Active wrap around circuit for mutually couples coils
A circuit can include a voltage input and a first inductor coil of a first channel configured to interface with a second inductor coil of a second channel to induce voltage to a winding (e.g. a solenoid) via the first channel or the second channel. At least a first wraparound circuit of the first channel can be operatively connected to the first inductor coil to prevent interference from the second inductor coil from activating a wraparound circuit operatively connected to the first inductor coil.
1 . A circuit, comprising:
a voltage input;
a first inductor coil of a first channel configured to interface with a second inductor coil of a second channel to induce a voltage from the voltage input to a winding via the first channel or the second channel;
a first wraparound circuit of the first channel operatively connected to the first inductor coil, the first wraparound circuit including a first transistor operatively connected to a first rail of the first inductor coil, wherein the first transistor is configured, if a fault has occurred in either of the first channel or the second channel, to shunt short circuit current in the first inductor coil through the first wraparound circuit to a ground reference of the first wraparound circuit; and
a first switching module including a first high side switch operatively connected to a second rail of the first inductor coil and a first low side switch operatively connected to the first rail of the first inductor coil, the first switching module configured to provide excitation voltage to the first inductor coil.
2 . The circuit of claim 1 , wherein the first transistor is configured to operate in a state corresponding to a state of the first high side switch when a voltage of the first wraparound circuit exceeds a predetermined failure threshold voltage.
3 . The circuit of claim 2 , wherein the first wraparound circuit further includes a first Zener diode operatively connected between the first rail of the first inductor coil and the first transistor, the first Zener diode configured to block voltage above a predetermined threshold voltage to prevent forward bias of the first transistor induced by a counter-electromotive force of the second inductor coil.
4 . The circuit of claim 3 , wherein the predetermined threshold voltage of the first Zener diode is greater than a counter-electromotive force of the first inductor coil due to excitation of the second inductor coil.
5 . The circuit of claim 3 , wherein the first wraparound circuit further includes one or more first resistors operatively connected between the first rail of the first inductor coil and the first transistor, the one or more first resistors configured to regulate a current gain upstream of the first transistor.
6 . The circuit of claim 5 , wherein:
one of the one or more first resistors is disposed between the first Zener diode and a second transistor; and
another of the one or more first resistors is disposed between the first Zener diode and the ground reference of the first wraparound circuit.
7 . The circuit of claim 6 , wherein the one or more first resistors are configured to bias the first transistor of the first wraparound circuit.
8 . The circuit of claim 7 , further comprising:
the second inductor coil of the second channel interfaced with the first inductor coil;
a second wraparound circuit of the second channel operatively connected to the second inductor coil, wherein the second wraparound circuit includes the second transistor operatively connected to a first rail of the second inductor coil, wherein the second transistor is configured, if the fault has occurred in either of the first channel or the second channel, to shunt short circuit current in the second inductor coil through the second wraparound circuit to a ground reference of the second wraparound circuit;
a second Zener diode operatively connected between a second rail of the second inductor coil and the second transistor, the second Zener diode configured to block voltage above a predetermined threshold voltage to prevent forward bias of the second transistor induced by a counter-electromotive force of the first channel; and
second resistors operatively connected between the first rail of the second inductor coil and the second transistor, the second resistors configured to regulate a current gain upstream of the second transistor, wherein one of the second resistors is disposed between the second Zener diode and the second transistor, wherein another of the second resistors is disposed between the second Zener diode and the ground reference of the second wraparound circuit, and wherein the second resistors are configured to bias the second transistor of the second wraparound circuit.
9 . The circuit of claim 8 , further comprising:
a second switching module including a second high side switch operatively connected to the second rail of the second inductor coil and a second low side switch operatively connected to the first rail of the second inductor coil, the second switching module configured to provide excitation voltage to the second inductor coil.
10 . The circuit of claim 9 , wherein the second transistor is configured to operate in a state corresponding to a state of the second high side switch when a voltage of the second wraparound circuit exceeds a predetermined failure threshold voltage.
11 . The circuit of claim 9 , wherein the first low side switch of the first switching module and the second low side switch of the second switching module are configured for pulse width modulation control of current in the first inductor coil and the second inductor coil, respectively, when the first inductor coil and the second inductor coil are active.
12 . The circuit of claim 2 , further comprising one or more diodes operatively connected between the first switching module and the first wraparound circuit, the one or more diodes configured to control flow of current between the first switching module, the first inductor coil, and the first wraparound circuit.
13 . The circuit of claim 12 , wherein the first wraparound circuit further includes a capacitor operatively connected between the first transistor and the ground reference of the first wraparound circuit.