# US 9,437,381 B2 · Electric vehicle support equipment having a smart plug with a relay control circuit > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,437,381 B2 - Document ID: US9437381B2 - Status: Granted - Kind: B2 - Application number: 13/829,531 - Filed: 2013-03-14 - Published: 2014-09-18 - Granted: 2016-09-06 - Earliest claimed: 2013-03-14 - Assignees: Tyco Electronics Corporation - Applicants: Tyco Electronics Corporation - Inventors: Mudhafar Hassan-Ali; Jason Larson - Web page: https://patentgrep.com/patent/US9437381B2 ## CPC - B60L 3/04: Cutting off the power supply under fault conditions (protective devices and circuit arrangements in general H01H; H02H) - B60L 3/0046: {relating to electric energy storage systems, e.g. batteries or capacitors} - B60L 53/16: Connectors, e.g. plugs or sockets, specially adapted for charging electric vehicles - B60L 53/18: Cables specially adapted for charging electric vehicles - B60L 53/65: involving identification of vehicles or their battery types - H01H 47/02: for modifying the operation of the relay - H01H 47/04: for holding armature in attracted position, e.g. when initial energising circuit is interrupted; for maintaining armature in attracted position, e.g. with reduced energising current {(with switching regulator H01H47/325)} - H01H 47/10: by switching-in or -out impedance external to the relay winding - H01H 47/22: for supplying energising current for relay coil - B60L 2240/36: Temperature of vehicle components or parts - B60L 2240/527: Voltage - B60L 2240/529: Current - B60L 2270/20: Inrush current reduction, i.e. avoiding high currents when connecting the battery - H01H 9/56: for ensuring operation of the switch at a predetermined point in the AC cycle - H01H 83/20: operated by excess current as well as by some other abnormal electrical condition - Y02T 10/70: Energy storage systems for electromobility, e.g. batteries - Y02T 10/7072: Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors - Y02T 90/12: Electric charging stations - Y02T 90/14: Plug-in electric vehicles - Y02T 90/16: Information or communication technologies improving the operation of electric vehicles - Y02T 90/167: Systems integrating technologies related to power network operation and communication or information technologies for supporting the interoperability of electric or hybrid vehicles, i.e. smartgrids as interface for battery charging of electric vehicles [EV] or hybrid vehicles [HEV] - Y04S 30/14: Details associated with the interoperability, e.g. vehicle recognition, authentication, identification or billing - B60L: PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES (arrangements or mounting of electrical propulsion units or of plural diverse prime-movers for mutual or common propulsion in vehicles B60K1/00, B60K6/20; arrangements or mounting of electrical gearing in vehicles B60K17/12, B60K17/14; preventing wheel slip by reducing power in rail vehicles B61C15/08; dynamo-electric machines H02K; control or regulation of electric motors H02P); SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES (electric coupling devices combined with mechanical couplings of vehicles B60D1/64; electric heating for vehicles B60H1/00); ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL (control or regulation of electric motors H02P); MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES - H01H: ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES (contact cables H01B7/10; electrolytic self-interrupters H01G9/18; emergency protective circuit arrangements H02H; switching by electronic means without contact-making H03K17/00) - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION - Y04S: SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS ## Abstract A smart plug for coupling an electric vehicle to a power supply includes a relay including contacts, the relay configured to operate in a closed state to enable power to be supplied to the electric vehicle and an open state to prohibit power from being supplied to the electric vehicle. The smart plug also includes a microcontroller (MCU) coupled to the relay, the microcontroller outputting a control signal to operate the relay in the closed state. The smart plug further includes a zero crossing detector (ZCD) coupled to the relay, the ZCD outputting a close signal to the relay when a voltage of the power is substantially zero and outputting an open signal to the relay when a current of the power is substantially zero. ## Claims ### Claim 1 A smart plug for coupling an electric vehicle to a power supply, said smart plug comprising: a relay including contacts, the relay configured to operate in a closed state to enable power to be supplied to the electric vehicle and an open state to prohibit power from being supplied to the electric vehicle, the contacts being in a closed position when the relay is in the closed state and in an open position when the relay is in the open state, wherein the relay includes a coil that is configured to move the contacts between the closed and open positions and a current mirror having first and second paths, the first path having a first current that controls a second current of the second path, the second current flowing through the coil at a designated ratio of the first current, wherein the first