IGBT｜Application

IGBT IPM: Protection Functions and Operation Sequences Control Power Supply Undervoltage Lockout（UVLO) Function of IGBT IPMs

2024.04.10

Points of this article

・The control power supply undervoltage lockout (UVLO) circuit is activated if the control power supply voltage falls to a predetermined voltage or lower.

・This function is provided for both the HVIC (High Side Gate Driver) and the LVIC (Low Side Gate Driver), but an FO signal (error output) is output only when the LVIC UVLO is activated.

table of contents

This article explains the second feature, a function generally known by the acronym UVLO (for “undervoltage lockout”) that prevents malfunctions when there is a drop in the control power supply voltage.

  • Short circuit current protection（SCP）
  • Control power supply undervoltage lockout（UVLO）
  • Thermal shutdown（TSD）
  • Analog temperature output（VOT）
  • Fault output （FO）
  • Control inputs （HINU, HINV, HINW, LINU, LINV, LINW ）

Control Power Supply Undervoltage Lockout（UVLO）

When a control power supply voltage drops, the IGBT gate voltage drops as well, resulting in unwanted consequences such as a drop in IGBT performance. Hence a device must be used within the recommended power supply voltage range. If the control power supply voltage drops and falls below a predetermined voltage, the undervoltage lockout (UVLO) circuit to prevent malfunctioning upon control power supply voltage drops is activated.

A UVLO circuit is provided at both the HVIC (High Side Gate Driver) floating power supply VBS and the LVIC (Low Side Gate Driver) control power supply VCC, but an FO signal (error output) is output only when the LVIC UVLO is activated. The table below indicates the IPM operation states in the different control power supply voltage ranges.

Control power supply voltage range [V]
（VCC ,VBS ）		 Operation states
0 to 4.0 Because HVIC or LVIC is not in the normal operating voltage range, operation of the various protection functions such as UVLO and the FO signal is not guaranteed. False IGBT turn-on due to external noise or other factors is possible, and so the DC-LINK voltage must not be raised in advance of the control power supply.
4.0 to VCCUVR (VCC), VBSUVR (VBS) UVLO operates, an FO signal is output.
VCCUVR to 13.5(VCC)
VBSUVR to 13.0(VBS)		 Switching operation occurs, but because the voltage is outside the recommended operating voltage range, VCESAT and switching losses are increased, and the junction temperature may rise.
13.5 to 16.5(VCC)
13.0 to 18.5(VBS)		 The voltage is within the recommended operating voltage range, operation is normal.
16.5 to 20.0(VCC)
18.5 to 20.0(VBS)		 Switching operation occurs, but because the voltage is outside the recommended operating voltage range, noise is increased. Moreover, short circuit withstand time is insufficient, and there is a possibility of destruction.
20.0 to Destruction of HVIC or LVIC is possible. When it is possible that a rating is exceeded, placement of a Zener diode (20 to 22 V) rated at 1 W or so is recommended.

Operation Sequence for the LVCC Control Power Supply Undervoltage Lockout Function （Implemented in LVIC）

Below are shown the operation sequence and timing chart for the LVCC control power supply undervoltage lockout function installed on the LVIC side. In the explanation of operation, b1 to b8 are the operation at the points indicated in the timing chart.

  1. b1: LVCC rises, with release at VCCUVR, and the operation begins at the next LIN rising edge (each phase returns to the normal state with LIN input to the phase).
  2. b2: In normal operation, when the IGBTs are turned on an output current Ic flows.
  3. b3: LVCC drops, and upon falling below VCCUVT the protection operation begins.
  4. b4: IGBTs shut off for all lower arm phases (regardless of LIN input).
  5. b5: FO output (90 µs (Min)) when the UVLO=H interval is 90 µs or less. When the UVLO=H interval is 90 µs or longer, FO is output (FO=L) over the UVLO=H interval (until LVCC is restored).
  6. b6: When LVCC voltage rises above VCCUVR, UVLO is released.
  7. b7: Even on UVLO release at LIN=H (dashed line), IGBT is in the off state until the next LIN rising edge.
  8. b8: Normal operation. IGBTs are on, and output current Ic flows.

Operation Sequence for the VBS Control Power Supply Undervoltage Lockout Function （Implemented in HVIC）

Next, below are shown the operation sequence and timing chart for the VBS control power supply undervoltage lockout function that is installed on the HVIC side. The operation explanations c1 to c7 similarly explain operation at the points indicated in the timing chart.

  1. c1: VBS rises, with UVLO release at VBSUVR, and IGBT operation begins at the next HIN rising edge.
  2. c2: In normal operation, when the IGBTs are turned on an output current Ic flows.
  3. c3: VBS drops, and upon falling below VBSUVT the protection operation begins.
  4. c4: Only the IGBT for the corresponding phase turns off (regardless of the HIN input). FO is not output (FO remains high).
  5. c5: When LVCC voltage rises above VBSUVR, UVLO is released.
  6. c6: Even on UVLO release at HIN=H (dashed line), IGBT is in the off state until the next HIN rising edge.
  7. c7: Normal operation. IGBTs are on, and output current Ic flows.

【Download Documents】 Basics of IGBTs

IGBTs are one of the typical power devices and are used in a wide range of applications including motor drives. This handbook provides a basic understanding of IGBTs, including their application scope and application picture based on their features, their structure and principle of operation, and how they compare with and use other power devices.

Control Power Supply Undervoltage Lockout（UVLO) Function of IGBT IPMs
Download
    THIS WEBSITE USES COOKIES.
    By continuing to browse this website without changing your web-browser cookie settings, you are agreeing to our use of cookies.
    Privacy Policy
    OK