Half-bridge converter comprising a bootstrap circuit to provide a negative turn-off voltage

Patent metadata

Field	Value
Publication number	US-12506396-B2
Application number	US-202418401740-A
Country	US
Kind code	B2
Filing date	Jan 2, 2024
Priority date	Jan 5, 2023
Publication date	Dec 23, 2025
Grant date	Dec 23, 2025

Abstract

A half-bridge converter includes a high-side transistor connected to a positive electrode of a direct current (DC) voltage source and a low-side transistor connected to a reference ground. A gate driver is configured to control the high-side and low-side transistors at a duty cycle of a gate driver control signal. A bootstrap circuit is configured to provide a positive voltage and a negative voltage to the gate driver for the high-side transistor. The bootstrap circuit comprises a first diode, a first capacitor and a Cuk converter. The Cuk converter comprises a first and a second inductor, a switch, a first and a second capacitor and a second diode to output the negative voltage to the high-side transistor gate driver. The Cuk converter is configured to output the negative voltage when operating in a Discontinuous Voltage Mode (DVM).

First claim

What is claimed is:

1 . A half-bridge converter, comprising:
a high-side transistor connected to a positive electrode of a direct current (DC) voltage source; a low-side transistor connected to a reference ground; a gate driver configured to control the high-side and low-side transistors at a duty cycle of a gate driver control signal; and a bootstrap circuit configured to provide a positive voltage and a negative voltage to the gate driver for the high-side transistor, the bootstrap circuit comprising a first diode, a first capacitor and a Cuk converter, the Cuk converter comprising a first and a second inductor, a switch, a first and a second capacitor and a second diode to output the negative voltage to the high-side transistor gate driver, wherein a value of inductance of the first and second inductors and a value of capacitance of the first capacitor of the Cuk converter are set such that the Cuk converter is configured to output the negative voltage when operating in a Discontinuous Voltage Mode (DVM).

2 . The half-bridge converter according to claim 1 , wherein a ratio of the negative voltage to the positive voltage when the Cuk converter operates in DVM is expressed by the following equation:

V
-

V
+

=

-

2
⁢
R
⁢
C
⁢
f

1
-
D

where R is load resistance, C is a capacitance of the first capacitor of the Cuk converter, f is switching frequency and D is the duty cycle of the gate driver control signal.

3 . The half-bridge converter according to claim 1 , configured such that the Cuk converter when operating uses the high-side transistor as the switch.

4 . The half-bridge converter of claim 1 , further comprising an additional diode arranged to protect the bootstrap circuit from a voltage of a low side gate supply voltage source.

5 . The half-bridge converter according to claim 1 , further comprising a resistor connected in series with the first inductor of the Cuk converter, a value of resistance being above 100Ω.

6 . The half-bridge converter according to claim 1 , further comprising a Zener diode disposed in parallel to the second capacitor of the Cuk converter to limit an amplitude of the negative voltage.

Assignees

• Etel Sa

Inventors

• Zimoch Piotr

Classifications

• H02M3/158

  including plural semiconductor devices as final control devices for a single load · CPC title

• H03K2217/0072

  Low side switches, i.e. the lower potential [DC] or neutral wire [AC] being directly connected to the switch and not via the load · CPC title

• H03K2217/0063

  High side switches, i.e. the higher potential [DC] or life wire [AC] being directly connected to the switch and not via the load · CPC title

• H03K17/063 Primary

  in field-effect transistor switches · CPC title

• H02M3/005

  using Cuk converters · CPC title