path includes a first switch that controls a level of the first current through the first path and the second path includes a second switch that controls a flow of the second current through the second path; a microcontroller (MCU) coupled to the relay, the MCU outputting a relay control signal to the relay to move the contacts; and a zero crossing detector (ZCD) coupled to the relay, the ZCD outputting a close signal when a voltage of the power is substantially zero and outputting an open signal when a current of the power is substantially zero, wherein the first and second switches are configured to receive a common switch control signal that controls operation of the first and second switches, respectively, the common switch control signal being based on the relay control signal, wherein: (a) after receiving the relay control signal to move the contacts from an open position to a closed position, the relay delays activating the first and second switches to close the contacts until the voltage of the power is substantially zero based on the close signal, wherein the relay controls the first current such that the second current causes the coil to initially move the contacts to the closed positions, wherein, after the contacts are in the closed positions, the first switch is activated to decrease the first current thereby decreasing the second current through the coil to a reduced level that is sufficient to maintain the contacts in the closed position; and (b) after receiving the relay control signal to move the contacts from a closed position to an open position, the relay delays activating the second switch to open the contacts until the current of the power is substantially zero based on the open signal. ### Claim 2 (depends on 1) A smart plug in accordance with claim 1, wherein the ZCD comprises a positive voltage ZCD and a negative voltage ZCD configured to output the close signal. ### Claim 3 (depends on 1) A smart plug in accordance with claim 1, wherein the ZCD comprises a positive current ZCD and a negative current ZCD configured to output the open signal. ### Claim 4 (depends on 1) A smart plug in accordance with claim 1, wherein the ZCD comprises: a positive voltage ZCD configured to output the close signal when a voltage waveform is positive; and a negative voltage ZCD configured to output the close signal when the voltage waveform is negative. ### Claim 5 (depends on 4) A smart plug in accordance with claim 4, wherein the ZCD comprises: a positive current ZCD configured to output the open signal when a current waveform is positive; and a negative current ZCD configured to output the open signal when the current waveform is negative. ### Claim 6 (depends on 1) A smart plug in accordance with claim 1, further comprising a voltage attenuator configured to reduce an operational voltage to the ZCD. ### Claim 7 (depends on 1) A smart plug in accordance with claim 1, further comprising: an over current device (OCD), the OCD configured to detect a current overload condition and output an OCD signal that activates the second switch to move the contacts to the open positions, the second current having the reduced level when the contacts are opened. ### Claim 8 A relay control circuit for making or breaking contacts, said relay control circuit comprising: a relay configured to receive signals from a zero crossing detector (ZCD) and a microcontroller unit (MCU), the relay including: contacts configured to operate in a closed state to enable power to be supplied to an electric vehicle and an open state to prohibit power from being supplied to the electric vehicle, the contacts being in a closed position when in the closed state and in an open position when in the open state; and a coil driver coupled to the contacts, the coil driver including a coil that is configured to move the contacts between the closed and open positions and a current mirror having first and second paths, the first path having a first current that controls a second current of the second path, the second current flowing through the coil at a designated ratio of the first current, wherein the first path includes a first switch that controls a level of the first current through the first path and the second path includes a second switch that controls a flow of the second current through the second path, the ZCD outputting a close signal when a voltage of a power signal is substantially zero and outputting an open signal when a current of the power is substantially zero, and wherein the first and second switches are configured to receive a common switch control signal that controls operation of the first and second switches, respectively, the common switch control signal being based on a relay control signal from the MCU, wherein: (a) after receiving the relay control signal to move the contacts from an open position to a closed position, the relay controls the the first and second switches to close the contacts when the voltage of the power is substantially zero based on the close signal, wherein the coil driver controls the first current such that the second current causes the coil to initially move the contacts to the closed positions, wherein, after the contacts are in the closed positions, the first switch is activated to decrease the first current