U.S. patent application number 16/042541 was filed with the patent office on 2020-01-23 for gate driver power supply.
This patent application is currently assigned to BAE Systems Controls Inc.. The applicant listed for this patent is BAE Systems Controls Inc.. Invention is credited to Paul Carvell.
Application Number | 20200028497 16/042541 |
Document ID | / |
Family ID | 69057633 |
Filed Date | 2020-01-23 |
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United States Patent
Application |
20200028497 |
Kind Code |
A1 |
Carvell; Paul |
January 23, 2020 |
GATE DRIVER POWER SUPPLY
Abstract
A power supply for a gate driver circuit is provided. The power
supply is configured to supply a logic voltage, a positive voltage
and a negative voltage to the gate driver circuit such that a gated
semiconductor driven by the gate driver circuit does not
inadvertently turn on. The gate driver power supply is configured
such that the logic voltage becomes a steady-state voltage prior to
the positive voltage becoming a steady-state voltage and remains
above a first voltage value until the positive voltage is less than
a second voltage value.
Inventors: |
Carvell; Paul; (Owego,
NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BAE Systems Controls Inc. |
Endicott |
NY |
US |
|
|
Assignee: |
BAE Systems Controls Inc.
Endicott
NY
|
Family ID: |
69057633 |
Appl. No.: |
16/042541 |
Filed: |
July 23, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H03K 3/017 20130101;
H03K 2017/066 20130101; H03K 17/08122 20130101; H03K 17/063
20130101; H03K 2217/0081 20130101; H03K 17/08 20130101 |
International
Class: |
H03K 3/017 20060101
H03K003/017; H03K 17/08 20060101 H03K017/08 |
Claims
1. A gate driver power supply for outputting a positive voltage, a
negative voltage and a logic voltage, the gate driver power supply
comprising: a power source coupled to a primary winding of a
transformer via at least two complementary switches; a full bridge
rectifier coupled to a secondary winding of the transformer; a
first shunt regulating circuit coupled to a logic supply line and
the full bridge rectifier; a series linear regulating circuit
coupled to the logic supply line, the first shunt regulating
circuit and the full bridge rectifier, the first shunt regulating
circuit and the series linear regulating circuit regulating the
logic voltage on the logic supply line; a second shunt regulating
circuit coupled to the full bridge rectifier, a ground and a
positive voltage line; and a diode having a first terminal coupled
to the logic supply line and a second terminal coupled to a
negative supply line.
2. The gate driver power supply of claim 1, wherein the series
linear regulating circuit comprises a transistor, a first resistive
divider and a MOSFET or a bipolar junction transistor (BJT), the
base of the transistor is coupled to the logic supply line, the
collector of the transistor is coupled to the gate of the MOSFET or
base of the BJT, and wherein the source of the MOSFET or the
emitter of the BJT is coupled to the logic supply line.
3. The gate driver power supply of claim 2, further comprising a
first capacitor coupled to output terminals of the full bridge
rectifier.
4. The gate driver power supply of claim 3, wherein the first shunt
regulating circuit comprises a first shunt regulator, a second
resistive divider and a second capacitor, the cathode of the first
shunt regulator being coupled to the emitter of the transistor, the
anode of the first shunt regulator coupled to the negative supply
line, the first capacitor and full bridge rectifier, the second
resistive divider comprising a first resistor and a second resistor
connected in series, the first resistor having a first end and a
second end, the second resistor having a third end and a fourth
end, the first end being coupled to the logic supply line, the
second end being coupled to the reference terminal of the first
shunt regulator and the third end of the second resistor, the third
end of the second resistor further being coupled to the reference
terminal of the first shunt regulator and the fourth end being
coupled to the negative supply line, the second capacitor being
coupled to the logic supply line and the negative supply line.
5. The gate driver power supply of claim 4, wherein the first
resistive divider comprises a third resistor and a fourth resistor
is series, the third resistor having a fifth end and a sixth end,
the fourth resistor having a seventh end and an eighth end, the
fourth end being coupled to the positive supply line, the first
capacitor and full bridge rectifier, the fifth end being coupled to
the drain of the MOSFET or the collector of the BJT and the seventh
end of the fourth, the seventh end of the fourth resistor further
being coupled to the drain of the MOSFET or collector of the BJT
and the eighth end being coupled to the gate of the MOSFET or base
of the BJT and collector of the transistor.
