Pulse train timing
How long is each pulse, how long the gap, how many pulses fit in one gate, and what fraction of the time is the drive on?
- n
- Pulses per gate
- p
- Pulse period, µs
- t
- Pulse on-time, µs
- e
- Effective duty, %
- f
- Pulse frequency, kHz
- D
- Pulse duty, %
- g
- Gate frequency, Hz
- G
- Gate duty, %
LaTeX
p = \frac{1}{f} \qquad t = p \cdot \frac{D}{100} \qquad n = \left\lfloor \frac{G}{100} \cdot \frac{f}{g} \right\rfloor \qquad e = \frac{D \cdot G}{100}
Method
- The pulse period is one over the pulse frequency. Kilohertz in, so the period comes out in fractions of a millisecond; it is reported in microseconds.
- The on-time is the period times the pulse duty; the off-time is what is left of the period.
- The gate is open for its own period times its duty. Divide that open window by the pulse period and round down: only whole pulses count, and a pulse the gate cuts in half is not a pulse the cell sees.
- The effective duty is the two duties multiplied — the fraction of all time, gate and pulses together, that the drive is actually delivering. Average power is peak power times this.
Assumptions
- Both waveforms are ideal rectangles with instant edges and no jitter. A real gate has a rise time, and the first pulse after it opens is shorter than the rest.
- The pulse train and the gate are not synchronised. If they were locked — one gate edge on every Nth pulse edge — the count would be exact rather than rounded down. Meyer's circuits derived both from one clock, so on his bench it was exact.
- Nothing here is physics; it is bookkeeping for the calculations that follow. The interesting question — what the cell does with n pulses — is the step charging calculation's.