim 14, further including:
an AC alternator operable to receive a portion of the first mechanical output from the engine and produce an AC power output; and
a rectifier coupled with the AC alternator, the rectifier being operable to convert the AC power output to a DC power output combinable with the DC power output of the DC motorgenerator.
18) The electric powertrain of claim 14, further including a connection to an off-board DC power source, the connection operable to receive DC power from the off-board DC power source to supplement the generated DC power.
19) An electric powertrain for use with an engine and a traction device, comprising:
a motorgenerator configured to:
receive at least a portion of a first mechanical output from the engine and produce a power output for the traction device; and
receive power and produce a second mechanical output to drive the engine; and
a drivetrain configured to:
receive the power output and use the power output to drive the traction device; and
generate power directed to the motorgenerator to drive the engine when the traction device is operated in a dynamic braking mode.
20) The electric powertrain of claim 19, further includes:
an alternator configured to receive a portion of the first mechanical output from the engine and produce an AC power output; and
a rectifier connected to the alternator, the rectifier being configured to convert the AC power output to a DC power output combinable with the power output of the motorgenerator, wherein:
the engine is rated to produce a first amount of mechanical power and to receive a second amount of mechanical power, the second amount of mechanical power being less than the first amount of mechanical power;
the motorgenerator has a capacity corresponding to the second amount of mechanical power; and
the alternator has a capacity corresponding to a difference between the first and second amount of mechanical power.