6. The gate driver power supply of claim 1, wherein the diode is a
Zener diode.
7. The gate driver power supply of claim 1, further comprising a
surge suppression circuit coupled to the positive voltage line and
the negative voltage line.
8. The gate driver power supply of claim 1, wherein the series
linear regulating circuit is configured such that the logic voltage
becomes a steady-state voltage prior to the positive voltage
becoming a steady-state voltage.
9. The gate driver power supply of claim 1, wherein the gate driver
power supply is configured such that the logic voltage remains
above a first voltage value until the positive voltage is less than
a second voltage value.
10. The gate driver power supply of claim 5, wherein the second
shunt regulating circuit comprises a second shunt regulator, a
third resistive divider and a third capacitor, the cathode of the
second shunt regulator being coupled to the positive supply line,
the anode of the second shunt regulator coupled to the ground, the
third resistive divider comprising a fifth resistor and a sixth
resistor connected in series, the fifth resistor having a ninth end
and a tenth end, the sixth resistor having a eleventh end and a
twelfth end, the ninth end being coupled to the positive supply
line, the tenth end being coupled to the reference terminal of the
second shunt regulator and the eleventh end of the sixth resistor,
the eleventh end of the second resistor further being coupled to
the reference terminal of the second shunt regulator and the
twelfth end being coupled to the ground, the third capacitor being
coupled to the positive supply line and the ground.
11. The gate driver power supply of claim 5, wherein the gate
driver power supply further outputs a boost voltage.
12. The gate driver power supply of claim 1, wherein the secondary
winding of the transformer comprises a first winding and a second
winding, and wherein the gate driver power supply further comprises
a boost voltage generating circuit, the boost voltage generating
circuit comprising the second winding, a second diode coupled to
the second coil and a capacitor.
13. The gate driver power supply of claim 1, wherein the primary
winding of the transformer comprises a first winding and a second
winding, the first winding and the second winding having opposite
polarity.
14. The gate driver power supply of claim 11, wherein the gate
driver power supply supplies power to a gate driver circuit, the
gate driver circuit comprising a driver, a first gated
semiconductor and a second gated semiconductor, the first gated
semiconductor and the second gated semiconductor being connected in
series, a gate of the first gated semiconductor being coupled to a
first gate pin of the driver, a gate of the second gated
semiconductor being coupled to a second gate pin of the driver,
wherein the logic voltage is coupled to a V.sub.DD pin of the
driver, the positive voltage is coupled to a drain of the first
gated semiconductor and the negative voltage is coupled to the
source of the second gated semiconductor.
15. The gate driver power supply of claim 11, wherein the boost
voltage is coupled to a bootstrap pin of the driver.
16. The gate driver power supply of claim 15, wherein when the gate
driver circuit is powered by the gate driver power supply, the gate
driver circuit is configured to charge a gate of a gated
semiconductor by switching the first gated semiconductor on and the
second gated semiconductor r off and discharge the gate of the
gated semiconductor by switching the second gated semiconductor on
and the first gated semiconductor off.
Description
FIELD OF THE DISCLOSURE
[0001] This disclosure relates to electronic circuits. More
specifically, this disclosure relates to a power supply for a gate
driver circuit.
BACKGROUND
[0002] A gate driver circuit is used to charge a gate of a
semiconductor, such as a gated semiconductor. Gated semiconductors
include an insulated-gate bipolar transistor (IGBT) and metal-oxide
semiconductor field-effect transistor (MOSFET). A gate driver
circuit uses a dedicated power source to amplify a signal, such as
a pulse-width modulation (PWM) signal in order to control a gated
semiconductor via its gate.
[0003] A typical dedicated power source for the gate driver circuit
will provide a working voltage, e.g., logic voltage and positive
voltage and negative voltage. The values of the same over time are
important to the performances of the gate driver circuit and the
gated semiconductor being driven. For example, depending on the
values of the respective voltages at a given time, the gated
semiconductor might inadvertently turn on.
