US 6,545,513 B2Granted

Electric load drive apparatus

AssigneeDenso Corporation

InventorsMasahiro Tsuchida, Nobumasa Ueda, Hiroshi Fujimoto, Yoshiki Koyama

Life of this patent

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Abstract

A current control circuit controls a gate potential of a transistor to equalize a load current IL with a trapezoidal wave signal Sb. The trapezoidal wave signal Sb increases at a constant gradient when a drive command signal Sa turns into H level. Due to increase of load current IL, the transistor starts operating in a linear region and a gate voltage VGS abruptly increases. A saturation state detecting circuit turns a current saturation signal Sc into L level when the gate voltage VGS exceeds a reference voltage Vr. A trapezoidal wave generating circuit stops increase of trapezoidal wave signal Sb. When drive command signal Sa turns into L level, the trapezoidal wave signal Sb decreases at a constant gradient. The load current IL decreases according to reduction of trapezoidal wave signal Sb.

Claims25

Dependent claims

An electric load drive apparatus comprising:

a switching element provided in an electric power supply path extending from a direct-current power source to an electric load;
a detecting resistor, connected in series with said switching element, for detecting a voltage value representing a load current flowing across said electric load via said switching element;
a saturation state detecting section for outputting a current saturation signal during a term an upper limit current flows across said electric load, said upper limit current being a maximum current flowable via said switching element in an open/close controllable range of said switching element;
a signal generating section for producing a trapezoidal wave signal whose voltage value starts changing in accordance with increase of said load current when a drive start command signal is entered, stops changing in response to the output of said current saturation signal generated from said saturation state detecting section, and then starts changing in accordance with decrease of said load current when a drive stop command signal is entered, and
a current control section for comparing said trapezoidal wave signal produced from said signal generating section with said voltage value detected by said detecting resistor and then controlling said switching element based on said trapezoidal wave signal in such a manner a trapezoidal wave current flows across said electric load.

2 more elements

A control apparatus for a power MOS transistor comprising:

a power MOS transistor interposed between an electric load and a power source for causing a trapezoidal pulse current to flow across said electric load when a control voltage is applied to a gate terminal of said power MOS transistor;
a gate-source voltage detecting section for detecting a gate-source voltage of said power MOS transistor when said control voltage is applied to the gate terminal of said power MOS transistor;
a feedback section for obtaining deviations of rise time and fall time of a present load current waveform with respect to their target values based on the gate-source voltage of said power MOS transistor detected by said gate-source voltage detecting section, and for performing feedback control of said power MOS transistor so as to eliminate said deviations of rise time and fall time.

An electric load drive apparatus comprising:

a signal generating section for generating a current command signal in accordance with a drive command signal entered from an external device, said current command signal having a trapezoidal waveform increasing from a first level to a second level in response to a drive start command and decreasing from the second level to the first level in response to a drive stop command;
a current drive section, provided in a current supply path extending from a direct-current power source to an electric load, for detecting a load current flowing across said electric load and outputting a trapezoidal current to said electric load based on a comparison between the detected load current and said current command signal;
a measuring section for measuring a rise time of said load current corresponding to increase of said current command signal and a fall time of said load current corresponding to decrease of said current command signal;
and
a gradient control section for controlling a change rate of said current command signal produced from said signal generating section in such a manner that the measured rise time is equalized with a predetermined reference rise time and the measured fall time is equalized with a predetermined reference fall time.

2 more elements

An electric load drive apparatus comprising:

a transistor provided in a current path extending from a direct-current power source to an electric load for controlling a load current flowing across said electric load based on a control signal;
a current detecting section for detecting the load current flowing across said electric load;
a signal generating section for generating a current command signal in accordance with a drive command signal entered from an external device, said current command signal having a trapezoidal waveform increasing from a first level to a second level in response to a drive start command and decreasing from the second level to the first level in response to a drive stop command;
a current control section for supplying said control signal based on a comparison between a current detection signal detected by said current detecting section and said current command signal in such a manner that a trapezoidal current flows across said electric load in accordance with said current command signal;
and
a control voltage limit section for limiting said control signal to a decreasing start level in response to said drive stop command, said decreasing start level being slightly higher than a threshold level of said transistor required to reduce the current flowing across said electric load.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/146,741Filed 16 May 2002
Priority: JP 2001-14771417 May 2001
Published: US 2002/0171455 A121 Nov 2002
Granted: 8 Apr 2003
Term ends: Not estimatedThe source records don’t support an estimate.

Classification4 codes

H03K 4/94
Generating pulses having essentially a finite slope or stepped portions: having trapezoidal shape
H03K 17/04206
By feedback from the output circuit to the control circuit: in field-effect transistor switches
H03K 17/166
By feedback from the output circuit to the control circuit: soft switching
H03K
Pulse technique