Method and circuit for clamping the recirculation current in stator windings
First Claim
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1. A circuit for clamping voltage spikes on a stator winding of a direct current motor comprising:
- a transistor having a current path connected between a voltage supply and the stator coil and having a control terminal;
a driver circuit connected to the control terminal of said transistor, anda comparator for comparing the voltage on the coil to a reference voltage and having an output connected to the control terminal of the transistor;
wherein said comparator turns on said transistor responsive to the voltage on the stator coil exceeding the voltage supply voltage.
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Abstract
A circuit for clamping the voltage spike of a stator coil winding of a brushless direct current motor is disclosed. The circuit uses a comparator to monitor the voltage on a stator winding. When a voltage spike is detected, the comparator turns on the stator winding driver transistor to clamp the voltage spike. The comparator can be designed to trigger at a desired threshold voltage so that the threshold can optimized. Additionally, the comparator can be selectively disabled to trigger when voltage spikes are anticipated.
37 Citations
20 Claims
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1. A circuit for clamping voltage spikes on a stator winding of a direct current motor comprising:
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a transistor having a current path connected between a voltage supply and the stator coil and having a control terminal; a driver circuit connected to the control terminal of said transistor, and a comparator for comparing the voltage on the coil to a reference voltage and having an output connected to the control terminal of the transistor; wherein said comparator turns on said transistor responsive to the voltage on the stator coil exceeding the voltage supply voltage. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A circuit for clamping voltage spikes on a stator coil of a direct current motor comprising:
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a high side transistor having a current path connected between a voltage supply voltage and the stator coil and having a control terminal; a high side driver circuit connected to the control terminal of said transistor, and a high side comparator for comparing the voltage on the stator coil to a reference voltage and having an output connected to the control terminal of the transistor so that the transistor turns on responsive to the voltage on the coil exceeding the voltage supply voltage; a low side transistor having a current path connected between a ground voltage and the stator coil and having a control terminal; a low side driver circuit connected to the control terminal of said low side transistor, and a low side comparator for comparing the voltage on the stator coil to a reference voltage and having an output connected to the control terminal of the low side transistor so that the transistor turns on responsive to the voltage on the coil dropping below the ground voltage. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A method for clamping voltage spikes on stator coil windings comprising the steps of:
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commutating drive current through a driver circuit to a winding through a transistor; comparing the voltage on the stator coil winding to a reference voltage for detecting a voltage spike on the coil; turning on the transistor responsive to the voltage on the coil winding exceeding voltage supply voltage. - View Dependent Claims (14, 15)
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16. A brushless, polyphase, direct-current motor having a rotor, stator coils, a commutation circuit for providing sequencing signals, and a circuit for clamping voltage spikes in the stator coils comprising:
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a transistor having a current path connected between a voltage supply and the stator coil and having a control terminal; a driver circuit connected to the control terminal of said transistor; and a comparator for comparing the voltage on the coil to a reference voltage and having an output connected to the control terminal of the transistor; wherein said comparator turns on the transistor responsive to the voltage on the stator coil exceeding the voltage supply voltage. - View Dependent Claims (17, 18, 19, 20)
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Specification