SUMMARY
[0004] Accordingly, disclosed is a power supply for a gate driver
circuit configured to supply a logic voltage, positive voltage and
a negative voltage to the gate driver circuit such that a gated
semiconductor driven by the gate driver circuit does not
inadvertently turn on, especially during power up.
[0005] In another aspect of the disclosure, the power supply for a
gate driver circuit is further configured to supply a boost voltage
to the gate driver circuit.
[0006] The gate driver power supply comprises a power source, a
full bridge rectifier, a series linear regulating circuit, a first
shunt regulating circuit, a second shunt regulating circuit and a
diode. The power source is coupled to a primary winding of a
transformer via at least two complementary switches. The full
bridge rectifier is coupled to a secondary winding of the
transformer. The first shunt regulating circuit is coupled to a
logic supply line and the full bridge rectifier. The series linear
regulating circuit is coupled to the logic supply line, the first
shunt regulating circuit and the full bridge rectifier. The first
shunt regulating circuit and the series linear regulating circuit
regulates the logic voltage on the logic supply line. The second
shunt regulating circuit is coupled to the full bridge rectifier, a
ground and a positive voltage line. The diode has a first terminal
coupled to the logic supply line and a second terminal coupled to a
negative supply line.
[0007] The series linear regulating circuit comprises a transistor,
a first resistive divider and a MOSFET or a bipolar junction
transistor (BJT). The base of the transistor is coupled to the
logic supply line, and the collector of the transistor is coupled
to the gate of the MOSFET or base of the BJT. The source of the
MOSFET or emitter of the BJT is coupled to the logic supply
line.
[0008] The series linear regulating circuit is configured such that
the logic voltage becomes a steady-state voltage prior to the
positive voltage becoming a steady-state voltage.
[0009] The gate driver power supply is configured such that the
logic voltage remains above a first voltage value until the
positive voltage is less than a second voltage value.
DRAWINGS
[0010] FIG. 1 is a block diagram of certain components of a gate
driver power supply in accordance with aspects of the
disclosure;
[0011] FIG. 2 is a schematic diagram of an example of a gate driver
power supply in accordance with aspects of the disclosure;
[0012] FIG. 3 is a schematic diagram of a gate driver power supply
used in a simulation;
[0013] FIG. 4 illustrates the simulation results for the circuit in
FIG. 3 includes showing a logic voltage, positive voltage and
negative voltage over time; and
[0014] FIG. 5 illustrates a diagram showing a logic voltage, a
positive voltage, a negative voltage and boost voltage coupled to a
portion of an example of a gate driver circuit in accordance with
aspects of the disclosure.
DETAILED DESCRIPTION
[0015] FIG. 1 is a block diagram of certain components of a gate
driver power supply 1 in accordance with aspects of the disclosure.
The gate driver power supply 1 is a DC to DC converter converting
an input DC voltage into more than one DC output voltages. In
aspects of the disclosure, the gate driver power supply 1 may
output a logic voltage, a positive voltage and a negative voltage.
Where needed, the gate driver power supply 1 may also output a
boost voltage. The boost voltage may be used where a gate driver
circuit is driving a large semiconductor device. Therefore, the
boost voltage circuit 20 depicted in FIG. 1 is optional.
[0016] The gate driver power supply 1 comprises a switching power
supply 10, a full bridge rectifier 30, a smoothing capacitor 32, a
series linear regulating circuit 40 (pull-down circuit), a logic
line shunt regulating circuit 35, a positive line shunt regulating
circuit 45, a negative line regulating circuit 50 and surge
protection and filtering 55.
[0017] Each of the above-blocks will be described with reference to
an example of the gate driver power supply 1 in accordance with
aspects of the disclosure, which is depicted in FIG. 2.
[0018] The switching power supply 10 comprises an input voltage
(V2). The input voltage (V2) is a DC voltage. The switching power
supply 10 further comprises two switches, e.g., MOSFETS M1 and M2.
The MOSFETS are biased to be in the switching region of operation.
Other types of switches may be used to achieve the switching. The
switching operates in a complimentary fashion, where when M1 is
turned ON M2 is turned OFF and vice versa. However, both M1 and M2
may be OFF. The switching is controlled by inputs into the gates of
M1 and M2. A voltage V3 is supplied to the gate of M1 and a voltage
V2 is supplied to the gate of M2. The voltages V2 and V3 are pulsed
on/off at a preset duty cycle.
