Non-feedback type load current controller

• US 20070030068A1
• Filed: 02/16/2006
• Published: 02/08/2007
• Est. Priority Date: 08/08/2005
• Status: Active Grant

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Nishizawa, Osamu, Motonobu, Masao, Matsumoto, Shuuiti, Watanabe, Tetsushi
• Granted Patent: US 7,609,496 B2
• Time in Patent Office: Days
• US Class Current: 330/257
• CPC Class Codes: F16H 2061/1208 with diagnostic check cycles; Monitoring of failures
• CPC Class Codes: F16H 2061/1268 Electric parts of the controller, e.g. a defect solenoid, wiring or microprocessor
• CPC Class Codes: F16H 2061/1292 the failing part is the power supply, e.g. the electric power supply
• CPC Class Codes: F16H 61/12 Detecting malfunction or potential malfunction, e.g. fail safe in control of hydrostatic gearing F16H61/4192; Circumventing or fixing failures

Abstract

An electrical load is supplied with power from a driving power source, and a microprocessor (CPU) controls the opening/closing current supply rate (duty factor) of an opening/closing element in accordance with target current and driving power source voltage so that open loop control is carried out to achieve predetermined target current. The voltage between both the ends of a current detecting resistor connected to the ground side of the opening/closing element is input as a monitoring voltage from a current detecting amplifying circuit portion through a multichannel AD converter to CPU. When the error between the comparison target voltage corresponding to the target current and the monitoring voltage is above a first permissible error, CPU judges that there is an abnormality sign, and if the error is above a larger second permissible error, CPU judges that there is appearing abnormality. Accordingly, an abnormality sign of a semi-wire-breaking/semi-short-circuit state of the electrical load can be sensed, and abnormality notification can be carried out.

Claims

1. A non-feedback type load current device comprising:

a power supply driving circuit portion constructed by an in-series circuit comprising a driving power source, an inductive electrical load and an opening/closing element; and

a power supply control circuit portion for controlling a current supply rate corresponding to the rate between a current supply term and a current supply period of the opening/closing element in response to the values of a supply target current and a driving power source voltage to be applied to the electrical load, wherein the power supply driving circuit portion comprises a current detecting resistor connected between the opening/closing element and a ground circuit of the driving power source, a current detecting amplifying circuit portion provided with an operational amplifier for amplifying the voltage between both the terminals of the current detecting resistor and a smoothening capacitor that is provided to at least one of an input circuit and an output circuit of the operational amplifier and achieves a measurement voltage substantially proportional to the average value of the voltage between both the terminals of the current detector resistor, and a commutating circuit that is connected to the electrical load in parallel and subjects the load current supplied when the opening/closing element is under the close circuit condition to flow-back and attenuation when the opening/closing element is opened, and the power supply control circuit portion is equipped with a microprocessor supplied with power from a control power source unit that is supplied with power from the driving power source and generates a stabilized control power source voltage lower than the driving power source voltage, a multi-channel AD converter to which plural analog signals are input, and a non-volatile program memory that stores a load current control program in cooperation with the microprocessor and contains a program as an abnormality sign detecting unit, and wherein the output of the operational amplifier is input to the microprocessor through the multi-channel AD converter as a monitor voltage which is limited to a value not more than the control power source voltage, the abnormality sign detecting unit generates an abnormality notification instructing output when the relative error between the comparison target voltage corresponding to the supply target current and the monitor voltage is out of a first permissible error width in which the relative error is slightly deviated from a normal value range, and the measurement voltage when the abnormality sign detecting unit carries out abnormality detection is set to a value less than the control power source voltage.

2. The non-feedback type load current controller according to claim 1, wherein the non-volatile program memory further contains a program serving as an appearing abnormality detecting unit and a driving stop unit, and the appearing abnormality detecting unit generates an abnormality notification instructing output under an excessively large current state or excessively small current state where the relative error between a comparison target voltage corresponding to the supply target current and the monitoring voltage is out of a second permissible error larger than the first permissible error width, and the driving stop unit acts to set an opening/closing instructing output to the opening/closing element to a full-open instruction when the appearing abnormality detecting unit detects at least the excessively large current state.

3. The non-feedback type load current controller according to claim 1, wherein the non-volatile program memory further contains a program serving as a non-operation low current setting unit, and the non-operation low current setting unit temporarily supplies as the supply target current non-operation low current having a level at which the electrical load does not effectively operate, for a predetermined short term in a non-operating time zone of the electrical load.

4. The non-feedback type load current controller according to claim 1, wherein the operational amplifier of the current detecting amplifying circuit portion operates under application of the driving power source voltage of the electrical load as a power source voltage, the measurement voltage corresponding to the output of the operational amplifier is applied to an input terminal of the multichannel AD converter as a monitoring voltage through a current limiting resistor, a voltage limiting diode for limiting the monitoring voltage to a control power source voltage level is connected to an input terminal of the multichannel AD converter, the power supply driving circuit portion is further equipped with an over-current abnormality detecting circuit, and the over-current abnormality detecting circuit stops a current supply instruction to the opening/closing element when the monitoring voltage further increases and exceeds a predetermined limiting threshold value after the monitoring voltage is limited to the control voltage level by the voltage limiting diode.