thereby decreasing the second current through the coil to a reduced level that is sufficient to maintain the contacts in the closed position; and (b) after receiving the relay control signal to move the contacts from a closed position to an open position, the relay controls the second switch to open the contacts when the current of the power is substantially zero based on the open signal. ### Claim 9 (depends on 8) The relay control circuit of claim 8, wherein the ZCD comprises: a positive voltage ZCD configured to output the close signal when a voltage of the power is positive; and a negative voltage ZCD configured to output the close signal when the voltage of the power is negative. ### Claim 10 (depends on 8) The relay control circuit of claim 8, wherein the ZCD comprises: a positive current ZCD configured to output the open signal when a current of the power is positive; and a negative current ZCD configured to output the open signal when the current of the power is negative. ### Claim 11 An electric vehicle support equipment (EVSE) system comprising: a nozzle configured to couple to an electric vehicle; a smart plug; and a cable coupled between the nozzle and the smart plug, the smart plug comprising: a relay including contacts, the relay configured to operate in a closed state to enable power to be supplied to the electric vehicle and an open state to prohibit power from being supplied to the electric vehicle, the contacts being in a closed position when the relay is in the closed state and in an open position when the relay is in the open state, wherein the relay includes a coil that is configured to move the contacts between the closed and open positions and a current mirror having first and second paths, the first path having a first current that controls a second current of the second path, the second current flowing through the coil at a designated ratio of the first current, wherein the first path includes a first switch that controls a level of the first current through the first path and the second path includes a second switch that controls a flow of the second current through the second path; a microcontroller (MCU) coupled to the relay, the MCU outputting a relay control signal to the relay to move the contacts; and a zero crossing detector (ZCD) coupled to the relay, the ZCD outputting a close signal when a voltage of the power is substantially zero and outputting an open signal when a current of the power is substantially zero, wherein the first and second switches are configured to receive a common switch control signal that controls operation of the first and second switches, respectively, the common switch control signal being based on the relay control signal, wherein: (a) after receiving the relay control signal to move the contacts from an open position to a closed position, the relay delays activating the first and second switches to close the contacts until the voltage of the power is substantially zero based on the close signal, wherein the relay controls the first current such that the second current causes the coil to initially move the contacts to the closed positions, wherein, after the contacts are in the closed positions, the first switch is activated to decrease the first current thereby decreasing the second current through the coil to a reduced level that is sufficient to maintain the contacts in the closed position; and (b) after receiving the relay control signal to move the contacts from a closed position to an open position, the relay delays activating the second switch to open the contacts until the current of the power is substantially zero based on the open signal. ### Claim 12 (depends on 11) The EVSE system of claim 11, wherein the smart plug further comprises a voltage attenuator configured to reduce an operational voltage to the ZCD. ### Claim 13 (depends on 1) The smart plug of claim 1, wherein the smart plug includes a plug housing that encloses the relay, the MCU, and the ZCD. ### Claim 14 (depends on 1) The smart plug of claim 1, wherein the relay control signal to move the contacts is generated in response to a proximity detector signal and a pilot signal being received at the MCU, the proximity detector signal indicating whether the electric vehicle is connected to the power supply and the pilot signal indicating whether the electric vehicle is ready for charging. ### Claim 15 (depends on 1) The smart plug of claim 1, wherein the first and second paths have a common voltage source. ### Claim 16 (depends on 1) The smart plug of claim 1, wherein the first path has a first resistance when the first switch has a first state and a second resistance when the first switch has a second state, the second resistance causing the first current to decrease. ### Claim 17 (depends on 1) The smart plug of claim 1, wherein the relay includes a resistor that is in parallel with the first switch such that the first current flows through the resistor when the first switch has a second state and the first current is short circuited around the resistor when the first switch has a first state. ### Claim 18 (depends on 1) The smart plug of claim 1, wherein the relay includes a capacitor that is coupled across the coil and is configured to control a decay of the current through the coil.