[0019] In other aspects of the disclosure, more than two switches
may be used. For example, one or both of M1 and M2 may be replaced
with a group of switches in parallel. For example, multiple MOSFETS
may be connected in parallel where the same drive signal into the
gates is used so that the switches would turn ON and OFF at the
same time. The drains of each MOSFET would be all connected
together. Additionally, the sources of each MOSFET would be all
connected together. In an aspect of the disclosure, a respective
gate resistor may connect to the gate of each MOSFET in series. The
resistance value of each respective gate resistor may be the same.
For example, a 10.OMEGA. resistor may be used.
[0020] The switching power supply 10 further comprises a power
transformer (e.g., L1-L4). The primary side of the transformer
comprises two coils L1 and L4. The coils have opposite polarity. L1
is coupled to one of the switches, e.g., M2 and L4 is coupled to
the other of the switches, e.g. M1. In an aspect of the disclosure,
the inductance of the primary windings is the same.
[0021] The switching power supply 10 further comprises snubber
circuits for suppression of transients which result from the
switching of M1 and M2. R14 and C8 form one snubber circuit across
M1 and R16 and C7 form another snubber circuit across M2. In an
aspect of the disclosure, the resistance values for R14 and R16 are
the same and the values of the capacitors are the same.
[0022] The switching power supply 10 further comprises additions
snubber circuits or clamping circuits for suppression of voltage
spikes causes of leakage inductances L1 and L4, primary windings.
For example, diodes in combination with a resistor and capacitor
may be used. The diode may be a Schottky rectifier diode. As
depicted in FIG. 2, D9, R6 and C5 provide one snubber or clamping
circuit for L1 and D8, R6 and C5 form another snubber or clamping
circuit for L4. In an aspect of the disclosure, the same diode may
be used for both D8 and D9.
[0023] The power transformer has at least one secondary winding,
e.g., L2. When a boost voltage is needed, a second secondary
winding is included (as shown in FIG. 2, e.g., L3). The ratio of
primary windings to second windings is set based on the required
output voltages and the input voltage.
[0024] The switching power supply 10 provides an AC voltage. The
power supply 1 further comprises a full bridge rectifier 30 and
smoothing capacitor 32 (shown in FIG. 2 as C6). The voltage is
rectified by the full bridge rectifier 30 and smoothed to provide a
DC voltage to the remaining components of the power supply 1. The
full bridge rectifier 30 may comprise four Schottky rectifier
diodes (e.g., D3-D6). The capacitor 32 removes the pulsating effect
and a smooth DC voltage is obtained.
[0025] The power supply 1 further comprises a series linear
regulating circuit 40. The series linear regulating circuit 40
allows the logic voltage to rise to a steady state value (nominal
value) before the positive voltage may rise to its steady state
value (nominal value). In other words, during turn on of the power
supply 1, the logic rapidly charges. Additionally, during turn off,
the series linear regulating circuit 40 maintains the logic supply
voltage above a voltage level whereas the positive voltage value is
reduced to below another voltage level.
[0026] The series linear regulating circuit 40 comprises a resistor
dividing network (resistor bridge), e.g., R2 and R12, a MOSFET,
e.g., M3 and a transistor Q1. The MOSFET may be an N-channel
MOSFET. One of the resistors, e.g., R2 is connected to the positive
line (rail). The same resistor is connected to the drain of M3. The
source of M3 is connected to the logic line (rail). Another of the
resistors, e.g., R12, is connected to the drain of M3 as well as
the gate of M3. The resistance of R12 is larger than the resistance
of R2.
[0027] In an aspect of the disclosure, the MOSFET M3 is operated in
the linear region. When a voltage builds' up at the gate of M3,
proportional current is conducted through M3.
[0028] For example, current flows through resistors R2 and R12.
Since R12 has a larger resistance than R2, voltage slowly builds up
at the gate of the MOSFET M3. As a voltage is established at the
gate, a small current can flow across MOSFET M3. As the voltage
becomes larger, more current can flow across MOSFET M3. In another
aspect of the disclosure, MOSFET M3 may be replaced with a bipolar
junction transistor BJT.
