Electromagnetic flow meter
AssigneeYokogawa Electric Corporation
InventorIkuhiko Ishikawa
Life of this patent
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Abstract
An electromagnetic flow meter of a switching control system in which a DC voltage is applied to an exciting coil via switching elements, a direction of an exciting current flowing through the exciting coil is switched over at a predetermined excitation timing, and the switching elements are turned ON or OFF so as to hold the exciting current to be a predetermined value, has first and second detection resistors which are connected in series to ends of the exciting coil via the switching elements, respectively, wherein a midpoint of the first and second detection resistors is grounded to set a voltage of the midpoint as a circuit reference voltage.
Claims22
An electromagnetic flow meter of a switching control system in which a DC voltage is applied to an exciting coil via switching elements, a direction of an exciting current flowing through the exciting coil is switched over by a predetermined fundamental excitation frequency, and switching of the switching elements are controlled by an excitation switching control frequency which is higher than the fundamental excitation frequency so as to hold the exciting current constant, the electromagnetic flow meter comprises:
- first and second detection resistors which are connected in series to ends of the exciting coil via switching elements, respectively,
- wherein a midpoint of the first and second detection resistors is grounded to set a voltage of the midpoint as a circuit reference voltage.
An electromagnetic flow meter of a switching control system in which a DC voltage is applied to an exciting coil via switching elements, a direction of an exciting current flowing through the exciting coil is switched over at a predetermined excitation timing, and the switching elements are turned ON or OFF so as to hold the exciting current to be a predetermined value, the electromagnetic flow meter comprises:
- first and second detection resistors which are connected in series to ends of the exciting coil via the switching elements, respectively,
- wherein a midpoint of the first and second detection resistors is grounded to set a voltage of the midpoint as a circuit reference voltage.
An electromagnetic flow meter comprising:
- a first series circuit having a power source, a first switching element, an exciting coil, and a fourth switching element;
- a second series circuit having the power source, a second switching element, the exciting coil, and a third switching element;
- and a third series circuit having the exciting coil, the fourth switching element, and the third switching element, the electromagnetic flow meter of a switching control system in which a direction of an exciting current flowing through the exciting coil is switched over by a predetermined fundamental excitation frequency, and the first switching element and the second switching element are controlled so as to hold the exciting current to be a predetermined value, the electromagnetic flow meter comprises:
- a first detection resistor which is formed between the third switching element and a circuit reference voltage, and detects the exciting current;
- and
- a second detection resistor which is formed between the fourth switching element and the circuit reference voltage, and detects the exciting current.
An electromagnetic flow meter comprising:
- a first switching element in which a power source is connected to one end;
- a second switching element in which the power source is connected to one end;
- a third switching element in which another end of the first switching element is connected to one end, and a circuit reference voltage is connected to another end;
- a fourth switching element in which another end of the second switching element is connected to one end, and the circuit reference voltage is connected to another end;
- and an exciting coil in which a junction of the other end of the first switching element and the one end of the third switching element is connected to one end, and a junction of the other end of the second switching element and the one end of the fourth switching element is connected to another end, the electromagnetic flow meter of a switching control system in which a direction of an exciting current flowing through the exciting coil is switched over by a fundamental excitation frequency, and the first switching element and the second switching element are controlled so as to hold the exciting current constant,
- a first detection resistor which is formed between the other end of the third switching element and the circuit reference voltage, and detects the exciting current;
- and
- a second detection resistor which is formed between the other end of the fourth switching element and the circuit reference voltage, and detects the exciting current.
Dependencies are inferred from the claim text.