Circuit for protection from voltage spikes
A motorized system that allows for calibration by a user, and that features circuit protection and detection of motor stoppage. A motorized window-blind system is an example of such a system and is disclosed herein. In particular, a circuit is featured that comprises a TRIAC, or “triode for alternating current,” and TVS diodes, or “transient-voltage-suppression diodes,” providing voltage protection to various types of motor-related electronic components. A controller is disclosed that features measurement of voltage that is induced on a secondary winding of a motor, in order to detect certain events that occur during the operation of the motor. A calibration method is also disclosed that can account for one or both of the protection circuit and event-detecting controller. The calibration method accounts for human interaction and, in doing so, is intended toward making a calibration process of a motorized household system less prone to human error.
1. A circuit comprising:
a first triode for alternating current (TRIAC) having an MT1 terminal, an MT2 terminal, and a gate;
a first transient-voltage-suppression (TVS) diode having i) a first terminal electrically coupled to the MT2 terminal of the TRIAC and ii) a second terminal; and
a second TVS diode having i) a first terminal electrically coupled to the second terminal of the first TVS diode and ii) a second terminal electrically coupled to the MT1 terminal of the TRIAC;
wherein the first TRIAC conducts electrical current if a predetermined voltage across the second TVS diode is exceeded.
2. The circuit of claim 1 further comprising a first resistor having i) a first terminal electrically coupled to the second terminal of the first TVS diode and the first terminal of the second TVS diode and ii) a second terminal electrically coupled to the gate of the first TRIAC.
3. The circuit of claim 2 wherein the ohmic resistance of the first resistor is selected such that the first TRIAC conducts electrical current between the MT1 and MT2 terminals if the predetermined voltage across the second TVS diode is exceeded.
4. The circuit of claim 1 further comprising an opto-triac having i) a light-emitting diode (LED) and ii) a second TRIAC having a) a first terminal electrically coupled to the first terminal of the first TVS diode, b) a second terminal electrically coupled to the second terminal of the first TVS diode and the first terminal of the second TVS diode, and c) a gate configured to cause electrical current to be conducted between the first and second terminals of the second TRIAC based on light emitted by the LED.
5. The circuit of claim 4 further comprising a processor electrically coupled to the LED, wherein the processor is configured to switch the second TRIAC via the LED.
6. The circuit of claim 1 further comprising:
an AC voltage source electrically coupled to the MT1 terminal of the first TRIAC; and
a relay electrically coupled to the MT2 terminal of the first TRIAC.