1. A load drive device comprising:
a load drive unit for switching onoff an output current that flows to an inductive load; and
an overcurrent protection circuit for detecting whether the output current is in an overcurrent state,
wherein the load drive unit comprises:
an output transistor connected to one end of the inductive load; and
a pre-driver for generating a control signal of the output transistor in accordance with an input signal,
wherein the pre-driver:
switches off the output transistor more slowly during overcurrent protection operation than during normal operation.
2. The load drive device of claim 1, further comprising:
a mask time generation circuit for instructing the load drive unit to carry out overcurrent protection operation when an overcurrent state of the output current has continued for a predetermined mask time.
3. The load drive device of claim 2, wherein the load drive unit has an input signal breaker for cutting off the input signal without waiting for the mask time to elapse when an overcurrent state of the output current has been detected.
4. The load drive device of claim 3, wherein the load drive device has a plurality of the inductive loads connected thereto, and has one each of the load drive unit, the overcurrent protection circuit, and the mask time generation circuit for each of a plurality of load drive lines.
5. The load drive device of claim 3, wherein the load drive device has a plurality of the inductive loads connected thereto; has one each of the load drive unit and the overcurrent protection circuit for each of a plurality of load drive lines; and has a single mask time generation circuit provided in common to the plurality of load drive lines, and a logic OR arithmetic unit for generating a logic OR signal of the overcurrent detection signals outputted from the plurality of overcurrent protection circuits and supplying the logic OR signal to the mask time generation circuit and the plurality of input signal breakers.
6. The load drive device of claim 1, wherein the load drive unit has a Schmitt buffer for transmitting the input signal to the pre-driver.
7. (canceled)
8. A load drive device comprising:
an output transistor connected to one end of an inductive load and through which output current flows to the inductive load by onoff switching;
an overcurrent protection circuit for detecting whether the output current is in an overcurrent state; and
a unit for switching off the output transistor more slowly during overcurrent protection operation than during normal operation.
9. The load drive device of claim 8, further comprising:
a mask time generation circuit for instructing the drive unit to carry out overcurrent protection operation when an overcurrent state of the output current has continued for a predetermined mask time.
10. The load drive device of claim 9, further comprising:
an input terminal to which the input signal is provided;
an input signal breaker for providing the input signal to the first drive unit during normal operation, and cutting off the input signal to the first drive unit without waiting for the mask time to elapse when an overcurrent state of the output current has been detected, the input signal breaker being connected to the input terminal.
11. The load drive device of claim 10, wherein the load drive device has a plurality of the inductive loads connected thereto, and has one each of the drive unit, the overcurrent protection circuit, and the mask time generation circuit for each of a plurality of load drive lines.
12. The load drive device of claim 10, wherein the load drive device has a plurality of the inductive loads connected thereto; has one each of the drive unit and the overcurrent protection circuit for each of a plurality of load drive lines; and has a single mask time generation circuit provided in common to the plurality of load drive lines, and a logic OR arithmetic unit for generating a logic OR signal of the overcurrent detection signals outputted from the plurality of overcurrent protection circuits and supplying the logic OR signal to the mask time generation circuit and the plurality of input signal breakers.
13. The load drive device of claim 8, further comprising a Schmitt buffer to which the input signal is provided and from which the input signal is transmitted to the first drive unit.
14. (canceled)
15. The load drive device of claim 10, further comprising a Schmitt buffer inserted between the input terminal and the input signal breaker.
16. The load drive device of claim 15, further comprising a resistor inserted between the input terminal and ground potential.
17. A load drive device comprising:
an output terminal connected to one end of an inductive load; and
an output transistor connected to the output terminal and through which output current flows to the inductive load by onoff switching;
an overcurrent protection circuit for detecting whether the output current is in an overcurrent state; and
a drive unit for switching off the output transistor more slowly during overcurrent protection operation than during normal operation.
18. The load drive device of claim 17, further comprising:
an input terminal to which the input signal is provided;
an input signal breaker for providing the input signal to the drive unit during normal operation, and cutting off the input signal to the drive unit without waiting for the mask time to elapse when an overcurrent state of the output current has been detected, the input signal breaker being connected to the input terminal.
19. The load drive device of claim 18, further comprising:
a connection detection unit to which the input signal and the voltage that appears at the output terminal are provided; and
a detection terminal for providing a signal based on output from the connection detection unit.
