Showing papers on "H bridge published in 1989"

Self-check method of four-wheel steering drive system

Abstract: In a self-check method of a four-wheel steering drive system, a relay downstream current upon ON/OFF of a relay is checked to check a state of said relay. Forward and reverse rotation control signals of a duty ratio of 0% are supplied to a predetermined combination of switching elements constituting an H bridge circuit to check if a current obtained from the predetermined combination of switching elements is an overcurrent, thereby checking a state of the H bridge circuit. When the rear wheels are turned to a target rear wheel position with reference to a present rear-wheel position, whether or not a difference between the target rear-wheel position and an actual rear-wheel position is set to be a predetermined value or less within a predetermined period of time is checked, thereby checking a state of a steering motor and a rear-wheel steering mechanism.

H-bridge protective circuit

Abstract: PURPOSE:To prevent the breakdown of an H-bridge circuit by turning OFF a power transistor through causing Zener diodes and transistors to operate at high speed by means of the surge voltage of a power source. CONSTITUTION:The forward and reverse rotation of a magnet motor 12 is conducted by an H-bridge circuit composed of transistors 4-7 according to a command from a command generator 15. A sensor 13 detects the position of said magnet motor, and a control circuit 14 compares said position with the command to control the position. A signal is applied to terminals a, a' at the time of forward rotation and to terminals b, b' at the time of reverse rotation. Diodes 16, 17, 18 and 43, 44, 50 constitute an inhibit circuit, and an overvoltage protective circuit is composed of resistances 29, 35, Zener diodes 51, 52 and transistors 53, 54 to cut OFF the base of said transistors 5, 7 at the time of applying a surge. Also, a resistance 32 turns ON said transistors 53, 54 and OFF said transistors 5, 7 at the time when an overcurrent flows, to protect these transistors.

Controlling method for four-wheel steering device

Abstract: PURPOSE:To prevent hunting due to inertia of a motor, in a motor driving device which performs PWM control, by forming a circuit which shortcircuits its motor while a PWM signal during the PWM control is off so as to afford braking force to a motor. CONSTITUTION:In a motor driving device fit for an electric power steering device and the like, a general H bridge circuit for controlling its motor has respective transistors Tr 1, 3 and 2, 4 in the lower and upper sides thereof and a motor 5. In this case, Tr 2 is a made to be on during the period when the Tr 1 is off, while the Tr 4 is made to be constantly on as usual. Regenerative electric current is thereby guided to pass through the motor 5 during the period when the Tzr 1 is off, then dynamic braking electric current is guided to pass therethrough to make it possible to brake the motor 5. Respective signals sent to the gate terminals TM 1-TM 4 of the Tr 1-Tr 4 are generated from a logic circuit or a microcomputer.

Analog multplex for detecting magnitude and sense of current flowing through h-bridge stage by using single detection resistor

Abstract: PURPOSE: To accurately detect the magnitude and sense of current by providing a multiplexer with a single detecting resistor connected between the common virtual ground node of a drive bridge circuit and the real ground node. CONSTITUTION: An H-bridge stage for driving induction load L is composed of four switches SW1-SW4 driven by drive signals IN1 and inversion signals, and it switches the load functionally as the function of a duty cycle. The control of the load L is performed by detecting the magnitude and the sense (direction) of the current flowing through the load L. Moreover, an analog multiplex MPX made of two switches SWA and SWB adds this output signal to the next converter C. Then, the output amplitude of this MPX is proportionate to the quantity of a current flowing through the load L, and this polarity is decided by the polarity of the voltage Vref added to the other output of that comparator C.