Inductive load driving method and H-bridge circuit control device

An H-bridge circuit control device for controlling an H-bridge circuit which includes a plurality of semiconductor switching elements and a plurality of flywheel diodes respectively connected in parallel to said plurality of semiconductor switching elements, said H-bridge circuit supplying electric current to said inductive load in both forward and reverse directions, said device comprising:

• (a) control signal generating means for generating a control signal having a predetermined frequency;
• (b) control means for turning-on at least two of said plurality of semiconductor switching elements in accordance with said control signal to cause said electric current to flow through said inductive load;
• (c) a current detecting resistor connected to said H-bridge circuit so as to detect the electric current flowing from a power source through said inductive load and not to detect the electric current flowing through said inductive load to the power source, thereby obtaining a detection voltage;
• (d) a variable reference voltage generating circuit for decreasing a variable reference voltage in a condition where said electric current flowing through said inductive load should be decreased;
• and
• (e) comparing means for comparing the detection voltage with the variable reference voltage, wherein:
• said control means cuts-off said at least two semiconductor switching elements when the detection voltage is larger than the variable reference voltage so that electric energy accumulated in said inductive load is consumed.