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. A pitch controlled wind turbine blade comprising a pressure surface side and a leeward surface side, said surfaces establishing a leading edge and a trailing edge, characterized in that said blade comprises turbulence generating means wherein said means are placed on said leeward surface side of said wind turbine blade and at the outer section of said wind turbine blade in direction of the blade tip and said turbulence generating means having a fixed shape in relation to said leeward surface side, wherein said wind turbine blade comprises at least one pitch controlling unit, and wherein the highest height of said turbulence generating means is between 0.01% and 5% of a chord length of said wind turbine blade.
2. A wind turbine blade according to claim 1, wherein said turbulence generating means are airflow noise reduction means.
3. A wind turbine blade according to claim 1, wherein said turbulence generating means are placed in an outer section ranging from 60% to 100% of the length of said blade.
4. A wind turbine blade according to claim 3, wherein said outer section is subdivided into two or more subsections, and said turbulence generating means is substantially uniform within each of said subsections.
5. A wind turbine blade according to claim 1, wherein the height of said turbulence generating means is of equal extent or is higher closest to said trailing edge of said wind turbine blade, than closest to said leading edge of said wind turbine blade.
6. A wind turbine blade according to claim 1, wherein the distance between said turbulence generating means are substantially constant.
7. A wind turbine blade according to claim 1, wherein said turbulence generating means are placed in a range between 5% and 85% from said leading edge of said wind turbine blade.
8. A wind turbine blade according to claim 7, wherein said turbulence generating means are placed in a range between 10% and 75% of the chord length, from said leading edge of said wind turbine blade.
9. A wind turbine blade according to claim 8, wherein said turbulence generating means are placed in a range between 15% and 60% of the chord length, from said leading edge of said wind turbine blade.
10. A wind turbine blade according to claim 1, wherein said turbulence generating means are attached to the wind turbine blade individually or as pairs by means of attachment means.
11. A wind turbine blade according to claim 10, wherein said attachment means is selected from a group consisting of screws, bolts, rivets, welding and adhesive.
12. A wind turbine blade according to claim 11, wherein said attachment means is an adhesive.
13. A wind turbine blade according to claim 1, wherein said turbulence generating means are attached to the wind turbine blade as part of a string of tape, a coil or a band by means of attachment means.
14. A wind turbine blade according to claim 13, wherein said attachment means is selected from the group consisting of screws, bolts, rivets, welding and adhesive.
15. A wind turbine blade according to claim 14, wherein said attachment means is an adhesive.
16. A wind turbine blade according to claim 1, wherein said turbulence generating means are plates extending in an angle between 60\xb0 and 120\xb0 from the surface of said wind turbine blades leeward surface side at said turbulence generating means.
17. A wind turbine blade according to claim 1, wherein said turbulence generating means comprises sides alternately positioned in an angle in relation to the direction of the airflow between 50\xb0 and 2\xb0 and \u221250\xb0 and \u22122\xb0.
18. A wind turbine blade according to claim 17, wherein said turbulence generating means comprises sides alternately positioned in an angle in relation to the direction of the airflow between 30\xb0 and 5\xb0 and \u221230\xb0 and \u22125\xb0.
19. A wind turbine blade according to claim 18, wherein said turbulence generating means comprises sides alternately positioned in an angle in relation to the direction of the airflow between 20\xb0 and 10\xb0 and \u221220\xb0 and \u221210\xb0.
20. A wind turbine blade according to claim 1, wherein said turbulence generating means are formed integrally with the wind turbine blade.
21. A wind turbine blade according to claim 1, wherein said turbulence generating means are vortex generators.
22. A wind turbine blade according to claim 1, wherein the highest height of said turbulence generating means is between 0.1% and 3% of the chord length of said wind turbine blade.
23. A wind turbine blade according to claim 22, wherein the highest height of said turbulence generating means is between 0.2% and 0.8% of the chord length of said wind turbine blade.
24. A wind turbine blade according to claim 1, wherein said turbulence generating means are plates extending orthogonally from the surface of said wind turbine blades leeward surface side at said turbulence generating means.
25. A wind turbine comprising at least two pitch controlled wind turbine blades and pitch controlling means for pitching said blades characterized in that said blades comprise turbulence generating means wherein said means are placed on the leeward surface sides of said wind turbine blades and at the outer section of said wind turbine blades in direction of the blade tips and said turbulence generating means having a fixed shape in relation to said leeward surface side, wherein the highest height of said turbulence generating means is between 0.01% and 5% of a chord length of said wind turbine blades.
26. A wind turbine according to claim 25, wherein said turbulence generating means are vortex generators.
27. A wind turbine according to claim 25, wherein said wind turbine is a variable speed pitch controlled wind turbine.