Speed detection apparatus

Claim 2

In a variable speed system for electric equipment, a speed detection apparatus for detecting speed of the electric equipment on the basis of a sampling interval so as to stably operate the control system, said speed detection apparatus comprising a pulse generator for generating signal pulses proportional to speed of the electric equipment, an electrical quantity-detecting unit for detecting an electrical quantity to be applied to the electric equipment, a sampling interval setting unit for changing a sampling interval responsive to variations in the electrical quantity, a counting unit connected to the sampling interval setting unit for counting signal pulses generated by said pulse generator in accordance with the sampling interval, and a calculating unit for determining speed of the electric equipment required for smooth operation on the basis of said counted signal pulses and said set sampling interval.

Claim 3

In a variable speed system for electric equipment, a speed detection apparatus for detecting speed of the electric equipment on the basis of a sampling interval so as to stably operate the control system, said speed detection apparatus comprising a pulse generator for generating signal pulses proportional to speed of the electric equipment, an electrical quantity-detecting unit for detecting an electrical quantity to be applied to the electric equipment, a sampling interval setting unit for changing a sampling interval responsive to variations in the electrical quantity, a counting unit connected to the sampling interval setting unit for counting signal pulses generated by said pulse generator in accordance with the sampling interval, and a calculating unit for determining speed of the electric equipment required for smooth operation on the basis of said counted signal pulses and said set sampling interval, said electric quantity-detecting unit including a current detector for detecting an input current to the electric equipment, said counting unit including a first counter for counting said signal pulses and a first register for storing therein said counted signal pulses in response to an external reset signal, said sampling interval-setting unit including a reset circuit for generating said external reset signal, a setting register for setting a set value in response to the input current detected by said current detector, a pulse oscillator for generating clock pulses at a predetermined frequency, a second counter for counting clock pulses from said pulse oscillator, a second register for storing therein said counted clock pulses in response to said external reset signal, a comparator for comparing said set value and said counted clock pulse, and said calculating unit including a CPU.

Claim 4

In a variable speed system for electric equipment, a speed detection apparatus for detecting speed of the electric equipment on the basis of a sampling interval so as to stably operate the control system, said speed detection apparatus comprising a pulse generator for generating signal pulses proportional to speed of the electric equipment, an electrical quantity-detecting unit for detecting an electrical quantity to be applied to the electric equipment, a sampling interval setting unit for changing a sampling interval responsive to variations in the electrical quantity, a counting unit connected to the sampling interval setting unit for counting signal pulses generated by said pulse generator in accordance with the sampling interval, and a calculating unit for determining speed of the electric equipment required for smooth operation on the basis of said counted signal pulses and said set sampling interval, said electric quantity-detecting unit including a current detector for detecting an input current to the electric equipment, said counting unit including a first counter for counting said signal pulses and a first register for storing therein said counted signal pulses in response to an external reset signal, said sampling interval-setting unit including a reset circuit for generating said external reset signal, a setting register for setting a set value in response to the input current detected by said current detector, a pulse oscillator for generating clock pulses at a predetermined frequency, a second counter for counting clock pulses from said pulse oscillator, a second register for storing therein said counted clock pulses in response to said external reset signal, a comparator for comparing said set value and said counted clock pulse, and said calculating unit including a CPU.