[0029] The transistor Q1 may be a NPN bipolar junction transistor
BJT. The base of transistor Q1 is connected to the logic line and
the source of MOSFET M3 (as well as the logic line shunt regulating
circuit 35) which will be described later. The collector of
transistor Q1 is connected to resistor R12. The transistor Q1 is
operating in the active region and acts as an amplifier. Thus,
transistor Q1 operates as the feedback component of the series
linear regulating circuit 40 which causes the logic voltage to
remain stable.
[0030] For example, as the current into the base increases, more
current can flow across the transistor Q1, e.g., from the collector
to the emitter. This causes the voltage at the gate of MOSFET M3 to
droop, which is turn lowers the current flowing across M3.
[0031] The resistance R2 is selected to allow current to flow
quickly into the series linear regulating circuit 40.
[0032] The power supply 1 further comprises a logic line shunt
regulating circuit 35. The logic line shunt regulating circuit 35
in conjunction with the series linear regulating circuit 40
controls the logic voltage. The logic line shunt regulating circuit
35 comprises an adjustable precision shunt regulator such as a
TL431. The adjustable precision shunt regulator is connected to a
resistor dividing network (resistor bridge), e.g., R4 and R5. The
voltage at the cathode is proportional to the ratio of resistors
R4/R5. Resistor R4 is connected to the logic line and connected to
the reference terminal. Resistor R5 is connected to the reference
terminal and the negative line. The cathode of the adjustable
precision shunt regulator is connected to the emitter of transistor
Q1. The anode of the adjustable precision shunt regulator is
connected to the negative line.
[0033] The adjustable precision shunt regulator allows the current
flowing across the same to varying to maintain the voltage at the
logic line. For example, the emitter current I.sub.E, is a sum of
the base current I.sub.B and the collector I.sub.c. Since, the
adjustable precision shunt regulator is coupled to the emitter of
the transistor Q1, the emitter current I.sub.E is seen at the
cathode. Thus, the current flowing to the negative line changes as
the emitter current changes, but the voltage at the logic line is
maintained.
[0034] A capacitor C1 is connected between the logic line and the
negative line for stability and buffering.
[0035] The power supply 1 further comprises a positive line shunt
regulating circuit 45. The positive line shunt regulating circuit
45 regulates the positive voltage on the positive line. The
positive line shunt regulating circuit 45 is similar to the logic
line shunt regulating circuit 35 in that it comprises an adjustable
precision shunt regulator such as a TL431. The adjustable precision
shunt regulator is connected to a resistor dividing network
(resistor bridge), e.g., R7 and R8. The voltage at the cathode is
proportional to the ratio of resistors R7/R8 (regulated output
voltage). Resistor R7 is connected to the positive line and
connected to the reference terminal. Resistor R8 is connected to
the reference terminal and to ground. The anode of the adjustable
precision shunt regulator is connected to ground.
[0036] A capacitor C2 is connected between the positive line and
ground for stability and buffering.
[0037] While FIG. 2 shows a resistance R13 feeding the positive
line shunt regulating circuit 45, this resistance value may
represent the internal resistance of the circuit board or
traces.
[0038] The power supply 1 further comprises a negative line
regulating circuit 50. The negative line regulating circuit 50
comprises a diode D2 and a resistor R1. As depicted, the diode D2
is a Schottky rectifier diode. The logic line feeds the negative
line via diode D2 so that the negative lines effectively track the
logic line. In another aspect of the disclosure, D2 may be a Zener
diode. By using a Zener diode, the maximum negative voltage may be
clamped to a specific value. In this configuration, the diode is
reversed biased due to the higher voltage appearing on the logic
than on the negative line.
[0039] In an aspect of the disclosure, the power supply 1 further
comprises boost voltage circuit 20. The boost voltage circuit 20
comprises a half bridge rectifier, a resistor R15 and a capacitor
C2. The half bridge rectifier comprises a diode D7. The half bridge
rectifier is coupled to the secondary winding of the transformer,
e.g., L3. The half bridge rectifier receives an AC voltage and
converts the same to a DC voltage. Capacitor C3 acts as a smooth
capacitor.
