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US 4,307,326 AGranted
Drive system for a motor
AssigneeHitachi, Ltd.
InventorsIsao Fukushima, Yoshinori Okada, Hideo Nishijima
Life of this patent
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Abstract
Disclosed is a drive system for a motor, wherein a current proportional to a change of a load of a motor is sensed by a sensing resistor. A voltage produced across the sensing resistor controls an electronic switch in a manner that the output DC voltage of a DC - DC converter is used for a motor drive power source at a normal load and yet a DC power source with a higher voltage than the output DC voltage of the DC - DC converter is used therefor at an increased load.
Claims3
A drive system for a motor comprising:
- a DC-DC converter;
- a drive circuit for driving the motor by a DC voltage outputted from said DC-DC converter;
- a sensing element for sensing a signal proportional to the current flowing through said motor;
- a DC power source with a higher voltage than the output DC voltage of said DC-DC converter;
- and
- an electronic switch which switches the power source directed to said drive circuit from said DC-DC converter to said DC power source, when a voltage appearing across said sensing element increases, including a first input terminal connected to the output of said DC-DC converter, a second input terminal connected to said DC power source, a control terminal connected to said sensing element, and an output terminal connected to said drive circuit, and which leads an output DC voltage of said DC-DC converter appearing at said first input terminal to said output terminal when a voltage appearing at said control terminal is low, and yet leads said DC power source appearing at said second input terminal to said output terminal when the voltage appearing at said control terminal increases.
3 more elements
Dependencies are inferred from the claim text.