EP0760552A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Method and circuit for PWM mode driving a bridge and disk guide using the same
Assignee: STMicroelectronics SRL
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Filing: 1995-08-31
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Granted: —
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Expires: 2015-08-31
Abstract
Abstract The present circuit for driving by the PWM procedure a bridge circuit BR of the type having a signal input I1,I2 and a signal output O1-O2 and at least two conduction control signals C1 and C2 comprises a first virtually-square-wave generator CO1 having an output coupled to one of the two control inputs and a second virtually-square-wave generator CO2 having an output coupled to the other of the two control inputs. In this manner, the bridge being driven by two square waves, the null value of the current at the output O1-O2 no longer constitutes an intrinsic discontinuity and any value, even around zero, is controllable with relative ease.
Inventors
- 👤 Ezio Galbiati
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 07:31
CPC Classifications
H; H02; H02M; H02M7/00; H02M7/42; H02M7/44; H02M7/48; H02M7/53; H02M7/537; H02M7/5387; H02M7/53871
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
72 words
Method of driving by the Pulse Width Modulation (PWM) procedure a bridge circuit (BR) of the type having a signal input (I1,I2) and a signal output (O1,O2) and at least two control inputs (C1,C2) receiving respectively at least two conduction control signals and in which one of said signals consists of a first virtually square wave and characterized in that the other of said signals consists of a second virtually square wave.
Claim 2
Dependent Claim
18 words
Method in accordance with claim 1 in which at least one of said waves has variable duty cycle.
Claim 3
Dependent Claim
28 words
Method in accordance with claim 2 in which the duty cycle of said waves is varied in opposite direction and preferably in accordance with the same linear law.
Claim 4
Dependent Claim
31 words
Method in accordance with one of claims 2 or 3 in which the non-conduction condition of the bridge circuit corresponds to the condition in which said waves have 50% duty cycle.
Claim 5
Dependent Claim
34 words
Method in accordance with one of claims 2 to 4 in which the duty cycle is varied in relation at least to the average current supplied by the bridge (BR) to said output (O1,O2).
Claim 6
Dependent Claim
100 words
Method in accordance with claim 5 in which said conduction control signals are generated through the steps of: a) detection of the current supplied at the output (01-02), b) generation of an error signal (VE) corresponding to the average value of the difference between the detected current (VS) and a reference signal (VI) corresponding to the average current value desired at the output (01-02), and c) generation of two logical difference signals between the error signal (VE) and respectively two oscillating signals (TR1,TR2) in mutual phase opposition and in which these two difference signals correspond to said conduction control signals.
Claim 7
Dependent Claim
75 words
Circuit for driving by the PWM procedure a bridge circuit (BR) of the type having a signal input (I1,I2) and a signal output (O1,O2) and at least two conduction control inputs (C1,C2) and comprising a first virtually-square-wave generator (CO1) having its output coupled to one (C1) of said two control inputs and characterized in that it comprises a second virtually-square-wave generator (CO2) having its output coupled to the other (C2) of said two control inputs.
Claim 8
Dependent Claim
29 words
Circuit in accordance with claim 7 in which at least one of said generators (CO1,CO2) has an input (IP1,IN2) for control of the duty cycle of the generated wave.
Claim 9
Dependent Claim
56 words
Circuit in accordance with claim 8 in which the inputs (IP1,IN2) for control of the duty cycle of said generators (CO1,CO2) are coupled together and act on the respective generators (CO1,CO2) in such a manner that the duty cycle of the waves generated is varied in opposite direction and preferably in accordance with a linear law.
Claim 10
Dependent Claim
27 words
Circuit in accordance with claims 8 and 9 in which the non-conduction condition of the bridge circuit (BR) is obtained by generating waves with 50% duty cycle.
Claim 11
Dependent Claim
46 words
Circuit in accordance with claims 8 to 10 and comprising a feedback network having an input coupled to said signal output (O1,O2) to detect the average current supplied thereto and having an output coupled to the control inputs (IP1,IN2) of at least one of said generators.
Claim 12
Dependent Claim
117 words
Circuit in accordance with claim 11 and comprising: a) a detection circuit (RS) for the current supplied to said signal output (O1,O2), b) a first comparator (OA1,OA2,OA3) with a transfer function of low-pass type and having a first input coupled to the output of said detection circuit (RS) and a second input receiving a reference signal (VI) corresponding to the desired average value of the current at said signal output (O1,O2), d) a second (CO1) and a third (CO2) comparators having two inputs (IP1,IN2) of mutually different type coupled together at the output of said first comparator (OA1,OA2,OA3) and two other inputs (IN1,IP2) of mutually different type receiving respectively two oscillating signals (TR1,TR2) in mutual phase opposition.
Claim 13
Dependent Claim
31 words
Circuit in accordance with claim 12 and comprising in addition at least one generator of virtually triangular waves and having at least one output coupled to said two other inputs (IN1,IP2).
Claim 14
Dependent Claim
17 words
Circuit in accordance with one of the above claims and realized in integrated form in a chip.
Claim 15
Dependent Claim
83 words
Disk drive comprising at least a head (H), an electromagnetic actuator (VCM) for positioning of said head (H), a motor (SM) for rotation of said disk, a reading and/or writing control system (RWCS) connected to said head (H), a position control system (PCS) connected to said actuator (VCM) and a rotation control system (RCS) connected to said motor (SM) and in which said position control system (PCS) comprises a bridge circuit and a driving circuit in accordance with one of the above claims.
References Cited (Backward Citations)
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