[0040] The boost voltage is referenced to the positive line.
[0041] The logic line is coupled to ground via a diode D1 and
resistor R11. As depicted in FIG. 2, the diode D1 is a Schottky
rectifier diode.
[0042] The power supply 1 further comprises surge protection and
filtering 55. The surge protection and filtering 55 is provided by
a plurality of resistors (e.g., R3, R9 and R10) and a capacitor
(e.g., C4). Resistor R3 is connected between the positive line and
ground. Resistor R9 is connected between the positive line and the
negative line. Resistor R10 is connected between the negative line
and ground and in parallel to capacitor C4.
[0043] An example of the gate driver power supply 1 was simulated
in pspice. FIG. 3 depicts the example of the gate driver power
supply 1 which was simulated.
[0044] The input voltage V2 was 19V. 1 m.OMEGA. was used for R13.
The following parameters were used for the pulsed signal V1 as
shown on the below left of FIG. 3.
[0045] Initial Voltage=0V
[0046] Von=10V
[0047] Time delay=1.0001 ms
[0048] Time Rise=100 ns
[0049] Time Fall=100 ns
[0050] Time On=4.8 .mu.s
[0051] Time period=10.mu.
[0052] Number of Cycles=1200.
[0053] The following parameters were used for the pulsed signal V3
as shown on the below left of FIG. 3.
[0054] Initial Voltage=0V
[0055] Von=10V
[0056] Time delay=1.0051 ms
[0057] Time Rise=100 ns
[0058] Time Fall=100 ns
[0059] Time On=4.8 .mu.s
[0060] Time period=10.mu.
[0061] Number of Cycles=1200.
[0062] A different time delay was used to avoid a situation where
both switches were ON at the same time.
[0063] The simulation parameter generates two complementary square
waves.
[0064] The simulation was performed for 25 ms as shown in the top
right of the drawing as "tran 0 25 ms 0".
[0065] Inductors L1 L2 L4 and L3 were treated as a transformer
having a perfect coupling as indicated in the top left of the
drawing "K1 L1 L2 L4 L3 1". While in the simulation, the coupling
of the transformer was modeled as "perfect", in a circuit, a
transformer would not have a "perfect" coupling.
[0066] The specific values for the resistance, capacitance and
inductance are shown in FIG. 13.
[0067] FIG. 4 shows the results of the simulation. FIG. 4 is a plot
showing the positive line (rail) voltage, negative line (rail)
voltage and logic line (rail) voltage over time. The logic line
(rail) voltage is with respect to the negative line (rail) voltage
400. Both the positive line (rail) voltage 405 and the negative
line (rail) voltage 410 are with respect to ground.
[0068] As can be seen from FIG. 4, the steady state voltage
(nominal) for the logic voltage is 5V. The steady state voltage
(nominal) for the positive voltage is 15V and the steady state
voltage (nominal) for the negative voltage is -8.7V.
[0069] Once the input voltage is turn on (V2 supplied), the logic
line (rail) voltage 400 quickly reaches its steady state voltage of
5V (around 1 ms). However, it takes around 5 ms for the positive
rail voltage to reach its steady state voltage of 15V (similar time
for the negative line voltage).
[0070] The positive and the negative line voltages decay prior to
the logic line changing voltage due to the series linear regulating
circuit 40. For example, as shown, the logic line (rail) voltage
400 remains 5V until approximately 19.5 ms. A vertical line is
shown where the logic line (rail) voltage starts to decrease. In
contrast to the logic line (rail), the positive line (rail) voltage
405 experiences as steep decay just before 18 ms and drops below 4V
when the logic line (rail) voltage 400 begins to drop. A horizontal
line intersecting the vertical line shows the positive line (rail)
voltage, when the logic line (rail) voltage starts to decrease.
[0071] Additionally, as can be seen in FIG. 4, when the logic line
(rail) voltage 400 drops below 2V, which is after approximately 25
ms, the positive line (rail) voltage 405 is about 1.3V. 2V is a
minimum guaranteed working voltage of certain circuit components of
a gate driver circuit and accompanying circuitry. Also, 1.3V is
below a gate threshold of most gated semiconductors. Thus, even in
the presence of noise, a gated semiconductor will not turn ON.
