Speed control circuit for a universal motor
First Claim
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1. A circuit arrangement for the control of a universal motor (1) on an a.c. voltage supply line, havingan integrated circuit control circuit (2) having a ground connector terminal (20), a control input terminal (22), a voltage supply terminal (23) and a synchronization input terminal (24);
- at synchronization resistor (5) having one terminal connected to a phase of said a.c. voltage supply and another terminal connected to said synchronization input terminal (24);
at semiconductor switch (3), connected between first and second a.c. supply lines (14,
13) of a load current circuit, having an anode, a cathode, and a control input (ST) which is connected with an output of said control circuit (2), said control circuit (2) being adapted for phase-shift control of the universal motor (1),wherein a control signal (UST) for the control circuit (2) is applied across said control input (22) and ground terminals (25) of the control circuit (2),an RPM sensor (4) is provided for detecting (41,
42) speed of the universal motor,the control signal or said control circuit (2) is picked up by said RPM sensor directly at the motor (1) in the form of an armature voltage and furnished from a control signal output (21) of said RPM sensor to said control input (22) of said control circuit,the ground connector (20) of the control circuit (2) is connected with an internal ground point or junction (25) located in the load current circuit between the semiconductor switch (3) and an armature (M) of the universal motor (1), andthe semiconductor switch (3) is operated inversely by connecting its cathode (K) with the internal ground point or junction (25).
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Abstract
A control circuit is proposed, which can be used for the phase-shift control of an electric motor in an a.c. voltage supply line. The ground connector of the control circuit, together with the cathode of a semiconductor switch (triac), is directly connected with load current circuit. Because of this, it is possible to do without potential-separating means when it is intended to feed signals at the load current circuit directly into the control circuit. An auxiliary voltage source is connected between the synchronization input and the ground connector to maintain the function of the synchronization input.
13 Citations
10 Claims
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1. A circuit arrangement for the control of a universal motor (1) on an a.c. voltage supply line, having
an integrated circuit control circuit (2) having a ground connector terminal (20), a control input terminal (22), a voltage supply terminal (23) and a synchronization input terminal (24); -
at synchronization resistor (5) having one terminal connected to a phase of said a.c. voltage supply and another terminal connected to said synchronization input terminal (24); at semiconductor switch (3), connected between first and second a.c. supply lines (14,
13) of a load current circuit, having an anode, a cathode, and a control input (ST) which is connected with an output of said control circuit (2), said control circuit (2) being adapted for phase-shift control of the universal motor (1),wherein a control signal (UST) for the control circuit (2) is applied across said control input (22) and ground terminals (25) of the control circuit (2), an RPM sensor (4) is provided for detecting (41,
42) speed of the universal motor,the control signal or said control circuit (2) is picked up by said RPM sensor directly at the motor (1) in the form of an armature voltage and furnished from a control signal output (21) of said RPM sensor to said control input (22) of said control circuit, the ground connector (20) of the control circuit (2) is connected with an internal ground point or junction (25) located in the load current circuit between the semiconductor switch (3) and an armature (M) of the universal motor (1), and the semiconductor switch (3) is operated inversely by connecting its cathode (K) with the internal ground point or junction (25). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification
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Current AssigneeRobert Bosch GmbH
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Original AssigneeRobert Bosch GmbH
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InventorsFriedrich, Hornung, Matthias, Heisler
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Primary Examiner(s)Shoop, Jr., William M.
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Assistant Examiner(s)Sircus, Brian
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Application NumberUS08/081,385Time in Patent Office1,097 DaysField of Search318/245, 318/246, 318/248US Class Current318/245CPC Class CodesH02P 25/145 whereby the speed is regula...