5. The non-feedback type load current controller according to claim 1, wherein the power supply driving circuit portion is further equipped with a wire breaking abnormality detecting circuit and the non-volatile program memory further contains a program serving as a wire breaking abnormality detecting unit, and wherein the wire breaking abnormality detecting circuit comprises a leakage resistor supplied with minute current through the electrical load under an open circuit state of the opening/closing element, and a level converting circuit for digitalizing the applied voltage level of the leakage level and inputting a judging logic signal to the microprocessor, and the wire breaking abnormality detecting unit carries out a wire breaking abnormality judgment and generates an abnormality notification instructing output when no applied voltage to the leakage resistor occurs under an open instruction state of the opening/closing element.

6. The non-feedback type load current controller according to claim 1, wherein the non-volatile program memory further contains a program serving as a proper current supply rate calculating unit in response to the detection output of a temperature sensor for detecting the environmental temperature of the electrical load, and the proper current rate calculating unit calculates a current supply rate that is proportional to target current for the electrical load, inversely proportional to the driving power source voltage and proportional to the load resistance of the electrical load estimated from the environmental temperature detected by the temperature sensor, and determines the ratio between a current supply instruction term and a current supply period of the opening/closing instruction output to the opening/closing element.

7. The non-feedback type load current controller according to claim 6, wherein the non-volatile program memory further contains a program serving as a load temperature increase estimating unit and an abnormality judging and correcting unit, and wherein the load temperature increase estimating unit estimates a present temperature increase value of the electrical load in association with a current supply past record to the electrical load and the thermal time constant of the electrical load, and adds the temperature increase value thus estimated with the environmental temperature detected by the temperature sensor, the abnormality judging and correcting unit reduces, in response to the temperature increase value of the electrical load estimated by the load temperature increase estimating unit, the value of the comparison target voltage for which a band comparison judgment is carried out by the abnormality sign detecting unit or the appearing abnormality detecting unit, or increased the value of the monitoring voltage, and the proper current supply rate calculating unit determines the current supply rate on the basis of the driving power source voltage and the environmental temperature of the electrical load irrespective of the temperature increase of the electrical load caused by the current supply load current.

8. The non-feedback type load current controller according to claim 7, wherein the non-volatile program memory further contains a program serving as a selection switching unit and a permissible error width correcting unit, and wherein the selection switching unit invalidates the abnormality judging and correcting unit during a predetermined period after the operation is started, and the permissible error width correcting unit sets a permissible error width in the abnormality judgment band comparison to a large value when the abnormality judging and correcting unit is invalid, and corrects the permissible error width so that the permissible error width concerned is narrowed after the abnormality judging and correcting unit is validated.

9. The non-feedback type load current controller according to claim 6, wherein the non-volatile program memory further a program serving as a load temperature increase estimating unit and a corrected current supply rate calculating unit, and wherein the load temperature increase estimating unit estimates the present temperature increase value of the electrical load in association with a current supply past record to the electrical load and the thermal time constant of the electrical load, and adds the temperature increase value thus estimated with the environmental temperature detected by the temperature sensor to calculate the present temperature of the electrical load, and the corrected current supply rate calculating unit increasingly or decreasingly corrects the proper current supply rate calculated in the proper current supply rate calculating unit in connection with increase or decrease of the temperature increase of the load estimated by the load temperature increase estimating unit.

10. The non-feedback type load current controller according to claim 9, wherein the non-volatile program memory further contains a program serving as a selection switching unit and a permissible error width correcting unit, the selection switching unit invalidates the corrected current supply rate calculating unit during a predetermined period after the operation is started, and the permissible error width correcting unit sets the permissible error width in the abnormality judgment band comparison to a large value when the corrected current supply rate calculating unit is invalidated, and corrects the permissible error width concerned so that the permissible error width concerned is narrowed after the corrected current supply rate calculating unit is invalidated.

11. The non-feedback type load current controller according to claim 7, wherein the load temperature increase estimating unit estimates the present temperature increase value added with the thermal time constant of the electrical load by a first-in first-out data table for periodically storing the square representative value of the set voltage corresponding to the supply target current to the electrical load or the monitoring voltage over at least a period above the thermal time constant of the electrical load, and a calculating unit for calculating a moving average value concerning plural data stored in the data table and multiplying the moving average value by a temperature conversion coefficient.

12. The non-feedback type load current controller according to claim 1, wherein the non-volatile program memory further contains a program serving as a comparison target voltage setting unit, the comparison target voltage setting unit operates upon input of a voltage proportional to the supply target current to the electrical load, and generates a comparison target voltage having a response delay corresponding to the smoothening time constant of a smoothening capacitor in the current detecting amplifying circuit portion, and the smoothening time constant of the smoothening capacitor corresponds to the current time constant that is the ratio between the inductance and resistance value of the electrical load.

13. The non-feedback type load current controller according to claim 6, wherein the electrical load is each of plural electromagnetic-valve driving electromagnetic solenoids for a shift gear switching electromagnetic valve in a multistage automatic transmission for a vehicle, the supply target current to the electromagnetic solenoids is varied in magnitude in accordance with driving initial current and operation holding current, and the temperature sensor for detecting the environmental temperature of the electromagnetic solenoids is substituted by an oil temperature sensor for detecting the temperature of lubricating oil of the automatic transmission.