[0072] Additionally, the use of the stored energy ensures that the
gate is bias negatively as the stored gate drive energy decays.
[0073] FIG. 5 illustrates a diagram showing the output voltages of
the power supply 1 in accordance with aspects of the disclosure,
coupled to a portion of an example of a gate driver circuit. The
power supply 1 may be used with other gate driver circuits and this
disclosure is not limited to the example of a gate driver circuit,
a portion of which is depicted in FIG. 5.
[0074] As shown in FIG. 5, the example of a gate driver circuit 500
comprises a MOSFET gate driver 515 coupled to gated semiconductors,
e.g., upper and lower MOSFETs 505/510. The phrase "coupled to" used
herein refers to electrical communication and includes a direct
connection or an indirect connection through other circuit
components. In this configuration, the MOSFETs 505/510 are
configured to act as switches and are driven by the MOSFET gate
driver 515. The switching is controlled by control signal input
into a PWM pin (not shown) of the MOSFET gate driver 515. The PWM
signal may be issued from a controller via a digital isolator and
other circuit components coupled to the PWM pin.
[0075] In an aspect of the disclosure, the MOSFET gate driver 515
may be a half-bridge driver, one such driver is TPS28225 (available
from Texas Instruments, Inc.). The TPS28225 is a high-speed driver
for N-channel complimentary driven power MOSFETS.
[0076] As depicted, the drain of the upper MOSFET 505 is coupled to
a positive voltage (+v) and the source of the lower MOSFET 510 is
coupled to a negative voltage source (-v). The positive and
negative voltage is supplied by the gate driver power supply 1.
[0077] A gated semiconductor 520 is coupled between the upper
MOSFET 505 and the lower MOSFET 510.
[0078] When the upper MOSFET 505 is turned ON, the lower MOSFET 510
is turned OFF (and vice versa). In certain states, both the upper
MOSFET 505 and the lower MOSFET 510 may be OFF. The gate of the
semiconductor 520 is charged via the upper MOSFET 505 by the
positive voltage (+v) (when the upper MOSFET 505 is turned ON and
the lower MOSFET 510 is turned OFF) and discharged through the
lower MOSFET 510 to the negative voltage (-v) (when the upper
MOSFET 505 is turned OFF and the lower MOSFET 510 is turned
ON).
[0079] The gated semiconductor 520 is turned on when the
gate/emitter voltage V.sub.GE exceeds the working threshold of the
same.
[0080] The logic voltage from the gate driver power supply 1 is
supplied to the MOSFET gate driver 515 as an input voltage
V.sub.DD. There may be other circuit components between the
V.sub.DD pin of the MOSFET gate driver 515, and the input voltage
V.sub.DD (logic voltage).
[0081] The MOSFET gate driver 515 has a rated voltage range for
stable control of the gates of the upper and lower MOSFETs. The
nominal value of the logic line and thus the input voltage V.sub.DD
is greater than minimum value of the rated voltage range.
[0082] In accordance with aspects of the disclosure, since the
logic line voltage increases quickly to the steady state value,
e.g., 5V, prior to the positive line voltage (+v), the TPS 28225
(example of the driver 515) become stable to control the gated
semiconductors (MOSFETS 505/510). In other words, unintentional
turn on of MOSFET 505, which in turn would unintentionally turn on
the gated semiconductor 520 is avoided.
[0083] In an aspect of the disclosure, depending on the size of the
gated semiconductor being driven, e.g., 505/510 and 520, a boost
voltage V.sub.Boost is coupled to the floating bootstrap supply pin
of the MOSFET gate driver 515. The boost voltage V.sub.Boost helps
turn on the gated semiconductor, as needed. A capacitor (not shown)
may be added between the Boot pin and a phase pin (not shown). The
phase pin (not shown) may also be coupled to the source of the
upper MOSFET 505 and the drain of the lower MOSFET 510.
[0084] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting the
scope of the disclosure and is not intended to be exhaustive. Many
modifications and variations will be apparent to those of ordinary
skill in the art without departing from the scope and spirit of the
disclosure.
* * * * *