Stepping motor drive device and method
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsHiroki Matsunaga, Shingo Fukamizu
Life of this patent
Estimating the term…
Abstract
A reference signal generation unit integrates a staircase signal, to produce reference signal VCTA whose waveform has no abrupt changes in level and which shows a current limit value. A PWM reference signal generation unit generates a PWM reference signal. A supply current measurement unit measures a supply current to a coil. A PWM control unit compares reference signal VCTA with the measurement value of the supply current measurement unit in each period of the PWM reference signal, and sets each transistor in a bridge rectification circuit in a conducting state or a nonconducting state according to the comparison result. In this way, the supply current to the coil is controlled to approach the current limit value shown by reference signal VCTA.
Claims16
A stepping motor drive device comprising:
- a supply current measurement unit operable to measure a supply current to a coil included in a stepping motor;
- a reference signal generation unit operable to generate a reference signal of a waveform which has no abrupt changes in level, the reference signal showing a target value for the supply current;
- a chopper switching circuit operable to pass the supply current to the coil in a conducting state, and stop the supply current to the coil in a nonconducting state;
- and
- a pulse width modulation control unit operable to (a) put the chopper switching circuit in the conducting state at predetermined time intervals, and (b) when in each time interval the supply current measured by the supply current measurement unit rises above the target value shown by the reference signal, put the chopper switching circuit in the nonconducting state.
A stepping motor drive method comprising:
- a supply current measurement step of measuring a supply current to a coil included in a stepping motor;
- a reference signal generation step of generating a reference signal of a waveform which has no abrupt changes in level, the reference signal showing a target value for the supply current;
- and
- a pulse width modulation control step of (a) putting a chopper switching circuit which passes the supply current to the coil in a conducting state and stops the supply current to the coil in a nonconducting state, in the conducting state at predetermined time intervals, and (b) when in each time interval the supply current measured in the supply current measurement step rises above the target value shown by the reference signal, putting the chopper switching circuit in the nonconducting state.
Dependencies are inferred from the claim text.