JP2005217774A5 - - Google Patents

Claims (15)

A driving side switching means for performing switching control for intermittently supplying a path for supplying a current supplied from a power source to a load, and a circulation side switching means for performing switching control for intermittently supplying a path for supplying a circulating current from the load, A switching circuit in which a load is connected to a connection portion between the driving side switching means and the reflux side switching means,
Monitoring means for monitoring an input signal for switching control of the driving side switching means;
With reference to the time of application of an input signal for transitioning the driving side switching means monitored by the monitoring means from the ON state to the OFF state, the circulating side switching means is set to the ON state after a lapse of time including the turn-off time of the driving side switching means. And a delay means for setting a delay time for switching driving.   2. The switching circuit according to claim 1, wherein the monitoring unit monitors the input signal as an input voltage to the driving side switching unit based on a potential at a ground position of the load. An input signal for switching control of the driving side switching means is applied via an input resistor,
3. The switching circuit according to claim 1, wherein the monitoring means monitors an input signal applied via the input resistor.   4. The switching circuit according to claim 3, wherein the monitoring unit monitors the input signal as a voltage across the input resistor.   The monitoring unit includes a comparator that discriminates a voltage of the input signal and outputs a logic signal indicating whether the driving switching unit is driven in an on state or an off state. The switching circuit as described in any one of Claims 1-4. The monitoring means includes a monitoring resistor for guiding the input signal to the input terminal of the comparator,
6. The switching circuit according to claim 5, wherein the delay means is a circuit formed by the monitoring resistor and an input capacitance of an input terminal of the comparator.   Connected to the input terminal of the comparator, when the monitoring resistor is opened, the output logic signal is fixed to the side indicating that the driving side switching means is driven to the ON state. The switching circuit according to claim 6, further comprising a logic fixing resistor for applying a preset voltage.   The switching circuit according to claim 1, wherein the delay unit sets the delay time by delaying a monitoring result of the monitoring unit.   Of the switching means for driving and the switching means for circulation, the switching means on the high side of the power source is a P-channel MOS transistor, and the switching means on the low side of the power source is an N-channel MOS transistor, respectively. The switching circuit according to claim 1, wherein the switching circuit is provided.   9. The switching circuit according to claim 1, wherein each of the driving switching unit and the circulating switching unit includes an N-channel MOS transistor as a switching element. A plurality of combinations of the driving switching means and the reflux switching means are provided,
The load has the plurality of connection terminals, and each connection terminal is connected to a connection portion between the circulating switching means and the driving switching means in each combination,
11. The switching circuit according to claim 1, wherein the monitoring unit monitors an input signal for switching control of each combination of driving switching units.   12. The switching circuit according to claim 11, wherein the delay unit sets the delay time for each driving switching unit in accordance with a turn-off time of the driving switching unit of each combination.   The switching circuit according to any one of claims 1 to 12, wherein the monitoring unit monitors an input signal for switching control of the driving side switching unit with hysteresis for chattering prevention. Drive logic for generating an input signal to be applied to the drive side switching means to perform PWM control; and
In the region where the duty in the PWM control by the drive logic is close to 0 and the switching control for the circulating flow switching means is the reverse phase PWM control, The switching circuit according to claim 1, further comprising: Driving side switching means for performing switching control for interrupting a path for supplying a current supplied from a power source to a motor for generating torque for angularly displacing the steering shaft, and switching control for interrupting a path for supplying a circulating current from the motor A control device for an electric power steering system including a switching circuit in which a recirculation side switching means is connected in series to a power source, and the motor is connected to a connection portion between the drive side switching means and the recirculation side switching means Because
  The switching circuit is
    Monitoring means for monitoring an input signal for switching control to the driving side switching means;
    With reference to the time of application of an input signal for transitioning the drive-side switching means monitored by the monitoring means from an on state to an off-state, the reflux-side switching means is moved after a time period including a turn-off time of the drive-side switching means. And a delay means for setting a delay time for switching driving so as to be in an on state.