Driving control device of brushless motor

1. A driving control device of a brushless motor comprising:

an inverter circuit having: First arm-side switching elements that are connected between respective phases of respective armature coils of the brushless motor and one terminal of a power supply; and second arm-side switching elements that are connected between respective phases of the respective armature coils and the other terminal of the power supply, and a control unit, wherein when electric power from the power supply is not detected, a short-circuit braking according to a short-circuit breaking signal is performed to brake the brushless motor, and wherein, in the short-circuit braking, the control unit outputs a signal of turning off all the first arm-side switching elements and outputs a signal of controlling at least one of the second arm-side switching elements to perform a switching operation, in which the at least one of the second arm-side switching elements is repeatedly switched, and turning on the other second arm-side switching elements.

2. The driving control device of a brushless motor according to claim 1 ,

wherein the control unit further comprises:

a motor control unit that outputs a driving control signal;

a short-circuit braking unit that that outputs the short-circuit braking signal, and

a control-operation changeover unit that operates the motor control unit when power feed of the power supply is detected, and operates the short-circuit braking unit when the power feed of the power supply is not detected.

3. The driving control device of a brushless motor according to claim 2 ,

wherein the control-operation changeover unit comprises:

a power supply voltage monitoring unit that detects the power feed from the power supply, and

a control operation determination unit that detects the power feed of the power supply and operates the motor control unit or short-circuit braking unit.

4. The driving control device of a brushless motor according to claim 2 ,

wherein the short-circuit braking unit outputs a switching signal having a frequency, which is increased as time passes, to the at least one of the second arm-side switching elements and controls the at least one of the second arm-side switching elements to perform the switching operation.

5. The driving control device of a brushless motor according to claim 2 ,

wherein the short-circuit braking unit outputs a switching signal having a duty ratio, which is increased as time passes, to the at least one of the second arm-side switching elements and controls the at least one of the second arm-side switching elements to perform the switching operation.

6. The driving control device of a brushless motor according to claim 1 ,

wherein the brushless motor is a three-phase motor,

wherein the first arm-side switching elements and the second arm-side switching elements are respectively connected to the respective armature coils of three phases, and

wherein the control unit outputs a signal of turning off the first arm-side switching elements of a U-phase, a V-phase and a W-phase and outputs a signal of controlling the second arm-side switching element of at least one phase to perform the switching operation and turning on the second arm-side switching elements of the other two phases.