Microcontroller architecture for power factor correction converter
A circuit for driving a motor of a compressor includes a microcontroller that generates a reference current value for a power factor correction (PFC) converter. A programmable logic device (PLD) receives control messages from the microcontroller. The PLD sets a value in an off-time register based on a control message from the microcontroller. The PLD controls a power switch of the PFC converter to turn off in response to receiving a comparison signal indicating that a measured current in the PFC converter exceeds the reference current value. Subsequent to controlling the power switch to turn off, the PLD waits for a period of time determined by the off-time register before controlling the power switch to turn on.
1. A circuit for driving a motor of a compressor, the circuit comprising:
a microcontroller configured to generate a reference current value for a power factor correction (PFC) converter; and
a programmable logic device configured to:
receive control messages from the microcontroller;
in response to receiving a first control message from the microcontroller, set a value into an off-time register based on data in the first control message;
control a power switch of the PFC converter to turn off in response to receiving a comparison signal indicating that a measured current in the PFC converter exceeds the reference current value; and
subsequent to controlling the power switch to turn off, wait for a period of time determined by the off-time register before controlling the power switch to turn on.
2. The circuit of claim 1 wherein the programmable logic device is configured to control the power switch to turn on once both (i) the period of time has expired and (ii) the comparison signal indicates that the measured current does not exceed the reference current value.
3. The circuit of claim 1 further comprising an analog comparator configured to output the comparison signal based on a comparison between (i) an analog signal representative of the reference current value and (ii) an analog signal representative of the measured current in the PFC converter.
4. The circuit of claim 1 wherein the programmable logic device is configured to measure at least one of a turn-off delay of the power switch and a turn-on delay of the power switch.
5. The circuit of claim 4 wherein the programmable logic device is configured to selectively transmit at least one of the measured turn-off delay and the measured turn-on delay to the microcontroller.
6. The circuit of claim 4 further comprising:
a comparator configured to compare (i) a first signal indicating a voltage across the power switch and (ii) a first threshold,
wherein the programmable logic device is configured to measure the turn-on delay of the power switch as a delay between (i) controlling the power switch to turn on and (ii) the comparator indicating that the first signal exceeds the first threshold.
7. The circuit of claim 1 wherein the programmable logic device is configured to:
receive a second message of the control messages, wherein the second message includes a plurality of bits; and
drive values of the plurality of bits respectively onto a plurality of pins that corresponds one-to-one to the plurality of bits.
8. The circuit of claim 1 wherein:
the microcontroller is configured to program the programmable logic device using a programming file encoded in a compressed file format; and
the compressed file format includes serialized instructions for execution by the microcontroller without performing a decompression operation to recover the programming file.
9. The circuit of claim 1 wherein:
the microcontroller includes an operational amplifier, a comparator, and a dedicated pin;
the operational amplifier is configured to sample the measured current;
the comparator is configured to compare the measured current from the operational amplifier to the reference current value and assert the comparison signal in response to the measured current exceeding the reference current value; and
the comparison signal is output from the microcontroller on the dedicated pin.
10. The circuit of claim 1 wherein:
the microcontroller includes a first serial interface;
the programmable logic device includes:
a second serial interface in communication with the first serial interface, and
a dedicated pin;
the programmable logic device is configured to receive the control messages from the microcontroller via the second serial interface; and
the programmable logic device is configured to receive the comparison signal on the dedicated pin.
11. A control method for a programmable logic device, the method comprising:
in response to the programmable logic device receiving a first control message from a microcontroller, setting a value based on data in the first control message into an off-time register of the programmable logic device;
in response to the programmable logic device receiving a comparison signal indicating that a measured current in a power factor correction (PFC) converter exceeds a reference current value, (i) controlling, using the programmable logic device, a power switch of the PFC converter to turn off and (ii) starting a timer; and
controlling, using the programmable logic device, the power switch to turn on in response to a value of the timer reaching the value in the off-time register.
12. The method of claim 11 further comprising controlling the power switch to turn on once both (i) the value of the timer reaches the value in the off-time register and (ii) the comparison signal indicates that the measured current does not exceed the reference current value.
13. The method of claim 11 further comprising generating the comparison signal based on a comparison between (i) an analog signal representative of the reference current value and (ii) an analog signal representative of the measured current in the PFC converter.
14. The method of claim 11 further comprising measuring, using the programmable logic device, at least one of a turn-off delay of the power switch and a turn-on delay of the power switch.
15. The method of claim 14 further comprising selectively transmitting at least one of the measured turn-off delay and the measured turn-on delay from the programmable logic device to the microcontroller.
16. The method of claim 14 wherein:
the method further comprises comparing (i) a first signal indicating a voltage across the power switch and (ii) a first threshold; and
the turn-on delay of the power switch is measured as a delay between (i) controlling the power switch to turn on and (ii) the first signal exceeding the first threshold.
17. The method of claim 11 further comprising:
receiving, using the programmable logic device, a second control message including a plurality of bits; and
driving, using the programmable logic device, values of the plurality of bits respectively onto a plurality of pins that corresponds one-to-one to the plurality of bits.
18. The method of claim 11 further comprising programming, using the microcontroller, the programmable logic device using a programming file encoded in a compressed file format, wherein the compressed file format includes serialized instructions that are executable by the microcontroller without performing a decompression operation to recover the programming file.
19. The method of claim 11 further comprising:
sampling the measured current measuring using an operational amplifier;
comparing, using a comparator of the microcontroller, the measured current to the reference current value;
asserting the comparison signal in response to the measured current exceeding the reference current value; and
outputting, on a first dedicated pin of the microcontroller, the comparison signal.
20. The method of claim 11 further comprising:
receiving, on a dedicated pin of the programmable logic device, the comparison signal; and
receiving, via a first serial interface of the programmable logic device, control messages from a second serial interface of the microcontroller, wherein the first serial interface is physically distinct from the dedicated pin.